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Home , Abiquiu Formation, Aepycamelus, Albuquerque Basin, Ancha Formation, Arroyo Ojito Formation, Blancocamelus

TH FRIENDS OF THE , ROCKY MOUNTAIN-CELL, 45 FIELD CONFERENCE

PLIO-PLEISTOCENE AND GEOMORPHOLOGY OF THE CENTRAL PART OF THE

OCTOBER 12-14, 2001

SEAN D. CONNELL Bureau of Geology and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

DAVID W. LOVE New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

JOHN D. SORRELL Tribal Hydrologist, Pueblo of Isleta, P.O. Box 1270, Isleta, NM 87022

J. BRUCE J. HARRISON Dept. of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801

Open-File Report 454C and D Initial Release: October 11, 2001

New Mexico Bureau of Geology and Mineral Resources New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801 NMBGMR OFR454 C & D

INTRODUCTION

This field-guide accompanies the 45th annual Rocky Mountain Cell of the Friends of the Pleistocene (FOP), held at Isleta Lakes, New Mexico. The Friends of the Pleistocene is an informal gathering of geologists, geomorphologists, and pedologists who meet annually in the field. The field guide has been separated into two parts. Part C (open-file report 454C) contains the three-days of road logs and stop descriptions. Part D (open-file report 454D) contains a collection of mini-papers relevant to field-trip stops. This field guide is a companion to open-file report 454A and 454B, which accompanied a field trip for the annual meeting of the Rocky Mountain/South Central Section of the Geological Society of America, held in Albuquerque in late April. Errors in compiling this field-excursion are undoubtable. Please kindly inform the authors of any errors or omissions. We appologize for any unintended omissions or citations. In keeping with the informal character of Rocky Mountain Cell FOP field excursions, this guidebook contains preliminary findings of a number of concurrent projects being worked on by the trip leaders. Thus, this guidebook should be considered as a type of progress report on geologic mapping, stratigraphic work, and radioisotopic dating. The contents of the road logs and mini-papers have been placed on open file in order to make them available to the public as soon as possible. Revision of these papers is likely because of the on-going nature of work in the region. The papers have not been edited or reviewed according to New Mexico Bureau of Geology and Mineral Resources standards. The contents of this report should not be considered final and complete until published by the New Mexico Bureau of Geology and Mineral Resources. Comments on papers in this open-file report are welcome and should be made to authors. The views and preliminary conclusions contained in this report are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the State of New Mexico, Pueblo of Isleta, or the U.S. Government.

ACKNOWLEDGEMENTS

The New Mexico Bureau of Geology and Mineral Resources (P.A. Scholle, Director) supported this field trip. Much of the data presented during this field trip are from numerous open-file reports released by the New Mexico Bureau of Geology and Mineral Resources during the course of cooperative geologic mapping with the U.S. Geological Survey (New Mexico Statemap Project, P.W. Bauer, Program Manager). We are particularly grateful to the people of the Pueblo of Isleta for granting access during many of the stratigraphic and mapping studies discussed during the field trip. In particular, we thank the Honorable Alvino Lucero, Governor of Isleta, for granting access to study stratigraphically significant sites on the reservation. We are indebted to Florian Maldonado for his help and important work on the western part of the Isleta Reservation. Bill McIntosh and Nelia Dunbar provided the many important dates and tephrochronologic correlations in the Albuquerque Basin. We are grateful to John Hawley, Steven Cather, Dan Koning, and Richard Chamberlin for their assistance and advice. We thank Tien Grauch, Dirk Van Hart, and Keith Kelson for freely sharing their ideas on the geology and structure of the Isleta Reservation and Sandia National Laboratories area. In particular, the site- wide hydrologic project at Sandia National Laboratories conducted by GRAM Inc. and William Lettis and Associates (Thomas et al., 1995) was especially helpful in documenting the geology of Kirtland Air Force Base and the Sandia Labs. We also thank Jim Cole and Byron Stone for sharing some of their ideas on the late- development of the basin. David McCraw and Patricia Jackson-Paul assisted in the field and in the preparation of some of the map and poster figures. Leo Gabaldon assisted with drafting of the simplified geologic map of the Isleta Reservation. Glen Jones and Mark Mansell produced the shaded-relief images from 10-m DEM data released by the U.S. Geological Survey.

ii NMBGMR OFR454 C & D

GUIDEBOOK TABLE OF CONTENTS OPEN-FILE REPORT 454C

First Day Road Log: Geology of the Isleta Reservation S.D. Connell, D. W. Love, and J.D. Sorrell...... 1-1

Second Day Road Log: Geology of southern Albuquerque and Tijeras Arroyo S.D. Connell, D.W. Love, J.B.J. Harrison...... 2-1

Third Day Road Log: Geology of Los Lunas D.W. Love, W.C. McIntosh, N. Dunbar, and S.D. Connell ...... 3-1

MINI-PAPER TABLE OF CONTENTS OPEN-FILE REPORT 454D

Terraces of Hell Canyon and its tributaries, Memorial Draw and Ojo de la Cabra D. W. Love ...... A-1

Surface geology and liquefaction susceptibility in the inner valley of the near Albuquerque, New Mexico K.I. Kelson, C.S. Hitchcock, and C.E. Randolph ...... B-1

Stratigraphy of middle and upper Pleistocene fluvial deposits of the Rio Grande Valley (Post-Santa Fe ) and the geomorphic development of the Rio Grande Valley, northern Albuquerque Basin, central New Mexico S.D. Connell and D. W. Love ...... C-1

Summary of and Irvingtonian ( and ) mammalian biochronology of New Mexico (reprinted from NMBMMR Open-file report 454B) G.S. Morgan, and S.G. Lucas ...... D-1

Plio-Pleistocene mammalian biostratigraphy and biochronology at Tijeras Arroyo, Bernalillo County, New Mexico (reprinted from NMBMMR Open-file report 454B) G.S. Morgan and S.G. Lucas ...... E-1

Cuspate-lobate folds along a sedimentary contact, Los Lunas volcano, New Mexico (reprinted from NMBMMR Bulletin 137) W.C. Haneberg...... F-1

iii NMBGMR OFR454 C & D

Plate I. Shaded-relief map of the Isleta Reservation and southern Albuquerque field-trip area illustrating the locations of day 1 (black square), day 2 (black diamond), and day 3 (white diamond) stops. All trips start from the Isleta Lakes Campground (black circle) in the inner valley of the Rio Grande. The Llano de Albuquerque is a broad, south-sloping interfluve between the Rio Puerco and Rio Grande Valleys, which was formed during late Pliocene time. The hachured lines indicate the approximate boundary of inset fluvial terrace deposits of the Rio Grande Valley. The broad low-relief surfaces east of the Rio Grande Valley contain the Pleistocene Sunport (SP) and Llano de Manzano surfaces, and the Pliocene Cañada Colorada surface (CC). The approximate eastern and western limits of the axial-fluvial Rio Grande (a) is denoted depicted by white dotted lines. TC and HC indicate the mouths of Tijeras, and Hell Canyons, respectively. Nearly all of the north- and northwest-trending scarps are faults that cut these geomorphic surfaces. Base from shaded-relief image in Maldonado et al. (1999) and was prepared from 10-m DEM data from the National Elevation Database of the U.S. Geological Survey.

iv NMBGMR OFR454 C & D

Plate II. Simplified geologic map of the Albuquerque Basin (Connell, in preparation).

v NMBGMR OFR454 C & D

Plate III. Stratigraphic correlation diagrams of deposits in the central Albuquerque Basin and southern . Black triangles and circles denote radioisotopically dated primary, and fluvially recycled volcanic products, respectively. Bones denote biostratigraphically significant sites. Volcanic units are shaded. Dates are from various sources and noted in Ma. Deposits of Zia Fm include the Chamisa Mesa (C. Mesa) and Cañada Pilares (CPM) mbrs. (RLB) and Irvingtonian (Irv) are Pleistocene divisions of the North American Land Mammal “ages.”

vi STRATIGRAPHY AND TECTONIC DEVELOPMENT OF THE ALBUQUERQUE BASIN, CENTRAL RIO GRANDE

FIELD-TRIP GUIDEBOOK FOR THE GEOLOGICAL SOCIETY OF AMERICA ROCKY MOUNTAIN-SOUTH CENTRAL SECTION MEETING, ALBUQUERQUE, NM PRE-MEETINNG FIELD TRIP

GUIDEBOOK

FIRST DAY, SANTO DOMINGO SUB-BASIN: HAGAN EMBAYMENT AND NORTHERN FLANK OF THE

SECOND DAY, CALABACILLAS SUB-BASIN: ZIA PUEBLO, RIO RANCHO, AND TIJERAS ARROYO

THIRD DAY, BELEN SUB-BASIN: BELEN, SEVILLETA NATIONAL WILDLIFE REFUGE, AND NORTHERN SOCORRO BASIN

Trip Leaders

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office 2808 Central Ave. SE, Albuquerque, NM 87106

DAVID W. LOVE New Mexico Bureau of Mines and Mineral Resources 801 Leroy Place, Socorro, NM 8701

SPENCER G. LUCAS New Mexico Museum of Natural History and Science 1801 Mountain Rd. NW, Albuquerque, NM 87104

DANIEL J. KONING Consulting Geologist, 14193 Henderson Dr., Rancho Cucamonga, CA 91739

NATHALIE N. DERRICK Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801

STEPHEN R. MAYNARD Consulting Geologist, 4015 Carlisle, NE, Suite E, Albuquerque, NM 87107

GARY S. MORGAN New Mexico Museum of Natural History and Science, 1801 Mountain Road N.W., Albuquerque, NM 87104

PATRICIA B. JACKSON-PAUL New Mexico Bureau of Mines and Mineral Resources- Albuquerque Office, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

RICHARD CHAMBERLIN New Mexico Bureau of Mines and Mineral Resources, 801 Leroy Place, Socorro, NM 87801

Open-File Report 454A Initial Release: April 27, 2001 Revised June 11, 2001

New Mexico Bureau of Mines and Mineral Resources New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801 NMBMMR 454A REVISIONS TO GUIDEBOOK AND MINI-PAPERS

This field-guide accompanied a pre-meeting field trip of the Geological Society of America Rocky Mountain and South-Central Section conference in Albuquerque, New Mexico. A limited quantity of guidebooks and mini- paper compilations were produced for participants of this field trip. A number of typographical, grammatical, and editorial errors were found in this first version of the guidebook, mainly because of logistical constraints during preparation for the field trip. In the revised version, released on June 11, 2001, many errors have been corrected. Many photographs, figures, and maps, shown during the field trip but not included in the first version, are included in this revision. Numerous minor editorial changes and corrections have also been made to the guidebook mini- papers. The field-guide has been separated into two parts. Part A (open-file report 454A) contains the three-days of road logs and stop descriptions. Part B (open-file report 454B) contains a collection of mini-papers relevant to field-trip stops. The contents of the road logs and mini-papers have been placed on open file in order to make them available to the public as soon as possible. Revision of these papers is likely because of the on-going nature of work in the region. The papers have not been edited or reviewed according to New Mexico Bureau of Mines and Mineral Resources standards. The contents of this report should not be considered final and complete until published by the New Mexico Bureau of Mines and Mineral Resources. Comments on papers in this open-file report are welcome and should be made to authors. The views and preliminary conclusions contained in this report are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the State of New Mexico or the U.S. Government.

ACKNOWLEDGEMENTS

This field trip was supported by the New Mexico Bureau of Mines and Mineral Resources (P.A. Scholle, Director) and the New Mexico Museum of Natural History and Science. Much of the data presented during this field trip are from numerous open-file reports released by the New Mexico Bureau of Mines and Mineral Resources during the course of cooperative geologic mapping with the U.S. Geological Survey (New Mexico Statemap Project, P.W. Bauer, Program Manager). We are particularly grateful to the Pueblos of Zia, Isleta, Sandia, San Felipe, Santo Domingo, Jemez, and Santa Ana for granting access during many of the stratigraphic and mapping studies discussed during the field trip. In particular, we thank Mr. Peter Pino for enabling access to study the stratigraphically significant localities along the Rincones de Zia. We also thank Mr. Gary Nolan, Mr. Jerry Burke, and Mr. Mackie McClure for allowing access to the LaFarge and SunCountry Redimix gravel quarries near Bernalillo, New Mexico. We also thank Ms. Leanne Duree of the Ball Ranch for allowing access through their lands on Tanos Arroyo. We thank the New Mexico Geological Society for granting permission to reprint three papers from their 1999 Guidebook 50 entitled Albuquerque Geology (F.J. Pazzaglia and S.G. Lucas, eds). We especially thank V.J.S. Grauch for agreeing to present summaries of recent regional geophysical surveys of the Albuquerque Basin.

ii NMBMMR 454A

GUIDEBOOK TABLE OF CONTENTS

First Day, Santo Domingo Sub-Basin: Hagan Embayment and Northern Flank of the Sandia Mountains S.D. Connell, S.G. Lucas, D.J. Koning, S.R. Maynard, N.N. Derrick...... 1

Second Day, Calabacillas Sub-Basin: Zia Pueblo, Rio Rancho, and Tijeras Arroyo S.D. Connell, D.J. Koning, N.N. Derrick, D.W. Love, S.G. Lucas, S.G. Lucas, G.S. Morgan, and P.B. Jackson-Paul...... 17

Third Day, Belen Sub-Basin: Belen, Sevilleta National Wildlife Refuge, and Northern Socorro Basin D.W. Love, S.D. Connell, S.G. Lucas, G.S. Morgan, N.N. Derrick, P.B. Jackson-Paul, and R.M. Chamberlin .....27

iii NMBMMR 454A GEOLOGICAL SOCIETY OF AMERICA ROCKY MOUNTAIN-SOUTH CENTRAL SECTION MEETING, ALBUQUERQUE, NM PRE-MEETINNG FIELD TRIP: STRATIGRAPHY AND TECTONIC DEVELOPMENT OF THE ALBUQUERQUE BASIN, CENTRAL

FIRST DAY ROAD LOG, APRIL 27, 2001 SANTO DOMINGO SUB-BASIN: HAGAN EMBAYMENT AND NORTHERN FLANK OF THE SANDIA MOUNTAINS

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office 2808 Central Ave. SE, Albuquerque, NM 87106

SPENCER G. LUCAS New Mexico Museum of Natural History and Science 1801 Mountain Rd. NW, Albuquerque, NM 87104

DANIEL J. KONING Consulting Geologist, 14193 Henderson Dr., Rancho Cucamonga, CA 91739

STEPHEN R. MAYNARD Consulting Geologist, 4015 Carlisle, NE, Suite E, Albuquerque, NM 87107

NATHALIE N. DERRICK Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801

The following road log through the Santo Domingo sub-basin has been summarized and modified from New Mexico Geological Society Guidebook 50 by Pazzaglia et al. (1999a) and Hawley and Galusha (1978). Road-log mileage not checked for accuracy.

Mileage Description 6.8 Gravel quarries on your left are excavating 0.0 Load vehicles at Sheraton Old Town hotel. aggregate from the Edith Fm, an extensive Turn right (North) on Rio Grande Blvd. 0.3 and important marker unit originally defined 0.3 Cross under 1-40 overpass. 1.4 by Lambert (1968) for exposures along 1.7 Turn right (east) onto Candelaria Blvd. 1.8 Edith Blvd. Many of the original exposures 3.5 Cross drain at corner of 2nd Street and along Edith Blvd. are being covered or Candelaria. 0.2 obscured by urban development. The Edith 3.7 Cross Railroad tracks. 0.2 Fm locally yields fossil of 3.9 Cross Edith Blvd. and begin ascending Rancholabrean age (~400-10 ka), including -latest Pleistocene valley border , , horse, and ground sloth fans derived from the Sandia Mts. These (Lucas et al., 1988). On your left, north to alluvial deposits grade over, and interfinger exit 230 are a number of with, floodplain and old channel deposits of industrial/commercial tracts constructed on the Rio Grande. 0.7 reclaimed aggregate quarries in the Edith 4.6 Turn left onto North Frontage Rd. (Pan Fm. On your right is the rugged western American Highway). Keep to your left and escarpment of the Sandia Mts. Rincon Ridge merge onto I-25 northbound to Santa Fe. is between 1:00-2:00. Well-sorted axial- The flows and splatter cones to your fluvial sand and gravel of the ancestral Rio left across the Rio Grande Valley are the Grande underlie locally derived piedmont Albuquerque volcanoes, which have been deposits of the rift-bounding Sandia Mts. to dated (238U/230Th method) at 156±29 ka the east. These fluvial deposits constitute the (Peate et al., 1996). These basalt flows narrow axial-fluvial lithofacies of the interfinger with the upper part of am ancestral Rio Grande, which represent some ancestral Rio Grande fluvial deposit of the of the best aquifer units of the Santa Fe Los Duranes Fm, which was originally Group. Deposits of the ancestral Rio Grande defined by Lambert (1968). 1.6 basin fill are mostly between Eubank and 6.2 Pass under Montaño Blvd. (exit 228). 0.6 Edith Blvds. 1.8

1 NMBMMR 454A

Figure 1-1. Shaded-relief map of the Albuquerque area, illustrating the locations of stops for day 1 (black circles), and day 2 (white squares). Base prepared by S.D. Connell for Pazzaglia et al. (1999b).

2 NMBMMR 454A

3 NMBMMR 454A

typically associated with landscaping irrigation or leaking water or sewer pipes. 1.0 9.6 Paseo del Norte Blvd. overpass (exit 232). 1.1 10.7 To the left are computer chip production facilities run by Phillips and Sumitomo Sitix, which have cooperated with the City of Albuquerque on a joint water reclamation project to recycle water for use on the grounds of Balloon Fiesta Park. 0.8 11.5 Southern boundary of Sandia Pueblo. 0.1 11.6 Milepost 234. Tramway Blvd./Roy Avenue underpass. at 10:00, Jemez Mts. and at Santa Ana Mesa (a.k.a. San Felipe Mesa) at 11:00, Sandia Mts. at 3:00. The cliffs consists of the 1.44 Ga Sandia granite, which intruded into the 1.7 Ga Rincon Ridge metamorphic complex. These crystalline rocks are nonconformably overlain by the Pennsylvanian Sandia and Madera fms. to Holocene valley border deposits are inset against the Edith Fm to the north, but overlie the Edith Fm to the south. The entrenchment of younger alluvium into the Edith Fm is attributed to broad deformation across the northwest-trending Alameda structural zone (Pazzaglia et al., 1999a). Quaternary deformation is interpreted here, primarily because the basal contact (strath) of the Edith Fm decreases in elevation by about 15 m across this inferred structural zone (Connell, 1998) and younger piedmont Figure 1-2. Explanation and simplified geologic map alluvium is inset against the Edith Fm to the of the southeastern Santo Domingo sub-basin north. To the west are abandoned and (previous page), illustrating locations of Day 1 stop reclaimed quarries in the Edith Fm. Current localities (compiled from Cather and Connell, 1998; quarry operations are to the north. 2.9 Cather et al., 2000; Connell, 1998, Connell et al., 14.5 Milepost 237. At about 9:00, west of the 1995; unpublished mapping). Bandelier and Rio Grande Valley is Loma Colorada del Cerro Toledo are found as fallout ash and Abajo, a low hill underlain by Pliocene-aged lapilli and, more commonly, as fluvially recycled light gray sandy gravel of the Ceja Mbr, pebbles and cobbles. which overlies reddish-brown sediments of the Loma Barbon Mbr (same formation, 8.6 San Antonio Drive overpass (exit 231). Pliocene). To your left is an unconformable Latest Pleistocene and Holocene piedmont contact between the Edith Fm and slightly deposits derived from Sandia Mts. form east-tilted reddish-brown strata assigned to valley border fans that overlie the Edith Fm. the Loma Barbon Mbr. 2.0 Many of the larger buildings immediately 16.5 Milepost 239. Edith Fm overlies east-tilted east and west of I-25 in this area have been red of the Loma Barbon Mbr. 2.7 affected by structural damage attributed to 19.2 On your right, reddish-brown Loma Barbon hydrocollapsing soils associated with these Mbr unconformably overlain by rounded young silty sands, which are typically less quartzite-bearing gravel of the Edith Fm. dense than the older piedmont deposits, have 0.3 higher blow counts during percussion 19.5 Exit 242 to Rio Rancho and Placitas, drilling, and consolidate when wetted. These highways NM-165 and US-550. 0.2 soils are susceptible to compaction when 19.7 Overpass of US-550 and NM-165. 0.8 they receive large amounts of moisture,

4 NMBMMR OFR 454A 20.5 Milepost 243. Centex Gypsum wallboard 29.8 Exit 252. Overpass to San Felipe Pueblo. production plant on the left at 9:00. This Crossing over Tonque Arroyo. 0.7 plant processes gypsum from local quarries developed in the Todilto Fm, some of which is locally mined from exposures along the basin margin. 1.0 21.5 Milepost 244. Maar of Canjilon (octopus) Hill at 9:00. This volcanic edifice was K/Ar dated at 2.6±0.1 Ma (Kelley and Kudo, 1977). Between 10:00 and 11:00, are the east-tilted and faulted basalts at Santa Ana Mesa. Recent 40Ar/39Ar dates along the southeastern margin indicate these flows were emplaced between 2.24-1.77 Ma (W.C. Figure 1-3. Photo looking to the north near Milepost McIntosh, 1997, written commun.; Cather 249. Plio-Pleistocene ancestral Rio Grande deposits and Connell, 1998). 1.0 of the Sierra Ladrones Fm (ARG) interfinger with 22.5 Milepost 245. Ascending hill underlain by this Pliocene basalt. middle to late Pleistocene (post-) piedmont deposits overlying Edith 30.5 On your left is a northeast-tilted, white ash Fm. 1.5 bed. Along the south side of Tonque Arroyo, 24.0 Las Huertas Creek. 0.3 just east of the San Felipe Casino, this ash 24.3 Middle to late Pleistocene piedmont deposits bed is at the contact between fluvial deposits overlying the Edith Fm. 0.4 of the ancestral Rio Grande and overlying 24.7 Between 9:00 and 10:00 are interbedded piedmont deposits. This ash bed was dated reddish brown sand of the Arroyo Ojito Fm using the 40Ar/39Ar method at 1.57±0.06 Ma and light-gray sand of the ancestral Rio (W.C. McIntosh, 1998, written commun.) Grande facies (Sierra Ladrones Fm) beneath and is chemically similar to the Cerro the basalt flows at Santa Ana Mesa. 0.7 Toledo Rhyolite (N. Dunbar, 2000, written 25.4 Exit 248. Algodones overpass. 0.4 commun), a series of eruptions between the 25.8 On your left is the Plains Electric generation collapse events of the lower and plant. The hummocky topography flanking upper in the Jemez Mts. 0.4 the basalt flows at Santa Ana Mesa is 30.9 To the north between 11:00 and 12:00 is the formed by Pleistocene landslides that locally Cerros del Rio , which is on cover inset fluvial (fill-terrace) deposits of the footwall of the La Bajada fault. Tetilla the ancestral Rio Grande (Cather and Peak is at 11:00. 0.8 Connell, 1998). 0.6 31.7 Crossing Arroyo de la Vega de los Tanos 26.4 Milepost 249. To your left are moderately (Tanos Arroyo). On your right, Espinaso dipping cliffs of older piedmont deposits of ridge is held up by upper and the Santa Fe Group, exposed in Arroyo volcaniclastic deposits of the Maria Chavez. 0.6 Espinaso Fm, which conformably overlies 27.0 At 10:00, a basalt flow of the Santa Ana the Eocene Galisteo Fm. The Ortiz Mts., at Mesa basalts is cut by the Escala fault, 3:00, are the source of detritus for the which is a prominent down-to-west fault that Espinaso Fm at Espinaso Ridge. The begins south at the northern flank of the northern tip of Espinaso Ridge is cut by the Sandia Mts., near Placitas. The eastern San Francisco fault. This fault is another margin of these basalt flows and vents are major down-to-west normal fault that begins exposed on Santa Ana Mesa but descend at the northern flank of the Sandia Mts., near eastward where they are interbedded with Placitas. 1.7 ancestral Rio Grande (fluvial) deposits of 33.4 On your left are the Jemez Mts. Between the Sierra Ladrones Fm (Fig. 1-3). 1.2 9:00 and 10:00, Tent Rocks underlain by 28.2 On the right is a gravel quarry in the late Peralta Tuff Mbr of the ancestral Rio Grande deposits of the Sierra Bearhead Rhyolite. Some of the oldest Ladrones Fm (upper Santa Fe Group). 1.0 deposits of the ancestral Rio Grande are 29.2 On the left is a succession of sandy recognized in ~6.9 Ma beds of the Peralta piedmont deposits of the Sierra Ladrones Tuff at Tent Rocks (Smith and Kuhle, Fm that overlie ancestral Rio Grande 1998). The Cerrillos Hills, another deposits (ARG) of the same formation. Oligocene-age intrusive and volcanic center, These piedmont deposits interfinger with related to the Ortiz Mts., is between 10:00 fluvial facies to the east. 0.6 and 1:00. 1.2 5 NMBMMR OFR 454A 34.6 Leave I-25 at Budaghers exit (exit 257). 0.3 The Oligocene Espinaso Fm conformably 34.9 Turn right onto Budaghers Blvd. at stop sign overlies the Galisteo Fm, but marks a distinct change at top of offramp. 0.1 in deposition. The Espinaso Fm was defined by 35.0 Make a sharp right onto east frontage road. Stearns (1953a) for volcaniclastic detritus shed off of The cliffs in the quarry to your left contain the Ortiz Mts., a lacolithic and volcanic complex, well cemented sandstone and travertine of ~12-15 km east of this stop, emplaced between 27-36 the upper Santa Fe Group, on the footwall of Ma. The Espinaso Fm was deposited as volcanic and the San Francisco fault. 0.4 hypabyssal intrusive rocks were eroded off the Ortiz 35.4 Cross cattleguard, pavement ends at Arroyo Mts. The Espinaso Fm is about 430 m here and Vega Tanos Rd. Proceed on dirt road to the contains a lower member composed of calc-alkaline left. 0.4 rocks (hornblende+pyroxene) that are overlain by an 35.8 Low hills to the left are topographic scarps upper alkaline (biotite+clinopyroxene) member of the Budaghers fault. 0.4 (Erskine and Smith, 1993). 36.2 To your left, note well cemented piedmont Deposits of the Santa Fe Group (Spiegel and pebbly sandstone of the Blackshare Fm. 0.1 Baldwin, 1963) are generally differentiated into two, 36.3 Cross through cattle gate and make a sharp and in some places three, informal sub-groups (Bryan left. You must obtain permission from the and McCann, 1937, 1938; Lambert, 1968; Kelley, Ball Ranch prior to passing this gate, 1977; Hawley, 1978, 1996; Hawley et al., 1995). which is normally locked. 0.2 These sub-groups are divided into a number of 36.5 Crossing Tanos Arroyo. 1.2 formation- and member-rank units throughout much 37.7 Pass through cattle gate. 0.1 of the Española, Albuquerque, Socorro, and Palomas 37.8 Around you is mudstone and sandstone of basins. The lower sub-group records deposition in the Tanos Fm, which is commonly overlain internally drained basins (bolsons) where streams by gravelly Quaternary alluvium. 0.9 terminated at broad alluvial plains or ephemeral or 38.7 STOP 1: Oligocene through middle intermittent playa lakes bounded by basin-margin Miocene deposits of the Lower Santa Fe piedmont deposits derived from emerging rift- Group at Arroyo de la Vega de los Tanos flanking uplifts. The upper sub-group records (Tanos Arroyo). San Felipe Pueblo NE 7.5’ deposition in externally drained basins where quadrangle, GPS: NAD 83, UTM Zone 013 perennial streams and rivers associated with the S, N: 3,920,012 m; E: 380,479 m. ancestral Rio Grande fluvial system flowed toward The purposes of this stop are to: 1) summarize southern New Mexico. Deposition ceased during the geology of Paleogene pre-rift rocks of the Pleistocene time, when the Rio Grande began to Espinaso, Galisteo, and Diamond Tail fms; 2) discuss incise into the earlier aggradational phase of the the Oligocene hypabyssal intrusive and volcanic Santa Fe Group basin fill (Spiegel and Baldwin, rocks of the Ortiz porphyry belt; 3) examine the 1963; Hawley, 1996; Hawley et al., 1969). oldest, dated, exposed section of lower Santa Fe The northeastern flank of Espinaso Ridge Group in the Hagan embayment. exposes some of the oldest deposits of the Santa Fe The Hagan embayment is a structural re-entrant Group in the Albuquerque Basin (see mini-paper by formed between the San Francisco and La Bajada Connell and Cather, this volume). The Tanos Fm is faults. The embayment marks the eastern boundary of the stratigraphically lowest preserved deposits of the the rift and contains a well exposed succession Santa Fe Group exposed in the northern Albuquerque sedimentary rocks, encompassing much of the basin. The Tanos Fm rests disconformably upon Pennsylvanian-Pleistocene geologic record. The Oligocene volcaniclastic conglomerate and sandstone discussion of pre-Espinaso Fm rocks is summarized of the Espinaso Fm (Fig. 1-4). The contact is sharp from Pazzaglia et al. (1999a, b). and stratal tilts do not change noticeably across this The Diamond Tail and Galisteo fms comprise boundary; however, a continuous dip-meter log from upper Paleocene and Eocene sedimentary rocks that a nearby oil test well indicates an angular relationship were deposited in the , a Laramide at this contact. The Tanos Fm is subdivided into three basin developed in response to -cored unmapped members: basal conglomeratic piedmont, uplifts in the current location of the Sangre de Cristo middle mudstone and sandstone, and upper tabular and Nacimiento Mts. Paleocurrent data indicate sandstone. The basal member contains 25.41 Ma deposition in the Galisteo basin was by extensive olivine basalt about 9 m above the base. The middle river systems flowing to the south (Gorham and mudstone member represents a basin-floor playa-lake Ingersoll, 1979; Kautz, 1981; Smith, 1992). The facies of the Tanos Fm (Fig. 1-5). thickness of the Diamond Tail and Galisteo fms is as The Tanos Fm is conformably overlain by the much as 1300 m. Fossil mammals indicate deposition Blackshare Fm, which contains conglomeratic began in the early Eocene (~54 Ma) and continued sandstone, sandstone, and mudstone, commonly through the latest Eocene (~37 Ma) (Lucas et al., arranged in upward fining sequences bounded by 1997). weakly developed soils (Fig. 1-6). The basal contact

6 NMBMMR OFR 454A of the Blackshare Fm interfingers with the Tanos Fm in abundance within the overlying Blackshare Fm. and is mostly covered by Quaternary alluvium in These hornfels are exposed near the flanks of the Tanos Arroyo. An 11.65 Ma ash is about 670-710 m Ortiz Mts. and were metamorphosed during (based on measured sections and estimated from emplacement of the Ortiz porphyry at about 27-36 geologic map of Cather et al., 2000) above the base. Ma (Maynard, 1995). of the Espinaso Fm are quartz-poor lithic arkoses, whereas those of the overlying deposits of the Santa Fe Group are lithic arkose and feldspathic litharenite containing more quartz than in the underlying Espinaso Fm.

Figure 1-4. Contact between white conglomeratic sandstone of the Espinaso Fm (left) and overlying conglomerate of the Tanos Fm (right).

Figure 1-6. Blackshare Fm. Conglomerate facies (top), and upward-fining sequences of conglomeratic sandstone, sandstone, and mudstone (bottom). Figure 1-5. Moderately northeast-dipping (to the right) basin-floor facies of the middle mudstone End of Stop 1. Proceed south-southeast member of the Tanos Fm. along dirt road. 0.4 39.1 Cross Tanos Arroyo. 0.3 Composition, gravel size, and paleocurrent data 39.4 Cross under power lines. 0.1 indicate derivation from the Ortiz Mts. (Large and 39.5 Blackshare Ranch is straight ahead. Pass Ingersoll, 1997; Cather et al., 2000). The Espinaso, through the cattle gate and take a sharp and Tanos, and Blackshare fms contain abundant immediate right. 0.5 porphyritic hypabyssal intrusive and volcanic rocks 40.0 To your left is a north-trending normal fault derived from the neighboring Ortiz Mts., which are with down-to-the-west movement. Pink beds exposed on the footwall of the La Bajada fault. The in stream cut near arroyo terminate at the upper Espinaso Fm contains alkalic rocks, as fault. Within about 100 m west of this fault described by Erskine and Smith (1993). Overlying is a topographic scarp of the major fault deposits of the Tanos Fm contain a more diverse from which this fault is a splay. 0.2 assemblage of hypabyssal intrusive and volcanic 40.2 Cross tributary of Tanos Arroyo. 0.1 gravels. Thermally metamorphosed shales 40.3 Pass through cattle gate and cross small and sandstones (hornfels) and fine rounded quartzite arroyo. 0.9 pebbles are very rare near the base, but they increase

7 NMBMMR OFR 454A 41.2 Ruin to your right. Keep straight and cross suggests that this unit is probably too old to be over earthen dam. 0.4 correlative to the Ancha Fm. Much of this section is 41.6 Make a hard right at the intersection of two lithologically similar to the Pojoaque Mbr of the dirt roads. 0.3 Tesuque Fm. Therefore, we consider most of the type 41.9 Bear left. Ascend hill to broad alluvial Ancha section to be correlative to the underlying surface of the Tuerto Fm. 1.0 Tesuque Fm. The Ancha Fm was mapped as a 42.9 Cross arroyo. 0.8 granite-bearing gravel and sand derived from the 43.7 Windmill on your right. 0.1 southwestern front of the Sangre de Cristo Mts. in the 43.8 Turn right onto weakly developed two-track Santa Fe embayment, near Santa Fe, New Mexico. road. 0.1 Exposures extend from just north of the Santa Fe 43.9 STOP 2: Plio-Pleistocene basin-margin River, to Galisteo Creek. Although the type section gravels of the Tuerto Fm. San Felipe Pueblo of this unit was mis-correlated by Spiegel and NE 7.5’ quadrangle, GPS: NAD 83, UTM Baldwin (1963), it has been mapped in a consistent Zone 013 S, N: 3,915,540 m; E: 380,210 m. manner throughout the Santa Fe embayment and, The purposes of this stop are to: 1) summarize thus is a stratigraphically useful term. Therefore, we the geology of Plio-Pleistocene basin-margin deposits propose replacing the Cañada Ancha section with a of the Tuerto and Ancha fms; 2) discuss the new type section near Lamy, New Mexico. development of the La Bajada fault zone. Deposits of the Tuerto Fm (upper Santa Fe Group) overlying moderately tilted beds of the Tanos and Espinaso fms, just south of the Arroyo del Tuerto (Arroyo Pinovetito of Stearns, 1953a) section along Tanos Arroyo (Fig. 1-7). The purposes of this stop are to: 1) examine the Tuerto Fm and compare it to the Ancha Fm of the Santa Fe embayment; and 2) discuss the influence of basin-bordering faults, such as the La Bajada fault. The top and base of this unit have been considered part of the Ortiz surface (Stearns, 1979). We assign the upper constructional surface to the Ortiz, also recognizing the stratigraphic Figure 1-7. View to south of angular and structural importance of the underlying between northeast-tilted beds of the Espinaso Fm unconformity. (white) and overlying sub-horizontally bedded Tuerto Stearns (1953a) informally named the Tuerto Fm Fm. Sandia Mts. in background. for a broad alluvial gravel associated with streams draining the Ortiz Mts. and Cerrillos Hills. The The Ancha Fm contains abundant granite with Tuerto Fm generally ranges from about 10 to 21 m in less amounts of gneiss and schist. The Ancha Fm is thickness and is readily distinguished by its angular compositionally distinct from the Tuerto Fm, which basal contact with tilted beds of the Espinaso, Tanos, contains porphyrytic and monzanite and and Blackshare fms, and by a marked increase in hornfels derived from the Ortiz Mts. The Tuerto Fm maximum gravel size (cobbles and boulders are locally overlies the Ancha Fm along the southern locally common) and increase in the proportion of margin of Galisteo Creek, indicating that these two hornfels gravel. The Tuerto Fm forms an areally formations are coeval in part. The Tuerto and Ancha extensive alluvial apron. It unconformably overlies fms are locally overlain by Pliocene basalt flows of the Espinaso, Tanos, and Blackshare fms. The the Cerros del Rio field, which were mostly emplaced Espinaso Fm and cemented conglomerates of the between 2.3 and 2.8 Ma (cf. Woldegabriel et al., Blackshare Fm typically form low hills inset by the 1996). The age of the Ancha Fm is constrained by the Tuerto Fm. presence of tephra Ar/Ar dated at 1.48 Ma, which is A thin, unnamed -bearing deposit is temporally correlative to the Cerro Toledo Rhyolite, recognized south of the main belt of Tuerto Fm from the Jemez Mts. This ash, and another dated at outcrops, just south of San Pedro Creek. These 1.61 Ma, lie near the top of the Ancha Fm (Read et limestone-bearing deposits constitute a lithologically al., 2000). In Bonanza Wash, just east of the Cerro differentiable unit that is coeval with the Tuerto Fm Bonanza in the Cerrillos Hills, an ash containing 1.26 that has not yet been differentiated. Ma tephra is recognized in deposits associated with Spiegel and Baldwin (1963) defined the Ancha Bonanza Creek (Koning et al., this volume). This ash- Fm as the uppermost part of the Santa Fe Group. bearing deposit is interpreted to be inset against the They defined this deposit for exposures along Canada Ancha Fm. Thus, the entrenchment of the Ancha Fm, Ancha, where an interbedded ash was recently dated near Bonanza Creek, began between 1.5 and 1.2 Ma. at 8.48±0.14 Ma using the 40Ar/39Ar method (see This entrenchment of the Ancha constructional mini-paper by Koning et al., this volume), which surface, called the Plains surface by Spiegel and

8 NMBMMR OFR 454A Baldwin (1963), was probably not synchronous. The 48.6 Bear right. 0.1 Ancha Fm is thin and contains fallout tephra of the 48.7 Merge right. 0.6 lower Bandelier Tuff (Read et al., 2000) near the 49.3 Pass through cattle gate. Turn left onto dirt mouth of Arroyo Hondo, suggesting that the Ancha road (NM-22). To your right is the La Fm was deposits during early Pleistocene time along Bajada fault capped by Pliocene basalts of that segment of the mountain front. Along the the Cerros del Rio volcanic field. To the southern flank of the Sangre de Cristo Mts., granitic north are the Cerrillos Hills. 2.0 deposits containing preserved constructional deposit 51.3 Descend northeast-trending scarp of tops have only weakly developed soils, commonly Budagher fault, which has down-to-the- exhibiting Stage I to II carbonate morphology. These northwest normal movement. The Budagher deposits are nearly indistinguishable from the fault is mapped between the San Francisco underlying Ancha Fm and are not differentiated on and La Bajada faults and probably maps. This weak soil development suggests that represents a hard-linked relay fault between deposition of the Ancha Fm deposition continued into these rift-border structures. 1.6 the middle Pleistocene along parts of the front of the 52.9 Left onto I-25 southbound onramp. 1.6 southern Sangre de Cristo Mts., especially near Seton 54.5 East tilted mudstone and sandstone of Sierra Village, New Mexico. Similar soil-geomorphic Ladrones Fm piedmont deposits on your relationships are recognized in the Tuerto Fm along left. 0.5 the flanks of the Ortiz Mts. 55.0 Driving over approximate location of trace These three units are relatively thin, of the San Francisco fault, which is buried unconformably overlie older rocks with distinct here by Quaternary sediments. 2.6 angularity, and are recognized along the rift margin 57.6 Gray sands at the bottom of arroyo face where they are associated with mountainous contain Bandelier Tuff. White beds along I- drainages. These deposits locally contain an 25 are correlated to a 1.57 Ma ash of one of unmapped, well cemented lower member that is the Cerro Toledo events (see notes for overlain by poorly exposed, weakly cemented upper mileage 30.5). 0.9 members that contain remnants of soils exhibiting 58.5 Cuestas at 9:00 are Dakota Sandstone. Stage II to III+ carbonate morphology. The well Underlying white deposits are Todilto Fm cemented units contain abundance fine- to medium- gypsum beds exposed at a quarry. 0.5 grained sparry calcite, suggesting prolonged 59.0 White ash of 1.57 Ma Cerro Toledo Rhyolite saturation of these deposits by groundwater. Younger at 10:00 (see notes for mileage 30.5). 0.5 inset alluvial and fluvial deposits typically do not 59.5 Tonque Arroyo overpass. To the right, the contain such well cemented intervals, presumably eastern edge of the upper Pliocene basalts at because they were deposited during long-term Santa Ana Mesa are interbedded with dissection of tributary drainages. These deposits ancestral Rio Grande deposits of the Sierra would constitute members of a formation, however, Ladrones Fm. 1.2 they all contain locally differentiable sub-units, thus 60.7 To your left are brownish-yellow stained rendering a member rank for these units problematic. fluvial Sierra Ladrones deposits. This zone These units comprise a group of relatively thin strata of staining is along a north-trending zone associated with faulted basin-margin flanks that that is the northern extension of a north- record a slightly different geologic history compared trending fault mapped to the south. 1.5 to nearly continuous deposition within sub-basin 62.2 This stretch of the highway contains a depocenters. number of irregular dips associated with North of NM-22, the Tuerto Fm is cut by the La hydrocollapsible soils of latest Pleistocene- Bajada fault, however, displacements significantly Holocene valley border fan deposits derived decrease to the south and probably bury the southern from sandy deposits of the upper Santa Fe tip of the La Bajada fault.. Group to the east. 5.8 End of Stop 2. Turn vehicles around and 68.0 Water tanks to the left sit on a middle retrace steps to dirt road. 2.0 Pleistocene piedmont gravel that 45.9 Bear right. 0.4 unconformably overlies reddish-brown 46.3 At intersection, go straight. 0.4 sandstone of the Loma Barbon Mbr of the 46.7 Take a sharp left. 0.5 Arroyo Ojito Fm. Assignment of these 47.2 Gravel on top of ridge may be remnants of reddish-brown sediments to the Arroyo Tuerto Fm. 0.6 Ojito Fm is ambiguous, primarily because of 47.8 Pass through cattle gate. Keep right. Metal the paucity of gravel. This assignment is pole near road to your left is the Marion Oil made primarily based on comparisons to Co. Blackshare No. 2 oil test well, which similar strata exposed west of the Rio ended in the Morrison Fm at 2079 m (6820 Grande valley. 1.5 ft) below land surface. 0.8

9 NMBMMR OFR 454A 69.5 Bear right and leave I-25 at Placitas and these deposits are conformable further into Bernalillo offramp (exit 242). 0.2 the basin. This relationship suggests that the 69.7 Turn left at the stop sign at the top of the La Huertas geomorphic surface marks a offramp. 0.7 local top of the upper Santa Fe Group on the 70.4 Ascend hill and travel on middle Pleistocene hanging wall of the Escala fault (Connell piedmont deposits derived from the northern and Wells, 1999). 0.2 Sandia Mts. 0.9 75.0 Intersection with Quail Meadow Rd. Tunnel 71.3 The arroyo to the left, beyond house in Springs is visible at 11:00. It is the area that floodplain, exposes rounded quartzite and is marked by dense cottonwood vegetation, brown, cliff-forming sandstone and which contrasts with the surrounding Piñon- conglomerate of the ancestral Rio Grande Juniper woodland. 1.3 and piedmont deposits, respectively, of the 76.3 STOP 3: Tunnel Springs. Placitas 7.5’ Sierra Ladrones Fm. Piedmont deposits quadrangle, GPS: NAD 83, UTM Zone 013 contain limestone, granite, and sandstone S, N: 3,906,400 m; E: 369,080 m. derived from the Sandia Mountains. To the This is an overview stop of some stunning views east and stratigraphically above this fluvial of the northern flank of the Sandia Mts. and northern gravel in the arroyo are lenses of ancestral Albuquerque basin. Tunnel Springs emanates from Rio Grande deposits containing fluvially the Placitas fault zone. recycled pumice cobbles (not visible from The purposes of this stop are to: 1) discuss the road). One of these cobbles has been dated stratigraphy of the lower Santa Fe Group strata at 1.61±0.02 Ma (Connell et al., 1995) and is exposed in the Placitas area; 2) discuss the tectonic temporally correlative to the lower development of the northern flank of the Sandia Mts. Bandelier Tuff, which was derived from the and Santo Domingo sub-basin; and 3) discuss Jemez Mts. 0.8 previous models of development of the basin, 72.1 Homestead Village strip mall to your left. including the existence of the postulated Rio Grande Between 10:00 and 12:00 the northwest- fault. trending escarpment marks the Valley View The northern flank of the Sandia Mts. is a north- fault, which terminates to the south near the plunging structural ramp created by a 6.5-km wide Rincon fault (Connell et al., 1998). Within eastward step in the rift-bounding Rincon and San the next mile is the eastern projection of Francisco faults. A complicated zone of steep faults ancestral Rio Grande facies of the Sierra called the Placitas fault zone accommodates this step. Ladrones Fm, which is overlain by piedmont The origin of this step has created much controversy. deposits here. 0.5 Kelley (1977, 1982) considered this feature to be a 72.6 Rincon ridge is your right. 0.3 relay ramp associated with left-oblique movement 72.9 Milepost 3. Hills in the foreground are post- along the San Francisco and Rincon faults; however, Santa Fe Group middle Pleistocene gravels there is no strong evidence for transpression in this that overlie stream-flow dominated step over, which would be the likely result of a right piedmont sandstone and conglomerate of the step on a left-oblique fault system. Karlstrom et al. Sierra Ladrones Fm. 0.5 (1999), proposed that the Placitas fault zone 73.4 Las Placitas site marker. Low angle fault is represented an older, steeply dipping, northeast- part of Ranchos fault zone, which juxtaposes trending strike-slip fault of Laramide age that was Santa Fe Group deposits against Cretaceous reactivated during the . Paleomagnetic sandstone, shale, and coal. You have just studies of a single 30.9 Ma mafic dike in the Placitas crossed the border of the rift and are on the area (Connell et al., 1995) indicates that much of the northern flank of the Sandia Mts. 1.3 deformation post-dates emplacement of the dike 74.7 Pass intersection with Puesta del Sol Rd. (Lundahl and Geissman, 1999). It is likely that the 0.1 northern Sandia Mts. represents a breached relay 74.8 Turn right onto Tunnel Springs Rd. and ramp or transfer zone that formed during begin to ascend the Las Huertas surface. development of the Rincon and San Francisco faults. Deposits underlying this constructional The Santa Fe Group in the Placitas area contains piedmont surface unconformably overlie a record of early unroofing of the Sandia Mts. Along older tilted rocks and are inset against Overlook Rd. on the southern flank of Lomos Altos, undivided lower Santa Fe Group piedmont the Santa Fe Group is well cemented with sparry conglomerate and sandstone. The basal calcite and rests with angular unconformity on contact of these deposits has a slightly Cretaceous sandstone and shale. This section is unconformable relationship with underlying conglomeratic. The base contains abundant upper Santa Fe Group beds of the piedmont sandstone and minor limestone, most likely derived facies of the Sierra Ladrones Fm to the from the Glorieta and San Andres fms. Upsection the north, across the Escala fault; however, gravel is predominantly reddish-brown sandstone of

10 NMBMMR OFR 454A the Abo Fm. Near the top of the exposed section, Significant displacement of Cenozoic strata is gravel is predominantly limestone and cherty recognized in seismic-reflection lines and deep oil- limestone derived from the Pennsylvanian Madera test data near Isleta Pueblo (Russell and Snelson, Fm. At the southern tip of the Cuchilla de Escala, the 1994; May and Russell, 1994). Subsurface studies in composition of the Santa Fe Group gravel contains the Albuquerque area indicate that much of the Santa abundant rounded cobbles and pebbles of Fe Group strata thicken and tilt to the northeast porphyryitic intrusive rocks derived from the Ortiz (Connell et al., 1998a) and are not displaced across Mts. This gives way upsection to a mixture of the projected trace of the Rio Grande fault of Russell sandstone, limestone and Ortiz-derived rocks. and Snelson (1994). Geomorphic and stratigraphic The juxtaposition of these differing source areas studies along the northern flank do not support the indicates that during early development of the rift, presence of such a young and large magnitude sediment was being derived from both an emerging structure (Connell and Wells, 1999). Late Quaternary Sandia Mts., and a degrading (eroding) Ortiz Mts. movement of range-bounding faults of the Sandia The location of Ortiz-derived gravel also indicates Mts. indicates that faults along the eastern structural that the Cuchilla de San Francisco had not been margin of the Calabacillas sub-basin were active uplifted enough to affect the composition of the during Pleistocene time, at least locally (Connell, gravel, at least not initially. 1996). Another interesting unroofing sequence was Gravity data indicates that the basin-margin is recognized in the post-Santa Fe Group inset marked by a 2-3 km wide zone of normal faults that stratigraphy, where the topographically highest inset extend about 3-6 km west of the front of the Sandia gravels are composed almost exclusively of Mts. (Cordell, 1979; Grauch et al., 1999; Connell et limestone. On progressively inset deposits, the al., 1998a). The gravity data also suggest that Russell composition becomes more heterolithic, and granite and Snelson’s Rio Grande fault may be correlative and metamorphic rocks become more common in the with an older northwest-trending feature, rather than late Pleistocene and Holocene deposits associated a younger north-trending fault (Maldonado et al., with the modern valley floors that head into the 1999). This northwest-trending zone is called the northern flank of the Sandia Mts. This Plio- Mountainview fault to avoid confusion with Russell Pleistocene unroofing sequence is recorded in a and Snelson’s postulated Rio Grande fault. The deeply dissected geomorphic region, or domain, that Mountainview fault coincides with a northwest- is structurally defined by the Ranchos, Lomos, Escala trending gravity ridge (Grauch et al., 1999, this and Placitas faults (Connell and Wells, 1999). This volume) and likely marks the part of the structural geomorphic domain records progressive dissection boundary between the Calabacillas and Belen sub- along the northern flank of the Sandia Mts. that basins (Maldonado et al., 1999). Thus, the low-angle occurred in response to migration of the locus of fault shown described by Russell and Snelson (1994) faulting from the Placitas and southern San Francisco may the result of apparent dip of the northwest faults basinward to the Lomos, Escala, and Valley trending Mountainview fault, rather than a true dip of View faults, which probably started during late a low-angle fault. Pliocene time, prior to deposition of the gravel of The projected trace of the Rio Grande fault is Lomos Altos. buried by Plio-Pleistocene sediments and is west of a The Placitas area was interpreted to represent the prominent inflection in the isostatic gravity field surface expression of major listric faults that define (Cordell, 1979; Grauch et al. 1999). Geomorphic and the eastern basin margin. Woodward (1977) first stratigraphic evidence (Connell and Wells, 1999; proposed listric geometries for faults of the basin. Connell et al., 1998a) also indicate that the Rio These are recognized on seismic data (deVoogd et Grande fault is not a young intrabasinal normal fault. al., 1988; Russell and Snelson, 1994) and are Basin narrowing is recognized throughout the basin suggested by increasing tilts of basin-margin fault (Russell and Snelson, 1994), but is commonly blocks. This listric geometry is expressed on seismic restricted to prominent steps or re-entrants in the profiles along the southern margin of the basin. basin margin (Connell and Wells, 1999; Connell, Russell and Snelson (1994) propose that the 1996). At the northern flank of the Sandia Mts. is an Albuquerque Basin narrowed significantly between excellent example of such a step-over fault. The the late Miocene and Pliocene and that the range- Placitas fault zone accommodates slip across the bounding master faults of the Sandia Mts. were cut Rincon and San Francisco faults, and forms an east- by a younger intrabasinal listric-normal fault having stepping ramp (Connell and Wells, 1999; Connell et up to about 6 km of displacement of Cenozoic strata. al., 1995). Using the down-plunge method of cross They proposed that offset along this major section construction, several workers (Woodward and intrabasinal structure, which they named the Rio Menne; 1995; Russell and Snelson; 1994; May et al., Grande fault, began when the range-front master fault 1994) suggested that the trace of the Placitas fault migrated basinward about 15-20 km to the west. zone (northern structural boundary of the Sandia Mts.) is curved in map view. They interpreted

11 NMBMMR OFR 454A apparent curvature as indicative of a listric fault plane northern Sandia Mts. (upper Santa Fe Group). The at depth; however, the trace of the Placitas fault zone purposes of this stop are to: 1) examine ancestral Rio is rather straight (Connell et al., 1995), suggesting a Grande and piedmont members (or facies) of the steep dip. Furthermore, the down-plunge method may Sierra Ladrones Fm; 2) discuss ongoing studies of have been misapplied, principally because the deposit and lithologic differentiation of southward direction of projection is nearly the Sierra Ladrones and Arroyo Ojito fms in the perpendicular to the Placitas fault zone. Instead, the northern Albuquerque Basin; and 3) discuss evidence Placitas fault zone probably acts as a transfer zone of continuous aggradation of upper Santa Fe Group between the frontal faults of the Sandia Mts. and the deposits through late Pliocene-early Pleistocene time. San Francisco fault (Karlstrom et al., 1999). At this stop we will examine exposures of Plio- In summary, the Rio Grande fault concept of Pleistocene fluvial deposits of the ancestral Rio Russell and Snelson (1994) is not supported for the Grande system and interfingering piedmont deposits. following reasons: Ancestral Rio Grande deposits are gravelly with 1) Geomorphic evidence does not support the scattered rip-up clasts of mudstone (Fig. 1-8). The presence of a long, discrete intrabasinal fault ancestral Rio Grande fluvial system is documented to having a large magnitude of post-Miocene be at least 6.9 Ma, based on the presence of quartzite- displacement (Connell and Wells, 1999); bearing fluvial conglomeratic sandstone that was 2) Regional geophysical surveys (principally affected by the emplacement of the late Miocene isostatic residual gravity, and aeromagenetic Peralta Tuff, near Tent Rocks and Cochiti, New surveys) do not support the presence of a north- Mexico (Smith and Kuhle, 1998; Smith et al., 2001). trending intrabasinal fault zone (Grauch et al., Between Bernalillo and Tonque Arroyo, three facies 1999; Grauch, 1999); tracts can be seen: the western fluvial facies of the 3) Studies of borehole geophysics and cuttings from Arroyo Ojito Fm (Connell et al., 1999); the central numerous wells in the Albuquerque area identify axial-river facies of the ancestral Rio Grande, and marker units that are not displaced across the streamflow-dominated piedmont deposits derived projected trace of the Rio Grande fault (Connell from rift-margin uplifts, such as the Sandia Mts. et al., 1998a); and Geologic mapping indicates that the ancestral Rio 4) Stratigraphic data are inconsistent with the Grande member of the Sierra Ladrones Fm development of this structure (Connell and interfingers with the piedmont member. Wells, 1999; Maldonado et al., 1999). End of Stop 3. Retrace route to NM-165. 1.4 77.7 Turn left at stop sign onto NM-165. 2.2 79.9 At 3:00 in the hills covered by numerous houses on the footwall of the Valley View fault, notice interfingering of light-gray sand of the ancestral Rio Grande sands and light- brown piedmont deposits. You are near the eastern limit of the ancestral Rio Grande, as projected onto NM-165 (Connell et al., 1995). 2.6 82.5 Turn right on north frontage road. 0.2 82.7 Reddish-brown sandstone of the Loma Figure 1-8. Photograph of ancestral Rio Grande Barbon Mbr unconformably overlain by gravels in the La Farge gravel pit at Placitas Edith Fm. 0.2 (Bernalillo quadrangle). Note the mudstone rip-up 82.9 Turn right onto Yearsley Ave. Note the road clasts. The upper part of the outcrop is dumped fill cut on the adjacent road to the north (La from quarry operations. Mesa Rd). Here red east-tilted Loma Barbon deposits are interbedded with gray Rio These major, mappable lithofacies assemblages Grande sand and unconformably overlain by in the SE Santo Domingo and Calabacillas sub-basins quartzite gravels of the Edith Fm. 0.3 are the: western-margin facies, central ancestral Rio 83.2 Normal fault with down-to-the-east Grande facies, and the eastern-margin piedmont movement to your left. 0.4 facies. The western margin facies is the Arroyo Ojito 83.6 STOP 4: LaFarge gravel pit operation. Fm, which represents the fluvial facies of the Bernalillo 7.5’ quadrangle, GPS: NAD 83, ancestral Rio Puerco, Rio Jemez/Guadalupe, and Rio UTM Zone 013 S, N: 3,910,800 m, 362,837 San Jose. Sediments were probably derived from the m. Sierra Nacimiento, , and Deposits of the ancestral Rio Grande and Plateau to the west and northwest of the Albuquerque interfingering piedmont deposits derived from the basin. The ancestral Rio Grande lithofacies is part of

12 NMBMMR OFR 454A the Sierra Ladrones Fm and represents deposits of the 1998; Connell et al., 1995, 1998, 1999; Derrick, through-flowing axial-river system of the Rio unpubl. data) indicate that coarse-grained sediments Grande. The eastern piedmont facies is part of the of the Arroyo Ojito Fm flowed to the S-SE (Fig. 1- Sierra Ladrones Fm and contains detritus shed from 11a), ancestral Rio Grande deposits of the Sierra rift-flanking uplifts, such as the Sandia Mountains. Ladrones Fm flowed to the S-SW (Fig. 1-11b), and Large and Ingersoll (1997), in a study of sand eastern-margin piedmont deposits of the Sierra petrography in the northern part of the Albuquerque Ladrones Fm flowed to the west (Fig. 1-11c, d). Basin, concluded that deposits of the Santa Fe Group were not petrographically differentiable. A current study of gravel and sand composition (Derrick and Connell, 2001) indicates that these mapped facies are indeed differentiable, as discussed below. Preliminary results of point counts of pebbles and cobbles in the northern Albuquerque Basin (Fig. 1-9) indicate that the Arroyo Ojito Fm contains abundant volcanic tuffs and fine- to medium-grained red granites with lesser amounts of Pedernal , basalt, sandstone, and white quartzite. The ancestral Rio Grande member of the Sierra Ladrones Fm commonly contains rounded, bedded quartzites of various colors and diverse volcanic and intrusive rocks, including tan and gray tuffs, diabase, and granite. Sedimentary rocks are rare. The eastern piedmont deposits contain abundant limestone, sandstone, coarse-grained pink granite, and sparse igneous rocks. Sand composition from point counts of 400 grains per sample show that these mapped facies are not as easily differentiable as the gravel counterparts. The sand is quartz rich (46-85% quartz) and facies exhibit considerable compositional overlap when plotted using the modified Gazzi-Dickinson method. Compositional trends are observed when proportions of chert, granite, and volcanic grains are compared (Fig. 1-10). There is a stronger correlation among the lithofacies using gravel. Possible explanations for this correlation include the shorter transport distance of gravel from the source area, similar source areas for the ancestral Rio Puerco and the ancestral Rio Grande, or greater sediment recycling and transport of the finer-grained sand fraction. Near this stop, a series of stratigraphic sections Figure 1-9. Preliminary gravel petrography from were measured on San Felipe Pueblo that document selected localities in the SE Santo Domingo sub- the interaction of these facies from late Pliocene basin and Calabacillas sub-basin (N. Derrick, unpubl. through early Pleistocene time. In the Santo Domingo data). Rio Grande and piedmont samples are from the sub-basin, the Santa Fe Group experienced Sierra Ladrones Fm; western margin denotes samples continuous deposition prior to 2.2 Ma to younger from the Arroyo Ojito Fm. Abbreviations include than 1.6 Ma. Deposition of the system ceased as the quartz, quartzite, and chert (Q), sedimentary (S), Rio Grande began to incise into the basin fill. A volcanics (V), and plutonic-metamorphic (PM) fluvial terrace deposit containing the middle gravels. Pleistocene Creek B ash is inset against the basin fill, indicating that incision was underway End of Stop 4. Retrace route to frontage prior to ca. 0.66 Ma. road at entrance to gravel pit. 0.7 Paleocurrent data measured from gravel 84.3 At stop sign turn to your left, getting back imbrications, channel orientations, and cross beds for out onto the frontage road heading south. deposits in the southeastern Santo Domingo sub- 1.4 basin and Calabacillas sub-basin (Cather and Connell, 1998; Cather et al., 1997, 2000; Connell,

13 NMBMMR OFR 454A 85.7 At the intersection of the frontage road and NM-165, go straight, remaining on the frontage road heading south. 0.3 86.0 Light-brown middle Pleistocene sand and gravel overlie rounded quartzite-dominated gravel of the Edith Fm. 0.2 86.2 Entrance gate to reclaimed aggregate mine. Must get permission from owner to enter. Turn left. 0.3

Figure 1-11a. Paleocurrent rose for Arroyo Ojito Fm (western margin) deposits (at 10° intervals), including correlation coefficient (r). Data from Cather et al. (1997), Connell et al. (1999), Koning (unpubl.), and Derrick (unpubl.).

Figure 1-10. Preliminary sand petrography from selected localities in the SE Santo Domingo sub- basin and Calabacillas sub-basin (N. Derrick, unpubl. data). See Figure 1-9 for description of sample symbols. Plot of sand using modified Gazzi- Dickinson method (a); plot of major sand constituents Figure 1-11b. Paleocurrent rose for ancestral Rio (b). Grande deposits (at 10° intervals), including correlation coefficient (r). Data from Cather and Connell (1998), Cather et al. (2000), Connell (1998), Connell et al. (1995), and Derrick (unpubl.).

14 NMBMMR OFR 454A 86.5 STOP 5: Bernalillo 7.5’ quadrangle, GPS: NAD 83, UTM Zone 013 S, N: 3,908,060 m; E: 360,720 m. Inset stratigraphic relationships between aggradation of the Santa Fe Group and post-Santa Fe Group entrenchment (see mini paper by Connell and Love, this volume), including a buttress unconformity between the Edith Fm and piedmont deposits, with the Sierra Ladrones Fm. We will hike eastward, up an unnamed arroyo to examine the inset stratigraphic relationship of a middle Pleistocene fluvial deposit of the ancestral Rio Grande called the Edith Fm. The purposes of this stop are to: 1) examine the Edith Fm and its basal strath with underlying upper Santa Fe Group strata; 2) examine a buttress unconformity between the Edith Fm and the Santa Fe Group; and 3) discuss the timing of entrenchment of the basin fill and development of the Rio Grande Valley. The gravel quarry is surface mining the quartzite-bearing cobble and pebble gravel of the base of the Edith Fm. This coarse gravel commonly lies on fluvial deposits of the Sierra Ladrones Fm or Arroyo Ojito Fm with slight angularity. The gravel Figure 1-11c. Paleocurrent rose for younger eastern- fines up into sand, which commonly forms an upward margin piedmont deposits (Sierra Ladrones Fm, at fining sequence with a locally preserved weakly 10° intervals), including correlation coefficient (r). developed soil. The Edith Fm is overlain by middle Data from Cather and Connell (1998), Connell et al. to late Pleistocene gravel and sand derived from the (1995), and Derrick (unpubl.). Sandia Mts. As we travel upstream, the Edith Fm is buried. About 1 km to the east is a buried paleobluff cut by the Edith Fm. The piedmont deposits formed a valley border fan that eventually buried this bluff. The rounded gravels in the tilted Santa Fe Group are thin beds of ancestral Rio Grande deposits, which extend ~2.4 km to the east, where it occupied a proximal position to the mountain front until early Pleistocene time.

Retrace route back to NM-165. End of first-day road log.

Figure 1-11d. Paleocurrent rose for older eastern- margin piedmont deposits (Santa Fe Group, at 10° intervals), including correlation coefficient (r). Data from Connell et al. (1995).

15 GEOLOGICAL SOCIETY OF AMERICA, ROCKY MOUNTAIN-SOUTH CENTRAL SECTION MEETING, ALBUQUERQUE, NEW MEXICO PRE-MEETING FIELD TRIP: STRATIGRAPHY AND TECTONIC DEVELOPMENT OF THE ALBUQUERQUE BASIN, CENTRAL Rio Grande RIFT

SECOND-DAY ROAD LOG, APRIL 28, 2001 CALABACILLAS SUB-BASIN: ZIA PUEBLO, RIO RANCHO, AND TIJERAS ARROYO

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

DANIEL J. KONING Consulting geologist, 14193 Henderson Dr., Rancho Cucamonga, CA 91739

NATHALIE N. DERRICK Dept. of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801

DAVID W. LOVE New Mexico Bureau of Mines and Mineral Resources, 801 Leroy Place, Socorro, NM 87801

SPENCER G. LUCAS New Mexico Museum of Natural History and Science, 1801 Mountain Road N.W., Albuquerque, NM 87104

GARY S. MORGAN New Mexico Museum of Natural History and Science, 1801 Mountain Road N.W., Albuquerque, NM 87104

PATRICIA B. JACKSON-PAUL New Mexico Bureau of Mines and Mineral Resources- Albuquerque Office, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

The following road log through parts of the Calabacillas sub-basin (Figs. 2-1, 2-2) has been summarized from New Mexico Geological Society Guidebook 50 (Pazzaglia et al., 1999a) and from Hawley and Galusha (1978). Road-log mileage not checked for accuracy.

Mileage Description Ascend terrace riser between Los Start, parking lot of Sheraton Hotel. Duranes and Lomatas Negras fms. The Road log follows Day 1 log to Bernalillo. Lomatas Negras Fm is a high-level 0.0 Leave I-25 at exit 242 to US-550 and terrace gravel approximately 70-80 m NM-165. above the Rio Grande (Connell, 1998). 0.3 Turn left at stop light and proceed The geomorphic term tercero alto is an towards Bernalillo. 0.3 informal term applied by Machette 0.6 Railroad crossing cut into alluvial fan (1985) to these gravels. Connell and that overlies valley-floor alluvium of the Love (2000; and this volume) suggested Rio Grande valley, which are ~25 m the Lomatas Negras Fm as a lithologic thick (Connell, 1998). 0.3 (rather than geomorphic) term for these 0.9 Intersection with Camino del Pueblo. 0.7 deposits, which are inset against the 1.6 East bank of the Rio Grande. Cross the constructional basin-floor surface of the Rio Grande and riparian in the Llano de Albuquerque (Machette, 1985) floodplain. Gravel along the west bank of represents an abandoned constructional the Rio Grande, overlying reddish-brown surface that marks the highest level of sandstone and mudstone of the Arroyo basin aggradation in the Santa Fe Group Ojito Fm, are correlated to the Los west of the Rio Grande, and represents a Duranes Fm (Connell, 1998). 0.7 local top of the Santa Fe Group. 2.3 Santa Ana Casino on your right. Road to Jemez Canyon Dam to your right.

17 NMBMMR OFR 454A

Figure 2-1. Shaded-relief map of the Albuquerque area, illustrating the locations of stops for day 1 (black circles), and day 2 (white squares). Base prepared by S.D. Connell for Pazzaglia et al. (1999b).

18 NMBMMR OFR 454A

Figure 2-2. Simplified geologic map of the NW margin of the Calabacillas sub-basin, illustrating the approximate location of stops 1-6.

To the south, correlative deposits contain ridge less than 2 km to the northeast the middle Pleistocene Lava Creek B ash yields a 40Ar/39Ar date (on sanidine) of (ca. 0.66 Ma; N. Dunbar, 2000, written 6.82±0.04 Ma (Connell, 1998) and is commun., A. Sarna-Wojciki, 2001, geochemically correlative to the Peralta written commun.). The maximum Tuff Mbr of the Bearhead Rhyolite, vertical extent of incision by the Rio exposed at Tent Rocks and Peralta Grande during the Pleistocene is Canyon in the western Santo Domingo approximately 100-200 m. 0.3 sub-basin (N. Dunbar, oral commun., 2.6 Intersection with NM-528. 0.5 2001). A number of lapilli and ash fall 3.1 Milepost 3. Ascend terrace riser between deposits in similar stratigraphic positions Los Duranes and Lomatas Negras fms. are exposed along the southern margin of 1.0 the Rio Jemez valley. These tephra are 4.1 Milepost 4. 0.4 dated between 6.8-7.4 Ma (W.C. 4.5 Loma Barbon Mbr offset down-to-the- McIntosh, 1998-2000, written commun.). east by the Luce fault of Kelley (1977) in Similar-aged fall deposits have not been road cut to your right. 2.1 recognized to the south in the Arroyo 6.6 at 9:00 expose the Loma Ojito Fm, suggesting that these Barbon Mbr of the Arroyo Ojito Fm, exposures may be near the southern limit which are capped by conglomeratic sand of fallout from the Bearhead vents. 0.5 of the Ceja Mbr of the Arroyo Ojito Fm 7.1 Milepost 7. Sierra Nacimiento at 11:00 beneath the Llano de Albuquerque. and the eastern flank of the Ziana Loma Barbon is low hill between 9- structure between 9:00 and 10:00. The 10:00. A volcanic ash exposed on a Ziana structure is interpreted to be a

19 NMBMMR OFR 454A horst by Personius et al. (2000, see cross southern Rocky Mts. are between 11:00 section), or an anticlinal accommodation and 3:00. The high peak at 2:00 is zone (Stewart et al., 1998) that marks the Pajarito Peak of the Sierra Nacimiento. boundary between the Calabacillas and Rio Jemez valley incised through an Santo Domingo sub-basins. The southern ignimbrite sheet of the upper Bandelier flank of the Jemez Mts at 1:00-3:00. An Tuff (ca. 1.2 Ma) and Permian sandstone angular unconformity between at 3:00. The white cliffs between 12:00 Quaternary alluvial deposits and dipping and 1:00 are underlain by gypsum of the sediments of the Arroyo Ojito and Zia Todilto Fm, which is being quarried fms are visible. 0.5 here. 1.0 7.6 Santa Ana Pueblo reservation boundary. 18.9 Low hills to left are underlain by Volcanic rocks and Santa Fe Group Chamisa Mesa Mbr of Zia Fm. 1.1 sediments are exposed at the southern 20.0 Approaching western boundary of the flank of the Jemez Mts between 1-3:00. rift. Jurassic and Cretaceous rocks ahead. From left to right is Chamisa Mesa, Jemez valley at 3:00. 1.0 capped by the 10.4±0.5 Ma basalt at 21.0 Turn left onto Cabezon Rd. and stay Chamisa Mesa (K/Ar date in Luedke and straight, passing onto Zia Pueblo land. Smith, 1978). The Chamisa Mesa basalt The following stop is on Zia Pueblo land. (Paliza Cyn Fm) overlies the Cerro You must obtain permission to travel Conejo and Chamisa Mesa Mbrs of the on Zia tribal lands from the Pueblo Zia Fm. Other late Miocene basaltic administration. 1.1 features of the Paliza Cyn Fm include 21.1 Bear right, stay on Cabezon Rd. Borrego Mesa, Pico Butte, and Bodega Traveling on pre-rift rocks of the Butte. 1.1 and San Juan Basin. 8.7 White bed to your left is an ash Road traverses Jurassic strata of the correlated to one of the Trapper Creek Summerville and Todilto Fms to your tephra. 0.4 right, and Brushy Basin Mbr of the 9.1 Cross valley incised into the Cerro Morrison Fm to your left. Cross north- Conejo Mbr with at least two prominent striking, down-to-the-east San Ysidro white ashes exposed between 9:00 and fault (Woodward and Ruetschilling, 10:00. The thicker ash bed has been 1976). To the north, it places geochemically correlated (A. Sarna- rocks against Neogene Wojcicki, written commun., 1999, 2001) basin fill. To the south, it places Zia Fm to Snake River Plain/Yellowstone tephra against the Arroyo Ojito Fm. This fault from the Trapper Creek section of shows evidence of Pliocene and possible southern . Age estimate of the best early Quaternary displacement exposed match is 11.2±0.1 Ma and a weaker along La Ceja, the southern margin of match to a higher tephra in the same the Rio Puerco valley and northern limit section was correlated to tephra dated at of the Llano de Albuquerque. 1.4 10.94±0.03 Ma by Perkins et al. (1998). 22.5 Pass narrows through the Salt Wash Mbr The ~11 Ma age of this ash agrees well of the Morrison Fm 1.5 with the presence of the Clarendonian 24.0 Turn left on unmarked dirt road. 0.9 canid , which was obtained near 24.9 Gray cliffs on your left are Piedra Parada here (Lucas and Morgan, this volume; Mbr deposits of the Zia Fm overlying the R.H. Tedford, 1999, oral commun.). 0.8 Galisteo (Eocene) and Menefee 9.9 To your right, note outcrop of ledgy, (Cretaceous) fms. On your right is cemented sandstone beds in the Cerro Cretaceous Mancos Shale. 1.1 Conejo Mbr of the Zia Fm with oriented 26.0 Bear right. 0.5 concretions (see Mozley and Davis, 26.5 Pull off road into field and park. Hike up 1996; Beckner and Mozley, 1998). 1.2 hill to outcrop. STOP 1. The Zia Fm 11.1 Milepost 11. 2.2 and base of syn-rift sediments. Cerro 13.3 Zia Pueblo reservation boundary. 2.2 Conejo (formerly Sky Village NE) 7.5’ 17.9 Entrance to Zia Pueblo at 3:00. The quadrangle, GPS: NAD 83, UTM Zone Pueblo sits atop a middle Pleistocene 013 S, N: 3,926,640 m; E: 334,515 m. terrace tread (Qt4 of Formento-Trigilio The purpose of this stop is to observe the contact and Pazzaglia, 1998) north of the Rio between pre- and syn-rift rocks and discuss the Jemez. The western flank of the Rio sedimentology, paleo-environmental, and structural Grande rift, eastern margin of the setting of the Zia Fm. Colorado Plateau, and southern tip of the

20 NMBMMR OFR 454A We will examine exposures of the type Piedra Parada Mbr of the Zia Fm, which rests upon upper Galisteo Fm mudstone and conglomerate. The basal 0.5-3 m of the Zia section in Arroyo Piedra Parada contains fluviatile gravel composed mostly of rounded chert pebbles derived from rocks of the Colorado Plateau. Scattered within the gravel are cobbles of rounded, intermediate volcanic rocks (Fig. 2-2). Elsewhere, these cobbles form a discontinuous stone pavement, where many of the volcanic clasts have been sculpted by the wind into ventifacts (Tedford and Barghoorn, 1999; Gawne, 1981). Three volcanic clasts have been 40Ar/39Ar dated between 32 to 33 Ma (31.8±1.8 Ma, 33.03±0.22 Ma, 33.24±0.24 Ma, S.M. Cather, W.C. McIntosh, unpubl. data), indicating that they were once part of the middle Tertiary volcaniclastic succession. The dates alone are not sufficient to established correlation to possible Oligocene sources, such as the , Mogollon-Datil volcanic field, or the Ortiz porphyry belt. The clasts could be derived from the now buried unit of Isleta #2 of Lozinsky (1994), which approaches 2.2 km thickness in oil-test wells about 25-30 km to the south.

21 GEOLOGICAL SOCIETY OF AMERICA, ROCKY MOUNTAIN-SOUTH CENTRAL SECTION MEETING

PRE-MEETING FIELD TRIP: STRATIGRAPHY AND TECTONIC DEVELOPMENT OF THE ALBUQUERQUE BASIN, CENTRAL RIO GRANDE RIFT

THIRD-DAY ROAD LOG, APRIL 29, 2001 BELEN SUB-BASIN: BELEN, SEVILLETA NATIONAL WILDLIFE REFUGE, AND NORTHERN SOCORRO BASIN

DAVID W. LOVE New Mexico Bureau of Mines and Mineral Resources, 801 Leroy Place, Socorro, NM 87801

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

SPENCER G. LUCAS New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104

GARY S. MORGAN New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, NM 87104

NATHALIE N. DERRICK Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801

PATRICIA B. JACKSON-PAUL New Mexico Bureau of Mines and Mineral Resources- Albuquerque Office, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

RICHARD CHAMBERLIN New Mexico Bureau of Mines and Mineral Resources, 801 Leroy Place, Socorro, NM 87801

The following road log is summarized and modified from Hawley (1978). Road-log mileage not checked for accuracy.

Mileage Description nearly flat constructional surface that 0.0 Load vehicles in front of Sheraton Old locally marks the top of the upper Santa Town. Turn left onto Bellamah Road Fe Group. This surface was called the (north of hotel) and reset odometer at Sunport surface by Lambert (1968) for intersection of Bellamah and Rio the airport. To the left are pinkish- Grande Blvd. Turn south (left) on Rio orange arkosic sediments that are Grande Blvd. 0.2 derived from the ancestral Tijeras Creek 0.2 Turn east on Central Ave. 0.3 and upper Santa Fe Group strata along 0.5 Turn left on Lomas Blvd. 1.5 the eastern margin of the Rio Grande 2.0 Cross Broadway and begin ascent of valley. 2.6 Holocene to latest Pleistocene valley 7.2 Rio Bravo Blvd. overpass (exit 220). border fan surfaces. 0.1 Exposures to left are light-brown sand 2.1 Cross Edith Blvd. 0.3 and gravel of the Arroyo Ojito Fm, 2.4 Turn right on south Frontage Road. 0.4 overlain by light-gray sand and gravel 2.8 Cross Martin Luther King Blvd. 0.2 of the ancestral Rio Grande facies of the 3.0 Cross Central Ave. and ascend onramp Sierra Ladrones Fm, which contains to southbound I-25. 1.6 abundant pumice gravel derived from 4.6 Gibson Blvd. overpass. Albuquerque the Cerro Toledo Rhyolite and International Airport on high surface to Bandelier Tuff from the Jemez Mts. 0.8 your left. The airport is constructed on a

27 NMBMMR OFR 454A

8.0 Overpass of abandoned railroad and Irvingtonian) vertebrates (e.g., location of Day 2, Stop 5. Descending and horse) from the ancestral Rio into Tijeras Arroyo, which drains an Grande sediments near the top of the area of Proterozoic, , and exposures along the margins of Tijeras Mesozoic rocks within and east of the Arroyo. The top of the erosional scarp Sandia and Manzanita Mts. The on the south side of Tijeras Arroyo east arroyo’s course through the mountains of I-25 is a remarkably flat and weakly is in a deep canyon that follows the dissected surface that is a northward Tijeras fault in places. The Arroyo Ojito extension of the piedmont plain west of Fm underlies hills bordering both sides the Manzano Mts. (Llano de Manzano of the mouth of Tijeras Arroyo. Kelley of Machette, 1985). 0.4 (1977) proposed the term Ceja Mbr 8.4 Milepost 219. Bridge over Tijeras (Santa Fe Fm) to designate the upper, Arroyo. Begin ascent out of Tijeras gravelly part of the upper buff member Arroyo. Exposures along I-25 are of Bryan and McCann (1937) and underlain by Arroyo Ojito Fm sand and Lambert (1968). However recent gravel and partially covered by alluvial mapping has differentiated the Arroyo deposits derived from the overlying Rio Ojito Fm from an overlying ancestral Grande deposits east of the abandoned Rio Grande facies of the Sierra landfills along the southern margin of Ladrones Fm (Connell et al., 1998b). Tijeras Arroyo and near the crest of the Lambert (1968) and Lucas et al. (1993) hills east of I-25 for the next mile. 4.1 reported early Pleistocene (early

ELEVATIONS OF GEOLOGIC FEATURES, PAJARITO GRANT, LOS PADILLAS, AND MESA DEL SOL, BETWEEN I-25 MILE POSTS 216 AND 217 Elevations are in feet above mean sea level as measured from USGS 7.5-minute topographic maps. Arrows point to described features and elevations to your left (east) and right (west) in decreasing order of elevation. EAST WEST Å 5490 base of Hubbell Spring fault scarp, Sandia National Labs/Kirtland AFB east edge of Llano de Albuquerque (Pajarito) 5410 Æ top of Isleta volcano (3 km south) 5387 Æ Å 5331 Top of Mesa del Sol Å 5325 Top of Rio Grande gravel with Upper Bandelier Tuff boulders Å 5305 Surface at top of 1650-foot Mesa del Sol well Å 5290 Base of Rio Grande gravelly sand capping Mesa del Sol Å 5170 Pliocene pumice (chemically correlated to NW and SW) under Mesa del Sol Å 5160 Pliocene Hawaiite tephra in section top of Rio Grande upper terrace gravel 5160 Æ Lava Creek B ash in gravel terrace ~ 5050 Æ top of Black Mesa lava flow 5060 (west) to 5029 (east) Æ base of Black Mesa lava flow 5050 (west) to 4990 (east) Æ base of upper gravel terrace complex 5030 Æ base of Rio Grande lower gravel terrace 4980 Æ Å 4910 base of Pliocene exposures of Arroyo Ojito Fm Å 4895-4905 Rio Grande flood plainÆ Å 4900 Rio Grande floodway channel Æ Å 4825 base of Rio Grande paleovalley Æ

12.5 Exit 215, NM-47 (South Broadway). 12.6 Bridge over Burlington Northern-Santa Road descends Holocene alluvial-fan Fe Railroad. 0.3 apron to river floodplain and exposures 12.9 East abutment of I-25 bridge over Rio of a down-to-the-east fault zone in the Grande. Rio Grande channel ahead. 0.4 underlying Santa Fe Group. The Arroyo 13.3 Milepost 214. West bridge abutment. Ojito Fm underlies scarp east of the 0.5 floodplain. 0.1 13.8 Crossing Isleta Blvd. 0.3

28 NMBMMR OFR 454A

14.1 Entering Isleta Pueblo. Overpass of Black Mesa. Roadcut to right shows the drain and location of Isleta-Black Mesa edge of the 2.68±0.04 Ma (40Ar/39Ar, piezometer, which encountered 73 ft Maldonado et al., 1999) Black Mesa (22 m) of sandy fluvial deposits flow overlying cross-bedded pebbly underlying the Rio Grande floodplain sands of the Arroyo Ojito Fm and base- (Los Padillas Fm of Connell and Love, surge deposits from Isleta volcano. The this volume). Deposits are associated tholeiitic Black Mesa flow has no with the last incision/aggradation outcrop connection with, and is slightly episode of the Rio Grande. Incision younger than, Isleta volcano, which probably occurred during latest- forms the dark, rounded hill ahead and Pleistocene time, and entrenched 100 m to the right of the highway. A buried below the highest inset terrace deposit vent for the Black Mesa flow is of the Lomatas Negras Fm. 0.6 suspected in the floodplain area to the 14.7 Crossing bridge over Old Coors Road, northeast (Kelley et al., 1976; Kelley which follows a former course of the and Kudo, 1978). 0.3 Rio Grande cut through the lava flow of

ELEVATIONS OF GEOLOGIC FEATURES, WIND MESA, ISLETA, MESA DEL SOL (SOUTH), BETWEEN I-25 MILE POSTS 212 AND 210 Elevations are in feet above mean sea level as measured from USGS 7.5-minute topographic maps Arrows point to described features and elevations to your left (east) and right (west) in decreasing order of elevation. EAST WEST top of east horst of Wind Mesa 5730Æ “bath-tub ring” of gravel, east side of Wind Mesa 5500 Æ top of Isleta volcano 5387 Æ Å 5340 base of Western Hubbell Spring fault scarp Å 5240 top of Mesa del Sol east edge of Llano de Albuquerque (down-faulted block) 5240 Æ Å 5230 top of gravel with Bandelier boulders Å 5210 base of Rio Grande gravelly sand capping Mesa del Sol Å 5205 tilted Arroyo Ojito Fm under Mesa del Sol containing Pliocene pumice Å 5195 Pliocene Isleta (?) basaltic tephra in Arroyo Ojito Fm Å 5130 local top of Pliocene thick reddish-brown sandy clay of Arroyo Ojito Fm top of upper terrrace gravel west of Isleta volcano 5100 Æ Å 5050 base of thick reddish-brown clay (Pliocene) of the Arroyo Ojito Fm upper edge of lava lake within tuff ring 5050 Æ top of Los Duranes Fm 5020 Æ Å 4960 Pliocene pumice gravel top of Rio Grande terrace inset against Isleta volcano 5000 Æ basaltic edifice southeast of Isleta volcano with strath terrace at top 4910-4970 Æ base of Rio Grande terrace inset against Isleta volcano 4910 Æ Å 4910 Pliocene pumice gravel Base of lava flow east of Highway 85, 4900 Æ Å 4885 Isleta (?) tephra 4895 Æ Å 4892 Pliocene pumice gravel Å 4890 Rio Grande flood plainÆ Å 4885 Rio Grande floodway channel Æ Å 4805 base of Rio Grande paleovalley Æ

15.0 Base-surge deposits of tuff cone on right. Overlying alkali-olivine basalt associated with emplacement of Isleta flows fill tuff ring and extend southeast volcano in outcrops on both sides of beyond Isleta volcano. Radioisotopic route. 0.5 dates (40Ar/39Ar method) indicate that 15.5 Change in primary dip direction of oldest flow is 2.75±0.03 Ma and the base-surge deposits at crest of tuff ring second is 2.78±0.06 Ma (Maldonado et

29 NMBMMR OFR 454A

al., 1999). Basaltic cinders correlated to side of the valley have experienced the Isleta volcano flows are recognized over 100 m of uplift with consequent in the Arroyo Ojito Fm exposed along erosion of the overlying units before the eastern margin of the Rio Grande final deposition by the Rio Grande to valley. These cinder-bearing deposits form the Sunport Surface. Because are about 75-100 m (estimated) early Pleistocene terraces of the Rio stratigraphically below exposures of Grande pass west of Isleta volcano at Pleistocene, Bandelier-Tuff bearing high levels, the volcanic edifice sand and gravel of the ancestral Rio probably was exhumed during middle Grande facies of the Sierra Ladrones and late Pleistocene time (see mini- Fm. This stratigraphic relationship paper by Love et al., this volume). 0.1 indicates that deposition of the Arroyo 15.6 Entering cut exposing basalt flow of Ojito Fm continued after 2.72-2.78 Ma, Isleta volcano over tuff unit. Shell thereby constraining the age of the Isleta #2 well is about 1 mi. to the west, mesa capping Llano de Albuquerque to where it reached a depth of 6482 m and between 2.7 to 1.6 Ma or 1.2 Ma. ended in Eocene rocks. Lozinsky Based on local stratigraphy on both (1994) reports that the Santa Fe Group sides of the present valley, it is likely is 4407 m thick at the Isleta #2 well and that the Llano de Albuquerque was is underlain by 1787 m of the Eocene- abandoned as an active fluvial fan prior Oligocene unit of Isleta #2, which to deposition of Lower Bandelier ash overlies more than 288 m of sediments and pumice gravel at ca. 1.6 Ma. correlated with the Eocene Baca or Locally, the cinder deposits on the east Galisteo fms. 1.8

ELEVATIONS OF GEOLOGIC FEATURES, SAN CLEMENTE TO LOWER HELL CANYON, BETWEEN I-25 MILE POSTS 205 AND 206 Elevations are in feet above mean sea level as measured from USGS 7.5-minute topographic maps Arrows point to described features and elevations to your left (east) and right (west) in decreasing order of elevation. EAST WEST

base of 100,000--old basalt flow 1 of Cat Mesa resting on top of San Clemente graben fill 5315 Æ Å 5310 top of eastern piedmont aggradation, footwall of western Hubbell Spring fault Lower (?) Bandelier pumice in cross-bedded sand, San Clemente graben 5300 Æ Å 5280 Lower Bandelier pumice in ancestral Rio Grande unit, footwall of western Hubbell Spring fault encroaching piedmont from Los Lunas volcano on graben-fill (1.1 km south) 5280 Æ Los Lunas volcano tephra (<1.2 Ma) at top of San Clemente section (2.2 km SE) 5260 Æ Å 5260 top of ancestral Rio Grande deposits bearing Upper Bandelier boulders, north side of Hell Canyon Blancan fossil camel bones in section tilted 6 degrees SW, east of San Clemente graben 5240 Æ thick soil at base of San Clemente graben section 5220 Æ pumice similar to 3 Ma pumice in tilted section, east of San Clemente graben 5215 Æ Å 5140 top of Rio Grande gravel east of Palace-Pipeline fault, south of Hell Canyon Å 5100 top of Rio Grande gravel west of Palace-Pipeline fault Å 5065 top of Hell Canyon gravel and soil, mouth of Hell Canyon Å 5060 top of Rio Grande gravel in section at mouth of Hell Canyon Å 5000 Cerro Toledo (c.a. 1.5 Ma) ash in Janet Slate section , mouth of Hell Canyon top of Los Duranes Fm 4985 Æ

Å4915 base of exposures of ancestral Rio Grande with pre-Bandelier pumice and ash Å 4865 Rio Grande floodplain Æ Å 4863 Rio Grande floodway channel Æ

17.4 Exit 209 overpass to Isleta Pueblo. Road deposit of the ancestral Rio Grande now on upper constructional surface of named by Lambert (1968) for exposures the Los Duranes Fm, a middle to in NW Albuquerque. The Los Duranes upper(?) Pleistocene inset fluvial Fm is inset against middle Pleistocene

30 NMBMMR OFR 454A

fluvial deposits correlated to the near San Clemente are deformed into a Lomatas Negras Fm, which contains an flat-floored syncline. At least 37 m of ash that was geochemically correlated to fine sand, silt, and clay with a few the 0.60-0.66 Ma Lava Creek B ash, coarser pebbly sand units accumulated from the Yellowstone area in Wyoming in this graben where we found a bed of (N. Dunbar, 2000, written commun,; A. fluvially recycled pumice pebbles about Sarna-Wojcicki, 2001, written 29 m above the base of the graben-fill commun.). At 3:00 is a low dark hill of section. A pumice pebble has been the 4.01±0.16 Ma Wind Mesa volcano geochemically correlated to the (Maldonado et al., 1999). The late Bandelier Tuff (probably lower BT Pleistocene Cat Hill volcanoes between based on stratigraphic relationships at 2:00-3:00. Hell Canyon Wash is at 9:00 Los Lunas volcano). Farther south, near on the eastern margin of the Rio Grande NM-6, tephra from Los Lunas volcano Valley. 1.1 (ca. 1.2 Ma) overlies correlative graben- 18.5 Railroad overpass. A soil described in fill sediments, which lie only a few exposures of the uppermost Los meters above a stage III soil that is Duranes Fm indicate that soils are interpreted to mark a break in weakly developed with Stage I and II+ deposition of the Arroyo Ojito Fm pedogenic carbonate morphology (S.D. along the easternmost edge of the Llano Connell, and D.W. Love, unpubl. data). de Albuquerque. 1.1 0.8 22.4 Southern boundary of Isleta 19.3 Milepost 208. Between 1:00-2:00 is the Reservation. El Cerro de Los Lunas rift-bounding uplift of Mesa Lucero, between 1:00-2:00. Northwest of the which is about 30 km west of here. 0.6 volcano, northwest-tilted beds of the 19.9 Valencia County Line. 0.4 Arroyo Ojito Fm contain multiple layers 20.3 Milepost 207. Late Pleistocene basalt of pumice pebbles. A pumice pebble flow of the Cat Hills volcanic field collected in the middle of the section of overlies the Los Duranes Fm at 3:00. the Arroyo Ojito Fm here has been This flow is the oldest of the Cat Hills geochemically correlated to a pumice seven flows and yielded two 40Ar/39Ar unit which was 40Ar/39Ar dated at dates of 98±20 ka and 110±30 ka 3.12±0.10 Ma in the Arroyo Ojito Fm (Maldonado et al., 1999). The exposed beneath the Llano de Albuquerque volcanoes (dated using Albuquerque in the valley of the Rio 238U/230Th method at 156±29 ka, Peate Puerco on the Dalies NW quadrangle et al., 1996) overlie the Lomatas Negras (Maldonado et al, 1999). This pumice Fm and locally interfinger with the top has been geochemically correlated to a of the Los Duranes Fm in NW pumice pebble at Day 1, Stop 7 in Rio Albuquerque. These dates constrain the Rancho. 0.7 upper limit of deposition of this 23.1 Borrow pit to right exposes weakly extensive terrace deposit to between 98- developed soil in Los Duranes Fm. 0.8 156 ka, which spans the boundary of 23.9 Overpass of NM-6 to Los Lunas exit marine oxygen isotope stages (MOIS) 5 (Exit 203). El Cerro de Los Lunas and 6 (Morrison, 1991). These dates consists of several eruptive centers of and stratigraphic constraints indicate to . The earliest that much of the deposition of the Los eruption consisted of andesitic and Duranes Fm occurred prior to the dacitic vent breccias and lava flows that interglacial MOIS 5. 1.0 have an 40Ar/39Ar age of 3.88±0.01 Ma 21.3 Milepost 206. Descend possible fault (Panter et al., 1999). The north edifice scarp in Los Duranes Fm. Beneath rim with the “LL” on it is a trachyandesite of Cat Hills lava flows about 6 km (4 with an 40Ar/39Ar age of 1.22±0.01 Ma mi.) west of here is the San Clemente (Panter et al., 1999). A separate, graben. It extends northward from near undated vent at the top of the mountain Los Lunas volcano to a graben that produced red and gray scoraceous splits Wind Mesa (Maldonado et al., tephra that extended for several km2 to 1999). The Arroyo Ojito beds and thick the north, east and southeast of the stage III soil beneath the graben-fill volcano. The underlying flow and

31 NMBMMR OFR 454A

scoria were then cut by several north- V. Grauch (personal commun., 1999) south faults. The scoria vent, underlying suggests that the magnetic polarity of flow, and Santa Fe Group strata were these flows is reversed, indicating that tilted and uplifted more than 100 m they predate the Brunhes chron (older above the surrounding landscape and than 780 ka). 1.3 rapidly eroded, forming a piedmont 25.2 Milepost 202. At 3:00, north-south apron to the west and northwest. An faults cut flows and are overlain by eroded fault scarp on the east side of the more flows of Los Lunas volcano. 1.0 peak has dip-separation of 43 m on the 26.2 Milepost 201. Older flows of Los Lunas 1.2 Ma flow. The next set of eruptions volcano at 3:00-4:00. El Cerro Tomé issued along the fault scarp and buried across valley at 11:00-12:00 is small talus from the scarp. Between eruptions, andesitic volcanic center. Bachman and minor amounts of talus and eolian sand Mehnert (1978) report a K/Ar age of buried the lava flows. The final vent 3.4±0.4 Ma from a plug from this produced at least three lava flows that center. descended eastward toward the valley.

ELEVATIONS OF GEOLOGIC FEATURES, DALIES, LOS LUNAS VOLCANO, LOS LUNAS, AND MEADOW LAKE, BETWEEN I-25 MILE POSTS 202 AND 203 Elevations are in feet above mean sea level as measured from USGS 7.5-minute topographic maps Arrows point to described features and elevations to your left (east) and right (west) in decreasing order of elevation.

EAST WEST top of Los Lunas Volcano main edifice 5955 Æ base of 1.2 Ma flow west of edifice fault ~5760 Æ begin piedmont slope to west and northwest for 4.4 km to 5280 near Sandia siding 5740 Æ base of 1.2 Ma flow east of edifice fault 5620 Æ tilted 3.1 Ma pumice in section beneath uplifted volcano 5510 Æ 1.2 Ma Tschirege ash in paleovalley with boulders of 1.2 Ma lava, base of piedmont 5500 Æ Dalies railroad junction resting on Llano de Albuquerque soil 5305 Æ base of Los Lunas tephra in syncline, base of volcanic piedmont 5290 Æ base of 1.2 Ma flow beneath falls, northeast edge ~5140 Æ Å 5110 top of Rio Grande deposits at western edge of Meadow Lake base of southeast flow lobes 5100 Æ Å5050 faulted (?) bench at top of Rio Grande deposits east of Los Lunas base of younger flow, straight bluff below round eastern lobe 5050 Æ top of Los Duranes Fm 4950 Æ Å 4845 Rio Grande floodplain Æ Å 4840 modern channel of Rio Grande, southern Los Lunas Æ Å 4770 base of Rio Grande paleovalley Æ

The northern Manzano Mts. (Reiche, faulted to the west along the range- 1949) form the skyline between 9:00- bounding Manzano fault. Basin-fill 12:00. Magdalena Mts. at 12:00-1:00, thickness increases abruptly west of the and the Ladron Mts. are at 1:00. The scarp. Kelley (1977) inferred some north-south-trending break in slope movement along the 135-ft (40-m) high from midway up the Llano de Manzano scarp in Holocene time; however, to the Manzano Mts. is the scarp of the Machette et al. (1998) summarize Hubbell Spring fault zone (Maldonado investigations and conclude that the et al., 1999), which marks the western latest movement on the Hubbell Spring edge of the Joyita-Hubbell bench of fault zone is late Pleistocene in age. Kelley (1977). This structural bench is About 1 mi. east of this point is the up-thrown on the east and is formed on Harlan and others #1 exploratory well. pre-rift Permian, , and mid- Kelley (1977) reports that the base of Tertiary rocks. The bench is down- the Santa Fe in this 4223-ft (1287-m)

32 NMBMMR OFR 454A

test hole is 2835 ft (864 m) below the would be required to confirm this floodplain of the Rio Grande valley. interpretation. 1.0 2.2 34.8 Exit I-25 to Camino del Llano (exit 28.4 Rounded hill on left is probably a 191). 0.1 remnant of the Los Duranes Fm. The 34.9 Turn right at stop sign onto Camino del low, arcuate area to the west is probably Llano and ascend hill. 1.1 a meander loop of the ancestral Rio 36.0 Turn around at top of Llano de Grande that was inset into the Los Albuquerque and descend to parking Duranes Fm during late Pleistocene area. 0.1 time. 0.7 36.1 Pull off road. 29.1 Milepost 198. Cliff exposures of Arroyo Stop 1. Belen 7.5’ quadrangle, GPS: Ojito Fm to west. The discontinuous NAD 83, UTM Zone 013 S, N: white soil at the top of the slope is a 3,835,765 m; E: 334, 235 m. strongly developed calcic soil of the Ancestral Rio San Jose facies of the Arroyo Llano de Albuquerque. This soil Ojito Fm. Walk about 200 m down abandoned, exhibits Stage III+ to local Stage IV gullied, dirt road on south side of Camino del carbonate morphology in typically Llano to flat pad cut into upper Santa Fe Group sandy parent material. The north Belen deposits (Fig. 3-1). See mini-paper by Lucas and interchange is ahead at exit 195. 2.0 Morgan (this volume) for a discussion of the 31.1 Railroad overpass. 2.0 stratigraphy and biostratigraphy of this stop. 33.1 Milepost 194. Spur of Arroyo Ojito Fm strata extending east from escarpment on right. 0.7 33.8 Milepost 192. Water tank and Belen sanitary landfill on right. Titus (1963) described a 200-ft (60-m) section of upper Santa Fe beds that crop out in the escarpment badlands area at 3:00. The section is mainly sand and gravelly sand (including cemented sandstone and conglomeratic sandstone lenses) with Figure 3-1. Photograph looking SE of Arroyo several prominent zones of interbedded Ojito Fm outcrops south of Camino del Llano, clay, silt, and fine sand interpreted to be west of Belen, NM. Dave Love for scale in lower part of the Arroyo Ojito Fm. Units are left corner. in upward-fining (channel sand and gravel to overbank silt and clay) Exposures along the bluffs of the western sequences. No angular margin of the Rio Grande valley, near Belen, are noted in the section. Preliminary New Mexico, contain cross-stratified sand and studies of gravel character and pebbly sand correlated to the Arroyo Ojito Fm. sedimentary structures indicate that At this stop, these deposits contain abundant these units may have been deposited on sandstone and chert with lesser amounts of the distal part of a broad piedmont- limestone, granite, and quartzite, with sparse slope/alluvial plain sloping gently scattered, disarticulated Pycnodonte and/or eastward toward the aggrading fluvial Exogyra valves and rounded obsidian pebbles plain of the ancestral river. The log of a derived from the 2.8-3.3 Ma East Grants Ridge Belen municipal water-supply well vent, near Mount Taylor on the eastern Colorado drilled near this base of the described Plateau, in the Rio San Jose watershed (Love and section indicates that, for at least 500 ft Young, 1983; Young, 1982). The limestone and (150 m), the gross lithologic character bivalves are from Cretaceous strata, probably of the basin fill is similar to that of the from the Dakota Fm-Mancos Shale (Greenhorn bluff outcrop (Titus, 1963) and is likely Limestone) interval, exposed in the Rio San Jose correlative to the Arroyo Ojito Fm; drainage basin in the adjacent Colorado Plateau. however, lenses of ancestral Rio Grande The deposits exposed at this stop generally have strata may also be present in the sub- S-SE paleoflow directions, as measured from surface. A study of drillhole cuttings gravel imbrications. These deposits are

33 NMBMMR OFR 454A associated with the ancestral Rio San Jose, a signal the entrenchment of the Rio Puerco valley major tributary to the Rio Puerco. Based on in the Albuquerque Basin. preliminary comparisons of gravel composition of upper Santa Fe Group deposits in the Albuquerque Basin, we provisionally differentiate a western-margin, axial-fluvial, and an eastern-margin piedmont lithofacies that can be used to delineate the distribution of sediment in the Albuquerque Basin during Pliocene time (Fig. 3-2). The Rio Grande forms a rather narrow axial-fluvial systems tract that interfingers with the broader, more extensive western-margin fluvial facies of the Arroyo Ojito Fm. Ancestral Rio Grande deposits interfinger with piedmont deposits (mostly stream-flow dominated conglomerate and sandstone) that form narrow bands on the footwalls of basin-margin uplifts of the Sandia, Manzano, Los Pinos, and Ladron Mts. The white horizontal band at the top of the section is a petrocalcic soil of the Llano de Albuquerque surface (Machette, 1985), which represents a local constructional top of the Arroyo Ojito Fm. The age of the Llano de Albuquerque surface was originally estimated at 0.5 Ma using soil-geomorphic and stratigraphic constraints (Machette, 1985). Additional stratigraphic constraints on the age of this surface indicate that the Llano de Albuquerque surface was formed prior to 1.6 Ma and likely Figure 3-2. Schematic map showing the formed much earlier (Connell et al., 2000; approximate areal distribution of major Maldonado et al., 1999), perhaps as early as 2.7 lithofacies in Pliocene sediments of the upper Ma (see discussion on mile 15.5). Deposition of Santa Fe Group (modified from Connell et al., less than 20 m of Arroyo Ojito Fm sediments 1999). The south-flowing ancestral Rio Grande continued after about 3.00 Ma (40Ar/39Ar date on (ARG) is the axial-fluvial facies (moderate gray interbedded Cat Mesa basalt flow, Maldonado et shading). The Arroyo Ojito Fm (stippled pattern) al., 1999; Connell et al., 2000) on the footwall of comprises a series of major, S-SE-flowing the Cat Mesa fault. Between 75-100 m of tributary drainages originating on the Colorado deposits correlated to the Arroyo Ojito Fm Plateau, San Juan Basin, and Sierra Nacimiento, overlie cinders of the 2.7 Ma Isleta volcano. and include the ancestral Rio Puerco (ARP), Fluvially recycled pumice pebbles correlated to ancestral Rio Guadalupe/Rio Jemez (ARGJ), the early Pleistocene Bandelier Tuff and Cerro ancestral Rio San Jose (ARJ), and ancestral Rio Toledo Rhyolite overlie these western-margin Salado (ARS). These fluvial deposits merge into derived deposits. Other geomorphic constraints a single axial-fluvial system at the southern on the age of the Llano de Albuquerque are from margin of the basin. The conlgomeratic pattern the Rio San Jose drainages, which contains a delineates locally derived deposits from rift- suite of well dated Plio-Pleistocene basaltic margin uplifts. The Cochiti Fm is a piedmont flows near Grants, New Mexico. Entrenchment deposit developed along the SE flank of the of the Rio San Jose and Rio Puerco, on the Jemez Mts (see Smith and Lavine, 1996). Colorado Plateau, was underway since 4 Ma (Love, 1989; Hallett, 1994; Baldridge et al., As you drive east along Camino del Llano 1987; Maldonado et al., 1999), even as the basin towards I-25, note the embayment in the was still filling. Significant entrenchment of the Manzano Mts., along the eastern margin of the Rio San Jose was underway by 2-2.4 Ma (Fig. 3- Albuquerque basin, is less than 25-30 km to the 3). This later period of entrenchment might east. Trigo Canyon is at the southern edge of this

34 NMBMMR OFR 454A embayment, which rests on the footwall of the Mexico Institute of Mining and Technology, Hubbell Springs fault zone. 0.8 funded by grants to Drs. Phillips, Wilson, 36.9 Turn right onto southbound I-25. About Gutjahr and Love, mapped nearly continuously 7 mi. east of this point on the Llano de exposed units about 40 m thick along a belt more Manzano is the Grober-Fuqua #1 oil than 1.2 km long. The goal of the study was to test, drilled between 1937 and 1946. develop geostatistical methods to describe and This 6300-ft (1920-m) hole penetrated predict permeabilities and hydrological 4550 ft (1387m) of Santa Fe Group. heterogeneity in adjacent units based on limited The Santa Fe overlies an unknown drill-hole data. Davis et al. (1997) developed a thickness of beds tentatively correlated portable air mini-permeameter that could be with the Baca Fm (Foster, 1978). applied to the uncemented sandy bluffs to According to other interpretations of measure permeability in situ on the outcrop. well data (Reiche, 1949, p. 1204; Each measurement was located by theodolite Lozinsky, 1987), the section below survey. The overall permeability structure trends 4550 ft comprised 1750 ft (535 m) of to the southeast, along channels mapped in upper Cretaceous and probably Triassic outcrop (Fig. 3-4; Davis et al., 1993; Davis et al., rocks. 0.9 1997). These correlations are remarkably similar 37.8 Milepost 191. 4.7 to the regional paleocurrent directions, as 42.5 Crossing irrigation canal with drop measured from channel geometry, gravel, structures to right. The upper third of imbrication, and cross-stratification, which cliff exposures to your right contain suggests that paleocurrent directional data can be obsidian derived from East Grants used to infer paleogroundwater flow. Mapping of Ridge (Young, 1982). 0.8 calcium-carbonate concretion orientations by 43.7 Milepost 185. Mozley, Davis, and their students show similar In the late 1980s and early 1990s a group of trends (Mozley and Davis, 1996). geology and hydrology students from New

Figure 3-3. Longitudinal profile of the Rio San Jose from the distal end of McCartys flow to the confluence with the Rio Puerco and western edge of the Llano de Albuquerque surface (modified from Love, 1989 with date of Cat Mesa flow from Maldonado et al., 1999). Stratigraphic data indicate that the Llano de Albuquerque is younger than 3.0-2.7 Ma and older than 1.2 Ma. Major incision of the Rio San Jose after about 2.4 Ma suggests that the Llano de Albuquerque surface may have formed somewhat later, perhaps by 2.4-2.0 Ma.

35 NMBMMR OFR 454A

channels) and with episodes of eolian sheet sands and soils. It is debatable whether the large and small channels are part of autocyclic processes on a large fluvial fan or whether they are related to large, episodic climatic shifts during the Pliocene. 0.9 44.6 Socorro County line. To west is a stratigraphic section measured by Lozinsky (1988). 1.0 45.6 Milepost 183. Sabinal Vinyards to your left. Los Pinos Mts. and Black Butte (Turututu) between 10:00-11:00. 1.3 46.9 Rift-bounding Los Pinos Mts. at 10:00. The basin margin trends towards the Joyita Hills, where the Albuquerque basin narrows to less than 10 km in width between the villages of La Joya and San Acacia, known as the Socorro constriction (Kelley, 1977). The low- Figure 3-4. Azimuthal horizontal variograms lying dark-colored hill is Black Butte, constructed by combining horizontal variograms or Turututu, a small horst, which is estimates of N0E, N30E, N90E, N30W, and capped by a basaltic andesite K/Ar N60W. (a) Log-permeability data set; (b) CH-II dated at about 24 Ma (Bachman and element indicator data set. (c) OF element Mehnert, 1978; correlative to the La indicator data set. (d) P element indicator data s Jara Peak basaltic andesite). It overlies set. Contours are in units of dimensionless log- Oligocene La Jencia ashflow tuff permeability square. Contour ranges and (Osburn, 1983; Osburn and Chapin, intervals (range, interval) are (a) (0-10, 1), (b) (b- 1983). 1.7 d) (0-2.5, 0.025). Element indicators shown in 48.6 Milepost 180. Dairy feedlot in Figure 3-5. From Davis et al. (1993). foreground and Los Pinos Mts. in background at 9:00. Northwest sloping Individual facies within the 40-m section cuestas are Pennsylvanian and Permian were lumped into six architectural elements and strata in the northern Sierra de las traced laterally (Fig. 3-5). Two elements were Cañas. Between 12:00-1:00 is the traceable over broad areas—the thick, coarse- Lemitar-Socorro Range, which marks pebble conglomerates that formed the base and the western boundary of the present top of the studied units (CH-I), and eolian sand Socorro basin. The Sabinal fault cuts and soils. Medium-sized channels scoured, back- the Llano de Albuquerque surface to the filled with sand, and overtopped the former west and descends toward the windmill landscape within the larger package of sand-to- in the foreground. This fault has clay units (CH-II). repeatedly moved in Pleistocene time Besides these six elements, a raised channel (Machette et al, 1998; Love 2000). The was found buried within the basin fill (Love et Central New Mexico Livingstone #1 al., 1999). This channel is similar to some found was drilled in 1939 on the Llano de in the Mimbres valley (Love and Seager, 1996). Albuquerque, about 1.7 mi. (2.8 km). to The overall architecture of coarse- and fine- the west (elevation 5074 ft, 1547 mi.), grained units and the raised channel suggest that where it penetrated about 2100 ft (640 this area was built up as part of a larger fluvial m) of Santa Fe Group strata and fan-eolian plain (Mack et al., 1997). The gravels bottomed in possible Cretaceous strata reflect episodes of high discharge connected to at 2978 ft (908 m). 4.8 gravelly headwaters alternating with episodes of lower (perhaps local) discharge (arroyo-like

36 NMBMMR OFR 454A

Figure 3-5. Architectural elements of Arroyo Ojito Fm near Milepost 185. Architectural elements include coarse gravelly sand channels (CH-I), medium- to fine-grained sandy channels (CH-II), overbank silt and clay (OF), and soils (sand, Ps; clay, Pc; and mixed gravel and sand Pgs). From Love et al. (1999).

53.4 Leave I-25 at Bernardo/US-60 exit component may be derived from (exit 175). 0.1 Oligocene rocks of the Mogollon-Datil 53.5 Turn left on old paved road (formerly volcanic field (La Jara Peak basaltic US-85) and pass RV park/campground. andesite and Datil Group), exposed You are in the valley of the Rio Puerco. along the western rift margin. To Route follows geophysical line of southeast is degraded west-facing scarp Consortium for Continental Reflection of the Cliff fault (Machette, 1978a). 1.1 Profiling (COCORP; de Voogd et al., 58.1 Ascend hill of east-facing fault. 1.2 1986). Line was interpreted to show 59.3 Low hills ahead are on the hanging wall deep, shallow-angle, listric faults with of the Loma Pelada fault and consist of steeper normal faults near the surface. cemented piedmont facies of the Sierra 0.9 Ladrones Fm, which are derived from 54.4 Bridge over Rio Puerco. 0.7 the Ladron Mts. McMahon et al. (1998) 55.1 Go straight to gate to Sevilleta National described soil spatial variability in the Wildlife Refuge (NWR) and Long Term slopes of the piedmont for the 1998 Ecological Research (LTER) Area. Dirt Friends of the Pleistocene trip to the road to right leads to Riley and Socorro area. 0.6 Magdalena, New Mexico, via the west 59.9 Cross under powerlines. Between flank of the Ladron Mts. You must 11:00-12:00 are westernmost exposures obtain permission prior to entering of Arroyo Ojito Fm deposits. 1.2 the refuge. Turn right onto dirt road 61.1 Degraded scarp of Loma Blanca fault. immediately after gate and drive west 0.3 towards the Ladron Mts. 0.8 61.4 Descend into Arroyo Tio Lino. Pale 55.9 Ascend degraded fault scarp. 0.3 outcrops to east (left) are cross-stratified 56.2 Turn left towards powerline poles on fluvial deposits of the Sierra Ladrones hill. Ascend mostly covered slopes. 0.8 Fm (Machette, 1978b). 0.4 57.0 Low hill to left contains cemented 61.8 Cross arroyo. 0.4 sandstone and pebbly sandstone that are 62.2 Pull off side of road and walk to likely correlative to the Arroyo Ojito outcrop on east side of arroyo. STOP Fm (Rio Puerco and Rio San Jose 2. San Acacia 7.5’ quadrangle, GPS: fluvial facies). The exposures here also NAD 83, UTM Zone 013 S, N: have gravel beds with abundant 3,803,710 m; E: 380,350 m. volcanic clasts. The volcanic

37 NMBMMR OFR 454A

We are on the San Acacia quadrangle, near in the Socorro and Albuquerque basins (Hawley, the southwestern margin of the Belen sub-basin. 1978; Lucas et al., 1993; Smith and Kuhle, The rift-border Ladron Mts. are to the west. 1998). Conceptually, the Sierra Ladrones Fm Reconnaissance and stratigraphic studies indicate includes the through-going Rio Grande and its the presence of two moderately to well sorted, major tributaries as well as local piedmont. trough cross-stratified fluvial deposits that Machette (1978b) did not define the fluvial interfinger with transverse piedmont deposits at facies as Rio Grande, per se; however, the use of the western and eastern margins of the basin. the symbol “QTsa” suggests that he considered it Treadwell-Steitz (1998) recognized, but did an axial-stream or river (i.e., “a”= axial). not map, fluvial sediments associated with the Researchers from the New Mexico Bureau ancestral Rio Grande east of the Rio Grande (in of Mines and Mineral Resources and New Salas Arroyo and Palo Duro Wash) and east of Mexico Museum of Natural History and Science Machette’s (1978b) mapped extent of eastern recently began a stratigraphic study of the Sierra margin piedmont lithofacies. Geologic mapping Ladrones Fm in the southern Belen sub-basin in by Debrine et al. (1966) indicated the presence of order to document the lithologic character of this a major axial-fluvial system along the eastern widely mapped unit. margin of the Socorro basin. Recent Recent studies in the northern part of the reconnaissance, stratigraphic studies, and Albuquerque Basin demonstrate that the most geologic mapping (Fig. 3-6; Connell et al., 2001; areally extensive fluvial sediments in the basin Cather, 1996; Chamberlin, 1999; Chamberlin et are related to major western-margin tributaries to al. 2001) indicate that the southern Belen sub- the Rio Grande, including the Rio Puerco and basin and northern Socorro basin contain the Rio San Jose. Connell et al. (1999) proposed the paleoconfluence of streams of the Arroyo Ojito Arroyo Ojito Fm for these western-margin river and Sierra Ladrones Fm. deposits, which were divided into mappable The San Acacia quadrangle is the type members or lithofacies, thus excluding these locality for the Sierra Ladrones Fm, which distinct western fluvial deposits as members of a comprises fluvial deposits of a through-going Sierra Ladrones Fm (Connell et al., 1999). river system that interfingers with piedmont The base of the Sierra Ladrones Fm is not deposits derived from local basin-margin uplifts. exposed in Arroyo Tio Lino, but is in fault The Sierra Ladrones Fm (upper Santa Fe Group) contact with the Popotosa Fm (lower Santa Fe was defined by Machette (1978b) without type Group). Elsewhere, mostly in the Socorro and La or reference sections. Instead he designated the Jencia basins (Cather et al., 1994), piedmont San Acacia quadrangle as a type area comprised deposits of the Sierra Ladrones Fm rest upon the of three major facies; a western-margin piedmont Popotosa Fm with angular unconformity. The facies derived from the Ladron Mts; an axial- top of this section is crosscut by Quaternary fluvial facies, generally considered to represent alluvium. the ancestral Rio Grande, derived from the north; At Arroyo Tio Lino, over 350 m of Sierra and an eastern-margin piedmont facies, derived Ladrones Fm strata are exposed between the from the Joyita Hills and eastern rift-border Loma Peleda and Loma Blanca faults (Machette, uplifts. Preliminary results of gravel petrography 1978b). The base of the Arroyo Tio Lino section (Fig. 3-7) suggest that the major lithofacies is a weakly to moderately cemented, tilted, light- assemblages are distinguishable near the gray planar to trough cross-stratified sandstone southern end of the Albuquerque Basin (Fig. 3- (Fig. 3-8, A). Gravel is sparse and composed 6). The gravel clasts are similar in composition mostly of white granite derived from the nearby to gravel data discussed on the Day 1 road log Ladron Mts. Sparse paleocurrent data indicate (Fig. 1-9). The Arroyo Ojito Fm is slightly more deposition by a S-SE flowing river. These volcanic rich near the southern part of the basin. deposits interfinger to the west and upsection This is likely due to the presence of Oligocene (Fig. 3-8, B) with better cemented, piedmont volcanic rocks of the Mogollon-Datil groups sandstone and conglomerate derived from the exposed along the margins of the Socorro and Ladron Mts. Elsewhere, fluvial deposits are southern Albuquerque basins. faulted against older rocks. The top of the section Although the Sierra Ladrones Fm was not contains piedmont deposits with medium bedded defined in accordance to the North American fluvial sandstone interbeds (Fig. 3-8, C). These Code of Stratigraphic Nomenclature (NACSN, fluvial deposits are typically light-gray to very 1983), it was adopted by the U.S. Geological pale-brown, moderately to well sorted, weakly to Survey (Machette, 1978b) and subsequently used

38 NMBMMR OFR 454A

Figure 3-6. Generalized geologic map of the southern Albuquerque and northern Socorro basins in Socorro County. Geologic map was modified from Osburn (1983) using unpublished reconnaissance mapping, including Cather (1996), Chamberlin (1999), and Chamberlin et al. (2001). Queried areas indicate localities in the basin-fill that are currently being studied. Stop locations are noted on the map. Localities mentioned in text include Arroyo de la Parida-North (VPN), Loma Blanca (LB), San Acacia (SAB), Salas Arroyo (SA), La Joya (LJ), Tio Lino (TL), and Picho Hill (PH). Other localities, not mentioned in text, include the Powerline (PL) and north Powerline (NPL) sites. well cemented sandstone with trough cross reference section is more diverse than at Arroyo stratification; mudstone is commonly preserved Tio Lino. Machette (1978b) also considered as rip-up clasts. Also at this site, the beds are exposures at Loma Blanca to be most chaotically bedded, probably due to liquefaction representative of his axial-fluvial facies (unit during paleo-earthquakes. Machette (1978b) QTsa of Machette, 1978b). Measurements on delineated this facies south to Loma Barbon, imbricated gravel and cross stratification indicate where we described a section of similar cross- deposition by a S-SE flowing river. A fluvially bedded sandstone with sparse rounded recycled pumice pebble at Loma Blanca was heterolithic gravel that includes rounded analyzed by N. Dunbar and W.C. McIntosh (NM quartzite. Bureau of Mines and Mineral Resources) and is The Loma Blanca section is part of this geochemically and age-equivalent to the Peralta western outcrop belt that extends north into the Tio Lino section. Gravel at the Loma Blanca

39 NMBMMR OFR 454A

Figure 3-7. Preliminary results of gravel petrography from selected sites in the Belen sub- basin and northern Socorro basin (see Fig. 3-6 for localities). Localities include, La Joya unit 4 (1), Loma Blanca unit 14 (2), La Joya unit 23 (3), Picho Hill (4), La Joya unit 1 (5), Parida North unit 1 (6), San Acacia fluvial (7), La Joya unit 16 (9), Salas Arroyo unit 3 (11), Salas Arroyo unit 4 (12). Black numbers indicate deposits correlated to the ancestral Rio Grande (Sierra Ladrones Fm). Gray numbers indicate deposits provisionally assigned to the southern Figure 3-8. Stratigraphic column of the Tio Lino Arroyo Ojito Fm. Abbreviations include quartz, section illustrating fluvial and piedmont facies of quartzite, and chert (Q), sedimentary (S), the Sierra Ladrones Fm. Thickness is in meters. volcanics (V), and plutonic-metamorphic (PM) gravels. Marker point 3 is an inset fluvial deposit Tuff, which is exposed along the eastern margin of the Rio Salado (Qag of Machette, 1978b), of the Santo Domingo sub-basin and which is similar in composition to marker point 9 southeastern Jemez Mts. The presence of this of the La Joya section. pumice pebble indicates a post-late-Miocene

40 NMBMMR OFR 454A south-flowing fluvial drainage that is likely The Popotosa Fm consists of more than correlative to the ancestral Rio Grande (Connell 2600 m of debris-flow breccia, conglomerate, et al., 2001). Geologic reconnaissance and sandstone, and mudstone that extend in several additional stratigraphic studies are planned to rift-related basins from south of the Socorro document the distribution of lithofacies in the accommodation zone to the Belen sub-basin of southern Belen sub-basin. Fluvial deposits the Albuquerque Basin (Fig. 3-9). It was defined exposed along the western part of the basin are by Denny (1940) who thought it preceded Santa similar in character to deposits recognized east of Fe group deposition, but later workers the Rio Grande at Salas Arroyo (Connell et al., recognized that it is related to early rifting, as 2001). basins and uplifts developed and facies extended Both the Tio Lino and Loma Blanca sections from proximal debris flows to sandy alluvial are exposed in structurally higher fault blocks aprons to central basin mudstone playas along the western margin of the basin are (Bruning, 1973; Cather et al., 1994). During possibly correlative to an older ancestral Rio Popotosa Fm deposition, rift-related basins Grande; however, definitive correlation of the remained closed (internally drained). Basal Tio Lino section to ancestral Rio Grande Popotosa breccias rest on the 27.37±0.07 Ma deposits in the Socorro basin has not yet been South Canyon ash-flow tuff and the 26.3±1.1 Ma established. Alternatively, the Tio Lino section (Bachman and Mehnert, 1978) andesite at may represent deposition by a major western- Cerritos de las Minas (Machette, 1978b). margin tributary to the Rio Grande. Overlying conglomerates contain the 16.2±1.5 Continue driving west on dirt road. 0.4 Ma Silver Creek andesite. Numerous thin silicic 62.6 Increase in cementation of outcrops. In tuffs are preserved in the playa facies. The lithofacies assemblage B of Tio Lino youngest tuff within playa facies near Socorro measured section (Fig. 3-8). 0.1 overlies the 7.85±0.03 Ma rhyolite dome at 62.7 Yellowish-brown concretionary sand- Grefco Mine (Newell, 1997; R.M. Chamberlin, stone beds. Cross transition between 2001, oral commun.). Playa deposits are buried fluvial and piedmont beds between here by the 6.88±0.02 Ma trachyandesite of Sedillo and the mileage 63.1. 0.3 Hill southwest of Socorro. 63.1 Crest of hill on lithofacies assemblage Conceptually, Popotosa Fm deposition C (Fig. 3-8). Bear Mts. on skyline ended as rift basins became integrated from north between 11:00-1:00. The Bear Mts. to south. The earliest evidence for an ancestral contain volcanic deposits of the axial stream in the formerly closed Popotosa Mogollon-Datil volcanic field. Descend basin in the Socorro area is some southward- into Cañada Popotosa and type area of directed cross-bedded fluvial sandstone the Popotosa Fm (lower Santa Fe underlying the 3.73±0.1 Ma basalt of Socorro Group), which was originally defined Canyon. (R.M. Chamberlin and W.C. McIntosh, by Denny (1940) for a reddish-brown written commun., 2000). The ancestral Rio playa-lake mudstone and interfinging Grande fluvial system reached southern New basin-margin piedmont deposits that he Mexico as early as 4.5-5 Ma (Mack et al., 1998). thought pre-dated the Santa Fe Group. The basins containing Popotosa Fm have 0.1 been reconfigured several times during Miocene 63.2 Cross splay of Loma Peleda fault. Note time, particularly with the uplift and extension of reddish-brown playa-lake facies of the the Chupadera-Socorro-Lemitar-Ladron “horst” Popotosa Fm to your right. To your left block in the center of a former more extensive is tilted, cemented piedmont basin. It is possible that the early and late conglomerate of the Sierra Ladrones Miocene playas occupied different basins or Fm. different parts of an evolving basin. Popotosa Fm Pull off road for optional Stop 2b. is primarily exposed in the faulted margins of Continue along dirt road into valley. uplifts and few wells have penetrated the 0.5 formation in basinal positions. 63.7 Pull off road. Turn around and retrace route to I-25. Stop 3. Popotosa Fm overview. San 10.2 Acacia 7.5’ quadrangle, GPS: NAD 83, UTM Zone 013 S, N: 3,803,535 m; E: 317,055 m.

41 NMBMMR OFR 454A

interfingers with reddish-brown piedmont deposits derived from the Joyita Hills and Los Pinos Mts. The fluvial sandstone is correlated to ancestral Rio Grande deposits of the Sierra Ladrones Fm and lies east of the mapped limit of piedmont deposits (unit Tsp of Machette, 1978b) derived from the eastern margin, according to Machette (1978b). 2.9 78.9 Leave I-25 at exit 169 to Sevilleta National Wildlife Refuge. 0.2 79.1 Turn right at stop sign. 0.1 79.2 Gate at entrance to refuge. 0.1 79.3 Turn right to University of New Mexico Field Station. 0.4 79.7 Lunch at UNM Field Station. Retrace route to I-25. 0.6 79.8 Ascend I-25 southbound onramp (MP 171). 1.3 81.1 Pull off highway. STOP 4. La Joya State Wildlife refuge to left. Sevilleta NWR to right. 0.6 The La Joya section represents deposition by streams of the ancestral Rio Puerco/San Jose/Salado fluvial system, not streams from the eastern basin-margin piedmont, as previously interpreted (cf. Machette, 1978b). Figure 3-9. Simplified stratigraphic column for A measured section, about 3 km southwest Cenozoic rocks in the southern Belen sub-basin, of La Joya, NM (Fig. 3-10), was described near and Socorro and La Jencia basins. From Cather here. Deposits are provisionally correlated to the et al. (1994). Arroyo Ojito Fm. Blancan (Pliocene) vertebrates ( simplicidens, and E. scotti(?)) were 73.9 Turn right onto southbound onramp of found in light-brown sandstone, conglomerate, I-25. Magdalena Mts. between 12:00- and bedded mudstone downsection and west of 1:00. Polvadera and Strawberry Peaks this stop. The upper part of the La Joya section is between 11:00-12:00. Socorro Range at interpreted to have been deposited by an E-NE 11:00. 1.0 flowing ancestral Rio Salado. Much of the 74.9 Cross Rio Puerco. The Village of La section, however, was deposited by S-SE Joya is on the east side of the river at flowing streams (Fig. 3-11). 10:00. Bluffs above the town are capped The Salas Arroyo section, just east of the with thin gravels of Arroyo de los Rio Grande, contains trough cross-bedded, Alamos and Salas Arroyo (lower Palo locally tephra-rich, fluvial sand that interfinger to Duro Wash). These surface gravels rest the east with piedmont deposits derived from on sandy fluvial beds here interpreted as adjacent basin-bounding uplifts. an older river-channel deposit inset Exposures near I-25 were originally against fluvial deposits of the ancestral correlated by Machette (1978b) to the piedmont Rio Grande (upper Santa Fe Group). deposits derived from the eastern margin of the Treadwell-Steitz (1998) described the rift; however, paleocurrent data, regional Palo Duro Wash soil chronosequence. lithofacies patterns, and paleogeography (Figs. 3- 1.1 7, 3-10, and 3-11) suggest that these deposits 76.0 White beacon at 10:00 is on terrace of were not derived from the eastern margin, but Salas Arroyo on the eastern part of the from the western margin instead. Preliminary Sevilleta NWR. Deposits in Salas results of gravel composition studies suggest a Arroyo contain light-gray, trough-cross closer correlation to the Arroyo Ojito Fm than bedded, fluvial sandstone that eastern-margin piedmont or ancestral Rio Grande

42 NMBMMR OFR 454A deposits. Piedmont deposits to the E and SE of Aperture Radar (InSAR) from satellites this stop contain abundant granite and reddish- yielding a value of 3-4 mm/yr brown sandstone, which are rare or absent in the (http://igpp.ucsd.edu/~fialko/res_socorr La Joya section. o.html[2001]). 0.1

Figure 3-10. Stratigraphic column of La Joya site, Stop 4. The base contains a light-gray sand that is possibly correlative to the ancestral Rio Grande facies (Sierra Ladrones Fm). This is overlain by deposits of the Arroyo Ojito Fm, which are provisionally subdivided into a Rio San Jose (Tosj) and overlying Rio Salado (Tors) Figure 3-11. Paleocurrent rose (in 10° intervals) facies. The section is unconformably overlain by for Arroyo Ojito Fm (upper Santa Fe Group) Quaternary terrace gravel of the Rio Salado (unit near Stop 4, including correlation coefficient (r). Qag of Machette, 1978b). Thickness in meters. The NE-trending cluster is from the upper part of the section (Fig. 3-10), which contains abundant 81.7 Milepost 168 The well-preserved fan- volcanic gravel correlated to the ancestral Rio terrace surface (Qag of Machette, Salado. 1978b,c) is graded to a level about 130 ft (40 m) above the present floodplain. 82.6 Rest area on right. 1.2 Denny (1940) also describes cut-and-fill 83.8 Bridge over Rio Salado. At 9:00 note terraces in the La Joya area. 0.8 tilted red-beds of the Joyita Hills, which 82.5 Descend into valley of the Rio Salado, define the eastern margin of the basin. near the southern margin of the The Joyita Hills are a complex fault Albuquerque Basin. Sand dunes on both block of Proterozoic, upper Paleozoic, sides of I-25. From here to San Acacia, and lower to middle Tertiary rocks NM (MP 163), is the area of maximum (Foster and Kottlowski, 1963; Beck, uplift above the Socorro body, a 1991). The Tertiary sequence includes a 3,400 km2 pancake-shaped sill thin conglomerate of the Baca Fm recognized at a depth of 18.75 km (Eocene), which rests on an erosion (Sanford and Long, 1965; Reinhart and surface cut nearly through the Triassic Sanford, 1981; Ake, and Sanford 1988; beds, and a thick sequence of Oligocene Hartse, 1991; Hartse, et al., 1992; andesitic to rhyolitic volcanic rocks. Balch et al., 1997). The rate of Ash-flow tuffs derived from areas west magmatic inflation at the center of the of the rift are found east of the Joyita uplift near San Acacia has been Hills. 0.8 estimated using repeated conventional 84.6 Milepost 165. Low dark mesas on both geodetic surveys yielding an uplift sides of river at 10:00 consist of the value of 1.8 mm/yr (Reilinger and trachyandesite at San Acacia, which Oliver,1976; Larsen et al, 1986) and overlies easterly-derived distal using Interferometric Synthetic piedmont deposits of the Sierra

43 NMBMMR OFR 454A

Ladrones Fm. Recently the (rhyolite ash-flow tuffs and andesite trachyandesite has been 40Ar/39Ar-dated flows) that overlie the Pennsylvanian at 4.87±0.04 Ma (W.C. McIntosh, and and in places the Proterozoic. The R.M. Chamberlin, unpubl. data). The southern and northern ends of the range western face of the north mesa exposes are overlapped by Santa Fe beds, down-faulted light-gray fluvial sand including fanglomerate and playa with scattered gravel correlated to the mudstone facies of the Popotosa Fm ancestral Rio Grande facies of the (Miocene) and piedmont gravel and Sierra Ladrones Fm. These fluvial fluvial sand facies of the Sierra deposits are faulted against the Ladrones Fm. 0.6 piedmont deposits beneath the lava. To 93.1 Leave I-25 at Lemitar exit (156). 0.2 the south, the cliffs along the eastern 93.3 Left at stop sign, towards Lemitar to margin of the valley are piedmont east. 0.5 deposits with interbedded fluvial 93.8 Turn right onto Severo Vigil Road to deposits of the ancestral Rio Grande. A Escondida Lake Park. Travel along toe water well drilled on the floodplain east of valley border fans. 1.8 of I-25 penetrated 27 m of late 95.6 Valley of Arroyo de la Parida east of Pleistocene-Holocene fill of the Rio the river at 9:00. Reddish-brown fan Grande valley. 2.0 gravels to fanglomerate (derived in part 86.6 San Acacia overpass. Loma Blanca at from Permian red beds in the Loma de 3:00 is rounded hill formed on sandy las Cañas) interfinger westward with fluvial beds of the Sierra Ladrones Fm. finer grained distal-piedmont to basin- The Rio Grande at 9:00 is cut through floor facies that include tongues of gray the trachyandesite into eastern piedmont pebbly sands deposited by the ancestral facies. Slump blocks of trachyandesite river. The sequence consists of the and at least two terrace levels are eastern piedmont and fluvial facies of preserved downstream from this the Sierra Ladrones or Palomas fms; watergap. 1.0 interfingering relationships were first 87.6 Milepost 162. On Rio Grande described by DeBrine et al. (1963). floodplain. Dark-reddish-brown hills Vertebrate collected from fluvial are 3:00 are the Cerritos de las Minas. sands in the south bluff of the arroyo They are formed on 26-m.y.-old basaltic valley are of medial Blancan age (see andesite correlated with the La Jara mini-paper by Morgan and Lucas, this Peak andesite (Machette, 1978b; volume). The sparse fauna was Osburn and Chapin, 1983). Type originally described by Needham Popotosa Fm (Bruning, 1973) is farther (1936). According to Bachman and west. 1.0 Mehnert (1978, p. 288), the basal fluvial 88.6 Crossing San Lorenzo Arroyo. 2.9 sand zone in the Arroyo de la Parida 91.5 Milepost 158. Gravel pits on left are exposures rises “85 m [280 ft] in quarrying inset fluvial deposits of the altitude northward over a distance of ancestral Rio Grande. These exposures about 11 km [7 mi.] along the east side contain teeth and fluvially of the Rio Grande, representing a recycled gravels containing obsidian gradient of about 7.7 m/km [about 40 from the Jemez Mts. (R. H. Weber, oral ft/mi], compared with the existing commun. 2001). 1.0 gradient of about 1.0 m/km [about 5 92.5 Milepost 157. The east slope of the ft/mi].” This upwarped part of the upper Lemitar Mts. at 1:00-3:00 includes Santa Fe sequence extends north almost Proterozoic granite, schist, pegmatite, to San Acacia and coincides with the and diabase dikes. Just below the high area where the preliminary studies of point of the range, Polvadera Mountain, railroad level-line data by Reilinger and Pennsylvanian (Madera) limestone is in Oliver (1976) indicate high (4-6 mm/yr) fault contact with Proterozoic rocks. rates of present uplift (see discussion at Near the south end of the range mileage 82.5). 0.5 Mississippian and Pennsylvanian rocks 96.1 Road cuts exposing piedmont deposits overlie the Proterozoic. The peak is derived from the Socorro Range. 0.7 formed on Oligocene volcanic rocks 96.8 Turn left to Escondida Lake. 0.1

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96.9 Cross railroad tracks, Escondida Lake evolution of the Socorro area. The lithologic to north (left). 0.2 composition of upper Santa Fe Group basin fills 97.1 Bridge over Rio Grande. 0.5 and post-Santa Fe valley fills reflect major 97.6 Ascend hill of Pueblito and turn left structural and topographic elements of the Rio onto dirt road toward Valle de la Parida. Grande rift that had formed by early Pliocene. 1.3 The erosional valley of the Rio Grande, formed 98.9 Ascend Johnson Hill and climb out of since mid-Pleistocene time, was the only major Valle de la Parida. 0.3 geomorphic feature not yet present. Earlier 99.2 Ancestral Arroyo de la Parida deposit deposits of intrarift basins, the bolson-fill facies that is inset into gently east-tilting Santa and volcanics of the upper Oligocene-Miocene Fe Group strata. 1.0 Popotosa Fm, are here deeply buried; they reflect 100.2 Turn left onto high-level terrains largely obliterated by erosion, piedmont/tributary deposit inset against sedimentation, and structural deformation in the basin fill of upper Santa Fe Group. 0.2 past 10 Ma. 100.4 Bear right and park along loop. STOP The geomorphic setting, in terms of 5. Mesa del Yeso 7.5’ quadrangle, hydrologic and biologic conditions, was GPS: NAD 83, UTM Zone 013 S, N: probably not much different from that of the late 3,779,760 m; E: 329,555 m. Quaternary. Calcic paleosols associated with The following discussion is modified buried and relict geomorphic surfaces indicate (comments indicated by brackets, “[ ]”) from that climatic conditions were semiarid to arid. minipaper in New Mexico Geological Society Basin- and valley-fill facies patterns clearly Guidebook 34 (Hawley, 1983, p. 13) on the show that ephemeral, high-gradient (arroyo) Geomorphic Evolution of Socorro area of Rio tributaries dominated piedmont-slope Grande valley: depositional environments, while a perennial, Johnson Hill offers a good vantage point for low gradient fluvial (axial-river) system reviewing the post-Miocene geomorphic occupied the basin floor.

Figure 3-12. Diagramatic cross section across the Socorro basin. “STOP 3” on cross section is near Stop 5 of this guidebook. From Hawley (1983).

The diagrammatic cross section from the Pliocene to early Pleistocene age (more than 1.5 Nogal Canyon area (north of Socorro Peak) to m.y., Tedford, 1981; Lucas and Morgan, this the vicinity of this stop [Fig. 3-12] illustrates the guidebook). This unit is extensively preserved in complex history of late stages of basin filling and bluffs east of the Rio Grande and intertongues the episodic nature of middle to late Pleistocene with thick fan deposits of the eastern piedmont valley cutting. The earliest axial-river deposits facies of Sierra Ladrones Fm. Debrine et al. (3-5 Ma) were apparently emplaced along the (1963) clearly show these facies relationships in western margin of the basin and are now partly the valley-border area between San Acacia and incorporated in the uplifted Socorro Mtn block Arroyo de las Cañas. Between 1.5 and 0.5 Ma [Chamberlin, 1980; 1999]. Fluvial sands exposed ago, the ancestral Rio Grande had again shifted along the lower reach of Arroyo de la Parida westward to a position just west of the present contain a Blancan vertebrate fauna of late valley in the Socorro-Escondida area. Volcanic

45 NMBMMR OFR 454A ash from caldera-forming eruptions in the Jemez to be done before geomorphic surfaces and Mts between 1.1 and 1.4 Ma [now 1.2-1.6 Ma] stratigraphic units can be formally defined. ago is present in axial-river deposits of the Sierra Follow road back down Johnson Hill to Ladrones Fm exposed in the Luis Lopez valley of Arroyo de la Parida. 0.3 quadrangle (Chamberlin, 1999). Tephra and 100.7 White exposures across Rio Grande pumice from these eruptions is also present in valley are the Grefco perlite mine (7.85 Sierra Ladrones fluvial facies about 3 mi. NE of Ma) at the eastern flank of the Socorro San Antonio. Culmination of basin filling and Range. The 3.78 Ma Socorro Canyon the end of Santa Fe Group (Sierra Ladrones Fm) flow south of the mine overlies deposition occurred about 0.5 Ma ago ancestral Rio Grande deposits and is throughout the Albuquerque to El Paso region faulted down-to-the-east by the Socorro (Hawley et al., 1976; [now considered to be Canyon fault (Chamberlin, 1999; earlier; 1.0-0.7 Ma]). The summit area of Ayarbe, 2000). 1.6 Johnson Hill probably approximates the ultimate 102.3 Turn right onto dirt road on north bank level of basin aggradation. The history of late of Parida Arroyo. 0.7 stages of basin filling represented by the Sierra 103.0 Bear right at top of hill onto Quaternary Ladrones Fm is obviously complicated by tributary/piedmont deposits. 0.4 significant structural deformation (Machette, 103.4 Cross arroyo. 0.2 1978b) as well as by shifts in hydrologic 103.6 Cross arroyo. 0.4 regimes. Detailed surface, subsurface, 104.0 Proceed through gate. 0.1 biostratigraphic and tephrochronologic studies of 104.1 Pull off road near arroyo floor. Stop 6. Sierra Ladrones Fm are just getting started in the Look at detailed sedimentary structures Socorro area and much work still needs to be of the ancestral Rio Grande. Upstream done. are cemented faults cutting the fluvial The modern valley is a relatively narrow deposits. Mesa del Yeso 7.5’ erosional feature of a river system that is just quadrangle, GPS: NAD 83, UTM Zone beginning to cut its way into an enormous 013 S, N: 3,779,975 m; E: 327,235 m. volume of older fluvial deposits. Valley Gordon (1910) first described deposits of landforms represent at least 4 major episodes of Arroyo de la Parida as the Palomas gravels (now river entrenchment separated by periods of Fm). The Palomas Fm is one of the oldest partial valley back filling or relatively steady- stratigraphic terms in the Rio Grande rift (see state conditions in terms of local floodplain base Lozinsky and Hawley, 1985a), however, it was levels. Episodes of widespread valley incision not formally defined until Lozinsky and Hawley appear to correlate with major expansions of (1986b) designated a type section near Truth or pluvial lakes and alpine glaciers in the southern Consequences, NM, about 120 km south of Rocky Mountain and Basin and Range Socorro, NM. Although Gordon (1910) mapped provinces. The extensive remnants of graded the Palomas gravels near San Marcial, NM, surfaces flanking the inner Rio Grande valley in about 50 km south of this stop, a photograph of this region represent not only early valley Arroyo de la Parida was shown as an example of degradational stages, but also long periods of the Palomas gravels. The antiquity of the valley-floor aggradation or relative gradational ancestral Rio Grande system was demonstrated stability. The latter intervals probably reflect by Needham (1936) who reported the presence interglacial environments of the type exhibited in of the Pliocene elephant Rynchotherium in the Holocene when tributary (arroyo) drainage fluvial deposits in Arroyo de la Parida (see systems delivered more sediment to valley floors Morgan and Lucas, this volume). Debrine et al. than master streams could remove from the (1963) delineated piedmont and fluvial facies in middle Rio Grande basin. the northern Socorro basin, which were The Socorro area is a classic area in terms of subsequently assigned to the Sierra Ladrones Fm being the site of early studies on desert-valley by Machette (1978d) in his compilation of the evolution by Kirk Bryan and his students. Most Socorro 1º x 2º, and later by Osburn (1983) in of the early geomorphic work was done by the Socorro County geologic map. Hawley Denny (1940). As in the case of studies on the (1978) extended the term Sierra Ladrones Fm to upper Santa Fe Group, structural and the Albuquerque and Socorro basins. Subsequent paleoclimatic complications are not conducive mapping differentiated additional lithofacies in for simplistic models of evolution of valley- the axial-fluvial and piedmont units (Cather, border landforms; much detailed work remains 1996; Chamberlin, 1999, 2001, Chamberlin and

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Eggleston, 1996), although recent work suggests Near the northern margin of the Mesilla that deposits in Arroyo de la Parida, and perhaps basin, just south of Hatch, NM, and about 175 the throughout the Socorro basin, should be km south of Socorro, NM, the Rio Grande assigned to the Palomas Fm (Morgan et al., system forms a large, distributary fluvial 2000). braidplain of the Camp Rice Fm extending The Albuquerque Basin is 30-55 km in southward into closed basins of the - width and represents the southernmost major Chihuahua border region (Lozinsky and Hawley, contributory basin of the Rio Grande system 1991). (Lozinsky and Hawley, 1991), where the Rio We provisionally favor re-assignment of Grande fluvial system received water and deposits in Arroyo de la Parida to the Palomas sediment from large perennial tributaries, such as Fm for the following reasons: 1) Arroyo de la the Rio Puerco, Rio Jemez, and Rio Chama, that Parida was part of the original Palomas Fm originated in the southern and concept of Gordon (1910); 2) the transition from Colorado Plateau. With an area of 19,040 km2 contributory drainage in the Albuquerque Basin the Rio Puerco drainage basin is the largest to trunk-river deposition to the south, as tributary to the Rio Grande in New Mexico and delineated by the distribution of the Arroyo Ojito drains uplands that reach about 3200 m (10,500 Fm, suggests the presence of single axial-fluvial ft) in elevation (Heath, 1983). The Rio Puerco system south of San Acacia, NM; and 3) the currently enters the Rio Grande near the southern structural setting of the Socorro basin (i.e., well terminus of the Albuquerque Basin. The Rio defined half graben) and stratigraphic Puerco system and other large drainages that architecture of its deposits are quite similar to originate along the western margin of the basin those of the Palomas and Engle basins, which are part of the Arroyo Ojito Fm concept of have been assigned to the Palomas Fm; however, Connell et al. (1999). The contributory aspect of further study is underway to test this proposed the Albuquerque Basin is expressed in the assignment. concept of the Arroyo Ojito Fm, which forms the Retrace route back to I-25. End Day 3 road log. largest (volumetrically and areally) component of the upper Santa Fe Group basin-fill system in ROAD LOG REFERENCES the Albuquerque Basin. The boundary between the Socorro and Albuquerque basins lies between Ake, J.P., Sanford, A.R., 1988. New evidence for the Rio Salado and San Lorenzo Arroyo. At this the existence and internal structure of a thin transition, the Arroyo Ojito Fm is difficult to layer of magma at mid-crustal depths near distinguish, and presumably becomes integrated Socorro, New Mexico: Seismological with the Rio Grande. Society of America Bulletin, v. 78, p. 1335- The Socorro, San Marcial, Palomas, and 1359. Engle basins are considerably narrower than the Ayarbe, J. P., 2000, Coupling a fault-scarp Albuquerque Basin and form fairly simple half- diffusion model with cosmogenic 36Cl graben basins. The Socorro basin is about 9-12 rupture chronology of the Socorro Canyon km wide and was formed as the Lemitar and fault, New Mexico [M.S. thesis]: Socorro, Socorro ranges were uplifted during late New Mexico Institute of Mining and Miocene time (Cather et al., 1994). The Rio Technology, Socorro, 71 p. Grande system converges into a single trunk Bachman, G. O., and Mehnert, H.H., 1978, New river, with local distributary and tributary K-Ar dates and the late Pliocene to drainages, in the northern Socorro basin, where Holocene geomorphic history of the central both the ancestral and modern rivers are bound Rio Grande region, New Mexico: within a relatively narrow half-graben basin with Geological Society of America, Bulletin, v. relatively well defined footwall and hangingwall 89, p. 283-392. drainages. In these basins the Rio Grande system Balch, R.S., Hartse, H.E., Sanford, A.R., and is confined to a relatively narrow axial zone in Lin, K.W., 1997, A new map of the the deepest part of these half-graben basins geographic extent of the Socorro mid-crustal (Lozinsky and Hawley, 1991). The presence of magma body: Seismological Society of larger tributary drainages, such as Palomas and America Bulletin, v. 87, p. 174-182. Cuchillo Creeks, influences sedimentation in Baldridge, W.S., Perry, F.V., and Shafiqullah, these well-defined half-graben basins, but M., 1987, Late Cenozoic volcanism of the probably not to the extent as in the Albuquerque southeastern Colorado Plateau: I. Volcanic Basin. geology of the Lucero area, New Mexico:

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Geological Society of America Bulletin, v. Chamberlin, R.M., and Eggleston, T.L., 1996, 99, n. 10, p. 463-470, 1 pl. Geologic map of the Luis Lopez 7.5-minute Beck, W. C., 1993, Structural evolution of the quadrangle, Socorro County, New Mexico: Joyita Hills, Socorro County, New Mexico New Mexico Bureau of Mines and Mineral [Ph.D. dissert.]: Socorro, New Mexico, New Resources, Open-file report 421, 152 p., 2 Mexico Institute of Mining and Technology, pl. 187 p. Chamberlin, R.M., Pazzaglia, F.J., Wegman, Brown, L. D., Chapin, C. E., Sanford, A. R., K.W., and Smith, G.A., 1999, Preliminary Kaufman, S., and Oliver, J., 1980, Deep geologic map of Loma Creston quadrangle, structure of the Rio Grande rift from seismic Sandoval County, New Mexico: New reflection profiling: Journal of Geophysical Mexico Bureau of Mines and Mineral Research, v. 85, p. 4773-4800. Resources, Open-file Digital Map DM 25, Bruning, J. E., 1973, Origin of the Popotosa scale 1:24,000. Formation, north-central Socorro County, Chamberlin, R.M., Cather, S.M., Nyman, M., New Mexico [PhD. thesis]: Socorro, New and McLemore, V., 2001, Preliminary Mexico Institute of Mining and Technology, geologic map of the Lemitar 7.5-min. 142 p. quadrangle, Socorro County, New Mexico, Bryan, K and McCann, F. T., 1937, The Ceja del New Mexico Bureau of Mines and Mineral Rio Puerco, a border feature of the Basin Resources, Open-file Geologic Map OF-GM and Range province in New Mexico: Journal 38, scale 1:24,000. of Geology, v. 45, p. 801-828. Connell, S.D., 1997, Geology of the Alameda Bryan, K., and McCann, F.T., 1938, The Ceja 7.5-minute quadrangle, Bernalillo and del Rio Puerco-a border feature of the Basin Sandoval Counties, New Mexico: New and Range province in New Mexico, part II, Mexico Bureau of Mines and Mineral geomorphology: Journal of Geology, v. 45, Resources, Open-File Digital Map 10, scale p. 1-16. 1:24,000. Cather, S.M., 1996, Geologic maps of upper Connell, S.D., 1998, Geology of the Bernalillo Cenozoic deposits of the Loma de las Cañas 7.5-minute quadrangle, Sandoval County, and Mesa del Yeso 7.5-minute quadrangles, New Mexico: New Mexico Bureau of Mines New Mexico: New Mexico Bureau of Mines and Mineral Resources, Open-File Digital and Mineral Resources, Open-file report Map 16, scale 1:24,000. 417, 32 p., 2 pl. Connell, S.D., and Wells, S.G., 1999, Pliocene Cather, S.M., and Connell, S.D., 1998, Geology and Quaternary stratigraphy, soils, and of the San Felipe Pueblo 7.5-minute tectonic geomorphology of the northern quadrangle, Sandoval County, New Mexico: flank of the Sandia Mountains, New New Mexico Bureau of Mines and Mineral Mexico: implications for the tectonic Resources, Open-File Digital Map 19, scale evolution of the Albuquerque Basin: New 1:24,000. Mexico Geological Society, Guidebook 50, Cather, S.M., Chamberlin, R.M., Chapin, C.E., p. 379-391. and McIntosh, W.C., 1994, Stratigraphic Connell, S.D. Cather, S.M., Karlstrom, K.E., consequences of episodic extension in the Read, A., Ilg, B., Menne, B., Picha, M.G., Lemitar Mountains, central Rio Grande rift: Andronicus, C., Bauer, P.W., and Anderson, Geological Society of America, Special O.J., 1995, Geology of the Placitas 7.5- Paper 291, p. 157-170. minute quadrangle, Sandoval County, New Chamberlin, R.M., 1980, Cenozoic stratigraphy Mexico: New Mexico Bureau of Mines and and structure of the Socorro Peak volcanic Mineral Resources, Open-File Digital Map center, central New Mexico: New Mexico 2, scale 1:12,000. Bureau of Mines and Mineral Resources, Connell, S.D., Allen, B.D., and Hawley, J.W., Open-file report 118, 532 p., 3 pl. 1998a, Subsurface stratigraphy of the Santa Chamberlin, R. M., 1999, Preliminary geologic Fe Group from borehole geophysical logs, map of the Socorro quadrangle, Socorro Albuquerque area, New Mexico: New County, New Mexico: New Mexico Bureau Mexico Geology, v. 20, n. 1, p. 2-7. of Mines and Mineral Resources, Open-file Connell, S.D., Allen, B.D., Hawley, J.W., and Digital Map Series OF-DM-34, 46 p., scale Shroba, R., 1998b, Geology of the 1:24,000. Albuquerque West 7.5-minute quadrangle, Bernalillo County, New Mexico: New

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Mexico Bureau of Mines and Mineral deVoogd, B., Brown, L. D., and Merey, C., Resources, Open-File Digital Geologic Map 1986, Nature of the eastern boundary of the 17, scale 1:24,000. Rio Grande rift from COCORP surveys in Connell, S.D., Koning, D.J., and Cather, S.M., the Albuquerque basin, New Mexico: 1999, Revisions to the stratigraphic Journal of Geophysical Research, v. 91, p. nomenclature of the Santa Fe Group, 6305-6320. northwestern Albuquerque basin, New Formento-Trigilio, M.L., and Pazzalgia, F.J., Mexico: New Mexico Geological Society, 1998, The tectonic geomorphology and Guidebook 50, p. 337-353. long-term landscape evolution of the Connell, S.D., Love, D.W., Maldonado, F., southern Sierra Nacimiento: traditional and Jackson, P.B., McIntosh, W.C., and Eppes, new techniques in assessing long-term M.C., 2000, Is the top of the Santa Group landscape evolution of the southern Rocky diachronous in the Albuquerque Basin? Mountains: Journal of Geology, v. 106, p. [abstract]: U.S. Geological Survey, Open- 433-453. file report 00-488, p. 18-20. Foster, R. W., 1978, Selected data for deep drill Connell, S.D., Love, D.W., Jackson-Paul, P.B., holes along Rio Grande rift in New Mexico: Lucas, S.G., Morgan, G.S., Chamberlin, New Mexico Bureau of Mines and Mineral R.M., McIntosh, W.C., Dunbar, N., 2001, Resources, Circular 163, p. 236-237. Stratigraphy of the Sierra Ladrones Foster, R. W., and Kottlowski, F. E., 1963, Field Formation type area, southern Albuquerque trip 2, Joyita Hills: New Mexico Geological Basin, Socorro County, New Mexico: Society Guidebook 14, p. 42-52. Preliminary Results [abstract]: New Mexico Galusha, T., 1966, The Zia Sand Formation, new Geology, v. 23, n. 2, p. 59. early to medial Miocene beds in New Davis, J. M., Lohmann, R. C., Phillips, F. M., Mexico: American Museum Novitiates, v. Wilson, J. L., and Love, D. W., 1993, 2271, 12 p. Architecture of the Sierra Ladrones Galusha, T. and Blick, J. C., 1971, Stratigraphy Formation, central New Mexico: of the Santa Fe Group, New Mexico: Depositional controls on the permeability Bulletin of the American Museum of correlation structure: Geological Society of Natural History, v. 144, 127 p. America Bulletin, v. 105, p. 998-1007. Gawne, C. E., 1981, Sedimentology and Davis, J.M., Wilson, J.L., and Phillips, F.M., stratigraphy of the Miocene Zia Sand of 1994. A portable air-minipermeameter for New Mexico: Summary: Geological Society in-situ field measurements, Ground Water, of America Bulletin, v. 92, p. 999-1007. v. 32, p. 258-266. Gordon, C.H., 1910, Sierra and central Socorro Davis, J.M., Wilson, J.L., Phillips, F.M., and Counties, in Lindgren, W., Graton, L.C., and Gotkowitz, M.D., 1997, Relationship Gordon, C.H., eds, The ore deposits of New between fluvial bounding surfaces and the Mexico: U.S. Geological Survey, permeability correlation structure, Water Professional Paper 68, p. 213-285. Resources Research, v. 33, n. 8, p. 1843- Grauch, V.J.S., 1999, also this volume, Principal 1854. features of high-resolution aeromagnetic DeBrine, B., Spiegel, Z., and William, D., 1963, data collected near Albuquerque, New Cenozoic sedimentary rocks in Socorro Mexico: New Mexico Geological Society, valley, New Mexico: New Mexico Guidebook 50, p. 115-118. Geological Society, Guidebook 14, p. 123- Grauch, V.J.S., Gillespie, C.L., and Keller, G.R., 131. 1999, also this volume, Discussion of new Denny, C. S., 1940, Tertiary geology of the San gravity maps for the Albuquerque Basin Acacia area, New Mexico: Journal of area: New Mexico Geological Society, Geology, v. 48, p. 73-106. Guidebook 50, p. 119-124. Denny, C. S., 1941, Quaternary geology of the Hallett, R.B., 1994, Volcanic geology, San Acacia area, New Mexico: Journal of , , and Geology, v. 49, p. 225-260. geochemistry of the Rio Puerco Necks, Derrick, N.N., and Connell, S.D., 2001, west-central New Mexico [Ph.D. dissert.]: Petrography of upper Santa Fe Group Socorro, New Mexico Institute of Mining deposits in the northern Albuquerque basin, and Technology, 340 p. New Mexico: Preliminary Results [abstract]: Hartse, H.E., A.R. Sanford, and J.S. Knapp, New Mexico Geology, v. 23, n. 2, p. 58-59. 1992. Incorporating Socorro magma body

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reflections into the earthquake location New Mexico: Mexico Bureau of Mines and process, Seismological Society of America Mineral Resources Open-File Geologic Map Bulletin, v. 82, p. 2511-2532. OF-GM48, scale 1:24,000. Hartse, H.E., 1991. Simultaneous hypocenter and Lambert, P. W., 1968, Quaternary stratigraphy of velocity model estimation using direct and the Albuquerque area, New Mexico [Ph.D. reflected phases from microearthquakes dissert.]: Albuquerque, University of New recorded within the central Rio Grande rift, Mexico, 329 p. New Mexico [Ph.D. dissert.]: Socorro, New Large, E., and Ingersoll, R.V., 1997, Miocene Mexico Institute of Mining and Technology, and Pliocene sandstone petrofacies of the 251 p. northern Albuquerque Basin, New Mexico, Hawley, J.W., ed., 1978, Guidebook to Rio and implications for evolution of the Rio Grande rift in New Mexico and Colorado: Grande rift: Journal of Sedimentary New Mexico Bureau of Mines and Mineral Research, Section A: Sedimentary Petrology Resources, Circular 163, 241 p. and Processes, v. 67, p. 462-468. Hawley, J.W., 1983, Geomorphic evolution of Larsen, S., Reilinger, R., and Brown, L., 1986, Socorro area of Rio Grande valley: New Evidence for ongoing crustal deformation Mexico Geological Society Guidebook 34, related to magmatic activity near Socorro, p. 13. New Mexico: Journal of Geophysical Hawley, J.W., and Galusha, T., 1978, Bernalillo Research, v. 91, p. 6283-6292. to south of San Ysidro: New Mexico Bureau Lipman, P. W., and Mehnert, H. H., 1980, of Mines and Mineral Resources, Circular Potassium-argon ages from the Mount 163, p. 177-183. Taylor volcanic field, New Mexico: U. S. Hawley, J.W., Bachman, G.O., and Manley, K., Geological Survey Professional Paper 1976, Quaternary stratigraphy of Basin and 1124B, p. B1-B8. Range and Great Plains provinces, New Love, D.W., 1989, Geomorphic development of Mexico and Western Texas, in Mahaney, the Rio San Jose valley: New Mexico W.C., ed., Quaternary stratigraphy of North Geological Society, Guidebook 40, p. 11-12. America: Dowden, Hutchinson, and Ross, Love, D. W., 2000, Preliminary geologic map of Stroudsburg, Pennsylvania, p. 235-274. Veguita quadrangle: New Mexico Bureau of Heath, D., 1983, Flood and recharge Mines and Mineral Resources, Open-file relationships of the lower Rio Puerco, New Geologic Map 28, 1:24,000. Mexico: New Mexico Geological Society, Love, D.W., and Young, J.D., 1983, Progress Guidebook 34, p. 329-337. report on the late Cenozoic geologic Hook, S. C., and Cobban, W. A.,1977, evolution of the lower Rio Puerco: New Pycnodonte Newberryi (Stanton)—Common Mexico Geological Society, Guidebook 34, guide fossil in Upper Cretaceous of New p. 277-284. Mexico: New Mexico Bureau of Mines and Love, D.W., and Seager, W.R., 1996, Fluvial Mineral Resources, Annual Report 1976- fans and related basin deposits of the 1977, p. 48-54. Mimbres drainage: New Mexico Geology, v. Karlstrom, K.E., Cather, S.M., Kelley, S.A., 18, n. 4, p. 81-92. Heizler, M.T., Pazzaglia, F.J., and Roy, M., Love, D. W., Whitworth, T. M., Davis, J. M., 1999, Sandia Mountains and the Rio Grande and Seager, W. R., 1999, Free-phase NAPL- rift: ancestry of structures and history of trapping features in intermontane basins: deformation: New Mexico Geological Environmental and Engineering Geoscience, Society, Guidebook 50, p. 155-165. v. V., n. 1, p. 87-102. Kelley, V. C., 1977, Geology of Albuquerque Love, D.W., Dunbar, N., McIntosh, W.C., Basin, New Mexico: New Mexico Bureau of McKee, C., Connell, S.D., Jackson-Paul, Mines and Mineral Resources, Memoir 33, P.B., and Sorrell, J., 2001, Late-Miocene to 60 p. early-Pleistocene geologic history of Isleta Kelley, V. C. and Kudo, A. M., 1978, Volcanoes and Hubbell Spring quadrangles based on and related basalts of Albuquerque basin, ages and geochemical correlation volcanic New Mexico: New Mexico Bureau of Mines rocks [abstract]: New Mexico Geology, v. and Mineral Resources Circular 156, 30 p. 23, n. 2, p. 58. Koning, D., Pederson, J., Pazzaglia, F.J., 1998, Lozinsky, R.P., 1988, Stratigraphy, Geology of the Cerro Conejo (Sky Village sedimentology, and sand petrography of the NE), 7.5 min quadrangle, Sandoval county, Santa Fe Group and pre-Santa Fe Tertiary

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deposits in the Albuquerque Basin, central Machette, M.N., 1978d, Preliminary geologic New Mexico [Ph.D. dissert.]: Socorro, New map of the Socorro 1º x 2º quadrangle: U.S. Mexico Institute of Mining and Technology, Geological Survey, Open-file report 78-607, 298 p. scale 1:250,000. Lozinsky, R. P., 1994, Cenozoic stratigraphy, Machette, M.N., 1985, Calcic soils of the sandstone petrology, and depositional southwestern : Geological history of the Albuquerque basin, central Society of America Special Paper 203, p. 1- New Mexico: Geological Society of 21. America Special Paper 291, p. 73-81. Machette, M.N., 1986, History of Quaternary Lozinsky, R.P., and Hawley, J.W., 1986a, Upper offset and paleoseismicity along the La Cenozoic of south- Jencia fault, central Rio Grande rift, New central New Mexico: New Mexico Mexico, Seismological Society of America Geological Society, Guidebook 37, p. 239- Bulletin, v. 76, p. 259-272. 247. Machette, M.N., Long, T., Bachman, G.O., and Lozinsky, R.P., and Hawley, J.W., 1986b, The Timbel, N.R., 1997, Laboratory data for Palomas Formation of south-central New calcic soils in central New Mexico: Mexico-a formal definition: New Mexico Background information for mapping Geology, v. 8, n. 4, p. 73-82. Quaternary deposits in the Albuquerque Lozinsky, R.P., and Hawley, J.W., 1991, Basin: New Mexico Bureau of Mines and Cenozoic structural evolution and Mineral Resources, Circular 205, 63 p. depositional history in three Rio Grande rift Machette, M.N., Personius, S.F., Kelson, K.I., basins, central and southern New Mexico Haller, K.M., and Dart, R.L., 1998, Map and [abstract]: Geological Society of America, data for Quaternary faults and folds in New Abstracts with Programs, v. 23, n. 4, p. A- Mexico: U.S. Geological Survey Open-File 44. Report 98-821, 443 p., 1 pl. Lucas, S. G. and Williamson, T. E., 1988, Late Mack. G.H., Love, D.W., and Seager, W.R., Pleistocene (Rancholabrean) mammals from 1997, Spillover models for axial rivers in the Edith Formation, Albuquerque, New regions of continental extension: the Rio Mexico: New Mexico Journal of Science, v. Mimbres and Rio Grande in the southern 28, p. 51–58. Rio Grande rift, USA: Sedimentology, v. 44, Lundahl, A., and Geissman, J.W., 1999, p. 637-652. Paleomagnetism of the early Oligocene Mack, G. H., Salyards, S. L., McIntosh, W. C., mafic dike exposed in Placitas, northern and Leeder, M. R., 1998, Reversal termination of the Sandia Mountains: New magnetostratigraphy and radioisotopic Mexico Geological Society, Guidebook 50, geochronology of the Plio-Pleistocene Camp p. 8-9. Rice and Palomas Formations, Southern Rio Luedke, R.G., and Smith, R.L., 1978, Map Grande rift: New Mexico Geological showing distribution, composition, and age Society, Guidebook 49, p. 229-236. of late Cenozoic volcanic centers in Arizona Maldonado, F., Connell, S.D., Love, D.W., and New Mexico: U.S. Geological Survey, Grauch, V.J.S., Slate, J.L., McIntosh, W.C., Miscellaneous Investigations Series, I-1091- Jackson, P.B., and Byers, F.M., Jr., 1999, A. Neogene geology of the Isleta Reservation Machette, M.N., 1978a, Dating Quaternary faults and vicinity, Albuquerque Basin, New in the southwestern United States using Mexico: New Mexico Geological Society buried calcic paleosoils: U.S. Geological Guidebook 50, p. 175-188. Survey, Journal of Research, v. 6, p. 369- Manley, K. M., 1978, Geologic map of the 381. Bernalillo NW quadrangle, Sandoval Machette, M. N., 1978b, Geologic map of the County, New Mexico: U.S. Geological San Acacia quadrangle, Socorro County, Survey quadrangle Map GQ-1446, scale New Mexico: U. S. Geological Survey, 1:24,000. Geologic quadrangle Map GQ 1415, scale May, J.S., and Russell, L.R., 1994, Thickness of 1:24,000. the syn-rift Santa Fe Group in the Machette, M. N., 1978c, Late Cenozoic geology Albuquerque Basin and its relation to of the San Acacia-Bernardo area: New structural style: Geological Society of Mexico Bureau of Mines and Mineral America, Special Paper 291, p. 113-123. Resources, Circular 163, p. 135-137.

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McMahon, D., Harrison, J.B.J., and Muldavin, Pazzaglia, F.J., Woodward, L.A., Lucas, S.G., E., 1998, Soil spatial variability within a Anderson, O.J., Wegman, K.W., and Estep, first order semi-arid drainage basin, J.W., 1999b, Phanerozoic geologic evolution Sevilleta National Wildlife Refuge, New of the Albuquerque area: New Mexico Mexico, USA, in J.B.J. Harrison, compiler, Geological Society, Guidebook 50, p. 97- Soil, Water, and Earthquakes around 114. Socorro, New Mexico: Rocky Mountain Peate, D. W., Chen, J. H., Wasserburg, G. J., and Cell, Friends of the Pleistocene, 36 p. Papanastassiou, D. A., 1996, 238U-230Th Morgan, G.S., Lucas, S.G., Sealey, P.L., dating of a geomagnetic excursion in Connell, S.D., Love, D.W., 2000, Pliocene Quaternary basalts of the Albuquerque (Blancan) vertebrates from the Palomas volcanoes field, New Mexico (USA): Formation, Arroyo de la Parida, Socorro Geophysical Research Letters, v. 23, n. 17, basin, central New Mexico [abstract]: New p. 2271-2274. Mexico Geology, v. 22, n. 2, p. 47. Perkins, M.E., Brown, F.H., Nash, W.P., Morrison, R.B., 1991, Introduction, in Morrison, McIntosh, W., Williams, S.K., 1998, R.B., ed., Quaternary nonglacial geology: Sequence, age, and source of silicic fallout conterminous U.S.: Geological Society of tuffs in middle to late Miocene basins of the America, The Geology of , v. northern Basin and Range Province: K-2, p. 1-12. Geological Society of America Bulletin, v. Mozley, P.S. and Davis, J.M., 1996. Relationship 110, n. 3, p. 344-360. between oriented calcite concretions and Personius, S. F., Machette, M. N., and Stone, B. permeability correlation in an alluvial D., 2000, Preliminary geologic map of the aquifer, Sierra Ladrones Formation, New Loma Machette quadrangle, Sandoval Mexico: Journal of Sedimentary Research, County, New Mexico: U.S. Geological v. 66, p. 11-16. Survey, Miscellaneous Field Investigations, (NACSN) North American Commission on MF-2334, scale 1:24,000, ver. 1.0. Stratigraphic Nomenclature, 1983, North Read, A. S., Rogers, J., Raiser, S., Smith, G., American Stratigraphic Code: American Koning, D. J., and Bauer, P.W., 2000, Association of Petroleum Geologists Geology of the Santa Fe 7.5-minute Bulletin, v. 67, n. 5, p. 841-875. quadrangle, Santa Fe County, New Mexico: Needham, C. E., 1936, Vertebrate remains from New Mexico Bureau of Mines and Mineral Cenozoic rocks: Science, v. 84, p. 537. Resources Open-File Geologic Map OF-GM Osburn, G.R., 1983, Socorro County geologic 32, scale 1:12,000. map: New Mexico Bureau of Mines and Reiche, P., 1949, Geology of the Manzanita and Mineral Resources, Open-file report 238, 14 north , New Mexico: p., 1 pl. scale 1:200,000. Geological Society of America, Bulletin, v. Osburn, G.R., and Chapin, C.E., 1983, 60, p. 1183-1212. Nomenclature for Cenozoic rocks of Reilinger, R., and Oliver, J., 1976, Modern uplift northeast Mogollon-Datil volcanic field, associated with a proposed magma body in New Mexico: New Mexico Bureau of Mines the vicinity of Socorro, New Mexico: and Mineral Resources, Stratigraphic Chart Geology, v. 4, p. 573-586. 1. Reinhart, E. J., and Sanford, A. R., 1981, Upper Panter, K., Hallett, B., Love, D., McKee, C., and crustal structure of the Rio Grande rift near Thompson, R., 1999, A volcano revisited: A Socorro, New Mexico, from inversion of preliminary report of the geology of Los micro earthquake S-wave reflections: Lunas Volcano, central New Mexico [abs.]: Seismological Society of America Bulletin, New Mexico Geology, v. 21, p. 44. v. 71, p. 437-450. Pazzaglia, F.J., Connell, S.D., Tedford, R.H., Russell, L.R., and Snelson, S., 1994, Structure Hawley, J.W., Personius, S., Smith, G.A., and tectonic of the Albuquerque basin Cather, S.M., Lucas, S.G., Hester, P., segment of the Rio Grande rift: Insights Gilmore, J., and Woodward, L.A., 1999a, from reflection seismic data, in Keller, G.R., Second-day trip 2 road log, Albuquerque to and Cather, S.M., eds., Basins of the Rio San Ysidro, Loma Creston, La Ceja, and Grande rift: structure, stratigraphy, and Sand Hill fault: New Mexico Geological tectonic setting: Geological Society of Society, Guidebook 50, p. 47-66. America Special Paper 291, p. 83-112.

52 NMBMMR OFR 454A

Sanford, A. R., and Long, L.T., 1965, Tedford, R. H., 1982, Neogene stratigraphy of Microearthquake crustal reflections, the northwestern Albuquerque Basin: New Socorro, New Mexico: Seismological Mexico Geological Society Guidebook 33, Society of America Bulletin, v. 55, p. 579- p. 273-278. 586. Tedford, R. H. and Barghoorn, S., 1997, Shackley, M. S., 1998, Geochemical Miocene mammals of the Española and differentiation and prehistoric procurement Albuquerque Basins, north central New of obsidian in the Mount Taylor volcanic Mexico: New Mexico Museum of Natural field, northwest New Mexico: Journal of History and Science Bulletin 11, p. 77-96. Archaeological Science, v. 25, p. 1073- Tedford, R.H., and Barghoorn, S., 1999, Santa 1082. Fe Group (Neogene), Ceja del Rio Puerco, Smartt, R.A., Lucas, S.G., Hafner, D.J., 1991, northwestern Albuquerque Basin, Sandoval The giant Bison (Bison latifrons) from the County, New Mexico: New Mexico middle Rio Grande valley of New Mexico: Geological Society, Guidebook 50, p. 327- The Southwestern Naturalist, v. 36., n. 1, p. 335. 136-137. Titus, F. B., Jr., 1963, Geology and ground-water ?: New Mexico Geological conditions in eastern Valencia County, New Society, Guidebook 47, p. 219-224. Mexico: New Mexico Bureau of Mines and Smith, G.A., and Kuhle, A.J., 1998, Mineral Resources, Ground-Water Report 7, Hydrostratigraphic implications of new 113 p. geologic mapping in the Santo Domingo Treadwell-Steitz, C., 1998, Palo Duro Wash Basin, New Mexico: New Mexico Geology, chronosequence: Landscapes and soils in a v. 20, n. 1, p. 21-27. semi-arid fluvial system, in J.B.J. Harrison, Smith, G.A., Kuhle, A.J., McIntosh, W.C., 2001, compiler, Soil, Water, and Earthquakes Sedimentologic and geomorphic evidence around Socorro, New Mexico: Rocky for seesaw subsidence of the Santo Domingo Mountain Cell, Friends of the Pleistocene, accommodation-zone basin, Rio Grande 23 p. Rift, New Mexico: Geological Society of Woldegabriel, G., Laughlin, A. W., Dethier, D. America Bulletin, v. 113, n. 5, p. 561-574 P., and Heizler, M., 1996, Temporal and Smith, G.A., and Lavine, A., 1996, What is the geochemical trends of in White Rock Spiegel, Z., 1961, Late Cenozoic sediments Canyon and the , Jemez of the lower Jemez region: New Mexico Volcanic Field, New Mexico, USA: New Geological Society, Guidebook 12, p.132- Mexico Geological Society, Guidebook 47, 138. p. 251-261 Stearns, C. E., 1953a, Tertiary geology of the Woodward, L. A. and Ruetschilling, R. L., 1976, Galisteo-Tonque area, New Mexico: Geology of San Ysidro quadrangle, New Geological Society of America Bulletin, v. Mexico: New Mexico Bureau of Mines and 64, p. 459-508. Mineral Resources, Geologic Map 37, scale Stearns, C. E., 1953b, Early Tertiary volcanism 1:24,000. in the Galisteo–Tonque area, north-central Woodward, L. W. and Menne, B., 1995, Down- New Mexico: American Journal of Science, plunge structural interpretation of the v. 251, p. 415–452. Placitas area, northwestern part of Sandia Stearns, C.E., 1979, New K-Ar dates and the late uplift, central New Mexico–implications for Pliocene to Holocene geomorphic history of tectonic evolution of the Rio Grande rift: the central Rio Grande region, New Mexico: New Mexico Geological Society, Discussion: Geological Society of America Guidebook 47, p. 127-133. Bulletin, v. 90, n. 8, p. 799-800. Wright, H. E., Jr., 1946, Tertiary and Quaternary Stewart, J.H., and 19 others, 1998, Map showing geology of the lower Puerco area, New Cenozoic tilt domains and associated Mexico: Geological Society of America structural features, western North America: Bulletin, v. 57, p. 383-456. Geological Society of America, Special Young, J. D., 1982, Late Cenozoic geology of Paper 323, plate 1. the lower Rio Puerco, Valencia and Socorro Tedford, R. H., 1981, Mammalian biochronology Counties, New Mexico [M.S. thesis]: of the late Cenozoic basins of New Mexico: Socorro, New Mexico Institute of Mining Geological Society of America Bulletin, and Technology, Socorro, 126 p. v.92, p.1008-1022.

53 STRATIGRAPHY AND TECTONIC DEVELOPMENT OF THE ALBUQUERQUE BASIN, CENTRAL RIO GRANDE RIFT

FIELD-TRIP GUIDEBOOK FOR THE GEOLOGICAL SOCIETY OF AMERICA ROCKY MOUNTAIN-SOUTH CENTRAL SECTION MEETING, ALBUQUERQUE, NM PRE-MEETINNG FIELD TRIP

MINI-PAPERS

Compiled and edited by

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office 2808 Central Ave. SE, Albuquerque, NM 87106

SPENCER G. LUCAS New Mexico Museum of Natural History and Science 1801 Mountain Rd. NW, Albuquerque, NM 87104

DAVID W. LOVE New Mexico Bureau of Mines and Mineral Resources 801 Leroy Place, Socorro, NM 8701

Open-File Report 454B

Initial Release: April 27, 2001 Revised June 11, 2001

New Mexico Bureau of Mines and Mineral Resources New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801 STRATIGRAPHY AND TECTONIC DEVELOPMENT OF THE ALBUQUERQUE BASIN, CENTRAL RIO GRANDE RIFT

FIELD-TRIP GUIDEBOOK FOR THE GEOLOGICAL SOCIETY OF AMERICA ROCKY MOUNTAIN-SOUTH CENTRAL SECTION MEETING, ALBUQUERQUE, NM PRE-MEETINNG FIELD TRIP

REPRINTED PAPERS

NEW MEXICO GEOLOGICAL SOCIETY GUIDEBOOK 50

EDITED BY

FRANK J. PAZZAGLIA Department of Earth and Planetary Sciences University of New Mexico Albuquerque, NM 87131

SPENCER G. LUCAS New Mexico Museum of Natural History and Science 1801 Mountain Rd. NW, Albuquerque, NM 87104

Reprinted with permission from the New Mexico Geological Society NMBMMR 454B REVISIONS TO GUIDEBOOK AND MINI-PAPERS

This field-guide accompanied a pre-meeting field trip of the Geological Society of America Rocky Mountain and South-Central Section conference in Albuquerque, New Mexico. A limited quantity of guidebooks and mini- paper compilations were produced for participants of this field trip. A number of typographical, grammatical, and editorial errors were found in this first version of the guidebook, mainly because of logistical constraints during preparation for the field trip. In the revised version, released on June 11, 2001, many errors have been corrected. Many photographs, figures, and maps, shown during the field trip but not included in the first version, are included in this revision. Numerous minor editorial changes and corrections have also been made to the guidebook mini- papers. The field-guide has been separated into two parts. Part A (open-file report 454A) contains the three-days of road logs and stop descriptions. Part B (open-file report 454B) contains a collection of mini-papers relevant to field-trip stops. The contents of the road logs and mini-papers have been placed on open file in order to make them available to the public as soon as possible. Revision of these papers is likely because of the on-going nature of work in the region. The papers have not been edited or reviewed according to New Mexico Bureau of Mines and Mineral Resources standards. The contents of this report should not be considered final and complete until published by the New Mexico Bureau of Mines and Mineral Resources. Comments on papers in this open-file report are welcome and should be made to authors. The views and preliminary conclusions contained in this report are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the State of New Mexico or the U.S. Government.

ACKNOWLEDGEMENTS

This field trip was supported by the New Mexico Bureau of Mines and Mineral Resources (P.A. Scholle, Director) and the New Mexico Museum of Natural History and Science. Much of the data presented during this field trip are from numerous open-file reports released by the New Mexico Bureau of Mines and Mineral Resources during the course of cooperative geologic mapping with the U.S. Geological Survey (New Mexico Statemap Project, P.W. Bauer, Program Manager). We are particularly grateful to the Pueblos of Zia, Isleta, Sandia, San Felipe, Santo Domingo, Jemez, and Santa Ana for granting access during many of the stratigraphic and mapping studies discussed during the field trip. In particular, we thank Mr. Peter Pino for enabling access to study the stratigraphically significant localities along the Rincones de Zia. We also thank Mr. Gary Nolan, Mr. Jerry Burke, and Mr. Mackie McClure for allowing access to the LaFarge and SunCountry Redimix gravel quarries near Bernalillo, New Mexico. We also thank Ms. Leanne Duree of the Ball Ranch for allowing access through their lands on Tanos Arroyo. We thank the New Mexico Geological Society for granting permission to reprint three papers from their 1999 Guidebook 50 entitled Albuquerque Geology (F.J. Pazzaglia and S.G. Lucas, eds). We especially thank V.J.S. Grauch for agreeing to present summaries of recent regional geophysical surveys of the Albuquerque Basin.

ii NMBMMR 454B

MINI-PAPER TABLE OF CONTENTS

Stratigraphy of the Albuquerque Basin, Rio Grande Rift, New Mexico: A Progress Report S.D. Connell...... A-1 Summary of Blancan and Irvingtonian (Pliocene and early Pleistocene) Mammalian Biochronology of New Mexico G.S. Morgan and S.G. Lucas ...... B-29 Miocene Mammalian Faunas and Biostratigraphy of the , Northern Albuquerque Basin, Sandoval County, New Mexico G.S. Morgan and S.G. Lucas ...... C-33 Pliocene Mammalian Biostratigraphy and Biochronology at Loma Colorada de Abajo, Sandoval County, New Mexico G.S. Morgan and S.G. Lucas ...... D-37 Plio-Pleistocene Mammalian Biostratigraphy and Biochronology at Tijeras Arroyo, Bernalillo County, New Mexico G.S. Morgan and S.G. Lucas ...... E-39 Lithostratigraphy and Pliocene Mammalian Biostratigraphy and Biochronology at Belen, Valencia County, New Mexico G.S. Morgan, S.G. Lucas, and D.W. Love ...... F-43 Pliocene Mammalian Biostratigraphy and Biochronology at Arroyo de la Parida, Socorro County, New Mexico G.S. Morgan and S.G. Lucas ...... G-47 Stratigraphy of the Lower Santa Fe Group, Hagan Embayment, North-Central New Mexico: Preliminary Results S.D. Connell and S,M. Cather ...... H-49 Stratigraphy of the Tuerto and Ancha Formations (Upper Santa Fe Group), Hagan and Santa Fe Embayments, North-Central New Mexico D.J. Koning, S.D. Connell, F.J. Pazzaglia, and W.C. McIntosh...... I-57 Stratigraphy of the Middle and Upper Pleistocene Fluvial Deposits of the Rio Grande (Post Santa Fe Group) and the Geomorphic Development of the Rio Grande Valley, Northern Albuquerque Basin, North-Central New Mexico S.D. Connell and D.W. Love...... J-67 Preliminary Interpretation of Cenozoic Strata in the Tamara No. 1-Y Well, Sandoval County, North-Central New Mexico S.D. Connell, D.J. Koning, and N.N. Derrick...... K-79 Guide to the Geology of the Eastern Side of the Rio Grande Valley along Southbound I-25 from Rio Bravo Boulevard to Bosque Farms, Bernalillo and Valencia Counties, New Mexico D.W. Love, S.D. Connell, N. Dunbar, W.C. McIntosh, W.C. McKee, A.G. Mathis, P.B. Jackson-Paul, J. Sorrell, and N. Abeita...... L-89 Pliocene and Quaternary Stratigraphy, Soils, and Tectonic Geomorphology of the Northern Flank of the Sandia Mountains, New Mexico: Implications for the Tectonic Evolution of the Albuquerque Basin Reprinted with permission from NMGS Guidebook 50 (Pazzagila and Lucas, 1999) S.D. Connell and W.G. Wells...... M Discussion of New Gravity Maps for the Albuquerque Basin Area Reprinted with permission from NMGS Guidebook 50 (Pazzagila and Lucas, 1999) V.J.S. Grauch, C.L. Gillespie, and G.R. Keller ...... N Principal Features of High-Resolution Aeromagnetic Data Collected near Albuquerque, New Mexico Reprinted with permission from NMGS Guidebook 50 (Pazzagila and Lucas, 1999) V.J.S. Grauch...... O

iii STRATIGRAPHY OF THE ALBUQUERQUE BASIN, RIO GRANDE RIFT, CENTRAL NEW MEXICO: A PROGRESS REPORT

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave., SE, Albuquerque, New Mexico 87106, [email protected]

INTRODUCTION and northern sub-basin, respectively (Fig 5; Grauch et al., 1999). Deep oil-well data indicate that the The Albuquerque Basin of central New Mexico Calabacillas sub-basin and northern part of the Belen is one of the largest sedimentary basins of the Rio sub-basin contain as much as 4-5 km of synrift basin Grande rift, a chain of linked, predominantly fill (Lozinsky, 1994). The Santo Domingo sub-basin asymmetric or half-graben extensional basins that is a graben with a complicated subsidence history extend south from central Colorado, through central that represents a zone of accommodation between the New Mexico, and into western Texas and northern Albuquerque and Española basins (Smith et al., Mexico (Hawley, 1978; Chapin and Cather, 1994). 2001). The Hagan embayment is a northeast-dipping The Albuquerque Basin is about 60 km long, and structural re-entrant between the San Francisco and about 55 km wide and strongly faulted on nearly all La Bajada faults that contains the oldest exposed sides (Fig. 1). The Albuquerque Basin also represents Santa Fe Group strata in the basin. a transitional tectonic feature, lying between the The boundaries among the major sub-basins are west-tilted Española and Socorro half-graben basins. complicated, however, regional gravity and oil-test The Albuquerque Basin sits between the data can constrain their locations. The southern topographically and structurally well expressed portion of the Belen sub-basin narrows to about 9-12 northern Rio Grande rift of northern New Mexico km in width near the confluence of the Rio Salado and southern Colorado, and the broader Basin and and Rio Grande. The boundary between the Belen Range to the south. Basins of the northern Rio and Calabacillas sub-basins are defined by a diffuse Grande rift tend to step eastward (Kelley, 1982), zone of accommodation where the direction of stratal whereas basins to the south form alternating block- tilts change across the Tijeras accommodation zone faulted basins and uplifts that characterize the Basin of Russell and Snelson (1994). Gravity data suggests and Range. that the northwest-trending Mountainview prong The Albuquerque Basin comprises a single (Hawley, 1996; Grauch et al., 1999) probably defines physiographic (Fig. 2) and tectonic feature the boundary between the Belen and Calabacillas (Woodward et al., 1978) that is segmented into a sub-basins. The boundary between the Calabacillas number of structural sub-basins and embayments and Santo Domingo sub-basins is quite diffuse and (Grauch et al., 1999). Isostatic gravity data and oil- recognized primarily on the basis of a broad north- test data (Fig. 2) indicates that the basin is segmented and northwest-trending gravity high marked by the into three major sub-basins (Cordell, 1978, 1979; Ziana structure (Kelley, 1977; Personius et al., 1999; Birch, 1982; Heywood, 1992; Grauch et al., 1999; Grauch et al., 1999) and Alameda structural Russell and Snelson, 1994; May and Russell, 1994; (monoclinal) zone. Other possible boundaries Lozinsky, 1994): the northern Santo Domingo, between these two sub-basins is the northeast- central Calabacillas, and southern Belen sub-basins. trending Loma Colorado zone (Hawley, 1996), which Sub-basin boundaries are somewhat diffuse and not is marked by a northeast-trending alignment of fault- universally accepted (Kelley, 1977; Lozinsky, 1994; terminations, where faults of a specific polarity of Hawley, 1996; Grauch et al., 1999). Sub-basins also movement (i.e., east-dipping) step over into faults contain somewhat different depositional packages of having the opposite sense of dip (and presumably the earlier rift-basin fill, whose lateral extent may be displacement). The Loma Colorado structural feature, influenced by sub-basin boundaries (Fig. 3; Cole et however, is not well expressed in the gravity data and al., 1999). Gravity data also shows a northwest appears to die out to the northeast. Another possible structural grain within the basin along sub-basin boundary between the Calabacillas and Santo boundaries (Fig. 2; Grauch et al., 1999). This Domingo sub-basins has also been proposed at the northwest trend is not readily apparent from surficial San Felipe graben (Lozinsky, 1994), between Santa geologic mapping and differs from the predominantly Ana Mesa and the Ziana structure; however, this north-trending structural grain of the basin (Fig. 4), graben is not well expressed in the gravity data and is suggesting that sub-basin boundaries are obscured by probably a minor feature within the Santo Domingo younger and less deformed basin fill. The Belen sub- sub-basin. basin comprises the southern half of the Albuquerque Basin, is complexly faulted, and has a westward stratal tilt. The dominantly east-tilted Calabacillas and Santo Domingo sub-basins comprise the central A-1 NMBMMR OFR 454B fault, a relatively young intrabasinal fault proposed by Russell and Snelson (1994). Their Rio Grande fault cuts the basin-bounding rift-flanking faults of the Sandia Mountains. Gravity (Grauch et al., 1999), geomorphic, and stratigraphic data (Connell and Wells, 1999; Connell et al., 1998a; Maldonado et al., 1999) questions the existence of this fault, which is buried by Quaternary alluvium. If the Rio Grande fault is not present beneath Albuquerque, then Russell and Snelson’s (1994) extension estimate would also be suspect. The lack of strong structural and topographic expression of the sub-basin boundaries indicated on Figure 2 suggests a complicated history of basin development that differs from the present configuration of faults. The northwest-trending structures are obscured by younger basin fill and may represent older structural boundaries; however, some of these structures deform Plio-Pleistocene sediments. Basin subsidence is controlled by numerous north-trending normal faults and relatively short, northeast-trending connecting faults that commonly form faulted relay ramps or transfer zones. Structural margins are typically defined by tilted footwall uplands, and basement-cored, rift-margin uplifts, such as the Sandia, Manzanita, Manzano, Los Pinos, and Ladron Mountains. These rift-bounding ranges Figure 1. Albuquerque Basin and surrounding areas. are locally overlain by Mississippian, Pennsylvanian Rift-flanking uplifts shown in black. Localities and Permian strata (Fig. 4) that provide a source of include: Rincones de Zia (rz), Ceja del Rio Puerco locally derived detritus for piedmont deposits. Other (cdr), Loma Barbon (lb), Arroyo Ojito (ao), Arroyo basin margins form escarpments, such as along the Piedra Parada (pp), Arroyo Popotosa (ap), Silver La Bajada fault and eastern edge of the Sierra Creek (sc), Trigo Canyon (tc), Espinaso Ridge (es), Lucero, which form footwall uplands of moderate White Rock Canyon (wr), El Rincon (er), Peralta relief and are underlain by Pennsylvanian-Paleogene Canyon (pc), Sierra Ladrones (sl), La Joya (lj), rocks. The northwestern margin is topographically Chamisa Mesa (cm), Tijeras Arroyo (ta), Gabaldon subdued and defined by faults such as the Moquino badlands (gb), and Hell Canyon (hc). Volcanic fault in the Rio Puerco valley (Kelley, 1977; Tedford features include the diabase of Mohinas Mountain and Barghoorn, 1999). The eastern structural margin, (MM), trachyandesite at San Acacia (SA), Cat Mesa near Albuquerque, New Mexico, is defined by (CM), Wind Mesa (WM), Isleta volcano (IV), basalt roughly north-trending faults 1-3 km of basinward at Black Butte (BB), and Los Lunas Volcano (LL). normal slip (Cordell, 1979; Russell and Snelson, Oil-test wells (indicated by black triangles) include: 1994). Shell Santa Fe Pacific #1 (sf1), Shell Isleta #1 (i1), Inception of the Rio Grande rift began during Davis Petroleum Tamara #1-Y (dpt), Shell Isleta #2 late Oligocene time (Chapin and Cather, 1994; Smith, (i2), Burlington Resources Kachina #1 (bk1), 2000; Kautz et al., 1981; Bachman and Mehnert, TransOcean Isleta #1 (to1), and Davis Petroleum, 1978; Galusha, 1966) as broad fault-bounded, Angel Eyes (dpa). Major Paleogene volcanic fields in internally drained basins began to receive sediment New Mexico and southern Colorado include: (Chapin and Cather, 1994). Stratal accumulation Mogollon-Datil volcanic field (MDvf), San Juan rates, calculated from scattered and sparsely dated volcanic field (SJvf), Jemez volcanic field (Jvf), and sections indicate late Oligocene-middle Miocene (Lvf). stratal accumulation rates (not adjusted for compaction) of about 72-83 m/m.y. (Tedford and The Albuquerque Basin was interpreted to have Barghoorn, 1999; Connell and Cather, this volume) undergone about 17% extension in the Calabacillas for sediments near the basin margins. During late and northern Belen sub-basins, near Albuquerque, Miocene times, Lozinsky (1994) estimated an and about 28% in the Belen sub-basin, near accumulation rate of about 600 m/m.y., which is Bernardo, New Mexico (Russell and Snelson, 1994). considerably greater that earlier rates. During The extension estimate for the northern part of the Pliocene time, the basins filled and became linked to basin is based on the presence of the Rio Grande adjoining basins with the onset of through-flowing

A-2 NMBMMR OFR 454B drainages of the ancestral Rio Grande fluvial system. the preservation of a number of local tops to the Stratal accumulation rates have only been estimated Santa Fe Group (Connell et al., 2000). During the in a few places and suggest a much slower rate of later part of the early Pleistocene (between 1.3-0.6 accumulation, perhaps less than about 100 m/m.y. Ma), the ancestral Rio Grande began to incise deeply into Plio-Pleistocene basin fill to form the present river valley (Connell et al., 2000; Gile et al., 1981). Aggradation locally persisted into middle Pleistocene time along the front of the Manzanita and Manzano Mountains where tributary drainages were not integrated with the Rio Grande (Connell et al., 2000). The cause of this long-term entrenchment may be the result of: (1) drainage integration in the San Luis Basin of north-central New Mexico and south-central Colorado (Wells et al., 1987); (2) integration of the Rio Grande with the Gulf of Mexico (Kottlowski, 1953); (3) regional uplift (Bachman and Mehnert, 1978); or (4) shift in regional climate (Dethier et al., 1988). Results of recent (published and unpublished) geologic mapping, stratigraphic, geomorphic, subsurface, radioisotopic, and biostratigraphic studies are reviewed in this overview of the stratigraphy of the Albuquerque Basin. This paper attempts to summarize results of mapping of over 60% of the basin that has occurred since 1994. Sedimentologic studies of basin-fill strata in the Albuquerque Basin and the Socorro region have been integrated in order to illustrate general sediment dispersal patterns (Bruning, 1973; Love and Young, 1983; Connell et al., 1999; Lozinsky and Tedford, 1991; Maldonado et al., 1999; Tedford and Barghoorn, 1999; Smith and Kuhle, 1998a; Smith et al., 2001). Geomorphic studies have delineated major constructional surfaces of the Santa Fe Group (Machette, 1985; Connell and Wells, 1999; Dethier, 1999; Maldonado et al., 1999). Subsurface data primarily involve deep oil-test and shallower water-well data (Lozinsky, 1994; Hawley, 1996; Hawley et al., 1995; Connell et al., 1998a; Cole et al., 1999), and regional gravity and aeromagnetic surveys (Grauch, 1999; Grauch et al., 1999; U.S. Geological Survey et al., 1999; Heywood, 1992). Sub-basin boundaries are defined by broad, generally discontinuous zones of high gravity that are Figure 2. Shaded-relief image of the Albuquerque interpreted as structurally higher intrabasinal fault Basin and vicinity showing contours of the isostatic blocks (Hawley, 1996, p. 12; Cole et al., 1999; residual gravity anomaly as white contours (modified Grauch et al., 1999). from Grauch et al., 1999). Approximate boundaries Radioisotopic dates are from volcanic and of major sub-basin depressions are shown by bold volcaniclastic rocks that are interbedded with, dashed lines. Major structural benches and underlie, or are overlain by, basin-fill. These dated intrabasinal positive areas include the Hubbell bench volcanic rocks include mafic lava flows, ash-flow and Ziana structure (Personius et al., 2000), tuffs, fallout ashes and tuffs, and fluvially recycled Mountainview Prong (MVP) and Laguna bench pumice and tuff clasts in gravelly beds. Potassium- (terminology of Hawley, 1996), and Wind Mesa horst argon (K/Ar) dates are reported here to a precision of (WMH, Maldonado et al., 1999). Base image 0.1 Ma; 40Ar/39Ar dates are reported to a precision of produced from U.S. Geological Survey National 0.01 Ma, except where noted. Vertebrate fossils have Elevation Database DEM data. been collected from numerous sites (Morgan and Lucas, 2000). Many of the fossils found in the basin Cessation of widespread basin-fill deposition of have relatively long temporal ranges that limit precise the Santa Fe Group occurred at different times in stratigraphic correlation. In older deposits of the different parts of the Albuquerque Basin, resulting in A-3 NMBMMR OFR 454B Santa Fe Group, magnetostratigraphic studies permit arkose and conglomerate that formed a volcaniclastic correlation to other dated stratigraphic sections apron around the neighboring Ortiz Mountains- (Tedford and Barghoorn, 1999). Integration of Cerrillos Hills magmatic centers, which erupted various chronologic data greatly improves the between 26-37 Ma (Erskine and Smith, 1993; Kautz chronologic resolution of basin-fill strata. et al., 1981). Sandstone contains sparse to no quartz The main goal of this summary is to present an grains (Kautz et al., 1981). The updated regional correlation and synthesis of the conformably overlies the and is Santa Fe Group in the Albuquerque Basin. Recent unconformably overlain by quartz-bearing lithic insights on the stratigraphy and sedimentology of the arkose and feldspathic arenite and volcanic-bearing basin-fill are presented in detail, primarily to clarify a conglomerate of the informally defined Tanos and rather confusing history of stratigraphic usage. Blackshare Formations of the lower Santa Fe Group (Connell and Cather, this volume; Cather et al., PRE-SANTA FE GROUP STRATIGRAPHY 2000). The unit of Isleta #2 is an informal stratigraphic Pre-rift strata are exposed along basin margins term applied to 1787-2185 m of upper Eocene- and in deep oil-test wells. These deposits include the Oligocene strata recognized in at least six deep oil- Paleogene Galisteo and Diamond Tail formations, test wells in the basin (Lozinsky, 1994; May and and Oligocene volcanic and volcaniclastic rocks Russell, 1994). This volcanic-bearing succession is derived from volcanic fields in New Mexico and buried by up to 4400 m of Santa Fe Group deposits southern Colorado, such as the Mogollon-Datil, San (Lozinsky, 1994). Two recent oil-test wells Juan, and Latir volcanic fields. The Galisteo and (Burlington Resources Kachina #1, and Davis Diamond Tail formations are arkosic to subarkosic Petroleum Tamara #1-Y) also encountered this unit in and typically lack volcanic detritus. These formations the Calabacillas sub-basin. The unit of Isleta #2 is record deposition by major rivers draining Laramide composed of purplish-red to gray, subarkosic, uplifts during Paleocene and Eocene times (Lucas et volcanic-bearing sandstone with mudstone interbeds, al., 1997; Abbott et al., 1995; Ingersoll et al., 1990; and is therefore quite different from the composition Gorham and Ingersoll, 1979). Deposition of the of the Espinaso Formation. It is quite quartz rich Galisteo Formation was interrupted by widespread (Q=68±9%, Lozinsky, 1994). The quartzose emplacement of intermediate to silicic volcanic rocks character and distance from known Oligocene-aged during late Eocene and Oligocene time; silicic volcanic centers, and may suggest compositional volcanism was typically dominated by ignimbrite maturation of instable volcanic constituents from eruptions from caldera complexes and eruptive these distant centers, which has been proposed to centers scattered throughout the southwestern United explain petrographic differences between the Santa States and Mexico. Fe Group and (Large and In central and northern New Mexico, these Ingersoll, 1997). Abundant quartz could also suggest Oligocene eruptive centers include: the Ortiz possible contributions and mixing from other quartz- porphyry belt (Ortiz Mountains and Cerrillos Hills), rich sources, such as on the adjacent Colorado west of Santa Fe, the Mogollon-Datil volcanic field Plateau (see Stone, 1979). An ash-flow tuff of western New Mexico, San Juan volcanic field of encountered in the unit’s namesake well was K/Ar southern Colorado, and Latir volcanic field, just north dated at 36.3±1.8 Ma (May and Russell, 1994), of Taos, New Mexico. These volcanic and indicating a pre-rift heritage for the unit of Isleta #2. volcaniclastic rocks are discontinuously exposed Oligocene strata were not recognized on the along the southern and northeastern margins of the Ziana structure (Shell Santa Fe Pacific #1; Black and basin and are differentiated into three units: the Hiss, 1974). The Ziana structure is about 30 km west Espinaso Formation, unit of Isleta #2, and volcanic of Espinaso Ridge and marks the boundary between and volcaniclastic units of the Datil Group and the Calabacillas and Santo Domingo sub-basins. The Mogollon-Datil volcanic field, including the La Jara Davis Tamara #1-Y well, drilled about 6 km Peak basaltic andesite The Santa Fe Group northwest of the Santa Fe Pacific #1 well, fully commonly overlies these Oligocene volcanic rocks, penetrated the Santa Fe Group section. Examination except along the northwestern part of the Calabacillas of the cuttings from the Tamara well suggests the sub-basin where the Santa Fe Group overlies deposits presence of a lower 455-481-m thick interval of sand of the upper Galisteo Formation (Lucas, 1982). stratigraphically below the Piedra Parada Member The Espinaso Formation crops out along suggests the presence of either an earlier sedimentary Espinaso Ridge in the Hagan embayment, where it is unit between the Piedra Parada Member and the about 430 m thick. The Espinaso Formation is a lithic Galisteo Formation.

A-4 NMBMMR OFR 454B

Figure 3. Schematic stratigraphic correlation diagram of the Albuquerque Basin and other basins of the Rio Grande rift, illustrating age-constraints and the North American Land Mammal “ages.” Volcanic units include, the upper (UBT) and lower (LBT) Bandelier Tuff members of the . The Cañada Pilares Member of the Zia Formation (CPM) is locally recognized along the northwestern margin of the Calabacillas sub-basin. The gravel of Lookout Park (GLP) of Smith and Kuhle (1998a, b) is an unconformity-bounded gravel preserved on the hanging wall hinge of the Santo Domingo sub-basin.

A-5 NMBMMR OFR 454B

Figure 4. Generalized geologic map of the Albuquerque Basin, modified from Hawley (1996 and Hawley et al., 1995), with additional modifications from Osburn (1983), Machette et al. (1998), Maldonado et al. (1999), Connell (1997), Connell and Wells (1999), Connell et al. (1995, 1999), Cather and Connell (1998), Cather et al. (2000), Love and Young (1983), Personius et al. (2000), Smith and Kuhle (1998a, b), Lozinsky and Tedford (1991), Smith et al. (1970), and Goff et al. (1990). Line A-A’ on the figure denotes the location of cross section on Figure 5. Faults include the Moquino (Mof), San Ysidro (SYf), San Francisco (SFf), Tijeras (Tfz), Hubbell Spring (HSf), Comanche (Cmf), (Cof), and Loma Peleda (LPf) faults.

A-6 NMBMMR OFR 454B

Figure 5. Generalized geologic cross section of Calabacillas sub-basin drawn at latitude of Paseo del Norte Boulevard in Albuquerque (Fig. 4). Gray triangles denote locations of selected wells that were used provide stratigraphic control for the cross section. The Llano de Albuquerque represents a broad mesa and local constructional top of the , and is the interfluve between the Rio Puerco and Rio Grande. Cross section illustrates projected depths of Proterozoic crystalline rocks (XY), pre-Tertiary (pT) sedimentary deposits, Paleogene volcanic and nonvolcanic deposits (Tl), and synrift basin fill of the Santa Fe Group (Ts, QTs). Oligo-Miocene deposits of the Santa Fe Group (Ts) include the Zia and Arroyo Ojito formations and undivided strata beneath Albuquerque, NM. Plio-Pleistocene deposits of the upper Santa Fe Group (QTs) include the upper Arroyo Ojito Formation and Sierra Ladrones Formation. Unit QTs comprises much of the aquifer used by the City of Albuquerque east of the Llano de Albuquerque. Major faults of the western margin include the Moquino (Mfz), Sand Hill (SHfz), San Ysidro (SYfz), and Zia (Zfz) fault zones. Major eastern-margin fault zones include the East Heights (EHfz), Rincon (Rfz), and Sandia (Sfz) fault zones.

Cenozoic strata in the Tamara well are 1978). This Oligocene volcanic succession is petrographically distinct from the Abiquiu Formation dominated by intermediate and silicic tuffs that are (Connell, Koning, and Derrick, this volume). commonly densely welded. The upper part of this Additional study, however, is required to determine succession generally becomes slightly more the spatial relationships among these possible Oligo- heterolithic and contains a greater abundance of Miocene deposits in the northwest Calabacillas sub- basaltic and basaltic andesite rocks (Osburn and basin with Abiquiu Formation sediments in the Chapin, 1983). Chama sub-basin. This lower interval in the Tamara An exposure of volcaniclastic sediments was well may be correlative to the unit of Isleta #2, which recognized along the western front of the Manzano is about 2.2 km thick in the Shell Federal Mountains, near the mouth Trigo Canyon (Kelley, #1, about 25-30 km to the southeast. Correlation of 1977). No crystalline rocks derived from the western this lower interval to the unit of Isleta #2 is supported front of the Manzano Mountains are recognized in by the presence of a discontinuous layer of Oligocene these deposits (Karlstrom et al., 2001). A basalt flow volcanic pebbles and cobbles at the exposed contact near Trigo Canyon, at the front of the Manzano between the Zia Formation and subjacent strata along Mountains, was originally K/Ar dated at 21.2±0.8 Ma the western basin margin. The presence of this by Bachman and Mehnert (1978). Kelley (1977) volcanic gravel at this contact indicates the presence considered this basalt to be a sill within the Datil of a formerly more extensive Oligocene deposit that Group. An 40Ar/39Ar date of 26.20±0.18 Ma has subsequently been eroded. (Karlstrom et al., 2001) for this flow indicates that Deposits of the Mogollon-Datil volcanic field the previous K/Ar date is too young and may have comprise an areally extensive succession of upper been affected by alteration. Lozinsky (1988) Eocene-Oligocene (27-34 Ma; Osburn and Chapin, demonstrated the subaerial nature of this flow. On the 1983), ash-flow tuffs, basaltic lavas, and basis of the K/Ar age and slightly heterolithic volcaniclastic deposits exposed in the southern Belen character of the volcanic gravel, he assigned these sub-basin. Eocene outflow tuffs were assigned to the strata to the Popotosa Formation. The new date upper Eocene Datil Group. A variety of Oligocene indicates that this flow is similar in age to the pre-rift tuffs and cauldron-fill units overlie the Datil Group Cerritos de las Minas flow (Machette, 1978a) and lies and include the 33.1 Ma Hells Mesa Tuff, 28.4 Ma within the age range of the La Jara Peak basaltic Lemitar Tuff, 26-27 Ma La Jara Peak basaltic andesite (Osburn and Chapin, 1983). The Leroy andesite and South Canyon Tuff (K/Ar dates reported Bennett-Aguayo Comanche #1 oil-test, drilled a few in Osburn and Chapin, 1983; Bachman and Mehnert, kilometers north of Trigo Canyon, encountered at

A-7 NMBMMR OFR 454B least 350 m of similarly described volcanic and conflicting and overlapping usage by previous volcaniclastic sediments (from scout ticket; workers. Karlstrom et al., 2001). A 26 Ma date for a such a thick succession of volcanic sediments and the lack Volcanic Rocks of the Jemez Mountains of locally derived detritus from the western front of the Manzano mountains supports correlation to The Jemez Mountains were formed by multiple subjacent Oligocene volcanic rocks, rather than the volcanic eruptions since middle Miocene time. They Popotosa Formation; however, additional study is lie on a northeast-trending zone of Quaternary and needed to resolve the stratigraphic assignment of Pliocene volcanic fields called the Jemez lineament these conglomeratic beds. (Mayo, 1958). The volcanic rocks of the southern Jemez Mountains are placed into the Keres, SANTA FE GROUP STRATIGRAPHY AND Polvadera, and Tewa Groups (Figs. 3-4; Bailey et al., CHRONOLOGY 1969; Smith et al., 1970). The southern Jemez Mountains are largely composed of the Miocene Deposits of the Santa Fe Group (Spiegel and . The central and northern Jemez Baldwin, 1963) have been differentiated into two, Mountains contain the Miocene-Pliocene Polvadera and in some places three, informal sub-groups. The Group, and the Plio-Pleistocene Tewa Group. The lower Santa Fe Group records deposition in internally Keres and Polvadera groups represent volcanic drained basins (bolsons) where streams terminated events prior to the emplacement of the areally onto broad alluvial plains with ephemeral or extensive Tewa Group, which covers much of the intermittent playa lakes bounded by piedmont Jemez Mountains. Volcanic strata were erupted deposits derived from emerging basin-margin uplifts. contemporaneously with subsidence in the Española Upper Santa Fe Group strata record deposition in Basin and Abiquiu embayment (Chama sub-basin). externally drained basins where perennial streams The Keres Group contains basaltic, andesitic, and rivers associated with the ancestral Rio Grande dacitic, and rhyolitic volcanic rocks, which are fluvial system flowed toward southern New Mexico. subdivided into the Canovas Canyon Rhyolite (12.4- The middle sub-group or formation is transitional 8.8 Ma; Gardner et al., 1986), Paliza Canyon between the lower interval, representing deposition Formation (13.2-7.4 Ma; Gardner et al., 1986), and within internally drained basins, and the upper Bearhead Rhyolite (7.1-6.2 Ma; Gardner et al., 1986). interval, representing deposition in an externally The Paliza Canyon Formation is lithologically drained basin. Deposition ceased during Pleistocene variable and contains basaltic, andesitic, and dacitic time, when the Rio Grande began to incise into the rocks that extend to within 2-4 km of the eastern earlier aggradational phase of the Santa Fe Group front of the Sierra Nacimiento (Smith et al., 1970). basin fill (Hawley et al., 1969). The 10.4±0.5 Ma basalt of Chamisa Mesa (Luedke Some workers (Bryan and McCann, 1937; and Smith, 1978) is included within the Paliza Spiegel, 1961; Lambert, 1968; Kelley, 1977) Canyon Formation (Gardner et al., 1986). The advocated a three-part subdivision of the Santa Fe Bearhead Rhyolite defines the top of the Keres Group Group in the Albuquerque area, principally because and contains the Peralta Tuff Member (6.16-6.96 Ma; of the presence of deposits that are transitional in Smith et al., 2001; Justet, 1999; McIntosh and Quade, character between the early phase of eolian, playa- 1995). lake, and fluviolacustrine sedimentation, and a later The in the central Jemez phase of fluvially dominated deposition. Mountains contains the Tschicoma Formation (6.9- Unfortunately, the use of a middle Santa Fe term has 3.2 Ma; Gardner et al., 1986), which represents been somewhat confusing, principally because of eruptions from a pre-Tewa Group volcanic edifice different lithostratigraphic definitions and situated near the central and northeastern part of the interpretations by various workers (see Connell et al., Jemez Mountains. 1999). Bryan and McCann (1937) proposed the term The Tewa Group is a voluminous succession of “middle red” for deposits that are mostly correlative rhyolitic tuff and volcanic flows that represent the to the Cerro Conejo Member (Connell et al., 1999). most recent stage of major volcanism in the Jemez Other workers (Spiegel, 1961; Lambert, 1968; Mountains. The Tewa Group includes the Valles Kelley, 1977) later extended the middle red to higher Rhyolite (0.1-1.0 Ma), Cerro Toledo Rhyolite (1.2- stratigraphic levels than proposed by Bryan and his 1.5 Ma), Bandelier Tuff, and Cerro Rubio quartz students (e.g., Wright, 1946; Bryan and McCann, latite (2.2-3.6 Ma) (Gardner et al., 1986). The 1937). The middle Santa Fe Group concept is useful Bandelier Tuff and Cerro Toledo Rhyolite are locally for hydrogeologic studies (Hawley et al., 1995; important stratigraphic units in the Albuquerque Hawley and Kernodle, in press); however, for the Basin. The early Pleistocene Bandelier Tuff is the purpose of this summary, this middle sub-group term most extensive unit and is subdivided into lower is avoided in order to avoid confusion with (Otowi and Guaje, 1.61 Ma) and upper (Tshirege and Tsankawi, 1.22 Ma) members (40Ar/39Ar dates of

A-8 NMBMMR OFR 454B Izett and Obradovich, 1994), which were deposited consisting of ephemeral or intermittent playa lake and during the collapse of the Toledo and Valles , local fluvial deposits; and (3) eolian facies consisting respectively. Primary and fluvially recycled tephra of of cross-bedded to massive, well sorted, fine-to the Bandelier Tuff are locally common in the medium-grained sandstone. Deposit composition uppermost part of the axial-fluvial facies of the Sierra reflects the of upland drainages and Ladrones Formation. contains sedimentary, volcanic, plutonic, and metamorphic rocks. Fluviolacustrine facies are Lower Santa Fe Group exposed in the western and southwestern parts of the Belen sub-basin and northeastern Santo Domingo The lower Santa Fe sub-Group ranges from late sub-basin and interfinger with piedmont facies Oligocene through late Miocene in age and records derived from emerging rift-flank uplifts. Eolian deposition in internally drained basins. These sandstone is exposed in the western and northwestern deposits are exposed along the basin margins and are parts of the Calabacillas sub-basin. The lateral either in fault contact with, or are unconformably boundary between eolian and fluviolacustrine facies overlain by, deposits of the upper Santa Fe Group; is not exposed, but lies between the Burlington however, the upper/lower sub-group boundary is Resources Kachina #1 well, which encountered well probably sub-basin within sub-basin depocenters sorted sandstone correlated to the Zia Formation (Cather et al., 1994). Lower Santa Fe Group (J.W. Hawley, 1998, oral commun.), and the Shell sediments record deposition in an internally drained Isleta #2 well, where mudstone and muddy sandstone bolson (Hawley, 1978). The lower Santa Fe Group of the Popotosa Formation are recognized (Lozinsky, contains three major facies that are subdivided into 1994). Thus, the lateral boundary between the Zia four formations (Zia, Popotosa, Tanos, Blackshare and Popotosa formations lies near the geophysically formations): (1) piedmont facies consisting of defined boundary of the Calabacillas and Belen sub- stream- and debris-flow deposits derived from basins, suggesting structural control over this facies uplands along the basin margin piedmont slope; (2) boundary (Cole et al., 1999). basin-floor fluviolacustrine (playa-lake) facies

Figure 6. Stratigraphic fence of Cenozoic deposits in the Calabacillas sub-basin. Data from oil test wells (Lozinsky, 1988, 1994; Connell, Koning, and Derrick, this volume; Connell et al., 1999; Tedford and Barghoorn, 1999; Maldonado et al., 1999; Black and Hiss, 1974). Locations of wells and stratigraphic sections on Figure 1. Units A and B are interpreted as pre-Piedra Parada Member deposits encountered in the Tamara well.

A-9 NMBMMR OFR 454B Tanos and Blackshare Formations strata are not considered part of the Zia Formation, primarily because the Tanos Formation contains a The Tanos and Blackshare formations are newly thick succession of mudstone and fluvial sandstone proposed names for well-cemented, moderately tilted interpreted to be deposited in a basin-floor, playa- conglomerate, sandstone, and mudstone of the lower lake/distal-piedmont setting. Santa Fe Group, exposed in the Hagan embayment The Tanos Formation is conformably overlain by (Connell and Cather, this volume). These informal a >700 m succession of sandstone and conglomerate units are unconformably overlain by the Tuerto informally called the Blackshare Formation, for the Formation. The Tanos Formation is a 253-m thick nearby Blackshare Ranch, which is in a tributary of succession of conglomerate, thinly to medium bedded Tanos Arroyo. The Blackshare Formation is a mudstone and tabular sandstone that rests succession of interbedded sandstone, conglomerate disconformably upon the Espinaso Formation. The and thin mudstone. Conglomerate beds are age of the base of the Tanos Formation is constrained commonly lenticular and sandstone intervals by an olivine basalt flow about 9 m above its base, commonly fine upward into thin mudstone beds that which yielded a 40Ar/39Ar date of 25.41±0.32 Ma are commonly scoured by overlying lenticular (Cather et al., 2000; Peters, 2001b), supporting an conglomerate. The upper boundary of the Tanos earlier K/Ar date of about 25.1±0.7 Ma (Kautz et al., Formation is gradational and interfingers with the 1981). Thus, the basal Santa Fe Group deposits at overlying Blackshare Formation. An ash within the Espinaso Ridge are slightly older than the basal Zia Blackshare Formation is projected to be ~670-710 m Formation exposed along the western margin of the above the base. This ash yields a 40Ar/39Ar date of Calabacillas sub-basin. Thus, the basal Santa Fe 11.65±0.38 Ma (Connell and Cather, this volume). Group deposits at Espinaso Ridge are slightly older Estimates of stratal accumulation rates (not adjusted than the basal Zia Formation exposed along the for compaction) for much of the Tanos-Blackshare western margin of the Calabacillas sub-basin. The succession, based on these two dates, is about 72 basal contact is sharp and scoured. A continuous dip- m/m.y.. meter log for a nearby oil-test well indicates the presence of an angular unconformity between the Zia Formation Tanos and Espinaso formations. The mapped extent of the Tanos Formation The Zia Formation ranges from 350 m to at least roughly coincides to strata tentatively correlated to 853 m in thickness and represents a predominantly the Abiquiu Formation by Stearns (1953) and to the eolian phase of lower Santa Fe Group deposition in Zia Formation by Kelley (1979). Stearns (1953) the Calabacillas sub-basin. It is exposed along the assigned these beds to the Abiquiu Formation, eastern margin of the Rio Puerco valley (Ceja del Rio principally because of the abundance of volcanic Puerco of Bryan and McCann, 1937, 1938) and along detritus in the section. Kelley (1977) correlated them the southwestern margin of the Rio Jemez valley to the Zia Formation, probably on the basis of (Rincones de Zia, Galusha, 1966; Tedford, 1981). stratigraphic position, light coloration and thick The southern limit of exposures of the Cerro Conejo tabular sandstone beds. Recent studies (Cather et al., Member are near Benavidez Ranch, about 15 km 2000; Large and Ingersoll, 1997) indicate that these west of Rio Rancho (Morgan and Williamson, 2000). deposits were locally derived by west-northwest- Bryan and McCann (1937) informally designated the flowing streams from the Ortiz Mountains, rather lowermost sediments as the “lower gray” member of than from the more rhyolitic Latir eruptive center to their Santa Fe formation. the north near Taos, New Mexico (Ingersoll et al., The Zia Formation is characterized by massive to 1990). Kelley (1977) interpreted these facies to be cross-stratified, weakly to moderately cemented, well related to the Zia Formation, however the lack of to moderately sorted arkose to feldspathic arenite large-scale crossbedding and presence of abundant with scattered thin to medium bedded muddy mudstone suggests basin-floor deposition in basin- sandstone and mudstone interbeds (Beckner, 1996; floor (playa-lake and mudflat) and piedmont-slope Connell et al., 1999; Tedford and Barghoorn, 1999). environments, rather than in an eolian dune field. Concretionary zones cemented with poikilotopic These deposits are also considerably less quartz-rich calcite crystals (Beckner and Mozley, 1998) are than those of the Zia Formation. common in the lower members, but decrease in The Tanos Formation is, in part, temporally abundance upsection (Connell et al., 1999). equivalent to the Abiquiu Formation, but are not Paleocurrent observations indicate wind from the included in the Abiquiu Formation because they west (Gawne, 1981). The Zia Formation is contain abundant locally derived volcanic grains and subdivided into four members, in ascending clasts that are derived from the adjacent Ortiz stratigraphic order: the Piedra Parada, Chamisa Mesa, Mountains (Large and Ingersoll, 1997), rather than Cañada Pilares, and Cerro Conejo members. The two from the Latir volcanic field (Smith, 1995; Moore, lowest members were defined by Galusha (1966). 2000; Large and Ingersoll, 1997). Tanos Formation Gawne (1981) defined the Cañada Pilares Member,

A-10 NMBMMR OFR 454B and Connell et al. (1999) proposed the Cerro Conejo Member to round out the Zia Formation stratigraphy.

Figure 8. Summary of development of stratigraphic nomenclature in the Santo Domingo sub-basin. Shaded units are volcanic; black shading indicates the basalts of Santa Ana Mesa and Cerros del Rio. Other sedimentary units include the gravel of Lookout Park Figure 7. Summary of stratigraphic nomenclature (GLP) of Smith and Kuhle (1998a, b). Volcanic units development in the northwestern Calabacillas sub- include the basalt of Chamisa Mesa (M), Canovas basin. Sedimentary units include the Cañada Pilares Canyon (CC) Formation, Paliza Canyon Formation Member (CPM) of the Zia Formation. Volcanic rocks (P), basalt at Chamisa Mesa (BCM), and Bearhead are shaded gray. Rhyolite (B). Volcanic rocks are shaded gray. Pliocene basaltic rocks are shaded black. The Piedra Parada Member is a 70-m thick eolianite succession resting upon a low relief Fossil mammals collected from the lower 20 m unconformity cut onto subjacent strata (Tedford and of the Piedra Parada type section and in Cañada Barghoorn, 1999). The basal contact contains a Pilares are latest Arikareean in age (19-22 Ma, nearly continuous lag of siliceous pebbles and small Tedford and Barghoorn, 1999). These fossils are cobbles derived from the subjacent Galisteo closely correlative to fossils of the “upper Harrison Formation and Oligocene volcanic rocks. These beds” of (MacFadden and Hunt, 1998), intermediate volcanic rocks have been shaped into which are about 19 Ma (R.H. Tedford, 2000, written ventifacts and locally lie on a calcic soil developed commun.). Magnetostratigraphic and biostratigraphic on older deposits (Tedford and Barghoorn, 1999). studies by Tedford and Barghoorn (1999) indicate Three volcanic cobbles at this contact were dated at that the Cañada Pilares and Cerro Conejo members 31.8±1.4 Ma, 33.03±0.22, and 33.24±0.24 Ma using accumulated at a rate of about 69-83 m/my. the 40Ar/39Ar technique on hornblende and biotite Extrapolation of this stratal accumulation rate to the (S.M. Cather and W.C. McIntosh, written commun., base of the Zia Formation support an age of about 19 2000). The Piedra Parada Member records deposition Ma for the base of the Piedra Parada Member (R.H. of an eolian dune field with ephemeral interdunal Tedford, 2000, written commun.). ponds and sparse, widely spaced fluvial channel The Piedra Parada Member grades upsection into deposits (Gawne, 1981). A basal pebbly sandstone the Chamisa Mesa Member (Galusha, 1966), which mostly composed of siliceous pebbles recycled from represents deposition of eolian sand sheets and a recycled Galisteo Formation and Mesozoic strata on slight increase in fluvial and local lacustrine the Colorado Plateau is present at Galusha’s (1966) deposition (Tedford and Barghoorn, 1999; Gawne, type Piedra Parada Member section. Paleocurrent 1981). Mammalian remains indicate deposition analyses of this discontinuous basal fluviatile interval during late-early Miocene time (early to late by Gawne (1981) indicate eastward paleoflow, Hemingfordian, 16-18 Ma; Tedford and Barghoorn, although there is considerable scatter in her data. 1997). These clasts could have been derived from the The Zia Formation was further sub-divided into Mogollon-Datil volcanic field to the south, the unit of the late Hemingfordian (16-18 Ma; Tedford and Isleta #2 to the southeast, Ortiz Mountains to the east, Barghoorn, 1999) Cañada Pilares Member (Gawne, or possibly from the San Juan volcanic field to the 1981), a 20- to 30-m thick succession of red and north; however, the proximity of these deposits to the green, fluviolacustrine claystone and limestone, and unit of Isleta #2 in drillholes to the south suggest a thinly bedded pink sandstone, and eolian sandstone probable derivation from the unit of Isleta #2. overlying the Chamisa Mesa Member (Tedford and Barghoorn, 1999; Gawne, 1981).

A-11 NMBMMR OFR 454B The Cerro Conejo Member is the highest Conejo Member occurred during part of middle to member of the Zia Formation. The Cerro Conejo late Miocene time (ca. 14-10 Ma). Member contains 300-320 m of very pale-brown to Magnetostratigraphic studies along the Ceja del pink and yellowish-red, tabular to cross-bedded, Rio Puerco indicate the presence of a 1-1.6 m.y. moderately to well sorted sand, with minor thinly hiatus in deposition near the boundary of the Cañada bedded mud, and rare very fine-grained pebbly sand. Pilares and Cerro Conejo members (Tedford and At the type section, the Cañada Pilares Member is Barghoorn, 1999). At the type section, the basal missing. The top of the Cerro Conejo is conformable contact with Chamisa Mesa Member sandstone is and Along the northern Ceja del Rio Puerco, near sharp. Estimates of stratal accumulation rates (not Navajo Draw, the contact between the Cerro Conejo adjusted for compaction) for the Piedra Parada-Cerro and Navajo Draw Members is sharp on the footwall Conejo succession is 79-83 m/m.y. (Tedford and of the San Ysidro fault. To the east, this contact is Barghoorn, 1999). gradational and both members interfinger (Connell et The stratigraphic assignment of this unit has al., 1999; Koning and Personius, in review). created debate based on the interpretation of The Cerro Conejo Member locally forms depositional environments (Connell et al., 1999; prominent ledges and cliffs and is slightly redder and Pazzaglia et al., 1999; Tedford and Barghoorn, 1999). more thickly bedded than the more topographically The Cerro Conejo Member, originally part of subdued Piedra Parada and Chamisa Mesa members. Galusha’s (1966) “ equivalent” At the type locality, over a quarter of the section unit, was assigned to an upper unnamed member of contains thickly bedded, cross stratified, fine- to the Zia Formation by Tedford and Barghoorn (1997). coarse-grained sand that locally exhibit multiple They subsequently included these deposits in the grain-fall and grain-flow laminations with local Arroyo Ojito Formation because of the greater reverse grading, indicating eolian deposition. Much proportion of fluvial sand and mud in the unit. of the section is a mixture of massive to cross-bedded The Cerro Conejo Member is interpreted here to sand with subordinate, thinly to medium bedded represent a transition between the lower, well sorted, sandy mud and mud. Mudstone beds and lenticular sandy, eolian-dominated deposits of the Piedra bedforms are more abundant in the overlying Arroyo Parada-Cañada Pilares succession, and the overlying, Ojito Formation. Gravelly sand beds are rare south of more poorly sorted, fluvially dominated units of the the Rio Jemez valley (Connell et al., 1999), but Arroyo Ojito Formation. Connell et al. (1999) placed contain a slightly greater abundance of pebbly sand the Cerro Conejo Member within the Zia Formation, north of the Rio Jemez (Chamberlin et al., 1999). based primarily on lithologic similarities to Biostratigraphic data indicate that the Cerro underlying members of the Zia Formation. In Conejo is late Barstovian to Clarendonian (14-8 Ma; contrast, Tedford and Barghoorn (1999) assigned the Tedford and Barghoorn, 1999; Connell et al., 1999; Cerro Conejo Member to the Arroyo Ojito Formation Morgan and Williamson, 2000), or middle to late on the basis of lithogenetic interpretations. A strictly Miocene, in age. The Rincon quarry of Galusha lithologic criterion for the placement of the Cerro (1966) contains fossils correlated to the late Conejo Member within the Zia Formation is Barstovian land-mammal “age,” which is about 12-14 preferred, primarily because of the sandy nature of Ma (Tedford and Barghoon, 1999). This quarry was the unit and lack of thickly bedded mudstone and re-located in the fall of 1999 and projected near the conglomeratic beds, which are more abundant in the base of the type section, and not within higher units, overlying fluvially dominated Arroyo Ojito as previously thought (see Connell et al., 1999). At Formation. Alternatively, the Cerro Conejo Member least five altered volcanic ashes are present in the may be lithologically distinct enough to assign as its middle of this unit. Tedford and Barghoorn (1997) own formation, which could indicate the transitional report a K/Ar date of 13.64±0.09 Ma on biotite from status of this unit between the lower and upper sub- a volcanic ash near Cañada Pilares along the Ceja del groups of the Santa Fe Group. The Cerro Conejo Rio Puerco. A stratigraphically higher ash-bearing should, however, not be included in the Arroyo Ojito sequence is present just east of the Ziana structure, Formation, because it is lithologically distinct from near US-550, where a 10.8-11.3 Ma tephras are the fluvially dominated deposits of the overlying tentatively correlated to the Trapper Creek sequence Arroyo Ojito Formation. in Idaho (Personius et al., 2000; Koning and The Zia Formation is partly equivalent in age to Personius, in review; Dunbar, 2001, oral commun., the Oligo-Miocene Abiquiu Formation, a Sarna-Wojciki, 2001, written commun.). The upper volcaniclastic sandstone and conglomerate derived part of the Cerro Conejo Member is interbedded with from the Latir volcanic field in northern New the 10.4 Ma basalt of Chamisa Mesa and is overlain Mexico. The Abiquiu Formation is exposed along the by 9.6 Ma flows of the Paliza Canyon Formation northwestern flank of the Jemez volcanic field and on (Chamberlin et al., 1999) along the southern flank of the crest of the northern Sierra Nacimiento (Smith et the Jemez Mountains. Thus, deposition of the Cerro al., 1970; Woodward, 1987; Woodward and Timmer, 1979). Petrographic studies (Beckner, 1996; Large

A-12 NMBMMR OFR 454B and Ingersoll, 1997) indicate that the Zia and Abiquiu Popotosa Formation Formations are petrographically dissimilar; however, definitive evidence regarding stratigraphic The Popotosa Formation comprises an >1860 m relationships between these units is not known. Zia succession of moderately to well cemented, and Formation sandstone is quartz-rich compared to the moderately tilted, conglomerate, mudstone, and Abiquiu Formation and was deposited by winds from sandstone exposed along the margins of the Belen the west-southwest, with widely scattered south- sub-basin. The Popotosa Formation was defined by southeast flowing streams (Gawne, 1981). Abiquiu Denny (1940), who considered it to be a pre-Santa Fe Formation sandstone contains abundant feldspar and Group deposit. Machette (1978a) later assigned it to lithic fragments and was deposited by southwest- the lower Santa Fe Group (Fig. 9). The Popotosa flowing streams that drained the Latir volcanic field Formation rests unconformably on the subjacent La (Smith, 1995; Moore, 2000). Sparse gravels in the Jara Peak basaltic andesite and Cerritos de las Minas Piedra Parada Member contain abundant rounded (Machette, 1978a; Osburn and Chapin, 1983) and is chert and quartzite with scattered intermediate unconformably overlain by fluvial and basin-margin volcanic rocks. The eastward transport direction of deposits of the upper Santa Fe Group (Sierra Zia Formation eolian sandstone suggests that this unit Ladrones Formation; Machette, 1978a). The could have been recycled from arkose and subarkose piedmont and fluviolacustrine members, or facies, of Mesozoic-Paleogene rocks exposed in the adjacent constitute the major facies of the Popotosa Colorado Plateau (Stone et al., 1983). Minor Formation. Bruning (1973) designated a reference recycling of Abiquiu Formation strata cannot be ruled section in Silver Creek, a tributary of the Rio Salado, out during Zia time. The presence of Pedernal chert, a where he described three dominant facies: a piedmont chalcedony and chert that comprises the middle facies; a fluviolacustrine facies; and the granite- member of the Abiquiu Formation (Moore, 2000; bearing fanglomerate of Ladron Peak (Bruning, 1973; Woodward, 1987), in the overlying Arroyo Ojito Chamberlin et al., 1982; Cather et al., 1994). The Formation, demonstrates recycling of Abiquiu piedmont facies contain 820-1860 m of sediments into the Albuquerque Basin during late predominantly volcanic-bearing conglomerate Miocene and Pliocene time. The presence of representing deposition of coarse-grained, stream- Pedernal Member clasts in the San Juan Basin (Love, and debris-flows deposits derived from adjacent 1997) and southeast paleoflow indicators in the footwall uplands along the basin margin (Bruning, Arroyo Ojito Formation, also suggest that the 1973; Lozinsky and Tedford, 1991). These deposits Abiquiu Formation probably extended west of the interfinger with fine-grained strata of the Sierra Nacimiento, and thus may have provided an fluviolacustrine facies, which are 240-1070 m in additional source of sediment into the Albuquerque exposed thickness (Bruning, 1973). The Basin. Additional study is needed to further constrain fluviolacustrine facies is the most distinctive and the lateral extent of the Abiquiu Formation in the San contains light-gray and light-grayish-green to Juan Basin. medium reddish-brown, poorly sorted, silty clay to An anomalously thick succession of lower Santa sand with sparse pebbly beds. This facies also Fe Group was recognized by Kelley (1977, p. 14) in contains primary (bedded) and secondary (fracture the Santa Fe Pacific #1 test well, which was spudded fill) gypsum and numerous middle-late Miocene ash in the Zia Formation (Black and Hiss, 1974), about beds (Cather et al., 1994; Bruning, 1973). This facies 10 km east of the Zia Formation type area. This well represents deposition in a very low-gradient playa encountered 853 m of Zia Formation strata above the lake or alluvial flat bounded by sandy, distal alluvial Galisteo Formation. This is much thicker than the fan deposits (Lozinsky and Tedford, 1991; Bruning, 350 m measured at the type localities (Connell et al., 1973). The fanglomerate of Ladron Peak is 150-915 1999) and indicates that the Zia Formation thickens m thick (Bruning, 1973), rests conformably on considerably, east of the type sections on Zia Pueblo. fluviolacustrine and piedmont facies, and is At least 762 m of Zia Formation sandstone was associated with the flanks of the Ladron Mountains recognized in the Davis Petroleum Tamara #1-Y well (Bruning, 1973; Chamberlin et al., 1982). The (Connell, Koning, and Derrick, this volume). Kelley Popotosa Formation typically dips more steeply (1977) speculated that the basal Zia Formation (about 15-35º; Cather et al., 1994) and is better exposed to the west might be younger than the basal cemented than the overlying deposits of the upper Zia Formation encountered in these wells. The Santa Fe Group. difference in thickness between these two wells and the absence of Oligocene strata under the Ziana structure and on the exposed contact with the Zia Formation to the west suggest that erosion of older strata occurred prior to about 19 Ma in the northwestern part of the Calabacillas sub-basin.

A-13 NMBMMR OFR 454B commun., 2000; Osburn and Chapin, 1983), which overlies playa lake sediments (Chamberlin, 1980), about 20 km west of Socorro, New Mexico. Late Miocene (Hemphillian and possible Clarendonian) mammal fossils are recognized in the upper part of the fluviolacustrine facies in the Gabaldon badlands in the western Belen sub-basin (Lozinsky and Tedford, 1991). Deposition of the Popotosa Formation began after about 25 Ma in the Abbe Springs basin, west of Socorro, and about 15 Ma in the Socorro area (Cather et al., 1994; Osburn and Chapin, 1983). Popotosa deposition probably ended between 5-7 Ma in the northern Socorro Basin, as constrained by dates from the Socorro area. The ancestral Rio Grande began to flow through the Socorro area and into the Engle and Palomas basins by 4.5-5 Ma (Mack et al., 1996, 1993; Leeder et al., 1996). The Popotosa Formation is temporally equivalent to the Hayner Ranch and Rincon Valley formations in the Palomas and Mesilla basins of southern New Mexico (Seager et al., 1971) and the Figure 9. Summary of stratigraphic nomenclature Tesuque Formation in the Española Basin (Spiegel development in the Belen sub-basin, illustrating the and Baldwin, 1963; Galusha and Blick, 1970). The evolution of stratigraphic terms in the northern Popotosa Formation is similar in age to the Zia Socorro Basin and Belen sub-basin. Formation and lower part of the Arroyo Ojito Formation. The northern extent of Popotosa- The age of the Popotosa Formation is equivalent fluviolacustrine mudstone extends north to constrained by biostratigraphic and radioisotopic near the Calabacillas-Belen sub-basin boundary data, mostly from the Socorro region. The Popotosa (Lozinsky, 1994). Estimates of stratal accumulation Formation rests unconformably on the 26.3±1.1 Ma (not adjusted for compaction) on the Popotosa andesite at Cerritos de las Minas (Bachman and Formation is about 600 m/m.y for the Gabaldon Mehnert, 1978; Machette, 1978a). The top of the badlands area (Lozinsky, 1994). Popotosa Formation is defined by a prominent angular unconformity along the western margin of Upper Santa Fe Group the Socorro Basin and Belen sub-basin. This unconformity probably becomes conformable near Deposits of the upper Santa Fe Group are areally basin depocenters (Cather et al., 1994). The base of extensive and typically bury deformed and better the Popotosa Formation is constrained by the cemented rocks of the lower Santa Fe Group. Upper 16.2±1.5 Ma Silver Creek andesite (Cather et al., sub-group sediments record fluvial deposition of 1994) in the Socorro area; however, the Popotosa is streams and rivers through externally drained basins as old as 25.9±1.2 Ma unit of Arroyo Montosa in the (Hawley, 1978). During this time, the Albuquerque Abbe Springs basin to the west (Osburn and Chapin, Basin was a large contributory basin (Lozinsky and 1983). The upper age of the Popotosa Formation is Hawley, 1991) where western margin tributaries constrained by a unit of the Socorro Peak Rhyolite merged with the ancestral Rio Grande axial-fluvial (rhyolite of Grefco quarry; Chamberlin, 1980, 1999), system near San Acacia, New Mexico. The ancestral about 6 km southwest of Socorro, which has been Rio Grande formed a narrow (axial) trunk river in the dated at 7.85±0.03 Ma (Newell, 1997, p. 13, 27). Socorro Basin. This trunk river flowed south, near This flow is interbedded with piedmont and Hatch, New Mexico, where it formed a broad fluvial fluviolacustrine facies (Chamberlin, 1999). The braid plain that was constructed during periodic piedmont facies at the Grefco locality contains avulsions into adjacent basins (Hawley et al., 1969, abundant reddish-brown sandstone clasts derived 1976; Mack et al., 1997; Lozinsky and Hawley, from the , exposed along the eastern 1991). margin of the Socorro Basin (Chamberlin, 2000, oral The upper Santa Fe Group can be divided into commun.), indicating that the fluviolacustrine facies three major lithofacies assemblages in the extended west of the Grefco locality by 7.9 Ma. The Albuquerque Basin, reflecting differences in deposit youngest constraint is from the 6.88±0.02 Ma texture, provenance, and paleoenvironment. These (McIntosh and Chamberlin, unpubl. 40Ar/39Ar date) lithofacies assemblages are referred to here as the trachyandesite of Sedillo Hill (Chamberlin, oral western-fluvial, axial-river, and piedmont lithofacies.

A-14 NMBMMR OFR 454B Western-fluvial deposits are predominantly nature of the western-fluvial deposits indicates extrabasinal and contain locally abundant red granite, compositional maturity of the sandstone fraction sandstone, and chert. These deposits were derived (Large and Ingersoll, 1997), and may indicate from large rivers and streams developed on the derivation from a stable source; probably Cretaceous western margin of the basin. Axial-river deposits sediments exposed on the adjacent Colorado Plateau refer to detritus laid down by the ancestral Rio (Gillentine, 1996). Grande. Composition of the fluvial facies is The Cochiti Formation interfingers with western predominantly extrabasinal and contains a mixed fluvial deposits, but is composed almost entirely of assemblage of clast types (Lozinsky et al., 1991). volcaniclastic sediments derived from the southern Piedmont facies are present along the flanks of the Jemez Mountains. basin, on the footwalls of major rift-margin uplifts, The Sierra Ladrones Formation is herein and contain locally derived detritus from nearby rift- restricted to fluvial deposits associated with the border drainages. ancestral Rio Grande fluvial system and Deposits of the upper Santa Fe Group typically interfingering footwall-derived piedmont deposits. have few concretionary or well cemented intervals, The Arroyo Ojito Formation is herein expanded to except locally along faults or near piedmont/axial- represent fluvial deposits derived from drainages of fluvial boundaries. Bedding is generally more the western margin. The Arroyo Ojito Formation lenticular than the tabular beds of the Zia Formation. represents the most areally extensive lithofacies of Poikilotopic calcite and concretionary sandstone, the upper Santa Fe Group and can be subdivided into common in the Zia Formation (Beckner and Mozley, at least three mappable members near the 1998), are rare in stratigraphically higher deposits. northwestern margin of the Calabacillas sub-basin Buried soils are also typically more common in the (Connell et al., 1999). upper Santa Fe Group, and locally can be quite Relatively thin, locally derived piedmont gravels common and widespread near the top of the section. are locally preserved on hanging wall hinges and Upper Santa Fe Group sediments are divided into the structural re-entrants in the basin. The Tuerto Sierra Ladrones Formation, Cochiti Formation, Formation is a volcanic-bearing gravel derived from Arroyo Ojito Formation, Tuerto Formation, the the Ortiz Mountains and is found in the Hagan gravel of Lookout Park, and a number of smaller embayment. Another such deposit is the gravel of local units exposed along the structural margins of Lookout Park (Smith and Kuhle, 1998a, b), which is the basin. derived from volcanic rocks of the southeastern flank Axial-fluvial and piedmont deposits comprise of the Jemez Mountains. the Sierra Ladrones Formation (Machette, 1978a), which has been extended throughout much of the Sierra Ladrones Formation Albuquerque Basin (Lucas et al., 1993; Cather et al., 1994; Smith and Kuhle, 1998a; Connell and Wells, The Sierra Ladrones Formation was defined by 1999). The axial-fluvial facies form a relatively Machette (1978a) for slightly deformed, coarse- narrow belt between the western fluvial and piedmont grained interfingering fluvial and basin-margin lithofacies. Piedmont deposits interfinger with piedmont deposits that unconformably overlie the western and axial-fluvial deposits near the basin Popotosa Formation in the northern Socorro Basin margins (Machette, 1978a; Connell and Wells, 1999; and Belen sub-basin. No type section was measured. Maldonado et al., 1999). A composite type area was proposed on the San The western-fluvial lithofacies contain Acacia quadrangle, which was designated as sandstone, conglomerate, and mudstone that were representative of western-margin piedmont, central deposited by streams draining the eastern Colorado axial-fluvial, and eastern-margin piedmont facies Plateau, southeastern San Juan Basin, and the Sierra tracts (Machette, 1978a); however, no stratigraphic Nacimiento. These western fluvial deposits comprise sections were described for this widely mapped unit the Arroyo Ojito Formation (Connell et al., 1999) and (Connell et al., 2001). The Sierra Ladrones stratigraphically similar facies to the south (Love and Formation was deposited by a through-flowing river Young, 1983; and Lozinsky and Tedford, 1991). This that marks the end of internal basin drainage lithofacies represents fluvial deposition of ancestral represented by the Popotosa Formation. Thickness of Rio Puerco, Rio Salado, Rio San Jose, and Rio the Sierra Ladrones Formation is greater than 470 m Guadalupe/Jemez fluvial systems. Western fluvial (estimate from cross section, Machette, 1978a) at its lithofacies interfinger with axial-fluvial deposits of type area, but is over 1 km thick beneath the ancestral Rio Grande near the present Rio Grande Albuquerque (Connell et al., 1998a; Hawley, 1996). Valley (Lozinsky et al., 1991). Fluvial deposits are typically light-gray to light Western-fluvial lithofacies generally contain yellowish-brown, non-cemented to locally cemented, greater amounts of quartz than in the axial-fluvial moderately sorted, trough cross stratified sand and lithofacies, which is commonly contains more gravel with rare muddy interbeds that are commonly volcanic detritus (Gillentine, 1996). The quartzose found as rip-up clasts and mud balls. Sandy and

A-15 NMBMMR OFR 454B gravelly deposits typically form multilateral (1978a) eastern-margin piedmont deposit may be part channels. The lack of preservation of mud suggests of the western-fluvial systems tract and should be deposition by anastomosing or braided rivers. reassigned to the Arroyo Ojito Formation. Piedmont deposits of the Sierra Ladrones Formation Lozinsky and Tedford (1991) extended the Sierra are typically better cemented and more poorly sorted Ladrones Formation northward into the Gabaldon than fluvial deposits. Piedmont deposits are typically badlands. They recognized that these deposits are light-brown to reddish-brown in color and tend to related to fluvial systems that originated along the form a rather narrow belt against footwall uplands; western margin of the basin, rather than from an however, the uppermost part of the piedmont facies ancestral Rio Grande. Paleocurrent measurements prograded basinward by 5-10 km (up to 20 km west and gravel composition indicates that these deposits of the Manzano Mountains) during early Pleistocene contain were derived from the western margin of the time. Conglomeratic beds of the axial-fluvial basin (Lozinsky and Tedford, 1991). Thus, these lithofacies typically consist of well sorted, well deposits are assigned to the Arroyo Ojito Formation. rounded quartzite with subordinate, subrounded to The Sierra Ladrones Formation is broadly subangular volcanic, hypabyssal intrusive, granite, equivalent to the Plio-Pleistocene Camp Rice and chert, and basalt. The Pedernal chert, a locally Palomas formations (Gile et al., 1981; Lozinsky and common constituent of the Arroyo Ojito Formation, Hawley, 1986), which record deposition of an is quite rare (<1%) and is typically better rounded ancestral Rio Grande beginning by around 4.5-5 Ma than in the Arroyo Ojito Formation. Piedmont (Mack et al., 1993, 1996; Leeder et al., 1996). The lithofacies typically contain variable amounts of earliest definitive evidence for an ancestral axial river subangular to subrounded granite, limestone, the southern part of the basin is the presence of sandstone, and metamorphic rocks derived from southward-directed cross-bedded fluvial sandstone basin-margin drainages. underlying the 3.73±0.1 Ma basalt of Socorro Previous workers (Debrine et al., 1966; Evans, Canyon, just south of Socorro, New Mexico. (R.M. 1966) mapped an axial-fluvial facies of the ancestral Chamberlin and W.C. McIntosh, written commun., Rio Grande near Socorro, New Mexico. They traced 2000). The Pliocene trachyandesite at San Acacia it along the eastern margin of the Rio Grande valley overlies piedmont deposits derived from the eastern to just east of San Acacia, New Mexico. A narrow, basin margin (Machette, 1978a). This flow yielded a south-trending belt of axial-fluvial deposits were K/Ar date of 4.5±0.1 (Bachman and Mehnert, 1978), delineated just east of San Acacia (Cather, 1996). but has been dated at 4.87±0.04 Ma using the These fluvial deposits can be traced into Arroyo de la 40Ar/39Ar method (R.M. Chamberlin and W.C. Parida, about 8 km northeast of Socorro, where a McIntosh, 2000, oral communication). The presence medial Blancan (2.7-3.7 Ma; Morgan et al., 2000) of these basin-margin deposits only constrains the fossil assemblage is recognized in an exposed fluvial location, but not age of an ancestral axial river at the succession originally assigned to the Palomas boundary of the Socorro and Albuquerque basins. Formation (Palomas gravels of Gordon, 1910). Piedmont deposits beneath the San Acacia flow Machette (1978) mapped a nearly continuous, south- contain abundant granite clasts with lesser amounts trending belt of axial-fluvial deposits west of San of volcanic and sedimentary detritus. The Acacia and on the footwall of the Loma Blanca fault, composition of piedmont deposits underlying this along the western margin of the Belen sub-basin. early Pliocene flow is contrast to the volcanic- Interfingering piedmont deposits were assigned to the dominated conglomerate of the Popotosa Formation Sierra Ladrones Formation by Machette (1978a), who mapped to the east (Cather, 1996). The presence of considered these to be derived from the eastern and granite and sedimentary detritus supports Machette’s western margins of the basin. The presence of basin- (1978a) assignment of these deposits to the Sierra margin, piedmont-slope facies between two “axial- Ladrones Formation, which locally constrains the age fluvial” facies indicates: 1) fluvial deposits are of of the unconformity between the Sierra Ladrones and different ages; 2) Machette’s (1978) eastern-margin Popotosa formations to being older than 4.9 Ma near piedmont facies (unit Tsp of Machette, 1978a) has a San Acacia. Cross-bedded fluvial sand is present near different origin; or 3) axial-fluvial deposits exposed Arroyo de la Parida, which contain fossils that are near the western border was a large western-margin indicative a medial Blancan age of about 3.6-2.7 Ma tributary to the Rio Grande. Paleocurrent for the upper exposed part of the fluvial section there observations and gravel composition determined (Morgan et al., 2000). from exposures just north of the Rio Salado and Rio Precise estimates of the age of the Sierra Grande confluence indicate southeast-directed flow Ladrones Formation in the Belen sub-basin are (Connell et al., 2001) from a volcanic-rich source problematic, principally because of the area, such as the ancestral Rio Salado, which unconformable relationships with the youngest originates in volcanic rocks of the Bear Mountains. Popotosa Formation playa-lake beds at about 7-8 Ma. Gravel composition and paleocurrent observations The oldest Sierra Ladrones piedmont deposits are indicate a western source and suggest that Machette’s older than about 4.87 Ma. Ancestral Rio Grande

A-16 NMBMMR OFR 454B deposits are older than about 3.7 Ma and reports of subangular to angular blocks in gravelly beds of the axial-fluvial deposits entering southern New Mexico upper part of the Arroyo Ojito Formation. The between 4.5-5 Ma suggest that the ancestral Rio Pedernal chert is rarely found in ancestral Rio Grande Grande was flowing through the Socorro area by 4.5- sediments, where it is better rounded than in the 5 Ma. Thus, deposition of the Sierra Ladrones Arroyo Ojito Formation. Formation probably began sometime between 7-4.5 The Arroyo Ojito Formation is 437 m thick at Ma. the type section, where it is subdivided into three The age of the uppermost Sierra Ladrones members (Connell et al., 1999). The Navajo Draw Formation is constrained by fallout ash from the Member is the lowest unit of the Arroyo Ojito upper Bandelier Tuff (Tshirege Member), and Formation and overlies the Cerro Conejo Member of fluvially transported clasts of the lower Bandelier the Zia Formation with a fairly sharp and contact Tuff (Connell et al., 1995; Connell and Wells, 1999), along the Ceja del Rio Puerco (Fig. 1). This contact, early Irvingtonian (ca. 1.6-1.2 Ma) fossils (Lucas et however, is gradational and interfingers with the Zia al., 1993), and fallout ash from the 0.6-0.66 Ma Lava Formation to the east (Koning and Personius, in Creek B ash within inset fluvial and piedmont review; Connell et al., 1999). deposits in the Santo Domingo sub-basin (Smith and The Navajo Draw Member is about 230 m in Kuhle, 1998b) and Calabacillas sub-basin (N. thickness and overlies the Cerro Conejo Member. Dunbar, 2000, oral commun.). Thus, Sierra Ladrones The Navajo Draw Member marks a significant Formation deposition ended between 1.3-0.6 Ma in change from the mixed eolian and sand-dominated the Albuquerque Basin. In the Socorro Basin, fluvial system of the Zia Formation to a more mud- entrenchment of the ancestral Rio Grande began after gravel dominated fluvial deposition of the Arroyo emplacement of pumice flood deposits and fallout of Ojito Formation. This lower member is a very pale- the Bandelier Tuff events (Cather, 1988), which is brown to pale-yellow, lenticular, poorly to now considered part of the upper Santa Fe Group moderately sorted, fine- to coarse-grained sand and basin-fill succession (S.M. Cather, oral commun., pebbly sand with minor thin to medium bedded pale- 2000). yellow mud. Gravelly beds are commonly clast supported and contain volcanic (mostly intermediate Arroyo Ojito Formation composition) pebbles and subordinate sandstone and brownish-yellow fine chert pebbles, and rare red The Arroyo Ojito Formation (Connell et al., granite and Pedernal chert clasts derived from 1999) was proposed for fluvial sediments along the southeast-flowing streams (Connell et al., 1999). The western margin of the Albuquerque Basin that were Navajo Draw Member is conformably overlain by the derived from the eastern Colorado Plateau, Sierra Loma Barbon Member of the Arroyo Ojito Nacimiento, and southern Jemez Mountains. The Formation, which contains fall-out lapilli and ash Arroyo Ojito Formation contains a rather diverse from the Peralta Tuff (6.8-7.3; Connell et al., 1999; assemblage of volcanic, sedimentary, and plutonic Koning and Personius, in review). clasts that can be differentiated from relatively The Loma Barbon Member is the middle unit of monolithologic (i.e., volcanic) Cochiti Formation of the Arroyo Ojito Formation and contains about 200 Smith and Lavine (1996). The Arroyo Ojito m of reddish-yellow to strong-brown and yellowish- Formation supercedes Manley’s (1978) Cochiti brown, poorly sorted, sand, pebbly sand, and gravel Formation (Connell et al., 1999). Conglomeratic parts at its type area. The Loma Barbon Member contains of the Arroyo Ojito Formation commonly contain locally abundant subangular to subrounded pebbles angular to subrounded red granite, basalt, sandstone, and cobbles of red granite that is probably derived conglomerate, and angular to subangular cobbles of from the Sierra Nacimiento. Clast composition the Pedernal chert, and thus differ from the redefined becomes increasingly heterolithic up section. volcaniclastic Cochiti Formation of Smith and Lavine Pedernal chert clasts also increase in abundance (1996). Gravelly beds of the Arroyo Ojito Formation, (Connell et al., 1999). The Loma Barbon Member is especially the Ceja Member, are distinctive because redder than the underlying Navajo Draw Member. they contain locally abundant subangular red granite This dominantly reddish-brown color may be the and Pedernal chert cobbles. Gravel beds are also result of recycling of sandstone and mudstone of the poorly sorted and have a bimodal distribution of Permo-Triassic section exposed along the flanks of gravel, typically containing abundant pebbles and Sierra Nacimiento (Woodward, 1987). A number of small cobbles with about 10-25% of scattered large fallout tephra correlative to the Peralta Tuff Member cobbles and small boulders. The Pedernal chert of (6.8-7.3 Ma, Connell et al., 1999; Koning and Church and Hack (1939) is a black and white Personius, in review) are present near the middle of chalcedony and chert of the middle member of the the unit. Rhyodacitic clasts in gravel beds having Abiquiu Formation (Moore, 2000). The Pedernal southeasterly paleoflow directions yielded dates of chert is exposed at the northern end of the Sierra 40Ar/39Ar dates of 3.79-4.59 Ma (Connell, 1998), Nacimiento (Woodward, 1987). It commonly forms suggesting derivation from the Tschioma Formation

A-17 NMBMMR OFR 454B (Polvadera Group). Soister (1952) recognized similar Morgan and Lucas, 1999, 2000; Wright, 1946). The deposits beneath 2.5±0.3 Ma (Bachman and Mehnert, Ceja Member is interbedded with 3.00±0.01 and 1978) basalt flows of Santa Ana Mesa. These 4.01±0.16 Ma basalt flows (Maldonado et al., 1999). deposits are likely correlative to the Loma Barbon In the Belen sub-basin, fluvially transported Member. Axial-fluvial deposits of the uppermost bivalves (Pycnodonte and/or Exogyra) from the Sierra Ladrones Formation overlie the Loma Barbon Cretaceous Dakota Formation-Mancos Shale Member and similar deposits (Cather and Connell, (Greenhorn Limestone) interval are found beneath 1998; Connell, 1998). Field relationships suggest that the Llano de Albuquerque, south of Los Lunas the Ceja Member pinches out to the east into the present (S.G. Lucas, written commun., 1999). Loma Barbon Member near Rio Rancho and Western fluvial deposits exposed beneath the Bernalillo, New Mexico. (Connell et al., 1998; southern end of the Llano de Albuquerque also Personius et al., 2000). contain recycled rounded obsidian clasts that were The Ceja Member (Kelley, 1977) is the derived from the 2.8-3.3 Ma East Grants Ridge uppermost member of the Arroyo Ojito Formation obsidian (Love and Young, 1983). Love and Young (Connell et al., 1999). Kelley (1977) applied the term (1983) and Wright (1946) also discuss deposition by Ceja Member to Lambert’s (1968, p. 271-274) upper large streams draining the western margin of the buff member type section at El Rincon in an attempt basin. to replace the uppermost part of the upper buff Near the southern end of the Belen sub-basin, member of Bryan and McCann (1937) and Wright Denny (1940) and Morgan and Lucas (2000) reported (1946). Later workers (Tedford, 1982; Lucas et al., Blancan fossils in Machette’s (1978b) eastern margin 1993) restricted the Ceja Member to upper Santa Fe piedmont deposits, exposed west of the Rio Grande Group sediments derived from the western basin valley and just north of the confluence with the Rio margin. The Ceja Member is 64 m at the type section Salado (Fig. 1., lj). at El Rincon (Kelley, 1977) where is forms an areally extensive pebble to small boulder conglomerate and Cochiti Formation conglomeratic sandstone beneath the Llano de Albuquerque. The Cochiti Formation was originally mapped The Ceja Member is poorly sorted and has a and defined (Bailey et al., 1969; Smith et al., 1970) bimodal gravel distribution with abundant pebbles for a succession of volcanic gravel and sand derived and scattered cobbles and boulders. The Ceja from erosion of the Keres Group in the southern Member unconformably overlies the Navajo Draw Jemez Mountains. The application of this term to Member on the footwall of the San Ysidro fault, but subsequent geologic and stratigraphic studies has appears to conformable to the south and east. Streams created varied and contradictory interpretations (cf. of the Ceja Member were part of Bryan and Manley, 1978; Smith and Lavine, 1996; Goff et al., McCann’s (1937, 1938) Rio Chacra fluvial system, a 1990; Chamberlin et al., 1999). These wide-ranging progenitor to the Rio Puerco. Conglomeratic deposits interpretations principally arise from complications in contain rounded sandstone and sparse quartzite- reconciling the volcanic stratigraphy of the Jemez bearing conglomerate that were probably recycled Mountains with the basin-fill stratigraphy of the from older Santa Fe Group and Galisteo Formation Santa Fe Group (Smith and Lavine, 1996). The exposed along the basin margin. The Ceja Member Cochiti Formation was redefined to include grades finer and thinner to the south and east, (see sedimentary strata of entirely volcanic composition Maldonado et al., 1999), but retains its bimodal that overlie Keres Group volcanic rocks and their cobbly to bouldery character. This southward correlative sedimentary strata south of the Jemez thinning and slight fining suggests that the Ceja Mountains (Smith and Lavine, 1996). Deposition of Member may pinch out to the south-southeast, near the Cochiti Formation is partly time equivalent to the Belen and Los Lunas; however a gravel commonly upper Arroyo Ojito Formation (Loma Barbon and underlies the Llano de Albuquerque. Cobbles of Ceja members) and can be differentiated by the Pedernal chert are locally common in this member. relative abundance of nonvolcanic clast constituents. Paleocurrent observations indicate deposition by The Cochiti Formation is very thin northwest of southeast-flowing streams, suggesting that the source Santa Ana Mesa (Chamberlin et al., 1999), but of recycled Pedernal chert was from the Colorado thickens to about 600 m along the southeastern flank Plateau, San Juan Basin, and western side of the of the Jemez Mountains, in Peralta Canyon (Smith Sierra Nacimiento. The presence of Pedernal chert and Kuhle, 1998a, b). (Abiquiu Formation) west of the Sierra Nacimiento is The age of the Cochiti Formation is constrained supported by the presence of Pedernal chert clasts in by the a 6.75 Ma pyroclastic bed of the Peralta Tuff, the southern San Juan Basin (Love, 1997); however, which underlies the base at Tent Rocks, in Peralta Miocene recycling of the Pedernal chert could have Canyon, (Smith and Kuhle, 1998c; Smith et al., also occurred. The Ceja Member and similar deposits 2001). The upper Cochiti Formation interfingers with contain Blancan vertebrate fossils (Lucas et al., 1993; upper Pliocene basalts of Santa Ana Mesa and the

A-18 NMBMMR OFR 454B lower Bandelier Tuff (Smith et al., 2001). The Plio- inset against upper Pliocene basalts of Santa Ana Pleistocene gravel of Lookout Park insets the Cochiti Mesa, and is unconformably overlain by the lower Formation. The Cochiti Formation records deposition member of the Bandelier Tuff. Thus, the gravel of of volcanic-bearing stream and piedmont sediments Lookout Park was deposited between about 2.4-1.6 from about 6.8 to 1.6 Ma. Ma.

Plio-Pleistocene basin-margin deposits Post-Santa Fe Group Deposits

A number of relatively thin conglomeratic and The upper boundary of the Santa Fe Group of gravelly deposits are recognized along the faulted Spiegel and Baldwin (1963, p. 39) is “considered to borders of the basin. These deposits commonly have include all but the terrace alluvium of present strongly developed petrocalcic soils with Stage III to valleys.” Most workers agree that the end of Santa Fe V carbonate morphology and are preserved on the Group deposition occurred when the ancestral Rio footwalls of basin margin or major intrabasinal faults Grande and major tributaries began to incise into near basin margins (Connell and Wells, 1999; older basin fill (Hawley et al., 1969; Gile et al., 1981; Maldonado et al., 1999). Wells et al., 1987). This definition is allostratigraphic The Tuerto Formation (gravel) was informally in nature and has no strong lithologic basis, making it named for a 20-30 m thick, subhorizontal deposit of difficult to apply in the basin (Connell et al., 2000). volcanic- and subvolcanic-bearing conglomerate and Delineation of strata that post-date Santa Fe Group sandstone unconformably resting on slightly to aggradation is ambiguous in such deposits because of moderately tilted older Santa Fe Group deposits lithological similarities to the underlying Santa Fe (Stearns, 1953). The Tuerto Formation can easily be Group. Post-Santa Fe Group valley floor and differentiated from underlying Santa Fe Group piedmont deposits commonly form stepped valley deposits by an abundance (about 10-25%) of green, border landforms inset against the Santa Fe Group. black, and yellow hornfels (Cather et al., 2000), These deposits were laid down during periods of which are interpreted as thermally metamorphosed aggradation that were punctuated by climate-driven Mesozoic and Paleogene strata exposed along the episodes of entrenchment by the ancestral Rio flanks of the Ortiz Mountains (S. Maynard, 2000, Grande and major tributaries (Hawley, 1978; Gile et oral commun.). The Tuerto Formation contain rare al., 1981; Wells et al., 1987). Differentiation of post- fine pebbles of granite, and are thus easily Santa Fe Group deposits is thus locally ambiguous differentiated from the granite-bearing Ancha because the size and character of drainage basins Formation (Spiegel and Baldwin, 1963). The basalts influence entrenchment. This geomorphic- of Cerros del Rio (mostly emplaced between 2.5-2.8 stratigraphic ambiguity is best expressed along the Ma; Woldegabriel et al., 1996; Bachman and Manzano and Manzanita Mountains where low-order Mehnert, 1978) interfinger with the lower part of the mountain-front drainages are not commonly graded Tuerto Formation (Stearns, 1979). The upper to entrenched surfaces associated with the Rio boundary is constrained by correlation of the upper Grande fluvial system. Unlike the larger drainages of constructional surface (Ortiz surface of Stearns, Tijeras Arroyo, Hell Canyon Wash, and Abo Arroyo, 1953) to the Plains surface formed on the Ancha streams on the western flank of the Manzanita and Formation near Santa Fe (Spiegel and Baldwin, Manzano Mountains commonly terminate on the 1963). The top of the is constrained Llano de Manzano of Machette (1985), a broad by primary fallout ash and lapilli correlated to one of abandoned basin-floor and piedmont slope east of the the Cerro Toledo Rhyolite tephras (ca. 1.48 Ma) and Rio Grande Valley. The Llano de Manzano forms a the presence of an ash correlated to the upper weakly dissected landscape (Pazzaglia and Wells, Bandelier Tuff. This ash is in deposits that are 1990; Connell and Wells, 1999) that makes interpreted to be inset against the Ancha Formation differentiation of post-Santa Fe Group deposits (Koning and Hallett, 2000). Based on correlations to difficult. The interaction of intrabasinal faults and the Ancha Formation, the Tuerto Formation was competence of tributary streams both likely play a deposited prior to 2.6 Ma. Deposition probably local role in defining when Santa Fe Group ceased between 1.2-1.5 Ma, however, the presence of deposition ceased (Connell et al., 2000). weakly to moderately developed calcic soils (Stage II Entrenchment of the Santa Fe Group would to III carbonate morphology) in the Tuerto Formation result in a steady decline in groundwater levels as the in the Hagan embayment, suggests that deposition of Rio Grande and its major tributaries incise into the the Tuerto Formation may have continued into the basin fill. Thus, deposits representing widespread middle Pleistocene. basin aggradation should be relatively poorly drained The gravel of Lookout Park is an informal unit with respect to their entrenched and better-drained recognized along the southeastern flank of the Jemez counterparts. Such relationships are recognized in Mountains (Smith and Kuhle, 1998a, b). This gravel Hell Canyon Wash, where early Pleistocene pumice- unconformably overlies the Cochiti Formation, is bearing deposits of the ancestral Rio Grande are well

A-19 NMBMMR OFR 454B cemented with sparry calcite, suggesting deposition Group succession is interbedded with basalts of Santa during high groundwater. Incised deposits, however, Ana Mesa and a 1.57 Ma ash correlated to the Cerro are not well cemented and contain disseminated or Toledo Rhyolite (N. Dunbar, 2001, written commun; micritic calcium-carbonate cements. Cather and Connell, 1998). Pliocene-Pleistocene tectonic activity is At Tijeras Arroyo, biostratigraphic data suggest recognized by the deposition of syntectonic the presence of a disconformity in the section depositional wedges (Smythe and Connell, 1999; between the Arroyo Ojito Formation and overlying colluvial wedges of Machette, 1978b) along the Bandelier-pumice-bearing fluvial deposits of the hanging walls of major intrabasinal normal faults. Sierra Ladrones Formation (Connell et al., 2000; Delineation of a single regionally correlative Lucas et al., 1993). Biostratigraphic data (Morgan surface of aggradation that marks the end of Santa Fe and Lucas, 1999, 2000) indicate a lack of late Group deposition is problematic and should be Blancan fossils (i.e., lack of fossils recording the abandoned in favor of a definition that allows for the Great American Interchange) in the Albuquerque development of multiple local tops that are Basin and suggest a hiatus in deposition occurred diachronous. Studies of White Rock Canyon at the during late Blancan time. The Llano de Albuquerque northern end of the Santo Domingo sub-basin is older than 1.2 Ma (Connell et al., 2000) and indicate that the Rio Grande excavated very deep perhaps is late Pliocene in age. The probable Pliocene valleys into basalt of the upper Pliocene Cerros del age of the areally extensive Llano de Albuquerque Rio volcanic field (Reneau and Dethier, 1996). The west of the Rio Grande and burial by Pleistocene Bandelier Tuff locally buried these deep valleys. deposits of the ancestral Rio Grande to the east may Much of the basalt exposed along White Rock account for the apparent lack of late Blancan fossils, Canyon were deposited in a short time mostly which could be buried by the younger Bandelier- between 2.8-2.3 Ma: Woldegabriel et al., 1996), pumice bearing deposits of the ancestral Rio Grande. resulting in the development of a constructional lava Another possible explanation for the lack of pile near the La Bajada and Pajarito faults. Evidence representative late Blancan fossils may be due to a for a regional late Pliocene unconformity in the reduction in sedimentation rate or hiatus in Española Basin in White Rock Canyon is clear; deposition. The disconformity at Tijeras Arroyo may however, incision of the Rio Grande into these basalt be due to earlier entrenchment of the ancestral Rio flows (Dethier, 1999) might be a local effect caused Puerco fluvial system along the western margin of by the river’s effort to maintain a graded profile the basin. With cessation of Arroyo Ojito deposition through White Rock Canyon, rather than the result of along the eastern part of the basin, local some regional unconformity. unconformities would develop between the A number of early Pleistocene constructional abandoned basin floor constructional surface of the surfaces that locally mark the top of the Santa Fe Llano de Albuquerque, and continued deposition of Group are recognized south of White Rock Canyon. the Sierra Ladrones Formation into the early The early Pleistocene Sunport and Llano de Pleistocene. The upper boundary of the Santa Fe Albuquerque surfaces (Albuquerque Basin), the Las Group thus is time transgressive and sensitive to the Cañas surface (Socorro Basin), and the lower La competence of streams, availability of sediments, and Mesa surfaces (Mesilla Basin) are rather broad the activity of faults (Connell et al., 2000). constructional surfaces that have clearly been entrenched by younger fluvial deposits associated ACKNOWLEDGMENTS with development of the Rio Grande valley. Magnetostratigraphic studies of the Camp Rice This study was supported by the New Mexico Formation in southern New Mexico, a correlative of Bureau of Mines and Mineral Resources. Much of the the Sierra Ladrones Formation, indicates that data discussed for this study came from numerous widespread basin-fill deposition was mostly open-file reports released by the New Mexico Bureau uninterrupted during Pliocene and early Pleistocene of Mines and Mineral Resources during the course of times (Mack et al., 1993). cooperative geologic mapping with the U.S. West of the Rio Grande, in the Santo Domingo Geological Survey (New Mexico Statemap Project). sub-basin, the Bandelier Tuff rests disconformably on The author is particularly grateful to the Pueblos of the gravel of Lookout Park, which sits with angular Zia, Isleta, Sandia, San Felipe, Santo Domingo, unconformity on the Sierra Ladrones and Cochiti Jemez, and Santa Ana for granting access during formations. Down dip and to the east, the Bandelier many of the stratigraphic and mapping studies Tuff and a Pliocene basalt flow are part of a referred to in this paper. In particular, the author conformable Santa Fe Group succession on the thanks Mr. Peter Pino for enabling access to study the eastern side of the Rio Grande (Smith et al., 2001; geologically important localities along the Rincones Smith and Kuhle, 1998c). Similar stratigraphic de Zia, Mr. Michael Romero for facilitating access to relationships are also recognized near San Felipe San Felipe Pueblo lands, and Mr. Archie Chavez for Pueblo, where a similarly aged conformable Santa Fe access to Sandia Pueblo lands. Mr. Blane Sanchez

A-20 NMBMMR OFR 454B and John Sorrell were particularly helpful in Santa Fe Pacific No. 1 test well, southern facilitating access and aiding research on Isleta Sandoval County, New Mexico: New Mexico Pueblo lands. This paper benefited greatly from the Geological Society, Guidebook 25, p. 365-370. New Mexico Geochronological Research Laboratory. Bruning, J.E., 1973, Origin of the Popotosa I thank Richard Chamberlin, Steve Cather, Dave Formation, nor-central Socorro County, New Love, Gary Smith, and John Hawley for reviewing an Mexico Bureau of Mines and Mineral Resources, earlier draft of this manuscript. I also thank Bill Open-file report 38, 132 p., 9 pl. McIntosh, Steve Cather, Dave Love, and Richard Bryan, K., and McCann, F.T., 1937, The Ceja del Rio Chamberlin for graciously allowing me to report Puerco-a border feature of the Basin and Range some of their unpublished 40Ar/39Ar dates. province in New Mexico, part I, stratigraphy and structure: Journal of Geology, v. 45, p. 801-828. REFERENCES AND PARTIAL Bryan, K., and McCann, F.T., 1938, The Ceja del Rio BIBLIOGRAPHY Puerco-a border feature of the Basin and Range province in New Mexico, part II, Abbott, J. C., Cather, S. M., and Goodwin, L. B., geomorphology: Journal of Geology, v. 45, p. 1- 1995, Paleogene synorogenic sedimentation in 16. the Galisteo basin related to the Tijeras- Cather, S.M., 1988, Geologic map of the San Antonio Cañoncito fault system: New Mexico Geological pumice deposit (SE/sec. 27 and NE/sec. 34, T4S, Society, Guidebook 46, p. 271-278. R1E), Socorro County, New Mexico: New Aldrich, M.J., Jr., Chapin, C.E., and Laughlin, A.W., Mexico Bureau of Mines and Mineral Resources, 1986, Stress history and tectonic development of Open-file report 343, 5 p., 1 pl. the Rio Grande rift, New Mexico: Journal of Cather, S.M., 1996, Geologic maps of upper Geophysical Research, v. 94, p. 6199-6244. Cenozoic deposits of the Loma de las Cañas, and Bachman, G.O., and Mehnert, H.H., 1978, New K-Ar Mesa del Yeso 7.5 minute quadrangles, New dates and the late Pliocene to Holocene Mexico: New Mexico Bureau of Mines and geomorphic history of the central Rio Grande Mineral Resources, Open-file report 417, 32 p., 2 region, New Mexico: Geological Society of pl., scale 1:24,000. America Bulletin, v. 89, p. 283-292. Cather, S.M., Connell, S.D., 1998, Geology of the Bailey, R.A., Smith, R.L., and Ross, C.S., 1969, San Felipe Pueblo 7.5-minute quadrangle, Stratigraphic nomenclature of volcanic rocks in Sandoval County, New Mexico: New Mexico the Jemez Mountains: U.S. Geological Survey Bureau of Mines and Mineral Resources, Open- Bulletin 1274-P, 19 p. File Digital Map 19, scale 1:24,000. Baldridge, W.S., Damon, P.E., Shafiqullah, M., and Cather, S.M., Chamberlin, R.M., Chapin, C.E., and Bridwell, R.J., 1980, Evolution of the central Rio McIntosh, W.C., 1994, Stratigraphic Grande rift, New Mexico: New Potassium-argon consequences of episodic extension in the ages: Earth and Planetary Sciences Letters, v. 51, Lemitar Mountains, central Rio Grande rift: n. 2, p. 309-321. Geological Society of America, Special Paper Baldridge, W.S., Perry, F.V., and Shafiqullah, M., 291, p. 157-170. 1987, Late Cenozoic volcanism of the Cather, S.M., Connell, S.D., and Black, B.A., 2000, southeastern Colorado Plateau: I. Volcanic Preliminary geologic map of the San Felipe geology of the Lucero area, New Mexico: Pueblo NE 7.5-minute quadrangle, Sandoval Geological Society of America Bulletin, v. 99, n. County, New Mexico: New Mexico Bureau of 10, p. 463-470, 1 pl. Mines and Mineral Resources, Open-file Digital Beckner, J.R., 1996, Cementation processes and sand Map DM-37, scale 1:24,000. petrography of the Zia Formation, Albuquerque Chamberlin, R.M., 1980, Cenozoic stratigraphy and Basin, New Mexico [M.S. Thesis]: Socorro, New structure of the Socorro Peak volcanic center, Mexico Institute of Mining and Technology, 146 central New Mexico: New Mexico Bureau of p. Mines and Mineral Resources, Open-file report Beckner, J.R, and Mozley, P.S., 1998, Origin and 118, 532 p., 3 pl. spatial distribution of early vadose and phreatic Chamberlin, R.M., 1999, Preliminary geologic map calcite cements in the Zia Formation, of the Socorro quadrangle, Socorro County, New Albuquerque Basin, New Mexico, USA: Special Mexico: New Mexico Bureau of Mines and Publications of the International Association of Mineral Resources, Open-file digital map 34, Sedimentology, v. 26, p. 27-51. scale 1:24,000. Birch, F.S., 1982, Gravity models of the Albuquerque Chamberlin, R.M., Logsdon, M.J., Eveleth, R.W., Basin, Rio Grande rift, New Mexico: Bieberman, R.A.., Roybal, G.H., Osburn, J.C., Geophysics, v. 47, n. 8, p. 1185-1197. North, R.M., McLemore, V.T., and Weber, R.H., Black, B.A., and Hiss, W.L., 1974, Structure and 1982, Preliminary evaluation of the mineral stratigraphy in the vicinity of the Shell Oil Co. resource potential of the Sierra Ladrones

A-21 NMBMMR OFR 454B Wilderness study area, Socorro County, New Basin, New Mexico: New Mexico Geological Mexico: New Mexico Bureau of Mines and Society, Guidebook 50, p. 337-353. Mineral Resources, Open-file report 179, 193 p., Connell, S.D., and Wells, S.G., 1999, Pliocene and 8 pls. Quaternary stratigraphy, soils, and tectonic Chamberlin, R.M., Pazzaglia, F.J., Wegman, K.W., geomorphology of the northern flank of the and Smith, G.A., 1999, Preliminary geologic Sandia Mountains, New Mexico: implications map of Loma Creston Quadrangle, Sandoval for the tectonic evolution of the Albuquerque County, New Mexico: New Mexico Bureau of Basin: New Mexico Geological Society, Mines and Mineral Resources, Open-file Digital Guidebook 50, p. 379-391. Map DM 25, scale 1:24,000. Connell, S.D., Love, D.W., Maldonado, F., Jackson, Chapin, C.E., and Cather, S.M., 1994, Tectonic P.B., McIntosh, W.C., and Eppes, M.C., 2000, Is setting of the axial basins of the northern and the top of the upper Santa Fe Group diachronous central Rio Grande rift: Geological Society of in the Albuquerque Basin? [abstract]: U.S. America, Special Paper 291, p. 5-25. Geological Survey, Open-File Report 00-488, p. Church, F.S., and Hack, J.T., 1939, An exhumed 18-20. erosion surface in the Jemez Mountains: Journal Connell, S.D., Love, D.W., Jackson-Paul, P.B., of Geology, v. 47, p. 613-629. Lucas, S.G., Morgan, G.S., Chamberlin, R.M., Cole, J. C., Grauch, V. J. S., Hudson, M. R., McIntosh, W.C., and Dunbar, N., 2001, Maldonado, F., Minor, S. A., Sawyer, D. A., and Stratigraphy of the Sierra Ladrones Formation Stone, B. R., 1999, Three-dimensional geologic type area, southern Albuquerque basin, Socorro modeling of the Middle Rio Grande basin County, New Mexico: Preliminary Results [abstract]: U. S. Geological Survey Open-file [abstract]: New Mexico Geology, v. 23, n. 2, p. Report 99-203, p. 25-26. 59. Connell, S.D., 1996, Quaternary geology and Cordell, L., 1978,Regional geophysical setting of the geomorphology of the Sandia Mountains Rio Grande rift: Geological Society of America, piedmont, Bernalillo and Sandoval Counties, Bulletin v. 89, n. 7, p. 1073-1090. central New Mexico: New Mexico Bureau of Cordell, L., 1979, Sedimentary facies and gravity Mines and Mineral Resources Open-File Report anomaly across master faults of the Rio Grande 425, 414 p., 3 pl. rift in New Mexico: Geology, v. 7, p. 201-205. Connell, S.D., 1997, Geology of the Alameda 7.5- Debrine, B., Spiegel, Z., and William, D., 1963, minute quadrangle, Bernalillo and Sandoval Cenozoic sedimentary rocks in Socorro valley, Counties, New Mexico: New Mexico Bureau of New Mexico: New Mexico Geological Society, Mines and Mineral Resources, Open-File Digital Guidebook 14, p. 123-131. Map 10, scale 1:24,000. Denny, C.S., 1940, Tertiary geology of San Acacia Connell, S.D., 1998, Geology of the Bernalillo 7.5- area: Journal of Geology, v. 48, p. 73-106. minute quadrangle, Sandoval County, New Dethier, D.P., Harrington, C.D., Aldrich, M.J., 1988, Mexico: New Mexico Bureau of Mines and Late Cenozoic rate of erosion in the western Mineral Resources, Open-File Digital Map 16, Española Basin, New Mexico: Evidence from scale 1:24,000. geologic dating of erosion surfaces: Geological Connell, S.D., and 10 others, 1995, Geology of the Society of America Bulletin, v. 100, p. 928-937. Placitas 7.5-minute quadrangle, Sandoval Dethier, D.P., 1999, Quaternary evolution of the Rio County, New Mexico: New Mexico Bureau of Grande near Cochiti Lake, northern Santo Mines and Mineral Resources, Open-File Digital Domingo Basin, New Mexico: New Mexico Map 2, scale 1:12,000 and 1:24,000, revised Bureau of Mines and Mineral Resources, Sept. 9, 1999. Guidebook 50, p. 371-378. Connell, S.D., Allen, B.D., and Hawley, J.W., 1998a, deVoogd, B., Serpa, L., and Brown, L.D., 1988, Subsurface stratigraphy of the Santa Fe Group Crustal extension and magmatic processes, from borehole geophysical logs, Albuquerque COCORP profiles from Death Valley and the area, New Mexico: New Mexico Geology, v. 20, Rio Grande rift: Geological Society of America, n. 1, p. 2-7. Bulletin, v. 100, p. 1550-1567. Connell, S.D., Allen, B.D., Hawley, J.W., and Evans, G.C., 1963, Geology and sedimentation along Shroba, R., 1998b, Geology of the Albuquerque the lower Rio Salado in New Mexico: New West 7.5-minute quadrangle, Bernalillo County, Mexico Geological Society, Guidebook 14, p. New Mexico: New Mexico Bureau of Mines and 209-216. Mineral Resources, Open-File Digital Geologic Erskine, D.W., and Smith, G.A., 1993, Map 17, scale 1:24,000. Compositional characterization of volcanic Connell, S.D., Koning, D.J., and Cather, S.M., 1999, products from a primarily sedimentary record: Revisions to the stratigraphic nomenclature of Geological Society of America Bulletin, v. 105, the Santa Fe Group, northwestern Albuquerque p. 1214-1222.

A-22 NMBMMR OFR 454B Galusha, T., 1966, The Zia Sand Formation, new border region: New Mexico Bureau of Mines and early to medial Miocene beds in New Mexico: Mineral Resources, Circular 104, p. 52-76. American Museum Novitiates, v.2271, 12 p. Hawley, J.W., Bachman, G.O., and Manley, K., Galusha, T., and Blick, J.C., 1971, Stratigraphy of the 1976, Quaternary stratigraphy of Basin and Santa Fe Group, New Mexico: American Natural Range and Great Plains provinces, New Mexico History Museum Bulletin, v. 144, article 1, 127 and Western Texas, in Mahaney, W.C., ed., p., 1 pl. Quaternary stratigraphy of North America: Gardner, J.N., Goff, F., Garcia, S., Hogan, R.C., Dowden, Hutchinson, and Ross, Stroudsburg, 1986, Stratigraphic relations and lithologic PA, p. 235-274. variations in the Jemez volcanic field, New Hawley, J.W., Haase, C.S., Lozinsky, R.P., 1995, An Mexico: Journal of Geophysical Research, v. 91, underground view of the Albuquerque Basin: n. B2, p. 1763-1778. New Mexico Water Resources Research Gawne, C., 1981, Sedimentology and stratigraphy of Institute, Report 290, p. 27-55. the Miocene Zia Sand of New Mexico, Heywood, C.E., 1992, Isostatic residual gravity Summary: Geological Society of America anomalies of New Mexico: U.S. Geological Bulletin, Part I, v. 92, n. 12, p. 999-1007. Survey, Water-Resources Investigations Report Gile, L.H., Hawley, J.W., and Grossman, R.B., 1981, 91-4065, 27 p. Soils and geomorphology in the Basin and Ingersoll, R.V., and Yin, A., 1993, Two stage Range area of southern New Mexico-Guidebook evolution of the Rio Grande rift, northern New to the Desert Project: New Mexico Bureau of Mexico and southern Colorado [abstract]: Mines and Mineral Resources, Memoir 39, 222 Geological Society of America, Abstracts with p. Programs, v. 25, n. 6, p. A-409. Gillentine, J.M., 1994, Petrology and diagenesis of Ingersoll, R.V., Cavazza, W., Baldridge, W.S., and the middle and lower Santa Fe Group in the Shafiqullah, M., 1990, Cenozoic sedimentation northern Albuquerque Basin, New Mexico: New and paleotectonics of north-central New Mexico: Mexico Bureau of Mines and Mineral Resources, implications for initiation and evolution of the Open-file Report 402C, Chapter 6, p. 1-50, 4 Rio Grande rift: Geological Society of America, app. Bulletin, v. 102, n. 9, p. 1280-1296. Goff, F., Gardner, J.N., and Valentine, G., 1990, Izett, G.A., and Obradovich, J.D., 1994, 40Ar/39Ar age Geology of St. Peter’s Dome area, Jemez constraints for the Jaramillo normal subchron Mountains, New Mexico: New Mexico Bureau and the Matuyama-Brunhes geomagnetic of Mines and Mineral Resources, Geologic Map, boundary: Journal of Geophysical Research, v. GM 69, scale 1:24,000. 99, n. B2, p. 2925-2934. Grauch, V. J. S., 1999, Principal features of high- Justet, L., 1999, The geochronology and resolution aeromagnetic data collected near geochemistry of the Bearhead Rhyolite, Jemez Albuquerque, New Mexico: New Mexico volcanic field, New Mexico [M.S. Thesis]: Las Geological Society, Guidebook 50, p. 115-118. Vegas, University of Nevada, 152 p. Grauch, V.J.S., Keller, G.R., and Gillespie, C.L., Karlstrom, K.E., Cather, S.M., Kelley, S.A., Heizler, 1999, Discussion of new gravity maps for the M.T., Pazzaglia, F.J., and Roy, M., 1999, Sandia Albuquerque Basin area: New Mexico Mountains and the Rio Grande rift: ancestry of Geological Society, Guidebook 50, 119-124. structures and history of deformation: New Hawley, J.W., ed., 1978, Guidebook to Rio Grande Mexico Geological Society, Guidebook 50, p. rift in New Mexico and Colorado: New Mexico 155-165. Bureau of Mines and Mineral Resources, Karlstrom, K., Connell, S.D. and others, 2001, Circular 163, 241 p. Geology of the Capilla Peak 7.5-minute Hawley, J. W., 1996, Hydrogeologic framework of quadrangle, Valencia and Torrance Counties, potential recharge areas in the Albuquerque New Mexico, New Mexico Bureau of Mines and Basin, central New Mexico: New Mexico Bureau Mineral Resources, Open-file Geologic Map 27, of Mines and Mineral Resources, Open-file scale 1:12,000. Report 402 D, Chapter 1, 68 p., appendix. Kautz, P.F., Ingersoll, R.V., Baldridge, W.S., Damon, Hawley, J.W., and Kernodle, J.M., in press, P.E., and Shafiqullah, M., 1981, Geology of the Overview of the hydrogeology and Espinaso Formation (Oligocene), north-central geohydrology of the northern Rio Grande basin, New Mexico: Geological Society of America Colorado, New Mexico, and Texas: Water Bulletin, v. 92, n. 12, Part I, p. 980-983, Part II, Resources Research Institute Report 312. p. 2318-2400. Hawley, J.W., Kottlowski, F.E., Strain, W.S., Seager, Kelley, S.A., Chapin, C.E., and Corrigan, J., 1992, W.R., King, W.E. and LeMone, D.V., 1969, The Late Mesozoic to Cenozoic cooling histories of Santa Fe Group in the south-central New Mexico the flanks of the northern and central Rio Grande rift, Colorado and New Mexico: New Mexico

A-23 NMBMMR OFR 454B Bureau of Mines and Mineral Resources, Albuquerque Basin, central New Mexico [Ph.D. Bulletin 145, 40 p. Dissert.]: Socorro, New Mexico Institute of Kelley, V.C., 1977, Geology of the Albuquerque Mining and Technology, 298 p. Basin, New Mexico: New Mexico Bureau of Lozinsky, R.P., 1994, Cenozoic stratigraphy, Mines and Mineral Resources, Memoir 33, 60 p. sandstone petrology, and depositional history of Kelley, V.C., 1979, Tectonics, middle Rio Grande the Albuquerque Basin, central New Mexico: rift, New Mexico in Riecker, R.E., ed., Rio Geological Society of America, Special Paper Grande rift: Tectonics and magmatism: 291, p. 73-82. American Geophysical Union, p. 57-70. Lozinsky, R.P., and Hawley, J.W., 1986, The Kelley, V. C. and Kudo, A. M., 1978, Volcanoes and Palomas Formation of south-central New related basaltic rocks of the Albuquerque-Belen Mexico-a formal definition: New Mexico Basin, New Mexico: New Mexico Bureau Mines Geology, v. 8, n. 4, p. 73-82. Mineral Resources, Circular 156, 30 p. Lozinsky, R.P., and Hawley, J.W., 1991, Cenozoic Koning, D.J., and Hallett, R.B., 2000, Geology of the structural evolution and depositional history in Turquoise Hill 7.5-minute quadrangle, Santa Fe three Rio Grande rift basins, central and southern County, New Mexico, New Mexico Bureau of New Mexico [abstract]: Geological Society of Mines and Mineral Resources, Open-file America, Abstracts with Programs, v. 23, n. 4, p. Geologic Map OF-GM 41, scale 1:24,000. A-44. Koning, D.J., and Personius, S.F., in review, Lozinsky, R.P., and Tedford, R.H., 1991, Geology Preliminary geologic map of the Bernalillo NW and paleontology of the Santa Fe Group, quadrangle, Sandoval County: U.S. Geological southwestern Albuquerque Basin, Valencia Survey, Miscellaneous Field Investigations Map, County, New Mexico: New Mexico Bureau of scale 1:24,000. Mines and Mineral Resources, Bulletin 132, 35 Kottlowski, F.E., 1953, Tertiary-Quaternary p. sediments of the Rio Grande Valley in southern Lozinsky, R.P., Love, D.W., and Hawley, J.W., 1991, New Mexico: New Mexico Geological Society, Geologic overview of Pliocene-Quaternary Guidebook 4, p. 144-148. history of the Albuquerque Basin, central New Lambert, P.W., 1968, Quaternary stratigraphy of the Mexico: New Mexico Bureau of Mines and Albuquerque area, New Mexico [Ph.D. Thesis]: Mineral Resources, Bulletin 137, p. 157-162. Albuquerque, University of New Mexico, 329 p. Lucas, S.G., Williamson, T.E., and Sobus, J., 1993, Large, E., and Ingersoll, R.V., 1997, Miocene and Plio-Pleistocene stratigraphy, paleoecology, and Pliocene sandstone petrofacies of the northern mammalian biochronology, Tijeras Arroyo, Albuquerque Basin, New Mexico, and Albuquerque area, New Mexico: New Mexico implications for evolution of the Rio Grande rift: Geology, v.15, n.1, p. 1-8. Journal of Sedimentary Research, Section A: Lucas, S.G., Cather, S.M., Abbott, J.C., and Sedimentary Petrology and Processes, v. 67, p. Williamson, T.E., 1997, Stratigraphy and 462-468. tectonic implications of Paleogene strata in the Leeder, M.R., Mack, G.H., and Salyards, S.L., 1996, Laramide Galisteo basin, north-central New Axial-transverse fluvial interactions in half- Mexico: New Mexico Geology, v. 19, p. 89-95. graben: Plio-Pleistocene Palomas Basin, Luedke, R.G., and Smith, R.L., 1978, Map showing southern Rio Grande rift, New Mexico, USA: distribution, composition, and age of late Basin Research, v. 12, p. 225-241. Cenozoic volcanic centers in Arizona and New Love, D. W., 1997, Petrographic description and Mexico: U.S. Geological Survey, Miscellaneous sources of chipped stone artifacts in Chaco Investigations Series, I-1091-A. Canyon, Appendix 3A, in F. J. Mathien, ed., Lundahl, A., and Geissman, J.W., 1999, Ceramics, lithics, and ornaments of Chaco Paleomagnetism of the early Oligocene mafic Canyon: National Park Service, Publications in dike exposed in Placitas, northern termination of Archaeology 18G, p. 610-633. the Sandia Mountains: New Mexico Geological Love, D.W., and Young, J.D., 1983, Progress report Society, Guidebook 50, p. 8-9. on the late Cenozoic geologic evolution of the Machette, M.N., 1978 a, Geologic map of the San lower Rio Puerco: New Mexico Geological Acacia Quadrangle, Socorro County, New Society, Guidebook 34, p. 277-284. Mexico: U.S. Geological Survey, Geologic Love, D.W., and Seager, W.R., 1996, Fluvial fans Quadrangle Map GQ-1415, scale 1:24,000. and related basin deposits of the Mimbres Machette, M.N., 1978 b, Dating Quaternary faults in drainage: New Mexico Geology, v. 18, n. 4, p. the southwestern United States using buried 81-92. calcic paleosoils: U.S. Geological Survey, Lozinsky, R.P., 1988, Stratigraphy, sedimentology, Journal of Research, v. 6, p. 369-381. and sand petrography of the Santa Fe Group and pre-Santa Fe Tertiary deposits in the

A-24 NMBMMR OFR 454B Machette, M.N., 1985, Calcic soils of the Albuquerque Basin, New Mexico: New Mexico southwestern United States: Geological Society Museum of Natural History and Science, of America Special Paper 203, p. 1-21. Bulletin 16, p. 217-240. Machette, M.N., Personius, S.F., Kelson, K.I., Haller, Morgan, G.S., and Williamson, T.E., 2000, Middle K.M., and Dart, R.L., 1998, Map and data for Miocene (late Barstovian) vertebrates from the Quaternary faults and folds in New Mexico: U.S. Benevidez Ranch local fauna, Albuquerque Geological Survey Open-File Report 98-821, Basin, New Mexico: New Mexico Museum of 443 p., 1 pl. Natural History and Science, Bulletin 16, p. 195- Mack, G.H., Salyards, S.L., and James, W.C., 1993, 207. Magnetostratigraphy of the Plio-Pleistocene Morgan, G.S., Lucas, S.G., Sealy, P.L., Connell, Camp Rice and Palomas Formations in the Rio S.D., and Love, D.W., 2000, Pliocene (Blancan) Grande rift of southern New Mexico: American vertebrates from the Palomas Formation, Arroyo Journal of Science, v. 293, p. 47-77. de la Parida, Socorro Basin, central New Mexico Mack, G.H., McIntosh, W.C., Leeder, M.R., and [abstract]: New Mexico Geology, v. 22, n. 2, p. Monger, H.C., 1996, Plio-Pleistocene pumice 47. floods in the ancestral Rio Grande, southern Rio Osburn, G.R., and Chapin, C.E., 1983, Nomenclature Grande rift, New Mexico, USA: Sedimentary for Cenozoic rocks of northeast Mogollon-Datil Geology, v. 103, p. 1-8. volcanic field, New Mexico: New Mexico Mack, G.H., Love, D.W., and Seager, W.R., 1997, Bureau of Mines and Mineral Resources, Spillover models for axial rivers in regions of Stratigraphic Chart 1. continental extension: the Rio Mimbres and Rio Newell, H.H., 1997, 40Ar/39Ar geochronology of the Grande in the southern Rio Grande rift, USA: Miocene silicic lavas of the Socorro-Magdalena Sedimentology, v. 44, p. 637-652. area, New Mexico [M.S. Thesis]: Socorro, New Maldonado, F., Connell, S.D., Love, D.W., Grauch, Mexico Institute of Mining and Technology, 190 V.J.S., Slate, J.L., McIntosh, W.C., Jackson, p. P.B., and Byers, F.M., Jr., 1999, Neogene Pazzaglia, F.J., and Wells, S.G., 1990, Quaternary geology of the Isleta Reservation and vicinity, stratigraphy, soils and geomorphology of the Albuquerque Basin, New Mexico: New Mexico northern Rio Grande rift: New Mexico Geological Society Guidebook 50, p. 175-188. Geological Society, Guidebook 41, p.423-430. Manley, K., 1978, Geologic map of Bernalillo NW Pazzaglia, F.J., and 10 others, 1999, Second-day trip quadrangle, Sandoval County, New Mexico: 2 road log, Albuquerque to San Ysidro, Loma U.S. Geological Survey Geologic, Quadrangle Creston, La Ceja, and Sand Hill fault: New Map GQ 1446, scale 1:24,000. Mexico Geological Society, Guidebook 50, p. May, J.S., and Russell, L.R., 1994, Thickness of the 47-66. syn-rift Santa Fe Group in the Albuquerque Personius, S.F., Machette, M.N., and Stone, B.D., Basin and its relation to structural style: 2000, Preliminary geologic map of the Loma Geological Society of America, Special Paper Machete quadrangle, Sandoval County, New 291, p. 113-123. Mexico: U.S. Geological Survey, Miscellaneous May, J.S., Kelley, S.A., and Russell, L.R., 1994, Field Investigations, MF-2334, scale 1:24,000, Footwall unloading and rift shoulder uplifts in ver. 1.0. the Albuquerque Basin: their relation to syn-rift Peters, L., 2001 a, 40Ar/39Ar geochronology results fanglomerates and appatite fission-track ages: from San Felipe Pueblo ashes [unpubl. data]: Geological Society of America, Special Paper New Mexico Geochronological Research 291, p. 125-134. Laboratory, Internal Report NMGRL-IR132, 3 Mayo, E.B., 1958, Lineament tectonics and some ore p., appendices. districts of the southwest: Mining Engineering, Peters, L., 2001 b, 40Ar/39Ar geochronology results v., 10, n. 11, p. 1169-1175. from San Felipe, Capilla Peak and Tome NE McIntosh, W.C., and Quade, J., 1995, 40Ar/39Ar quadrangles [unpubl. data]: New Mexico geochronology of tephra layers in the Santa Fe Geochronological Research Laboratory, Internal Group, Española Basin, New Mexico: New Report NMGRL-IR135, 3 p., appendices. Mexico Geological Society, Guidebook 46, p. Reneau, S.L., and Dethier, D.P., 1996, Pliocene and 279-287. Quaternary history of the Rio Grande, White Moore, J.D., 2000, Tectonics and volcanism during Rock Canyon and vicinity, New Mexico: New deposition of the Oligocene-lower Miocene Mexico Geological Society Guidebook 47, p. Abiquiu Formation in northern New Mexico 317-324. [M.S. Thesis]: Albuquerque, University of New Roy, M., Karlstrom, K., Kelley, S., Pazzaglia, F., and Mexico, 147 p., 3 pl. Cather, S., 1999, Topographic setting of the Rio Morgan G.S., and Lucas, S.G., 2000, Pliocene and Grande rift, New Mexico: assessing the role of Pleistocene vertebrate faunas from the flexural “rift flank uplift” in the Sandia

A-25 NMBMMR OFR 454B Mountains: New Mexico Geological Society, Spiegel, Z., 1961, Geology of the lower Guidebook 50, p. 167-174. area, New Mexico: New Mexico Geological Russell, L.R., and Snelson, S., 1994, Structure and Society, Guidebook 12, p.132-138. tectonic of the Albuquerque Basin segment of Spiegel, Z., and Baldwin, B., 1963, Geology and the Rio Grande rift: Insights from reflection water resources of the Santa Fe area, New seismic data: Geological Society of America, Mexico: U.S. Geological Survey, Water-Supply Special Paper 291, p. 83-112. Paper 1525, 25 p. Seager, W.R., Hawley, J.W., and Clemons, R., 1971, Stearns, C.E., 1953, Tertiary geology of the Galisteo- Geology of the San Diego Mountain area, New Tonque area, New Mexico: Geological Society Mexico: New Mexico Bureau of Mines and of America Bulletin, v. 64, p. 459-508. Mineral Resources, Bulletin 97, 38 p. Stearns, C.E., 1979, New K-Ar dates and the late Smith, G.A., 1995, Paleogeographic, volcanologic, Pliocene to Holocene geomorphic history of the and tectonic significance of the upper Abiquiu central Rio Grande region, New Mexico: Formation at Arroyo del Cobre, New Mexico: Discussion: Geological Society of America, New Mexico Geological Society, Guidebook 46, Bulletin, v. 90, n. 8, p. 799-800. p. 261-270. Stone, W.J., Lyford, F.P., Frenzel, P.F., Mizell, N.M., Smith, G.A., 2000, Oligocene onset of Santa Fe and Padgett, E.T., 1983, Hydrogeology and Group sedimentation near Santa Fe, New water resources of San Juan Basin, New Mexico: Mexico [abstract]: New Mexico Geology, v. 22, New Mexico Bureau of Mines and Mineral n. 2, p. 43. Resources, Hydrologic Report 6, 70 p., 7 pls., Smith, G.A., and Lavine, A., 1996, What is the microfiche tables. Cochiti Formation?: New Mexico Geological Tedford, R.H., 1982, Neogene stratigraphy of the Society, Guidebook 47, p. 219-224. northwestern Albuquerque Basin: New Mexico Smith, G.A., and Kuhle, A.J., 1998a, Geological Society, Guidebook 33, p. 273-278. Hydrostratigraphic implications of new geologic Tedford, R.H., and Barghoorn, S., 1997, Miocene mapping in the Santo Domingo Basin, New mammals of the Española and Albuquerque Mexico: New Mexico Geology, v. 20, n. 1, p. Basins, north-central New Mexico: New Mexico 21-27. Museum of Natural History and Science Bulletin Smith, G.A. and Kuhle, A.J., 1998b, Geology of the 11, p. 77-95. Santo Domingo Pueblo 7.5-minute quadrangle, Tedford, R.H., and Barghoorn, S., 1999, Santa Fe Sandoval County, New Mexico, New Mexico Group (Neogene), Ceja del Rio Puerco, Bureau of Mines and Mineral Resources, Open- northwestern Albuquerque Basin, Sandoval file Digital Geologic Map OF-DM 15, scale County, New Mexico: New Mexico Geological 1:24,000. Society, Guidebook 50, p. 327-335. Smith, G.A., and Kuhle, A.J., 1998c, U. S. Geological Survey, Sander Geophysics, Ltd., Hydrostratigraphic implications of new and Geoterrex-Dighem, 1999, Digital geological mapping in the Santo Domingo Basin, aeromagnetic data from the Sandoval-Santa Fe, New Mexico: New Mexico Geology, v. 20, n. 1, Belen, and Cochiti aeromagnetic surveys, p. 21-27 covering areas in Rio Arriba, Sandoval, Santa Smith, G.A., McIntosh, W.C., and Kuhle, A.J., 2001, Fe, Socorro, and Valencia Counties, New Sedimentologic and geomorphic evidence for Mexico: U. S. Geological Survey Open-File teeter-totter subsidence of the Santo Domingo Report 99-404, 1 CD-ROM. accommodation-zone basin, Rio Grande rift, Wells, S.G., Kelson, K.I., and Menges, C.M., 1987, New Mexico: Geological Society of America, Quaternary evolution of fluvial systems in the Bulletin, v. 113, n. 5, p. 561-574. northern Rio Grande rift, New Mexico and Smith, R.L., Bailey, R.A., and Ross, C.S., 1970, Colorado: implications for entrenchment and Geologic map of the Jemez Mountains, New integration of drainage systems, in Menges, Mexico: U.S. Geological Survey, Miscellaneous C.M., Enzel, Y., and Harrison, J.B.J., eds., Geological Investigations, I-571, scale Quaternary tectonics, landform evolution, soil 1:125,000. chronologies, and glacial deposits: northern Rio Smyth, D.G., and Connell, S.D., 1999, Hydrogeology Grande rift of New Mexico: Friends of the of the upper Santa Fe Group adjacent to the Sand Pleistocene-Rocky Mountain Cell Guidebook, p. Hill fault, Albuquerque Basin, NM [abstract]: 55-69. New Mexico Geology, v. 21, n. 2, p. 40. Woodward, L.A., 1977, Rate of crustal extension Soister, P.E., 1952, Geology of Santa Ana Mesa and across the Rio Grande rift near Albuquerque, adjoining areas, New Mexico [M.S. Thesis]: New Mexico: Geology, v. 5, p. 269-272. Albuquerque, University of New Mexico, 126 p, Woodward, L.A., 1987, Geology and mineral 3 pl. resources of Sierra Nacimiento and vicinity, New

A-26 NMBMMR OFR 454B Mexico: New Mexico Bureau of Mines and Mines and Mineral Resources, Circular 163, pl. Mineral Resources, Memoir 42, 84 p. 1. Woodward, L.A., and Menne, B., 1995, Down- Woodward, L.A., and Timmer, R.S., 1979, Geology plunge structural interpretation of the Placitas of Jarosa quadrangle, New Mexico: New Mexico area, northwestern part of Sandia uplift, central Bureau of Mines and Mineral Resources, New Mexico: Implications for tectonic evolution Geologic Map, GM 47, scale 1:24,000. of the Rio Grande rift: New Mexico Geological Wright, H.E., 1946, Tertiary and Quaternary geology Society, Guidebook 46, p. 127-133. of the lower Rio Puerco area, New Mexico: Woodward, L.A., and 6 others, 1978, Tectonic map Geological Society of America Bulletin, v. 57, n. of the Rio Grande rift region in New Mexico, 5, p. 383-456. Chihuahua, and Texas: New Mexico Bureau of

A-27 SUMMARY OF BLANCAN AND IRVINGTONIAN (PLIOCENE AND EARLY PLEISTOCENE) MAMMALIAN BIOCHRONOLOGY OF NEW MEXICO

GARY S. MORGAN and SPENCER G. LUCAS New Mexico Museum of Natural History, 1801 Mountain Road NW, Albuquerque, NM 87104

Significant mammalian faunas of Pliocene (latest Mountain LF from the Jornada basin. These faunas Hemphillian and Blancan) and early Pleistocene are characterized by the presence of taxa absent from (early and medial Irvingtonian) age are known from early Blancan faunas, including Geomys the Rio Grande and valleys of New (Nerterogeomys) paenebursarius, Equus cumminsii, Mexico. Fossiliferous exposures of the Santa Fe E. scotti, and , and the absence of South Group in the Rio Grande Valley, extending from the American immigrant mammals found in late Blancan Española basin in northern New Mexico to the faunas. The Pajarito LF is directly associated with a Mesilla basin in southernmost New Mexico, have fluvially recycled pumice dated at 3.12±0.10 Ma produced 21 Blancan and six Irvingtonian vertebrate (Maldonado et al., 1999). The Cuchillo Negro Creek assemblages (Fig. 1). A medial Irvingtonian fauna is and Elephant Butte Lake LFs are in close known from a cave deposit in the San Luis basin in stratigraphic association with a basalt flow dated at northernmost New Mexico (Fig. 2). Three Blancan 2.9 Ma. Magnetostratigraphy constrains the age of faunas occur in strata in the Gila River the Tonuco Mountain LF between 3.6 and 3.0 Ma. Valley in the Mangas and Duncan basins in The Mesilla A fauna from the Mesilla basin and southwestern New Mexico (Fig. 3). More than half of the Pearson Mesa LF from the Duncan basin are late these faunas contain five or more of Blancan in age (2.7-2.2 Ma). Both faunas record the mammals, and many have associated radioisotopic association of Nannippus with a South American dates and/or magnetostratigraphy, allowing for immigrant, from Mesilla A and correlation with the North American land-mammal Glossotherium from Pearson Mesa, restricting their biochronology (Figs. 2-3). age to the interval after the beginning of the Great Two diverse early Blancan (4.5-3.6 Ma) faunas American Interchange at about 2.7 Ma and before the are known from New Mexico, the Truth or of Nannippus at about 2.2 Ma. Consequences Local Fauna (LF) from the Palomas Magnetostratigraphy further constrains the Mesilla A basin and the Buckhorn LF from the Mangas basin. and Pearson Mesa faunas to the upper Gauss Chron, The Truth or Consequences LF contains five species just prior to the Gauss/Matuyama boundary at 2.58 of mammals indicative of the early Blancan: Ma. The Mesilla B and Virden faunas occur higher in cf. B. hilli, Notolagus lepusculus, the same stratigraphic sequences as the Mesilla A and Neotoma quadriplicata, Jacobsomys sp., and Pearson Mesa faunas, respectively, and are latest Odocoileus brachyodontus. Associated Blancan in age (2.2-1.8 Ma). Both faunas contain magnetostratigraphic data suggest correlation with taxa restricted to the Blancan, including the either the Nunivak or Cochiti subchrons of the Blancocamelus and Gigantocamelus from Mesilla B, Gilbert Chron (between 4.6 and 4.2 Ma), which is and lepophagus from Virden. The absence of consistent with the early Blancan age indicated by the Nannippus, and of Mammuthus and other genera that mammalian biochronology. The Truth or first appear in the Irvingtonian, suggest an age range Consequences LF is similar in age to the Verde LF between 2.2 and 1.8 Ma. Magnetostratigraphic data from Arizona, and slightly older than the Rexroad 3 from Mesilla B support a latest Blancan age. and Fox Canyon faunas from Kansas. The Buckhorn The Tijeras Arroyo fauna from the Albuquerque LF has 18 species of mammals, including two basin and the Tortugas Mountain and Mesilla C typical of the early Blancan, Mimomys poaphagus faunas from the Mesilla basin all include Mammuthus and Repomys panacaensis. The Buckhorn LF also is and other mammals indicative of an early similar in age to the Verde LF and has affinities with Irvingtonian age (1.8-1.0 Ma). The association of the Panaca LF from Nevada. Although the Buckhorn Mammuthus and in the Tortugas and Truth or Consequences LFs have few taxa in Mountain LF indicates an age younger than 1.8 Ma, common, the similarities of both faunas with the after the arrival of Mammuthus in North America Verde LF suggest they are close in age. from Eurasia and before the extinction of Eight faunas from the central and southern Rio Stegomastodon at about 1.2 Ma. The co-occurrence Grande Valley are medial Blancan in age (3.6-2.7 of Glyptotherium arizonae, Equus scotti, and the Ma), including the Pajarito and Belen faunas from the primitive mammoth M. meridionalis in Tijeras Albuquerque basin, the Arroyo de la Parida LF from Arroyo and Mesilla C is typical of southwestern early the Socorro basin, the Cuchillo Negro Creek and Irvingtonian faunas. Fossils of M. meridionalis from Elephant Butte Lake LFs from the Engle basin, the Tijeras Arroyo and Mesilla C are both closely Palomas Creek LF from the Palomas basin, the Hatch associated with dates of 1.6 Ma on pumice from the LF from the Hatch-Rincon basin, and the Tonuco lower Bandelier tuff, making them among the oldest B-29 NMBMMR OFR 454B dated in North America. San Antonio advanced species of Allophaiomys, Lemmiscus Mountain (SAM) Cave in northernmost New Mexico curtatus, and Microtus cf. M. californicus indicates a lacks large mammals, but the presence of the medial Irvingtonian age, between about 1.0 and 0.85 microtine rodents Mictomys kansasensis, an Ma.

Figure 1. Map of New Mexico showing the location of late Hemphillian, Blancan, and Irvingtonian fossil sites. The structural basins are named and indicated by stippling. Sites are numbered from north to south in the Rio Grande Valley (sites 1-29), followed by sites in the Gila River Valley (sites 30-33). 1. San Antonio Mountain (SAM) Cave, medial Irvingtonian; 2. Puyé Formation site, late Hemphillian; 3. Ancha Formation sites, late Blancan; 4. Santo Domingo, late Blancan; 5. Western Mobile, early Irvingtonian; 6. Loma Colorado de Abajo, early/medial Blancan; 7. Mesa del Sol, Blancan; 8. Tijeras Arroyo, early Irvingtonian; 9. Pajarito, medial Blancan; 10. Isleta, Blancan; 11. Los Lunas, Blancan; 12. Belen, medial Blancan; 13. Mesas Mojinas, Blancan; 14. Veguita, Blancan; 15. Sevilleta, Blancan; 16. Arroyo de la Parida, medial Blancan; 17. Fite Ranch, early Irvingtonian; 18. Silver Canyon, Blancan; 19. Elephant Butte Lake, medial Blancan; 20. Cuchillo Negro Creek, medial Blancan; 21. Truth or Consequences, early Blancan; 22. Palomas Creek, medial Blancan; 23. Hatch, medial Blancan; 24. Rincon Arroyo, late Blancan/early Irvingtonian; 25. Tonuco Mountain, medial Blancan; 26. Tortugas Mountain, early Irvingtonian; 27. Mesilla A, late Blancan; 28. Mesilla B, latest Blancan; 29. Mesilla C, early Irvingtonian; 30. Buckhorn, early Blancan; 31. Walnut Canyon, latest Hemphillian; 32. Pearson Mesa, late Blancan; 33. Virden, latest Blancan.

B-30 NMBMMR OFR 454B MIOCENE MAMMALIAN FAUNAS AND BIOSTRATIGRAPHY OF THE ZIA FORMATION, NORTHERN ALBUQUERQUE BASIN, SANDOVAL COUNTY, NEW MEXICO

GARY S. MORGAN and SPENCER G. LUCAS New Mexico Museum of Natural History, 1801 Mountain Road, NW, Albuquerque, NM 87104

Tedford (1981) reviewed the fossil mammal Arikareean age to the Standing Rock LF based on the faunas from late Cenozoic basins in New Mexico, association of the carnivores Daphoenodon, including the Albuquerque basin in the north-central Cephalogale, and Promartes cf. P. lepidus, and the part of the state. Early and middle Miocene mammal stenomyline camel Stenomylus cf. S. gracilis. faunas are known from the northern third of the Standing Rock Quarry is the type locality of the Albuquerque basin in Sandoval County, representing rodents Proheteromys cejanus and Ziamys tedfordi, the Arikareean, Hemingfordian, Barstovian, and named by Gawne (1975), and has also produced a Clarendonian land-mammal ”ages” (Galusha, 1966; nearly complete skeleton of the primitive rabbit Gawne, 1975, 1976; Tedford, 1981; Tedford and Archaeolagus (Gawne, 1976). The Standing Rock LF Barghoorn, 1997, 1999; Morgan and Williamson, is slightly younger than the well known late 2000). The Miocene vertebrate faunas from the Arikareean Agate Springs Quarry from the Harrison northern Albuquerque basin are derived from the Zia Formation in western Nebraska. Formation (Fig. 1). Galusha (1966) named the Zia The Blick Quarry and the stratigraphically “Sand” Formation with two members, the lower equivalent Quarry are in the middle of Piedra Parada Member and the upper Chamisa Mesa the Chamisa Mesa Member of the Zia Formation, Member. The Cañada Pilares Member of Gawne located along Arroyo Pueblo east of Jemez Pueblo on (1981) is similar in age to the Chamisa Mesa the Jemez Reservation (Galusha, 1966). Gawne Member, but is lithologically distinct. Connell et al. (1975) named the Blick LF for the combined fossil (1999) named the Cerro Conejo Member as the mammal assemblage from these two quarries. uppermost unit of the Zia Formation. Vertebrate Tedford (1981) and Gawne (1975, 1976) assigned an fossils occur in all four members of the Zia early Hemingfordian age to the Blick LF based on the Formation in the northern Albuquerque basin (Fig. presence of the dog Tomarctus optatus (placed in the 1). genus Protomarctus by Wang et al., 1999), the dog Cynarctoides acridens, the Pleurolicus cf. P. sulcifrons, and the pika (ochotonid) Oreolagus cf. O. nebrascensis. The Blick Quarry is the type locality of the endemic stenomyline camel Blickomylus galushai (Frick and Taylor, 1968). The Blick LF is early Hemingfordian in age, and is similar to the Thomas Farm LF from Florida, the Martin Canyon LF from Colorado, and the faunas from the Runningwater Formation in Nebraska (Gawne, 1975). The Jeep Quarry is located in the same general vicinity as the Blick Quarry in the Arroyo Pueblo drainage, but is higher stratigraphically, in the upper part of the Chamisa Mesa Member. Gawne (1975) named the Jeep LF for the mammalian assemblage from the Jeep Quarry and several nearby localities. Tedford (1981) assigned an early Hemingfordian age Figure 1. Lithostratigraphic and bistratigraphic to the Jeep LF based on the presence of the correl-ation of the Zia Formation in the northern Amphicyon, the mustelid Promartes, the camel Albuquerque basin. Protolabis, and the mylagaulid rodent Mesogaulus. Other mammals from the Jeep LF (Gawne, 1975) The Standing Rock Quarry is in the Piedra include the bear dog Ysengrinia, the canids Parada Member of the Zia Formation, located in Desmocyon thompsoni and Metatomarctus canavus, Arroyo Piedra Parada, south of San Ysidro on the Zia the pronghorn antilocaprid Merycodus, and the Reservation (Galusha, 1966). It has produced the camels Michenia and Blickomylus galushai. The Jeep oldest fossil mammal assemblage from the Zia Quarry is the type locality of the canid Cynarctoides Formation, the rich late Arikareean assemblage gawnae (Wang et al., 1999). The Jeep LF is early named the Standing Rock Local Fauna (LF) by Hemingfordian in age, slightly younger than the Gawne (1975). Tedford (1981) assigned a late Blick LF, and intermediate in age between medial

C-33 NMBMMR OFR 454B Hemingfordian faunas from the Runningwater locality that is part of the Cerro Conejo Member. Formation and the late Hemingfordian Sheep Creek Faunas from the Cerro Conejo Member along the Fauna, both from Nebraska (Gawne, 1975; Tedford, northern Ceja del Rio Puerco, from Cañada Navajo 1981). south to Cañada Pilares and Cañada Moquino, most The Kiva Quarry is in the Chamisa Mesa or of which are located on the Alamo Ranch, are similar Piedra Parada members of the Zia Formation in the to the Rincon Quarry assemblage. (Tedford, 1981) Jemez River area near Arroyo Ojito and Arroyo The Alamo Ranch sites are characterized by the Piedra Parada (Cañada de Zia and Cañada Piedra beaver Eucastor, the camels Aepycamelus, Michenia, Parada, respectively, of Galusha, 1966; Tedford, Protolabis, and , the antilocaprid 1981). The presence of the borophagine dogs Ramoceros, and Gomphotherium productum Paracynarctus kelloggi and Microtomarctus conferta (Tedford, 1981; Tedford and Barghoorn, 1999). The and a primitive species of the horse genus mammalian assemblages from the Cerro Conejo Protohippus indicates a late Hemingfordian age for Member on the Alamo Ranch are typical of the late the Kiva Quarry (Tedford, 1981; Wang et al., 1999). Barstovian (middle Miocene, 12-14 Ma; Tedford and The Kiva Quarry fauna is similar to mammalian Barghoorn, 1999). A late Barstovian age for the faunas from the Nambé Member of the Tesuque vertebrate faunas is supported by a K-Ar date of Formation in the Española basin in northern New 13.64 Ma on a fallout ash in the Cerro Conejo Mexico. Member (Tedford and Barghoorn, 1999). In Arroyo Ojito, and farther south along the Ceja Scattered, generally poorly documented del Rio Puerco, especially on the Alamo Ranch and Clarendonian mammal fossils are found in the upper Benavidez Ranch, faunas of late Barstovian age part of the Cerro Conejo Member on the Zia occur in the Cerro Conejo Member (usage of Connell Reservation between the San Ysidro and Zia faults of et al., 1999) of the Zia Formation (Tedford 1981; Connell et al. (1999), which are equivalent to the Tedford and Barghoorn, 1999; Morgan and Jemez and Rincon faults, respectively, of Galusha Williamson, 2000). The Benavidez Ranch LF is in (1966) and Tedford (1981). Another poorly the Cerro Conejo Member west of Rio Rancho in documented Clarendonian locality includes the southern Sandoval County. The Benavidez Ranch carnivore Epicyon and is near US-550 on the Santa mammalian fauna includes the Peraceras, Ana Reservation (R.H. Tedford, 1999, oral the camels Michenia, Procamelus, and Protolabis, commun.), where several volcanic ashes are the pronghorn antilocaprid Ramoceros, and the interbedded in the uppermost part of the Cerro proboscidean Gomphotherium productum (Morgan Conejo Member. One of these ashes correlates to one and Williamson, 2000). The Benavidez Ranch LF of the Trapper Creek tephra in Idaho, which is dated also has a diverse footprint fauna, including tracks at ~ 10.8 Ma (Personius et al., 2000). The age of this made by a small wading bird, small and medium- ash is consistent with the occurrence of the sized camels, a rhinoceros, a horse, a large felid, a Clarendonian horses Pliohippus cf. P. pernix, large borophagine canid, and a proboscidean Cormohipparion cf. C. occidentale, and a derived (Williamson and Morgan, 2001). The most age- species of Neohipparion (Galusha, 1966; Tedford, diagnostic taxon in the Benavidez Ranch LF is 1981). Eastward, across the Zia fault, and in the Gomphotherium, which first appears in southwestern Arroyo Arenoso drainage north of the Jemez River, faunas in the early middle Miocene at about 14.5 Ma, rocks that are probably correlative with the Cerro defining the beginning of the late Barstovian Conejo Member have produced similar Clarendonian (Tedford et al., 1987; Tedford and Barghoorn, 1997, fossils (Tedford, 1981). Deposits that may be 1999). The remainder of the Benavidez Ranch LF is correlative with the Cerro Conejo Member are consistent with a late Barstovian age. interbedded with the Chamisa Mesa basalt (Connell At Arroyo Ojito, the Rincon quarry of Galusha et al., 1999), which has a K-Ar date of about 10.4 Ma (1966) is in the lower 50 m of the Cerro Conejo type (Bailey and Smith, 1978). These two dates are section, and the Zia prospect is near the middle of the consistent with a Clarendonian age for the youngest Cerro Conejo section at Arroyo Ojito (S.D. Connell, faunas from the Cerro Conejo Member. 2000, oral commun.). The Rincon Quarry fauna The mammalian faunal succession from the Zia includes the borophagine canids ferox and Formation in the northern Albuquerque basin begins Paratomarctus temerarius and primitive species of in the late Arikareean and ends in the Clarendonian the horse genera Neohipparion and Pliohippus (between about 19-21 and 11 Ma), overlapping in age (Tedford, 1981; Wang et al., 1999). The Rincon with much of the better known faunal sequence from Quarry assemblage is similar to the late Barstovian the Española basin in northern New Mexico fauna from the Santa Cruz sites in the Pojoaque (Tedford, 1981). Late Arikareean faunas from the Member of the Tesuque Formation in the Española Aqiquiu Formation are similar in age to the Standing basin (Tedford, 1981). Rock LF in the Albuquerque basin. Early The Alamo Ranch site is another late Barstovian Hemingfordian sites comparable in age to the Blick (Tedford, 1981, Tedford and Barghoorn, 1999). and Jeep LFs appear to be absent from the Española

C-34 NMBMMR OFR 454B basin. Sites from the Nambé Member of the Tesuque Morgan, G. S. and Williamson, T. E., 2000, Middle Formation are similar to the late Hemingfordian Kiva Miocene (late Barstovian) vertebrates from the Quarry in the Albuquerque basin. There appears to be Benavidez Ranch Local Fauna, Albuquerque a hiatus in the northern Albuquerque basin sequence, basin, New Mexico; in S. G. Lucas, ed., New equivalent to the early Barstovian, and corresponding Mexico’s Fossil Record 2: New Mexico Museum to faunas from the Skull Ridge Member of the of Natural History and Science Bulletin 16, p. Tesuque Formation in the Española basin (Tedford, 195-207. 1981; Tedford and Barghoorn, 1999). This hiatus is Personius, S.F., Machette, M.N., and Stone, B.D., documented by magnetostratigraphy (Tedford and 2000, Preliminary geologic map of the Loma Barghoorn, 1999). Late Barstovian faunas from the Machete quadrangle, Sandoval County, New Rincon Quarry, Alamo Ranch, and Benavidez Ranch Mexico: U.S. Geological Survey, Misc. Field in the northern Albuquerque basin are comparable in Investigations, MF-2334, scale 1:24,000, ver. age to faunal assemblages in the Española basin from 1.0. the Pojoaque Member of the Tesuque Formation, in Tedford, R. H., 1981, Mammalian biochronology of particular the Santa Cruz sites (Tedford, 1981, fig. 2). the late Cenozoic basins of New Mexico: The youngest faunas from the Zia Formation are Geological Society of America Bulletin, Part I, Clarendonian in age, and are similar to several faunas v. 92, p. 1008-1022. in the Española basin, such as the Round Mountain Tedford, R. H., and Barghoorn, S. 1997. Miocene Quarry in the (Tedford, 1981). mammals of the Española and Albuquerque basins, north-central New Mexico; in Lucas, S. REFERENCES G., Estep, J. W., Williamson, T. E., and Morgan, G. S., eds., New Mexico’s fossil record 1: New Bailey, R. A. and Smith, R. L., 1978, Guide to the Mexico Museum of Natural History and Science, Jemez Mountains and Española basin: New Bulletin 11, p. 77-95. Mexico Bureau of Mines and Mineral Resources, Tedford, R. H., and Barghoorn, S. 1999. Santa Fe Circular 163, p. 184-196. Group (Neogene), Ceja del Rio Puerco, Connell, S. D., Koning, D. J., and Cather, S. M., northwestern Albuquerque basin, Sandoval 1999, Revisions to the stratigraphic County, New Mexico: New Mexico Geological nomenclature of the Santa Fe Group, Society, Guidebook 50, p. 327-335. northwestern Albuquerque Basin, New Mexico: Tedford, R. H., Galusha, T., Skinner, M. F., Taylor, New Mexico Geological Society, Guidebook 50, B. E., Fields, R. W., Macdonald, J. R., p. 337-354. Rensberger, J. M., Webb, S. D., and Whistler, D. Frick, C. and B. E. Taylor, 1968, A generic review of P., 1987, Faunal succession and biochronology the stenomyline camels: American Museum of the Arikareean through Hemphillian interval Novitates, n. 2353, 51 p. (late Oligocene through earliest Pliocene epochs) Galusha, T. 1966. The Zia Sand Formation, new in North America; In M. O. Woodburne (editor), early to medial Miocene beds in New Mexico. Cenozoic mammals of North America: American Museum Novitates, n. 2271, 12 p. Geochronology and biostratigraphy: Berkeley, Gawne, C. E., 1975, Rodents from the Zia Sand, University of Press, p. 153-210. Miocene of New Mexico: American Museum Wang, X, Tedford, R. H., and Taylor, B. E., 1999, Novitates, n. 2586, 25 p. Phylogenetic systematics of the Borophaginae Gawne, C. E., 1976, Lagomorphs from the Zia Sand, (: ): Bulletin of the American Miocene of New Mexico: American Museum Museum of Natural History, n. 243, 391 p. Novitates, n. 2608, 15 p. Williamson, T. E. and Morgan, G. S., 2001, Avian Gawne, C. E., 1981, Sedimentology and stratigraphy and mammalian tracks from the middle Miocene of the Miocene Zia Sand of New Mexico: (late Barstovian) Benavidez Ranch local fauna, Summary: Geological Society of America Albuquerque basin, New Mexico. New Mexico Bulletin, Part I, v. 92, p. 999-1007. Geology.

C-35 NMBMMR OFR 454B PLIOCENE MAMMALIAN BIOSTRATIGRAPHY AND BIOCHRONOLOGY AT LOMA COLORADO DE ABAJO, SANDOVAL COUNTY, NEW MEXICO

GARY S. MORGAN and SPENCER G. LUCAS New Mexico Museum of Natural History and Science, 1801 Mountain Rd. NW, Albuquerque, NM 87104

Loma Colorado de Abajo is a prominent hill cheek teeth. The fragmentary mandible lacks cheek within the city limits of Rio Rancho in Sandoval teeth, but can be identified as a member of the extinct County, about 20 km northwest of Albuquerque subgenus Geomys (Nerterogeomys) by the placement (Loma Machete quadrangle). Beginning in 1990 and of the mental foramen ventral to the masseteric crest continuing until 1996, Paul Knight collected several (Tomida, 1987). Geomys (Nerterogeomys) first intriguing specimens of rodents from indurated, fine- appears in the early Blancan and becomes extinct in grained reddish sandstones near the base of the the early Irvingtonian. The Loma Colorado pocket exposed section on the south-facing escarpment of gopher skulls are smaller than most described skulls Loma Colorado de Abajo (New Mexico Museum of of Geomys (Nerterogeomys), and compare most Natural History and Science [NMMNH] Site L- closely to the small species, G. minor, known from 1462). The fossil site is located just a few hundred the early Blancan Rexroad Fauna in Kansas and meters behind the recently built Rio Rancho High Verde LF in Arizona, and the medial Blancan Beck School, finished in the summer of 1997, although the Ranch LF in Texas and Benson Fauna in Arizona school did not exist when the fossils were collected. (Hibbard, 1967; Dalquest, 1978; Czaplewski, 1990). The fossiliferous level is in the Loma Barbon Repenning and May (1986) reported G. minor from Member in the upper part of the Arroyo Ojito the early Blancan Truth or Consequences LF from Formation of Connell et al. (1999), about 8 m below the Palomas Formation in Sierra County in central the base of the overlying Ceja Member of the same New Mexico. The Loma Colorado mandible is formation (Fig. 1). smaller than pocket gopher mandibles from the Morgan and Lucas (1999, 2000) described the Pajarito and Belen faunas in the Albuquerque basin vertebrate fossils as the Loma Colorado de Abajo referred to G. (Nerterogeomys) paenebursarius (see local fauna (LF), which is limited in diversity, Morgan and Lucas, 2000). The smaller species of G. consisting of just three taxa, a small land tortoise and (Nerterogeomys) that are most similar in size to the two rodent genera, Spermophilus and Geomys. The Loma Colorado Geomys (e.g., G. minor) are same stratum from which the rodent fossils were restricted to the Blancan, whereas the species that collected also contains numerous ichnofossils that survive into the Irvingtonian (e.g., G. anzensis, G. appear to be rodent burrows. The Loma Colorado de garbanii, and G. persimilis) are larger. Abajo LF is unique among New Mexico Blancan The age of the Loma Colorado de Abajo LF is faunas in consisting entirely of small, burrowing probably early or medial Blancan. Small species of vertebrates. Geomys (Nerterogeomys), such as G. minor, are A ground squirrel of the genus Spermophilus is typical of faunas of this age. Also, a medial to late represented in the Loma Colorado de Abajo LF by a Blancan fauna (older than 2.2 Ma) is known from the partial skull with P4 from a small species in the size Ceja Member of the Arroyo Ojito Formation in range of living S. tridecemlineatus. It is considerably Tijeras Arroyo, a unit that overlies the Loma Barbon smaller than Spermophilus cf. S. bensoni from the Member. The Loma Colorado de Abajo LF is Blancan of southeastern Arizona (Tomida, 1987), a stratigraphically below and thus older than the species tentatively identified from the early Blancan Blancan fauna from Tijeras Arroyo. However, these Buckhorn LF in southwestern New Mexico (Morgan two faunas have no taxa in common, so more detailed et al., 1997). The Loma Colorado Spermophilus skull biostratigraphic comparisons are not possible. is also smaller than S. pattersoni and S. matachicensis from the late Hemphillian Yepómera REFERENCES Fauna in northern Mexico (Wilson, 1949; Lindsay and Jacobs, 1985). Connell, S. D., Koning, D. J., and Cather, S. M., Three specimens from Loma Colorado de Abajo are 1999, Revisions to the stratigraphic provisionally referred to the primitive pocket gopher, nomenclature of the Santa Fe Group. Geomys (Nerterogeomys) minor, including a nearly northwestern Albuquerque basin, New complete skull, a rostrum with a complete dentition, Mexico: New Mexico Geological Society, and an edentulous left mandible. The two skulls are Guidebook 50, p. 337-353. identified as Geomys on the basis of their bisulcate upper incisors, unrooted cheek teeth, and absence of enamel on the posterior surface of P4. Earlier pre- Blancan geomyids such as Pliogeomys have rooted D-37 NMBMMR OFR 454A Czaplewski, N. J., 1990, The Verde local fauna: Small vertebrate fossils from the Verde Formation, Arizona: San Bernardino County Museum Association Quarterly, v. 37(3), p. 1-39. Dalquest, W. W., 1978, Early Blancan mammals of the Beck Ranch local fauna of Texas: Journal of Mammalogy, v. 59, p. 269-298. Hibbard, C. W., 1967, New rodents from the Late Cenozoic of Kansas: Papers of the Michigan Academy of Science, Arts, and Letters, v. 52, p. 115-131. Lindsay, E. H., and Jacobs, L. L., 1985, Pliocene small mammal fossils from Chihuahua, Mexico: Universidad Nacional Autónoma de Mexico, Instituto de Geología, Paleontología Mexicana Numero 51, p. 1-53. Morgan, G. S. and Lucas, S. G., 1999, Pliocene (Blancan) vertebrates from the Albuquerque basin, north-central new Mexico: New Mexico Geological Society, Guidebook 50, p. 363-370. Morgan, G. S. and Lucas, S. G., 2000, Pliocene and Pleistocene vertebrate faunas from the Albuquerque basin, New Mexico: New Mexico Museum of Natural History and Science, Bulletin 16, p. 217-240. Morgan, G. S., Sealey, P. S., Lucas, S. G., and Heckert, A. B., 1997, Pliocene (latest Hemphillian and Blancan) vertebrate fossils from the Mangas basin, southwestern New Mexico: New Mexico Museum of Natural History and Science, Bulletin 11, p. 97-128. Repenning, C. A., and May, S. R., 1986, New Figure 1. Stratigraphic section of the Loma Colorado evidence for the age of lower part of the de Abajo site. The top of section is at about 5530 ft Palomas Formation, Truth or Consequences, (1630 m) elevation and is less than 52 m below the New Mexico: New Mexico Geological projected top of the Llano de Albuquerque (local top Society, Guidebook 37, p. 257-260. of upper Santa Fe Group). Tomida, Y., 1987, Small mammal fossils and correlation of continental deposits, Safford and Duncan basins, Arizona, USA: National Science Museum, Tokyo, 141 p. Wilson, R. W., 1949, Rodents of the Rincón fauna, western Chihuahua, Mexico: Carnegie Institution , Publication 584, p. 165-176.

D-38 NMBMMR 454B PLIO-PLEISTOCENE MAMMALIAN BIOSTRATIGRAPHY AND BIOCHRONOLOGY AT TIJERAS ARROYO, BERNALILLO COUNTY, NEW MEXICO

SPENCER G. LUCAS and GARY S. MORGAN New Mexico Museum of Natural History and Science, 1801 Mountain Rd. NW, Albuquerque, NM 87104

Most of the vertebrate fossils from Tijeras The land tortoise Hesperotestudo and five Arroyo, located just south of the Albuquerque species of mammals, including Glyptotherium cf. G. International Airport in Bernalillo County, are arizonae, Equus scotti, Equus sp., Camelops sp., and derived from the Sierra Ladrones Formation and are Mammuthus meridionalis occur together in the early Irvingtonian in age (Lucas et al., 1993). Tijeras Arroyo section above the Blancan site (l- However, one locality (New Mexico Museum of 1458) discussed above (Lucas et al., 1993; Morgan Natural History and Science [NMMNH] site L-1458) and Lucas, 2000). These species constitute a fairly at the base of the exposed stratigraphic section in typical fauna of early Irvingtonian age. Three Tijeras Arroyo (Fig. 1) has produced two species that additional species of mammals, a small species of are indicative of a Blancan age. The fossils from this Equus, the llama Hemiauchenia macrocephala and site were derived from a sandstone comprising unit 1 the mammoth Mammuthus imperator, occur in the stratigraphic section of Lucas et al. (1993, fig. somewhat higher in the Tijeras Arroyo section than 2). The lowermost part of the section in Tijeras the remainder of the fauna, but probably are Arroyo, including unit 1, was recently referred to the Irvingtonian as well. Ceja Member of the Arroyo Ojito Formation A caudal osteoderm of a from Tijeras (Connell and Hawley, 1998; Connell et al., 1999). Arroyo (Lucas et al., 1993) probably is not diagnostic Both mammals identified from site L-1458 at the species level, although this specimen almost in the Tijeras Arroyo section, Hypolagus cf. H. certainly represents Glyptotherium arizonae. gidleyi and Equus cf. E. cumminsii, are typical of Tentative referral of this osteoderm to G. arizonae is Blancan faunas, and do not occur in the Irvingtonian. reasonable as its association with Mammuthus rules The extinction in the late Pliocene (about 2.2 Ma) of out a Blancan age, and the Rancholabrean G. several characteristic Blancan genera, including floridanum is restricted to the and Gulf Hypolagus, Borophagus, Rhynchotherium, and coastal plains (Gillette and Ray, 1981). The large Nannippus, is considered one of the most important horse Equus scotti is the most common mammal in biochronological events in the late Blancan (Lindsay the Tijeras Arroyo Irvingtonian fauna, represented by et al., 1984). The presence of Hypolagus thus mandibles, isolated teeth, and postcrania (Lucas et indicates that site L-1458 is older than 2.2 Ma. Equus al., 1993; Morgan and Lucas, 2000). E. scotti is the cf. E. cumminsii appears to be absent from early typical large horse in late Blancan and early Blancan faunas, so L-1458 is probably middle or Irvingtonian faunas in the southwestern United States early late Blancan in age. (Hibbard and Dalquest, 1966), and occurs in medial Ten stratigraphically higher localities in Tijeras Blancan through early Irvingtonian faunas in New Arroyo have produced a significant vertebrate fauna Mexico (Tedford, 1981; Morgan et al., 1998). A of early Irvingtonian age (Lucas et al., 1993; Morgan complete equid metacarpal from Tijeras Arroyo is and Lucas, 2000). More than 75 m of the Sierra more slender than metacarpals of E. scotti, and Ladrones Formation are exposed in Tijeras Arroyo, represents a second, smaller species of Equus consisting of sandstones, pumiceous sandstones, and (Hibbard and Dalquest, 1966; Harris and Porter, gravels, with minor amounts of mudstone and 1980). A partial skull of a small Equus occurs higher diatomite. These sediments represent axial river in the Tijeras Arroyo section. deposits of an ancestral Rio Grande. The most Lucas and Effinger (1991) and Lucas et al. distinctive lithologic chracteristic of these beds is the (1993) referred a mandible with left and right m3 presence of reworked Guaje Pumice derived from the from Tijeras Arroyo to the primitive mammoth Bandelier Tuff, Ar/Ar dated at 1.61 Ma (Izett and Mammuthus meridionalis on the basis of its low plate Obradovich, 1994), in the units associated with an count and extremely thick enamel. This is one of only Irvingtonian fauna (units 3-8 of Lucas et al., 1993). two records of mammoths from New Mexico referred An extensive flora of leaves and pollen from a to M. meridionalis, indicating that this fauna is localized volcanic ash bed was collected in the almost certainly early Irvingtonian. The other record Tijeras Arroyo section (NMMNH Site L-1445). The consists of several partial teeth, tentatively referred to Tijeras Arroyo flora indicates that the cottonwood M. meridionalis, from an early Irvingtonian fauna in forest or bosque currently found along the banks of the Mesilla basin (Vanderhill, 1986). Lucas et al the Rio Grande in New Mexico dates back to at least (1993) referred a left M3 in a maxillary fragment the early Pleistocene (Knight et al., 1996). from Tijeras Arroyo to the mammoth Mammuthus

E-39 NMBMMR OFR 454B imperator. The teeth of M. imperator are more New Mexico: Journal of Mammalogy, v. 61, p. advanced than M. meridonalis in having a higher 46-65. plate count, higher lamellar frequency, and thinner Hibbard, C. W., and Dalquest, W. W., 1966, Fossils enamel. The M. imperator specimen was found about from the Seymour Formation of Knox and 12 m higher in the section than the remainder of the Baylor Counties, Texas, and their bearing on Tijeras Arroyo fauna, and thus is somewhat younger, the late Kansan climate of that region: although an Irvingtonian age is still likely (Lucas et Contributions from the Museum of al., 1993). Paleontology, University of Michgian, v. 21, The presence of mammoths in unit 6 of Lucas et n. 1, 66 p. al. (1993) and above clearly establishes an Izett, G. A. and Obradovich, J. D, 1994, 40Ar/39Ar age Irvingtonian age for the upper part of the Tijeras constraints for the Jaramillo Normal Subchron Arroyo section, as Mammuthus is one of the defining and the Matuyama-Brunhes geomagnetic genera of the Irvingtonian NALMA. The first boundary: Journal of Geophysical Research, v. appearance of Mammuthus in the New World 99 (B2), p. 2925-2934. occurred sometime in the early Pleistocene (early Knight, P. J., Lucas, S. G., and Cully, A., 1996, Early Irvingtonian) between about 1.8 and 1.6 Ma. The Pleistocene (Irvingtonian) plants from the mammoth jaws from Tijeras Arroyo represent one of Albuquerque area, New Mexico: the oldest well-documented records of Mammuthus Southwestern Naturalist, v. 41, p. 207-217. from North America, based on an Ar/Ar age of 1.61 Lindsay, E. H., Opdyke, N. D., and Johnson, N. M., Ma on Guaje Pumice from the Sierra Ladrones 1984, Blancan-Hemphillian Land Mammal Formation in Tijeras Arroyo (Lucas et al., 1993; Izett Ages and late Cenozoic mammal dispersal and Obradovich, 1994; Lucas, 1995, 1996). Although events: Annual Review of Earth and the pumice date provides a maximum age for this Planetary Sciences, v. 12, p. 445-488. site, evidence from other pumice deposits of exactly Lucas, S. G., 1995, The Thornton Beach mammoth the same age farther south in the Rio Grande Valley and the antiquity of Mammuthus in North (Mack et al., 1996, 1998) indicates that the pumice is America: Quaternary Research, v. 43, p. very close in age to the fossils. The association of M. 263-264. meridionalis with Glyptotherium arizonae and Equus Lucas, S. G., 1996, The Thornton Beach mammoth: scotti is indicative of an early Irvingtonian age for the Consistency of numerical age and Tijeras Arroyo fauna. Correlative early Irvingtonian morphology: Quaternary Research, v. 45, p. faunas include the Tortugas Mountain LF (Lucas et 332-333. al., 1999, 2000) and Mesilla Basin Fauna C Lucas, S. G., and Effinger, J. E., 1991, Mammuthus (Vanderhill, 1986) from the Mesilla basin in southern from Lincoln County and a review of the New Mexico, Gilliland in Texas (Hibbard and mammoths from the Pleistocene of New Dalquest, 1966), and Holloman in Mexico: New Mexico Geological Society (Dalquest, 1977). Guidebook 42, p. 277-282. Lucas, S. G., Morgan, G. S. and Estep, J. W., 2000, REFERENCES Biochronological significance of the co- occurrence of the proboscideans , Connell, S. D. and Hawley, J. W., 1998, Geology of Stegomastodon, and Mammuthus in the lower the Albuquerque West 7.5-minute quadrangle, Pleistocene of southern New Mexico: New Bernalillo County, New Mexico: New Mexico Mexico Museum of Natural History and Bureau of Mines and Mineral Resources, Open Science, Bulletin 16, p. 209-216. File Digital Map 17, Scale 1:24,000. Lucas, S. G., Williamson, T. E., and Sobus, J., 1993, Connell, S. D., Koning, D. J., and Cather, S. M., Plio-Pleistocene stratigraphy, paleoecology, 1999, Revisions to the stratigraphic and mammalian biochronology, Tijeras nomenclature of the Santa Fe Group. Arroyo, Albuquerque area, New Mexico: northwestern Albuquerque basin, New New Mexico Geology, v. 15, p. 1-8, 15. Mexico: New Mexico Geological Society, Lucas, S. G., Morgan, G. S. Estep, J. W. Mack, G. Guidebook 50, p. 337-353. H., and Hawley, J. W., 1999, Co-occurrence of Dalquest, W. W., 1977, Mammals of the Holloman the proboscideans Cuvieronius, Stegomastodon, local fauna, Pleistocene of Oklahoma: and Mammuthus in the lower Pleistocene of Southwestern Naturalist, v. 22, p. 255-268. southern New Mexico: Journal of Vertebrate Gillette, D. D. and Ray, C. E., 1981, of Paleontology, v. 19, p. 595-597. North America: Smithsonian Contributions Mack, G. H., McIntosh, W. C., Leeder, M. R., and to Paleobiology, number 40, 255 p. Monger, H. C., 1996, Plio-Pleistocene Harris, A. H. and Porter, L. S. W., 1980, Late pumice floods in the ancestral Rio Grande, Pleistocene horses of Dry Cave, Eddy County, southern Rio Grande rift, USA: Sedimentary Geology, v. 103, p. 1-8.

E-40 NMBMMR 454B

Figure 1. Stratigraphic column of Sierra Ladrones and Arroyo Ojito Formation strata at mouth of Tijeras Arroyo.

E-41 NMBMMR OFR 454B

Mack, G. H., Salyards, S. L., McIntosh, W. C., and Morgan, G. S., Lucas, S. G., and Estep, J. W., 1998, Leeder, M. R., 1998, Reversal Pliocene (Blancan) vertebrate fossils from magnetostratigraphy and radioisotopic the near Tonuco geochronology of the Plio-Pleistocene Camp Mountain, Doña Ana County, southern New Rice and Palomas Formations, southern Rio Mexico: New Mexico Geological Society Grande rift: New Mexico Geological Guidebook, 49th Field Conference, p. 237- Society, Guidebook 49, p. 229-236. 249. Morgan, G. S. and Lucas, S. G., 2000, Pliocene and Tedford, R. H., 1981, Mammalian biochronology of Pleistocene vertebrate faunas from the the late Cenozoic basins of New Mexico: Albuquerque basin, New Mexico: New Geological Society of American Bulletin, Mexico Museum of Natural History and Part I, v. 92, p. 1008-1022. Science, Bulletin 16, p. 217-240. Vanderhill, J. B., 1986, Lithostratigraphy, vertebrate paleontology, and magnetostratigraphy of Plio-Pleistocene sediments in the Mesilla basin, New Mexico [PhD Dissertation]: Austin, University of Texas, 305 p.

E-42 LITHOSTRATIGRAPHY AND PLIOCENE MAMMALIAN BIOSTRATIGRAPHY AND BIOCHRONOLOGY AT BELEN, VALENCIA COUNTY, NEW MEXICO

GARY S. MORGAN and SPENCER G. LUCAS New Mexico Museum of Natural History and Science, 1801 Mountain Rd., NW, Albuquerque, NM 87104

DAVID W. LOVE New Mexico Bureau of Mines and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

INTRODUCTION BIOSTRATIGRAPHY

Extending south of Los Lunas volcano to Belen The New Mexico Museum of Natural History and into northern Socorro County, badlands and Science (NMMNH) has two collections of developed in the Arroyo Ojito Formation of Connell Blancan vertebrates from southwest of Belen in et al. (1999) are well exposed in an east-facing Valencia County. In 1992, Bill Wood collected escarpment just west of Interstate Highway 25 and vertebrate fossils about 5 km southwest of Belen several km west of the Rio Grande (Fig. 1). In 1982, (NMMNH Site L-3778). Fossils from this site John Young examined numerous sections exposed on include lower jaws of the gomphotheriid the east and west sides of the Llano de Albuquerque proboscidean Stegomastodon mirificus and and described four in his master’s thesis at the New postcranial elements of the horse Equus. Christopher Mexico Institute of Mining and Technology. The two Whittle and several students collected fossils from thickest sections exposed more than 100 m of upper conglomeratic sandstone and slightly indurated Santa Fe Group basin fill. As can be seen in the sandstone about 2 km southwest of Belen (NMMNH outcrops at the Belen site, cross-bedded gravel and Site L-3737), about 4 km north of site L-3778 and gravelly sands alternate up section with finer-grained just south of Camino del Llano Road (formerly units. Weak soils and eolian deposits are also Sosimo Padilla Road). Fossils from this site include a common. The gravel commonly has a suite of pebble snake, the mole Scalopus, the rodent Geomys, the types, including well rounded siliceous pebbles horse Equus, and a small antilocaprid. Because of the (recycled from Paleogene, Mesozoic, and upper close proximity of sites L-3737 and 3778 southwest Paleozoic units of the Colorado Plateau), basaltic, of Belen and their occurrence in similar strata intermediate, and silicic volcanic rocks, red granitic referred to the Arroyo Ojito Formation, the fossils rocks, silicified wood, sandstone concretions from these two sites are combined as the Belen Fauna (recycled Mesozoic), pycnodonte shell fragments (Morgan and Lucas, 2000). (Cretaceous; Hook and Cobban, 1977), carbonate The Belen Fauna (Morgan and Lucas, 2000) is rocks (upper Paleozoic and Neogene composed of five species of mammals, including travertines), and rare obsidian pebbles from East Scalopus (Hesperoscalops) cf. S. blancoensis, Grants Ridge, about 112 km northwest of here. The Geomys (Neterogeomys) cf. G. paenebursarius, presence of Grants Ridge obsidian indicates that Equus cf. E. calobatus, a small antilocaprid, and much of this section was derived from the ancestral Stegomastodon mirificus. A dentary with m1-m3 Rio San Jose fluvial system, which is presently a from the Belen Fauna is the first mole (family tributary to the Rio Puerco. Talpidae) ever reported from New Mexico, recent or Young (1982) compared amounts of Rb, Y, Zr fossil (Morgan and Lucas, 1999, 2000). This mole is and Sr in obsidian samples from East Grants Ridge to referred to Scalopus (Hesperoscalops), an extinct the same trace elements in the pebbles and found subgenus of Scalopus restricted to the Blancan. Three almost identical amounts, thereby demonstrating species of S. (Hesperoscalops) have been described, more than a visual match. Shackley (1998) showed S. sewardensis from the very early Blancan Saw that there were two similar but distinct sources of Rock Canyon LF in Kansas, S. rexroadi from the obsidian in the area of East Grants Ridge and was early Blancan Rexroad and Fox Canyon faunas in able to distinguish them by amounts of Zr, Y, and Kansas and the medial Blancan Beck Ranch LF in Nb, among other elements. Lipman and Mehnert Texas, and S. blancoensis from the late Blancan obtained an age of 3.2 ± 0.3 Ma for the East Grants Blanco LF in Texas (Hibbard, 1953; Dalquest, 1975, Ridge obsidian. 1978; Kurtén and Anderson, 1980). The Belen The obsidian is recognized in conglomeratic dentary is tentatively referred to S. blancoensis based units as deep as 53 m below the Llano de on its similarity to that species in size and Albuquerque surface, with a marked increase in morphological features. A dentary with a complete amounts above 27 m. The presence of this obsidian dentition from Belen is identified as the extinct constrains the age of the upper 50 m of section to less pocket gopher subgenus Geomys (Nerterogeomys). than 3 million old. F-43 NMBMMR OFR 454B Blancan Hudspeth and Red Light LFs of southwestern Texas (Strain, 1966; Akersten, 1972). The most common fossils in the Belen Fauna are postcranial elements of horses of the genus Equus, most of which are not diagnostic at the species level. A nearly complete metatarsal is tentatively referred to the large, stilt-legged horse, E. calobatus, a species known from the late Blancan Santo Domingo LF (Tedford, 1981) and from late Blancan and early Irvingtonian faunas in the Mesilla basin (Vanderhill, 1986). A well preserved pair of mandibles with right and left m2-m3 are referred to the gomphothere Stegomastodon mirificus. The presence of seven lophids on m3 separates this specimen from Rhynchotherium and Cuvieronius, and the highly complicated enamel with double trefoiling distinguishes the teeth from the more primitive species S. rexroadensis. Four mammals in the Belen Fauna are age diagnostic. The extinct subgenus Scalopus (Hesperoscalops) is restricted to the Blancan, and the species S. blancoensis occurs in the late Blancan. Geomys (Nerterogeomys) paenebursarius is known from two late Blancan faunas in southwestern Texas (Strain, 1966; Akersten, 1972), and the medial Blancan Pajarito LF in the northern Albuquerque basin (Tedford, 1981; Morgan and Lucas, 2000). Stegomastodon mirificus is known from the medial Blancan through the early Irvingtonian, and Equus calobatus occurs in the late Blancan and Irvingtonian (Kurtén and Anderson, 1980). The age of the Belen Fauna thus is either medial or late Blancan. S. blancoensis and E. calobatus occur in late Blancan faunas, but are not known from the medial Blancan, whereas G. (N.) paenebursarius and S. mirificus first appear in the medial Blancan. The lack of South American immigrants in the Belen Fauna suggests a medial Blancan age, although their absence could be related to biogeographic factors. Neotropical mammals are unknown from Blancan faunas in northern New Mexico; however, Glyptotherium occurs in two early Irvingtonian faunas in the Albuquerque basin, Tijeras Arroyo and Western Mobile. We tentatively place the Belen Fauna in the medial Blancan based on similarities with other medial Blancan faunas (e.g., Pajarito LF) from the Arroyo Ojito Formation in the Albuquerque basin.

REFERENCES

Figure 1. Stratigraphic column near Camino del Akersten, W. A., 1972, Red Light local fauna Llano (formerly Sosimo Padilla Road). Modified (Blancan) of the Love Formation, from Morgan and Lucas (2000) with projections of southeastern Hudspeth County, Texas: Pycnodonte and/or Exogyra valves and East Grants Texas Memorial Museum, Bulletin 20, 53 p. Ridge obsidian from Young (1982). Connell, S. D., Koning, D. J., and Cather, S. M., 1999, Revisions to the stratigraphic The morphology and size of this mandible are similar nomenclature of the Santa Fe Group, to the species G. (N.) paenebursarius, also identified northwestern Albuquerque basin, New from the Pajarito LF, and first described from the late

F-44 NMBMMR OFR 454B Mexico: New Mexico Geological Society, Morgan, G. S. and Lucas, S. G., 2000, Pliocene and Guidebook 50, p. 337-353. Pleistocene vertebrate faunas from the Dalquest, W. W., 1975, Vertebrate fossils from the Albuquerque basin, New Mexico: New Blanco local fauna of Texas: Occasional Mexico Museum of Natural History and Papers, The Museum, Texas Tech Science, Bulletin 16, p. 217-240. University, Number 30, 52 p. Shackley, M. S., 1998, Geochemical differentiation Dalquest, W. W., 1978, Early Blancan mammals of and prehistoric procurement of obsidian in the Beck Ranch local fauna of Texas: the Mount Taylor volcanic field, northwest Journal of Mammalogy, v. 59, p. 269-298. New Mexico: Journal of Archaeological Hibbard, C. W., 1953, The insectivores of the Science, v. 25, p. 1073-1082. Rexroad fauna, upper Pliocene of Kansas: Strain, W. S., 1966, Blancan mammalian fauna and Journal of Paleontology, v. 27, p. 21-32. Pleistocene formations, Hudspeth County, Hook, S. C., and Cobban, W. A.,1977, Pycnodonte Texas: Texas Memorial Museum, Bulletin Newberryi (Stanton)—Common guide fossil 10, 55 p. in Upper Cretaceous of New Mexico: New Tedford, R. H., 1981, Mammalian biochronology of Mexico Bureau of Mines and Mineral the late Cenozoic basins of New Mexico: Resources, Annual Report 1976-1977, p.48- Geological Society of American Bulletin, 54. Part I, v. 92, p. 1008-1022. Kurtén, B., and Anderson, E., 1980, The Pleistocene Vanderhill, J. B., 1986, Lithostratigraphy, vertebrate mammals of North America: Columbia paleontology, and magnetostratigraphy of University Press, New York, 442 p. Plio-Pleistocene sediments in the Mesilla Lipman, P. W., and Mehnert, H. H., 1980, Potassium- basin, New Mexico [PhD Dissertation]: argon ages from the Mount Taylor volcanic Austin, University of Texas, 305 p. field, New Mexico: U. S. Geological Survey Young, J.D., 1982, Late Cenozoic geology of the Professional Paper 1124B, p. B1-B8. lower Rio Puerco, Valencia and Socorro Morgan, G. S. and Lucas, S. G., 1999, Pliocene Counties, New Mexico [M.S. thesis]: (Blancan) vertebrates from the Albuquerque Socorro, New Mexico Institute of Mining basin, north-central new Mexico: New and Technology, 126 p., 1 pl. Mexico Geological Society, Guidebook 50, p. 363-370.

F-45 PLIOCENE MAMMALIAN BIOSTRATIGRAPHY AND BIOCHRONOLOGY AT ARROYO DE LA PARIDA, SOCORRO COUNTY, NEW MEXICO

SPENCER G. LUCAS and GARY S. MORGAN New Mexico Museum of Natural History and Science, 1801 Mountain Rd. NW, Albuquerque, NM 87104

In 1935, vertebrate fossils were first found in Formation, which has its type area about 100 km Arroyo de la Parida, about 6 km northeast of Socorro, farther south in Palomas Creek near Truth or Socorro County. Needham (1936) reported a Consequences in Sierra County (Lozinsky, 1986). complete pair of lower jaws of the gomphotheriid The Arroyo de la Parida LF is composed of ten proboscidean Rhynchotherium and a lower molar of species of vertebrates: the land tortoise the horse Plesippus (now considered a subgenus of Hesperotestudo; the ground sloth Megalonyx cf. M. Equus) from an exposure of sands and gravels of the leptostomus; three species of horses, Equus cf. E. Santa Fe Group on the southern side of Arroyo de la cumminsii, E. scotti, and E. simplicidens; two Parida, about 2 km east of its confluence with the Rio camelids, a large species of Camelops and a small Grande. Additional vertebrate fossils were collected species of Hemiauchenia; the small antilocaprid from this same exposure by students from the New Capromeryx; and two proboscideans, Mexico Institute of Mining and Technology (DeBrine Rhynchotherium falconeri and Stegomastodon sp. et al., 1963). This is a fairly typical faunal assemblage found in Curt Teichert, a well known expatriate German New Mexico Blancan sites, mostly consisting of invertebrate paleontologist, collected a sample of large grazing ungulates and dominated by horses of vertebrate fossils from the vicinity of Arroyo de la the genus Equus. Parida in 1953, and donated these fossils to the Five mammals from the Arroyo de la Parida LF American Museum of Natural History. The only are restricted to the Blancan, including Megalonyx locality information associated with Teichert’s leptostomus, Equus cumminsii, E. simplicidens, the sample was that the fossils were collected “about four large Camelops, and Rhynchotherium falconeri. The miles north of Socorro, New Mexico.” Based on the most age-diagnostic of these taxa is Rhynchotherium, general locality, preservation of the fossils, and the a gomphothere that became extinct in the late composition of the fauna, there is little doubt that Pliocene at about 2.2 Ma together with several other Teichert’s fossils are from the area that yields the characteristic genera of Blancan mammals. The lower Arroyo de la Parida local fauna (LF). The fossils jaws of R. falconeri from Arroyo de la Parida were collected by Teichert were summarized by Tedford collected near the top of the local section of the (1981), and include three species of horses, Equus Palomas Formation, suggesting that the entire fauna, simplicidens, E. cf. E. cumminsii, and E. cf. E. scotti, most of which occurs some 40 m lower in the section, the small antilocaprid Capromeryx, and the is older than 2.2 Ma. An early Blancan age for the gomphothere Stegomastodon. Arroyo de la Parida LF can be ruled out by the Lucas and Morgan (1996) described and presence of E. scotti and Camelops, both of which illustrated the mandibles of Rhynchotherium first first appear in New Mexico faunas during the medial mentioned by Needham (1936), and referred them to Blancan. The absence of South American immigrants the species R. falconeri, originally described from the suggests an age greater than 2.7 Ma. Megalonyx is Pliocene Blanco LF in Texas. Lucas and Morgan the only Blancan mammal of South American origin (1996) also summarized the biostratigraphy of the that was not a participant in the Great American Arroyo de la Parida LF, including fossils collected in Interchange. Megalonyx or its progenitor arrived 1996 by two students from New Mexico Tech, Ed from South America in the late Miocene about 9 Ma. Frye and Mike O’Keeffe. We visited the Arroyo de la M. leptostomus is fairly widespread in early through Parida area several times during 2000 and collected late Blancan faunas. The Arroyo de la Parida LF is numerous additional fossils from 15 different sites thus interpreted to be medial Blancan in age (3.6-2.7 (Morgan et al., 2000). Ma), and is similar to the Cuchillo Negro Creek LF The Arroyo de la Parida LF is derived from a 70- from the Palomas Formation in the Engle basin near m-thick sequence of sands and gravels that constitute Truth or Consequences. the axial river (ancestral Rio Grande) facies of the A Blancan fauna is known from the extreme Palomas Formation. Sandstone and conglomerate southern end of the Albuquerque basin near San derived from the eastern basin margin interfinger Acacia in northern Socorro County (Denny, 1940). with, and overlie these fluvial sediments. The strata This site is located just north of the Rio Salado on the in the vicinity of Arroyo de la Parida are located at western side of the Rio Grande, presumably from the the northern end of the Socorro basin, representing Sierra Ladrones Formation, as this site is near the one of the northernmost occurrences of the Palomas type area of the Sierra Ladrones Formation of G-47 NMBMMR OFR 454B Machette (1978). The fauna reported by Denny Denny, C.S, 1940, Tertiary geology of San Acacia (1940, p. 93) from the San Acacia site consists of the area: Journal of Geology, v. 48, p. 73-106. gomphothere Stegomastodon mirificus and an Lozinsky, R. P.,1986, Geology and late Cenozoic undetermined species of Equus. We have not history of the Elephant Butte area, Sierra examined these fossils, so the identifications are County, New Mexico: New Mexico Bureau taken from Denny’s paper and must be considered of Mines and Mineral Resources Circular tentative. The San Acacia site is similar to the middle 187, p. 1-40. to late Blancan Arroyo de la Parida local fauna, Lucas, S. G. and Morgan, G. S., 1996, The Pliocene derived from the Palomas Formation about 15 km proboscidean Rhynchotherium (Mammalia: farther south in the northern part of the Socorro basin Gomphotheriidae) from south-central New (Tedford, 1981; Lucas and Morgan, 1996). Mexico: Texas Journal of Science, v. 48, p. 311-318. REFERENCES Morgan, G. S., Lucas, S. G., Sealey, P. L., Connell, S. D., and Love, D. W., 2000, Pliocene DeBrine, B., Spiegel, Z., and William, D., 1963, (Blancan) vertebrates from the Palomas Cenozoic sedimentary rocks in Socorro Formation, Arroyo de la Parida, Socorro Valley, New Mexico: New Mexico basin, central New Mexico: New Mexico Geological Society, Guidebook 14, p. 123- Geology, v. 22, p. 47. 131. Needham, C. E., 1936, Vertebrate remains from Cenozoic rocks: Science, v. 84, p. 537. Tedford, R. H., 1981, Mammalian biochronology of the late Cenozoic basins of New Mexico: Geological Society of America Bulletin, v. 92, p. 1008-1022.

G-48 NMBMMR OFR 454B STRATIGRAPHY OF THE LOWER SANTA FE GROUP, HAGAN EMBAYMENT, NORTH-CENTRAL NEW MEXICO: PRELIMINARY RESULTS

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

STEVEN M. CATHER New Mexico Bureau of Mines and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, New Mexico 87801

INTRODUCTION lake and distal, streamflow-dominated piedmont setting. These members are associated with the Geologic mapping and stratigraphic studies of transition between the piedmont-slope and the basin- upper Oligocene through middle Miocene floor. An olivine basalt flow, about 9 m above the sedimentary rocks of the Santa Fe Group exposed in base at the type section, yielded a whole-rock the Hagan embayment constrain the initial 40Ar/39Ar date of 25.41±0.32 Ma (W.C. McIntosh, development of the Albuquerque Basin and Rio 2000, written commun.; Cather et al., 2000), which is Grande rift in north-central New Mexico. These consistent with an earlier K/Ar date of about 25.1±0.7 sedimentary rocks are exposed in the Albuquerque Ma (Kautz et al., 1981) at the northern tip of Basin along Arroyo de la Vega de los Tanos (herein Espinaso Ridge. called Tanos Arroyo) at the northeastern dip-slope of The basal contact of the Tanos Formation is Espinaso Ridge in the Hagan embayment of central sharp and slightly scoured. No angular unconformity New Mexico (Fig. 1). This paper presents with the underlying Espinaso Formation is apparent preliminary findings of geologic studies on two in outcrop. A continuous dip-meter log for the Pelto formations proposed for lower Santa Fe Group strata Blackshare Federal #1 well (Sec. 35, T14N, R6W, exposed in the Hagan embayment. San Felipe Pueblo NE quadrangle), drilled nearly 5 km south-southeast of the Tanos type section (on file STRATIGRAPHY OF TANOS ARROYO at the New Mexico Bureau of Mines and Mineral Resources in Socorro, New Mexico; Library of Stratigraphic sections were measured and Subsurface Data #26,091), indicates an angular described on the northeastern flank of Espinaso unconformity at about 460 m below land surface Ridge along Tanos Arroyo (Fig. 1). The Tanos (bls). Strata encountered in this well are oriented Arroyo section comprises two formation-rank units about N25°E, 10-12°NW below 460 m bls, and about that are informally subdivided into members and N60°W, 8°NE above. Thus we interpret the contact lithofacies units. These deposits are composed between the Espinaso and Tanos formations to be primarily of recycled volcanic and porphyritic unconformable. Restoration of Tanos Formation intrusive detritus derived from the adjacent Ortiz bedding to horizontal attitude indicates that the Mountains, on the footwall of the La Bajada fault Espinaso Formation was oriented about N10-12°W, (Fig. 2). The base of this succession is here called the 10-14°NE prior to deposition of the Tanos Tanos Formation, which overlies the volcaniclastic Formation. The dip-meter log does not show Oligocene Espinaso Formation (ca. 36-27 Ma, Kautz significant steepening in dips that would indicate the et al., 1981). The Tanos Formation is a succession of presence of a normal fault, which commonly have moderately tilted conglomerate, thin- to medium- dips of about 60°. Thus, the dip-meter log indicates bedded mudstone and tabular sandstone. The Tanos that the Espinaso Formation underwent an episode of Formation is 253 m thick at the type section (Figs. 2- deformation prior to deposition of the Tanos 3, TA1), where it is subdivided into a basal piedmont Formation. conglomerate member, a middle mudstone and The age of this unconformity is bracketed by a sandstone member, and an upper tabular sandstone K/Ar date of 26.9±0.6 Ma reported for a nepheline member. Ripple laminated sandstone beds are latite flow about 130 m below the top of the Espinaso common in the lower part of the middle member. Formation (Kautz et al., 1981) and the basalt dated These lithofacies occur in a distinct stratigraphic 25.41±0.32 Ma in the basal Tanos Formation. Thus, succession at the type section and are assigned to the hiatus represented by this unconformity at the informal member-rank terms. Mudstone beds thin to type section is thus less than 1.5 m.y. in duration, and the southeast, near the mouth of Arroyo del Tuerto likely spans a much shorter interval of time. If there (Fig. 3, TA; Arroyo Pinovetito of Stearns, 1953), was basal onlap of Tanos Formation to the east, then which is about 4 km south of the type section. The this unconformity might span an even shorter period Tanos Formation contains a mudstone and fluviatile of time towards the center of the basin, which was sandstone interval, suggesting deposition in a playa- presumably northwest of the type section. H-49 NMBMMR OFR 454B

Figure 1. Shaded relief map, illustrating the locations of major geographic features and the study area. Base produced from U.S. Geological Survey 30-m DEM data. Localities include the Pelto Blackshare Federal #1 (PBS), Tanos Arroyo sections (TA1, TA2), and selected localities mentioned in text.

The mapped extent of the Tanos Formation contrast, the Abiquiu Formation in the Abiquiu corresponds approximately with strata tentatively embayment, about 70 km northwest of the study area assigned to the Abiquiu Formation by Stearns (1953), (Smith, 1995; Moore, 2000), consists largely of and to strata Kelley (1979) correlated to the Zia epiclastic sediments derived from the Latir volcanic Formation. The Tanos Formation is in part, field of northern New Mexico. Paleocurrent temporally equivalent to the Abiquiu Formation measurements from the Tanos and Blackshare (Tedford, 1981; Moore, 2000). The Tanos Formation, formations indicate flow to the west-northwest, away however, is lithologically dissimilar to the Abiquiu from the highlands of the Ortiz Mountains (Fig. 4) Formation because it contains abundant locally and support the petrographic interpretations of Large derived volcanic detritus derived from the adjacent and Ingersoll (1997) that these deposits were derived Ortiz Mountains (Large and Ingersoll, 1997). In from the Ortiz Mountains.

H-50 NMBMMR OFR 454B

Figure 2. Simplified geologic map of the southeastern Santo Domingo sub-basin, illustrating locations stratigraphic sections along Tanos Arroyo (TA1 and TA2). Compiled from Cather and Connell (1998), Cather et al. (2000), Connell, (1998), Connell et al. (1995), and unpublished mapping.

The basal Santa Fe Group strata in the Hagan and hyperconcentrated-flow deposits laid down by embayment are older than the Zia Formation (Fig. 5) streams that originated form the Ortiz Mountains and and are not directly correlative as originally eastern margin of the Hagan embayment. suggested by Kelley (1977). The Zia Formation is Conglomerate beds are commonly lenticular and exposed 30-45 km to the west on the northwestern sandstone intervals commonly fine upward into margin of the Albuquerque Basin. The Hagan thinly bedded mudstone, which have upper contacts embayment contains a thick succession of mudstone that are commonly scoured by lenticular and fluvial sandstone derived from local sources to conglomerate of an overlying fining-upward the east, whereas the eolian-dominated lower Zia sequence. The upper boundary of the Tanos Formation was deposited by westerly winds and Formation is gradational and interfingers with the sparse, widely spaced southeast-flowing streams overlying Blackshare Formation. The contact is (Beckner and Mozley, 1998; Gawne, 1981). placed at the lowest lenticular pebbly to cobbly The Tanos Formation is conformably overlain by sandstone in this tabular sandstone/conglomeratic- a >700-m thick succession of sandstone, sandstone transition. This contact was chosen on the conglomerate, and minor mudstone herein called the basis of measured sections and differs slightly from Blackshare Formation, for the nearby Blackshare the mapped contact (Cather et al., 2000), which was Ranch, located in a tributary of Tanos Arroyo. The placed at the top of the highest, thickly bedded, Blackshare Formation is interpreted as stream-flow tabular sandstone.

H-51 NMBMMR OFR 454B

Figure 3. Composite stratigraphic section of the type locality (TA1) and Arroyo del Tuerto reference section (TA2) of the Tanos and Blackshare formations. Horizontal scale indicates approximate maximum grain size. The Pelto Blackshare Federal #1 (PBS), drilled about 6 km to the east, encountered similar deposits as interpreted from borehole geophysics and a continuous dip-meter log.

The type section of the Blackshare Formation is The sandstone member contains sandstone with about 312 m above the top of the Tanos Formation subordinate conglomerate and mudstone. type section. A complete section of the Blackshare An ash within the upper exposures of the Formation was not measured because the top is not Blackshare Formation was projected into the type recognized in the study area and exposures are section, where it is between 670-710 m (estimated commonly quite poor northeast of Tanos Arroyo. from geologic map of Cather et al., 2000) above the Discontinuous outcrops of the Blackshare Formation base. This ash yielded a single-crystal (on sanidine) extend 6 km east to the La Bajada fault. 40Ar/39Ar date of 11.65±0.38 Ma (W.C. McIntosh, The Blackshare Formation is locally 2000, written commun., Cather et al., 2000). Other differentiated into three mappable textural lithofacies fluvially recycled ashes, up to 3 m in thickness, (Cather et al., 2000), following methods proposed by occupy similar stratigraphic positions to the dated ash Cather (1997). These units interfinger, are not (Cather et al., 2000; Stearns, 1953); however, they superposed, and do not necessarily occur in any are too fine grained to be dated using the 40Ar/39Ar particular stratigraphic order. The conglomeratic technique. piedmont lithofacies consists of well cemented The Plio-Pleistocene Tuerto Formation overlies conglomerate and subordinate sandstone. The the Blackshare and Tanos formations with angular conglomeratic sandstone lithofacies consists of unconformity. The subhorizontally bedded Tuerto subequal amounts of sandstone and conglomerate. Formation overlies beds of the Tanos Formation that

H-52 NMBMMR OFR 454B tilt 27-36°NE. Dips in the Blackshare Formation nonquartzose lithic arkose of the subjacent Espinaso progressively decrease upsection, where stratal tilts Formation (Large and Ingersoll, 1997; Kautz et al., of 4-16°NE are observed stratigraphically above the 1981). 11.65 Ma ash in the Blackshare Formation; higher stratal tilts are commonly near faults. The top of the Blackshare Formation is cut by the La Bajada fault or is unconformably overlain by the subhorizontally bedded Plio-Pleistocene Tuerto Formation.

Figure 4. Rose diagram of paleocurrent data determined from gravel imbrication, channel orientation and cross stratification, indicating westward paleoflow from the Ortiz Mountains. Eight measurements were made in the basal Tanos Figure 5. Correlation chart, illustrating correlations Formation, which are not significantly different from of selected Santa Fe Group units at Arroyo Ojito in paleocurrent directions measured in the overlying the northwestern Calabacillas sub-basin (Connell et Blackshare Formation. Data compiled from geologic al., 1999), Hagan embayment (this study), and Santa map of the San Felipe Pueblo NE quadrangle and Fe embayment (Koning et al., this volume). The measured sections (Cather et al., 2000). Data is Cerros del Rio volcanic field is denoted by CdR. combined into 10° intervals and the correlation Triangles are dates (in Ma) from primary volcanic coefficient (r) is 0.85. units; boxes are recycled volcanic deposits; and shaded boxes are basaltic flows. Gravel in the Tanos and Blackshare formations are predominantly composed of monzanite and The stratigraphically lower Galisteo and andesite porphyry with sparse (<2%) rounded Diamond Tail formations are arkosic to subarkosic quartzite, , iron-stained sandstone, and and contain abundant quartz (Fig. 7). The abrupt hornfels (Fig. 6). The hornfels clasts are interpreted increase in quartz content of the Tanos Formation, to be thermally metamorphosed sandstone and shale relative to the subjacent Espinaso Formation, suggest from the Cretaceous Mesaverde Group or Mancos that older quartzose rocks were rapidly exposed on Shale, which was intruded by the Oligocene Ortiz the footwall of an emerging La Bajada fault. The porphyry in the footwall of the La Bajada fault (S. composition of the Tanos-Blackshare deposits Maynard, oral commun., 2000). Hornfels pebbles relative to the Espinaso and Galisteo formations do increase in abundance upsection in the interval above not suggest a simple mixing of the Espinaso and the measured section (Fig. 6). Sand in the Tanos and Galisteo and Diamond Tail formations, principally Blackshare formations is mostly lithic arkose and because of the greater abundance of lithic fragments feldspathic litharenite, and differs from the in Tanos-Blackshare succession. These data suggest

H-53 NMBMMR OFR 454B contributions from other lithic sources, or possibly early Miocene time. In their model, the western differences in grain size of the components analyzed margin of the basin was the depocenter until middle among the various studies compiled for Figure 7 or late Miocene time, when they propose that a (Ingersoll et al., 1984); however, compositional younger La Bajada fault and the range-bounding differences are probably too great to be accounted for faults of the Sandia Mountains (Sandia-Rincon by grain size alone. The rather sharp increase in faults) began to move and establish the generally quartz content across the Espinaso-Tanos contact east-tilted character of the northern Albuquerque indicate a rather abrupt change in the composition of Basin. upland drainages, rather than progressive unroofing of the formerly extensive volcanic cover of the Espinaso Formation. Fairly rapid exhumation of the basin border along major faults, such as the nearby La Bajada fault, could account for this abrupt change in source lithology. Oligo-Miocene movement along this fault might have also resulted in the development of the angular unconformity recognized on dip-meter log of the Pelto Blackshare Federal #1.

IMPLICATIONS

The base of the Tanos Formation is younger than the >30.48 Ma onset of deposition of the Nambé Member of the Tesuque Formation reported by Smith (2000) in the Española basin. The Nambé Member is one of the oldest basin-fill units of the Santa Fe Group in the Española basin. The Tanos Formation, however, is older than the eolianites of the Piedra Figure 6. Stacked bar graph illustrating upsection Parada Member of the Zia Formation, which overlie variations (from bottom to top) in gravel composition Eocene and Upper Cretaceous strata along the in the Tanos, Blackshare, and Tuerto formations. western margin of the Albuquerque Basin. The basal Porphyritic hypabyssal intrusive and volcanic rocks contact of the Piedra Parada Member contains derived from the Ortiz Mountains (Ortiz porphyry) scattered Oligocene volcanic clasts, indicating the dominate the basal Tanos Formation (TA2-u3). presence of formerly extensive, but probably thin, Gravel within the Blackshare Formation (TA1-u38, Oligocene deposits prior to deposition of the Zia u65, u67, and STA 55) tends to become more diverse Formation. Many of these volcanic cobbles and upsection. The Tuerto Formation (Tuerto 1-u6) is pebbles have been sculpted into ventifacts (Tedford typically more heterolithic and contains a greater and Barghoorn, 1999), suggesting that this boundary abundance of hornfels gravel than the underlying was subjected to prolonged exposure and erosion on Blackshare Formation. the hangingwall dip slope of the Calabacillas sub- basin. The presence of playa-lake mudstone and The eastward thickening of the Miocene Zia distal-piedmont sandstone on the hanging wall of the Formation (Connell et al., 1999) and preservation of La Bajada fault in the Hagan embayment suggests probable Oligocene sedimentary rocks in the Tamara that basin subsidence started with extensional block #1-Y well (Connell, Koning and Derrick, this faulting, probably along the La Bajada fault. volume), indicates that local stripping of Oligocene Definitive constraints on the onset of movement of volcanic rocks occurred during late Oligocene or the La Bajada fault are not available at this time, early Miocene time along the western margin of the however the abrupt change in sand composition basin. During this time, the Hagan embayment was across the Espinaso-Tanos boundary and the lack of receiving sediment. The unconformity between playa-lake deposits in the lower part of the Tesuque Tanos and Espinaso formations in the Pelto Formation in the Santa Fe embayment and Blackshare Federal #1 indicates late Oligocene southeastern Española basin suggests that the La deformation in the Hagan embayment. The Bajada fault was probably active since late Oligocene progressive decrease in stratal tilts upsection in the time. Tanos-Blackshare section indicates that deformation Oligo-Miocene activity on the La Bajada fault and concomitant sedimentation occurred after 25.4 does not support the two-stage model of development Ma. Deformation of the Tanos-Blackshare succession of the Albuquerque Basin (Large and Ingersoll, 1997; is partially constrained by a 2.8 Ma (K/Ar date) on a Ingersoll and Yin, 1993), which proposes that the basalt flow of the Cerros del Rio volcanic field northern portion of the Albuquerque Basin was a part (Bachman and Mehnert, 1978) that interfingers with of the Española basin (their Tesuque basin) during hypabssyal-intrusive- and volcanic-bearing

H-54 NMBMMR OFR 454B conglomerate correlated to the sub-horizontally lower than estimates of 600 m/m.y. for bedded Tuerto Formation. The presence of late stratigraphically higher, late Miocene, playa-lake Pliocene basalt flows interbedded with the Tuerto deposits of the Popotosa Formation in the southern Formation indicates that much of the stratal tilting in part of the Albuquerque Basin (Lozinsky, 1988). the Hagan embayment occurred prior to about 2.8 Ma. A paleomagnetic study of a 30.9 Ma mafic dike ACKNOWLEDGMENTS near the northern flank of the Sandia Mountains also indicates that much of the deformation and stratal tilt This study was funded in part by the New at the southern end of the Santo Domingo sub-basin Mexico Statemap Program of the National occurred after 30.9 Ma (Lundahl and Geissman, Cooperative Geologic Mapping Act of 1992 (P.W. 1999; see also Salyards et al., 1994; Brown and Bauer, Program Manager), and the New Mexico Golombek, 1985, 1986). Bureau of Mines and Mineral Resources (P.A. Scholle, Director). The authors thank Ms. Leanne Duree for allowing access through the Ball Ranch to conduct stratigraphic studies at Tanos Arroyo. Discussions with Steve Maynard, Gary Smith, John Hawley, and Charles Stearns improved this study. Comments on an earlier draft by John Hawley improved this paper. Kathleen McLeroy assisted in stratigraphic descriptions. Leo Gabaldon and Katherine Glesener drafted the geologic map.

REFERENCES

Bachman, G.O., and Mehnert, H.H., 1978, New K-Ar dates and the late Pliocene to Holocene geomorphic history of the central Rio Grande region, New Mexico: Geological Society of America Bulletin, v. 89, p. 283-292. Beckner, J.R, and Mozley, P.S., 1998, Origin and spatial distribution of early vadose and phreatic calcite cements in the Zia Formation, Albuquerque Basin, New Mexico, USA: Special Figure 7. Sandstone petrographic data (means and Publications of the International Association of fields of variations based on one standard deviation) Sedimentology, v. 26, p. 27-51. for undivided Galisteo-Diamond Tail Formations Brown, L.L., and Golombek, M.P., 1985, Tectonic (Tgd), upper Galisteo Formation (Tgu), Espinaso rotations within the Rio Grande rift: Evidence Formation (Te), Cordito (C) and Esquibel (E) from paleomagnetic studies: Journal of petrofacies (Abiquiu Formation correlatives, see Geophysical Research, v. 90, p. 790-802. Large and Ingersoll, 1997), and undivided Tanos and Brown, L.L., and Golombek, M.P., 1986, Block Blackshare formations (Tt, Tb, shaded). The rotations in the Rio Grande rift, New Mexico: hachured area denotes the Abiquiu Formation and Tectonics, v. 5, p. 423-438. sub-unit lithofacies in the Abiquiu embayment Cather, S.M., 1997, Toward a hydrogeologic (Moore, 2000). The Tanos and Blackshare formations classification of map units in the Santa Fe contain more quartz than the underlying Espinaso Group, Rio Grande Rift, New Mexico: New Formation, but contain more lithic fragments than Mexico Geology, v. 19, n. 1, p. 15-21 would be expected from mixing of Te and Tgd only. Cather, S.M., Connell, S.D., and Black, B.A., 2000, Data are summarized from Gorham (1979), Kautz et Preliminary geologic map of the San Felipe al. (1981), Large and Ingersoll (1997), and Moore Pueblo NE 7.5-minute quadrangle, Sandoval (2000). County, New Mexico: New Mexico Bureau of Mines and Mineral Resources, Open-file Digital Estimates of stratal accumulation rates (not Map DM-37, scale 1:24,000. corrected for compaction) suggest that the basal Connell, S.D., Cather, S.M., McIntosh, W.C., Santa Fe Group accumulated between 69-83 m/m.y. Dunbar, N., Koning, D.J., and Tedford, R.H., along the western margin (Tedford and Barghoorn, 2001, Stratigraphy of lower Santa Fe Group 1999) during early through middle Miocene time, and deposits in the Hagan embayment and near Zia about 72 m/m.y. along the eastern margin in the Pueblo, New Mexico: Implications for Oligo- Hagan embayment during late Oligocene through Miocene development of the Albuquerque basin Miocene time. These estimates are significantly

H-55 NMBMMR OFR 454B [abstract]: New Mexico Geology, v. 23, n. 2, p. Large, E., and Ingersoll, R.V., 1997, Miocene and 60-61. Pliocene sandstone petrofacies of the northern Connell, S.D., Koning, D.J., and Cather, S.M., 1999, Albuquerque Basin, New Mexico, and Revisions to the stratigraphic nomenclature of implications for evolution of the Rio Grande rift: the Santa Fe Group, northwestern Albuquerque Journal of Sedimentary Research, Section A: basin, New Mexico: New Mexico Geological Sedimentary Petrology and Processes, v. 67, p. Society, Guidebook 50, p. 337-353. 462-468. Connell, S.D., Pazzaglia, F.J., Koning, D.J., and Lozinsky, R.P., 1988, Stratigraphy, sedimentology, McLeroy, K., in preparation, Stratigraphic data and sand petrography of the Santa Fe Group and for measured sections of the Santa Fe Group pre-Santa Fe Tertiary deposits in the (upper Oligocene-Pleistocene) in the Hagan and Albuquerque Basin, central New Mexico [Ph.D. Santa Fe embayments, and northern flank of the dissert.]: Socorro, New Mexico Institute of Sandia Mountains, Sandoval and Santa Fe Mining and Technology, 298 p. Counties, New Mexico: New Mexico Bureau of Lundahl, A., Geissman, J.W., 1999, Paleomagnetism Mines and Mineral Resources, Open-file report. of the early Oligocene mafic dike exposed in Galusha, T., 1966, The Zia Sand Formation, new Placitas, northern termination of the Sandia early to medial Miocene beds in New Mexico: Mountains [mini paper]: New Mexico American Museum Novitiates, v. 2271, 12 p. Geological Society, Guidebook 50, p. 8-9. Gawne, C., 1981, Sedimentology and stratigraphy of Moore, J.D., 2000, Tectonics and volcanism during the Miocene Zia Sand of New Mexico, deposition of the Oligocene-lower Miocene Summary: Geological Society of America Abiquiu Formation in northern New Mexico Bulletin, Part I, v. 92, n. 12, p. 999-1007. [M.S. thesis]: Albuquerque, University of New Gorham, T.W., 1979, Geology of the Galisteo Mexico, 147 p., 3 pl. Formation, Hagan basin, New Mexico [M.S. Salyards, S.L., Ni, J.F., and Aldrich, M.J., Jr., 1994, thesis]: Albuquerque, University of New Variation in paleomagnetic rotations and Mexico, 136 p. kinematics of the north-central Rio Grande rift, Ingersoll, R.V., and Yin, A., 1993, Two stage New Mexico: Geological Society of America, evolution of the Rio Grande rift, northern New Special Paper 291, p. 59-71. Mexico and southern Colorado [abstract]: Smith, G.A., 1995, Paleogeographic, volcanologic, Geological Society of America, Abstracts with and tectonic significance of the upper Abiquiu Programs, v. 25, n. 6, p. A-409. Formation at Arroyo del Cobre, New Mexico: Ingersoll, R.V., Bullard, T.F., Ford, R.L., Grimm, New Mexico Geological Society, Guidebook 46, J.P., Pickle, J.D., Sares, S.W., 1984, The effect p. 261-270. of grain size on detrital modes; a test of the Smith, G.A., 2000, Oligocene onset of Santa Fe Gazzi-Dickinson point-counting method: Journal Group sedimentation near Santa Fe, New of Sedimentary Petrology, v. 54, n. 1, p. 103- Mexico [abstract]: New Mexico Geology, v. 22, 116. n. 2, p. 43. Kautz, P.F., Ingersoll, R.V., Baldridge, W.S., Damon, Stearns, C.E., 1953, Tertiary geology of the Galisteo- P.E., and Shafiqullah, M., 1981, Geology of the Tonque area, New Mexico: Geological Society Espinaso Formation (Oligocene), north-central of America Bulletin, v. 64, p. 459-508. New Mexico: Geological Society of America Tedford, R.H., 1981, Mammalian biochronology of Bulletin, v. 92, n. 12, Part I, p. 980-983, Part II, the late Cenozoic basins of New Mexico: p. 2318-2400. Geological Society of America Bulletin, Part I, Kelley, V. C., 1977, Geology of Albuquerque Basin, v. 92, p. 1008-1022. New Mexico: New Mexico Bureau of Mines and Mineral Resources, Memoir 33, 60 p.

H-56 NMBMMR 454B STRATIGRAPHY OF THE TUERTO AND ANCHA FORMATIONS (UPPER SANTA FE GROUP), HAGAN AND SANTA FE EMBAYMENTS, NORTH-CENTRAL NEW MEXICO

DANIEL J. KONING 14193 Henderson Dr., Rancho Cucamonga, CA 91739

SEAN D. CONNELL N.M. Bureau of Mines and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave., SE, Albuquerque, NM 87106

FRANK J. PAZZAGLIA Lehigh University, Department of Earth and Environmental Sciences, 31 Williams Dr., Bethlehem, PA 18015

WILLIAM C. MCINTOSH New Mexico Bureau of Mines and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

INTRODUCTION which we correlate to most of their type section. The upper quarter of their type Ancha section contains Geologic studies and 40Ar/39Ar dating of basalt flows and basaltic tephra of the Cerros del Rio subhorizontally bedded strata of the upper Santa Fe volcanic field, which was emplaced between 2.8 and Group in the vicinity of the Santa Fe and Hagan 1.4 Ma (David Sawyer, personal commun., 2001), embayments (Fig. 1) indicate that revision of the with the most voluminous activity occurring between Ancha and Tuerto formations are necessary. The 2.3-2.8 Ma (Woldegabriel et al., 1996; Bachman and Ancha and Tuerto formations are included in the Mehnert, 1978; Sawyer et al., 2001). Beneath the youngest strata of the Santa Fe Group, as defined by upper volcanic flows and is 12-17(?) Spiegel and Baldwin (1963), and consist of broad, m of strata, containing 1-5% quartzite clasts, that is thin alluvial aprons of Plio-Pleistocene age derived similar to a Pliocene deposit (unit Ta) mapped by from local uplands along the eastern margins of the Dethier (1997) that interfingers with Pliocene basalt Albuquerque and Española basins, Rio Grande rift, tephra of the Cerros del Rio volcanic field. north-central New Mexico (Fig. 2). The Ancha The lower Cañada Ancha section contains hard, Formation is composed mostly of granitic alluvium poorly sorted, grayish to brownish, pumiceous beds derived from the southeastern flank of the Sangre de (Fig. 3). Although subhorizontal at the type section, Cristo Mountains and is located in the Santa Fe these beds belong to a stratigraphic interval that embayment, a west-sloping piedmont associated with continues 10 km along-strike to the north, where they the southwestern flank of the Sangre de Cristo are overlain by younger strata dipping up to 5° to the Mountains. The Tuerto formation is composed mostly west (Fig. 2) (Koning and Maldonado, in of porphryitic intrusive, volcanic, and hornfels rocks preparation). Considering that the Ancha Formation derived from eroding Oligocene, volcanic edifices of is typically subhorizontal, the correlation of these the Ortiz Mountains and Cerrillos Hills and is pumiceous beds to strata that locally have been recognized mainly in the Hagan embayment (Fig. 1 appreciably deformed supports our interpretation that and 2). the lower type Ancha section should be assigned to the subjacent Tesuque Formation. We do not assign ANCHA FORMATION these granite-bearing deposits (commonly >90% granitic clasts) to the Chamita Formation because The Ancha Formation was defined by Spiegel paleocurrent data indicates general derivation from and Baldwin (1963, p. 45-50) for arkosic gravel, the east. In contrast, the more heterolithic, quartzite- sand, and silt, inferred to be late Pliocene to bearing deposits of the Chamita Fm were derived Pleistocene in age, that lie with angular unconformity from the north and northeast (cf. Galusha and Blick, upon moderately tilted Tesuque Formation near Santa 1971; Tedford and Barghoorn, 1993). Based on these Fe, New Mexico. They established a partial type interpretations and the presence of 8.48 Ma tephra, section for the Ancha Formation in Cañada Ancha, we propose that most of the Ancha Formation partial just north of the Santa Fe embayment (section CA, type section of Spiegel and Baldwin (1963) at Cañada Fig. 3). The lower 3/5 of their type section, however, Ancha is correlative to the Pojoaque Member of the contains an 8.48±0.14 Ma tephra and is lithologically Tesuque Formation. similar to the Pojoaque Member of the Tesuque Fm, I-57 NMBMMR 454B

I-58 NMBMMR 454B STRATIGRAPHY OF MIDDLE AND UPPER PLEISTOCENE FLUVIAL DEPOSITS OF THE RIO GRANDE (POST-SANTA FE GROUP) AND THE GEOMORPHIC DEVELOPMENT OF THE RIO GRANDE VALLEY, NORTHERN ALBUQUERQUE BASIN, CENTRAL NEW MEXICO

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, NM 87106

DAVID W. LOVE New Mexico Bureau of Mines and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

INTRODUCTION units. Furthermore, these geomorphic (i.e., “-alto”) terms were imported by Lambert (1968) for Alluvial and fluvial deposits inset against Plio- geomorphic surfaces described by Bryan and Pleistocene deposits of the upper Santa Fe Group McCann (1936, 1938) in the upper Rio Puerco valley (Sierra Ladrones and Arroyo Ojito formations) record without careful comparison of soil-morphologic and the development of the Rio Grande valley (Fig. 1) in geomorphic character of deposits within each the northern part of the Albuquerque basin since drainage basin. Thus, these geomorphic terms may early Pleistocene time. These fluvial terrace deposits not be applicable in the Rio Grande valley without contain pebbly to cobbly sand and gravel with additional work to establish surface correlations abundant rounded quartzite, subordinate volcanic, across the Llano de Albuquerque, the interfluve and sparse plutonic clasts derived from northern New between the Rio Grande and Rio Puerco valleys. Mexico. Although the composition of the gravel in Fluvial deposits discussed in this paper are, in these deposits is similar, they can be differentiated increasing order of age, the Los Padillas, Arenal, Los into distinct and mappable formation- and member- Duranes, Menaul, Edith, and Lomatas Negras rank units on the basis of landscape-topographic formations. position, inset relationships, soil morphology, and Although these inset ancestral Rio Grande units height of the basal contact above the Rio Grande as may be classified and differentiated determined from outcrop and drillhole data (Table 1; allostratigraphically, we consider them as lithologic Connell and Love, 2000). These fluvial deposits units of formation- and member rank that can be overlie, and locally interfinger with, alluvial deposits differentiated on the basis of bounding derived from paleo-valley margins and basin margin unconformities, stratigraphic position, and lithologic uplands (Fig. 2). Constructional terrace treads are not character. commonly preserved in older deposits, but are locally Recent geologic mapping of the Albuquerque well preserved in younger deposits. area (Cather and Connell, 1998; Connell, 1997, 1998; Kirk Bryan (1909) recognized two distinct types Connell et al., 1998; Love, 1997; Love et al., 1998; of ancestral Rio Grande deposits, his older Rio Smith and Kuhle, 1998; Personius et al., 2000) Grande beds (now called upper Santa Fe Group), and delineate a suite of inset fluvial deposits associated his younger, inset Rio Grande gravels (post Santa-Fe with the axial-fluvial ancestral Rio Grande. Inset Group). Lambert (1968) completed the first detailed terrace deposits record episodic incision and partial geologic mapping of the Albuquerque area and aggradation of the ancestral Rio Grande during proposed the terms Los Duranes, Edith, and Menaul Pleistocene and Holocene time. Lack of exposure and formations for prominent fluvial terrace deposits preservation of terrace deposits between Galisteo associated with the ancestral Rio Grande, however, Creek and Las Huertas Creek hampers correlation to these terms were not formally defined. Lambert partially dated terrace successions at the northern (1968) correctly suggested that a higher and older margin of the basin and in White Rock Canyon unit (his Qu(?)g) may be an inset fluvial deposit of (Dethier, 1999; Smith and Kuhle, 1998), southward the ancestral Rio Grande (Tercero alto terrace of into Albuquerque; however, correlation of these units Machette, 1985). using soil-morphology, landscape position, and We informally adopt three additional stratigraphic relationships provide at least limited lithostratigraphic terms to clarify and extend local constraints on the Rio Grande terrace Lambert's inset Rio Grande stratigraphy. We propose stratigraphy. lithostratigraphic terms to these fluvial deposits Soil-morphologic information derived from principally to avoid confusion in the use of profiles for fluvial and piedmont deposits are geomorphic terms, such as the primero, segundo, and described on well preserved parts of constructional tercero alto surfaces (Lambert, 1968), for lithologic geomorphic surfaces (Connell, 1996). Carbonate

J-67 NMBMMR OFR 454B morphology follows the morphogenetic classification buttress unconformity between this deposit and the system of Gile et al. (1966). underlying Arroyo Ojito Formation is exposed in the Loma Machete quadrangle (unit Qtag, Personius et al., 2000). The Lomatas Negras Formation is typically less than 16 ft (5 m) thick and consists of moderately consolidated and weakly cemented sandy pebble to cobble gravel primarily composed of subrounded to rounded quartzite, volcanic rocks, granite and sparse basalt (Fig. 3). This unit is discontinuously exposed along the western margin of the Rio Grande valley, where it is recognized as a lag of rounded quartzite-bearing gravel typically between about 215-245 ft (65-75 m) above the Rio Grande floodplain, which is underlain by the Los Padillas Formation (Fig. 4). The basal contact forms a low- relief strath cut onto slightly tilted deposits of the Arroyo Ojito Formation. The top is commonly eroded and is commonly overlain by middle Pleistocene alluvium derived from drainages heading in the Llano de Albuquerque. Projections of the base suggest that it is inset against early Pleistocene aggradational surfaces that define local tops of the Santa Fe Group, such as the Las Huertas and Sunport geomorphic surfaces (Connell et al., 1995, 1998; Connell and Wells, 1999; Lambert, 1968). Correlative deposits to the south (Qg(?) of Lambert, 1968) underlie the late-middle Pleistocene Figure 1. Shaded relief image of the northern part of (156±20 ka, Peate et al., 1996) Albuquerque the Albuquerque Basin (derived from U.S. Volcanoes basalt (Figs. 3-4). Projections of the Geological Survey 10-m DEM data) illustrating the Lomatas Negras Formation north of Bernalillo are approximate locations of terrace risers (hachured limited by the lack of preserved terraces, so, we lines), the Sunport surface (SP), stratigraphic sections provisionally correlate these highest gravel deposits (1-5), and cross section lines (A-F). with the Lomatas Negras Formation, recognizing the possibility that additional unrecognized terrace levels and deposits may be present along the valley margins. Similar deposits are recognized near Santo Domingo (Qta1 of Smith and Kuhle, 1998), which contain the ca. 0.66 Ma Lava Creek B ash from the Yellowstone area of Wyoming. A gravel quarry in the Pajarito Grant (Isleta quadrangle) along the western margin of the Rio Grande valley exposes an ash within an aggradation succession of fluvial sand and gravel. This ash has been geochemically correlated to the Lava Creek B (N. Dunbar, 2000, personal commun.) It lies within pebbly to cobbly sand and gravels that grade upward into a succession of sand with lenses of pebbly sand. This unit is Figure 2. Block diagram of geomorphic relationships slightly lower, at ~46 m above the Rio Grande, than among entrenched post-Santa Fe Group deposits Lomatas Negras deposits to the north, suggesting the along the western piedmont of the Sandia Mountains presence of additional unrecognized middle and east of the Rio Grande valley (from Connell and Pleistocene fluvial units, or intrabasinal faulting has Wells, 1999). down-dropped the Pajarito Grant exposures. The Lomatas Negras Formation is interpreted to be inset Lomatas Negras Formation against the Sunport surface, which contains a 1.26 Ma ash near the top of this Santa Fe Group section in The highest and presumably oldest preserved Rio Tijeras Arroyo. These stratigraphic and geomorphic Grande terrace deposit in the Albuquerque-Rio relationships indicate that the Lomatas Negras Rancho area is informally called the Lomatas Negras Formation was deposited between about 1.3 and 0.7 Formation for Arroyo Lomatas Negras, where a Ma.

J-68 NMBMMR 454B Table 1. Summary of geomorphic, soil-morphologic, and lithologic data for ancestral Rio Grande fluvial, piedmont and valley border deposits, listed in increasing order of age.

Unit Height above Thickness Carbonate Geomorphic/stratigraphic position Rio Grande (m) Morphology (m) Qrp 0 15-24 0 Lowest inset deposit; inner valley floodplain. Qay 0-3 <21 0, I Inset against Qpm; grades to Qrp. Qra 15 3-6 II+ Primero alto surface, inset against Qrd. Qam, Qpm ~65, eroded 45 III Alluvial deposits west of Rio Grande valley; top Overlies Qrd. Qrd 44-48 6-52 II+ Segundo alto surface, inset against Qre Qpm 8-30 15-51 II+, III+ Piedmont deposits of Sandia Mts; east of Rio Grande valley; interfingers with Qrm. Qrm 26-36 3 II+ Overlies Qpm and Qre; may be correlative to part of Qrd. Qre 12-24, eroded 3-12 not determined Inset against Qrl, inset by Qrd; underlies Qpm top with stage III + carbonate morphology. Qao, Qpo ~100, eroded <30 III to IV Overlies Qrl; inset by Qpm and Qre. top Qrl ~46-75, eroded 5-20 III, eroded Inset against Sunport surface. Contains ash top correlated to the Lava Creek B. Las ~120 --- III+ Local top of Sierra Ladrones Formation Huertas SP ~95 --- III+ Sunport surface of Lambert (1968): youngest Santa Fe Group constructional basin-floor surface.

Edith Formation (Connell, 1996). The Edith Formation unconformably overlies tilted sandstone of the The Edith Formation is a 10-40 ft (3-12 m) thick Arroyo Ojito and Sierra Ladrones formations and is deposit that typically comprises a single upward overlain by piedmont alluvium derived from the fining sequence of basal gravel and overlying sandy Sandia Mountains (Fig. 5). Where the top of the to muddy floodplain deposits. The Edith Formation Edith Formation is preserved, it typically contains serves as a useful and longitudinally extensive weakly developed soils with Stage I carbonate marker along the eastern margin of the Rio Grande morphology. This weak degree of soil development valley, between Albuquerque and San Felipe Pueblo, suggests that deposition of piedmont and valley New Mexico. This fluvial deposit can be physically border fan sediments occurred shortly after correlated across 33 km, from its type area in deposition of the Edith Formation. Albuquerque (Lambert, 1968, p. 264-266 and p. 277- The Edith Formation contains Rancholabrean 280), to near Algodones, New Mexico (Lambert, fossils, most notably Bison, Mastodon, Camelops, 1968; Connell et al., 1995; Connell, 1998, 1997; and and Equus (Lucas et al., 1988). Lambert (1968) Cather and Connell, 1998). The Edith Formation is a considered the Edith Formation to represent a late poorly to moderately consolidated, locally cemented Pleistocene terrace deposited during the latest deposits of pale-brown to yellowish-brown gravel, Pleistocene glacial events. Soils developed in these sand and sandy clay that forms laterally extensive piedmont deposits exhibit moderately developed Bt outcrops along the inner valley escarpment of the Rio and Btk horizons with moderately thick clay films Grande. Commonly recognized as an upward-fining and Stage III+ carbonate morphology, suggesting a succession of a 7-26 ft (2-8 m) thick, basal quartzite- middle Pleistocene age for these deposits (Connell, rich, cobble gravel that grades up-section into a 13-32 1996; Connell and Wells, 1999). ft (4-10 m) thick succession of yellowish-brown sand The base of the Edith Formation forms a and reddish-brown mud. The upper contact is locally prominent strath that lies about 40-80 ft (12-24 m) marked by a thin, white diatomite between Sandia above the Rio Grande floodplain and is about 30 m Wash and Bernalillo. Gravel contains ~30% rounded higher than the base of the Los Duranes Formation quartzite and ~40% volcanic rocks with subordinate (Connell, 1998). The elevation of this basal strath is granite, metamorphic, and sandstone clasts, and lower than the base of the Lomatas Negras Formation sparse, rounded and densely welded Bandelier Tuff suggesting that the Edith Formation is inset against

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Figure 3. Stratigraphic and drillhole sections of Pleistocene fluvial deposits of the ancestral and modern Rio Grande along the Rio Grande valley: 1) Los Padillas Formation at the Black Mesa-Isleta Drain piezometer nest; 2) Arenal Formation at Efren quarry (modified from Lambert, 1968; Machette et al., 1997); 3) Los Duranes Formation at the Sierra Vista West piezometer nest (data from Chamberlin et al., 1998); 4) Edith and Menaul formations at Sandia Wash (Connell, 1996); and 5) Lomatas Negras Formation at Arroyo de las Calabacillas and Arroyo de las Lomatas Negras. the Lomatas Negras Formation. A partially exposed Formation. Soils on the primero alto terrace are buttress unconformity between eastern-margin weakly developed (stage I to II+ carbonate piedmont alluvium and upper Santa Fe Group morphology, Machette et al., 1997) compared to deposits marks the eastern extent of this unit. This piedmont deposits overlying the Edith Formation. unconformity is locally exposed in arroyos between Therefore, it is likely that the gravels underlying the Algodones and Bernalillo, New Mexico. primero alto terrace are probably much younger than Lambert (1968) recognized the unpaired nature the Edith Formation. Therefore, if the Edith of terraces in Albuquerque, but assigned the Edith Formation is older than the Los Duranes Formation Formation to the topographically lower primero alto (see below), it was deposited prior to about 100-160 terrace, which is underlain by the Los Duranes ka. Formation in SW Albuquerque. Lambert (1968) The Edith Formation may correlate to fluvial correlated the Edith Formation with the primero alto terrace deposits near Santo Domingo Pueblo (Smith terrace, and therefore interpreted it to be younger and Kuhle, 1998). Deposits at Santo Domingo than the Los Duranes Formation. The primero alto Pueblo are approximately 30-m thick and about 30- terrace is the lowest fluvial-terrace tread in SW 35 m above the Rio Grande (Qta3 of Smith and Albuquerque and is underlain by rounded pebbly Kuhle, 1998). The lack of strongly developed soils sandstone that is inset against the Los Duranes between the Edith Formation and interfingering

J-70 NMBMMR OFR 454B middle Pleistocene piedmont alluvium suggests that The terrace tread (top) of the Los Duranes the Edith Formation was deposited closer in time to Formation is locally called the segundo alto surface the Los Duranes Formation. Thus, the Edith in the Albuquerque area (Lambert, 1968; Hawley, Formation was deposited between 0.66 and 0.16 Ma, 1996), where it forms a broad constructional surface and was probably laid down during the later part of west of the Rio Grande. Kelley and Kudo (1978) the middle Pleistocene. called this terrace the Los Lunas terrace, near Isleta Pueblo, however, we support the term Los Duranes Los Duranes Formation Formation as defined earlier by Lambert (1968). The Los Duranes Formation represents a major The Los Duranes Formation of Lambert (1968) aggradational episode that may have locally buried is a 40-52 m fill terrace consisting of poorly to the Edith Formation; however, the Edith Formation moderately consolidated deposits of light reddish- could also possibly mark the base of the aggrading brown, pale-brown to yellowish-brown gravel, sand, Los Duranes fluvial succession. and minor sandy clay derived from the ancestral Rio Grande and tributary streams. The base typically Menaul Formation(?) buried by deposits of the Rio Grande floodplain (Los Padillas Formation) in the Albuquerque. The basal The Menaul Formation of Lambert (1968) is contact forms a low-relief strath approximately 20 ft generally less than 10 ft (3 m) thick and overlies (6 m) above the Rio Grande floodplain near interfingering piedmont deposits that overlie the Bernalillo, New Mexico (Figs. 3-4), where the Los Edith Formation. The Menaul Formation consists of Duranes Formation is eroded by numerous arroyos poorly consolidated deposits of yellowish-brown and is about 20-23 ft (6-7 m) thick. The basal contact pebble gravel and pebbly sand derived from the is approximately 100 ft (30 m) lower than the base of ancestral Rio Grande. Rounded quartzite pebbles that the Edith Formation. The terrace tread on top of the are generally smaller in size than pebbles and cobbles Los Duranes Formation (~42-48 m above the Rio in the Edith Formation. The Menaul gravel forms Grande) is about 12-32 m higher than the top of the discontinuous, lensoidal exposures along the eastern Edith Formation. Geologic mapping and comparison margin o the Rio Grande valley. The basal contact is of subsurface data indicate that the base of the Edith approximately 85-118 ft (26-36 m) above the Rio Formation is about 20-25 m higher than the base of Grande floodplain. The Menaul Formation is Los Duranes Formation, suggesting that the Los conformably overlain by younger, eastern-margin Duranes is inset against the Edith. Just north of piedmont alluvium exhibiting Stage II+ carbonate Bernalillo, New Mexico, deposits correlated to the morphology, and is inset by younger stream alluvium Los Duranes Formation (Connell, 1998) contain the that exhibits weakly developed soils, suggesting a Rancholabrean mammal Bison latifrons (Smartt et late Pleistocene age of deposition. al., 1991, SW1/4, NE1/4, Section 19, T13N, R4E), Soils on piedmont deposits overlying the which supports a middle Pleistocene age. The Los Menaul are generally similar to the Los Duranes Duranes Formation is also overlain by the 98-110 ka Formation; however, differences in parent material Cat Hills basalt (Maldonado et al., 1999), and locally texture make soil-based correlations somewhat buries flows of the 156±20 ka (Peate et al., 1996) ambiguous. Similarities in height above the Rio Albuquerque volcanoes basalt. Thus deposition of the Grande and soil development on the Los Duranes Los Duranes Formation ended between 160-100 ka, Formation and the Menaul Formation suggest that near the end of the marine oxygen isotope stage 6 at these two units may be correlative. Thus, the Menaul about 128 ka (Morrison, 1991). Formation may be temporally correlative to the Los Near Bernalillo, the basal contact of the Los Duranes Formation, and is likely a member of this Duranes(?) Formation, exposed along the western unit. These units may be associated with an margin of the of the Rio Grande valley, is aggradational episode, possibly associated with approximately 30 m lower than the basal contact of aggradation of the Los Duranes, middle Pleistocene the Edith Formation, which is well exposed along the piedmont alluvium. The Edith Formation may eastern margin of the valley. This western valley- represent the base of a Los Duranes-Menaul margin fluvial deposit was originally assigned to the aggradational episode during the late-middle Edith Formation by Smartt et al. (1991), however, Pleistocene. The base Edith Formation is consistently these are interpreted to be younger inset deposits that higher than the base of the Los Duranes Formation, are likely correlative to the Los Duranes Formation suggesting that the Edith is older; however, definitive (Connell, 1998; Connell and Wells, 1999). crosscutting relationships have not been demonstrated.

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Figure 4. Simplified geologic cross sections across the Rio Grande valley, illustrating inset relationships among progressively lower fluvial deposits. Letters indicate location of profiles on Figure 1 and elevations of cross sections are in feet above mean sea level. See Table 1 for description of symbols. Unit QTs denotes upper Santa Fe Group deposits.

J-72 NMBMMR OFR 454B Rio Grande systems tract of the Sierra Ladrones Formation (Connell, 1997, 1998; Connell et al., 1995; Maldonado et al., 1999; Smith and Kuhle, 1998). The top comprises the modern floodplain and channel of the Rio Grande. The Los Padillas Formation is 15-29 m thick and consists of unconsolidated to poorly consolidated, pale-brown, fine- to coarse-grained sand and rounded gravel with subordinate, discontinuous, lensoidal interbeds of fine-grained sand, silt, and clay derived from the Rio Grande. This unit is recognized in drillholes and named for deposits underlying the broad inner valley floodplain near the community of Los Padillas in SW Albuquerque (Connell et al., 1998; Connell and Love, 2000). Drillhole data indicate that the Los Padillas Formation commonly has a gravelly base and unconformably overlies the Arroyo Ojito Formation. This basal contact is locally cemented Figure 5. Stratigraphic fence of Edith Formation and with calcium carbonate. The Los Padillas Formation piedmont deposits exposed along eastern margin of is overlain, and interfingers with, late Pleistocene to the Rio Grande valley, between Sandia Wash and Holocene valley border alluvial deposits derived highway NM-165, illustrating stratigraphic from major tributary drainages. relationships among fluvial-terrace and piedmont Because this unit has not been entrenched by the deposits. Rio Grande, no age direct constraints are available for the base of the alluvium of the inner valley in the Arenal Formation study area. This deposit underlies a continuous and relatively broad valley floor that extends south from The lowest preserved terrace deposit is the the Albuquerque basin through southern New Arenal Formation, which was named for exposures Mexico, where radiocarbon dates indicate just west of the Arenal Main Canal in SW aggradation of the inner valley by early Holocene Albuquerque (Connell et al., 1998). The Arenal time (Hawley and Kottlowski, 1969; Hawley et al., Formation is 3-6 m thick and is inset against the Los 1976). The base of the Los Padillas Formation was Duranes Formation. The Arenal Formation consists probably cut during the last glacial maximum, which of poorly consolidated deposits of very pale-brown to is constrained at ~15-22 ka in the neighboring yellow sandy pebble to cobble gravel recognized Estancia basin, just east of the Manzano Mountains. along the northwestern margin of the Rio Grande (Allen and Anderson, 2000). Thus, the inner valley inner valley. Gravel clasts are primarily rounded alluvium was probably incised during the latest quartzite and subrounded volcanic rocks (welded tuff Pleistocene and aggraded during much of Holocene and rare pumice) with minor granite. Soil time. Near the mouth of Tijeras Arroyo, charcoal was development is very weak, with Stage I to II+ recovered from about 2-3 m below the top of a valley carbonate morphology (Machette et al., 1997; border fan that prograded across the Los Padillas Machette, 1985). The top of the Arenal Formation is Formation and forms a broad valley border fan than the primero alto surface of Lambert (1968), which is has pushed the modern Rio Grande to the western 15-21 m above the Rio Grande. This deposit is not edge of its modern (inner) valley. This sample correlative to the Edith Formation as originally yielded a radiocarbon date of about 4550 yrs. BP interpreted by Lambert. This unit is interpreted to (Connell et al., 1998), which constrains the bulk of have been deposited during late Pleistocene time, deposition of the Los Padillas Formation to middle probably between about 71-28 ka. Holocene and earlier.

Los Padillas Formation EVOLUTION OF THE RIO GRANDE VALLEY

The Las Padillas Formation underlies the modern Santa Fe Group basin-fill deposits of the Rio Grande valley and floodplain and is interpreted ancestral Rio Grande generally differ in the scale and to represent the latest incision/aggradation phase of thickness relative to younger inset deposits, which the Rio Grande, which was probably deposited were deposited in well defined valley. During during latest Pleistocene-Holocene time. The Rio widespread aggradation of the basin (Santa Fe Group Grande floodplain (inner valley) ranges 3-8 km in time), the ancestral Rio Grande intimately width in most places and occupies only a portion of interfingered with piedmont deposits derived from the 10-12 km maximum width of the entire ancestral rift-margin uplifts, such as the Sandia Mountains

J-73 NMBMMR OFR 454B (Connell and Wells, 1999; Maldonado et al., 1999). by about 7 m down to the west near Bernalillo Field and age relationships in the near Santa Ana (Connell, 1996). Between cross sections B-B’ and C- Mesa also indicate that the ancestral Rio Grande also C’ of Figure 4, the basal contact of the Edith interfingered with fluvial deposits correlated with the Formation is down-dropped to the south by about 15 Arroyo Ojito Formation (Cather and Connell, 1998). m by the northwest-trending Alameda structural During development of the Rio Grande valley (post- zone. This decrease in height above local base level Santa Fe Group time), the Rio Grande cut deeply into is also recognized by a change in stratigraphic older basin-fill, typically leaving large buttress positions relative to piedmont deposits to the east. unconformities between inset deposits and older Younger piedmont alluvium (Qay, Fig. 2) is typically basin fill of the upper Santa Fe Group (Fig. 8). found overlying the Edith Formation south of the Younger late Pleistocene-Holocene alluvial Alameda structural zone (East Heights fault zone), a deposits are commonly confined in arroyo channels zone of flexure or normal faults that displace the cut into older piedmont deposits east of the Rio Edith Formation in a down-to-the-southwest sense. Grande valley. These deposits commonly form valley North of the Alameda zone, tributary stream deposits border alluvial fans along bluffs cut by a meandering are inset against the Edith Formation and are found in Rio Grande. These fans commonly prograde across well defined valleys (see map by Connell, 1997). floodplain and channel deposits in the inner valley. The present discharge is inadequate to transport sediment out of the valley. The presence of progressively inset fluvial deposits along the margins of the modern valley indicates that episodes of prolonged higher discharge were necessary to flush sediment and erode the valley. Such episodes must have occurred prior to aggradation of valley fills, such as these fluvial terrace deposits. Progradation of middle Holocene tributary valley border fans across the modern Rio Grande floodplain suggests that deposition of tributary and piedmont facies occurred during drier (interglacial) conditions. Deposition of fluvial terraces in semi-arid regions probably occurred during the transition from wetter to drier climates (Schumm, 1965; Bull, 1991). The lack of strong soils between the terrace deposits of the ancestral Rio Grande and piedmont and valley border deposits suggests that piedmont and valley border deposition occurred soon after the development of major fluvial terrace deposits. Age constraints for the Los Duranes Formation indicate that aggradation of fluvial deposits occurred near the end of glacial periods. If we extrapolate ages based on this model of terrace development, then we can provide at least a first order approximation for Figure 6. Correlation of fluvial deposits inferred ages of other poorly dated terrace deposits throughout ages. The age of the top of the Los Duranes the study area (Fig. 6). The age of the Edith Formation is constrained by middle and late Formation is still rather poorly constrained. The Pleistocene basalt flows. The Lomatas Negras Edith Formation is Rancholabrean in age and older Formation contains the middle Pleistocene Lava than the Los Duranes Formation, suggesting that the Creek B ash. The Edith Formation contains middle- Edith may have been deposited sometime during late Pleistocene Rancholabrean fossils and is older MOIS 8, 10, or 12. The lack of strongly developed than the Los Duranes Formation, however, its precise soils on the top of the Edith Formation suggests that age is not well constrained. Younger deposits are deposition of this unit occurred closer in time to the constrained by a radiocarbon date of 4550 yr. BP. Los Duranes Formation. The Edith Formation is interpreted to be older than Correlation of these deposits and provisional age the Los Duranes Formation and precise than the constraints indicate that the ancestral positions of the Lomatas Negras Formation. More precise age control Rio Grande have been modified by tectonic activity has not been established and the Edith Formation (Fig. 7). Most notably, the Edith Formation, which could have been deposited during different climatic forms a nearly continuous outcrop band from episodes. Albuquerque just south of San Felipe, New Mexico, is faulted. The Bernalillo fault displaced this deposit

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Figure 7. Generalized cross section across part of the piedmont of the Sandia Mountains, illustrating interfingering relationships among aggrading sediments of the upper Santa Fe Group, and inset post-Santa Fe Group deposits. Pedogenic carbonate morphology of constructional deposit surfaces is indicated by roman numerals that indicate the morphogenetic stage of soil development.

Figure 8. Longitudinal profile along Rio Grande, illustrating inset relationships among ancestral Rio Grande terraces and early Pleistocene aged constructional surfaces that locally mark the end of Santa Fe Group deposition (Las Huertas and Sunport geomorphic surfaces). The Edith and Los Duranes formations are deformed by northwest- trending faults that alter the elevation of the basal contact of these two units.

During late Pliocene time, the ancestral Rio and basin-fill of the Santa Fe Group. These episodes Grande formed an axial-river that flowed within a of entrenchment were followed by periods of partial few kilometers of the western front of the Sandia backfilling of the valley and progradation of Mountains (Fig. 9a). During early Pleistocene time, piedmont and valley border deposits (Figs. 9c and between about 1.3-0.7 Ma, the Rio Grande began to 9d). The latest episode of entrenchment and partial entrench into the basin fill, just west of the modern backfilling occurred during the latest Pleistocene, valley. Piedmont deposits prograded across much of when middle Pleistocene tributary deposits were the piedmont-slope of the Sandia Mountains and abandoned during entrenchment, and valleys partially buried these basin-fill fluvial deposits (Fig. 9b). aggraded later during latest Pleistocene and Holocene During middle Pleistocene time, the Rio Grande time (Fig. 9e). episodically entrenched into older terrace deposits

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Figure 9. Paleogeographic maps of the latest phase of basin filling of the Santa Fe Group, and Pleistocene development of the Rio Grande valley (modified from Connell, 1996). Las Huertas Creek (LHC), Pino Canyon (PC), and del Agua Canyon (dAC) are shown for reference.

REFERENCES County, New Mexico: New Mexico Bureau of Mines and Mineral Resources, Open-File Digital Allen, B.D., and Anderson, R.Y., 2000, A Geologic Map 19, scale 1:24,000. continuous, high-resolution record of late Chamberlin, R.M., Jackson, P., Connell, S.D., Pleistocene climate variability from the Estancia Heynekamp, M., and Hawley, J.W., 1999, Field Basin, New Mexico: Geological Society of logs of borehole drilled for nested piezometers, America Bulletin, v. 112, n. 9, p. 1444-1458. Sierra Vista West Park Site: New Mexico Bryan, K., 1909, Geology of the vicinity of Bureau of Mines and Mineral Resources Open- Albuquerque: University of New Mexico, File Report 444B, 30 p. Bulletin No. 3, 24 p. Connell, S.D., 1996, Quaternary geology and Bull, W.B., 1991, Geomorphic responses to climate geomorphology of the Sandia Mountains changes: New York, Oxford University Press, piedmont, Bernalillo and Sandoval Counties, 326 p. central New Mexico: New Mexico Bureau of Cather, S.M., and Connell, S.D., 1998, Geology of Mines and Mineral Resources Open-File Report the San Felipe 7.5-minute quadrangle, Sandoval 425, 414 p., 3 pls.

J-76 NMBMMR OFR 454B Connell, S.D., 1997, Geology of the Alameda 7.5- Albuquerque piezometer nests, Hunters Ridge minute quadrangle, Bernalillo County, New Park, May 1996: New Mexico Bureau of Mines Mexico: New Mexico Bureau of Mines and and Mineral Resources, Open-File Report 426C, Mineral Resources, Open-File Digital Geologic 25 p., 1 log, 1 fig. Map 10, scale 1:24,000. Johnson, P.S., Connell, S.D., Allred, B., and Allen, Connell, S.D., 1998, Geology of the Bernalillo 7.5- B.D., 1996, Field logs of boreholes for City of minute quadrangle, Sandoval County, New Albuquerque piezometer nests, West Bluff Park, Mexico: New Mexico Bureau of Mines and July 1996: New Mexico Bureau of Mines and Mineral Resources, Open-File Digital Geologic Mineral Resources, Open-File Report 426D, 19 Map 16, scale 1:24,000. p., 1 log, 1 fig. Connell, S.D., and Love, D.W., 2000, Stratigraphy of Kelley, V. C. and Kudo, A. M., 1978, Volcanoes and Rio Grande terrace deposits between San Felipe related basaltic rocks of the Albuquerque-Belen Pueblo and Los Lunas, Albuquerque Basin, New Basin, New Mexico: New Mexico Bureau Mines Mexico [abstract]: New Mexico Geology, v. 22, Mineral Resources, Circular 156, 30 p. n. 2, p. 49. Lambert, P.W., 1968, Quaternary stratigraphy of the Connell, S.D., and Wells, S.G., 1999, Pliocene and Albuquerque area, New Mexico: [Ph.D. Quaternary stratigraphy, soils, and dissertation] Albuquerque, University of New geomorphology of the northern flank of the Mexico, 329 p. Sandia Mountains, Albuquerque Basin, Rio Love, D. W., 1997, Geology of the Isleta 7.5-minute Grande rift, New Mexico: New Mexico quadrangle, Bernalillo and Valencia Counties, Geological Society, Guidebook 50, p. 379-391. New Mexico: New Mexico Bureau of Mines and Connell, S.D., and 10 others, 1995, Geology of the Mineral Resources, Open-file Digital Geologic Placitas 7.5-minute quadrangle, Sandoval Map 13, scale 1:24,000. County, New Mexico: New Mexico Bureau of Love, D., Maldonado, F., Hallett, B., Panter, K., Mines and Mineral Resources, Open-File Digital Reynolds, C., McIntosh, W., Dunbar, N., 1998, Map 2, scale 1:12,000 and 1:24,000, revised Geology of the Dalies 7.5-minute quadrangle, Sept. 9, 1999. Valencia County, New Mexico: New Mexico Connell, S.D., Allen, B.D., Hawley, J.W., and Bureau of Mines and Mineral Resources, Open- Shroba, R., 1998, Geology of the Albuquerque file Digital Geologic Map 21, scale 1:24,000. West 7.5-minute quadrangle, Bernalillo County, Lucas, S.G., Williamson, T.E., and Sobus, J., 1988, New Mexico: New Mexico Bureau of Mines and Late Pleistocene (Rancholabrean) mammals Mineral Resources, Open-File Digital Geologic from the Edith Formation, Albuquerque, New Map 17, scale 1:24,000. Mexico: The New Mexico Journal of Science, v. Dethier, D.P., 1999, Quaternary evolution of the Rio 28, n. 1, p. 51-58. Grande near Cochiti Lake, northern Santo Machette, M.N., 1985, Calcic soils of the Domingo basin, New Mexico: New Mexico southwestern United States: Geological Society Geological Society, Guidebook 50, p. 371-378. of America, Special Paper 203, p. 1-42. Gile, L. H., Peterson, F. F. and Grossman, R. B., Machette, M.N., Long, T., Bachman, G.O., and 1966, Morphological and genetic sequences of Timbel, N.R., 1997, Laboratory data for calcic carbonate accumulation in desert soils: Soil soils in central New Mexico: Background Science, v. 101, n. 5, p. 347-360. information for mapping Quaternary deposits in Hawley, J. W., 1996, Hydrogeologic framework of the Albuquerque Basin: New Mexico Bureau of potential recharge areas in the Albuquerque Mines and Mineral Resources, Circular 205, 63 Basin, central New Mexico: New Mexico Bureau p. of Mines and Mineral Resources, Open-file Maldonado, F., Connell, S.D., Love, D.W., Grauch, Report 402 D, Chapter 1, 68 p. V.J.S., Slate, J.L., McIntosh, W.C., Jackson, Hawley, J.W. and Kottlowski, F.E., 1969, Quaternary P.B., and Byers, F.M., Jr., 1999, Neogene geology of the south-central New Mexico border geology of the Isleta Reservation and vicinity, region: New Mexico Bureau of Mines and Albuquerque Basin, New Mexico: New Mexico Mineral Resources, Circular 104, p. 89-115. Geological Society Guidebook 50, p. 175-188. Hawley, J.W., Bachman, G.O. and Manley, K., 1976, Peate, D.W., Chen, J.H., Wasserburg, G.J., and Quaternary stratigraphy in the Basin and Range Papanastassiou, D.A., 1996, 238U-230Th dating of and Great Plains provinces, New Mexico and a geomagnetic excursion in Quaternary basalts of western Texas; in Mahaney, W.C., ed., the Albuquerque volcanoes field, New Mexico Quaternary stratigraphy of North America: (USA): Geophysical Research Letters, v. 23, n. Stroudsburg, PA, Dowden, Hutchinson, and 17, p. 2271-2274. Ross, Inc., p. 235-274. Personius, S. F., Machette, M. N., and Stone, B. D., Johnson, P.S., Connell, S.D., Allred, B., and Allen, 2000, Preliminary geologic map of the Loma B.D., 1996, Field logs of boreholes for City of Machette quadrangle, Sandoval County, New

J-77 NMBMMR OFR 454B Mexico: U.S. Geological Survey, Miscellaneous Smith, G.A. and Kuhle, A.J., 1998, Geology of the Field Investigations, MF-2334, scale 1:24,000, Santo Domingo Pueblo 7.5-minute quadrangle, ver. 1.0. Sandoval County, New Mexico, New Mexico Schumm, S.A., 1965, Quaternary paleohydrology, in Bureau of Mines and Mineral Resources, Open- Wright, H.E., and Frey, D.G., eds, The file Digital Geologic Map 15, scale 1:24,000. Quaternary of the United States: New Jersey, Princeton University Press, p. 783-794.

J-78 PRELIMINARY INTERPRETATION OF CENOZOIC STRATA IN THE TAMARA NO. 1-Y WELL, SANDOVAL COUNTY, NORTH-CENTRAL NEW MEXICO

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

DANIEL J. KONING 14193 Henderson Dr., Rancho Cucamonga, California 91739

NATHALIE N. DERRICK Department of Earth and Environmental Science, New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801

INTRODUCTION northwestern Albuquerque Basin. This area has been mapped in detail (Fig. 1) and provides additional The Tamara #1-Y well (API 30-043-20934) is a stratigraphic control for this well. wildcat oil-test that was drilled in northwest of Rio Rancho, New Mexico (Sec. 3, T13N. R2E., Table 1. Recalculated detrital mode parameters, Bernalillo NW quadrangle; UTM: N: 3,916,580 m, E: normalized to percent, of point counts (Appendix 1) 344,615 m, Zone 13, NAD83) in 1995 by Davis for medium-grained sand from the Tamara well using Petroleum Co. The Tamara well was spudded into the the modified Gazzi-Dickinson method (Dickinson, Ceja Member (upper Arroyo Ojito Formation of 1970). Volcanic grains comprise nearly all of the Connell et al., 1999), near the northern edge of the lithic parameters. Units are the Cerro Conejo (Tzc) Llano de Albuquerque, at an elevation of about 1865 and undivided Chamisa Mesa-Piedra Parada (Tzm) m (6120 ft) above mean sea level. The well was members of the Zia Formation, unit A and B, and drilled between December 1, 1995 and January 16, Galisteo Formation (Tg). The Galisteo Formation 1996. According to the scout ticket, the well stopped contains volcanic grains, probably from in the Triassic Chinle Group at a depth of 8723 ft contamination by caving of upper volcanic-bearing (2659 m) below land surface (bls); however, this units. correlation was not confirmed in this study. Washed cuttings from this well are archived at Interval Unit Modified Gazzi- the New Mexico Bureau of Mines and Mineral ft, bls Dickinson Method Resources (NMBMMR Library #46,891), in Socorro, %Q %F %L New Mexico. The well was cased to 329 m bls and 1390-1420 Tzc 68 18 15 cuttings were collected below 360 m bls; a number of 2620-2650 Tzm 67 17 16 intervals were not sampled, probably due to loss of 3970-4000 B 64 22 15 circulation during drilling. Cuttings were visually 4150-4180 B 72 18 10 evaluated using a sample preparation microscope on 5020-5050 A 68 19 14 available intervals between 360 and 2015 m bls. 5230-5260 A 70 19 11 Detrital modes of sand were determined on medium- 5290-5320 Tg 63 25 12 grained sand (400 points per sample) at eight sample 5410-5440 Tg 67 21 12 intervals in the Cenozoic section (Appendix 1) and normalized to the modified Gazzi-Dickinson method Another purpose in studying the Tamara well (Table 1). was to document the presence of older or pre-Santa Borehole geophysical logs, archived at the Fe Group Cenozoic strata near the basin margin, such NMBMMR, are available below 2103 m (6900 ft) as the Abiquiu, Popotosa, or Tanos formations, or the bls. Digital borehole geophysical logs of natural unit of Isleta #2. The Abiquiu Formation contains gamma ray and induction resistivity of the entire well mostly epiclastic sediments derived from the rhyolitic were obtained from the Denver Earth Resources Latir volcanic field in northern New Mexico (Smith, Library and the U.S. Geological Survey. 1995; Moore, 2000). Much of the Abiquiu Formation The Tamara well was spudded into the Santa Fe was deposited between ca. 18-27 Ma (Moore, 2000; Group near its local top on the Llano de Tedford and Barghoorn, 1993) and is temporally Albuquerque, near La Ceja (Rincones de Zia of correlative to the Piedra Parada and Chamisa Mesa Galusha, 1966; and Tedford, 1981) and fully members of the Zia Formation (Fig. 2). The penetrated the Cenozoic section, thus providing an southernmost mapped location of the Abiquiu opportunity to document variations in thickness of Formation is near the town of Gilman, New Mexico, the Santa Fe Group across intrabasinal faults of the K-79 NMBMMR OFR 454B

Figure 1. Generalized geologic map of the northwestern margin of the Calabacillas sub-basin (Albuquerque Basin), modified from the Cerro Conejo, Bernalillo NW, Loma Machette, and Bernalillo quadrangles (Connell, 1998; Koning and Personius, in review; Koning et al., 1998; and Personius et al., 2000). Stratigraphic study sites include Arroyo Piedra Parada (PP), Arroyo Ojito (AO), Zia fault (ZS), and the Marillo-Zia (MZ) sections. Unit QTu includes the Ceja Member of the Arroyo Ojito Formation of Connell et al. (1999). The Ceja Member unconformably overlies the Navajo Draw Member (not shown) on the footwall of the San Ysidro fault, but overlies the Loma Barbon Member to the east. Fossil localities of Galusha (1966; Tedford, 1981) indicated by black diamonds include the: Sanding Rock Quarry (SRQ; late Arikareean, 19-22 Ma), Rincon Quarry (RQ; late Barstovian, 12-14 Ma) and Zia Prospect (ZP; late Barstovian, 12-14 Ma). Volcanic ashes in the upper Cerro Conejo Member are correlated to the middle to late Miocene Trapper Creek tephra (Personius et al., 2000; Koning and Personius, in review). Water- supply and oil-test wells include the Tamara well (T#1Y), Santa Fe Pacific #1 (SFP#1), Rio Rancho Utilities #15 and #18 (RRU#15 and RRU#18, respectively). about 40 km north of the drill site (Duchene et al., is at least 15 Ma in the Belen sub-basin to the south 1981). Other temporally correlative units to the (Lozinsky, 1994) and may be as old as ca. 25 Ma in Abiquiu and Zia formations include the Tanos and the Abbe Springs basin, west of Socorro, New Blackshare formations, exposed in the Hagan Mexico (Osburn and Chapin, 1983). embayment, along the eastern margin of the The Zia Formation (Galusha, 1966) comprises Albuquerque Basin. The Tanos Formation is as old as the basal part of the lower Santa Fe Group in the 25.4 Ma (Connell and Cather, this volume) and Calabacillas sub-basin (Fig. 2). The Zia Formation is contains volcanic-bearing sediments derived from the dominated by eolian sandstone; fluviatile sandstone Ortiz Mts., along the eastern rift margin in the Hagan and mudstone beds tend to become more common embayment. To the south are exposed of the upsection. The Zia Formation has been subdivided Popotosa Formation. The Popotosa Formation is a into the Piedra Parada, Chamisa Mesa, Cañada thick succession of mudstone and sandstone unit that Pilares, and Cerro Conejo members (Galusha, 1966;

K-80 NMBMMR OFR 454B Gawne, 1981; Connell et al., 1999). The Piedra The Arroyo Ojito Formation (Connell et al., Parada Member unconformably overlies the pre-rift 1999) overlies the Zia Formation and is locally Galisteo Formation (Eocene) and Menefee Formation subdivided into three member units, in descending (Cretaceous). The age of the lower Piedra Parada stratigraphic order: the Ceja, Loma Barbon, and Member is constrained by mammalian fossils at Navajo Draw members. These units contain sand, Standing Rock quarry (Fig. 1; Galusha, 1966), which gravel, and mud deposits by S-SE flowing rivers indicate a late Arikareean North American land during late Miocene, Pliocene, and earliest mammal “age.” Correlations of these fossils to well Pleistocene times (Connell et al., 1999). dated localities in the Great Plains indicate an age of The unit of Isleta #2 (late Eocene-Oligocene) 19-22 Ma (Tedford and Barghoorn, 1999), although was proposed by Lozinsky (1988, 1994) for a 2 km the biostratigraphy of the Standing Rock quarry thick succession of purplish-red to gray volcanic- suggests an age of ca. 19 Ma (R.H. Tedford, 2000, bearing sandstone and mudstone recognized in deep written commun.). oil test wells 25-30 km to the south; however, it is not exposed in the basin. The sand is arkose, lithic arkose, and subarkose (Lozinsky, 1994). This unit is temporally correlative to Oligocene volcanic and volcaniclastic units of the Espinaso Formation, Mogollon-Datil volcanic field, and San Juan volcanic field.

LITHOLOGY OF THE TAMARA #1-Y WELL

Cenozoic sediments examined in the Tamara well are predominantly fine- to coarse-grained sand with interbedded mud and sparse fine gravelly sand. Sand composition ranges from subarkose, lithic arkose, and feldspathic arenite. The stratigraphy of the upper part of the Tamara well is constrained by excellent exposures of the Arroyo Ojito and Zia Formations along the southern margin of the Rio Jemez valley that have been mapped by Koning (Koning and Personius, in review; Koning et al., 1998; Connell et al., 1999). Geologic mapping (Koning and Personius, in review; Koning et al., 1998; Connell et al., 1999; Personius et al., 2000) indicates that neighboring strata of the Arroyo Ojito and Zia Formations generally dip about 3-10ºSW. A dip-meter log of strata below 2103 m (6900 ft) bls indicates that Cretaceous rocks dip as much as 20ºSW; however, it is not known whether stratal tilts in the upper part of the drillhole section progressively increase downhole, or whether they increase across unconformities. The thickness of Zia and Arroyo Ojito Formations were trigonometrically corrected using a 7º dip because of similar stratal tilts in exposures to the north. Deposit thickness was adjusted for 7º and 20º dips in lower Figure 2. Correlation chart of selected Santa Fe units (Appendix 2). Lag times are not known for the Group units in the northwestern Calabacillas and samples and may contribute up to several meters of Chama sub-basins (Connell et al., 1999; Tedford and error in estimating stratigraphic boundaries, probably Barghoorn, 1993; Moore, 2000; Lozinsky, 1994), and resulting in a slight increase in estimating apparent the Hagen embayment (Connell and Cather, this unit thickness. Dip-adjusted thickness of deposits volume). Triangles denote dates (in Ma) of primary correlated to the Zia and Arroyo Ojito Formations in volcanic units. Shaded boxes denote basaltic flows. the Tamara well is about 1138 m (Appendix 2). This Abbreviations include, Lobato basalt (Lob. bas.), Ojo is slightly thicker than estimates of about 1060 m for Caliente Member of the Tesuque Formation (OCM), a composite Santa Fe Group section exposed to the and Pedernal chert Member of the Abiquiu Formation west on the footwalls of the Zia and San Ysidro faults (PCM). North American Land Mammal “Ages” (Connell et al., 1999), and is considerably thicker (NMLMA). than the 410 m of Zia section exposed on the footwall

K-81 NMBMMR OFR 454B of the Sand Hill fault (Tedford and Barghoorn, 1999), and Personius, in review; Koning et al., 1998). At near the structural boundary of the basin. 405-424 m (1330-1390 ft) bls, traces of a gray altered tephra are recognized. This tephra-rich zone is in a similar stratigraphic position relative to ashes recognized in the upper part of the Cerro Conejo Member of the Zia Formation (usage of Connell et al., 1999) on the Bernalillo NW and Loma Machette quadrangles (Koning and Personius, in review; Personius et al., 2000). Some of these exposed ashes have been geochemically correlated to some of the middle to late Miocene (ca. 11-10 Ma) Trapper Creek tephra from Idaho (Personius et al., 2000; A. Sarna- Wojcicki, written commun., 2001; N. Dunbar, 2001, written commun., 2001). The lower part of the Cerro Conejo Member contains fossils that indicate a middle Miocene age (Tedford, 1981; Tedford and Barghoorn, 1999). The Cerro Conejo Member is 369- m thick in the Tamara well. The base of this unit is gradational with a 393-m thick succession of generally very pale brown to light gray, medium- to coarse-grained, subrounded to rounded, quartz-rich sandstone with abundant frosted quartz grains. This thick unit is correlated to the Chamisa Mesa and Piedra Parada members of the Zia Formation. The Zia Formation is composed of lithic arkose to feldspathic arenite (Beckner, 1996) and cemented zones are commonly recognized in this interval (Beckner and Mozley, 1998; Mozley and Davis, 1996). The basal 0.5-3 m of the Zia section exposed in Arroyo Piedra Parada contains fluviatile gravel composed mostly of rounded chert pebbles derived from the Galisteo Formation with scattered cobbles of rounded, intermediate volcanic rocks (Fig. 4) deposited by southeast-flowing streams (Gawne, 1981). Elsewhere, these cobbles form a discontinuous stone pavement, where many of the volcanic clasts Figure 3. Interpreted stratigraphic column of have been sculpted by the wind into ventifacts Cenozoic sediments for the Tamara #1-Y well, (Tedford and Barghoorn, 1999; Gawne, 1981). including natural gamma ray (GR) and electrical Volcanic clasts have been 40Ar/39Ar dated between 32 conductivity logs (calculated from induction to 33 Ma (three dates: 31.8±1.8 Ma, 33.03±0.02 Ma, resistivity log) for comparison purposes. 33.24±0.24 Ma; S.M. Cather, W.C. McIntosh, Stratigraphic interpretations are based on evaluation unpubl. data), indicating that they were once part of of cuttings and projection of contacts from geologic the subjacent middle Tertiary volcaniclastic mapping. succession. These deposits unconformably rest upon upper Eocene sandstone and mudstone of the upper Projections of mapped contacts on the Bernalillo Galisteo Formation (Lucas, 1982). Thus, this gravel- NW quadrangle (Koning and Personius, in review) bearing interval represents an unconformity that indicate that the base of the Loma Barbon Member of probably ranges between about 10-14 m.y. in the Arroyo Ojito Formation is at 183 to 378 m bls duration between the Galisteo and Zia Formations at (Fig. 3). Deposits correlated to the Ceja Member crop the northwestern margin of the Albuquerque Basin. out along the northern rim of the Llano de Between 1146-1393 m bls is unit B, an interval Albuquerque (La Ceja) and are 30-85 m in thickness, of pink to very pale-brown, mostly fine- to medium- of which ~15 m are penetrated in this well (Koning grained, quartz-rich feldspathic arenite and lithic and Personius, in review; Personius et al., 2000). At arkose recognized below strata correlated to the about 180 m bls, deposits of very pale brown, fine-to Piedra Parada Member in the Tamara well. Traces of medium-grained, quartz-rich sand are correlated to a white ash and sparse scattered volcanic grains are the Navajo Draw Member on the basis on observed between 1283-1292 m (4210-4240 ft) and comparisons with nearby geologic mapping (Koning 1366-1375 m (4480-4510 ft) bls, respectively. The

K-82 NMBMMR OFR 454B lower 27 m of this interval contains trace amounts of purplish-gray intermediate volcanic rocks. The stratigraphic position of this unit, below the Piedra Parada Member, suggests that it might be correlative to the Abiquiu Formation. Petrographic analysis of this interval indicates that the Cenozoic portion of the Tamara well is distinct from the Abiquiu Formation, which contains considerably less quartz than Cenozoic deposits studied in the Tamara well (Fig. 5).

K-83 GUIDE TO THE GEOLOGY OF THE EASTERN SIDE OF THE RIO GRANDE VALLEY ALONG SOUTHBOUND I-25 FROM RIO BRAVO BOULEVARD TO BOSQUE FARMS, BERNALILLO AND VALENCIA COUNTIES, NEW MEXICO

DAVID W. LOVE, S.D. CONNELL, N. DUNBAR, W.C. MCINTOSH, W.C. MCKEE, A.G. MATHIS, and P.B. JACKSON-PAUL New Mexico Bureau of Mines and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

J. SORRELL, and N. ABEITA Pueblo of Isleta, P.O. Box 1270, Isleta, NM 87022

INTRODUCTION (a) local volcanoes disrupt the fluvial systems, (b) water and sediment discharge change through time The Plio-Pleistocene geology of exposures east for all of the fluvial and alluvial systems (perennial of the Rio Grande floodplain to the top of the Sunport and ephemeral streams), (c) stream gradients change surface and equivalent surfaces from Rio Bravo due to local tectonic perturbations, (d) some uplifted Boulevard southward to Bosque Farms looks blocks are beveled by a laterally swinging and deceptively simple from a distance, but is complex at aggrading combined axial stream, and (e) piedmont local outcrop scale. We interpret the exposures of the deposits interfinger with axial stream deposits along uppermost Santa Fe Group (Arroyo Ojito and Sierra the margin of the active half graben (Fig. 8). Ladrones Fms) along the Rio Grande Valley from Rio Bravo Boulevard in Albuquerque, south to Isleta Pueblo, Bosque Farms, and Los Lunas, New Mexico, using several basic geological concepts pertinent to rift basins. The first concept (1) relates the fill of a half graben to a combination of an axial river and lengthy hanging wall tributaries and short footwall fans that are transverse to the axial river (Leeder and Gawthorpe, 1987; Fig. 1). The second concept (2) is that normal faults in the northern Albuquerque basin change scarp-face direction (Chamberlin, 1999; Fig. 2). The third concept (3) combines the first two, as a Figure 1. Axial stream in a half graben. Note short half-graben axial stream slaloms back and forth, footwall fans and longer tributaries descending the following the changing position of the lowest points hanging wall. among half-graben basins and sub-basins (Fig. 3). The fourth concept (4) is that of fluvial fans, which are fluvial deposits that spread laterally and longitudinally along a basin floor from a large feeder trunk stream, typically developed on hanging walls, not from the shorter transverse streamflow-dominated piedmont deposits derived from footwall uplifts along the eastern basin margin (Love and Seager, 1996; Fig. 4). The fifth concept (5) is that of spillovers as fluvial systems extend fluvial fans into adjacent basins (Mack et al., 1997; Fig. 5). The sixth concept (6) combines concepts of fluvial fans and spillovers to a basin where three fluvial systems compete for axial position along a major half graben, but two of the fans enter the basin from the broad hanging wall (Fig. 6). The seventh concept (7) is the breakup the simple half-graben with an axial-fluvial system and large hanging-wall tributaries (concept 1) into a series of smaller sub-parallel half grabens influenced by changes in fault-dip polarity across Figure 2. Block diagram showing steep fault with intrabasinal normal faults (Fig. 7). Finally, real world alternating scarps and null points along it. complications make geology less simple (8) wherein

L-89 NMBMMR OFR 454B GEOLOGY AND GEOMORPHOLOGY OF caldera that formed soon after caldera collapse and THE ISLETA AREA emplacement of the UBT. The breakout flood likely swept through the Jemez River canyon, picked up If these concepts are to be applied to the geology boulders of Tertiary basalts and Precambrian of the Isleta area, the scale of the concepts must crystalline rocks, and spread out across the Sunport match local conditions. Applying concept 1 (the axial surface. The Rio Grande reworked these flood stream in a half graben with broad hanging wall) to deposits shortly after this flood and prior to this area, the major half-graben fault in Plio- entrenchment of the present valley. A water- Pleistocene time is the Hubbell Spring fault zone, 13 reworked fine-grained ash from within the upper part km east of the west edge of the Sunport surface. The of the section yielded sanidine crystals with peaks in axial-fluvial systems tract of the early Pleistocene the age spectra from 1.05 to 1.7 Ma; however, the ancestral Rio Grande is also about 13 km wide younger age is associated with fairly low beneath the Sunport and Llano de Manzano surfaces. concentrations of potassium, which suggests that part The hanging wall with tributaries extended ~ 26-32 of this ash was altered. Thus, this 1.05 Ma date is too km east from the valley of the Rio Puerco to the axial young. An ash bed, recognized below the Sunport ancestral Rio Grande near the latitude of southern surface along the southern margin of Tijeras Arroyo, Albuquerque. These fluvial fans had headwaters yielded a 40Ar/39Ar date of 1.26±0.02 Ma, which is beyond the hanging wall and crossed the basin consistent with an upper Bandelier Tuff age. A diagonally from the north and northwest extending fluvial terrace deposit of the ancestral Rio Grande 48-161 km north-south. They deposited sediments west of the Rio Grande is lower than the Sunport, over hundreds of square km up-gradient from the suggesting that it is inset against the Sunport surface. axial Rio Grande. High sediment delivery to the basin This terrace deposit contains a fluvially recycled ash from the major tributaries probably overwhelmed that has been chemically correlated to the ca. 0.60- small tectonic disruptions on the hanging wall. 0.66 Ma Lava Creek B ash from the Yellowstone hotspot in Wyoming. These two tephra constrain the age of the Sunport surface to between 1.2-0.6 Ma. Paleomagnetic studies of fine-grained deposits near the local top of the section, between Hell Canyon Wash and Tijeras Arroyo, are pending.

Figure 3. Block diagram illustrating axial stream that slaloms between half grabens along alternating- scarp fault blocks.

Working downsection from the Sunport surface, at the top of the exposures beneath eolian sheet sands and a strong stage III to local stage IV calcic soil are sand and gravel of the ancestral Rio Grande. This >10-m thick gravelly sand is a mixture of resistant, well-rounded clasts of extrabasinal origin that include boulders (up to 4 m in diameter) of upper Bandelier Tuff (UBT, 1.22 Ma). Also included are locally preserved Tschirege Ash (1.22 Ma; see below), pebbles of Tewa-Group pumice and obsidian from the Jemez Mountains (beginning with the 1.8-Ma San Diego Canyon Ignimbrite; cf. Self et al., 1996). The Figure 4. Fluvial fans of the Rio Mimbres system boulders were probably deposited as a result of a (from Love and Seager, 1996). Note that the breakout flood from a breached lake in the Valles Mimbres fluvial system is already out in a basin before it spreads into fan shapes.

L-90 NMBMMR OFR 454B well, 6.5 km southeast of the Rio Bravo interchange, at least 500 m of fluvial sediments were penetrated. Valley-margin exposures between Tijeras Canyon and Hell Canyon are cut by three major, and numerous minor faults in a north-northwest-trending zone called the Palace-Pipeline fault zone. Two of the major faults are normal, down to the west. The third is down to the east. There are hints of strike-slip motion as well, but no definitive piercing points to demonstrate horizontal movement. Minor faults are subparallel to this zone, but tend to bend to the east or west. Although the topographic relief of the present valley is about 130 m, the total exposed stratigraphic section is more than 135 m thick because of faulting and local stratal tilts. Beds dip as much as 7ºSE; apparent dips along the outcrop belt are roughly 1º to the south. The southeastward tilt has preserved the middle and upper parts of the stratigraphic section above that seen on the highest block and below the youngest fluvial deposits of the Sunport surface (Fig. 10). The highest exposed structural block is stripped of at least 73 m of section seen on other blocks. Critical stratigraphic markers for the Plio-Pleistocene section include <5 cm-thick basaltic tephra geochemically correlated to Isleta volcano (2.7-2.8 Figure 5. Spillover fluvial systems in different Ma), Hawaiite tephra (unknown age), fluvially basinal situations (from Mack et al., 1997). Mimbres recycled Pliocene pumice and Bandelier Tuff, and type (A), where the fluvial system enters and flows thick (~24 m) reddish-brown clay, silty clay, and fine through the basin nearly parallel to the footwall scarp sand. and axial valley. Columbus type (B), in which the fluvial system flows down the hanging wall dip slope of the spillover basin and builds a fluvial fan perpendicular to the footwall scarp. Tularosa type (C), in which the fluvial system moves across the footwall scarp into the spillover basin and builds a fluvial fan on the hanging wall dip slope perpendicular to the basin axis.

The axial Rio Grande deposits associated with the Sunport surface and Llano de Manzano are cut by numerous normal faults with separation of up to 15 m (Fig. 9). This faulted surface is partially buried by a piedmont alluvial apron prograding west from the Manzanita and Manzano Mountains. Beneath the upper 10 m of sediment, the valley- margin geology is complicated. Locally, ancestral Rio Grande fluvial deposits, containing Tewa-Group pumice and obsidian, extend 30 m below the Sunport surface where they rest upon Pliocene deposits of the Arroyo Ojito Formation. Biostratigraphic data indicate the presence of a disconformity between the Figure 6. Schematic half-graben basin with axial Arroyo Ojito Fm and pumice-bearing fluvial deposits fluvial system and two fluvial fans (ff1 and ff2) of the Sierra Ladrones Formation. To the south, near descending the hanging wall. Isleta Pueblo, this disconformity is more pronounced and occurs within 10 m of the Sunport surface, where At the southern end of the exposures (Fig. 10), it is an angular unconformity. Ancestral Rio Grande about 20 m of section is exposed between the top of deposits tend to thicken to the east, where they are the axial gravel and an exposure of lower(?) exposed in the walls of both Tijeras Canyon and Hell Bandelier ash that has been dated at about 1.55 Ma. Canyon. At a monitoring well drilled on Mesa del Sol L-91 NMBMMR OFR 454B An 40Ar/39Ar date on this ash sampled north of Hell (Connell et al., 1999). From Rio Bravo Boulevard Canyon was interpreted to include crystals of the 1.05 south, the units include volcanic clasts from both the Ma Valles dome rhyolite (Love et al., 2001), but western side of the Jemez Mountains (paleo-Jemez these crystals have been recently reinterpreted to be River to the north) and clasts from the Rio Puerco fluvially reworked Bandelier ash (N. Dunbar and W. (coming into the Albuquerque basin from the McIntosh, personal commun., 2001). Beneath this northwest). Both types of deposits were spread across ash north of Hell Canyon is about 30 m of cross- the northern Albuquerque basin as low-gradient bedded, pumice-bearing, loose pebbly sand of the fluvial fans that interfingered with each other. ancestral Rio Grande. Beneath them are pale, Reworked, water-rounded pumice from Jemez cemented, fine-grained deposits that indicate a high eruptions spread laterally at least 24 km east-west, local water table (spring-related or krenegenic and at least 113 km north-south. These fluvial fans deposits). Below these deposits are 24 m of fine- descended southeastward to join the axial Rio grained reddish-brown beds and 49 m of Grande, which was the axial stream along the crossbedded, planar-bedded sand, and cross-bedded Hubbell Spring fault zone. The presence of relatively pebbly-to-cobbly sand. The sandy units locally monolithologic pumice-bearing units 113 km south include at least 4 different pumice-bearing beds. of their source in the Jemez Mountains suggests that Below is basaltic tephra correlated to the eruptions of these streams may have followed local alternating the Isleta tuff ring, base surge, lava flows and other half-graben sub-basins (west of here, closer to Wind cinder eruptions. These tephra are found on at least Mesa). The reddish-brown marker unit with spring- four different structural blocks at various elevations. related units at the top, followed by deposition of Maximum offset across at least two faults is about ancestral Rio Grande along the Isleta valley-border 100 m. transect, may signal a rearrangement of the structure of the hanging-wall and a subsequent adjustment of the northern and western fluvial fans.

Figure 7. Block diagram showing the breakup of the half-graben hanging wall into several segments and the underlying stratigraphy resulting from fluvial fans and axial system of Figure 6.

Continuing downward in the section, beneath the Isleta tephra on the central uplifted block are another Figure 8. Block diagram showing complications of 21 m of cross-bedded pebbly sand, sand, and silty- lateral erosion of axial stream across fault blocks, clay planar beds. Locally, at least two more pumice- buried volcano, and advancement of piedmont across bearing beds crop out below the Isleta tephra. part of floodplain. North of Isleta, beneath Mesa del Sol are Pliocene sections exposed on uplifted fault blocks. Exposures in Tijeras and Hell Canyons as well One measured section includes 17 m of concretionary as along the Rio Grande Valley near Isleta show that sandstone, silt, and clay with a 3-cm thick Hawaiite more than 30 m of axial Rio Grande sand and gravel ash beneath coarser crossbedded loose sand. Another aggraded before the stream shifted westward. It 35-m section has a pumice bed at its base that beveled and buried at least two uplifted fault blocks, correlates geochemically to a pumice bed beneath received breakout flood debris from the Jemez River, Los Lunas Volcano to the southwest and Rio Rancho and finally began to entrench the present valley west to the northwest. This pumice bed is in the same part of its former course (Fig. 10). of the section at Los Lunas volcano that contains an Across the valley southwest of this stop are 40Ar/39Ar-dated 3.12 Ma pumice (Maldonado et al., Black Mesa and Isleta volcano, two Pliocene basaltic 1999). eruptive units with 40Ar/39Ar dates ranging from 2.7 The Pliocene crossbedded sandstones, pebbly to 2.8 Ma (Maldonado et al., 1999). In erosional sandstones, pumice and basaltic tephra-bearing contact with, above, and inset below the basalts, are sandstones beneath the thick reddish-brown fine- several levels of inset terrace deposits. The highest grained marker are part of a thick, laterally extensive terrace is 79 m above the Rio Grande. In the gravel package of transverse fluvial deposits. This package, pit north of the Black Mesa basalt flow is an deposited by major western-margin rivers and exposure of Lava Creek B ash, about 46 m above the streams, is called the Arroyo Ojito Formation river.

L-92 NMBMMR OFR 454B Neogene Age, northwestern Albuquerque Basin, Rio Grande rift, New Mexico: Geological Society of America, Abstracts with Programs, v. 31, no. 7, p. A-113. Connell, S.D., Koning, D.J., and Cather, S.M., 1999, Revisions to the stratigraphic nomenclature of the Santa Fe Group, northwestern Albuquerque Basin, New Mexico: New Mexico Geological Society, Guidebook 50, p. 337-353. Leeder, M. R., and Gawthorpe, R. L., 1987, Sedimentary models for extensional tilt- block/half-graben basins, in Coward, M. P., Dewey, J. F., and Hancock, P. L, eds, Continental Extensional Tectonics: Geological Society of London, Special Publication 28, p. 139-152. Love, D.W., Connell, S.D., Chamberlin, R.M., Cather, S.M., McIntosh, W.C., Dunbar, N., Smith, G.A., Lucas, S.G., 2001, Constraints on the age of extensive fluvial facies of the upper Santa Fe Group, Albuquerque and Socorro basins, central New Mexico: Figure 9. Digital elevation model of Sunport surface Geological Society of America, Abstracts between Tijeras Canyon and Hell Canyon showing with Programs, v. 33, n. 5, p. A48. faulted blocks and encroachment of piedmont from Love, D. W., and Seager, W. R., 1996, Fluvial fans east. and related basin deposits of the Mimbres drainage: New Mexico Geology, v. 18, p. 81-92. Love, D.W., Dunbar, N., McIntosh, W.C., McKee, C., Connell, S.D., Jackson-Paul, P.B., and Sorrell, J., 2001, Late Miocene to Early Pleistocene geologic history of Isleta and Figure 10. Schematic north-south sketch of about 18 Hubbell Spring quadrangles based on ages km of exposures of Santa Fe-Group sediments from and geochemical correlation of local and Rio Bravo Boulevard (I-25, exit 220) to bluffs east of Regional volcanic rocks [abs]: New Mexico Bosque Farms, New Mexico. Geology, v. 23, p. 55. Mack, G. H., Love, D. W., and Seager, W. R., 1997, ACKNOWLEDGEMENTS Spillover models for axial rivers in regions of continental extension: the Rio Mimbres This study was funded in part by the New and Rio Grande in the southern Rio Grande Mexico Statemap Program of the National rift, USA: Sedimentology, v. 44, p. 637-652. Cooperative Geologic Mapping Act (P.W. Bauer, Maldonado, F, Connell, S. D., Love, D. W., Grauch, Program Manager) and the New Mexico Bureau of V. J. S., Slate, J. L., McIntosh, W. C., Mines and Mineral Resources (P.A. Scholle, Jackson, P. B., and Byers, F. M. Jr., 1999, Director). We thank the Pueblo of Isleta for Neogene geology of the Isleta Reservation graciously allowing access onto tribal lands during and vicinity, Albuquerque basin, New this study. We also thank Florian Maldonado (U.S. Mexico: New Mexico Geological Society Geological Survey) for his considerable help and Guidebook 50, p. 175-188. advice on the geology and stratigraphy of western Self, S., Heiken, G., Sykes, M. L., Wohlets, K., part of Isleta Pueblo. Fisher, R. V., and Dethier, D. P., 1996, Field excursions to the Jemez Mountains, New REFERENCES Mexico: New Mexico Bureau of Mines and Mineral Resources, Bulletin 134, 72 p. Chamberlin R. M., 1999, Partitioning of dextral slip in an incipient transverse shear zone of

L-93 TH FRIENDS OF THE PLEISTOCENE, ROCKY MOUNTAIN-CELL, 45 FIELD CONFERENCE

PLIO-PLEISTOCENE STRATIGRAPHY AND GEOMORPHOLOGY OF THE CENTRAL PART OF THE ALBUQUERQUE BASIN

OCTOBER 12-14, 2001

SEAN D. CONNELL New Mexico Bureau of Geology and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

DAVID W. LOVE New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

JOHN D. SORRELL Tribal Hydrologist, Pueblo of Isleta, P.O. Box 1270, Isleta, NM 87022

J. BRUCE J. HARRISON Dept. of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801

Open-File Report 454C and D Initial Release: October 11, 2001

New Mexico Bureau of Geology and Mineral Resources New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801 NMBGMR OFR454 C & D

INTRODUCTION

This field-guide accompanies the 45th annual Rocky Mountain Cell of the Friends of the Pleistocene (FOP), held at Isleta Lakes, New Mexico. The Friends of the Pleistocene is an informal gathering of Quaternary geologists, geomorphologists, and pedologists who meet annually in the field. The field guide has been separated into two parts. Part C (open-file report 454C) contains the three-days of road logs and stop descriptions. Part D (open-file report 454D) contains a collection of mini-papers relevant to field-trip stops. This field guide is a companion to open-file report 454A and 454B, which accompanied a field trip for the annual meeting of the Rocky Mountain/South Central Section of the Geological Society of America, held in Albuquerque in late April. Errors in compiling this field-excursion are undoubtable. Please kindly inform the authors of any errors or omissions. We appologize for any unintended omissions or citations. In keeping with the informal character of Rocky Mountain Cell FOP field excursions, this guidebook contains preliminary findings of a number of concurrent projects being worked on by the trip leaders. Thus, this guidebook should be considered as a type of progress report on geologic mapping, stratigraphic work, and radioisotopic dating. The contents of the road logs and mini-papers have been placed on open file in order to make them available to the public as soon as possible. Revision of these papers is likely because of the on-going nature of work in the region. The papers have not been edited or reviewed according to New Mexico Bureau of Geology and Mineral Resources standards. The contents of this report should not be considered final and complete until published by the New Mexico Bureau of Geology and Mineral Resources. Comments on papers in this open-file report are welcome and should be made to authors. The views and preliminary conclusions contained in this report are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the State of New Mexico, Pueblo of Isleta, or the U.S. Government.

ACKNOWLEDGEMENTS

The New Mexico Bureau of Geology and Mineral Resources (P.A. Scholle, Director) supported this field trip. Much of the data presented during this field trip are from numerous open-file reports released by the New Mexico Bureau of Geology and Mineral Resources during the course of cooperative geologic mapping with the U.S. Geological Survey (New Mexico Statemap Project, P.W. Bauer, Program Manager). We are particularly grateful to the people of the Pueblo of Isleta for granting access during many of the stratigraphic and mapping studies discussed during the field trip. In particular, we thank the Honorable Alvino Lucero, Governor of Isleta, for granting access to study stratigraphically significant sites on the reservation. We are indebted to Florian Maldonado for his help and important work on the western part of the Isleta Reservation. Bill McIntosh and Nelia Dunbar provided the many important dates and tephrochronologic correlations in the Albuquerque Basin. We are grateful to John Hawley, Steven Cather, Dan Koning, and Richard Chamberlin for their assistance and advice. We thank Tien Grauch, Dirk Van Hart, and Keith Kelson for freely sharing their ideas on the geology and structure of the Isleta Reservation and Sandia National Laboratories area. In particular, the site- wide hydrologic project at Sandia National Laboratories conducted by GRAM Inc. and William Lettis and Associates (Thomas et al., 1995) was especially helpful in documenting the geology of Kirtland Air Force Base and the Sandia Labs. We also thank Jim Cole and Byron Stone for sharing some of their ideas on the late-stage development of the basin. David McCraw and Patricia Jackson-Paul assisted in the field and in the preparation of some of the map and poster figures. Leo Gabaldon assisted with drafting of the simplified geologic map of the Isleta Reservation. Glen Jones and Mark Mansell produced the shaded-relief images from 10-m DEM data released by the U.S. Geological Survey.

ii NMBGMR OFR454 C & D

GUIDEBOOK TABLE OF CONTENTS OPEN-FILE REPORT 454C

First Day Road Log: Geology of the Isleta Reservation S.D. Connell, D. W. Love, and J.D. Sorrell...... 1-1

Second Day Road Log: Geology of southern Albuquerque and Tijeras Arroyo S.D. Connell, D.W. Love, J.B.J. Harrison...... 2-1

Third Day Road Log: Geology of Los Lunas volcano D.W. Love, W.C. McIntosh, N. Dunbar, and S.D. Connell ...... 3-1

MINI-PAPER TABLE OF CONTENTS OPEN-FILE REPORT 454D

Terraces of Hell Canyon and its tributaries, Memorial Draw and Ojo de la Cabra D. W. Love ...... A-1

Surface geology and liquefaction susceptibility in the inner valley of the Rio Grande near Albuquerque, New Mexico K.I. Kelson, C.S. Hitchcock, and C.E. Randolph ...... B-1

Stratigraphy of middle and upper Pleistocene fluvial deposits of the Rio Grande Valley (Post-Santa Fe Group) and the geomorphic development of the Rio Grande Valley, northern Albuquerque Basin, central New Mexico S.D. Connell and D. W. Love ...... C-1

Summary of Blancan and Irvingtonian (Pliocene and early Pleistocene) mammalian biochronology of New Mexico (reprinted from NMBMMR Open-file report 454B) G.S. Morgan, and S.G. Lucas ...... D-1

Plio-Pleistocene mammalian biostratigraphy and biochronology at Tijeras Arroyo, Bernalillo County, New Mexico (reprinted from NMBMMR Open-file report 454B) G.S. Morgan and S.G. Lucas ...... E-1

Cuspate-lobate folds along a sedimentary contact, Los Lunas volcano, New Mexico (reprinted from NMBMMR Bulletin 137) W.C. Haneberg...... F-1

iii NMBGMR OFR454 C & D

Plate I. Shaded-relief map of the Isleta Reservation and southern Albuquerque field-trip area illustrating the locations of day 1 (black square), day 2 (black diamond), and day 3 (white diamond) stops. All trips start from the Isleta Lakes Campground (black circle) in the inner valley of the Rio Grande. The Llano de Albuquerque is a broad, south-sloping interfluve between the Rio Puerco and Rio Grande Valleys, which was formed during late Pliocene time. The hachured lines indicate the approximate boundary of inset fluvial terrace deposits of the Rio Grande Valley. The broad low-relief surfaces east of the Rio Grande Valley contain the Pleistocene Sunport (SP) and Llano de Manzano surfaces, and the Pliocene Cañada Colorada surface (CC). The approximate eastern and western limits of the axial-fluvial Rio Grande (a) is denoted depicted by white dotted lines. TC and HC indicate the mouths of Tijeras, and Hell Canyons, respectively. Nearly all of the north- and northwest-trending scarps are faults that cut these geomorphic surfaces. Base from shaded-relief image in Maldonado et al. (1999) and was prepared from 10-m DEM data from the National Elevation Database of the U.S. Geological Survey.

iv NMBGMR OFR454 C & D

Plate II. Simplified geologic map of the Albuquerque Basin (Connell, in preparation).

v NMBGMR OFR454 C & D

Plate III. Stratigraphic correlation diagrams of deposits in the central Albuquerque Basin and southern Jemez Mountains. Black triangles and circles denote radioisotopically dated primary, and fluvially recycled volcanic products, respectively. Bones denote biostratigraphically significant fossil mammal sites. Volcanic units are shaded. Dates are from various sources and noted in Ma. Deposits of Zia Fm include the Chamisa Mesa (C. Mesa) and Cañada Pilares (CPM) mbrs. Rancholabrean (RLB) and Irvingtonian (Irv) are Pleistocene divisions of the North American Land Mammal “ages.”

vi NMBMMR OFR 454C TH FRIENDS OF THE PLEISTOCENE, ROCKY MOUNTAIN CELL, 45 FIELD CONFERENCE

PLIO-PLEISTOCENE STRATIGRAPHY AND GEOMORPHOLOGY OF THE CENTRAL PART OF THE ALBUQUERQUE BASIN

FIRST-DAY ROAD LOG, OCTOBER 12, 2001

Geology of the Isleta Reservation

SEAN D. CONNELL New Mexico Bureau of Geology and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

DAVID W. LOVE New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

JOHN D. SORRELL Tribal Hydrologist, Pueblo of Isleta, P.O. Box 1270, Isleta, NM 87022

The following road log examines some of the many outstanding geologic and geomorphic features on the Isleta Reservation. The first day of this field excursion examines lower Pleistocene deposits of the ancestral Rio Grande, the axial-river of the Albuquerque Basin and the namesake of the Rio Grande rift, and interfingering deposits of the eastern-margin piedmont. We also examine the role of faulting on the preservation of early Pleistocene and Pliocene geomorphic surfaces along the eastern margin of the basin. The day-one trip will conclude with a traverse to the eastern slopes of the late Pleistocene Cat Hills volcanic field to a visit to a graben on the San Clemente land grant. This graben preserves a sequence of sand and mud that overlies a buried soil developed on upper Pliocene fluvial deposits associated with rivers that drained the western margin of the basin. Many of the dates cited here are from Maldonado et al. (1999) and from unpublished data of Bill McIntosh and Nelia Dunbar (NM Bureau of Geology and Mineral Resources). Nearly the entire following road log is on tribal lands administered by the Pueblo of Isleta, which are restricted to the public. Access to Pueblo lands must be made through the tribal administrator or governors office (Pueblo of Isleta, P.O. Box 1270, Isleta, New Mexico) prior to travelling on Pueblo lands. In respect for the privacy of the tribal community, we ask that you discuss access for geologic study or to access Pueblo lands to examine the exposures discussed herein with John Sorrell, Dave Love, or Sean Connell, prior to contacting the Governor’s Office for permission. Road-log mileage has not been checked for accuracy. Field-trip stops illustrated on Plate I.

Mi. Description deposits. Fluvial deposits from the proto-Rio 0.0 Begin trip at south side of store at the Isleta Grande and Rio Puerco systems probably Lakes Campground, Isleta 7.5’ quadrangle emptied into the northern and northwestern (1991), GPS: NAD 83, UTM Zone 013 S, N: parts of the basin before these river systems 3,867,855 m; E: 346,955 m. (Note that the integrated south into southern New Mexico UTM ticks on this quad are incorrect). Drive during latest Miocene (?) or early Pliocene east and leave Isleta Lakes Campground. 0.3 time. The upper sub-group represents 0.3 Railroad Crossing. 0.1 deposition within externally drained 0.4 Isleta Eagle Golf Course to south, a 27-hole (hydrologically open) basins where the Rio course operated by the tribe and is part of Grande represents the through-going axial their growing resort complex. 0.1 river and contains a generally consistent 0.5 Exposures of Arroyo Ojito Fm in bluffs to pattern of lithofacies assemblages. Within south. Basin-fill deposits are assigned to the externally drained half-graben basins, axial- upper Oligocene to lower Pleistocene Santa fluvial deposits are bounded on either side Fe Group, which comprises the synrift by deposits derived from the footwall and volcanic and sedimentary rocks of the Rio hanging walls of the basin (Fig. 1-1). Grande rift. The Santa Fe Group is Hanging-wall deposits typically comprise commonly subdivided into a lower subgroup the bulk of deposition, both spatially and representing deposition within internally areally. Axial-river deposits interfinger with drained (hydrologically closed) basins piedmont deposits derived from rift-flank containing playa-lake, eolian, and piedmont uplifts, such as the prominent chain of

1-1 NMBMMR OFR 454C mountains of the Sandia-Manzanita- Deposits of the axial-fluvial ancestral Manzano-Los Pinos uplifts along the eastern Rio Grande are provisionally assigned to the rift border, and the Ladron Mountains to the Sierra Ladrones Fm of Machette (1978) as southwest. In the Albuquerque area, upper are also locally derived deposits of the Santa Fe Group deposits are three major eastern margin that interfinger with these lithofacies assemblages that represent extrabasinal fluvial sediments. The Sierra distinctive depositional systems. The most Ladrones Fm has been extended from its abundant (both spatially and volumetrically) type area at the southern edge of the basin, are deposits of the Arroyo Ojito Fm, which about 65 km to the south, by a number of is a middle Miocene to Pliocene (and workers (Hawley, 1978; Lucas et al., 1993; possibly earliest Pleistocene) fluvial Smith et al., 2001), however, the succession associated with major western stratigraphic and lithologic relationship tributaries to the axial Rio Grande, such as between these deposits and those of the type the Rio Puerco, Rio Jemez/Guadalupe, and area is ambiguous. The Sierra Ladrones Fm Rio San Jose systems (Fig. 1-2). These was defined without a type section and age western rivers joined deposits of the control is generally poor in the type area. ancestral Rio Grande just east of the present Studies of the type area of the Sierra Rio Grande Valley during late Pliocene Ladrones Fm (Connell et al., 2001a) are time. The present-day confluence of the Rio underway and results of this study should Puerco and Rio Grande is just south of aid in its correlation throughout the basin. Bernardo, New Mexico, about 55 km south 0.1 of Isleta, New Mexico

Figure 1-1. Diagram illustrating the distribution of sediments in a half-graben during deposition of the upper Santa Fe sub-Group (modified from Mack and Seager, 1990). This figure depicts the spatial distribution of major fluvial components. The axial-river is bounded on either side by deposits derived from the footwall and hanging wall of the half graben. This diagram represents a “post orogenic” stage of basin development where footwall-derived deposits prograde basinward during times of relative tectonic quiescence (see Blair and Bilodeau, 1988).

1-2 NMBMMR OFR 454C Palace-Pipeline fault zone. This zone may be responsible for the presence of H2S in groundwater in this area. 0.2 0.9 Turn right (south) onto highway NM-47 at the Conoco Gas Station and Convenience Store. 0.1 1.0 The upper Pliocene basaltic centers west of the Rio Grande Valley, include the 2.72- 2.79 Ma Isleta volcano at 2:00, and the 4.01 Ma Wind Mesa volcano at 2:00-3:00 (40Ar/39Ar dates summarized in Maldonado et al., 1999). Bluffs to the east are of the Arroyo Ojito Fm, overlain by a thin cap of ancestral Rio Grande deposits of the Sierra Ladrones Fm. The Arroyo Ojito Fm here contains base surge from Isleta volcano and fluvially recycled 2.75 Ma pumice. 0.2 1.2 Cross arroyo. Fault exposed to your right cuts the Arroyo Ojito Fm and younger alluvium, locally. 0.2 1.4 Milepost 40 and stop light. Isleta Casino and Resort to your left. 1.0 2.4 Milepost 39. Arroyo Ojito Fm in road cuts ahead. 0.5 2.9 Just west of the highway and near the level of the floodplain are exposures of the Arroyo Ojito Fm that contain fluvially recycled pumice dated at 2.68 Ma (40Ar/39Ar Figure 1-2. Schematic map showing the approximate date, W.C. McIntosh, unpubl.) and basaltic areal distribution of major lithofacies in Pliocene tephra (cinders) that were probably derived sediments of the upper Santa Fe Group (modified from 2.72-2.79 Ma Isleta volcano (Fig. 1-3). from Connell et al., 1999; Love et al., 2001). The The contact between ancestral Rio Grande south-flowing ancestral Rio Grande (ARG) is the and western-fluvial deposits of the Arroyo axial-fluvial facies (gray shading). The Arroyo Ojito Ojito Fm is unconformable here. At least 25- Fm (stippled pattern) represents deposition by a 68 m of the underlying Arroyo Ojito Fm is series of large S-SE-flowing tributary drainages missing here. 0.6 originating on the Colorado Plateau, San Juan Basin, 3.5 Merge into left lane. 0.4 Sierra Nacimiento, and western Jemez Mts. These 3.9 Turn left (east) at stop light at intersection deposits are associated with the ancestral Rio Puerco with NM-47 and SP-60/NM-147. Travel on (ARP), Rio Guadalupe/Jemez (AGJ), ancestral Rio Pueblo lands is restricted and permission San Jose (ARJ), and ancestral Rio Salado (ARS). must be obtained prior to entry. All tribal These fluvial deposits merge into a single axial- laws and customs must be obeyed on Pueblo fluvial system at the southern margin of the basin. lands. Permission to take photographs and The conglomerate pattern delineates locally derived samples must be obtained from tribal deposits from rift-margin uplifts. The Cochiti Fm officials. Please drive slow (<10 MPH) (light-gray shading) consists of volcanic-bearing through housing area. 0.4 sediments shed off the southeast flank of the Jemez 4.3 Cross cattle guard and ascend valley border. Mts. The boundaries among sub-drainages of the 0.5 Arroyo Ojito Fm are approximate and diagrammatic. 4.8 Exposures to south (right) are of the Isleta Sediment sources to deposits of the Albuquerque South Powerline stratigraphic section (Fig. Basin include sedimentary and chert (S), volcanic 1-4). The uppermost gray beds are pumice- (V), plutonic/metamorphic (P), and metaquartzite bearing deposits of the ancestral Rio (Q). Grande. Pumice pebbles and cobbles are fluvially recycled gravel of the Cerro Toledo 0.7 Two normal faults with down-to-the-east Rhyolite (1.6-1.2 Ma) and Bandelier Tuff displacement are exposed in Arroyo Ojito (1.2 and 1.6 Ma; Izett and Obradovich, Fm to north on eastern edge of borrow pit. 1994), which are early Pleistocene These faults are part of a wider zone ignimbrite sheets that were emplaced during included within the down-to-the-west the development of the Jemez Mountains, 1-3 NMBMMR OFR 454C about 80 km to the north. These deposits also contain pebbles to small cobbles of black obsidian, which has been geochemically correlated to the 1.43-1.52 Ma Rabbit Mountain obsidian of the Cerro Toledo Rhyolite (Stix et al., 1988). These deposits are part of the axial-fluvial facies of the Sierra Ladrones Fm, which forms a 10- 12-km wide axial ribbon that is typically exposed east of the present Rio Grande Valley. Deposits of the ancestral Rio Grande are recognized in drillholes within 2 km west of the front of the Sandia Mountains in the Northeast Heights section of Albuquerque and within 6 km of the Manzanita Mts. 0.3

Figure 1-3. Cross Section of eastern bluff of Rio Grande Valley, illustrating age and stratigraphic relationships between the upper Arroyo Ojito Fm (Tocl, Tocu) and Sierra Ladrones Fm (Qsa). Unit Tocu contains abundant mudstone and overlies the Figure 1-4. Stratigraphic column of the Isleta South sandstone dominated Tocl, which is similar to the Powerline composite section. Deposits of the Ceja Member of the Arroyo Ojito Fm. The amount of ancestral Rio Grande contain fluvially recycled eroded and faulted section on the east (right) side of pumice (P) from the upper and lower Bandelier Tuff this cross section are based on estimates of the (BT) and Rabbit Mountain obsidian (O) of the Cerro thickness of the sediment between the 2.68 Ma tephra Toledo Rhyolite. Fallout ashes and fluvially recycled and the highest preserved part of unit Tocu. Primary pumice of the Cerro Toledo Rhyolite (1.55 Ma) and tephra indicated by open triangles, recycled pumice upper Bandelier Tuff (1.26 Ma, not shown here) are denoted by open circles. Hachures denote soils. also found near the top of this section. These deposits Roman numerals indicate pedogenic carbonate overlie a moderately cemented and morphologic stage. Dotted lines denote apparent dip rhizoconcretionary-bearing interval in the Arroyo of beds. Ojito Formation, however, no distinctive unconformity is recognized here. Elsewhere, most 5.1 Turn right onto two-track dirt road. 0.2 notably near faults, this contact is unconformable. 5.3 Intersection with two-track road. Continue Bedding dips slightly to the southeast. Hachures straight. 0.1 denote soils. Roman numerals indicate pedogenic carbonate morphologic stage.

1-4 NMBMMR OFR 454C 5.4 Ascend onto the Sunport surface, which is to-the-west normal movement. Isleta 7.5’ faulted by a number of down-to-the-west quadrangle, GPS: NAD 83, UTM Zone 013 faults. The Sunport surface is a S, N: 3,864,180 m; E: 348,495 m. constructional surface named by Lambert Light-gray, loose, sand and pebbly sand exposed (1968) for the Albuquerque International just beneath the broad mesa of the Sunport surface are Airport (a.k.a. Sunport) on the north side of correlated to axial-river deposits of the ancestral Rio Tijeras Arroyo. This surface is part of the Grande, which is provisionally assigned to the Sierra Llano de Manzano of Machette (1985). The Ladrones Fm. Gravelly intervals contain abundant Llano de Manzano was considered by rounded volcanic and metaquartzite cobbles and Machette (1985) to represent a surface that pebbles with minor granite. Chert is very sparse. graded to an alluvial terrace about 92-113 m Deposits of the ancestral Rio Grande unconformably above the modern Rio Grande. The Llano de overlie deposits of the Arroyo Ojito Fm along the Manzano is considerably lower than the eastern margin of the valley in the field-trip area (Fig. Llano de Albuquerque surface to the west, 1-4). Just north of this stop, this contact is slightly which is about 110-215 m above the modern angular near a series of north-trending normal faults of Rio Grande (Machette, 1985) and represents the Palace-Pipeline fault zone exposed along the the upper constructional surface of the eastern margin of the Rio Grande Valley. Gravel Arroyo Ojito Fm. Recent studies (Connell et contains scattered, fluvially recycled cobbles and rare al., 2000; Maldonado et al., 1999) indicate boulders of the 1.22 Ma upper Bandelier Tuff. Fallout that the Llano de Manzano is composed of a and fluvially reworked ashes are locally recognized in number of different geomorphic surfaces, these deposits and have been dated and geochemically rather than a single surface. We use correlated to the 1.2 Ma Bandelier Tuff and the 1.55 Lambert’s (1968) Sunport surface to Ma Cerro Toledo Rhyolite. Scattered rounded obsidian distinguish it from the slightly younger pebbles are also in this deposit. Some of these have Llano de Manzano surface complex to the been geochemically correlated to the 1.43-1.52 Ma south and east, which contains piedmont Rabbit Mountain obsidian (Stix et al., 1988) of the deposits that prograde across much of this Cerro Toledo Rhyolite. A mudstone containing aquatic abandoned fluvial surface. We concur with and terrestrial gastropods is locally preserved between Machette (1985) on the differences in age the loose sand and gravel and overlying fine-to and geomorphic position between the medium-grained eolian sand and petrocalcic soil of the Sunport/Llano de Manzano surfaces and the Sunport surface, which exhibits Stage III+ to locally Llano de Albuquerque. Stratigraphic and weak Stage IV pedogenic carbonate morphology (Fig. geomorphic data suggest that the Sunport 1-5). Cessation of deposition of the ancestral Rio and Llano de Albuquerque surfaces are Grande and development of the Sunport surface is about two to five times older than estimated constrained by deposits of the Lomatas Negras fm, by Machette (1985). During Day 1 and 2 which contains a fallout ash of the ~0.66 Ma Lava stops, we present evidence that the Sunport Creek B (Yellowstone National Park area, Wyoming and Llano de Manzano surfaces should be and Montana). This terrace deposit is topographically considered part of the basin-fill succession, lower than the Sunport surface, which contains a 1.26 rather than as inset deposits that are Ma ash in Tijeras Arroyo. These stratigraphic and stratigraphically disconnected from early geomorphic relationships demonstrate that the Sunport depositional events. surface developed between 0.7-1.2 Ma. This age is The Sunport surface contains a similar to ages of major erosional events reported for petrocalcic soil that exhibits Stage III+ the abandonment of the lower La Mesa geomorphic pedogenic carbonate morphology. Platy surface and subsequent entrenchment of the Rio structure is locally recognized in natural Grande in southern New Mexico (Mack et al., 1993, exposures, but a laminar carbonate horizon 1996), and for an unconformity between the St. David is only weakly developed in places. On the Fm and overlying alluvium in a tectonically quiescent basis of pedogenic carbonate development, basin in southeastern Arizona (Smith, 1994). The Machette (1985) originally estimated the age mudstone at the top of this section has been sampled of the Llano de Manzano surface to be about for paleomagnetic studies by John Geissman 300 ka. 40Ar/39Ar dates and geochemical (University of New Mexico) to better constrain the correlations on tephra inset against and timing of development of the Sunport surface. beneath the Sunport surface constrain the development of this constructional fluvial surface to between 1.2-0.7 Ma. 0.1 5.5 STOP 1-1. East edge of Rio Grande Valley and ancestral Rio Grande deposits. Stop near trace of northeast-trending fault with down-

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Figure 1-5. View looking north of Isleta South Powerline Section (Fig. 1-5) from footwall of northeast-trending normal fault. The white band at along the edge of exposures is the Sunport surface, which exhibits Stage III+ to locally weak Stage IV pedogenic carbonate morphology. Dave Love and 1.5-m scale on a snail-bearing mudstone bed preserved on hanging wall of unnamed northeast-trending fault. This mudstone pinches out at the left side of the photograph, near the lone juniper bush.

A major focus of this field trip is to document the These deposits have bounding disconformities along timing late-stage filling of the Albuquerque Basin and the base and margins. In particular, the margins of subsequent entrenchment and development of smaller such deposits are distinctive in their development of aggradational events associated with a long-term net buttress unconformities, which include buried decrease in local base level during Quaternary time. paleobluffs. During aggradation of the Santa Fe Group, regional A recent model of late-stage basin sedimentation base level, as controlled by the Rio Grande, would and entrenchment, based upon the work of Machette have been increasing with a concomitant rise in (1985) and Reneau and Dethier (1996), was proposed groundwater levels (Fig. 1-6) and local development by Cole (2001a, b) and Stone (2001a, b). This, of phreatic cements. Using conceptual models of termed herein as the Cole-Stone (CS) model for sedimentation in extensional basins (see summaries in convenience, proposes that widespread aggradation Leeder and Jackson, 1993; Gawthorpe and Leeder, of synrift basin filling ceased during late Pliocene 2000), axial-fluvial sedimentation would be focussed time, by about 2.5 Ma, when the ancestral Rio along active eastern basin margin faults and rift- Grande entrenched into older deposits of the upper margin piedmont deposits would be limited to a rather Santa Fe Group. They proposed that this late Pliocene narrow band near the eastern structural margin of the entrenchment created the constructional surface of basin. The axial-fluvial system flowed longitudinally, the Llano de Albuquerque, the interfluve between the whereas, hanging-wall deposits typically drained valleys of the Rio Puerco and Rio Grande. obliquely to the axial river. Deposits derived from the The CS model agrees with Machette’s (1985) footwall flowed in a transverse orientation relative to interpretation of the early Pleistocene deposits of the the axial river. Concomitant deposition and tectonic Sunport surface representing the oldest inset fluvial subsidence along the basin-bounding fault would terrace deposit in the basin (Stone et al., 2001a,b). result in the development of interfingering and wedge- This inset relationship is based on inferences shaped stratal packages. regarding the location of the paleo-groundwater table During entrenchment, the Rio Grande Valley using the spatial and temporal distributions of formed in a series of episodic entrenchment and partial phreatomagmatic and non-phreatomagmatic aggradation events. This net decline in base level eruptions in the region (Cole et al., 2001a), and in a would result in the removal of water in the aquifer. record of repeated entrenchment and aggradation Deposits associated with the development of incised events dating back to early Pliocene time in White valleys contain somewhat tabular fluvial successions Rock Canyon (Reneau and Dethier, 1996) at the of extrabasinal detritus. The margins of these deposits margin of the Española and Albuquerque basins, are bounded by locally derived alluvium from bluffs. about 80 km to the north (Fig. 1-7).

1-6 NMBMMR OFR 454C

Figure 1-6. Hypothetical stratigraphic relationships of sedimentation in an actively subsiding half-graben basin; intrabasinal faulting is not accounted for in this conceptual model. Intrabasinal faults can create local fault-wedge stratigraphic successions that would have similar stratal geometries to this model; however, deposition would be dominated by eolian and colluvial processes, rather than fluvial. Deposits from the hanging wall (Oblique systems tract; Arroyo Ojito Fm) are volumetrically the largest component of the basin fill. The axial-fluvial system (AST) occupies the central part of the basin and interfingers with OST and locally derived transverse deposits (TST) from the footwall uplift. During times of significant footwall upflift (or basin subsidence), AST and TST will be close to the uplifting footwall block (cf. Blair and Bilodeau, 1988). During times of relative tectonic quiescence or slower subsidence rates, TST will onlap onto AST and AST will onlap onto OST (cf. Blair and Bilodeau, 1988; Mack and Seager, 1990). Offlap and the development of sediment bypass surfaces on the OST could occur along the hanging- wall border because of the relative lack of space developed in this simple block rotational model. If the OST has been abandoned, then an unconformity between AST and OST will develop during westward onlap of AST onto older OST deposits as AST and TST progrades basinward. This interaction between deposition and subsidence in this simplified fault block results in the development of wedge-shaped stratal units and eastward thickening from the up-dip portion of the hanging wall (1) and the continually subsiding footwall (2). Offlap of the western-fluvial facies could occur as progressive rotation of the hanging wall creates subsidence along the footwall. This would likely result in the development of unconformities along the up-dip portions of the hanging wall. Progradation of axial- river and piedmont deposits could occur during onlap of these deposits onto the hanging wall surface of western- fluvial deposits, resulting in the development of a wedge of axial-river and piedmont deposits near the footwall. The hachured area denotes the development of an unconformity along the boundary between western fluvial deposits (oblique depositional systems tract, OST), and the axial-fluvial systems tract (AST) of the ancestral Rio Grande. Westward onlap of the AST would result in the preservation of an unconformity that would increase in magnitude towards the up-dip portion of the hanging wall. Continued deposition between the AST and the eastern piedmont (transverse systems tract, TST) would occur towards the footwall. B) Hypothetical diagram contrasting deposition in an aggrading basin (i.e., Santa Fe Group time) and episodic deposition during periods of long-term net entrenchment. During net aggradation, base level rises and facies interfinger with one another and deposits tend to have a wedge-shaped geometry and thicken towards the basin-bounding fault. During net entrenchment, base level fall and the upper parts of the basin fill system are drained of water. Episodic aggradational events are recorded as unconformity bounded tabular sedimentary units. Progressive net decline in base level and groundwater levels, which drained out of the upper part of the basin-fill aquifer. Dashed lines represent paleo-base level positions of the axial river.

1-7 NMBMMR OFR 454C

Basic elements, either explicitly required, or perched groundwater is present. Volcanic features reasonably inferred by the CS model include: bury and preserve paleo-topography, however, the • Development of phreatomagmatic relative stability a particular paleo-topographic volcanism during aggradational phase of surface (i.e., stable geomorphic surface, or just a basin because of near surface groundwater. preserved bed in an otherwise conformable • Lack of thick or extensive fluvial deposits stratigraphic sequence) can only be deduced with during a nearly 2 m.y. interval, between confidence where indicators of surface stability, such about 2.8-0.8 Ma. An exception is along the as soils, are present. La Bajada fault zone, which defines the Rates of Plio-Pleistocene fluvial deposition are Albuquerque- Española basin boundary. poorly constrained by are on the order of about 100 • Widespread hiatus in deposition indicates m/m.y. or less near San Felipe Pueblo (Derrick and that the drainage system had begun to erode Connell, unpubl. data). This rate is significantly into upper Santa Fe Group strata by 2.5 Ma. slower than rates of deposition of the Popotosa Fm • Oldest significant post-phreatomagmatic- (lower Santa Fe sub-Group), which were near 400 basalt fluvial deposits are preserved as a m/m.y. during late Miocene time (Lozinsky, 1994). terrace east of the Rio Grande Valley. Thus, rates of deposition slowed by Pliocene time, The model proposed by Connell et al. (2000; but deposition was occurring in the basin (see Smith 2001c) and Love et al. (2001) and modified herein, et al., 2001). suggests that: • Basin-fill aggradation occurred during Pliocene and Pleistocene changes in climate. Stratigraphic and subsurface studies (Connell et al., 1998a, 1999; Hawley et al., 1995) note that deposits become markedly coarser near the top of the Santa Fe Group. Incision of the Santa Fe Group occurred between 0.7-1.2 Ma here. This bracketed age is similar to well documented entrenchment events in the Camp Rice Fm (southern New Mexico correlative of the Sierra Ladrones Fm), suggesting that entrenchment was of a regional nature. • Late-stage deposition of the Santa Fe Group was strongly controlled by the activity and location of intrabasinal faults. This tectonic influence on sedimentation would be increased if sedimentation rates were slow, too. Figure 1-7. Graph depicting timing of major • Determination “normal” aggradational entrenchment and aggradation events in the southern stratigraphic successions vs. incised fluvial- Española Basin at White Rock Canyon (Reneau and terrace suites can be difficult, especially in Dethier, 1996), about 85 km north of Stop 1-1. The the Albuquerque Basin, where most of the black circles represent dated deposits and the basin-fill and post-basin-fill deposits are projected position of the ancestral Rio Grande. The lithologically similar. However, stratal dashed line represents projected levels of the geometries and unconformity development ancestral Rio Grande through time in White Rock can be useful tools in discriminating Canyon, which is on the footwall of the La Bajada between these two different depositional fault and has been strongly affected by repeated Plio- processes. Pleistocene volcanic events. Refer to Reneau and Landscape evolution can be inferred by Dethier (1996) for discussion of methods and dates. reconstructing pre-faulting positions, ages, and Deep incision occurred between about 3.65-2.33 Ma stratigraphic-geomorphic setting of volcanic deposits, in White Rock Canyon. This was followed by which are useful because they are resistant to erosion repeated aggradation and deep incision events and have reasonably predictable surface forms. In throughout late Pliocene and Pleistocene time. Note particular, topographic inversion of basaltic flows are that the Rio Grande was aggraded to 1970 m )and useful in determining the rate and magnitude of above its former position prior to ~3 Ma) after 1.2 valley entrenchment. However, care must be used Ma and before White Rock Canyon was entrenched. when inferring paleo-groundwater conditions because phreatomagmatic eruptions could occur where 1-8 NMBMMR OFR 454C In the Española Basin, Reneau and Dethier shed off of eastern margin uplifts and are buried by (1996) provide excellent evidence for repeated progradation of eastern-margin piedmont detritus. Pliocene and Pleistocene entrenchment events that Stratigraphic evidence along strands of the may be related to climatically and geomorphically Hubbell Spring fault zone shows early Pleistocene (e.g., volcanically and tectonically) driven incision. deposits of the ancestral Rio Grande are an integral Their study area is near the structural margin of the part of the basin-fill depositional system in an Española and Albuquerque basins and lies within a asymmetric or complexly faulted half-graben basin. geomorphically, volcanically, and tectonically active We argue that deposition of the Santa Fe Group area, where deposition and incision were strongly generally ceased when the Rio Grande unequivocally influenced by faulting and episodic damming of the entrenched into older fluvial deposits during early river valley. Here at Isleta, local unconformities are Pleistocene time, forming discontinuous flights of interpreted as the result of concurrent deposition and unpaired terrace deposits that border the Rio Grande tilting (Connell et al., 2001b) and local uplift of an Valley. Deposition of the Santa Fe group continued intrabasinal horst (Love et al., 2001). We suggest that locally into the Pleistocene, where smaller non- these apparently disparate controls on sedimentation integrated drainages deposited sediment onto broad influence the depositional system in different, but not abandoned plains and piedmont-slopes of the Llano mutually exclusive, manners. For instance, deposits de Manzano. Intrabasinal faulting and coeval of the upper Santa Fe Group generally coarsen sedimentation resulted in the formation of a number upwards (see Connell et al., 1998b). The of distinct geomorphic surfaces on local uplifted fault development of these coarsening upwards sequences blocks, resulting in the development of a number of in the uppermost Santa Fe Group demonstrate local tops of the basin fill. South of the Española increased competence of Plio-Pleistocene rivers and Basin, many workers generally consider the Santa Fe could be associated with an increase in effective Group basin-fill system to have aggraded until early moisture during Plio-Pleistocene times; however, Pleistocene time, when the Rio Grande Valley coarsening of piedmont deposits could also be formed (Smith et al., 2001; Connell and Wells, 1999; attributed to basinward progradation during times of Connell et al., 1998; Maldonado et al., 1999; Hawley tectonic quiescence (Leeder and Gawthorpe, 1987; et al., 1995). Blair and Bilodeau, 1988). Our interpretation of the stratigraphy has the The CS model differs from part of the model of distinct advantage of distinguishing basin-fill from Connell et al. (2000, 2001c), which suggests that younger entrenched deposits with less ambiguity that spatially time-transgressive sedimentation and the C-S model. The determination of hiatal surfaces development of local stratigraphic tops in the Santa along the eastern margin of the basin would be Fe Group occurred into Pleistocene time. This difficult, mainly because of the influence of faulting diachroneity of sedimentation is strongly influenced on sedimentation and because age control is generally by continued faulting and tilting in the basin during lacking for much of the sedimentary succession. late Pliocene and Pleistocene time, which resulted in Along the eastern margin of the Albuquerque Basin, the development of unconformities on the up-dip between Cochiti Pueblo and Hell Canyon Wash, portions of hanging wall blocks and concomitant exposures and drillhole data indicate the presence of aggradation near basin depocenters (Connell et al., conformable stratigraphic successions of Plio- 2001c). The presence of numerous scarps cutting Pleistocene age. The presence of soils locally marks Pleistocene deposits attests to continued deformation unconformities or hiatuses in the section. However, within the basin. This is supported by paleoseismic these would be rather difficult to extend across a studies of the basin that indicate Quaternary tectonically active basin. By picking a broader set of movement of intrabasinal faults between 2-20 m/m.y. criteria for basin-fill aggradation, these ambiguities (Machette et al., 1998; Personius et al., 1999; are diminished, especially in areas with little Personius, 1999; Wong et al., in prep). subsurface control or exposure. The CS model proposes that the Sunport surface Problems with reconciling these two models is represents the highest inset fluvial terrace deposit in important because the CS model requires the the Albuquerque Basin (Stone et al., 2001a,b). If this presence of a rather profound unconformity beneath interpretation is true, then this rather broad (5-10 km the eastern side of the basin to accommodate their wide) terrace deposit should be inset against older Sunport terrace. The removal of over 70 m of basin fill deposits along the eastern margin. Geologic Pliocene sediment would create a previously mapping of the Isleta Reservation to the northeastern unrecognized major hydrogeologic discontinuity in edge of the basin (Cather and Connell, 1998; Cather Albuquerque’s aquifer. The presence of such a et al., 2001; Connell and Wells, 1999; Maldonado et discontinuity would also significantly revise al., 1999; Smith et al., 2001) does not recognize such estimates of the amount of drawdown required for a buttress unconformity. Instead deposits of the irreversible subsidence, as was recently estimated by ancestral Rio Grande system interfinger with deposits Haneberg (1999).

1-9 NMBMMR OFR 454C Stratigraphic evidence amassed by Sean Connell projection on the basis of drillhole data on and Dave Love since 1997, indicates the presence of the Isleta Reservation and on two partial an intraformational unconformity between early lines of seismic reflection data and drillhole Pleistocene deposits of the ancestral Rio Grande and data that demonstrate the presence of a the Arroyo Ojito Formation on Isleta Pueblo and major intrabasinal graben beneath the Tijeras Arroyo. To the south, the unconformity present Rio Grande Valley (Fig. 1-8). between the Sierra Ladrones and Arroyo Ojito Gravity data (Grauch et al., 1999) and formations diminishes. A major unconformity within geologic studies of the basin (Maldonado et the ancestral Rio Grande is recognized locally al., 1999; Connell and Wells, 1999; Connell between deposits containing the Cerro Toledo ash et al., 1998) suggest that this intrabasinal and overlying coarse gravels of the Rio Grande north structure is likely an older feature that of the mouth of Hell Canyon Wash (see Day 2). This probably trended to the northwest rather unconformity is related to local faulting and than to the north (Maldonado et al., 1999). migration of the ancestral Rio Grande. This The presence of thick early Pleistocene unconformity may die out to the east. Such deposits on the footwall of the Rio Grande unconformable relationships are recognized in a few fault does not support the presence of areas, and thus may not be applicable in a regionally significant Pleistocene activity along this consistent manner without precise age constraints. fault. However, the presence of an Turn vehicles around and drive towards SP-60. 0.3 unconformity and intrabasinal faults 5.8 Hard right onto east-trending two-track road, exposed along the eastern margin of the Rio which rejoins SP-60 heading east. 0.2 Grande Valley at Stop 1 does support 6.0 Turn east onto SP-60. 0.4 significant late(?) Pliocene tectonism near 6.4 Ascend scarp of Palace-Pipeline fault, which the present day valley. 0.2 cuts deposits of the ancestral Rio Grande. 6.6 Cross cattle guard and descend broad east- The trace of the Palace-Pipeline fault, which tilted footwall block of Palace-Pipeline fault. is about 19-m high here, is named for its This block generally slopes towards west- proximity to the old Isleta Gaming Palace facing scarps of splays between the Palace- and a gas pipeline. This fault roughly Pipeline fault and the McCormick Ranch corresponds with the location of the Rio fault zone. The TransOcean Isleta #1 well, Grande fault of Russell and Snelson (1994) about 1.8 km to the north, was drilled to south of Albuquerque. Russell and Snelson 3163 m below land surface (bls) and (1994) proposed the Rio Grande fault as a encountered 1563 m of Santa Fe Group prominent intrabasinal normal fault that cut basin fill (Fig. 1-8; Lozinsky, 1994). The off the range-bounding normal faults of the Shell Isleta #2 well, drilled just west of Manzanita and Sandia Mountains after late Isleta volcano, was drilled to 6482 m bls and Miocene or Pliocene time (Russell and encountered 4407 m of Santa Fe Group Snelson, 1994). Russell and Snelson (1994) strata (Lozinsky, 1994). 0.6 projected their Rio Grande fault northward 7.2 Borrow pit on north side of road exposed and beneath the inner valley. Their Rio strongly developed petrocalcic soil of the Grande fault was projected beneath Sunport surface, which exhibits Stage III+ downtown Albuquerque, New Mexico, and carbonate morphology. This soil is overlain extended north to Bernalillo, New Mexico. by eolian sand that contains weakly Russell and Snelson (1994) proposed this developed buried soils (Fig. 1-9). 0.3

1-10 NMBMMR OFR 454C

Figure 1-8. Stratigraphic fence of Cenozoic deposits in the Calabacillas and northern Belen sub-basins. Data from oil test wells (Lozinsky, 1988, 1994; Connell et al., 1999; Tedford and Barghoorn, 1999; Maldonado et al., 1999; Black and Hiss, 1974). From Connell, Koning, and Derrick (2001).

8.5 Descend into unnamed northern tributary valley to Hell Canyon Wash. Prominent bench ahead just west of the front of the Manzanita Mountains is the northern Hubbell bench, which exposes Permo- Triassic rocks and thin well cemented conglomerate and sandstone of older Santa Fe Group deposits. 0.4 8.9 Tributary valley of Hell Canyon Wash. 0.3 9.2 On east-facing scarp of down-to-the-east McCormick Ranch fault. 0.3 9.5 Near western pinchout of piedmont deposits, which overlie ancestral Rio Grande deposits Figure 1-9. Photograph of petrocalcic soil of the here. Note that gravel is typically Sunport surface, exhibiting Stage III+ pedogenic subrounded to angular and composed of carbonate morphology overlain by fine- to medium- limestone, quartzite, schist, and granite. 0.2 grained sand of eolian origin. The overlying eolian 9.7 Road is on terrace of Memorial Draw, a sand commonly forms an extensive cover over the tributary to Hell Canyon Wash. It is named carbonate of the Sunport surface. Scale is 1.5 m. for a small memorial erected by the parents of one of several Navy fliers killed in a 7.5 Cross west-facing scarp of fault cutting crash here in 1946. This terrace is buried by ancestral Rio Grande deposits that are Holocene alluvium upstream and was overlain by a thin veneer of eolian sand. 0.4 removed by erosion downstream. Higher 7.9 Cross west-facing scarp of fault cutting terraces are cut by strands of the Hubbell ancestral Rio Grande deposits. Descend Spring fault zone. 0.6 east-sloping footwall dip slope. 0.5 10.3 Cross gas pipeline. 0.7 8.4 Cross west-facing scarp of fault cutting 11.0 Cross cattle guard. Large cottonwood at ancestral Rio Grande deposits. 0.1 11:00 is Hubbell Spring, on the eastern strand of the Hubbell Spring fault zone. The

1-11 NMBMMR OFR 454C Hubbell Spring fault zone is subdivided into Triassic strata on the footwall of the eastern strand of three major strands (Maldonado et al., 1999; the Hubbell Spring fault zone does not support this Personius et al., 1999). The eastern strand interpretation. Also, the presence of dark-gray forms the embayed escarpment of the Paleocene mudstone in wells on the Isleta-Sandia Hubbell bench and juxtaposes reddish- National Labs boundary (Thomas et al., 1995) brown Permo-Triassic sandstone and indicate fine-grained, low energy deposition during mudstone against deposits of the Santa Fe early Cenozoic time. Another possible explanation is Group. The central and western strands of that the limestone was deposited by streams draining the Hubbell Spring fault zone commonly the western front of the Manzanita Mts. have prominent scarps and are Pennsylvanian limestone is well exposed along the geomorphically young and have rather eastern basin margin and is also exposed on the distinct linear traces. Note the large footwall of the eastern Hubbell Spring fault on the Cottonwood at 1:00, which is on the central lands of the Sandia National Laboratories and strand of Hubbell Spring fault zone and is Kirtland Air Force Base, which abuts the northern the location of Stop 2-2. 0.4 boundary of the Isleta Reservation. 11.4 Pass intersection with road to Hubbell Spring to left. 0.6 12.0 Pull off road. STOP 1-2. Hubbell Spring fault zone. Hubbell Spring 7.5’ quadrangle, GPS: NAD 83, UTM Zone 013 S, N: 3,865,030 m; E: 358,090 m. At this stop we examine some spring deposits on the footwall of the central strand of Hubbell Spring fault zone, tectonic controls on groundwater and sedimentation, and paleoseismicity of the Hubbell Spring fault zone. Wells on south side of road encounter water at about 6 m below land surface. A deeper groundwater monitoring well (28D), drilled about 25 m north of the road, exhibits decreasing water levels with depth, indicating that this is a groundwater recharge area associated with this fault (Fig. 1-10). The high level of groundwater is also indicated by the presence of the large Cottonwood on the hanging wall of this fault strand. There are two prominent springs associated with this strand of the Hubbell Spring fault zone. Hubbell Spring and Ojo de la Cabra (Goat Spring) are about 2.5 km north and south of this stop. Deposits encountered in well 28D indicate that fluvial deposits of the ancestral Rio Grande interfinger with limestone-bearing piedmont deposits derived from the front of the Manzanita Mountains. The presence of fluvial deposits of the ancestral Rio Grande is supported by observations of similar strata exposed in a trench on the footwall of the central Hubbell Spring fault zone to the north (Personius et al., 2000). This well bottomed in Figure 1-10. Stratigraphic column of monitoring well limestone that we interpret to represent conglomerate MW28D drillhole and stratigraphic interpretations. from the piedmont member of the Sierra Ladrones The black rectangles depict upper (S1) and lower Fm, rather than from the Madera Group, which (S2) screens, which have associated water levels of would be much lower in the stratigraphic section, and 9.5 m and 37.7 m bls, respectively. below Paleogene-Triassic red beds, which were not encountered in cuttings sampled from this well. If The presence of ancestral Rio Grande deposits this limestone interval is the Pennsylvanian Madera less than 2 km west of the Hubbell bench, which is limestone, it then requires that about 580 m of underlain Permo-Triassic red beds indicates that the Permo-Triassic rocks (estimated from eastern slope Rio Grande was at least 12 km east of its present of Sandia Mountains; Ferguson, 1996) be missing course. Geologic mapping of the region and from the drillhole section. This interpretation would stratigraphic studies within the two largest tributary suggest the presence of reverse faulting, probably of canyons to the Rio Grande, Hell Canyon Wash and Laramide age; however, the presence of Permo- Tijeras Arroyo, do not support the presence of a

1-12 NMBMMR OFR 454C buttress unconformity or paleobluff line between 27-34 ka, and 11-14 ka , respectively (Personius et early Pleistocene deposits of the ancestral Rio Grande al., 2000). Unit 5 is offset by the fault and unit 9 and eastern-margin piedmont deposits. Instead the buries the fault. Stratigraphic relationships of units 6- stratigraphic relationships in these arroyos suggests 8 relative to the fault are not apparent. The older an interfingering relationship between the axial- alluvial deposits were dated using Uranium-series fluvial and transverse piedmont system, as disequilibrium methods and yielded ages ranging recognized in elsewhere in Plio-Pleistocene basin-fill from 70-244 ka, with the best date of 92±7 ka systems, such as the Palomas Fm of southern New (Personius et al., 2000) for a trench containing the Mexico (Mack and Seager, 1990; Gile et al., 1981). Stage IV carbonate soil on the footwall. In contrast, the CS model implies the presence of a Interpretation of the fault-rupture history for this major stratal discontinuity along the eastern basin strand of the Hubbell Spring fault indicate three margin that would juxtapose early Pleistocene episodes of movement during late Pleistocene time deposits against older (Pliocene) strata. Intrabasinal (Fig. 1-13). The latest event is estimated to have normal faults could act as this unconformable occurred during latest Pleistocene time. boundary; however, the presence of ancestral Rio Slip-rate estimates for basin-margin faults that Grande deposits across traces of the central Hubbell cut across the seismogenic crust are on the order of Spring fault suggests that this fault strand does not 0.02-0.2 mm/yr (20-200 m/m.y.). Slip-rate estimates exert enough control over the eastern limit of the for intrabasinal faults in the Albuquerque area are on axial-fluvial system during late Pliocene(?) time. The the order of 0.004-0.05 mm/yr (4-50 m/m.y.) stratigraphic relationship in MW28D indicates (Personius, 1999). Estimated recurrence intervals for structural control on the stratigraphic position of basin-margin and intrabasinal faults are 10-50 ka and ancestral Rio Grande deposits, however, the relative 10-200 ka, respectively (Personius, 1999). Thus, lack of reworked extrabasinal detritus in the faulting of the 0.7-1.2 Ma Sunport surface would piedmont section suggests that faulting did not result in between 3-60 m of movement across produce a significant escarpment during Plio- intrabasinal faults. Pleistocene deposition. East and southeast of the water tank at Stop 1-2 One of the younger strands of the Hubbell Spring are low hills interpreted to be former spring mounds. fault zone was studied by Steve Personius of the U.S. At the surface of these mounds and in interbedded Geological Survey in the fall of 1997 (Personius et alluvial and eolian deposits are layers of fragmented al., 2000). A trench was excavated on the steepest, plates and nodules of micritic calcium-carbonate most youthful looking fault scarp near the northern sandstone. One such spring mound is exposed along end of this fault zone, about 2 km to the north of this the footwall of the Hubbell Spring fault on the north stop (Figs. 1-11 and 1-12). Seven stratigraphic units side of the road (Fig. 1-14). This exposure has a were described in the excavation. These deposits sharp base with underlying uncemented sand. Other consist of a lower light-gray fluvial deposit (unit 1) exposures of spring deposits have sharp bases and that is overlain by locally derived alluvial deposits large masses of oxidized and hydrated iron and (unit 2). These are overlain by a series of eolian and manganese stain deposits red, orange, yellow, and alluvial deposits (3-8). The lowest deposit was black. In reduced environments, reduced iron, and recognized as fluvial and correlated with the early stains sediments green, gray, and black. These Pleistocene Santa Fe Group (Personius et al., 2000), deposits commonly contain root molds or casts and however, provenance of this deposit was not represent precipitation in poorly drained sediment, indicated. These deposits contain rounded volcanic such as those along springs. These features differ and metaquartzite pebbles having a strong affinity to from more common pedogenic features that are ancestral Rio Grande deposits, which were also typical of the well-drained semi-arid soils. Features recognized on the footwall of this strand of the common in well-drained, semi-arid soils include Hubbell Spring fault at monitoring well MW28D. distinctive horizonization, and a gradual downward Soils described on alluvium on the far-field part of decrease in calcium-carbonate cement and soil the footwall block indicate the development of Stage structure. Exceptions to these morphologic IV pedogenic carbonate morphology (Personius et differences can occur across major textural al., 2000). The younger eolian sediments of units 4, boundaries. Also, spring and pedogenic carbonates 5, and 7 are composed of eolian sand and were dated may be reworked or superimposed along fault zones using thermoluminescence (TL) and infra-red or major escarpments, such as along the edges of the stimulated luminescence (IRSL) methods at 52-60 ka, Cañada Colorada surface to the east. (Fig. 1-15).

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Figure 1-11. Geologic map of trench site area, northern Hubbell Spring fault zone (Personius et al., 2000). The trench site is about 2 km north of stop 1-2.

Figure 1-12. Part of paleoseismic trench across central strand of the Hubbell Spring fault zone (Personius et al., 2000), illustrating displacements of units 1-4.

1-14 NMBMMR OFR 454C Continue driving east on SP-60. 1.0 13.0 Whaleback feature at 9:00 is deformed piedmont conglomerate and underlying Permian sandstone on footwall of eastern strand of the Hubbell Spring fault zone (Fig. 1-16). The northern Hubbell bench is deeply embayed by streams originating from the Manzanita Mountains. The escarpment formed by the central Hubbell Spring fault has been eroded to the east by as much as 640 m by Cañada Colorada, resulting in the development of a sinuosity value (Bull, 1984) of 3.7 (Karlstrom et al., 1997). 0.3 Figure 1-13. Time-displacement diagram for the Hubbell Spring fault zone (Personius, 1999). The two oldest dates are U-series ages on calcic soil rinds developed on alluvial gravels that predate the oldest event. The younger dates are based on thermoluminescence (TL) ages on sandy colluvial/eolian deposits that are interpreted to closely post-date surface-faulting events.

Figure 1-16. Photograph look north of trace of central strand of Hubbell Spring fault zone, marked by low hill in the middle ground. Sandia Mountains in distance.

13.3 Cross cattle guard. Road to southeast is SP- 603. Continue straight and ascend deposits of colluvium, alluvium, and spring deposits Figure 1-14. Photograph of spring deposits on along edge of northern Hubbell bench. 0.3 footwall of central strand of the Hubbell Spring fault 13.6 Contact between east-tilted Yeso Fm zone. Note sharp base and top of this <10-cm thick (Permian) overlain by 15-20 m of well- deposit of micritic calcium-carbonate cemented cemented, clast- and matrix-supported, sandstone. limestone-bearing conglomerate (Fig. 1-17). This conglomerate is well cemented by fine- grained sparry calcite. The gorge to the south is Hell Canyon Wash. Note older surfaces above piedmont-plain south of Hell Canyon. 0.3 13.9 Limestone cobbles and boulders next to road are completely covered with thick calcium- carbonate. Ascend onto the Cañada Colorada surface, a gently west-sloping constructional surface of probable Pliocene age formed on a wedge of well-cemented conglomerate and sandstone derived from Figure 1-15. Conceptual diagram of spring-deposit the front of the Manzanita Mountains. White formation and the spatial and hydrologic relationship pebble gravel on road to the east is to soil development in fault blocks with identical composed mostly of hard petrocalcic peds of alluvium on both sides. As calcium-carbonate the Cañada Colorada soil. Mouth of Hell saturated water drains from the uplifted block to the Canyon at 12:00. Mouth of Cañada downthrown block, calcium-carbonate is precipitated Colorada at 10:00. Note that the banded in a narrow wedge (Love and Whitworth, 2001). rocks (limestone of the Pennsylvanian Hachures indicate soils. Madera Group), which form the topographic divide of the Manzanita Mountains, are dropped down-to-the-west by a series of 1-15 NMBMMR OFR 454C faults at 10:00. Buildings to the north are (northern Albuquerque and Belen basins) in research facilities of Sandia National a scissors fault manner. Geologic mapping Laboratories. The northern Manzanita and aeromagnetic studies (Maldonado et al., Mountains are deeply embayed and have a 1999; Grauch, 2001) indicate that the Tijeras range front sinuosity of about 6. The shiny fault zone appears to merge into, and metallic structures on the lone hill, just west probably connects with or is cut by, faults of of the mountain front, are the Starfire the Hubbell Spring fault zone, instead of Optical Observatory, built as part of the continuing across the basin as a discrete, Strategic Defense Initiative of the 1980s. sub-basin bounding structure as suggested This structure sits on an inselberg of by Russell and Snelson (1994). The east- Proterozoic schist on the footwall of the tilted dip-slope of the Sandia Mountains are “range-bounding” Coyote fault. The range is clearly visible to the north. 0.5 deeply embayed and the Coyote fault only 14.4 Note lower, inset surfaces associated with marks the range-front at the toes of major Cañada Colorada to the north. 0.6 spur ridges. This degree of embayment 15.0 Gate to north pasture. Junipers are present at suggests that the Manzanita Mountains are this elevation (~5680 ft). 0.6 tectonically inactive. Scattered inliers of 15.6 Turn right (south) onto two-track road Pennsylvanian limestone are locally exposed towards windmill at 11:00. 0.4 on the piedmont-slope between the Coyote 16.0 Bottom of Memorial Draw. 0.2 and Tijeras fault zones. 16.2 STOP 1-3. Northern Hubbell bench. Park near windmill. Mount Washington 7.5’ quadrangle, GPS: NAD 83, UTM Zone 013 S, N: 3,862,250 m; E: 363,665 m. At this stop, we compare the deep dissection of the northern Hubbell bench and the broad, feature- poor landscape of the Llano de Manzano. Piedmont deposits of the eastern margin are locally derived and form typical proximal, medial, and distal facies. They commonly consist of subangular limestone, metamorphic, sandstone, and granitic pebbles and cobbles; boulders are common near the mountain front. Eolian sand sheets are common on medial and distal portions of the piedmont. The eastern margin of the basin can be divided into three geomorphic Figure 1-17. Photograph of well cemented, clast- domains: 1) incised axial and tributary river valley; supported, locally derived piedmont deposits exposed 2) weakly dissected piedmont; 3) deeply dissected on the northern Hubbell bench. Gravel is mostly piedmont (Fig. 1-18 and 1-19). rounded limestone and reddish-brown sandstone with The front of the Manzanita Mts is deeply minor granitic and metamorphic clasts. embayed and contains exposed or shallowly buried Pennsylvanian-Triassic rocks on the hanging wall of The Tijeras fault is a northeast-trending the range-bounding fault. Pleistocene-age fault scarps fault that has a long and complicated history are recognized on the intrabasinal Hubbell Spring of recurrent movement ranging from fault zone. In contrast, the front of the northern Quaternary to Proterozoic in age (Connolly Manzano Mts is rather linear and contains et al., 1982; Kelson et al., 1999; Abbott et Pleistocene fault scarps near the mountain front. al., 1995). The southwest projection of this South of the northern Hubbell bench, a well drilled feature into the Albuquerque Basin nearly about 3.7 km west of the mountain front on the coincides with the zone of Plio-Pleistocene Bosque Peak quadrangle (Bonita Land and Livestock basalt fields on the Llano de Albuquerque well, Karlstrom et al., 1999) encountered deposits of and generally corresponds to a shift in the Santa Fe Group to at least 186 m bls. Cuttings regional patterns of stratal tilt. These from this well indicated conglomeratic deposits features were used as evidence to suggest extend to about 64 m and overlie muddy sandstone to that the Tijeras fault zone continued across the bottom of the hole. the Albuquerque Basin as an The broad west-sloping piedmont is the Cañada accommodation zone (Russell and Snelson, Colorada surface, which is preserved on the footwall 1994). The Tijeras accommodation zone was of the eastern Hubbell Spring fault zone. This surface considered to represent a zone of weakness lies within the deeply dissected piedmont domain. I that resulted in accommodating stratal tilts contrast the Llano de Manzano is only slightly of the Calabacillas and Belen sub-basins dissected and rift-border drainages deposit sediment

1-16 NMBMMR OFR 454C onto the abandoned piedmont slope and basin-plain soils that could be used to discriminate the boundary of this geomorphic surface complex (Fig. 1-19). A between basin-fill and younger deposition; however, Pliocene age for the Cañada Colorada surface is exposures are not sufficient to do this on a regional suggested by geomorphic criterion: it lies about 52 m basis. Also the selection of stratigraphically lower above the plain of the Llano de Manzano, is deeply soils to define the end of Santa Fe Group deposition embayed, having a range-front sinuosity value of 3.7, posses considerable problems in correlation across and contains a 2 m thick petrocalcic soil that has the basin. Much of the deposition on this broad basin- affinities to Stage V carbonate morphologic plain/piedmont-slope occurred after development of development. Soils in a pit (MW10S) about 30 m the Rio Grande Valley. Late Pleistocene and north of the windmill are more than 2.2 m in Holocene deposits can be differentiated on the Llano thickness and contain Stage III+ to V(?) pedogenic de Manzano by the relatively weak soil development carbonate morphology (Fig. 1-20). Another trench and incision into older deposits that have more excavated about 2.7 km to the east (MW15) exhibits strongly developed soils. a similar soil that is over 2.1 m thick. Intrabasinal faulting also creates local conditions Driller’s notes from the nearby windmill (RWP- where suites of inset terrace deposits on the footwall 27, range water project) indicate the presence of become part of a soil-bounded aggradational about 20 m of conglomerate over reddish-brown succession on the hanging wall. From a practical shale to 91 m below land surface. The upper 20 m is standpoint, inclusion of deposits with the correlative to the older, well cemented piedmont stratigraphically highest, moderately developed soils conglomerate and sandstone of the Santa Fe Group is easier to differentiate and is less ambiguous that that forms a thin cap on the northern Hubbell bench. interpreting lower, poorly dated, soil-bounded These deposits are well cemented and are Pliocene, unconformities in the section. and perhaps Miocene in age. The age of this deposit Following a number of models of rift- is not well constrained but is older than the early sedimentation (see among others, Gawthorpe and Pleistocene deposits on the hanging walls of the Leeder, 2000; Mack and Seager, 1990; Leeder and central and eastern Hubbell Spring fault zone. Jackson, 1993; Leeder and Gawthorpe, 1987; Blair Longitudinal profiles of paleo-stream positions and Bilodeau, 1988; Dart et al., 1995), we propose on the Cañada Colorada surface tend to diverge that deposition along the eastern margin of the basin towards the basin. This basinward divergence results is strongly controlled by the activity of basin-margin in the development of flights of inset deposits and and intrabasinal faults. The activity of these faults suggests that streams are progressively entrenching strongly influences the location of the axial-river into the northern Hubbell bench, presumably in (ancestral Rio Grande) and interfingering piedmont response to base-level adjustments imposed by deposits derived from the Manzanita and Manzano activity on the many downstream strands of the Mts. During basinward migration of the rift-border Hubbell Spring fault zone. structure, portions of the former piedmont-slope and In contrast, the Llano de Manzano is a low-relief basin-floor are uplifted. Younger deposits bypass this basin-floor and piedmont slope with little footwall block, which becomes a local stratigraphic constructional topography, except locally along top (Fig. 1-22). Smaller drainages that are not intrabasinal fault scarps. With the exception of integrated with the axial-river tend to have their base Tijeras, Hell Canyon, and Abo Arroyos, the largest level set by these abandoned surfaces. Intrabasinal drainages of the eastern margin, all other drainages of faulting also tends to create local fault wedges. Many the mountain front are not integrated with the Rio of these wedges can be observed near the Grande, but instead have their base level set by the constructional tops of the basin-fill succession; Llano de Manzano (Fig. 1-21). Thus, deposits of however, these wedges can also be recognized in the these smaller, non-integrated drainages are nearly late Miocene (see map of Connell, 1998). indistinguishable from the underlying strata. The upper part of the basin-fill succession does contain Retrace route back to SP-60. 0.6

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Figure 1-18. Shaded-relief map illustrating variations in mountain-front morphology and piedmont dissection where streams that are not integrated with the Rio Grande and its entrenched tributaries deposit sediment across the low- relief slope of the Llano de Manzano.

Figure 1-19. View of Llano de Manzano south of northern Hubbell bench, illustrating deposition of range-front alluvial fans that prograded over the low-relief, feature-challenged slope of the Llano de Manzano.

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over probably Pennsylvanian or Permian rocks. Other monitoring wells drilled on the northern Hubbell bench indicate the presence of about 25-42 m of limestone- bearing gravel correlated to the piedmont deposits of the Santa Fe Group. These conglomerates overlie dark red shale and sandstone of the Permo-Triassic succession. Soil pit (MW8S) just south of road indicates that this deposit contains a soil with Stage III pedogenic carbonate morphology (Fig. 1- 23). 0.1 19.3 Descend riser to Holocene valley of Hells Canyon Wash. Guadalupe Peak at 12:00 with Pennsylvanian limestone nonconformably overlying Ojito granite (Karlstrom et al., 2000). 0.1 19.4 Crossing modern channel of Hell Canyon Wash. A low (<2 m high) terrace contains charcoal that was dated at 1220±60 yr BP (Beta 106204; dendrochronologically calibrated to 675-975 yr AD, ±2σ). 0.1 19.5 Note toes of mountain-front fans to your left. Canon de los Seis to southeast. Topography is slightly undulatory and buried soils are common. Exposures of gas line to south indicate an extensive, but Figure 1-20. Top: Log of soil pit in Cañada Colorado locally discontinuous cover of grus- surface. Ticks indicate pedogenic carbonate dominated sand with Stage I and II morphology of each horizon (e.g., single tick= Stage pedogenic carbonate development, overlying I, double tick=Stage II, triple tick=Stage III). Bottom: moderately developed calcic soil with Stage Photograph of extremely hard carbonate peds from II to III carbonate morphology. 1.1 MW-10S soil pit. Po and P1 denote older and 20.6 Note large cobbles and boulders in deposits. younger soils, respectively. 0.2 20.8 Descend riser onto terrace of Canon de los 16.8 Turn right onto SP-60. 1.6 Seis. 0.2 18.4 To your left is a clear view of down-to-the- 21.0 Arroyo exposures of late Quaternary cut and west normal faulting within the Manzanita fill terrace sequences. Windmill (RWP-10) Mountains drops the banded limestone of to left. 0.1 the Madera Group towards the mountain 21.1 Bear right and head south along fence. 0.6 front. 0.2 21.7 Turn right onto SP-59. 0.2 18.6 Turn right (south) onto SP-604. 0.3 21.9 Cross gas pipeline. 0.2 18.9 Descend Cañada Colorada surface into Hell 22.1 Descend low riser into younger grus- Canyon valley. Note buildings and dominated alluvium of Cañon de los Seis. abandoned mine workings to left on face of 1.8 Manzanita Mountains. 0.1 23.9 Limestone boulders along edge of Sanchez 19.0 Descend riser onto middle Pleistocene Canyon, a tributary to Hell Canyon. Suite of terrace of Hell Canyon. 0.2 inset terrace deposits of Hell Canyon to 19.2 The short red pipe about 20 m east of road is north. 0.9 the upper East Side Monitoring Well. This well encountered about 21 m of limestone- bearing conglomerate that overlies over 75 m of red clay and sand with limestone layers near the bottom of the hole (at 88 m bls). Groundwater is at about 34 m bls. About 2.9 km to the northeast, just west of the mountain front, a driller’s log of a windmill (RWP29) indicates about 21-32 m of gravel

1-19 NMBMMR OFR 454C

Figure 1-21. Longitudinal profiles of major tributary drainages to the Rio Grande. Top: Tijeras Arroyo, which enters the basin at the junction of the Manzanita and Sandia Mountains. Subsurface work (Hawley and Hasse, 1992; Hawley et al., 1995; Hawley, 1996; Connell et al., 1998) indicate the presence of a number of intrabasinal faults west of the range-bounding Sandia fault. These faults, however, do not significantly influence development of piedmont-slope surfaces. Bottom: Longitudinal profile of Hell Canyon Wash. Intrabasinal faulting by the Hubbell Spring fault zone significantly influences late-stage sedimentation of the Santa Fe Group and the development of piedmont surfaces. Uplift of footwall blocks resulted in the preservation of flights of piedmont and valley-fill units that become nearly indistinguishable from the aggradational succession on the hanging wall.

24.8 Cut in low, middle Pleistocene terrace soil with Stage III carbonate morphology across tributary to north contains a stack of and clay-rich Bt horizons. Younger grus- calcic soils (MW1S), illustrating a dominated sands overlie this soil. 0.2 succession of soils containing I+ (25 cm 25.0 Cross cattle guard. 0.2 thick), and III+ (90-125 cm thick) pedogenic 25.2 Cross over interfluve between Ojo de la carbonate morphology. A gas line excavated Cabra and Hell Canyon drainages. 0.5 across the piedmont exposed much of the 25.7 Turn to right and stay on SP-59. Descend piedmont-slope south of Hell Canyon Wash. onto terrace tread. 0.5 This trench contained a strongly developed

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Figure 1-22. Conceptual block diagram, illustrating regional patterns of Santa Fe Group sedimentation (inspired after Gawthorpe and Leeder, 2000). Deposition along the footwall of the basin (transverse and axial systems tracts, TST and OST, respectively) are influenced by the location and activity of intrabasinal normal faults. In particular, basinward migration of the eastern rift-border structure results in the preservation of a number of geomorphic surfaces on the footwalls of intrabasinal faults. Depending on the size and lithology of the footwall drainages, piedmont deposition may be integrated with the axial river (AST) or will grade to local base levels along the eastern margin. Stratigraphic (or syntectonic) wedges are locally preserved along exposed fault scarps (co).

on the footwall of the Manzano Mountains are not integrated with Hell Canyon Wash or the Rio Grande. These drainages terminate on abandoned, early Pleistocene basin-plain and piedmont-slope surfaces, which constitute base level control for such streams. At this stop four terrace levels are visible above the modern channel. The lowest terrace is 2.5-3 m above the modern channel and functioned as the floodplain/valley floor during the 20th Century and probably consists of Holocene fill. The second level is discontinuous and is ~6 m above the modern channel. This small local terrace deposit is cut into an adjacent 9-m high terrace level and could represent Figure 1-23. Log of soil pit on inset middle(?) local (autocyclic?) variations in arroyo cutting and Pleistocene terrace deposit of Hell Canyon Wash. filling, rather than being related to tectonically or Ticks indicate pedogenic carbonate morphology of climatically driven changes in the landscape. each horizon (e.g., single tick= Stage I, double However, other 6-m high terraces are present tick=Stage II, triple tick=Stage III). downstream. An extensive terrace is 9 m above the modern channel here. This terrace deposit is not 26.2 Descend riser. Junipers on lower tread preserved down stream. The next highest terrace is surfaces. STOP 1-4. Inset terrace deposits 10-11 m above the modern channel. This unit of Hell Canyon Wash. Hubbell Spring 7.5’ becomes a broad, extensive terrace deposit quadrangle, GPS: NAD 83, UTM Zone 013 downstream and is preserved on both sides of Hell S, N: 3,861,415 m; E: 362,310 m. Canyon Wash. The highest terrace is 12-13 m above This stop is an overview of the suite of inset the modern channel and locally forms a broad terrace deposits associated with Hell Canyon Wash. rounded drainage-divide that SP-59 follows. To the Upstream and to the east, Hell Canyon Wash is a west is an older surface that is 27 m above the rather broad valley. West of here is the canyon of modern channel. The problem with correlating Hell Canyon Wash, which entrenched into the upper terraces in this geomorphic setting is that they Santa Fe Group basin fill during early(?) or middle become discontinuous downstream and are buried by Pleistocene time. To the south, drainages developed 1-21 NMBMMR OFR 454C eolian and alluvial sediments upstream. Their age, 30.7 STOP 1-5. Hell Canyon Wash. Hubbell climate and tectonic significance remain elusive. Spring 7.5’ quadrangle, GPS: NAD 83, Turn around and head back to MM 25.7. 0.2 UTM Zone 013 S, N: 3,862,700 m; E: 26.4 Turn right (west) onto Hell Canyon Road 355,420 m. (SP-625), heading west on interfluve of Ojo A stratigraphic section measured along the de la Cabra (Goat Spring) drainage. 0.5 southern margin of the arroyo is on the footwall of an 26.9 Cross cattle guard. 0.6 intrabasinal fault. The lower part of this section 27.5 Descend into Ojo de la Cabra drainage. 0.1 contains deposits of the ancestral Rio Grande that 27.6 Road crosses terrace remnant, which merges contain locally abundant pumice pebbles. A pumice into the valley floor upstream and is buried was dated using the 40Ar/39Ar method at 1.71 Ma. by piedmont alluvium farther east. 0.1 Geochemistry of this dated pebble indicates that it is 27.7 Road parallels Holocene terrace to south that chemically similar to the Bandelier Tuff (N. Dunbar, contains charcoal and snails. 0.2 2001, personal commun.). However, its age is 27.9 Notice the presence of phreatophytes (e.g., slightly older than the lower Bandelier and may be reeds and rushes) as you pass the spring of related to the pre-caldera San Diego Canyon Ojo de la Cabra (Goat Spring). Note the ignimbrite. About half-way up the slope is a cross- abundance of Mesquite and Creosote down bedded pumice-bearing pebble conglomerate that is stream. We are near the northern limit of well cemented with sparry calcite and forms elongate Creosote, which defines the northern limit of concretions (Fig. 1-24). The orientations of such Chihuahuan Desert vegetation. 0.2 elongate concretions are bi-directional indicators of 28.1 Confluence between Ojo de la Cabra paleo-groundwater flow (Mozley and Davis, 1996). drainage with Hell Canyon Wash. Two Assuming that paleo-groundwater flow directions discontinuous levels of terraces are present roughly mimic the present southward course of the here. Piedmont deposits consist of sandstone Rio Grande, the orientations of these elongate with interbedded clast-supported concretions are south-southeast. Paleocurrent conglomerate composed mostly of limestone orientations determined from cross bedding are with subordinate metamorphic and minor south-southwest, but similar to the paleo- reddish-brown sandstone cobbles and groundwater flow indicators. A succession of fine- to boulders. 0.4 medium-grained sand with scattered concretionary 28.5 Note terrace deposits midway up margins of sandstone and rhizoconcretionary intervals is Hell Canyon Wash. 0.5 typically present between the underlying fluvial and 29.0 Buried paleocanyon on north side of overlying piedmont deposits. Cementation of the drainage contains about 10-15 m of bouldery underlying fluvial succession is also common near piedmont sediments. 0.2 the boundary (laterally or vertically) with eastern- 29.2 Arroyo terrace deposit to north is inset margin piedmont deposits. Fluvial and eolian- against upper Santa Fe Group. 0.1 dominated deposits interfinger with, and are overlain 29.3 Hell Canyon Wash broadens, presumably by, locally derived piedmont deposits of the Manzano because of the presence of weakly cemented Mts. fluvial deposits of the ancestral Rio Grande The top of the section contains a strongly below just level of valley floor. Drainages developed soil with Stage IV pedogenic carbonate developed in ancestral Rio Grande deposits morphology and a strongly developed stone commonly form broad tributary valleys, pavement. This surface is a remnant of the footwall whereas, tributary drainages incised into the of a strand of the Hubbell Spring fault zone. Later better cemented piedmont deposits piedmont deposits bypassed this remnant to the north commonly contain narrower and steeper- and south of Hell Canyon. Deposits of these later walled valleys. 0.4 piedmont systems are only slightly offset by this fault 29.7 Paleo-canyon backfill (s) exposed on north strand, but are displaced more by other strands to the rim of Hell Canyon Wash. Historic gravel west. The tops of limestone pebbles on this bars on valley floor may have been constructional surface are commonly flattened, deposited during flood in the 1920s(?). probably by the dissolution of carbonate. The There are anecdotal accounts of a flood in undersides of these clasts are quite deeply pitted and Hell Canyon that reached the Rio Grande in have a pendant morphology caused by the dissolution the 1920s, however, the extent of this flood of calcite. Later re-precipitation of white micritic has not been independently verified. 0.6 carbonate indicates deposition after an earlier stage of 30.3 To your right at valley floor level are well dissolution. These cements are quite different than cemented, gently east-tilted exposures of the sparry, phreatic calcite exposed below in the early Pleistocene pumice-bearing ancestral fluvial deposits of the ancestral Rio Grande (Fig. 1- Rio Grande deposits. 0.1 25 and 1-26). 30.4 Cross cattle guard. 0.3

1-22 NMBMMR OFR 454C

Figure 1-25. Photograph looking to the east at well cemented extrabasinal, cross bedded sandstone and rounded conglomerate of the ancestral Rio Grande deposits of the Sierra Ladrones Fm. The banded appearance is the result of southerly oriented sandstone concretions indicating a southerly direction of paleo-groundwater flow. Scale is 1.5 m high.

Thus, this westward progradation of the Rio Grande would result in the development of an unconformity of increasing temporal magnitude to the west (see Fig. 1-6). The nature of this contact will be explored on Day 2. This westward progradation of the ancestral Rio Grande and piedmont deposits is recognized throughout much of the basin (see Connell et al., 1995; Cather et al., 2000; Smith et al., 2001 for examples) and may be responsible for the present position of the Rio Grande Valley, prior to 0.7-1.2 Ma entrenchment. This relationship may also explain why deposits of the ancestral Rio Grande in the Albuquerque area are rather sparse west of the Rio Grande Valley. Geologic studies of the Isleta Reservation do not support the presence of an eastern buttress Figure 1-24. Stratigraphic section of Hell Canyon unconformity between early Pleistocene fluvial Central Section measured along southern margin of deposits of the ancestral Rio Grande and older basin Hell Canyon. This marks the approximate eastern fill. Figure 1-28 is a conceptual model showing limit of exposure of pumice-bearing fluvial deposits interpreted differences in bounding unconformities of the ancestral Rio Grande, which become buried to and stratal geometries one might expect between the east. Hachures denote soils. Roman numerals aggrading basin fill and incised river valley indicate pedogenic carbonate morphologic stage. deposition. Continue driving west on SP-625. 0.5 Comparisons of surface and available subsurface 31.2 Ancestral Rio Grande deposits low in stratigraphic data indicate the development of a canyon walls, east of a strand of the Hubbell westard-prograding wedge of ancestral Rio Grande Spring fault zone. These deposits commonly and eastern-margin piedmont deposits (Fig. 1-27). form “flat irons” (Gerson, 1982) that are This westward progradation of the ancestral Rio separated from the modern valley border Grande would result in onlap onto deposits of the slopes. These are probably the result of Arroyo Ojito Fm (the western oblique fluvial differential permeability and runoff contrasts system). The top of the Arroyo Ojito Fm is defined between the more permeable ancestral Rio by the Llano de Albuquerque surface, which is late Grande deposits and the less permeable Pliocene in age (see discussions in Day 2 road log). piedmont alluvium. North side of Hell Canyon Wash widens. Badlands contain interfingering distal piedmont and ancestral Rio Grande deposits. 0.1

1-23 NMBMMR OFR 454C 31.3 Pass connecting road to SP-624. Bear left. 34.5 Cross trace of Palace-Pipeline fault zone, 0.2 which displaces the Llano de Manzano by 31.5 Road to right across dam leads to exposures about 18 m on south side of Hell Canyon of interfingering transition between Wash. Terrace to your left (south) piedmont and fluvial deposits. 0.2 terminates near trace of fault. This terrace is 31.7 Valley broadens and interfingering piedmont probably middle to late Pleistocene in age. It deposits become thinner. 0.4 is not clear whether the fault displaces this 32.1 High terrace deposits across valley to your terrace to the extent that it is buried below right. Piedmont deposits above are generally the valley to the west. Rather, this terrace is less than 2 m thick and cap both edges of probably too thick to be offset that much. Hell Canyon Wash. 0.4 Capture of new tributaries west of the 32.5 Low terrace deposit from Memorial Draw, Palace-Pipeline fault and erosion of the to north, which follows the McCormick valley margins may provide a better Ranch fault. 0.5 explanation for the lack of terraces to the 33.0 Cross road from northeast. Large boulders west. 0.7 of upper Bandelier Tuff found to south (Fig 35.2 Cross cattle guard. Exposures at 9:00 and 1-29). Note terrace, about 7 m above road, 2:00 contain an ash preliminarily dated at along south side of Hell Canyon Wash. 0.3 1.55 Ma and correlated to the Cerro Toledo 33.3 Terrace deposit continues on south side of Rhyolite. Earlier attempts to date this fine- Hell Canyon but become more dissected to grained ash yielded a range in ages from the west. 1.2 1.05-1.6 Ma. 0.6

Figure 1-27. Stratigraphic fence across a portion of the Isleta Reservation and Los Lunas volcano, illustrating stratigraphic relationships among upper Santa Fe Group deposits. Horizontal distances are not to scale. See Plate II for approximate locations of stratigraphic sections. The Zia fault section (ZS) is about 45 km north of CdRPS-1 and contains the ~3.3 Ma Nomlaki Tuff (Connell et al., 1999). Hachures denote soils. Roman numerals indicate pedogenic carbonate morphologic stage.

1-24 NMBMMR OFR 454C contain pumice-bearing ancestral Rio Grande deposits. 0.7 36.8 White bed at 3:00 is ash dated at 1.55 Ma and correlated to Cerro Toledo Rhyolite. This ash is about 10 m below the Sunport surface. (Fig. 1-30). 0.8 37.6 Bluffs to east expose fine-grained light- brown sand overlain by gray deposits of the ancestral Rio Grande. This contact descends to the south and is buried at the mouth of Hell Canyon Wash. 0.8 38.4 Cross cattle guard and turn right onto state highway NM-47. Merge into left lane. 0.4 Figure 1-26. Photograph of constructional surface at 38.8 Turn left onto state highway NM-147 top of stratigraphic section, illustrating a deeply towards Isleta Pueblo. Bluff to north is low pitted limestone pebble covered with micritic terrace. 0.2 carbonate. The interlocking flat pebbles form a 39.0 Cross Rio Grande. The concrete structure moderately to well developed desert pavement. that spans the river is the Isleta Diversion Limestone pebble tops are commonly flattened and Dam of the Middle Rio Grande Conservancy subparallel to the ground surface. District, which diverts water from the Rio Grande to a number of acequias (ditches) for 35.8 Turn right (north) towards cattle guard at irrigation agriculture between of Isleta and north end of Hell Canyon Wash. 0.2 San Acacia, New Mexico. Much of this 36.0 Cross cattle guard. 0.1 water is returned to the river via a series of 36.1 Begin pavement, turn north and drive on drains. 0.3 floodplain of Rio Grande. Bluffs to east

Figure 1-28. Schematic stratigraphic relationships comparing deposition on deeply dissected and weakly dissected piedmonts and the entrenched river valley. Units Qro and Qry denote younger and older inset fluvial deposits.

1-25 NMBMMR OFR 454C country. They returned in 1716, brining their Hopi relatives with them. The present Pueblo was built in 1709 by scattered Tigua families. Most of the Hopi later returned to Arizona, but have retained their ties with Isleta. Reservations of Acoma and Laguna migrated to Isleta in the early 1800s because of drought and religious differences at their home pueblos. Thus, Isleta has incorporated a variety of pueblo people (Taken from Connolly, Woodward, and Hawley, 1982, p. 29). 0.1 39.4 Bear right at cylindrical cement water tank Figure 1-29. Photograph of boulder of upper and continue west to plaza. 0.1 Bandelier Tuff within early Pleistocene sand and 39.5 Cross plaza and church at Isleta. 0.1 gravel of the ancestral Rio Grande deposits of the 39.6 Turn right (north) at intersection west of Sierra Ladrones Fm. This boulder is exposed in a plaza. 0.2 gully just south of Hell Canyon Wash. 39.8 Turn left onto state Highway NM-147. 0.7 40.5 Cross railroad tracks and immediately turn left onto NM-314. 0.3 40.8 Turn right onto Tribal Road TR-74. Drive slow and watch for speed bumps. 0.2 41.0 Turn left onto NM-45 at stop sign, then make a quick right onto NM-317 towards junction with I-25. 0.8 41.8 Ascend onto Los Duranes Fm, a late-middle Pleistocene fluvial deposit of the ancestral Rio Grande that is inset against Santa Fe Group basin fill. The top of this deposit was named the Segundo Alto surface by Lambert (1968). The age of the top is constrained by Figure 1-30. Photograph of white fluvially reworked the 98-110 ka Cat Hills flows, which ash of Cerro Toledo Rhyolite exposed along eastern overlies the Los Duranes Fm (Fig. 1-31). margin of Rio Grande Valley. This ash lies about 30 About 25 km to north in NW Albuquerque, m above the local base of early Pleistocene sand and tongues of the 156±20 ka (U/Th date from gravel of the ancestral Rio Grande deposits of the Peate et al., 1996) Albuquerque volcanoes Sierra Ladrones Fm. are interbedded near the top of the Los Duranes Fm. These constraints indicate that 39.3 Turn left to Isleta Pueblo (pop: 4409). The deposition of the Los Duranes Fm ceased Pueblo of Isleta (Spanish for island) was between 98-156 ka. A prominent tributary built on a slightly elevated fluvial-terrace terrace deposit in Socorro Canyon, about deposit of the Rio Grande. A basalt flow 105 km to the south near Socorro, New crops out on the northern side of the “island Mexico, has been dated using cosmogenic of Isleta.” The original pueblo was located 36Cl dating methods, indicates a cessation in on the site of the present pueblo when deposition at 122±18 ka (Ayarbe, 2000). Coronado visited the area in 1540.The Correlations to this better-dated deposit have Spanish established the Mission of San not been made, but suggest that the Antonio de Isleta by 1613. Plains-Indian development of the Segundo alto terrace raids caused the Pueblo Indians living east tread surface may be near this vintage. 0.3 of the Manzano Mountains to move to Isleta 42.1 Cross I-25 overpass. Continue west. 0.2 around 1675. The Isleta Pueblo did not 42.3 Cross cattle guard, heading west on Segundo actively participate in the Pueblo Revolt alto surface. Pavement ends. Black hill to against the Spanish in 1680 and became a right (north) is the 2.78 Ma Isleta volcano refuge for Spanish settlers. In spite of this (Maldonado et al., 1999). 0.2 Governor Otermin captured the pueblo in 42.5 Low eastern limit of younger flows of Cat 1681 and took 400 to 500 prisoners with him Hills volcanic field, which have been to El Paso where they settled at Ysleta del 40Ar/39Ar dated between 98-110 ka Sur. The remaining population abandoned (Maldonado et al., 1999). 0.8 the Pueblo of Isleta and fled to Hopi

1-26 NMBMMR OFR 454C carbonate morphology are present at this upper contact. A bed of pumice-bearing pebbly sand is exposed locally in upper part of the San Clemente graben succession (Fig. 1-33). This pebbly sand bed contains pumice that has been chemically correlated to the Bandelier Tuff and yields a 40Ar39Ar date of 1.2 Ma, indicating that it is correlated to the upper Bandelier Tuff. These deposits overlie a soil developed on deposits of the Arroyo Ojito Fm. This soil is interpreted to represent a buried correlative of the Llano de Albuquerque soil, which marks the local top of Arroyo Ojito Fm deposition. The presence of Bandelier Tuff suggests that these sandy deposits are Figure 1-31. View, looking west, of late Pleistocene part of the ancestral Rio Grande deposits of the Sierra basaltic flows of the Cat Hills volcanic field Ladrones Fm and represent the westernmost overlying the Segundo alto surface of the Los progradation and temporary spillover of the ancestral Duranes Fm. Rio Grande into the San Clemente graben during early Pleistocene time (Fig. 1-34). 43.3 Pass transfer station to your left. The Shell Isleta #2 well was drilled just west of Isleta Turn around and retrace route back to paved road volcano to the north. 0.7 west of I-25. End of day one road log. 8.0 44.0 Flows of the late Pleistocene Cat Hills volcanic field to the south. 1.3 45.3 Cross wash and turn left (southwest) on dirt road. 0.5 45.8 The prominent hill to south is the Pliocene and early Pleistocene Los Lunas volcano. Volcano intruded deposits of the Arroyo Ojito Fm and Sierra Ladrones Fm. 0.6 46.4 Pass through locked gate. 0.3 46.7 Drive on Cat Hills flow 1. 0.4 47.1 On Arroyo Ojito Fm. 0.2 47.3 Flow of unit 1 of the Cat Hills basalt field. 0.3 47.6 Exposures of the Arroyo Ojito Fm. 0.5 48.1 On flow 1 of Cat Hills field. Excellent view Figure 1-32. View to west of the 98-110 ka flow of of north side of Los Lunas volcano. 0.2 the Cat Hills volcanic field, which overlies a strongly 48.3 Descend into eroded units of sand and mud developed soil that exhibits Stage III pedogenic exposed in the San Clemente graben. 0.1 carbonate morphology. This soil is developed on 48.4 Cross drainage covered by eolian sandsheets sand and mud of the San Clemente graben, which and fine-grained mud and sand dominated overlies a soil developed on the Ceja Member of the deposits that fill the San Clemente graben. Arroyo Ojito Fm. 0.4 48.8 North-trending alignment of vents of the Cat Hills field to the west. 0.5 49.3 Pass under powerlines. 0.4 49.7 Bear right at corral and windmill. 0.4 50.1 Pass Cat Hills basalt flow overlying strongly developed soil on right. 0.1 50.2 STOP 1-6. San Clemente graben and Cat Hills volcanic field. Dalies 7.5’ quadrangle, GPS: NAD 83, UTM Zone 013 S, N: 3,856,670 m; E:332,080 m. Deposits within the San Clemente graben are mostly muddy sand and sand of eolian, fluvial, and colluvial origin. These deposits rest on a soil developed on the upper Arroyo Ojito fm (Ceja Mbr) and are overlain by flows of the Cat Hills field (Fig. 1-32). Strongly developed soil with stage III+

1-27 NMBMMR OFR 454C Figure 1-33. Stratigraphic column of San Clemente graben site, illustrating about 40 m of sand and mud overlying a soil developed on deposits assigned to the Ceja Member of the Arroyo Ojito Fm. About 18 m above the basal contact is a bed of sand containing pebbles of fluvially recycled upper Bandelier Tuff (verified by 40Ar/39Ar dating and geochemical correlation; W.C., McIntosh, and N. Dunbar, unpubl.). Hachured lines denote soils. Roman numerals indicate pedogenic carbonate morphologic stage.

Figure 1-34. Cross section across western edge of basin and Los Lunas volcano. Note that the Llano de Albuquerque is faulted down towards the east and is buried by sediments accumulated in the San Clemente graben, which contains beds of early Pleistocene ancestral Rio Grande deposits in it. The scarp along the eastern edge of Los Lunas volcano is either faulted or is an erosional escarpment formed during entrenchment and subsequent aggradation of the middle Pleistocene Los Duranes Fm. A notch along the eastern flank of Los Lunas volcano marks the edge of an upper flow. Units include the Arroyo Ojito Fm (To), alluvium in San Clemente graben (Qss), ancestral Rio Grande deposits of the Sierra Ladrones Fm (Qsa), alluvium of Los Lunas volcano (Qav), 1.26 Ma trachyandesite of Los Lunas volcano (Qv), older volcanic rocks of Los Lunas volcano (Tv), and inset fluvial deposits of the Los Padillas (Qrp) and Los Duranes (Qrd) fms. Hachured lines denote major geomorphic surfaces, such and the Llano de Albuquerque and Llano de Manzano (LdM). Fallout ash and fluvially recycled pumice of the 1.22 Ma Bandelier Tuff (UBT) is present in units Qss and Qav.

1-28 NMBGMR 454C TH FRIENDS OF THE PLEISTOCENE, ROCKY MOUNTAIN CELL, 45 FIELD CONFERENCE

PLIO-PLEISTOCENE STRATIGRAPHY AND GEOMORPHOLOGY OF THE CENTRAL PART OF THE ALBUQUERQUE BASIN

SECOND-DAY ROAD LOG, OCTOBER 13, 2001

Geology of Southern Albuquerque and Tijeras Arroyo

SEAN D. CONNELL New Mexico Bureau of Geology and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

DAVID W. LOVE New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

J. BRUCE J. HARRISON Dept. of Earth and Environmental Sciences, New Mexico Institute of Mining and Technology 801 Leroy Place, Socorro, NM 87801

The following trip examines the geomorphic and stratigraphic setting of the inset (post-Santa Fe Group) fluvial succession of the ancestral Rio Grande, the stratigraphic and geomorphic relationships between the Llano de Albuquerque and Sunport surfaces, and the lithologic makeup and size distribution of the gravel of the western- margin facies and axial Rio Grande facies. During the trip we will also discuss potential problems inherent with extending lithostratigraphic and allostratigraphic concepts through the basin-fill system. Field-trip stops illustrated on Plate I.

Mi Description floodplain of the Rio Grande (MW-1 Isleta 0.0 STOP 2-0. Begin trip at south side of store and MW-2 Isleta, Hawley, 1996, appendix at the Isleta Lakes Campground, Isleta 7.5’ A). These floodplain deposits do not exhibit quadrangle (1991), GPS: NAD 83, UTM soil development and have very little Zone 013 S, N: 3,867,855 m; E: 346,955 m. depositional relief and significant portions (Note that the UTM ticks on this quad are of the inner valley have historically been incorrect). This trip begins on the floodplain flooded (see Kelley, 1982) prior to the of the Rio Grande. The stratigraphy of this construction of Cochiti and Jemez dams uppermost Pleistocene and Holocene deposit upstream. Thus, the inner valley is has been recently studied in detail for a hydrologically connected to the modern Rio liquefaction susceptibility evaluation Grande, whereas the late Pleistocene (Kelson et al., this volume). Drive east and deposits of the Arenal Fm are well above leave Isleta Lakes Campground. The inner flood stage. The age of the Los Padillas Fm valley of the Rio Grande is a floodplain is poorly constrained, but was likely laid surface bordered by dissected bluffs that are down during latest Pleistocene time after the partially buried by coalescent valley border Rio Grande incised about 85 m into alluvial fan deposits (Fig. 2-1). This lowest ancestral Rio Grande deposits of the late and youngest cut-and-fill deposit of the Rio Pleistocene Arenal Fm (a.k.a. Primero Alto Grande Valley formed very late in the terrace surface of Lambert, 1968), which sequence of episodic incision and partial contains soils having Stage I and II+ aggradation after the Rio Grande began to pedogenic carbonate morphology (Connell incise into Plio-Pleistocene basin fill of the et al., 1998a; Machette, 1997). Inner valley upper Santa Fe Group between 1.2-0.7 Ma. aggradation is demonstrated by an archaic Deposits of the inner valley, informally site located 4 m below the valley floor in the referred to herein as the Los Padillas north valley of Albuquerque (Sargent, formation (Connell and Love, 2000, 2001), 1987). Tributary aggradation may have represent the latest aggradational phase of slowed by middle Holocene time as the axial Rio Grande. The inner valley is indicated by a 4550±160 yr BP (Beta underlain by about 22 m of sand, gravel, and 109129; dendrochronologically calibrated to minor silt-clay deposits that form the BC 3640-2895 yrs ±2σ) date on charcoal

2-1 NMBGMR 454C within 2 m of the top of a broad valley Drillhole data near Isleta Lakes and just border fan near the mouth of Tijeras Arroyo north of Black Mesa, a basalt-capped mesa (Connell et al., 1998a). The lack of strong bordering the western margin of the inner soils between the terrace deposits of the valley, just west of Isleta Lakes, indicates ancestral Rio Grande and piedmont and that much of the floodplain succession is valley border deposits suggests that mostly pebbly sand and sand. Drillhole data piedmont and valley border deposition kept in the inner valley suggests that much of the pace with the development of the floodplain. Los Padillas Fm rests upon Pliocene Upper Pleistocene and Holocene sediments of the Arroyo Ojito Fm, which alluvial deposits are aggraded alluvial were laid down by areally extensive rivers aprons and channels cut into, or burying, derived from the western margin of the older deposits bordering the valley. The basin. Clay beds, locally recognized within progradation of Holocene valley border the Los Padillas Fm near Rio Bravo alluvial deposits across the floodplain Boulevard (about 8 km to the north; Connell indicates that present discharge of the river et al., 1998a) are interpreted to represent along this reach is inadequate to transport vertical accretion facies that are probably accumulated sediment out of the valley. The related to cut-off meander loops of the presence of progressively inset fluvial Holocene Rio Grande (cf. Kelson et al., deposits of the ancestral Rio Grande along 1999). These clay beds strongly influence the valley margins indicates that episodes of the flow of groundwater and the transport of prolonged higher discharge were necessary groundwater contamination from the rather to flush sediment and erode the valley. Such heavily industrialized portions of the inner erosional episodes must have occurred prior valley. 0.3 to aggradation of fluvial terrace deposits, 0.3 Railroad Crossing. Ascend valley border perhaps during times of increased discharge, alluvium derived from recycled sand and such as during full glacial events. gravel of the upper Santa Fe Group. Valley Progradation of middle Holocene valley border alluvium is poorly consolidated, border alluvium across the modern Rio weakly to non-cemented, typically low Grande floodplain suggests that deposition density, and exhibit weak to no soil-profile of tributary and piedmont facies occurred development with disseminated calcium during drier (interglacial) conditions, carbonate or Stage I pedogenic carbonate possibly coupled with increased monsoonal morphology at depth. These deposits form a precipitation. Deposition of fluvial terraces series of coalescent fans along the margins in semi-arid regions has been interpreted to of the valley. These deposits are commonly occur during the transition from wetter to prone to collapse upon wetting and have drier climates (Schumm, 1965; Bull, 1991). resulted in damage to buildings and homes The stratigraphic relationships of the Los in the Albuquerque area. 0.2 Padillas Fm and tributary and valley border 0.5 Isleta Eagle Golf Course to south, a 27-hole alluvial deposits support this concept. course operated by the tribe and is part of Stratigraphic constraints on the deposition of their growing resort complex. 0.4 the Los Duranes Fm, a middle Pleistocene 0.9 Turn left (north) at stoplight onto highway deposit of the ancestral Rio Grande, indicate NM-47. 0.1 that much of the deposition of this 1.4 Cross under I-25 overpass, keep in left lane. widespread terrace deposit had finished 0.2 prior to interglacial period of marine oxygen 1.6 Turn left and head south on NM-47 (South isotope stage 5 (ca. 128 ka), although Broadway). 0.1 deposition may have continued into the early 1.7 Get into right lane. 0.1 part of the late Pleistocene. Studies of a 1.8 Turn right onto southbound I-25 entrance lacustrine and eolian succession in the ramp. 0.3 Estanica basin (Allen and Anderson, 2000) 2.1 Merge with I-25 south (headed west). 0.5 indicate a wetter climate in the region 2.6 East abutment of I-25 bridge over Rio existing between about 15-20 ka, which Grande. Rio Grande channel ahead. 0.4 might have driven incision of the inner 3.0 Milepost 214. West bridge abutment. 0.5 valley; however, age control is lacking at the 3.5 Cross over Isleta Blvd. 0.3 base of the Los Padillas Fm.

2-2 NMBGMR 454C

Figure 2-1. Schematic east-trending cross sections (VE=10) across Rio Grande Valley, illustrating inset relationships among middle and late Pleistocene fluvial deposits of the ancestral Rio Grande and upper Santa Fe Group constructional surfaces of the Llano de Albuquerque (LdA) and Sunport (SP). Profile north of I-40 illustrating burial of the Lomatas Negras Fm by the middle Pleistocene basalt of the Albuquerque volcanoes (a). Profile near Isleta Lakes (b). Profile at Isleta Pueblo (c). Approximate elevations of major constructional surfaces of the late Pliocene Llano de Albuquerque, and early Pleistocene Sunport surfaces are illustrated as are inset deposits of the middle Pleistocene Lomatas Negras Fm (containing the ~0.66 Ma Lava Creek B ash), the late-middle Pleistocene Los Duranes Fm (constrained by middle and late Pleistocene lava flows of the 156 ka Albuquerque volcanoes and 98-110 ka Cat Hills volcanic field; Peate et al., 1996; Maldonado et al., 1999), the late Pleistocene Arenal Fm, and the latest Pleistocene-Holocene inner valley deposits of the Los Padillas Fm. The stippled pattern indicates local deposition of valley border fans.

3.8 Entering Isleta Reservation. Overpass of 4.4 Cross bridge over Old Coors Road, which drain and location of Isleta-Black Mesa follows a former course of the Rio Grande piezometer, which encountered 22 m of cut through the lava flow of Black Mesa. sandy fluvial deposits underlying the Rio Roadcut to right shows the edge of the Grande floodplain (Los Padillas Fm). 2.68±0.04 Ma (40Ar/39Ar date, Maldonado et Deposits are associated with the last al., 1999) Black Mesa flow overlying cross- incision/aggradation episode of the Rio bedded pebbly sands of the Arroyo Ojito Fm Grande. Incision probably occurred during and base-surge deposits from Isleta volcano. latest-Pleistocene time, and entrenched 40 m The tholeiitic Black Mesa flow has no below the late Pleistocene Arenal Fm. 0.6 outcrop connection with, and is slightly younger than, Isleta volcano, which forms

2-3 NMBGMR 454C

the dark, rounded hill ahead and to the right 7.1 Leave I-25 at exit 209 overpass to Isleta of the highway. A buried vent for the Black Pueblo. 0.1 Mesa flow is suspected in the floodplain 7.2 Turn left at NM-317 and head east towards area to left (Kelley and Kudo, 1978). 0.3 Isleta Pueblo. 0.7 4.7 Base-surge deposits of tuff cone associated 7.9 Descend riser of Segundo Alto surface and with emplacement of Isleta volcano in middle Pleistocene Los Duranes Fm. A soil outcrops on both sides of route. 0.5 described by S. Connell and D. Love, nearby 5.2 Change in primary dip direction of base- indicates that the Segundo Alto surface surge deposits at crest of tuff ring on right. exhibits Stage II carbonate morphology. 0.2 Overlying alkali-olivine basalt flows fill tuff 8.1 Water tanks to left. 0.2 ring and extend southeast beyond Isleta 8.3 Turn left at stop sign onto Old Coors Rd volcano. 40Ar/39Ar dates indicate that oldest (NM-45). 0.2 flow is 2.75±0.03 Ma and the second is 8.5 Low rounded quartzite-bearing gravel of an 2.78±0.06 Ma (Maldonado et al., 1999). ancestral Rio Grande terrace deposit inset Basaltic cinders correlated to the Isleta against red cinders of Isleta volcano (2.72- volcano flows are recognized in the Arroyo 2.79 Ma; Maldonado et al., 1999). 0.3 Ojito Fm exposed along the eastern margin 8.8 Low inset terrace deposit of the ancestral of the Rio Grande valley. These cinder- Rio Grande north of red cinder bluff. 0.1 bearing deposits are about 70 m (estimated) 8.9 Exposed south end of lava flow beneath stratigraphically below exposures of lower terrace gravel. 0.4 Pleistocene, Lower-Bandelier-Tuff bearing 9.3 Descend onto floodplain of the Rio Grande. sand and gravel of the ancestral Rio Grande Basalt flow and underlying base-surge facies of the Sierra Ladrones Fm. This deposits to west. These are part of the tuff stratigraphic relationship indicates that ring of Isleta volcano. The 2.68 Ma deposition of the Arroyo Ojito Fm continued (Maldonado et al., 1999) Black Mesa flow is after 2.72-2.78 Ma, thereby constraining the straight ahead and overlies deposits of the age of the mesa capping Llano de Arroyo Ojito Fm. 1.4 Albuquerque to between 2.7 to 1.6 Ma. 11.0 Cross under I-25 overpass and through water Based on local stratigraphy on both sides of gap cut by the Rio Grande. 0.5 the present valley, it is likely that the Llano 11.5 Leave Isleta Reservation. 0.6 de Albuquerque was abandoned as an active 12.1 Pass intersection with Malpais Rd. Travel fluvial fan prior to deposition of Lower along western margin of inner valley Bandelier ash and pumice gravel at ca. 1.6 floodplain. The low slopes to the west (left) Ma. Locally, the cinders of Isleta Volcano are the toes of coalescent valley border on the east side of the valley have alluvial fans. 1.4 experienced over 100 m of uplift with 13.5 Pass intersection with Powers Way (west). consequent erosion of the overlying units 1.2 before final deposition by the Rio Grande to 14.7 Turn left (west) onto Pajarito Rd. Ascend form the Sunport Surface. Because early valley border alluvium. The skyline mesa to Pleistocene terraces of the Rio Grande pass the west is the Llano de Albuquerque, the west of Isleta volcano at high levels, the interfluve between the Rio Puerco and Rio volcanic edifice probably was exhumed Grande drainages. Within next 0.5 miles, during middle and late Pleistocene time note the thin, discontinuously exposed white (Love et al., 2001). 0.1 band at top of Llano de Albuquerque (Cejita 5.3 Entering cut exposing basalt flow of Isleta Blanca of Lambert, 1968; Kelley, 1977). It volcano over base-surge unit (Fig. 2-2). is a strongly developed petrocalcic soil of Shell Isleta #2 well is about 1 mi. to the the Llano de Albuquerque surface. Note low west, where it reached a depth of 6482 m east-descending spur ridges, which are inset and ended in Eocene rocks. Lozinsky (1994) fluvial deposits of the ancestral Rio Grande. reports that the Santa Fe Group is 4407 m 1.0 thick at the Isleta #2 well and is underlain by 15.7 Pass intersection with Douglas Rd and 1787 m of the Eocene-Oligocene unit of prepare to stop on left (south) side of road. Isleta #2, which overlies more than 288 m of 0.2 sediments correlated with the Eocene Baca or Galisteo fms. 1.8

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Figure 2-1. Cross Section across eastern flank of Isleta volcano and the Rio Grande Valley, illustrating late Pleistocene and Holocene inset fluvial deposits and the “island” of Isleta.

15.9 STOP 2-1. Turn left and park at wide metaquartzite and various volcanic rocks dominate shoulder on south edge of road. Middle the gravel underlying this hill. Sparse Pedernal chert Pleistocene inset fluvial terrace deposit of and sandstone clasts are also recognized. Sandstone the ancestral Rio Grande (Lomatas Negras gravel is not typical of the ancestral Rio Grande Fm). Isleta 7.5’ quadrangle, GPS, NAD 83, facies and are probably remnants of an older alluvial Zone 013 S, N: 3,873,725 m; E: 341,260 m. deposit that once overlain this deposit, or the Walk to the top of the low hill on south side sandstone gravel was incorporated from the nearby of road. buttress unconformity. This deposit is about 60 m The purpose of this stop is to examine a remnant below the Sunport surface, the broad mesa about 120 of a middle Pleistocene terrace deposit of the Rio m above the Rio Grande on the eastern side of the Grande and to discuss recent work on the terrace valley. This deposit is correlated to the Lomatas stratigraphy. Negras Fm, one of the oldest definitively inset fluvial Inset stratigraphic relationships require the terrace deposits. development of bounding discontinuities along Terrace deposits were originally given deposit margins. These buttress unconformities are geomorphic names, such as Primero Alto, Segundo analogous to buried valley margin bluffs that mark Alto, and Tercero Alto (Lambert, 1968; Machette, the edge of the paleovalley. At this stop, we are less 1985). Such terms were originally defined by Bryan than 300 m east of such a remnant paleobluff line, and McCann (1936) for terraces of the upper Rio which is defined by the terminations of low spur Puerco Valley, which has a distinctly different ridges that are underlain by the Arroyo Ojito Fm. drainage morphology, and transported (sedimentary Rounded, stratified cobbles and pebbles of dominated) lithology compared to the crystalline- and

2-5 NMBGMR 454C volcanic-dominated deposits of the Rio Grande breaching of a lake within the caldera. Thus, the Valley. Lambert (1968) defined the Edith, Menaul, development of the Sunport surface is constrained and Los Duranes formations as lithostratigraphic between 0.7-1.2 Ma. units. Connell and Love (2001) proposed additional The slightly higher hills to the west are terms to round out Lambert’s stratigraphy and to exposures of the Arroyo Ojito Fm. The discontinuous avoid confusion between geomorphic and lithologic low spur ridges represent the paleobluff, or buttress terms. unconformity, between this fluvial deposit and the The oldest fluvial deposit is the Lomatas Negras upper Santa Fe Group. Fm, an early-middle Pleistocene fluvial deposit exposed at this stop. Love (1997) delineated this unit Turn left and continue on Pajarito Rd going west. 0.3 as a terrace complex because the base(s) are poorly exposed and there is a large range in the heights of the gravel beds (from ~30 to ~73 m above the floodplain), and the tops are buried by several meters of alluvium and eolian sand sheets that prograded across these terraces before erosion dissected arroyo valley fills through the terraces. Inset against the Lomatas Negras (Tercero Alto of Machette, 1985) is the Edith Fm, which is also middle Pleistocene in age. The late-middle Pleistocene Los Duranes Fm is the best-dated terrace in the area. The 156 ka Albuquerque volcanoes (U/Th date of Peate et al., 1996) is interbedded near the top of this deposit. The broad terrace tread, called the Segundo Alto by Lambert (1968) is buried by 98-110 ka flows of the Cat Hills volcanic field. The Menaul Fm is a gravel deposit found east of the Rio Grande. This deposit may be part of the Los Duranes Fm. Inset against the Los Duranes Fm is the Arenal Fm (Primero Alto surface of Lambert, 1968; also Machette, 1985), which contains a fairly weak soil with Stage I and II+ carbonate morphology (Connell et al., 1998b; Machette et al., 1997). The modern valley alluvium of the Los Padillas Fm insets this lowest terrace deposit. Figure 2-3. Stratigraphic section of the Lomatas Entrenchment of the upper Santa Fe Group is Negras Fm at an active gravel quarry in the Pajarito constrained by the Lomatas Negras Fm. This deposit grant. The Lava Creek B ash is within a thick contains a fallout ash of the ~0.66 Ma Lava Creek B succession of gravel and sand that is overlain by a (Yellowstone National Park, Wyoming and Montana) fining-upward sequence of sand and mud. These exposed in an active gravel quarry along the western fluvial deposits are overlain by a thin tongue of margin of the Valley (Isleta quadrangle), a couple of alluvial sediments derived from the western margins kilometers south of this stop (Figs. 2-3 and 2-4). This of the valley. ash, found about 35 m above the Rio Grande, was geochemically correlated to the middle Pleistocene 16.2 Note slightly higher hill to the northwest Lava Creek B (~0.66 Ma; Izett et al., 1992) (right), which exposes the Arroyo Ojito Fm separately by A. Sarna-Wojcicki (U.S. Geological in a degraded east-facing riser between the Survey) and N. Dunbar (N.M. Bureau of Geology Santa Fe Group (ancestral Rio Puerco) and and Mineral Resources). Unfortunately, continued inset fluvial deposits of the ancestral Rio quarry operations have buried or possibly obliterated Grande to the east. 0.2 this stratigraphically important ash. This terrace 16.4 Pass under powerlines. The Cejita Blanca is deposit is about 44 m below the Sunport surface, at 1:00. 1.2 which is underlain by a fallout ash of the upper 17.6 Top of hill on eastern edge of the Llano de Bandelier Tuff in Tijeras Arroyo. Boulders of upper Albuquerque. Turn left (south). Travel south Bandelier Tuff are found near the top of the ancestral on footwall of west-facing normal fault Rio Grande facies of the upper Santa Fe Group. cutting the Llano de Albuquerque. 0.6 These were probably deposited from a post-eruption

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the right (north) is the new Bernalillo County Metropolitan Detention center. Water levels from wells drilled in the area indicates about 244 m (800 ft) to water. The water quality on much of the Llano de Albuquerque is poor. At the Detention Center, it is unpotable. Water will likely have to be piped in from the city to accommodate the residents of this institution. 0.6 24.4 Bear left. 0.1 24.5 STOP 2-2. Ceja del Rio Puerco. Hike south along edge of to Stop. Dailies NW 7.5’ Figure 2-4. Photograph of fallout ash correlated to quadrangle. GPS: NAD 83, Z013 S, N: the middle Pleistocene Lava Creek B. This ash is 3,872,220 m; E: 329,510 m. within a thick succession of fluvial deposits of the The purpose of this stop is to examine the ancestral Rio Grande. Correlative fluvial deposits are stratigraphy of the uppermost gravels of the Arroyo 75-85 m above the Rio Grande at the northern end of Ojito Fm (Ceja Mbr) and the overlying soil of the the basin (Smith et al., 2001). Llano de Albuquerque. We will also discuss the geomorphic development of the Rio Puerco Valley. 18.2 Turn right (west) and descend west-facing This stop is at the Ceja del Rio Puerco of Bryan and fault scarp. Light colored hills on horizon McCann (1937, 1938), a linear escarpment that between 1:00 and 2:00 are sand dunes that defines the eastern margin of the Rio Puerco Valley formed along the western edge of the Llano (Fig. 2-5). Volcanic features of the Llano de de Albuquerque. Other features on the Llano Albuquerque are visible to the east (Fig. 2-6). de Albuquerque include Los Lunas volcano The broad faulted interfluve between the Rio at 10:00, and Wind Mesa, which is cut by a Puerco and Rio Grande valleys is the Llano de south-trending graben. Between 10:00-11:00 Albuquerque of Bryan and McCann (1938). This is Gallo Mesa, which is capped by 8 Ma surfaces marks a widespread and important local top basalt on Colorado Plateau, and lies just to the Santa Fe Group and represents the top of the west of the rift border Santa Fe fault Arroyo Ojito Fm. Kelley (1977) correlated this to the (Kelley, 1977). 0.4 Ortiz surface, which was recognized at the foot of the 18.6 Note brown Quaternary eolian sand with Ortiz Mts (cf. Stearns, 1953). Kelley (1977) extended scattered pebbles of Arroyo Ojito Fm. the Ortiz surface across much of the basin. Other Eolian sand forms a relatively continuous studies (Bachman and Mehnert, 1978; Machette, mantle on the Llano de Albuquerque 1985; Connell et al., 2000, 2001c); however, indicate surface, and covers the strongly developed that a number of surfaces in the basin are of different soil, except along its margins or near fault ages and are not correlative to the Ortiz surface. scarps, where gravels are locally exposed. Lambert (1968) recognized two distinct 0.9 constructional surfaces in his study of the 19.5 Ascend one of a number of east-facing fault Albuquerque area. Lambert recognized that the Llano scarps cut into the Llano de Albuquerque. de Albuquerque surface of Bryan and McCann 0.4 (1938) was probably older than his topographically 19.9 Descend west-sloping footwall of fault and lower Sunport surface. Machette (1985) also descend into another east-facing fault block. recognized this difference in landscape position and 0.4 age. On the basis of comparisons of pedogenic 20.2 Cross under powerline. We will take this carbonate accumulation to other better-dated areas, powerline road north to get to Stop 3. 3.2 such as the Mesilla basin of southern New Mexico 23.8 Cinder cones and flows of the middle-to (Gile et al., 1981), Machette (1985) estimated the age late-Pleistocene Cat Hills volcanic field to of the Llano de Albuquerque to be around 500 ka, the south. Twenty-three cones and seven and the Llano de Manzano (Sunport) surface was extensive lava flows, ranging in age from estimated to be about 300 ka. Geologic mapping, 250 ka to less than 100 ka, mapped by stratigraphic work, and 40Ar/39Ar dating indicates that Kelley and Kudo (1978) and Maldonado and the Llano de Albuquerque surface was formed Atencio (1998a, b). The Ladron Mts form between 2.58 Ma and 1.6 Ma and the Sunport surface the skyline to the left. The large facility to was formed between 1.2 and 0.7 Ma. These revised

2-7 NMBGMR 454C ages agree somewhat with revised age estimates of conglomerate with scattered subangular cinders is similar aged surfaces in the Mesilla basin (i.e., upper less than 2 m beneath the base of deposits that and lower La Mesa surfaces, see Gile et al., 1995). contain the Llano de Albuquerque soil (Fig. 2-9). The Soils developed on the Llano de Albuquerque are age of these pumice and cinder gravels are not better developed that the Sunport surface and exhibit known, but some of the pumice pebbles correlate an ~3-m thick Stage III+ and IV pedogenic carbonate may correlate to Pliocene age pumice gravels found morphology, such as from a trench dug near the beneath the top of the Arroyo Ojito Fm in Rio center of this surface (Fig. 2-7). This soil forms a Rancho, New Mexico and on the Isleta Reservation discontinuously exposed band along the margins of (N. Dunbar, 2001, personal commun.). 40Ar/39Ar the Llano de Albuquerque (Fig. 2-6). Soils developed dates from these pumice pebbles are pending, but on the Sunport surface commonly exhibit Stage III they are similar to other dates pumice pebbles near and III+ pedogenic carbonate morphology. The the top of the Arroyo Ojito Fm section in Rio Rancho greater antiquity of the Llano de Albuquerque surface and Isleta, New Mexico. Fluvially recycled 2.58 Ma is expressed by the presence of larger fault scarps that pumice is present the Arroyo Ojito Fm in the Rio cut the surface and the preservation of thick Grande Valley to the east. About 4 km south, along eolian/colluvial wedges adjacent to these intrabasinal the Ceja del Rio Puerco, the 3.00 Ma (Fig. 2-10; date faults. In contrast, fault scarps and associated eolian- from Maldonado et al., 1999) Cat Mesa basalt is colluvial wedges are typically shorter and thinner, overlain by about 15 m of gravel and sand of the respectively, on the Sunport surface. uppermost Arroyo Ojito Fm. These age constraints Deposits underlying the Llano de Albuquerque suggest that the Llano de Albuquerque formed closer contain cross bedded fluvial sand and gravel and to 2.5 Ma, rather than 1.6 Ma. The presence of at muddy sandstone (Fig. 2-8). Rounded chert, least 38-68 m of Arroyo Fm above this 2.58 Ma sandstone, and granite, with subordinate amounts of pumice could also indicate eastward thickening and Pedernal chert, porphyritic intermediate to slightly depositional offlap as deposits of the western margin silicic pebbles and cobbles, and scattered basalt, flowed towards the basin depocenters near the eastern dominate gravel. A bed of pumice-bearing pebble margin of the basin (see Day 1 road log).

Figure 2-5. View to east of the Llano de Albuquerque and late Pliocene and Pleistocene volcanic fields. The Manzano Mountains, in the background, mark the eastern structural margin of the rift.

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Figure 2-6. View to north along Ceja del Rio Puerco. The white band near the top of the hill is the petrocalcic soil of the Llano de Albuquerque, which is locally overlain by thick dune deposits along the edge.

The Rio Puerco Valley cut about 190 m into the Llano de Albuquerque to the east and to the south Arroyo Ojito Fm along the western margin of the (Fig. 2-12; see also Fig. 1-34). basin. The presence of ~0.66 Ma Lava Creek B ash (Izett and Wilcox, 1982) about 80 m above the valley floor indicates that this valley was cut prior to 0.7 Ma. A suite of inset, basalt-mantled surfaces are preserved by the Rio Puerco Necks (Hallett, 1990) indicate that these drainages were entrenched on the southeastern Colorado Plateau by late Pliocene time. A longitudinal profile constructed for the lower Rio San Jose (Love, 1986; modified in Love et al., 2001) also indicates Pliocene entrenchment of the Colorado Plateau since about 4 Ma (Fig. 2-11). Aggradation of the upper Santa Fe Group continued after emplacement of the 3.00 Ma (Maldonado et al., 1999) flow and deposition of 2.58 Ma pumice. Soils of the Llano de Albuquerque contain Figure 2-7. Exposure of a petrocalcic soil developed sparse, scattered pebbles that were probably moved on the Llano de Albuquerque at the Soil Amendment into the soil-profile by bioturbation. Much of the Facility (City of Albuquerque. This exposure is at the sediment in the soil is fine- to medium-grained sand east end of a trench cut across an antithetic fault to and is of likely eolian origin. Soils of the Llano de the San Ysidro (or Calabacillas) fault zone, which Albuquerque studied to the northeast indicate that was excavated by Jim McCalpin of GEOHAZ, Inc. horizons contain as much as 53% (weight percent calculation) of micritic carbonate throughout the soil The apparent lack of a thick early Pleistocene, profile (Machette et al., 1997, site 13). This thick Sunport correlative, deposits in the Rio Puerco petrocalcic soil is overlain at this stop by a 10-m Valley is puzzling. The lack of preservation of such a thick succession of eolian sand that contains at least thick deposit suggests that erosion within this three buried soils. drainage is quite effective in removing older inset Differences in height between the Llano de fluvial remnants, or that such older deposits were Albuquerque and topographically lower and younger never deposited along this reach of the Rio Puerco Sunport and Llano de Manzano surfaces are strongly Valley to begin with. controlled by intrabasinal fault that down-drop the

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Ruhe (1969) defined a geomorphic surface as “ a portion of the land surface comprising both depositional and erosional elements having continuity in space and a common time of origin. It may occupy an appreciable part of the landscape and may include many landforms. A geomorphic surface is established when a stable surface is first exposed to subaerial weathering and soil development”.

Figure 2-9. Uppermost cross bedded gravelly sandstone of the Ceja Mbr. (Arroyo Ojito Fm). A bed of pumice-bearing conglomerate is less than 2 m below the prominent white cliff of the Llano de Albuquerque petrocalcic soil (Stage IV here). Figure 2-8. Stratigraphic section along Ceja del Rio Puerco at Stop 2-2. A bed of pumice-bearing conglomerate with scattered subangular reddish- brown cinders is less than 2 m below the base of the sandstone that contains the Llano de Albuquerque (LdA) soil.

This lack of preservation of early Pleistocene deposits could be the result of sediment bypass through the valley as a result of a lack of space to accommodate the deposition of such sediment. Activity of the western basin margin faults is not well known, however, projections of Pliocene-aged deposits and volcanic units across the basin boundary Figure 2-10. The 3.00 Ma Cat Mesa basalt overlies (Fig. 2-11) suggest that little significant faulting has silty sand containing buried paleosols. This basalt is occurred since late Pliocene time. Thus, it is possible about 15 m below the Llano de Albuquerque. Florian that faulting did not provide space for significant Maldado and Dave Love are kneeling at the foot of long-term sediment storage, but rather, sediment was this flow. transported out of the Rio Puerco Valley during late Pliocene and early Pleistocene time. This problem warrants further study. Throughout the literature of the evolution of the Rio Grande one constantly sees references to surfaces, the Llano de Albuquerque, the Llano de Manzano, the Sunport surface etc. What do these surfaces represent and how do you recognize them? Every now and again you also see references to geomorphic surfaces, are they the same as the above surfaces or are they completely different?

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Figure 2-11. Longitudinal profile of the Rio San Jose from the distal end of McCartys flow to the confluence with the Rio Puerco and western edge of the Llano de Albuquerque surface (modified from Love, 1989 with date of Cat Mesa flow from Maldonado et al., 1999). Stratigraphic data indicate that the Llano de Albuquerque is younger than 3.0-2.6 Ma and older than 1.2 Ma. Major incision of the Rio San Jose after about 2.4 Ma suggests that the Llano de Albuquerque surface may have formed somewhat later, perhaps by 2.5-2.0 Ma.

Figure 2-12. Cross section across basin, illustrating structural and geomorphic relationships among the three major lithofacies assemblages. Western fluvial facies of the Arroyo Ojito Fm (undivided, To) are locally subdivided on this diagram into the Ceja Mbr (Toc) and Atrisco unit (Toa, of Connell et al., 1998a). Deposits of the axial Rio Grande (QTsa) and younger (QTsp) and older (Tsp) piedmont facies are east of the Rio Grande deposits. Pre-rift deposits include Paleocene mudstone (T, Thomas et al., 1995), Pennsylvanian limestone and Proterozoic crystalline rocks.

By this definition a geomorphic surface is Transformation of geomorphic surfaces by erosion or recognized by the development of a soil profile and it deposition results in the formation of new is a time . The duration of stability is geomorphic surfaces. The intergrade elements of this represented by the degree of soil development. continuum are described as degradation and Because of the need to recognize the spatial aggradational phases of the present geomorphic continuity of erosional and depositional elements the surface. These phases are recognized where the soil following terms are used: Buried Geomorphic profile has been modified by degradation exposing B- surfaces are parts of former geomorphic surfaces now horizons or aggradation thickening the surface buried and underlying the present geomorphic horizons (Tonkin et al., 1981). surface. Exhumed geomorphic surfaces are former The Llano de Albuquerque and Llano de geomorphic surfaces now re-exposed by erosion. Manzano surfaces as commonly applied in the

2-11 NMBGMR 454C literature refer to top of the Santa Fe Group gravels, near its mouth at the front of the Sandia marking the last basin-wide aggradational fill prior to Mountains. Deposits derived from the the incision of the Rio Grande Valley in early Tijeras Arroyo drainage basin are more Pleistocene time. Since this time the surface of these heterolithic than alluvium derived from the fluvial deposits has been exposed to a wide range of western front of the Sandia Mts, which surficial processes, including significant faulting contains mostly granite, schist, and minor (Machette 1985; McCalpin, 1997) fan progradation limestone. 0.4 from adjacent hillslopes and sand sheet deposition. 41.1 Turn left (east) onto Bobby Foster (Los There are probably very few parts of the original Picaros) Rd. 0.5 surface existing today and it is unlikely that there are 41.6 Turn right (south) at junction with Los soil profiles that date from that time period and are Picaros Rd. Drive uphill towards the Journal unaltered by surficial processes. The wide variety of Pavilion. Ascend deposits of the Arroyo soil profiles described on these surfaces reflects Ojito Fm. White bed at 2:00 on west side of different-aged geomorphic surfaces. This is also true I-25 is within the Arroyo Ojito Fm. This bed of the incised terrace treads such as the Sunport contains a recently discovered surface. Thus the bottom line is that soil development microvertebrate site of probable medial cannot be used to identify the Llano de Albuquerque, Blancan age (Pliocene; G. Morgan, 2001, Llano de Manzano or the Sunport Surfaces. personal commun.). 0.8 42.4 Top of hill. Pale beds on top of the mesa Turn around and retrace route to intersection contain Stage III+ soils of the Sunport of road and powerline at mile marker 20.2. surface, which is developed on a west- 3.9 thinning wedge of pumice-bearing deposits 28.4 Turn left (north) at road just east of of the ancestral Rio Grande. The early powerlines. Note prominent west-facing Pleistocene ancestral Rio Grande fluvial fault scarp to your right (east). 2.8 system extended at least 7 km east of here 31.2 Turn right (east) onto Senator Dennis 0.6 Chavez Rd. 1.0 43.0 Disturbed area around road is reclaimed 32.2 Descend into valley of the Rio Grande. South Broadway landfill, which Deposits of the Arroyo Ojito Fm locally intermittently operated as an unlined exposed in spur ridges. Valley border fans municipal landfill between 1963-1990. 0.4 are incised into the Los Duranes Fm and 43.4 View of range-bounding eastern margin of overlie the Arenal Fm. 2.2 the Albuquerque Basin. The Sandia Mts at 34.4 Flat surfaces underneath housing 10:00-12:00, Four Hills salient of the Sandia development is the Primero Alto surface and Mts at 12:00, the flat-topped Manzanita Mts underlying Arenal Fm, a late Pleistocene at 12:00-2:00, and the higher Manzano Mts fluvial deposit of the ancestral Rio Grande to the south. Tijeras Canyon, one of the that is inset against the middle Pleistocene largest rift-border drainages in the area and Los Duranes Fm. 0.4 the namesake drainage of Tijeras Arroyo, 34.8 Crossing onto floodplain of the Rio Grande. enters the basin at about 12:00. Scarps of the Road is built on fill over this deposit. 0.6 Hubbell Spring fault zone extend south from 35.4 Cross Coors Blvd. Continue straight (east) the Four Hills. 0.8 where road becomes Rio Bravo Blvd. (NM- 44.2 Large excavations to your right (east), 500). 1.9 locally known as the “Suez canal,” expose 37.3 Cross Isleta Blvd (NM-314). Continue east the Sunport soil and overlying eolian and descend into yazoo along eastern margin deposits. 0.3 of valley. 1.8 44.5 STOP 2-3. Pull off road onto shoulder at 39.1 Ascend valley border alluvium, which north end of 3.3 m deep pit. Sunport surface. prograded over the Rio Grande floodplain. Albuquerque East 7.5’ quadrangle: GPS, Prepare to turn right. 0.2 NAD83, Z 013 S, N: 3,874,245 m; E: 39.3 Turn right (south) onto South Broadway 352,010 m. (NM-47). Mesa to left (east) is the Sunport At this stop we will examine soils of the early surface and the Albuquerque International Pleistocene Sunport surface, which is commonly Airport (a.k.a. Sunport). 1.4 overlain by a thick accumulation of eolian sand (Fig. 40.7 Driving on the sandy alluvium of Tijeras 2-13). The Sunport soil is about 1.6 m thick and Arroyo. This arroyo contains a mixture of commonly exhibits a strongly developed Stage III+ granite, greenstone, gneiss, and sandstone carbonate morphology. Strongly developed platy

2-12 NMBGMR 454C structure is also present in the strongest developed Park. Check in with Open-Space division parts of the soil profile. The top is irregular, eroded, before proceeding east. Drive east towards and is overlain by about 1.6 m of eolian sand with metal warehouse buildings near end of weakly to moderately developed soils and is complex. 0.1 Holocene to latest Pleistocene (?) in age. This soil is 49.8 STOP 2-4. Southeast corner of Kaibab developed on loose sand and pebbly sand of the Warehouse #1. Hydrocompactive soils. ancestral Rio Grande, which is less than 1 m below Albuquerque East 7.5’ quadrangle: GPS, the base of this detention pit. NAD 83, Z 013 S, N: 3,876,195 m; E: 354,435 m. Hydrocompactive or collapsible soils lose a significant amount of volume through reduction of porosity when wetted. Hydrocompactive sediments are typically composed of poorly sorted fine-grained sand with minor amounts of silt or clay that were deposited by debris- or hyperconcentrated flows. These deposits typically occur on geologically young, gently sloping alluvial-fan, alluvial-slope, or valley- fill environments that have not been saturated since deposition. Hydrocompactive soils have damaged roads, utility lines, and buildings, such as the Kaibab Warehouse #1 (Fig. 2-14) in several parts of New Mexico (see Haneberg, 1992). Figure 2-13. Recently constructed flood detention pit Before collapse, the soil structure of these on east side of Journal Pavilion parking lot. The deposits is porous and has relative low unit weights Sunport soil is about 1.5 m thick and exhibits Stage (typically less than 16 kN/m3) and high void ratios III+ carbonate morphology. The top of the soil is (typically higher than 1.0). Upon wetting, these irregular and has been modified by relatively deep deposits typically disaggregate and compact. Because pipes developed into the profile. of the geologic age and setting, geologic mapping can be used to predict where such soils may be present. Turn around and leave Journal Pavilion parking area Geologic mapping of the eastern part of the and head towards intersection of Los Picaros and Albuquerque metropolitan area north to Bernalillo, Bobby Foster Rds. 0.5 New Mexico (Connell, 1997, 1998; Connell et al., 45.0 Northern Hubbell bench, and site of stop 2 1995; 1998b) and evaluation of available of the day 1 field trip at 10:00-11:00. The geotechnical data suggests that the Holocene-latest numerous buildings at the foot of the Pleistocene arroyo and valley border alluvial deposits Manzanita Mts and Four Hills salient are are particularly susceptible to hydrocompaction. part of Sandia National Laboratories. 2.0 Future studies will attempt to produce predictive 47.0 Cross intersection with Bobby Foster Rd. hydrocompaction susceptibility maps. Continue straight. 0.8 At this stop, we see damage caused by 47.8 Steep-walled arroyo of Tijeras Creek. About hydrocompactive soils. This building was constructed 2 m below the surface is a zone containing on about 24 m (80 ft) of poorly sorted sand and mud abundant charcoal. A sample was of Tijeras Arroyo. Note the circular cracks in the radiocarbon dated at about 4550 yr. BP. 0.4 asphalt road around a patch of bare ground that was 48.2 The exposures to your right (south) contain presumably used to drain surface runoff from roads, gray gravel and sand of the ancestral Rio buildings, and water from a fire hydrant. The Grande deposits, which overlie brown sand concentration of runoff into this patch of bare ground of the Arroyo Ojito Fm. The underlying caused collapse of the surrounding soil and Arroyo Ojito deposits commonly contain foundation, resulting in distress to the warehouse carbonate-cemented sandstone and building. Seargent, Hauskins and Beckwith, and rhizoconcretionary intervals. 1.3 Woodward-Clyde studied the Montessa Park facility 49.5 Off-road vehicle recreation area to the south. in 1983 and 1973, respectively (Seargent, Hauskins, 0.1 Beckwith, 1983). They drilled cores and measured 49.6 Pass intersection with Ira Specter Road. the amount of consolidation, before and after wetting Keep straight. 0.1 of the sample, under differing static loads (Fig. 2-15). 49.7 Pass through gate onto Albuquerque Open- The combined results of this study indicate the Space Division Headquarters at Montessa presence of hydrocompactive deposits down to the

2-13 NMBGMR 454C level of groundwater saturation under high loads. subsidence, based on elevation differences between Under in situ loads, hydrocompaction of up to 5% the north and south edges of the building, indicate was reported to a depth of about 18 m. Should the that this structure has undergone approximately 0.6- entire column of sediment at this site become 0.8 m of deformation, mostly on the southern four saturated, the total consolidation would be about garage bays. These would be maximum estimates 5.5% and would represent a subsidence of about 1.3 because they assume total saturation of the sediment m at in situ loads. The addition of greater loads, such column, which would create other geotechnical as a multi-story building, would increase this problems, and they also ignore effects of grain subsidence at the more hydrocompactive shallow end bridging of the soil column at depth. of the sediment column. Estimates of ground

Figure 2-14. Photograph of the south end of the Kaibab Warehouse #1 facility at Montessa Park. Note the arcuate cracks in the asphalt, which have been repaired. These cracks encircle the exposed soil to the left of the building. The doors of this warehouse are out of plumb and rest on the foundation along the right side, but are not supported to the left. Dave Love is at right side of photograph.

Turn around and leave Montessa Park 60.9 Crossing contact between fluvial deposits facilities. 0.1 and overlying piedmont- and eolian- 50.4 Pass through gate. 0.6 dominated deposits of the Sierra Ladrones 60.0 Turn hard left towards Albuquerque Fm. Section contains at least 3 calcic soils. National Speedway. 0.4 Top of hill is capped by a Stage III+ soil. 0.5 60.4 Exposures of pumice-bearing fluvial deposits of the ancestral Rio Grande to the south are lower in elevation relative to deposits of the Arroyo Ojito Fm at the mouth of Tijeras Arroyo. 0.5

2-14 NMBGMR 454C

Gravel was compared among the three lithofacies assemblages. Strong clustering is recognized in comparisons of chert and metaquartzite to sandstone, volcanic, and plutonic/metamorphic constituents (Fig. 2-17). The western fluvial lithofacies assemblage (Arroyo Ojito Fm) contains abundant volcanic tuff, fine-grained red granite, sandstone, and Pedernal chert, whereas the ancestral Rio Grande lithofacies contains abundant volcanic tuffs and well-rounded metaquartzite clasts. These metaquartzite clasts are white, gray, pink, or bluish- purple and are often bedded. Although granites, sedimentary rocks, and Pedernal chert can be found in ancestral Rio Grande deposits, they are not common. Piedmont deposits contain abundant crystalline (plutonic/metamorphic) and sedimentary clasts, and generally lack volcanic detritus in the study area. Chert comprises between 30-60% of the western fluvial lithofacies, and about 2-8% of the axial-fluvial deposits. Metaquartzite is almost entirely composed of the well-rounded metaquartzite variety, comprises between 30-85% of the axial- fluvial lithofacies. In contrast, metaquartzite is a minor constituent of western-fluvial deposits. Volcanic gravel is nearly absent in the eastern- piedmont lithofacies, but is abundant in the western- fluvial and axial-fluvial assemblages. Sedimentary clasts (mostly sandstone) comprise about 35-40% of the western-fluvial lithofacies gravel, but are nearly absent in the axial-fluvial assemblage. Sandstone is locally recognized along the margins of the axial- fluvial assemblage, but only comprises a minor component of those deposits. The absence of the sedimentary component within the piedmont lithofacies in the study area is related to the Figure 2-15. Plot of percent consolidation of cored composition of drainage basins that originate on the sediment upon saturation with water. From technical footwall uplifts of the Sandia and Manzanita Mts. report by Seargent, Hauskins & Beckwith (1983) Plutonic/metamorphic gravel is present in the axial- fluvial and western-margin deposits in similar 61.4 STOP 2-5. Crest of hill. Turn around and proportions and comprises the bulk of the piedmont park on right (east) side of road. Walk composition in the study area; however, sedimentary toward borrow pit to at northeast part of gravel is a dominant constituent elsewhere along the road. Near eastern pinchout of eastern- piedmont, indicating that the lithologic composition margin piedmont deposits over ancestral Rio of eastern-margin drainages depends upon on Grande. Albuquerque East 7.5’ quadrangle: composition of upland drainages. GPS, NAD 83, Z 013S, N: 3,875,250 m; E: Discrimination among lithofacies assemblages is 354,345 m. best expressed in the ternary relationship among Recent unpublished geologic mapping of Tijeras chert-metaquartzite-plutonic/metamorphic and chert- Arroyo (Fig. 2-16) delineates the presence of metaquartzite-sedimentary rocks (Figs. 2-17). The western-fluvial, axial-fluvial, and eastern-piedmont field of variation for two standard deviations, around deposits. Gravel from these three major lithofacies the mean composition, indicates no overlap of the assemblages have been studied and indicate that three lithofacies assemblages if chert and comparing the proportions of metaquartzite can quite metaquartzite are compared to sandstone and easily differentiate among these facies, as can volcanic constituents. Strong clustering is also comparisons to chert to sandstone, volcanic, or observed in comparisons of chert-metaquartzite- crystalline rocks (Fig. 2-17). volcanic and to a lesser extent when chert and

2-15 NMBGMR 454C metaquartzite are combined. The weakest clustering makes up a large component of the western-fluvial occurs where chert+metaquartzite as compared to lithofacies assemblage. other constituents in the absence of the sedimentary component. This is because sedimentary detritus

Figure 2-16. Simplified geologic map of Tijeras Arroyo and vicinity (modified from Connell et al., 1998b; Connell, unpubl.; Maldonado et al., in prep.).

2-16 NMBGMR 454C

Figure 2-17. Ternary discrimination diagrams of detrital modes of gravel from stratigraphic localities in the southern Albuquerque and Isleta areas. Solid squares, circles, and diamonds indicate western fluvial, axial-fluvial, and eastern piedmont lithofacies assemblages, respectively. The open square, open circle, and “x” denote the mean of the western fluvial, axial-fluvial, and eastern piedmont lithofacies assemblages, respectively. The “+” and open diamond indicate compositions of younger inset (post-Santa Fe Group) fluvial deposits of the ancestral Rio Grande, and Tijeras Arroyo alluvium, respectively. Comparisons of chert (Qc) and quartzite (Qq) to plutonic/metamorphic (Pm) (a) and sandstone (S) (b) constituents indicate the strongest clustering. Comparisons of chert and quartzite to volcanic (V) constituents (c) indicates some overlap of fields of variation.

The spatial variations of lithofacies assemblages in Tijeras Arroyo indicate progradation of the eastern-margin piedmont over the ancestral Rio Grande deposits. Eastern piedmont deposits, which are quite sandy at this stop, pinch out into sandstone about 1.5 km to the west, between TA1 and TA2 (Fig. 2-18). Multiple soils exposed at this site merge into a single soil less than 1.5 km to the west. Stratigraphic relationships at this stop support the presence of a progradational wedge of early Pleistocene sediment that onlaps onto older sediments of the Arroyo Ojito Fm. Drillhole data also do not support the presence of a buttress unconformity bounding the eastern side of a 6-10 km wide early Pleistocene fluvial terrace as proposed by Cole et al. (2001a, b) and Stone et al. (2001a, b).

Drive towards mouth of Tijeras Arroyo at Bobby Foster-Los Picaros intersection. 3.6 65.0 Turn right (west) onto Bobby Foster Rd. 0.2 65.2 Note abundant anthropogenic auto-recyclic deposits at mouth of Tijeras Arroyo. 0.4 65.6 Turn right (north) onto South Broadway (NM-47). 0.7 66.3 Turn right (east) onto long dirt driveway at 4500 Broadway SE. The gate may be locked. 0.1 66.4 Pass through gate. 0.2

2-17 NMBGMR 454C

Figure 2-18. Fence diagram of stratigraphic sites for Day 2. Horizontal distances are not to scale. Note westward progradation of eastern-margin piedmont and ancestral Rio Grande deposits. The eastern thickening wedge of piedmont deposits are interpreted from drillhole data from wells on the Sandia National Laboratories. Some of the lithologic interpretations are constrained by sandstone petrography, which shows the proportions of sandstone (SRF), volcanic (VRF), and metamorphic (MRF) rock fragments in these wells (Thomas et al., 1995). The piedmont facies here contain no volcanic detritus, therefore the presence of such material indicates ancestral Rio Grande or Arroyo Ojito sediments. Because of the location of these wells near the eastern side of the basin, the deposits are likely ancestral Rio Grande.

66.6 STOP 2-6. Gravel quarry near mouth of interpreted to be inset against older non-pumiceous Tijeras Arroyo. Walk to northern margin of deposits of the ancestral Rio Grande (Cather and Tijeras Arroyo along Railroad tracks. Park McIntosh, 1990). Later work, however, demonstrated on north side of gravel quarry. Albuquerque that this relationship was the result of faulting, and West 7.5’ quadrangle, GPS, NAD 83, UTM not due to Plio-Pleistocene entrenchment (Dunbar et Zone 013 S; N: 3,875,400 m; E: 345,000 m. al., 1996, p. 70). Lucas et al. (1993) note the presence Walk east to abandoned railroad tracks and of pumice low in the section that may have under the I-25 overpass to examine the represented this unconformity at Tijeras Arroyo. The nature and stratigraphic context of the lowest exposure of pumice in the section would contact between the axial-fluvial Rio Grande presumably mark the onset of early Pleistocene and underlying Arroyo Ojito Fm. sedimentation (i.e., contains clasts of Bandelier Tuff). Lucas et al. (1993) measured a section at the However, the presence of Pliocene-age pumice mouth of Tijeras Arroyo to document the pebbles in the Arroyo Ojito Fm (see Stop 2-2) stratigraphic positions of a Pliocene (medial Blancan) indicates that caution must be used in determining and numerous early Pleistocene (early Irvingtonian) age and provenance on the basis of pumice clasts as fossil localities exposed in the arroyo. They the sole criterion. suggested the possibility of an unconformity in this Geologic mapping and preliminary results of section, based mainly on absence of late Blancan gravel and sand petrography indicate that the lower fossils and because of an inferred unconformity part of the succession at this stop is correlative to the between Pliocene and lower Pleistocene fluvial Arroyo Ojito Fm (Fig. 2-16, 2-17; Connell et al., sediments near San Antonio, New Mexico (Cather 1998b; Connell and Derrick, unpubl. data). Deposits and McIntosh, 1990), in the Socorro Basin, about 140 of the Arroyo Ojito Fm contain sparse scattered km to the south. At San Antonio, exposures of pumice pebbles and are overlain by pumice-bearing pumice-bearing ancestral Rio Grande deposits at the sand and gravelly sand deposits of the ancestral Rio Bosquecito pumice site contain pumice of the lower Grande that are about 20 m below the Sunport Bandelier Tuff. This deposit was originally surface. Tephra in this upper succession are

2-18 NMBGMR 454C correlated to the early Pleistocene Bandelier Tuff and An examination of exposures in Tijeras Arroyo Cerro Toledo Rhyolite (Jemez volcanic field) and (Fig. 2-18) indicates that the Arroyo Ojito/Sierra were laid down by the ancestral Rio Grande during Ladrones contact dips to the east and ancestral Rio early Pleistocene time. These stratigraphically higher Grande deposits thicken appreciably to the east. Age deposits contain early Irvingtonian (early constraints in the upper part of the Arroyo Ojito Fm Pleistocene) mammals (Lucas et al., 1993). The are poor, but the presence of a fluvially recycled ancestral Rio Grande deposits contain more abundant pumice at 2.58 Ma indicates that the upper part of the rounded quartzite than the underlying deposits, which Arroyo Ojito section is younger than 2.58 Ma. Early contain abundant chert and sandstone clasts. An ash Pleistocene deposits of the ancestral Rio Grande dated at 1.26 Ma is several meters below the top of overlie these deposits. Stratigraphic relationships the ancestral Rio Grande section in an exposure along strongly suggest the presence of an unconformity the southern margin of Tijeras Arroyo. between these two deposits, which is consistent with During repeated reconnaissance of Tijeras angular relationships between these units observed Arroyo between 1998-2001, we mapped the geology near faults to the south (Fig. 2-20). of the arroyo and re-measured the stratigraphic Studies of gravel composition (Fig. 2-17) and the section of Lucas et al. (1993; Fig. 2-19). Five discovery of this medial Blancan fossil locality additional stratigraphic sections supplemented this support the presence of an unconformity as section in order to document lateral variations in speculated by Lucas et al. (1993); however, this facies (Fig. 2-18). Lucas et al. (1993) recognized, but probable unconformity is stratigraphically higher (at did not differentiate, two distinct facies in this the unit 9/8 contact in TA0, Fig. 2-19) than their section. We concur with their observation and have reported lowest occurrence of pumice in the section differentiated these facies on our stratigraphic (unit 3 of Lucas et al., 1993). The stratigraphically column. At the mouth of Tijeras Arroyo, early lower pumice pebbles are likely correlated to the Pleistocene-aged, pumice-bearing sand and gravel of suites of Pliocene-aged pumice pebbles found in the the ancestral Rio Grande (Sierra Ladrones Fm) Arroyo Ojito Fm to the south and west, rather than overlie deposits of the Arroyo Ojito Fm. being associated with the early Pleistocene Bandelier Comparisons of these two sections indicate Tuff. significant discrepancies (Fig. 2-19). With the help of Spencer Lucas, we correlated units of the Lucas et al. (1993) section into our recent profile. Comparisons of these marker beds indicate that the overlying Sierra Ladrones Fm is much thinner than portrayed by Lucas et al. (1993). This discrepancy is likely due to mis-correlations of fine-grained marker beds and associated fossil localities into this section and facies variations. A rich mammalian fossil locality was recently discovered by S. Connell along the southern margin of Tijeras Arroyo at a road cut along I-25. Preliminary studies of this locality indicate a likely medial Blancan age (G. Morgan, 2001, personal commun.). This fossil-bearing unit projects to unit 4 of Lucas et al. (1993), which is stratigraphically higher than the unit 2-3 contact of Lucas et al. (1993) (Fig. 2-18). Aside from the distinctive lithologic changes in the section, there is little evidence for a major Figure 2-19. Comparison of stratigraphic sections unconformity or scour in these exposures. Deposits measured at the same location at the northern mouth of the underlying Arroyo Ojito Fm do not contain of Tijeras Arroyo. Left: stratigraphic section TA0. strongly developed paleosols, however, pauses in Right: Stratigraphic section of Lucas et al. (1993). sedimentation may be inferred by the presence of Paleocurrent data from the top of the exposed Arroyo locally extensive cemented sandstone intervals and Ojito Fm indicates flow to the south-southeast. rhizoconcretionary mats. The lack of a buried pedogenic counterpart to the Llano de Albuquerque suggests that some erosion of the top of the Arroyo Ojito Fm has occurred in the Tijeras Arroyo area.

2-19 NMBGMR 454C

Figure 2-20. Cross section between Rio Bravo Blvd and Hell Canyon Wash showing southward apparent dip of Arroyo Ojito Fm and the preservation and southward thickening of ancestral Rio Grande deposits. Angular unconformity beneath thin ancestral Rio Grande deposits between Tijeras and Hell Canyon arroyos is due to erosion of an intrabasinal horst block. About 100 m of sediment is preserved between 2.7 Ma and 1.6 Ma tephras. About 12- 45 m of ancestral Rio Grande deposits that post-date emplacement of a Cerro Toledo Rhyolite ash (~1.55 Ma) are exposed at the mouth of Hell Canyon Wash. This cross section is sub-parallel to faults (shown as bold lines), which have shallow apparent dips.

This unconformity, however, is probably not developed the present valley. This hypothesis is associated with a Plio-Pleistocene entrenchment currently being tested by additional field work and event, but rather may represent progressive westward dating. onlap of axial-river facies. Drillhole data to the east Westward progradation of axial-fluvial and of the Tijeras Arroyo measured sections do not eastern-margin piedmont deposits is recognized along support the presence of any significant buttress most of the eastern margin of the basin from Isleta unconformity between the pumice-bearing ancestral Reservation to north of San Felipe Pueblo, about 45 Rio Grande deposits and older basin fill (see Fig. 2- km to the north. Exposures of western, axial, and 18). This interpretation is supported by studies of the eastern facies are well exposed in the southern Santo Sandia National Labs by GRAM Inc. and William Domingo sub-basin, near San Felipe Pueblo (Fig. 2- Lettis and Associates (Thomas et al., 1995) that 21). Pliocene basaltic flows of Santa Ana Mesa and document interfingering of axial-river and piedmont various fluvially recycled and primary tephra deposits in the subsurface. The age and stratigraphic constrain the ages of deposits. Stratigraphic sections significance of such intraformational unconformities measured on San Felipe Pueblo document the is still ambiguous, but ongoing work on the presence of lithologically indistinguishable pre-2.58 biostratigraphy and pumice pebble correlation should Ma and pre-1.55 Ma vintage ancestral Rio Grande constrain this. deposits. No unconformities are recognized in the Deposits of the Sierra Ladrones Fm prograde section; however, deposits of the ancestral Rio westward and overlie this unconformity with the Grande appear to pinchout to the west and probably underlying Arroyo Ojito Fm. Although the buried only part of the eastern edge of the ~1.77-2.58 stratigraphically significant relationships are buried Ma flows of Santa Ana Mesa (Fig. 2-22). to the east by Pleistocene fluvial deposits of the A significant problem with defining the end of ancestral Rio Grande, the geometry of these basin aggradation is presented in attempting to sediments suggests westward onlap of the Rio correlate unconformities formed along the basin Grande over eroded remnants of the Llano de margin, on the up-dip portions of half-graben or Albuquerque. With few exceptions, deposits of the asymmetric basins into basin depocenters (see ancestral Rio Grande are not present west of the Rio Connell et al., 2001c). Differentiation of stratal Grande Valley, but are quite thick to the east. The discontinuities within deposits of the ancestral Rio location of the Rio Grande Valley could be explained Grande would be ambiguous at best, and arbitrary at by westward progradation of eastern-margin worst. piedmont deposits and onlap of the Rio Grande during early Pleistocene. During this westward onlap, the Rio Grande entrenched into older basin fill and

2-20 NMBGMR 454C

Figure 2-21. Simplified geologic map of the southeastern Santo Domingo sub-basin, illustrating locations stratigraphic sections in San Felipe Pueblo. Compiled from Cather and Connell (1998), Cather et al. (2000), Connell, (1998), Connell et al. (1995), and unpublished mapping.

Pre-Pleistocene deposition of the ancestral Rio The earliest documented appearance of a probable Grande is well documented in southern New Mexico, ancestral Rio Grande deposits in the Albuquerque where the earliest appearance is between 4.5 to ~5 Basin is near the northern end at Tent Rocks, where Ma (Mack et al., 1996; Mack, 2001). In the San metaquartzite-bearing pebbly sandstone is associated Felipe area, gravel-bearing ancestral Rio Grande with 6.9 Ma tephra of the Peralta Tuff of the deposits are recognized beneath the 1.77-2.58 Ma Bearhead Rhyolite (Smith et al., 2001). basalts on the southeastern flank of Santa Ana Mesa.

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Figure 2-22. Fence diagram on San Felipe Pueblo illustrating stratigraphic relationships among western-fluvial, axial-fluvial, and eastern-margin piedmont deposits (Derrick and Connell, 2001; Derrick, unpubl. data). Santa Fe Group deposits pinchout onto the eastern edge of Santa Ana Mesa. See Figure 2-22 for locations of sections.

If incision of basin fill is climatically driven, speculate that this early Pleistocene entrenchment then the proposed late Pliocene entrenchment might be climatically driven. However, there is little proposed by Stone (2001a, b) and Cole (2001a, b) evidence for the presence of a regional climatically should be regional in nature. Comparisons of the induced unconformity in these basins. These basins stratigraphy of the Albuquerque Basin with tend to coarsen upsection, suggesting that the radioisotopically and paleomagnetically well dated increased caliber of sediment might be attributed to comparable successions of the southern Rio Grande climate, which presumably became more competent rift (Fig. 2-23; Mack et al., 1993, 1996; Mack, 2001) during the late Pliocene. The nature of these indicate the presence of nearly continuous stratigraphic changes will no doubt be of continued aggradation until about 800 ka, when the Rio Grande interest and study. Valley cut. In the tectonically quiescent part of a Return to NM-47. End of Day-two road log. southern Basin and Range in southeast Arizona, Smith (1994) documents basin aggradation of the St. David Fm during Pliocene and early Pleistocene times (Fig. 2-23). Thus, it seems reasonable to

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Figure 2-23. Comparison of upper Pliocene and lower Pleistocene alluvial successions in the southern Rio Grande rift, New Mexico, and southeastern Arizona (Smith, 1994; Mack et al., 1993, 1996; Connell, Love, Derrick, unpubl. data). The earliest documented occurrence of the ancestral Rio Grande may be as early as 4.5 or ~5 Ma in southern New Mexico (Mack et al., 1996; Mack, 2001). Entrenchment of the Santa Fe Group is recorded by development of the Rio Grande Valley and the development of constructional surfaces, such as the lower La Mesa surface in southern New Mexico. Aggradation of the St. David Fm is recorded in a tectonically quiescent basin in southeastern Arizona to ~0.6 Ma.

2-23 NMBGMR OFR454C TH FRIENDS OF THE PLEISTOCENE, ROCKY MOUNTAIN CELL, 45 FIELD CONFERENCE

PLIO-PLEISTOCENE STRATIGRAPHY AND GEOMORPHOLOGY OF THE CENTRAL PART OF THE ALBUQUERQUE BASIN

THIRD-DAY ROAD LOG, OCTOBER 14, 2001

Geology of Los Lunas volcano

DAVID W. LOVE New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

SEAN D. CONNELL New Mexico Bureau of Geology and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, New Mexico 87106

The following trip presents an overview of the regional setting of Los Lunas volcano(es), some history of geologic work in the area, results of recent geochemistry and geochronology of the eruptives, the relation between the volcanoes and basin fill, deformation associated with the volcanoes, and post-eruption erosion and piedmont deposition. The trip consists of a drive from Isleta Lakes to the flanks of El Cerro de Los Lunas where some vehicles will be parked and orientation/background presented. High clearance vehicles will shuttle the group higher onto the side of the volcano and the group will hike down into a steep canyon and back to the lower vehicles. Along the way the group can examine two spectacular angular unconformities between three packages of basin fill, a disconformity at the base of San Clemente graben-fill, Pliocene fluvial beds with pumice, obsidian, and Blancan fossils, thick and thin-skinned deformation involving tephra of Los Lunas volcano, and post-eruptive piedmont and eolian deposits with multiple soils. Permission from the Huning Land Trust in Los Lunas must be obtained before attempting this trip apart from the Friends of the Pleistocene, October 14, 2001. Colleague-contributors who helped advance knowledge of the volcano and deserve acknowledgement and thanks (but bear no blame for the field trip leaders mistakes): Charles Reynolds, John Hawley, Rick Lozinsky, Nelia Dunbar, Bill McIntosh, Bruce Hallett, Kurt Panter, Chris McKee, John Young, Bert Kudo, Bill Hall, Jacques Renault, Jim Casten, Becky Thompson, Tad Niemyjski, Bill Haneberg, and Tien Grauch.

Mi. Description are associated with the last 0.0 Isleta Lakes Store. Follow previous road incision/aggradation episode of the Rio logs to NM 47 and I-25 south. 0.4 Grande. Incision probably occurred during 0.4 Cross railroad; golf course on right. 0.5 latest-Pleistocene time, and entrenched 100 0.9 Stop light with NM-47. Turn left and keep m below the highest inset terrace deposit of in left lane. Prepare to turn left. 0.5 the Lomatas Negras fm. 0.6 1.4 Cross under I-25 overpass, keep in left lane. 4.4 Crossing bridge over Old Coors Road, 0.2 which follows a former course of the Rio 1.6 Turn left and head south on NM-47 (South Grande cut through the lava flow of Black Broadway). 0.1 Mesa. Roadcut to right shows the edge of 1.7 South Broadway. Get into right lane. 0.1 the 2.68±0.04 Ma (40Ar/39Ar, Maldonado et 1.8 Turn right onto southbound I-25 entrance al., 1999) Black Mesa flow overlying cross- ramp. 0.3 bedded pebbly sands of the Arroyo Ojito Fm 2.1 Merge with I-25 south (headed west). 0.5 and base-surge deposits from Isleta volcano. 2.6 East abutment of I-25 bridge over Rio The tholeiitic Black Mesa flow has no Grande. Rio Grande channel ahead. 0.4 outcrop connection with, and is slightly Milepost 214. West bridge abutment. 0.5 younger than Isleta volcano, which forms 3.5 Entering Isleta Reservation. Overpass of the dark, rounded hill ahead and to the right drain and location of Isleta-Black Mesa of the highway. A buried vent for the Black piezometer, which encountered 73 ft (22 m) Mesa flow is suspected in the floodplain of sandy fluvial deposits underlying the Rio area to the northeast (Kelley et al., 1976; Grande floodplain (Los Padillas Fm of Kelley and Kudo, 1978). 0.3 Connell and Love, this volume). Deposits

3-1 NMBGMR OFR454C ELEVATIONS OF GEOLOGIC FEATURES, WIND MESA, ISLETA, MESA DEL SOL (SOUTH), BETWEEN I-25 MILE POSTS 212 AND 210 Elevations are in feet above mean sea level as measured from USGS 7.5-minute topographic maps Arrows point to described features and elevations to your left (east) and right (west) in decreasing order of elevation. EAST WEST top of east horst of Wind Mesa 5730Æ “bath-tub ring” of gravel, east side of Wind Mesa 5500 Æ top of Isleta volcano 5387 Æ Å 5340 base of Western Hubbell Spring fault scarp Å 5240 top of Mesa del Sol east edge of Llano de Albuquerque (down-faulted block) 5240 Æ Å 5230 top of gravel with Bandelier boulders Å 5210 base of Rio Grande gravelly sand capping Mesa del Sol Å 5205 tilted Arroyo Ojito Fm under Mesa del Sol containing Pliocene pumice Å 5195 Pliocene Isleta (?) basaltic tephra in Arroyo Ojito Fm; 1.58 Ma pumice overlying it. Å 5130 local top of Pliocene thick reddish-brown sandy clay of Arroyo Ojito Fm top of upper terrrace gravel west of Isleta volcano 5100 Æ Å 5050 base of thick reddish-brown clay (Pliocene) of the Arroyo Ojito Fm upper edge of lava lake within tuff ring 5050 Æ top of Los Duranes Fm 5020 Æ Å 4960 Pliocene pumice gravel top of Rio Grande terrace inset against Isleta volcano 5000 Æ basaltic edifice southeast of Isleta volcano with strath terrace at top 4910-4970 Æ base of Rio Grande terrace inset against Isleta volcano 4910 Æ Å 4910 Pliocene pumice gravel 1.68 Ma Base of lava flow east of Highway 85, 4900 Æ Å 4885 Isleta (?) tephra 4895 Æ Å 4892 Pliocene pumice gravel Å 4890 Rio Grande flood plainÆ Å 4885 Rio Grande floodway channel Æ Å 4805 base of Rio Grande paleovalley Æ

4.7 Base-surge deposits of tuff cone associated de Albuquerque was abandoned as an active with emplacement of Isleta volcano in fluvial fan prior to deposition of Lower outcrops on both sides of route. 0.5 Bandelier ash and pumice gravel at ca. 1.6 5.2 Change in primary dip direction of base- Ma. Locally, the cinders of Isleta Volcano surge deposits at crest of tuff ring on right. on the east side of the valley have Overlying alkali-olivine basalt flows fill tuff experienced over 100 m of uplift with ring and extend southeast beyond Isleta consequent erosion of the overlying units volcano. Radioisotopic dates (40Ar/39Ar before final deposition by the Rio Grande to method) indicate that oldest flow is form the Sunport Surface. Because early 2.75±0.03 Ma and the second is 2.78±0.06 Pleistocene terraces of the Rio Grande pass Ma (Maldonado et al., 1999). Basaltic west of Isleta volcano at high levels, the cinders correlated to the Isleta volcano flows volcanic edifice probably was exhumed are recognized in the Arroyo Ojito Fm during middle and late Pleistocene time exposed along the eastern margin of the Rio (Love et al., 2001). 0.1 Grande valley. These cinder-bearing 5.3 Entering cut exposing basalt flow of Isleta deposits are about 70 m (estimated) volcano over base-surge unit (see cross stratigraphically below exposures of lower section, Day 2). Shell Isleta #2 well is about Pleistocene, Lower-Bandelier-Tuff bearing 1 mi. to the west, where it reached a depth of sand and gravel of the ancestral Rio Grande 6482 m and ended in Eocene rocks. facies of the Sierra Ladrones Fm. This Lozinsky (1994) reports that the Santa Fe stratigraphic relationship indicates that Group is 4407 m thick at the Isleta #2 well deposition of the Arroyo Ojito Fm continued and is underlain by 1787 m of the Eocene- after 2.72-2.78 Ma, thereby constraining the Oligocene unit of Isleta #2, which overlies age of the mesa capping Llano de more than 288 m of sediments correlated Albuquerque to between 2.7 and 1.25 Ma. with the Eocene Baca or Galisteo fms. 1.8 Based on local stratigraphy on both sides of the present valley, it is likely that the Llano

3-2 NMBGMR OFR454C ELEVATIONS OF GEOLOGIC FEATURES, SAN CLEMENTE TO LOWER HELL CANYON, BETWEEN I-25 MILE POSTS 205 AND 206 Elevations are in feet above mean sea level as measured from USGS 7.5-minute topographic maps Arrows point to described features and elevations to your left (east) and right (west) in decreasing order of elevation. EAST WEST

base of 100,000-year-old basalt flow 1 of Cat Mesa resting on top of San Clemente graben fill 5315 Æ Å 5310 top of eastern piedmont aggradation, footwall of western Hubbell Spring fault Upper Bandelier pumice in cross-bedded sand, San Clemente graben 5300 Æ Å 5280 Lower Bandelier pumice in ancestral Rio Grande unit, footwall of western Hubbell Spring fault encroaching piedmont from Los Lunas volcano on graben-fill (1.1 km south) 5280 Æ Los Lunas volcano tephra (1.25 Ma) at top of San Clemente section (2.2 km SE) 5260 Æ Å 5260 top of ancestral Rio Grande deposits bearing Upper Bandelier boulders, north side of Hell Canyon Blancan fossil camel bones in section tilted 6 degrees SW, east of San Clemente graben 5240 Æ thick soil at base of San Clemente graben section 5220 Æ pumice in tilted section, east of San Clemente graben 5215 Æ Å 5140 top of Rio Grande gravel east of Palace-Pipeline fault, south of Hell Canyon Å 5100 top of Rio Grande gravel west of Palace-Pipeline fault Å 5065 top of Hell Canyon gravel and soil, mouth of Hell Canyon Å 5060 top of Rio Grande gravel in section at mouth of Hell Canyon Å 5000 Cerro Toledo (c.a. 1.5 Ma) ash in Janet Slate section , mouth of Hell Canyon top of Los Duranes Fm 4985 Æ

Å4915 base of exposures of ancestral Rio Grande with Lower Bandelier pumice and ash Å 4865 Rio Grande floodplain Æ Å 4863 Rio Grande floodway channel Æ

7.1 Exit 209 overpass to Isleta Pueblo. Road Los Duranes Fm at 3:00. This flow is the now on upper constructional surface of the oldest of the Cat Hills seven flows and Los Duranes Fm, a middle to upper(?) yielded two 40Ar/39Ar dates of 98±20 ka and Pleistocene inset fluvial deposit of the 110±30 ka (Maldonado et al., 1999). The ancestral Rio Grande named by Lambert Albuquerque volcanoes (dated using (1968) for exposures in NW Albuquerque. 238U/230Th method at 156±29 ka, Peate et al., The Los Duranes Fm is inset against middle 1996) overlie the Lomatas Negras fm and Pleistocene fluvial deposits correlated to the locally interfinger with the top of the Los Lomatas Negras fm, which contains an ash Duranes Fm in NW Albuquerque. These that was geochemically correlated to the dates constrain the upper limit of deposition 0.60-0.66 Ma Lava Creek B ash, from the of this extensive terrace deposit to between Yellowstone area in Wyoming (N. Dunbar, 98-156 ka, which spans the boundary of 2000, written commun,; A. Sarna-Wojcicki, marine oxygen isotope stages 5 and 6 2001, written commun.). At 3:00 is a low (Morrison, 1991). These dates and dark hill of the 4.01±0.16 Ma Wind Mesa stratigraphic constraints indicate that much volcano (Maldonado et al., 1999). The late of the deposition of the Los Duranes Fm Pleistocene Cat Hill volcanoes between occurred prior to the interglacial of marine 2:00-3:00. Hell Canyon Wash is at 9:00 on oxygen isotope stage 5. 1.0 the eastern margin of the Rio Grande Valley. 11.0 Milepost 206. Descend possible fault scarp 1.1 in Los Duranes Fm. Beneath rim of Cat 8.2 Railroad overpass. A soil described in Hills lava flows about 6 km (4 mi.) west of exposures of the uppermost Los Duranes Fm here is the San Clemente graben. It extends indicate that soils are weakly developed with northward from near Los Lunas volcano to a Stage I and II+ pedogenic carbonate graben that splits Wind Mesa (Maldonado et morphology (S.D. Connell, and D.W. Love, al., 1999). The Arroyo Ojito beds and thick unpubl. data). 0.8 stage III soil beneath the graben-fill near 9.0 Milepost 208. Between 1:00-2:00 is the rift- San Clemente are deformed into a flat- bounding uplift of Mesa Lucero, which is floored syncline. At least 37 m of fine sand, about 30 km west of here. 0.6 silt, and clay with a few coarser pebbly sand 9.6 Valencia County Line. 0.4 units accumulated in this graben where we 10.0 Milepost 207. Late Pleistocene basalt flow found a bed of fluvially recycled pumice of the Cat Hills volcanic field overlies the pebbles about 29 m above the base of the

3-3 NMBGMR OFR454C graben-fill section. These pumice pebbles produced at least three lava flows that have been geochemically correlated to the descended eastward toward the valley. V. Bandelier Tuff and have been dated Grauch (personal commun., 1999) suggests 1.21±0.03 Ma. Farther south near NM-6, that the magnetic polarity of these flows is tephra from Los Lunas volcano (ca. 1.25 reversed, indicating that they predate the Ma) overlies correlative graben-fill Brunhes chron (older than 780 ka). sediments, which lie only a few meters McIntosh (unpubl.) obtained ages of above a stage III soil that is interpreted to 1.25±0.1 Ma on some of these upper flows, mark a break in deposition of the Arroyo indicating that the eruptions and concurrent Ojito Fm along the easternmost edge of the deformation took place in less than twenty Llano de Albuquerque. 1.1 thousand years.. 0.5 12.1 Southern boundary of Isleta Reservation. El 14.2 Pass Los Morros Road to business park to Cerro de Los Lunas between 1:00-2:00. your right. 0.2 Northwest of the volcano, northwest-tilted 14.4 Pass Sand Sage Road and ascend alluvial beds of the Arroyo Ojito Fm contain apron prograded over the Los Duranes Fm. multiple layers of pumice pebbles. A pumice Relict landslide on north side of “LL” pebble collected in the middle of the section edifice at 9:30. 0.6 of the Arroyo Ojito Fm here has been 15.0 Exposures of northwest-tilted Arroyo Ojito geochemically correlated to a pumice unit deposits below skyline to the southwest of which was 40Ar/39Ar dated at 3.12±0.10 Ma NM 6. Tilting of the section is due to in the Arroyo Ojito Fm exposed beneath the deformation during emplacement of two Llano de Albuquerque in the valley of the batches of magma. An older, more tilted Rio Puerco on the Dalies NW quadrangle succession is not visible from the highway, (Maldonado et al, 1999). This pumice has but will be visited during a hike from Stop been geochemically correlated to a pumice 3-1. 0.9 pebble at Day 1, Stop 7 in Rio Rancho. 0.7 15.9 V-shaped gray syncline developed in Los 12.8 Borrow pit to right exposes weakly Lunas tephra in slopes up drainage to developed soil in Los Duranes Fm. 0.6 southwest. 1.1 13.4 Take Exit 203 to Los Lunas and NM 17.0 Hill to right is eolian falling dune covering highway 6 to west. 0.3 reworked piedmont of Los Lunas volcano. 13.7 Turn right (west) on NM 6. This road was 0.1 an early alignment of Route 66. El Cerro de 17.1 Los Lunas tephra exposed in road cuts at eye Los Lunas at 10:00 consists of several level. 0.3 eruptive centers of trachyandesite to dacite. 17.4 Contact between Los Lunas tephra and San The earliest eruption consisted of andesitic Clemente graben fill near elevation of gate and dacitic vent breccias and lava flows that to your right (north). 0.1 have an 40Ar/39Ar age of 3.81±0.1 Ma 17.5 Piedmont alluvium from Los Lunas volcano (McIntosh, unpubl; Panter et al., 1999). The exposed in road cuts. Stage III calcium north edifice with the “LL” on it is a carbonate soil horizon near top. 0.3 trachyandesite with an 40Ar/39Ar age of 17.8 Turn left (south) on “AT and T” Road. 0.6 1.25±0.1 Ma (McIntosh, unpubl; Panter et 18.4 Turn left just past power pole and before al., 1999). A separate, undated vent at the houses. Water table for this housing top of the mountain produced red and gray development at a depth of more than 900 scoraceous tephra that extended over several feet. Head east on two-track dirt road. 0.3 km2 to the north, east, and southeast of the 18.7 Pass “No Trespassing” Sign on Huning volcano. The underlying flow and scoria Ranch and head southeast. Permission must were then cut by several north-south faults. be obtained from the Huning Land Trust in The scoria vent, underlying flow, and Santa Los Lunas prior to entering ranch lands. 0.1 Fe Group strata were tilted and uplifted 18.8 Turn left on two-track road to east and more than 150 m above the surrounding prepare to leave vehicle. 0.1 landscape and rapidly eroded, forming a 18.9 Separate vehicles to be left here from four- piedmont apron to the west and northwest. wheel drive, high clearance vehicles that An eroded fault scarp on the east side of the will continue after Stop 3-1. Park on left peak has dip-separation of 56 m on the base side of road near edge of badlands. GPS, N: of the lowest 1.25 Ma flow. The next set of 3,854,000 m; E: 333,819 m, Z013S, NAD83, eruptions issued along the fault scarp and Dalies 7.5’ quadrangle. buried talus from the scarp. Between Discussion at Stop 3-1 will address seven items eruptions, minor amounts of talus and eolian of interest: (1) where are we? (2) who has done work sand buried the lava flows. The final vent here? (3) what about those volcanoes? (4) what

3-4 NMBGMR OFR454C relation does the basin fill have to the volcanoes? (5) Maldonado et al draft map; Aeromagnetic maps; what’s happened since the last eruption in the way of gravity map; tops of basin fill—Llanos: Albuquerque, erosion of the volcano and consequent piedmont Sunport, Manzano, San Clemente, Los Lunas volcano deposition? (6) what’s the history of post-piedmont piedmont. Basin fill thickness—Shell Isleta # 2: erosion on the north, south, and southwest flanks of 6,482 m deep; Santa Fe Group 4,407 m or 4,941m the piedmont? And most importantly, (7) where do Shell Isleta # 1: 2,679 m of Santa Fe we go from here, what do we see, how long will it Group/Cretaceous at 3,670 m TransOcean 1,536 m of take, and what should participants take with them? Santa Fe Group (TD in Precambrian at 3,163 m) Long-Dalies 2,589 m of Santa Fe Group; Harlan 864 1) Where are we? m of Santa Fe Group. Sources of basin fill—west, Regional setting of Los Lunas volcano: Topics north, northeast (Rio Grande), east (piedmont of and visual aids to cover--position near center of Manzano Mountains not found here). Where was the Albuquerque basin, visual landmarks around basin Rio Grande? Post-Santa Fe development of Rio and margins of basin; Mid-basin rift setting— Grande valley in inset steps.

Figure 3-1. Aerial photograph of El Cerro de los Lunas and vicinity. North is to the right (U.S. Geological Survey air photo, 1990, GS-VFN, No. 2-83).

3-5 NMBGMR OFR454C

Figure 3-2. Cross section across northwestern flank of Los Lunas volcano.

Figure 3-3. Reflection seismic profile along the northwest piedmont slope of Los Lunas volcano (C. Reynolds, unpubl. data). Note dipping reflectors and unconformities at 0.2 to 0.5 seconds two-way travel time (scale on right margin 0 to 0.7 seconds).

3-6 NMBGMR OFR454C

Figure 3-4. Photograph of the white Tshirege ash overlying blocks of the 1.25 Ma Los Lunas trachyandesite.

Figure 3-5. View to north of west-tilted Arroyo Ojito Fm (local package 2).

3-7 NMBGMR OFR454C

2) Who worked here? colluvium and alluvium and stage III soils includes T. Galusha; V. Kelley and A. Kudo; J. Kasten; J. fallout of Tshirge ash (upper Bandelier--1.22 Ma) in Renault; G. Bachman & J. Mehnert; J. Hawley, R. a paleovalley cut into tilted Pliocene sediments. We Lozinsky, J. Young, D. Love; C. Reynolds; K. Panter descend into the present canyon and see part of the and B. Hallett; W. Haneberg; N. Dunbar and W. middle package that includes Pliocene pumice mixed McIntosh; C. McKee; S. L. Minchak; H. D. Southern; with western-margin facies and eolian sand. At the H. D. Rowe; J. Geissman. base of exposures in the canyon, we see a profound angular unconformity between an older (Pliocene?) 3) Los Lunas volcano(es) Elevations: Top 5955 ft pumice-bearing third package of sediments and the (1815 m), west side 5300-5700 (1615-1737 m), east tilted beds we have just examined. Then we walk side 5050 ft (1539 m), base of badlands to south 5100 northward through the tilted section to examine the ft (1554 m), Dalies to SW 5305 ft (1617 m). High Pliocene and Pleistocene beds where it is more easily edifices—NE 1.25 Ma, central 1.25, SE scoria on NE accessible. We look at deformation of sediments by flow 1.25 Ma; Low, tilted edifice to SW—3.8 Ma; faults and folds. To the north we find the 1.25 Ma also outliers to south that we can’t see from here (Fig. tephra from the second eruption of Los Lunas 3-1)Large north-trending fault offsets first flow (59 m volcano deformed in a syncline and anticline in the of displacement, down to east; other, smaller faults to section, immediately overlain by sediments reworked east and west. Chemistry of flows—early (3.8) from the uplifted volcano. andesite & dacite, late (1.25) trachyandesite. We will examine unusual reverse faults, cuspate and lobate structures, and low-angle thrust faults 4) Relation of volcanoes to basin fill: Pre-3.8 Ma involving plates of unconsolidated sediments only a sediments (> 40 m exposed)—western-source pebbly few m thick (who would have thought that sands and eolian; deformation by folds and faults unconsolidated sediments would be considered (normal and thrusts). Flow-front deformation of “competent” [see article by Haneberg, this volume]). sediments and tephra (normal & thrusts). Post 3.8 Ma Farther north, we see the Los Lunas tephra flatten out tilting, faulting, burial first with eolian (20-40 m), on top of fine-grained sediments in the San Clemente then 150 m of fluvial and eolian section below 1.25 graben. Above the tephra, we walk through 50 m of Ma tephra. alluvial sediments derived from the uplifted youngest Problem with southern “intrusives”—outcrops eruption of Los Lunas volcano and Arroyo Ojito look intrusive, but they are buried by sediments sediments on our way back to the vehicles at the containing adjacent eroded igneous blocks—so what lower parking lot. were these igneous bodies intruding? We hope to complete this traverse within 4 1.25 Ma eruptions and deformation: first, hours. The climb down is steep, and there is a small “chocolate brown” (CB) flow and edifice; second chance of finding rattlesnakes among boulders at the “red and gray” scoria cone and tephra; deformation bottom. The climb out is not particularly steep, but of tephra—folds, reverse faults, low-angle thrusts, may require extra effort. Take water, food, sunscreen, normal faults, cuspate-lobate structures; normal faults and walking tools. with ~59 m of displacement; uplift beneath volcano Selected vehicles will drive south (uphill) to of 155 m above rest of Llano de Albuquerque; talus; upper parking area. Roadlog from lower parking area third edifice and late flows cover faults to upper parking area.

5) Post-tephra erosion and piedmont deposition Reset odometer. (~50 m of fill) Relation to San Clemente graben; 0.0 Return to larger dirt two-track and turn local seismic profiles. southeast (left) toward volcano. 0.1 Where is “Llano de Albuquerque” (top of basin 0.1 Route towards volcano is along the top of fill) in this section? undissected piedmont slope covered with Holocene eolian sand dunes. 0.1 6) Post-piedmont erosion and deposition of 0.2 View of highest part of Los Lunas volcano intermediate landscape levels and current deep at 12:00. This consists of a red scoria cone canyons overlying a trachyandesite flow. The volcanic units make up only the upper 40-45 7) Where are we going from here? What will we m of the mountain. Underlying the flow is see? How long will it take? local package 2 of Arroyo Ojito Fm mostly We shuttle the group with as few high-clearance exposed. Package one of Arroyo Ojito Fm is vehicles as possible up slope to edge of steep canyon exposed in deep arroyos north and south of between us and the volcano. We look at three this summit. To the east at 11:30 is the fault packages of sediments between angular with ~56 m of offset judging from the base unconformities. The upper package of local of the trachyandesite flow on either side of

3-8 NMBGMR OFR454C the fault. Farther to the east is the “LL” 0.8 Turn left (east) on two track road. 0.2 edifice at 10:30 and numerous landslides 1.0 Turn around where possible and park out from 10:30 to 10:00. 0.5 of roadway. Prepare to hike downslope. 0.7 Low black outcrops to southwest (1:00) are GPS, N: 3,852,855 m; E: 334,640 m, Z013S, nearly buried tops of 3.81 Ma tilted lava NAD83, Dalies 7.5’ quadrangle. flows. 0.1

Outline of landscape development around Los Lunas volcano

D. Love, B. Hallett, K. Panter, N. Dunbar, W. McIntosh, J. Hawley, R. Lozinsky, J. Young, C. Reynolds, S. Connell, W. Haneberg

Los Lunas volcano consists of two sets of thrust faults to northwest of edifice and edifices—an older tilted one (and outliers) to the subsequently buried by erosional debris from southwest at 3.81 ± 0.10 Ma, and a younger one to southeast the northeast at 1.25 ± 0.02 Ma. The local landscape 5) N-S faults also cut “chocolate brown” edifice to consists of the two sets of volcanic edifices, east; probably NE faults west of cinder edifice subvolcanic basin fill, piedmont apron around 6) talus develops on free face of major N-S fault western side, river-cut valley and terrace to east, and 7) new edifice erupts along fault and produces flow erosional drainage basins to NW, S and SW. 3 down east side Present drainages show influence of differential 8) eolian sand partially covers flow 3 on east side erosion of basin-fill, structure (faulting and folding), 9) flows 4 descend down east side from edifice on resistance of lava flows; colluvial processes fault, forming symmetrical flow lobes clearly (landslides, slumps, rock falls); and oriented eolian visible in photographs processes. After eruptions ceased Events • East side—very linear—either fault or Rio • Pre-volcanic basin fill from west and north— Grande truncation prior to Los Duranes typical western margin facies (Arroyo Ojito Fm), sedimentation but deformed and exposed here; • NW side—after eruptions and faulting, paleo- • Deformation precedes first eruptions; faulting valley eroded in uplifted Santa Fe Group and dramatic tilting of Santa Fe Group beds; sediments, blocks of CB and cinders into the • 3.81 Ma andesite and dacite eruptions: paleovalley, 1.22 Ma Tshirge ash of Bandelier • tephra overridden by andesite flows with into the valley. Up to 50 m of accumulation in concurrent deformation. Flows are tilted. the valley; extension of alluvial apron to • Eolian aggradation around and over the top of northwest, west, and southwest; apron may the flows before fluvial western-margin gravels interfinger with San Clemente graben fill; large come back into picture. Then pumice and eolian component to apron from SW. obsidian arrive with western-margin fluvial • South side—early drainages off SW side of clasts. 150 m of section accumulates; uplifted volcano, development of drainages • Stage III soil forms at least in some areas; down south side and across SE flows of volcano; • San Clemente graben forms—primarily to north transport of recycled Arroyo Ojito clasts from and northwest. Soil develops on margins of southwest side onto SE flow lobes, entrenchment graben, sediments accumulate in graben. of upper flow. Then south-side drainage gets captured to flow west and south. Eolian 1.25 Ma eruptions of El Cerro de los Lunas influence of meander courses; migrates down south-tilted dip slope. 1) NE edifice with “chocolate brown” (CB) flow • Creation of renewed erosional relief both north across landscape—on edge of San Clemente side and south side. graben (some exposures have stage III soil, • Recycling of western alluvial apron into others just alluvium beneath first flow). Flow in intermediate alluvial apron on north side and SW area ponds into “lava lake” > 30 m thick. south side of Los Lunas volcano 2) cinder and red scoria edifice erupts to WSW of • Creation of renewed erosional relief on both first edifice north side and south side. 3) cinder edifice is uplifted and offset 56 m along • Recycling of western alluvial apron and N-S fault, forms top of “El Cerro de Los Lunas” intermediate alluvial apron into an even lower 4) cinders with blocks of first flow are folded into alluvial apron on north side and south side of syncline, anticline, and faulted with reverse and Los Lunas volcano. 3-9 NMBGMR OFR454C • Routing of hairpin turn in drainage on south Bryan, K., McCann, F.T., 1936, Successive pediments and side—eolian influence here too. Transport from terraces of the upper Rio Puerco in New Mexico: head of SW badlands across old edifice and Journal of Geology, 44, n. 2, p. 145-172 eastward. Definite eolian influence on west side Bull, W.B., 1984, Tectonic geomorphology: Journal of Geologic Education, v. 32, p. 310-324. of SE flow lobes— eolian ramp across top and Bull, W.B., 1991, Geomorphic responses to climate into ENE area on top of (and between) flows. changes: New York, Oxford University Press, 326 p. • Southwest drainage hangs up on older lava Cather, S.M., and Connell, S.D., 1998, Geology of the San flows, incises meanders with two mouths to Felipe Pueblo 7.5-minute quadrangle, Sandoval drainage across lava, depending on NE trending County, New Mexico: New Mexico Bureau of Mines faults; Far SW drainage through NE trending and Mineral Resources, Open-File Digital Map 19, grabens; curved drainages along strike around scale 1:24,000. uplift of older Tsf—both far southwest side and Cather, S.M., and McIntosh, W.C., 1990, Volcanogenic flood deposits near San Antonio, New Mexico- north side of Los Lunas volcano. depositional processes and implications: Sediments • th Southwest drainage establishes new, lower route 1990, 13 International Sedimentological Congress, as badlands are stripped out. Nottingham, England, 80 p. • Landslides, slumps, Toreva blocks continue to Cather, S.M., Connell, S.D., and Black, B.A., 2000, develop on steep slopes. Preliminary geologic map of the San Felipe Pueblo • Eolian dunes, distended parabolic arms, rim NE 7.5-minute quadrangle, Sandoval County, New dunes on NE side of SW badlands and on parts Mexico: New Mexico Bureau of Mines and Mineral Resources, Open-file Digital Map DM-37, scale of the volcanoes on landscape now. 1:24,000. Cather, S.M., Connell, S.D., and Black, B.A., 2000, ROAD LOG REFERENCES Preliminary geologic map of the San Felipe Pueblo (probably incomplete) NE 7.5-Minute quadrangle, Sandoval County, New Mexico: New Mexico Bureau of Mines and Mineral Resources, Open-File Geologic Map OF-GM 37, scale Abbott, J.C., and Goodwin, L.B., 1995, A spectacular 1:24,000. exposure of the Tijeras fault with evidence for Cole, J.C., Stone, B.D., Shroba, R., and Dethier, D., 2001a, Quaternary motion: New Mexico Geological Society Episodic Pliocene and Pleistocene drainage integration Guidebook 46, p. 117-125. along the Rio Grande through New Mexico [abstract]: Allen, B.D., and Anderson, R.Y., 2000, A continuous, Geological Society of America, Abstracts with high-resolution record of late Pleistocene climate Programs, v. 33, n.7. variability from the Estancia Basin, New Mexico: Cole, J.C., Stone, B.D., Shroba, R., and Dethier, D., 2001b, Geological Society of America Bulletin, v. 112, n. 9, Pliocene incision of the Rio Grande in northern New p. 1444-1458. Mexico [abstract]: Geological Society of America, Ayarbe, J. P., 2000, Coupling a fault-scarp diffusion model Abstracts with Programs, v. 33, n.5, p. A-48. with cosmogenic 36Cl rupture chronology of the Connell, S.D., 1997, Geology of the Alameda 7.5-minute Socorro Canyon fault, New Mexico [M.S. thesis]: quadrangle, Bernalillo and Sandoval Counties, New Socorro, New Mexico Institute of Mining and Mexico: New Mexico Bureau of Mines and Mineral Technology, Socorro, 71 p. Resources, Open-File Digital Map 10, scale 1:24,000. Bachman, G. O., and Mehnert, H.H., 1978, New K-Ar Connell, S.D., 1998, Geology of the Bernalillo 7.5-minute dates and the late Pliocene to Holocene geomorphic quadrangle, Sandoval County, New Mexico: New history of the central Rio Grande region, New Mexico: Mexico Bureau of Mines and Mineral Resources, Geological Society of America, Bulletin, v. 89, p. 283- Open-File Digital Map 16, scale 1:24,000. 392. Connell, S.D., and Wells, S.G., 1999, Pliocene and Black, B.A., and Hiss, W.L., 1974, Structure and Quaternary stratigraphy, soils, and geomorphology of stratigraphy in the vicinity of the Shell Oil Co. Santa the northern flank of the Sandia Mountains, Fe Pacific No. 1 test well, southern Sandoval County, Albuquerque Basin, Rio Grande rift, New Mexico: New Mexico: New Mexico Geological Society, New Mexico Geological Society, Guidebook 50, p. Guidebook 25, p. 365-370. 379-391. Blair, T., Bilodeau, W.L., 1988, Development of tectonic Connell, S.D., and Love, D.W., 2000, Stratigraphy of Rio cyclothems in rift, pull-apart, and foreland basins; Grande terrace deposits between San Felipe Pueblo sedimentary response to episodic tectonism, v. 16, n. and Los Lunas, Albuquerque Basin, New Mexico 6. [abstract]: New Mexico Geology, v. 22, n. 2, p. 49. Bryan, K and McCann, F. T., 1937, The Ceja del Rio Connell, S.D. Cather, S.M., Karlstrom, K.E., Read, A., Ilg, Puerco, a border feature of the Basin and Range B., Menne, B., Picha, M.G., Andronicus, C., Bauer, province in New Mexico: Journal of Geology, v. 45, p. P.W., and Anderson, O.J., 1995, Geology of the 801-828. Placitas 7.5-minute quadrangle, Sandoval County, Bryan, K., and McCann, F.T., 1938, The Ceja del Rio New Mexico: New Mexico Bureau of Mines and Puerco-a border feature of the Basin and Range Mineral Resources, Open-File Digital Map 2, scale province in New Mexico, part II, geomorphology: 1:12,000. Journal of Geology, v. 45, p. 1-16. Connell, S.D., Allen, B.D., and Hawley, J.W., 1998a, Subsurface stratigraphy of the Santa Fe Group from

3-10 NMBGMR OFR454C borehole geophysical logs, Albuquerque area, New Gawthorpe, R.L., Leeder, M.R., 2000, Tectono- Mexico: New Mexico Geology, v. 20, n. 1, p. 2-7. sedimentary evolution of active extensional basins: Connell, S.D., Allen, B.D., Hawley, J.W., and Shroba, R., Basin Research, v. 12, n. 3-4, p. 195-218. 1998b, Geology of the Albuquerque West 7.5-minute Gerson, R., 1982, Talus relicts in deserts: a key to major quadrangle, Bernalillo County, New Mexico: New climatic fluctuations: Israel Journal of Earth Sciences, Mexico Bureau of Mines and Mineral Resources, v. 31, n.2-4, p. 123-132. Open-File Digital Geologic Map 17, scale 1:24,000. Gile, L.H., Hawley, J.W., and Grossman, R.B., 1981, Soils Connell, S.D., Koning, D.J., and Cather, S.M., 1999, and geomorphology in the Basin and Range area of Revisions to the stratigraphic nomenclature of the southern New Mexico-Guidebook to the Desert Santa Fe Group, northwestern Albuquerque basin, Project: New Mexico Bureau of Mines and Mineral New Mexico: New Mexico Geological Society, Resources, Memoir 39, 222 p. Guidebook 50, p. 337-353. Gile L. H., Hawley, J. W., Grossman, R. G., Monger, H. C., Connell, S.D., Love, D.W., Maldonado, F., Jackson, P.B., Montoya, C. E., and Mack, G. H., 1995, Supplement McIntosh, W.C., and Eppes, M.C., 2000, Is the top of to the Desert Project Guidebook, with emphasis on the Santa Group diachronous in the Albuquerque soil micromorphology: New Mexico Bureau of Mines Basin? [abstract]: U.S. Geological Survey, Open-file and Mineral Resources Bulletin 142, 96 p. report 00-488, p. 18-20. Grauch, V. J. S., 1999, Principal features of high-resolution Connell, S.D., Koning, D.J., and Derrick, N.N., 2001, aeromagnetic data collected near Albuquerque, New Preliminary interpretation of Cenozoic strata in the Mexico: New Mexico Geological Society, Guidebook Tamara No. 1-Y well, Sandoval County, north-central 50, p. 115-118. New Mexico: New Mexico Bureau of Mines and Grauch, V.J.S., 2001, High-resolution aeromagnetic data, a Mineral Resources, Open-file report 454B, p. K-79-K- new tool for mapping intrabasinal faults: Example 88. from the Albuquerque basin, New Mexico: Geology, Connell, S.D., Love, D.W., Cather, S.M., Smith, G.A., and v. 29, no. 4 p. 367-370. Lucas, S.G., 2001b, Tectonics, climate, and the Grauch, V.J.S., Gillespie, C.L., and Keller, G.R., 1999, transition from aggradation to incision of the upper Discussion of new gravity maps for the Albuquerque Santa Fe Group, Albuquerque Basin, central New Basin area: New Mexico Geological Society, Mexico [abstract]: Geological Society of America, Guidebook 50, p. 119-124. Abstracts with Programs, v. 33, n.5, p. A-48. Hallett, R.B., Kyle, P.R., and McIntosh, W.C., 1997, Connell, S.D., Love, D.W., Jackson-Paul, P.B., Lucas, Paleomagnetic and 40Ar/39Ar age constraints on the S.G., Morgan, G.S., Chamberlin, R.M., McIntosh, chronologic evolution of the Rio Puerco volcanic W.C., Dunbar, N., 2001a, Stratigraphy of the Sierra necks and Mesa Prieta, west-central New Mexico: Ladrones Formation type area, southern Albuquerque Implications for transition zone magmatism: Basin, Socorro County, New Mexico: Preliminary Geological Society of America Bulletin, v. 109, no. 1, Results [abstract]: New Mexico Geology, v. 23, n. 2, p. 95-106. p. 59. Haneberg, W.C., 1992, Geologic hazards in New Mexico; Connolly, J. R., 1982, Structure and metamorphism in the Part 2: New Mexico Geology, v. 14, n. 3, p. 45-52. Precambrian Cibola gneiss and Tijeras greenstone, Haneberg, W.C., 1999, Effects of valley incision on the Bernalillo county, New Mexico: New Mexico subsurface state of stress--theory and application to Geological society, 33rd Field Conference, p. 197-202. the Rio Grande valley near Albuquerque, New Mexico: Environmental & Engineering Geoscience, v. Connolly J. R., Woodward, L. A., and Hawley, J. W., 1982, 5, p. 117-131. Road-Log segment I-A: Albuquerque to Tijeras Haneberg, W.C., Gomez, P., Gibson, A., and Allred, B., Canyon: New Mexico Geological Society, 33rd Field 1998, Preliminary measurements of stress-dependent Conference, p. 2-8. hydraulic conductivity of Santa Fe Group aquifer Dart, C., Cohen, H.A., Akyuz, H.S, and Barka, A., 1995, system sediments, Albuquerque Basin, New Mexico: Basinward migration of rift-border faults: implications New Mexico Geology, v. 20, p. 14-20. for facies distributions and preservation potential: Hawley, J.W., ed., 1978, Guidebook to Rio Grande rift in Geology, v. 23, n. 1, p. 69-72. New Mexico and Colorado: New Mexico Bureau of Derrick, N.N., and Connell, S.D., 2001, Petrography of Mines and Mineral Resources, Circular 163, 241 p. upper Santa Fe Group deposits in the northern Hawley, J. W., 1996, Hydrogeologic framework of Albuquerque basin, New Mexico: Preliminary Results potential recharge areas in the Albuquerque Basin, [abstract]: New Mexico Geology, v. 23, n. 2, p. 58-59. central New Mexico: New Mexico Bureau of Mines Dunbar, N., McIntosh, W.C., Cather, S.M., Chamberlin, and Mineral Resources, Open-file Report 402 D, R.M., Harrison, B., Kyle, P.R., 1996, Distal tephras Chapter 1, 68 p., appendix. from the Jemez volcanic center as time-stratigraphic Hawley, J. W., Love, D. W., and Lambert, P. W., 1982, markers in ancestral Rio Grande sediments from the Road-log segment I-C: Abo Canyon –Blue Springs Socorro area: New Mexico Geological Society, area to Albuquerque via Belen and Los Lunas: New Guidebook 47, p. 69-70. Mexico Geological Society, 33rd Field Conference, p. Ferguson, C. A., Timmons, J. M., Pazzaglia, F. J., 24-30. Karlstrom, K. E., and Bauer, P. W., 1998, Geologic Hawley, J.W. and Haase, C.S., 1992, Hydrogeologic map of the Sandia Park quadrangle, Bernalillo and framework of the northern Albuquerque Basin: New Sandoval Counties, New Mexico: New Mexico Mexico Bureau of Mines and Mineral Resources, Bureau of Mines and Mineral Resources, Open-file Open-file Report 387, 165 p. Report DM-1, 12 p. scale 1:24,000. Hawley, J.W., Haase, C.S., Lozinsky, R.P., 1995, An underground view of the Albuquerque Basin: New 3-11 NMBGMR OFR454C Mexico Water Resources Research Institute, Report Love, D. W., 1989, Geomorphic development of the Rio 290, p. 27-55. San Jose valley: New Mexico Geological Society 40th Izett, G. A., and Wilcox, R. E., 1982, Map showing Field Conference Guidebook, pp. 11-12. localities and inferred distributions of the Huckleberry Love, D. W., 1997, Geology of the Isleta 7.5-minute Ridge, Mesa Falls, and Lava Creek ash beds (Pearlette quadrangle, Bernalillo and Valencia Counties, New family ash beds) of Pliocene and Pleistocene age in Mexico: New Mexico Bureau of Mines and Mineral the western United States and southern Canada: U. S. Resources, Open-file Digital Geologic Map 13, scale Geological Survey, Miscellaneous Investigations 1:24,000. Series, Map I-1325, scale 1:4,000,000. Love, D.W. and Whitworth, T. M., 2001, Description and Izett, G. A., and Obradovich, J. D., 1994, 40Ar/39Ar age models of distinctive calcium-carbonate nodules and constraints for the Jaramillo Normal Subchron and the discontinuous cementation from shallow ground-water Matuyama-Brunhes geomagnetic boundary: Journal of seepage in hanging walls of Pleistocene faults Geophysical Research, v. 99, p. 2925-2934. [abstract]: New Mexico Geology, v. 23, no. 2, p. 60. Izett, G.A. Pierce, K.L., Naesser, N.D., and Jawarowski, C., Love, D.W., Dunbar, N., McIntosh, W.C., McKee, C., 1992, Isotopic dating of Laver Creek B tephra in Connell, S.D., Jackson-Paul, P.B., and Sorrell, J., terrace deposits along the Wind River, Wyoming: 2001, Late-Miocene to early-Pleistocene geologic Implications for the post 0.6 Ma uplift of the history of Isleta and Hubbell Spring quadrangles based Yellowstone hotspot: U.S. Geological Survey, Open- on ages and geochemical correlation volcanic rocks file report 92-391, 33 p. [abstract]: New Mexico Geology, v. 23, n. 2, p. 58. Karlstrom, K.E., Chamberlin, R.C., Connell, S.D., Brown, Lozinsky, R.P., 1988, Stratigraphy, sedimentology, and C., Nyman, M., Cavin, W., Parchman, M., Cook, C., sand petrography of the Santa Fe Group and pre-Santa Sterling, J., 1997, Geology of the Mt. Washington 7.5- Fe Tertiary deposits in the Albuquerque Basin, central minute quadrangle, Bernalillo and Valencia Counties, New Mexico [Ph.D. dissert.]: Socorro, New Mexico New Mexico, New Mexico Bureau of Mines and Institute of Mining and Technology, 298 p. Mineral Resources, Open-File Geologic Map OF-GM Lozinsky, R. P., 1994, Cenozoic stratigraphy, sandstone 8, scale 1:12,000 and 1:24,000. petrology, and depositional history of the Albuquerque Karlstrom, K.E., Cather, S.M., Kelley, S.A., Heizler, M.T., basin, central New Mexico: Geological Society of Pazzaglia, F.J., and Roy, M., 1999, Sandia Mountains America Special Paper 291, p. 73-81. and the Rio Grande rift: ancestry of structures and Lucas, S.G., Williamson, T.E., and Sobus, J., 1993, Plio- history of deformation: New Mexico Geological Pleistocene stratigraphy, paleoecology, and Society, Guidebook 50, p. 155-165. mammalian biochronology, Tijeras Arroyo, Kelley, V. C., 1977, Geology of Albuquerque Basin, New Albuquerque area, New Mexico: New Mexico Mexico: New Mexico Bureau of Mines and Mineral Geology, v. 15, n. 1, p. 1-8. Resources, Memoir 33, 60 p. Mack, G.H., 2001, Evolution of Cenozoic extensional Kelley, V.C., 1982, Albuquerque-its mountains, valley, block faulting and sedimentation in the southern Rio water, and volcanoes: New Mexico Bureau of Mines Grande rift, New Mexico [abstract]: Geological and Mineral Resources, Scenic Trips to the Geologic Society of America, Abstracts with Programs, v. 33, n. Past No. 9, 106 p. 5, p. A-47. Kelley, V.C. and Kudo, A.M., 1978, Volcanoes and related Mack, G.H. and Seager, W.R., 1990, Tectonic controls on basalts of Albuquerque basin, New Mexico: New facies distribution of the Camp Rice and Palomas Mexico Bureau of Mines and Mineral Resources Formations (Pliocene-Pleistocene) in the southern Rio Circular 156, 30 p. Grande rift: Geological Society of America Bulletin, Kelson, K. I., Hitchcock, C. S., and Harrison, J. B. J., 1999, v.102, p.45-53. Paleoseismology of the Tijeras fault near Golden, New Mack, G.H., Salyards, S.L., and James, W.C., 1993, Mexico: New Mexico Geological Society, 50th field Magnetostratigraphy of the Plio-Pleistocene Camp conference, p. 201-209. Rice and Palomas Fms in the Rio Grande rift of Kelson, K.I., Hitchcock, C.S., and Randolph, C.E., 1999, southern New Mexico: American Journal of Science, Liquefaction susceptibility in the inner Rio Grande v. 293, p. 47-77. Valley, near Albuquerque, New Mexico: Final Mack, G.H., McIntosh, W.C., Leeder, M.R., and Monger, Technical Report, U.S. Geological Survey, National H.C., 1996, Plio-Pleistocene pumice floods in the Hazards Reduction Program, Award No. 98-HQ-GR- ancestral Rio Grande, southern Rio Grande rift, New 1009, 40 p. Mexico, USA: Sedimentary Geology, v. 103, p. 1-8. Lambert, P. W., 1968, Quaternary stratigraphy of the Machette, M. N., 1978, Geologic map of the San Acacia Albuquerque area, New Mexico [Ph.D. dissert.]: quadrangle, Socorro County, New Mexico: U. S. Albuquerque, University of New Mexico, 329 p. Geological Survey, Geologic quadrangle Map GQ Leeder, M. R., and Jackson, J. A., 1993, The interaction 1415, scale 1:24,000. between normal faulting and drainage in active Machette, M.N., 1985, Calcic soils of the southwestern extensional basins, with examples from the western United States: Geological Society of America Special United States and central Greece: Basin Research, v. Paper 203, p. 1-21. 5, no. 2, p. 79-102. Machette, M.N., Personius, S.F., Kelson, K.I., Haller, Love, D. W., 1986, A geological perspective of sediment K.M., and Dart, R.L., 1998, Map and data for storage and delivery along the Rio Puerco, central Quaternary faults and folds in New Mexico: U.S. New Mexico, in Hadley, R. F. (ed.), Drainage basin Geological Survey Open-File Report 98-821, 443 p., 1 sediment delivery: International Association of pl. Hydrological Sciences, Publication 159, pp. 305-322. Machette, M.N., Long, T., Bachman, G.O., and Timbel, N.R., 1997, Laboratory data for calcic soils in central 3-12 NMBGMR OFR454C New Mexico: Background information for mapping Schumm, S.A., 1965, Quaternary paleohydrology, in Quaternary deposits Wright, H.E., and Frey, D.G., eds, The Quaternary of Maldonado, F., and Atencio, A., 1998a, Preliminary the United States: New Jersey, Princeton University geologic map of the Wind Mesa quadrangle, Press, p. 783-794. Bernalillo County, New Mexico: U.S. Geological Sargeant, K., 1987, Coping with the river: Settlements in Survey, Open-file Report 97-740, scale 1:24,000. Albuquerque’s north valley, in Poor, A.V., and Maldonado and Atencio, 1998b Preliminary geologic map Montgomery, J., eds., Papers of the Archaeological of the Dalies NW quadrangle, Bernalillo County, New Society of New Mexico: Santa Fe, New Mexico, Mexico: U.S. Geological Survey, Open-file Report 97- Ancient City Press, p. 31-47. 741, scale 1:24,000. Smith, G.A., 1994, Climatic influences on continental Maldonado, F., Connell, S.D., Love, D.W., Grauch, V.J.S., deposition during late-stage filling of an extensional Slate, J.L., McIntosh, W.C., Jackson, P.B., and Byers, basin, southeastern Arizona: Geological Society of F.M., Jr., 1999, Neogene geology of the Isleta America Bulletin, v. 106, n. 9, p. 1212-1228. Reservation and vicinity, Albuquerque Basin, New Smith, G.A., Kuhle, A.J., McIntosh, W.C., 2001, Mexico: New Mexico Geological Society Guidebook Sedimentologic and geomorphic evidence for seesaw 50, p. 175-188. subsidence of the Santo Domingo accommodation- McCalpin, J. P., 1997, Paleoseismicity of Quaternary faults zone basin, Rio Grande Rift, New Mexico: Geological near Albuquerque, New Mexico: unpublished Final Society of America Bulletin, v. 113, n. 5, p. 561-574 Technical Report submitted to U.S. Geological Survey Stix, J., Goff, F., Gorton, M., Heiken, G., and Garcia, S.R., by GEO-HAZ Consulting, Inc., Contract 1434-HQ-96- 1988, Restoration of compositional zonation in the GR-02751, October 6, 1997, 18 p. Bandelier silicic magma chamber between two Morrison, R.B., 1991, Introduction, in Morrison, R.B., ed., caldera-forming eruptions: geochemistry and origin of Quaternary nonglacial geology: conterminous U.S.: the Cerro Toledo Rhyolite, Jemez Mountains, New Geological Society of America, The Geology of North Mexico: Journal of Geophysical Research, v. 93, B6, America, v. K-2, p. 1-12. p.6129-6147. Mozley, P.S. and Davis, J.M., 1996. Relationship between Stearns, C. E., 1953, Tertiary geology of the Galisteo- oriented calcite concretions and permeability Tonque area, New Mexico: Geological Society of correlation in an alluvial aquifer, Sierra Ladrones America Bulletin, v. 64, p. 459-508. Formation, New Mexico: Journal of Sedimentary Stone, B.D., Cole, J.C., Shroba, R., 2001a, Control of inset Research, v. 66, p. 11-16. alluvial terrace deposits in the Rio Grande drainage, Panter, K., Hallett, B., Love, D., McKee, C., and north central New Mexico [abstract]: Geological Thompson, R., 1999, A volcano revisited: A Society of America, Abstracts with Programs, v. 33, preliminary report of the geology of Los Lunas n.7. Volcano, central New Mexico [abstract]: New Mexico Stone, B.D., Cole, J.C., Shroba, R., 2001b, Quaternary Geology, v. 21, p. 44. climate-cycle control of inset alluvial terrace deposits Peate, D. W., Chen, J. H., Wasserburg, G. J., and in the Rio Grande drainage, northern New Mexico Papanastassiou, D. A., 1996, 238U-230Th dating of a [abstract]: Geological Society of America, Abstracts geomagnetic excursion in Quaternary basalts of the with Programs, v. 33, n. 5, p. A-49. Albuquerque volcanoes field, New Mexico (USA): Tedford, R.H., and Barghoorn, S., 1999, Santa Fe Group Geophysical Research Letters, v. 23, n. 17, p. 2271- (Neogene), Ceja del Rio Puerco, northwestern 2274. Albuquerque Basin, Sandoval County, New Mexico: Personius, S.F., 1999, Paleoearthquake recurrence in the New Mexico Geological Society, Guidebook 50, p. Rio Grande rift new Albuquerque, New Mexico 327-335. [abstract], in Schwartz, D., and Satake, K. (eds.), Thomas, E., Van Hart, D., McKitrick, S., Gillentine, J., Proceedings of the Paleoseismology Workshop, March Hitchcock, C., Kelson, K., Noler, J., and Sawyer, T., 15, 1999, Tsukuba, Japan: U.S. Geological Survey, 1995, Conceptual geologic model of the Sandia Open-file report 99-400, p. 26- 32. National Laboratories and Kirtland Airforce Base: Personius, S.F., Eppes, M.C., Mahan, S.A., Love, D.W., Technical Report, Site-Wide Hydrogeologic Mitchell, D.K., and Murphy A., 2001, Log and data Characterization Project, Organization 7584, from a trench across the Hubbell Spring fault zone, Environmental Restoration Program. Prepared by Bernalillo County, New Mexico: U.S. Geological GRAM, Inc., Albuquerque, New Mexico; and William Survey, Miscellaneous Field Studies Map MF-2348, Lettis and Associates, Oakland, California, various version 1.1. pagination. Reneau, S. L., and Dethier, D. P, 1996, Pliocene and Tonkin, P. J., Harrison, J. B. J., Whitehouse, I. E., and Quaternary history of the Rio Grande, White Rock Campbell, A. S., 1981, Methods for assessing late Canyon and vicinity, New Mexico: New Mexico Pleistocene and Holocene erosion history in glaciated Geological society Guidebook, 47th Field Conference, mountain drainage basins, in, Davies, T. R. H.; and p. 317-324. Pearce, Andrew J., eds., Erosion and sediment Ruhe, 1967, Geomorphic surfaces and surficial deposits in transport in Pacific Rim steeplands, IAHS-AISH southern New Mexico: New Mexico Bureau of Mines Publication No. 132, p. 527-543. and Mineral Resources, Memoir 18, 65 p. Russell, L.R., and Snelson, S., 1994, Structure and tectonic of the Albuquerque basin segment of the Rio Grande rift: Insights from reflection seismic data: Geological Society of America Special Paper 291, p. 83-112.

3-13 NMBGMR OFR454D Terraces of Hell Canyon and its tributaries, Memorial Draw and Ojo de la Cabra

DAVID W. LOVE New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, Socorro, NM 87801-4796

INTRODUCTION Hell Canyon and its subsidiary drainage basins currently encompass about 300 km2 and are According to Jackson (1997, p. 657) a terrace is elongate east-west. Hell Canyon drainage arises in only a geomorphic form, a “valley-contained, the Manzano and Manzanita Mountains at elevations aggradational form composed of unconsolidated up to 2,880 m and debouches to the Rio Grande material” at elevations separated from the present floodplain just below 1,500 m. More than half of the drainage system—above channel, floodplain, and drainage is above 1,880 m (6000 ft, roughly lower graded valley borders. Terraces consist of both steep tree line). The terraces of Hell Canyon are almost risers and flat treads. Leopold et al. (1964) argue that exclusively below 1,880 m. The two tributaries deposits beneath the form should not be called preserving multiple terraces, Ojo de la Cabra and terraces, but alluvial fill or alluvium or alluvial Memorial Draw (a northern tributary of Hell Canyon, deposits. In contrast, Bull (1991) coined terms named here for a small memorial erected to honor relating the material beneath the form as well as the Navy personnel killed in a plane crash in the draw in form: “fill terrace”, “fill-cut terrace”, and “strath 1946), arise on the piedmont below 1,880 m. terrace”, depending on whether the terrace is Memorial Draw covers about 19 km2 and Ojo de la underlain by thick fill, beveled fill, or thin fill on Cabra is less than 2.3 km2, but its drainage has bedrock. Paired terraces are interpreted to imply fluctuated in size and connectedness to mountain widespread or long-duration geomorphic episodes headwaters through time due to stream capture and related to tectonics and/or climatic regimes whereas piedmont progradation near the mouth of Sanchez unpaired terraces imply local, short-duration, perhaps Canyon drainage. Annual precipitation ranges from not climatically, tectonically, or alluvially significant about 200 mm at the lowest elevations to more than events. 500 mm in the headwaters. Precipitation intensity Geomorphologists have conventional ranges up to 150 mm per 24 hours (United States expectations of terraces. Generally terraces are Department of Commerce, 1973). At present, much preserved along margins of stream valleys. They of the small drainage basins appear not to experience commonly parallel modern stream gradients or they even decadal overland flow events. Channel gradients diverge downstream or converge downstream. range from 6 to 26 m/km (0.006 to 0.026). Hell Commonly terraces exhibit equal amounts of Canyon Arroyo ranges up to 40 m wide and 5 m deep preservation/degradation along reaches. They relate and is continuous from the mountains to the Rio to one kind of climatic regime (or sequence of Grande valley. Boulder bars along the valley floor regimes) during episodic downcutting and outside the arroyo attest to at least one large flood in aggradation. Holocene terraces along arroyos may the first half of the 20th century. Boulders along reflect discontinuous downcutting and backfilling tributaries suggest prehistoric high-discharge events (Schumm and Hadley, 1957) but such ephemeral that reworked adjacent Pleistocene deposits into events are not postulated for larger Pleistocene Holocene channels. All three drainages cross multiple terraces. Schumm and Parker (1973) also interpret strands of faults. Ojo de la Cabra and Memorial Draw terraces as products of complex response wherein cross strands of the Hubbell Spring fault zone and multiple terraces result from autogenic changes in lower Memorial Draw follows part of the main strand water and sediment discharges within a drainage of the McCormick Ranch fault. Hell Canyon crosses without external changes in climate, slope/base level, the Manzano fault zone, multiple strands of the or sediment availability. The terraces along Hell Hubbell Spring fault zone, McCormick Ranch fault Canyon and two of its tributaries do not exhibit these zone, and strands of the Palace-Pipeline fault zone. conventional phenomena. In fact, they fly in the face Downstream from the Western Hubbell Spring and of all common expectations. The terraces of Hell McCormick Ranch faults, Hell Canyon and Memorial Canyon drainages are described below after Draw are bordered with loose pebbly sand of the introducing the geomorphic fundamentals of the ancestral Rio Grande. Upstream, their borders are system. various ages of piedmont alluvium. Along the periphery of the drainage basins, eolian sand sheets GEOMORPHIC FUNDAMENTALS OF THE and dunes have disrupted tributary drainages so that HELL CANYON DRAINAGE very little runoff is contributed to the drainages themselves.

A-1 NMBGMR OFR454D

Figure 1. Figure 1. Longitudinal profile of Hell Canyon Wash from the Rio Grande floodplain to the upper piedmont (5900 ft) with terrace reaches and faults shown. Above the fold line is the stream profile, terrace levels, and faults viewed to the north. Below the fold line is the profile, terrace levels, and faults viewed to the south. Kinks in fault symbols portray oblique fault traces. To see differences between the north and south sides of Hell Canyon, fold the paper in half along the fold line and hold it up to strong light or copy the image onto a transparency and fold the two profiles together. Superimposing the two images will show not only the differences between the canyon sides, they will show that one image of both sides would be too complicated for illustrative purposes.

TERRACES some small tributaries and along fault scarps. Yet, springs are rare along the fault traces now (Hubbell Along these three drainages, geomorphologists Spring and Ojo de la Cabra) and the water table is may see many subtle stretches of tread surfaces (Fig. hundreds of feet below the surface along some stream 1), but the deposits and soils underneath the surfaces reaches. are not well exposed. Similar sub-terrace alluvial High “terraces” along the lower reach of Hell deposits occur at different terrace levels; conversely Canyon are only partially related to the drainage (Fig. terraces with different sub-terrace deposits and/or 1). The highest surface on the north side of the soils show up at the same height above the thalweg in drainage consists of uplifted and tilted gravelly sands different reaches. So-called “fill terraces” crop out deposited by the Rio Grande, only overtopped locally near the centers of drainages but these become strath by piedmont gravels on the downthrown sides of the terraces along the valley margins so the terms “fill” Palace-Pipeline fault zone. The south rim of the and “strath” are a matter of preservation, not lower reaches of Hell Canyon is capped with fundamental behavior. Terraces may be offset or piedmont gravel from the Manzanita Mountains and tilted by faulting, but without better correlation therefore could be considered a “terrace” relative to techniques, it is difficult to tell which surface is the inset drainage. Similarly, higher “terraces” along which across faults. Ephemeral eolian and alluvial Ojo de la Cabra and Memorial Draw are not related cover apparently affects soil development on parts of to the streams that currently are cut into them. Rather, terraces so that correlations based on soil some terraces are related to broader aggradational development are suspect. Finally, on both footwalls events related to Hell Canyon drainage before it and hanging walls of faults shallow, carbonate- became incised and to local tectonic movements. precipitating groundwater cemented the deposits and Such “terraces” are broad surfaces on one side of a made mounds near the faults and spread laterally and tributary (and therefore can not be termed “terraces”), longitudinally to form thin sheets and plates of but are inset against uplifted older surfaces on other calcium carbonate (micrite and sparite) both side. Terraces at similar levels (i.e. the highest levels) perpendicular and parallel to the ground surface. on different sides of faults in adjacent reaches may or Degraded spring mounds are not uncommon along may not be related. A-2 NMBGMR OFR454D Along Hell Canyon and Memorial Draw, some DISCUSSION AND CONCLUSIONS inset terraces become wider downstream and overtop the landscape, spreading out to become broad The terraces of Hell Canyon and its tributaries piedmont-like surfaces on both sides of the drainages clearly have a long and complicated history, which (Fig. 1). Strands of the Hubbell Spring fault zone cut remains to be figured out. Details will need to be some of these, particularly along Memorial Draw,; based on more than 10- and 40-foot contour maps others are unfaulted, but are high on the landscape and poor exposures in most reaches. The dynamic relative to Hell Canyon drainage and much higher shifts in stream entrenchment and episodic terrace than terraces inset in Hell Canyon. formation have taken place during the past million As one follows terraces upstream along years, ending up with the present incised drainage of Memorial Draw and Ojo de la Cabra, most of the Hell Canyon. One can not simply use the “finger terraces are very poorly preserved at their method” of counting terraces backward to correlate downstream ends, are discontinuous and highly with the climatic signal recorded by marine oxygen- eroded, and high on the valley sides in inset isotope stages because repeated motions on several positions. As the terraces are followed upstream, they faults have affected the terraces, the valley border become better preserved and less eroded, more sediments change downstream, and because the continuous, but still entrenched. Farther upstream terraces appear to be time-transgressive in part, or at they have Holocene alluvium and eolian sands on top least in their upstream preservation. The upstream of more gravelly alluvium. Even farther upstream, the preservation and disappearance of terraces imply terraces are unentrenched, occupied by a late either incomplete adjustment of the drainages to Holocene-historic channel and floodplain. New, episodic changes in climate and tectonism (threshold discontinuous, eroded terraces appear on the and process-duration phenomena) or dynamic shifts landscape above the Holocene drainageway. These in sediment transport within the upper contributary new terraces in turn become more continuous and parts of these small drainages. Is it possible for the then buried upstream. The higher discontinuous small, ephemeral tributary drainages arising on terrace of the lower Ojo de la Cabra canyon may be piedmont slopes to generate enough water and traced to the upper part of the drainage where it sediment discharge within one climatic regime to becomes buried by Holocene distal piedmont create a complex response to form more than one prograding from the east (in part from lower Sanchez terrace in a short period of time, or to generate more Canyon drainage) and eolian sand prograding across than one terrace longitudinally at the same time? the drainage from the southwest. Stay tuned. The upper part of Memorial Draw is incised into the Canada Colorada surface (Tsp on color map REFERENCES elsewhere in guidebook) as are similar ephemeral drainages to the north. These drainages have Bull, W. B., 1991, Geomorphic responses to climatic intermediate terraces inset below the level of the change: New York, Oxford University Press, 326 Canada Colorada and slightly lower piedmont p. surfaces. They also commonly have only a thin Jackson, J. A., 1997, Glossary of geology [Fourth edition]: American Geological Institute, 769 p. veneer of canyon-bottom Holocene alluvium resting Leopold, L. B., Wolman, M. G., and Miller, J. P., 1964, on well cemented Pleistocene conglomerate (not Fluvial processes in geomorphology, San older Tps or Qps; see color map) and groundwater- Francisco, W. H. Freeman, 522 p. related platy carbonates. The pervasive platy calcium Schumm, S. A., and Hadley, R. F., 1957, Arroyos and the carbonate cements both within the drainages and semiarid cycle of erosion, American Journal of along the valley borders suggest (perhaps wrongly) Science, v. 225, p. 161-174. that the drainages are relict from a time when the Schumm, S. A., and Parker, R. S. 1973, Implications of water table was high and that not much sediment complex response of drainage systems for transport or deposition has taken place in the past few Quaternary alluvial stratigraphy: Nature, Physical Science (London), v. 243, no. 128, p. 99-100. thousand years at least. The platy carbonate is United States Department of Commerce, 1973, commonly broken up and transported short distances Precipitation-frequency atlas of the Western downslope, making the shallow exposures difficult to United States, v. IV, New Mexico: National distinguish from degraded Stage IV pedogenic Oceanic and Atmospheric Administration, laminar carbonate. These platy carbonate clasts are National Weather Service, Atlas 2. particularly confusing in young fans along the hanging walls of faults, causing geomorphologists to question the age of the deposits on both sides of fault scarps.

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SURFACE GEOLOGY AND LIQUEFACTION SUSCEPTIBILITY IN THE INNER RIO GRANDE VALLEY NEAR ALBUQUERQUE, NEW MEXICO

Keith I. Kelson, Christopher S. Hitchcock, and Carolyn E. Randolph William Lettis & Associates, Inc. 1777 Botelho Drive, Suite 262 Walnut Creek, California 94596

INTRODUCTION photography and geologic mapping, supplemented by geotechnical borehole data compiled from existing Historic large earthquakes throughout the world databases and logs on file with municipal, state, and demonstrate that liquefaction-related ground failure federal agencies. The groundwater maps are based commonly causes extensive structural and lifeline on analysis of water-level data from well catalogs, damage in urbanized areas. Delineating areas that are the geotechnical borehole database, shallow drive- susceptible to liquefaction hazards is critical for point well data, and water-level elevations in evaluating and reducing the risk from liquefaction drainage ditches. through appropriate mitigation and emergency response. Because liquefaction generally occurs in FLOODPLAIN MATERIALS AND WATER- areas underlain by low-density, saturated granular TABLE DEPTHS sediments, liquefaction susceptibility can be mapped using specific, well established geologic and The inner Rio Grande valley is underlain geotechnical criteria. The inner Rio Grande valley primarily by saturated, unconsolidated sandy near Albuquerque is within the seismically active Rio alluvium deposited by the Rio Grande and tributary Grande rift, is underlain by saturated late Holocene arroyos (Fig. 1). This alluvium consists floodplain deposits, and thus is particularly predominantly of sand and gravel with discontinuous vulnerable to liquefaction hazards. The purpose of interbeds of silt and clay. Borehole data from these this study is to delineate areas of the inner Rio deposits show that most have low Standard Grande valley near Albuquerque that are susceptible Penetration Test (SPT) blow counts. The valley also to liquefaction (Kelson et al., 1999). The map contains levees, embankments and other man-made products developed in the study are useful for features composed of engineered and non-engineered insurers, engineers, planners, and emergency- artificial fill. Groundwater in the inner valley is very response personnel in order to properly assess and shallow, with depths beneath most of the valley of mitigate the risk from future liquefaction hazards in less than 12 m (40 ft) (Fig. 2). In this analysis, we the Albuquerque area. use the shallowest historic water level recorded, thus providing conservatively shallow water depths Methods throughout the inner valley. Because of historic declines in groundwater levels near downtown Our approach in delineating liquefaction Albuquerque, our analysis provides a conservative susceptibility in the Albuquerque area is to identify assessment of liquefaction susceptibility in areas that geologic units that are susceptible to liquefaction continue to experience water-level declines. Lesser based on surficial geologic mapping, evaluation of amounts of historic groundwater decline in the areas shallow groundwater depths, and analysis of north of Albuquerque (i.e., from Alameda to subsurface geotechnical data. These data sets are Bernalillo) and south of Albuquerque (i.e., from combined to produce a series of maps showing Armijo to Isleta Pueblo) suggest that liquefaction liquefaction susceptibility in the inner Rio Grande susceptibilities in these areas have not been affected valley. This report presents several 1:24,000-scale by groundwater withdrawals. maps of the inner valley that depict: (1) surficial geologic units, (2) depth to groundwater, and (3) LIQUEFACTION SUSCEPTIBILITY liquefaction susceptibility. The map area covers the inner Rio Grande valley from the Jemez River on the Based on our synthesis of the geologic, north to the Isleta Pueblo on the south, and includes geotechnical, and groundwater data, large areas of the parts of the Bernalillo, Alameda, Los Griegos, inner Rio Grande valley near Albuquerque are Albuquerque West, and Isleta 7.5-minute susceptible to liquefaction (Fig. 3). Areas underlain quadrangles. The geologic maps of the inner valley by deposits that may liquefy given a peak ground are based primarily on interpretation of aerial acceleration (PGA) of 0.1g or less, given the

B-1 NMBGMR OFR454-D occurrence of a magnitude 7.0 earthquake, are ACKNOWLEDGMENTS classified as having Very High susceptibility. In the inner valley, these areas include the saturated sandy This research was supported by U.S. Geological alluvium associated with the present-day channel and Survey (USGS), Department of the Interior, under active floodplain of the Rio Grande. Where USGS award number 98-HQ-GR-1009, for the groundwater is less than 9 m (30 ft), areas of artificial National Earthquake Hazard Reduction Program. fill associated with levees and embankments are The views and conclusions contained in this conservatively classified as having Very High document are those of the authors and should not be susceptibility. Areas classified as having High interpreted as necessarily representing the official susceptibility have groundwater depths of less than 9 policies, either expressed or implied, of the U.S. m (30 ft) and are underlain by sandy alluvium that Government. may liquefy with a PGA of 0.2g or less, given the occurrence of a magnitude 7.0 earthquake. Less REFERENCES extensive areas of the inner valley have deeper groundwater and / or are underlain by older, more Kelson, K.I., Hitchcock, C.S., and Randolph, C.E, consolidated deposits that are less susceptible to 1999, Liquefaction Susceptibility in the Inner liquefaction, and are classified as having Moderate or Rio Grande Valley Near Albuquerque, New Low susceptibility. Upland areas adjacent to the Mexico: unpublished final technical report, U.S. inner valley generally are classified as having a Low Geological Survey National Earthquake Hazards or Very Low susceptibility to liquefaction. Reduction Program, Award Number 98-HQ-GR- Overall, the areas classified as having a Very 1009, 40 p., 9 plates, scale 1:24,000. High or High liquefaction susceptibility include most of the inner Rio Grande valley. This area involves roughly 240 square kilometers (90 square miles) within the valley north and south of Albuquerque. Downtown Albuquerque is classified as having areas of High susceptibility (roughly southwest of the intersection of Silver Avenue and Sixth Street) and Moderate susceptibility (roughly southwest of the intersection of Marquette Avenue and First Street). The zones identified herein as Very High or High susceptibility encompass the areas most likely to experience liquefaction-related damage from a moderate to large earthquake in central New Mexico. Overall, it is reasonable to assume that large areas of the inner valley will be affected by liquefaction- related damage. Site-specific geotechnical investigations should be performed in areas of Very High or High susceptibility to assess risk to existing facilities and to evaluate and mitigate liquefaction hazards prior to future development.

B-2 NMBGMR OFR454-D

Figure 1. Surficial geologic map of part of the Albuquerque West quadrangle. Units designated by following notation; Q: Quaternary, Pleistocene, fp: floodplain, a: alluvium, ps: paleochannel, ol: overbank levee; pb: point bar; e: eolian, fy: young alluvial fan, fo: old alluvial fan, c: colluvium, af: artificial fill. Numerals indicate relative age of units, with 1=oldest and 4=youngest.

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Figure 2. Groundwater elevation map (dashed lines) and depth-to-groundwater contour map (solid lines) of part of Albuquerque West quadrangle. Data point from shallow boreholes, drainage ditches, and drive-point wells (Kelson et al., 1999).

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Figure 3. Liquefaction susceptibility of part of the Albuquerque West quadrangle (VH: Very high, H: High, M: Moderate, L: Low, VL: Very Low).

B-5 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B) STRATIGRAPHY OF MIDDLE AND UPPER PLEISTOCENE FLUVIAL DEPOSITS OF THE RIO GRANDE (POST-SANTA FE GROUP) AND THE GEOMORPHIC DEVELOPMENT OF THE RIO GRANDE VALLEY, NORTHERN ALBUQUERQUE BASIN, CENTRAL NEW MEXICO

SEAN D. CONNELL New Mexico Bureau of Mines and Mineral Resources-Albuquerque Office, New Mexico Institute of Mining and Technology, 2808 Central Ave. SE, Albuquerque, NM 87106

DAVID W. LOVE New Mexico Bureau of Mines and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801

INTRODUCTION units. Furthermore, these geomorphic (i.e., “-alto”) terms were imported by Lambert (1968) for Alluvial and fluvial deposits inset against Plio- geomorphic surfaces described by Bryan and Pleistocene deposits of the upper Santa Fe Group McCann (1936, 1938) in the upper Rio Puerco valley (Sierra Ladrones and Arroyo Ojito formations) record without careful comparison of soil-morphologic and the development of the Rio Grande valley (Fig. 1) in geomorphic character of deposits within each the northern part of the Albuquerque basin since drainage basin. Thus, these geomorphic terms may early Pleistocene time. These fluvial terrace deposits not be applicable in the Rio Grande valley without contain pebbly to cobbly sand and gravel with additional work to establish surface correlations abundant rounded quartzite, subordinate volcanic, across the Llano de Albuquerque, the interfluve and sparse plutonic clasts derived from northern New between the Rio Grande and Rio Puerco valleys. Mexico. Although the composition of the gravel in Fluvial deposits discussed in this paper are, in these deposits is similar, they can be differentiated increasing order of age, the Los Padillas, Arenal, Los into distinct and mappable formation- and member- Duranes, Menaul, Edith, and Lomatas Negras rank units on the basis of landscape-topographic formations. position, inset relationships, soil morphology, and Although these inset ancestral Rio Grande units height of the basal contact above the Rio Grande as may be classified and differentiated determined from outcrop and drillhole data (Table 1; allostratigraphically, we consider them as lithologic Connell and Love, 2000). These fluvial deposits units of formation- and member rank that can be overlie, and locally interfinger with, alluvial deposits differentiated on the basis of bounding derived from paleo-valley margins and basin margin unconformities, stratigraphic position, and lithologic uplands (Fig. 2). Constructional terrace treads are not character. commonly preserved in older deposits, but are locally Recent geologic mapping of the Albuquerque well preserved in younger deposits. area (Cather and Connell, 1998; Connell, 1997, 1998; Kirk Bryan (1909) recognized two distinct types Connell et al., 1998; Love, 1997; Love et al., 1998; of ancestral Rio Grande deposits, his older Rio Smith and Kuhle, 1998; Personius et al., 2000) Grande beds (now called upper Santa Fe Group), and delineate a suite of inset fluvial deposits associated his younger, inset Rio Grande gravels (post Santa-Fe with the axial-fluvial ancestral Rio Grande. Inset Group). Lambert (1968) completed the first detailed terrace deposits record episodic incision and partial geologic mapping of the Albuquerque area and aggradation of the ancestral Rio Grande during proposed the terms Los Duranes, Edith, and Menaul Pleistocene and Holocene time. Lack of exposure and formations for prominent fluvial terrace deposits preservation of terrace deposits between Galisteo associated with the ancestral Rio Grande, however, Creek and Las Huertas Creek hampers correlation to these terms were not formally defined. Lambert partially dated terrace successions at the northern (1968) correctly suggested that a higher and older margin of the basin and in White Rock Canyon unit (his Qu(?)g) may be an inset fluvial deposit of (Dethier, 1999; Smith and Kuhle, 1998), southward the ancestral Rio Grande (Tercero alto terrace of into Albuquerque; however, correlation of these units Machette, 1985). using soil-morphology, landscape position, and We informally adopt three additional stratigraphic relationships provide at least limited lithostratigraphic terms to clarify and extend local constraints on the Rio Grande terrace Lambert's inset Rio Grande stratigraphy. We propose stratigraphy. lithostratigraphic terms to these fluvial deposits Soil-morphologic information derived from principally to avoid confusion in the use of profiles for fluvial and piedmont deposits are geomorphic terms, such as the primero, segundo, and described on well preserved parts of constructional tercero alto surfaces (Lambert, 1968), for lithologic geomorphic surfaces (Connell, 1996). Carbonate

C-1 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B) morphology follows the morphogenetic classification buttress unconformity between this deposit and the system of Gile et al. (1966). underlying Arroyo Ojito Formation is exposed in the Loma Machete quadrangle (unit Qtag, Personius et al., 2000). The Lomatas Negras Formation is typically less than 16 ft (5 m) thick and consists of moderately consolidated and weakly cemented sandy pebble to cobble gravel primarily composed of subrounded to rounded quartzite, volcanic rocks, granite and sparse basalt (Fig. 3). This unit is discontinuously exposed along the western margin of the Rio Grande valley, where it is recognized as a lag of rounded quartzite-bearing gravel typically between about 215-245 ft (65-75 m) above the Rio Grande floodplain, which is underlain by the Los Padillas Formation (Fig. 4). The basal contact forms a low- relief strath cut onto slightly tilted deposits of the Arroyo Ojito Formation. The top is commonly eroded and is commonly overlain by middle Pleistocene alluvium derived from drainages heading in the Llano de Albuquerque. Projections of the base suggest that it is inset against early Pleistocene aggradational surfaces that define local tops of the Santa Fe Group, such as the Las Huertas and Sunport geomorphic surfaces (Connell et al., 1995, 1998; Connell and Wells, 1999; Lambert, 1968). Correlative deposits to the south (Qg(?) of Lambert, 1968) underlie the late-middle Pleistocene Figure 1. Shaded relief image of the northern part of (156±20 ka, Peate et al., 1996) Albuquerque the Albuquerque Basin (derived from U.S. Volcanoes basalt (Figs. 3-4). Projections of the Geological Survey 10-m DEM data) illustrating the Lomatas Negras Formation north of Bernalillo are approximate locations of terrace risers (hachured limited by the lack of preserved terraces, so, we lines), the Sunport surface (SP), stratigraphic sections provisionally correlate these highest gravel deposits (1-5), and cross section lines (A-F). with the Lomatas Negras Formation, recognizing the possibility that additional unrecognized terrace levels and deposits may be present along the valley margins. Similar deposits are recognized near Santo Domingo (Qta1 of Smith and Kuhle, 1998), which contain the ca. 0.66 Ma Lava Creek B ash from the Yellowstone area of Wyoming. A gravel quarry in the Pajarito Grant (Isleta quadrangle) along the western margin of the Rio Grande valley exposes an ash within an aggradation succession of fluvial sand and gravel. This ash has been geochemically correlated to the Lava Creek B (N. Dunbar, 2000, personal commun.) It lies within pebbly to cobbly sand and gravels that grade upward into a succession of sand with lenses of pebbly sand. This unit is Figure 2. Block diagram of geomorphic relationships slightly lower, at ~46 m above the Rio Grande, than among entrenched post-Santa Fe Group deposits Lomatas Negras deposits to the north, suggesting the along the western piedmont of the Sandia Mountains presence of additional unrecognized middle and east of the Rio Grande valley (from Connell and Pleistocene fluvial units, or intrabasinal faulting has Wells, 1999). down-dropped the Pajarito Grant exposures. The Lomatas Negras Formation is interpreted to be inset Lomatas Negras Formation against the Sunport surface, which contains a 1.26 Ma ash near the top of this Santa Fe Group section in The highest and presumably oldest preserved Rio Tijeras Arroyo. These stratigraphic and geomorphic Grande terrace deposit in the Albuquerque-Rio relationships indicate that the Lomatas Negras Rancho area is informally called the Lomatas Negras Formation was deposited between about 1.3 and 0.7 Formation for Arroyo Lomatas Negras, where a Ma.

C-2 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B)

Table 1. Summary of geomorphic, soil-morphologic, and lithologic data for ancestral Rio Grande fluvial, piedmont and valley border deposits, listed in increasing order of age.

Unit Height Thickness Carbonate Geomorphic/stratigraphic position above Rio (m) Morphology Grande (m) Qrp 0 15-24 0 Lowest inset deposit; inner valley floodplain. Qay 0-3 <21 0, I Inset against Qpm; grades to Qrp. Qra 15 3-6 II+ Primero alto surface, inset against Qrd. Qam, Qpm ~65, eroded 45 III Alluvial deposits west of Rio Grande valley; top Overlies Qrd. Qrd 44-48 6-52 II+ Segundo alto surface, inset against Qre Qpm 8-30 15-51 II+, III+ Piedmont deposits of Sandia Mts; east of Rio Grande valley; interfingers with Qrm. Qrm 26-36 3 II+ Overlies Qpm and Qre; may be correlative to part of Qrd. Qre 12-24, 3-12 not Inset against Qrl, inset by Qrd; underlies eroded top determined Qpm with stage III + carbonate morphology. Qao, Qpo ~100, eroded <30 III to IV Overlies Qrl; inset by Qpm and Qre. top Qrl ~46-75, 5-20 III, eroded Inset against Sunport surface. Contains ash eroded top correlated to the Lava Creek B. Las ~120 --- III+ Local top of Sierra Ladrones Formation Huertas SP ~95 --- III+ Sunport surface of Lambert (1968): youngest Santa Fe Group constructional basin-floor surface.

Edith Formation (Connell, 1996). The Edith Formation unconformably overlies tilted sandstone of the The Edith Formation is a 10-40 ft (3-12 m) thick Arroyo Ojito and Sierra Ladrones formations and is deposit that typically comprises a single upward overlain by piedmont alluvium derived from the fining sequence of basal gravel and overlying sandy Sandia Mountains (Fig. 5). Where the top of the to muddy floodplain deposits. The Edith Formation Edith Formation is preserved, it typically contains serves as a useful and longitudinally extensive weakly developed soils with Stage I carbonate marker along the eastern margin of the Rio Grande morphology. This weak degree of soil development valley, between Albuquerque and San Felipe Pueblo, suggests that deposition of piedmont and valley New Mexico. This fluvial deposit can be physically border fan sediments occurred shortly after correlated across 33 km, from its type area in deposition of the Edith Formation. Albuquerque (Lambert, 1968, p. 264-266 and p. 277- The Edith Formation contains Rancholabrean 280), to near Algodones, New Mexico (Lambert, fossils, most notably Bison, Mastodon, Camelops, 1968; Connell et al., 1995; Connell, 1998, 1997; and and Equus (Lucas et al., 1988). Lambert (1968) Cather and Connell, 1998). The Edith Formation is a considered the Edith Formation to represent a late poorly to moderately consolidated, locally cemented Pleistocene terrace deposited during the latest deposits of pale-brown to yellowish-brown gravel, Pleistocene glacial events. Soils developed in these sand and sandy clay that forms laterally extensive piedmont deposits exhibit moderately developed Bt outcrops along the inner valley escarpment of the Rio and Btk horizons with moderately thick clay films Grande. Commonly recognized as an upward-fining and Stage III+ carbonate morphology, suggesting a succession of a 7-26 ft (2-8 m) thick, basal quartzite- middle Pleistocene age for these deposits (Connell, rich, cobble gravel that grades up-section into a 13-32 1996; Connell and Wells, 1999). ft (4-10 m) thick succession of yellowish-brown sand The base of the Edith Formation forms a and reddish-brown mud. The upper contact is locally prominent strath that lies about 40-80 ft (12-24 m) marked by a thin, white diatomite between Sandia above the Rio Grande floodplain and is about 30 m Wash and Bernalillo. Gravel contains ~30% rounded higher than the base of the Los Duranes Formation quartzite and ~40% volcanic rocks with subordinate (Connell, 1998). The elevation of this basal strath is granite, metamorphic, and sandstone clasts, and lower than the base of the Lomatas Negras Formation sparse, rounded and densely welded Bandelier Tuff suggesting that the Edith Formation is inset against

C-3 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B)

Figure 3. Stratigraphic and drillhole sections of Pleistocene fluvial deposits of the ancestral and modern Rio Grande along the Rio Grande valley: 1) Los Padillas Formation at the Black Mesa-Isleta Drain piezometer nest; 2) Arenal Formation at Efren quarry (modified from Lambert, 1968; Machette et al., 1997); 3) Los Duranes Formation at the Sierra Vista West piezometer nest (data from Chamberlin et al., 1998); 4) Edith and Menaul formations at Sandia Wash (Connell, 1996); and 5) Lomatas Negras Formation at Arroyo de las Calabacillas and Arroyo de las Lomatas Negras. the Lomatas Negras Formation. A partially exposed piedmont deposits overlying the Edith Formation. buttress unconformity between eastern-margin Therefore, it is likely that the gravels underlying the piedmont alluvium and upper Santa Fe Group primero alto terrace are probably much younger than deposits marks the eastern extent of this unit. This the Edith Formation. Therefore, if the Edith unconformity is locally exposed in arroyos between Formation is older than the Los Duranes Formation Algodones and Bernalillo, New Mexico. (see below), it was deposited prior to about 100-160 Lambert (1968) recognized the unpaired nature ka. of terraces in Albuquerque, but assigned the Edith The Edith Formation may correlate to fluvial Formation to the topographically lower primero alto terrace deposits near Santo Domingo Pueblo (Smith terrace, which is underlain by the Los Duranes and Kuhle, 1998). Deposits at Santo Domingo Formation in SW Albuquerque. Lambert (1968) Pueblo are approximately 30-m thick and about 30- correlated the Edith Formation with the primero alto 35 m above the Rio Grande (Qta3 of Smith and terrace, and therefore interpreted it to be younger Kuhle, 1998). The lack of strongly developed soils than the Los Duranes Formation. The primero alto between the Edith Formation and interfingering terrace is the lowest fluvial-terrace tread in SW middle Pleistocene piedmont alluvium suggests that Albuquerque and is underlain by rounded pebbly the Edith Formation was deposited closer in time to sandstone that is inset against the Los Duranes the Los Duranes Formation. Thus, the Edith Formation. Soils on the primero alto terrace are Formation was deposited between 0.66 and 0.16 Ma, weakly developed (stage I to II+ carbonate and was probably laid down during the later part of morphology, Machette et al., 1997) compared to the middle Pleistocene.

C-4 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B) west of the Rio Grande. Kelley and Kudo (1978) Los Duranes Formation called this terrace the Los Lunas terrace, near Isleta Pueblo, however, we support the term Los Duranes The Los Duranes Formation of Lambert (1968) Formation as defined earlier by Lambert (1968). The is a 40-52 m fill terrace consisting of poorly to Los Duranes Formation represents a major moderately consolidated deposits of light reddish- aggradational episode that may have locally buried brown, pale-brown to yellowish-brown gravel, sand, the Edith Formation; however, the Edith Formation and minor sandy clay derived from the ancestral Rio could also possibly mark the base of the aggrading Grande and tributary streams. The base typically Los Duranes fluvial succession. buried by deposits of the Rio Grande floodplain (Los Padillas Formation) in the Albuquerque. The basal Menaul Formation(?) contact forms a low-relief strath approximately 20 ft (6 m) above the Rio Grande floodplain near The Menaul Formation of Lambert (1968) is Bernalillo, New Mexico (Figs. 3-4), where the Los generally less than 10 ft (3 m) thick and overlies Duranes Formation is eroded by numerous arroyos interfingering piedmont deposits that overlie the and is about 20-23 ft (6-7 m) thick. The basal contact Edith Formation. The Menaul Formation consists of is approximately 100 ft (30 m) lower than the base of poorly consolidated deposits of yellowish-brown the Edith Formation. The terrace tread on top of the pebble gravel and pebbly sand derived from the Los Duranes Formation (~42-48 m above the Rio ancestral Rio Grande. Rounded quartzite pebbles that Grande) is about 12-32 m higher than the top of the are generally smaller in size than pebbles and cobbles Edith Formation. Geologic mapping and comparison in the Edith Formation. The Menaul gravel forms of subsurface data indicate that the base of the Edith discontinuous, lensoidal exposures along the eastern Formation is about 20-25 m higher than the base of margin o the Rio Grande valley. The basal contact is Los Duranes Formation, suggesting that the Los approximately 85-118 ft (26-36 m) above the Rio Duranes is inset against the Edith. Just north of Grande floodplain. The Menaul Formation is Bernalillo, New Mexico, deposits correlated to the conformably overlain by younger, eastern-margin Los Duranes Formation (Connell, 1998) contain the piedmont alluvium exhibiting Stage II+ carbonate Rancholabrean mammal Bison latifrons (Smartt et morphology, and is inset by younger stream alluvium al., 1991, SW1/4, NE1/4, Section 19, T13N, R4E), that exhibits weakly developed soils, suggesting a which supports a middle Pleistocene age. The Los late Pleistocene age of deposition. Duranes Formation is also overlain by the 98-110 ka Soils on piedmont deposits overlying the Cat Hills basalt (Maldonado et al., 1999), and locally Menaul are generally similar to the Los Duranes buries flows of the 156±20 ka (Peate et al., 1996) Formation; however, differences in parent material Albuquerque volcanoes basalt. Thus deposition of the texture make soil-based correlations somewhat Los Duranes Formation ended between 160-100 ka, ambiguous. Similarities in height above the Rio near the end of the marine oxygen isotope stage 6 at Grande and soil development on the Los Duranes about 128 ka (Morrison, 1991). Formation and the Menaul Formation suggest that Near Bernalillo, the basal contact of the Los these two units may be correlative. Thus, the Menaul Duranes(?) Formation, exposed along the western Formation may be temporally correlative to the Los margin of the of the Rio Grande valley, is Duranes Formation, and is likely a member of this approximately 30 m lower than the basal contact of unit. These units may be associated with an the Edith Formation, which is well exposed along the aggradational episode, possibly associated with eastern margin of the valley. This western valley- aggradation of the Los Duranes, middle Pleistocene margin fluvial deposit was originally assigned to the piedmont alluvium. The Edith Formation may Edith Formation by Smartt et al. (1991), however, represent the base of a Los Duranes-Menaul these are interpreted to be younger inset deposits that aggradational episode during the late-middle are likely correlative to the Los Duranes Formation Pleistocene. The base Edith Formation is consistently (Connell, 1998; Connell and Wells, 1999). higher than the base of the Los Duranes Formation, The terrace tread (top) of the Los Duranes suggesting that the Edith is older; however, definitive Formation is locally called the segundo alto surface crosscutting relationships have not been in the Albuquerque area (Lambert, 1968; Hawley, demonstrated. 1996), where it forms a broad constructional surface

C-5 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B)

Figure 4. Simplified geologic cross sections across the Rio Grande valley, illustrating inset relationships among progressively lower fluvial deposits. Letters indicate location of profiles on Figure 1 and elevations of cross sections are in feet above mean sea level. See Table 1 for description of symbols. Unit QTs denotes upper Santa Fe Group deposits.

C-6 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B) Rio Grande systems tract of the Sierra Ladrones Formation (Connell, 1997, 1998; Connell et al., 1995; Maldonado et al., 1999; Smith and Kuhle, 1998). The top comprises the modern floodplain and channel of the Rio Grande. The Los Padillas Formation is 15-29 m thick and consists of unconsolidated to poorly consolidated, pale-brown, fine- to coarse-grained sand and rounded gravel with subordinate, discontinuous, lensoidal interbeds of fine-grained sand, silt, and clay derived from the Rio Grande. This unit is recognized in drillholes and named for deposits underlying the broad inner valley floodplain near the community of Los Padillas in SW Albuquerque (Connell et al., 1998; Connell and Love, 2000). Drillhole data indicate that the Los Padillas Formation commonly has a gravelly base and unconformably overlies the Arroyo Ojito Formation. This basal contact is locally cemented Figure 5. Stratigraphic fence of Edith Formation and with calcium carbonate. The Los Padillas Formation piedmont deposits exposed along eastern margin of is overlain, and interfingers with, late Pleistocene to the Rio Grande valley, between Sandia Wash and Holocene valley border alluvial deposits derived highway NM-165, illustrating stratigraphic from major tributary drainages. relationships among fluvial-terrace and piedmont Because this unit has not been entrenched by the deposits. Rio Grande, no age direct constraints are available for the base of the alluvium of the inner valley in the Arenal Formation study area. This deposit underlies a continuous and relatively broad valley floor that extends south from The lowest preserved terrace deposit is the the Albuquerque basin through southern New Arenal Formation, which was named for exposures Mexico, where radiocarbon dates indicate just west of the Arenal Main Canal in SW aggradation of the inner valley by early Holocene Albuquerque (Connell et al., 1998). The Arenal time (Hawley and Kottlowski, 1969; Hawley et al., Formation is 3-6 m thick and is inset against the Los 1976). The base of the Los Padillas Formation was Duranes Formation. The Arenal Formation consists probably cut during the last glacial maximum, which of poorly consolidated deposits of very pale-brown to is constrained at ~15-22 ka in the neighboring yellow sandy pebble to cobble gravel recognized Estancia basin, just east of the Manzano Mountains. along the northwestern margin of the Rio Grande (Allen and Anderson, 2000). Thus, the inner valley inner valley. Gravel clasts are primarily rounded alluvium was probably incised during the latest quartzite and subrounded volcanic rocks (welded tuff Pleistocene and aggraded during much of Holocene and rare pumice) with minor granite. Soil time. Near the mouth of Tijeras Arroyo, charcoal was development is very weak, with Stage I to II+ recovered from about 2-3 m below the top of a valley carbonate morphology (Machette et al., 1997; border fan that prograded across the Los Padillas Machette, 1985). The top of the Arenal Formation is Formation and forms a broad valley border fan than the primero alto surface of Lambert (1968), which is has pushed the modern Rio Grande to the western 15-21 m above the Rio Grande. This deposit is not edge of its modern (inner) valley. This sample correlative to the Edith Formation as originally yielded a radiocarbon date of about 4550 yrs. BP interpreted by Lambert. This unit is interpreted to (Connell et al., 1998), which constrains the bulk of have been deposited during late Pleistocene time, deposition of the Los Padillas Formation to middle probably between about 71-28 ka. Holocene and earlier.

Los Padillas Formation EVOLUTION OF THE RIO GRANDE VALLEY

The Las Padillas Formation underlies the modern Santa Fe Group basin-fill deposits of the Rio Grande valley and floodplain and is interpreted ancestral Rio Grande generally differ in the scale and to represent the latest incision/aggradation phase of thickness relative to younger inset deposits, which the Rio Grande, which was probably deposited were deposited in well defined valley. During during latest Pleistocene-Holocene time. The Rio widespread aggradation of the basin (Santa Fe Group Grande floodplain (inner valley) ranges 3-8 km in time), the ancestral Rio Grande intimately width in most places and occupies only a portion of interfingered with piedmont deposits derived from the 10-12 km maximum width of the entire ancestral rift-margin uplifts, such as the Sandia Mountains

C-7 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B) (Connell and Wells, 1999; Maldonado et al., 1999). by about 7 m down to the west near Bernalillo Field and age relationships in the near Santa Ana (Connell, 1996). Between cross sections B-B’ and C- Mesa also indicate that the ancestral Rio Grande also C’ of Figure 4, the basal contact of the Edith interfingered with fluvial deposits correlated with the Formation is down-dropped to the south by about 15 Arroyo Ojito Formation (Cather and Connell, 1998). m by the northwest-trending Alameda structural During development of the Rio Grande valley (post- zone. This decrease in height above local base level Santa Fe Group time), the Rio Grande cut deeply into is also recognized by a change in stratigraphic older basin-fill, typically leaving large buttress positions relative to piedmont deposits to the east. unconformities between inset deposits and older Younger piedmont alluvium (Qay, Fig. 2) is typically basin fill of the upper Santa Fe Group (Fig. 8). found overlying the Edith Formation south of the Younger late Pleistocene-Holocene alluvial Alameda structural zone (East Heights fault zone), a deposits are commonly confined in arroyo channels zone of flexure or normal faults that displace the cut into older piedmont deposits east of the Rio Edith Formation in a down-to-the-southwest sense. Grande valley. These deposits commonly form valley North of the Alameda zone, tributary stream deposits border alluvial fans along bluffs cut by a meandering are inset against the Edith Formation and are found in Rio Grande. These fans commonly prograde across well defined valleys (see map by Connell, 1997). floodplain and channel deposits in the inner valley. The present discharge is inadequate to transport sediment out of the valley. The presence of progressively inset fluvial deposits along the margins of the modern valley indicates that episodes of prolonged higher discharge were necessary to flush sediment and erode the valley. Such episodes must have occurred prior to aggradation of valley fills, such as these fluvial terrace deposits. Progradation of middle Holocene tributary valley border fans across the modern Rio Grande floodplain suggests that deposition of tributary and piedmont facies occurred during drier (interglacial) conditions. Deposition of fluvial terraces in semi-arid regions probably occurred during the transition from wetter to drier climates (Schumm, 1965; Bull, 1991). The lack of strong soils between the terrace deposits of the ancestral Rio Grande and piedmont and valley border deposits suggests that piedmont and valley border deposition occurred soon after the development of major fluvial terrace deposits. Age constraints for the Los Duranes Formation indicate that aggradation of fluvial deposits occurred near the end of glacial periods. If we extrapolate ages based on this model of terrace development, then we can provide at least a first order approximation for Figure 6. Correlation of fluvial deposits inferred ages of other poorly dated terrace deposits throughout ages. The age of the top of the Los Duranes the study area (Fig. 6). The age of the Edith Formation is constrained by middle and late Formation is still rather poorly constrained. The Pleistocene basalt flows. The Lomatas Negras Edith Formation is Rancholabrean in age and older Formation contains the middle Pleistocene Lava than the Los Duranes Formation, suggesting that the Creek B ash. The Edith Formation contains middle- Edith may have been deposited sometime during late Pleistocene Rancholabrean fossils and is older MOIS 8, 10, or 12. The lack of strongly developed than the Los Duranes Formation, however, its precise soils on the top of the Edith Formation suggests that age is not well constrained. Younger deposits are deposition of this unit occurred closer in time to the constrained by a radiocarbon date of 4550 yr. BP. Los Duranes Formation. The Edith Formation is interpreted to be older than Correlation of these deposits and provisional age the Los Duranes Formation and precise than the constraints indicate that the ancestral positions of the Lomatas Negras Formation. More precise age control Rio Grande have been modified by tectonic activity has not been established and the Edith Formation (Fig. 7). Most notably, the Edith Formation, which could have been deposited during different climatic forms a nearly continuous outcrop band from episodes. Albuquerque just south of San Felipe, New Mexico, is faulted. The Bernalillo fault displaced this deposit

C-8 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B)

Figure 7. Generalized cross section across part of the piedmont of the Sandia Mountains, illustrating interfingering relationships among aggrading sediments of the upper Santa Fe Group, and inset post-Santa Fe Group deposits. Pedogenic carbonate morphology of constructional deposit surfaces is indicated by roman numerals that indicate the morphogenetic stage of soil development.

Figure 8. Longitudinal profile along Rio Grande, illustrating inset relationships among ancestral Rio Grande terraces and early Pleistocene aged constructional surfaces that locally mark the end of Santa Fe Group deposition (Las Huertas and Sunport geomorphic surfaces). The Edith and Los Duranes formations are deformed by northwest- trending faults that alter the elevation of the basal contact of these two units.

During late Pliocene time, the ancestral Rio of entrenchment were followed by periods of partial Grande formed an axial-river that flowed within a backfilling of the valley and progradation of few kilometers of the western front of the Sandia piedmont and valley border deposits (Figs. 9c and Mountains (Fig. 9a). During early Pleistocene time, 9d). The latest episode of entrenchment and partial between about 1.3-0.7 Ma, the Rio Grande began to backfilling occurred during the latest Pleistocene, entrench into the basin fill, just west of the modern when middle Pleistocene tributary deposits were valley. Piedmont deposits prograded across much of abandoned during entrenchment, and valleys partially the piedmont-slope of the Sandia Mountains and aggraded later during latest Pleistocene and Holocene buried these basin-fill fluvial deposits (Fig. 9b). time (Fig. 9e). During middle Pleistocene time, the Rio Grande episodically entrenched into older terrace deposits and basin-fill of the Santa Fe Group. These episodes

C-9 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B)

Figure 9. Paleogeographic maps of the latest phase of basin filling of the Santa Fe Group, and Pleistocene development of the Rio Grande valley (modified from Connell, 1996). Las Huertas Creek (LHC), Pino Canyon (PC), and del Agua Canyon (dAC) are shown for reference.

C-10 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B) REFERENCES West 7.5-minute quadrangle, Bernalillo County, New Mexico: New Mexico Bureau of Mines and Allen, B.D., and Anderson, R.Y., 2000, A Mineral Resources, Open-File Digital Geologic continuous, high-resolution record of late Map 17, scale 1:24,000. Pleistocene climate variability from the Estancia Dethier, D.P., 1999, Quaternary evolution of the Rio Basin, New Mexico: Geological Society of Grande near Cochiti Lake, northern Santo America Bulletin, v. 112, n. 9, p. 1444-1458. Domingo basin, New Mexico: New Mexico Bryan, K., 1909, Geology of the vicinity of Geological Society, Guidebook 50, p. 371-378. Albuquerque: University of New Mexico, Gile, L. H., Peterson, F. F. and Grossman, R. B., Bulletin No. 3, 24 p. 1966, Morphological and genetic sequences of Bull, W.B., 1991, Geomorphic responses to climate carbonate accumulation in desert soils: Soil changes: New York, Oxford University Press, Science, v. 101, n. 5, p. 347-360. 326 p. Hawley, J. W., 1996, Hydrogeologic framework of Cather, S.M., and Connell, S.D., 1998, Geology of potential recharge areas in the Albuquerque the San Felipe 7.5-minute quadrangle, Sandoval Basin, central New Mexico: New Mexico Bureau County, New Mexico: New Mexico Bureau of of Mines and Mineral Resources, Open-file Mines and Mineral Resources, Open-File Digital Report 402 D, Chapter 1, 68 p. Geologic Map 19, scale 1:24,000. Hawley, J.W. and Kottlowski, F.E., 1969, Quaternary Chamberlin, R.M., Jackson, P., Connell, S.D., geology of the south-central New Mexico border Heynekamp, M., and Hawley, J.W., 1999, Field region: New Mexico Bureau of Mines and logs of borehole drilled for nested piezometers, Mineral Resources, Circular 104, p. 89-115. Sierra Vista West Park Site: New Mexico Hawley, J.W., Bachman, G.O. and Manley, K., 1976, Bureau of Mines and Mineral Resources Open- Quaternary stratigraphy in the Basin and Range File Report 444B, 30 p. and Great Plains provinces, New Mexico and Connell, S.D., 1996, Quaternary geology and western Texas; in Mahaney, W.C., ed., geomorphology of the Sandia Mountains Quaternary stratigraphy of North America: piedmont, Bernalillo and Sandoval Counties, Stroudsburg, PA, Dowden, Hutchinson, and central New Mexico: New Mexico Bureau of Ross, Inc., p. 235-274. Mines and Mineral Resources Open-File Report Johnson, P.S., Connell, S.D., Allred, B., and Allen, 425, 414 p., 3 pls. B.D., 1996, Field logs of boreholes for City of Connell, S.D., 1997, Geology of the Alameda 7.5- Albuquerque piezometer nests, Hunters Ridge minute quadrangle, Bernalillo County, New Park, May 1996: New Mexico Bureau of Mines Mexico: New Mexico Bureau of Mines and and Mineral Resources, Open-File Report 426C, Mineral Resources, Open-File Digital Geologic 25 p., 1 log, 1 fig. Map 10, scale 1:24,000. Johnson, P.S., Connell, S.D., Allred, B., and Allen, Connell, S.D., 1998, Geology of the Bernalillo 7.5- B.D., 1996, Field logs of boreholes for City of minute quadrangle, Sandoval County, New Albuquerque piezometer nests, West Bluff Park, Mexico: New Mexico Bureau of Mines and July 1996: New Mexico Bureau of Mines and Mineral Resources, Open-File Digital Geologic Mineral Resources, Open-File Report 426D, 19 Map 16, scale 1:24,000. p., 1 log, 1 fig. Connell, S.D., and Love, D.W., 2000, Stratigraphy of Kelley, V. C. and Kudo, A. M., 1978, Volcanoes and Rio Grande terrace deposits between San Felipe related basaltic rocks of the Albuquerque-Belen Pueblo and Los Lunas, Albuquerque Basin, New Basin, New Mexico: New Mexico Bureau Mines Mexico [abstract]: New Mexico Geology, v. 22, Mineral Resources, Circular 156, 30 p. n. 2, p. 49. Lambert, P.W., 1968, Quaternary stratigraphy of the Connell, S.D., and Wells, S.G., 1999, Pliocene and Albuquerque area, New Mexico: [Ph.D. Quaternary stratigraphy, soils, and dissertation] Albuquerque, University of New geomorphology of the northern flank of the Mexico, 329 p. Sandia Mountains, Albuquerque Basin, Rio Love, D. W., 1997, Geology of the Isleta 7.5-minute Grande rift, New Mexico: New Mexico quadrangle, Bernalillo and Valencia Counties, Geological Society, Guidebook 50, p. 379-391. New Mexico: New Mexico Bureau of Mines and Connell, S.D., and 10 others, 1995, Geology of the Mineral Resources, Open-file Digital Geologic Placitas 7.5-minute quadrangle, Sandoval Map 13, scale 1:24,000. County, New Mexico: New Mexico Bureau of Love, D., Maldonado, F., Hallett, B., Panter, K., Mines and Mineral Resources, Open-File Digital Reynolds, C., McIntosh, W., Dunbar, N., 1998, Map 2, scale 1:12,000 and 1:24,000, revised Geology of the Dalies 7.5-minute quadrangle, Sept. 9, 1999. Valencia County, New Mexico: New Mexico Connell, S.D., Allen, B.D., Hawley, J.W., and Bureau of Mines and Mineral Resources, Open- Shroba, R., 1998, Geology of the Albuquerque file Digital Geologic Map 21, scale 1:24,000.

C-11 NMBGMR OFR454C (reprinted from NMBMMR OFR 454B) Lucas, S.G., Williamson, T.E., and Sobus, J., 1988, Peate, D.W., Chen, J.H., Wasserburg, G.J., and Late Pleistocene (Rancholabrean) mammals Papanastassiou, D.A., 1996, 238U-230Th dating of from the Edith Formation, Albuquerque, New a geomagnetic excursion in Quaternary basalts of Mexico: The New Mexico Journal of Science, v. the Albuquerque volcanoes field, New Mexico 28, n. 1, p. 51-58. (USA): Geophysical Research Letters, v. 23, n. Machette, M.N., 1985, Calcic soils of the 17, p. 2271-2274. southwestern United States: Geological Society Personius, S. F., Machette, M. N., and Stone, B. D., of America, Special Paper 203, p. 1-42. 2000, Preliminary geologic map of the Loma Machette, M.N., Long, T., Bachman, G.O., and Machette quadrangle, Sandoval County, New Timbel, N.R., 1997, Laboratory data for calcic Mexico: U.S. Geological Survey, Miscellaneous soils in central New Mexico: Background Field Investigations, MF-2334, scale 1:24,000, information for mapping Quaternary deposits in ver. 1.0. the Albuquerque Basin: New Mexico Bureau of Schumm, S.A., 1965, Quaternary paleohydrology, in Mines and Mineral Resources, Circular 205, 63 Wright, H.E., and Frey, D.G., eds, The p. Quaternary of the United States: New Jersey, Maldonado, F., Connell, S.D., Love, D.W., Grauch, Princeton University Press, p. 783-794. V.J.S., Slate, J.L., McIntosh, W.C., Jackson, Smith, G.A. and Kuhle, A.J., 1998, Geology of the P.B., and Byers, F.M., Jr., 1999, Neogene Santo Domingo Pueblo 7.5-minute quadrangle, geology of the Isleta Reservation and vicinity, Sandoval County, New Mexico, New Mexico Albuquerque Basin, New Mexico: New Mexico Bureau of Mines and Mineral Resources, Open- Geological Society Guidebook 50, p. 175-188. file Digital Geologic Map 15, scale 1:24,000.

C-12 NMBGMR OFR454D (reprinted from NMBMMR OFR 454B) SUMMARY OF BLANCAN AND IRVINGTONIAN (PLIOCENE AND EARLY PLEISTOCENE) MAMMALIAN BIOCHRONOLOGY OF NEW MEXICO

GARY S. MORGAN and SPENCER G. LUCAS New Mexico Museum of Natural History, 1801 Mountain Road NW, Albuquerque, NM 87104

Significant mammalian faunas of Pliocene (latest Mountain LF from the Jornada basin. These faunas Hemphillian and Blancan) and early Pleistocene are characterized by the presence of taxa absent from (early and medial Irvingtonian) age are known from early Blancan faunas, including Geomys the Rio Grande and Gila River valleys of New (Nerterogeomys) paenebursarius, Equus cumminsii, Mexico. Fossiliferous exposures of the Santa Fe E. scotti, and Camelops, and the absence of South Group in the Rio Grande Valley, extending from the American immigrant mammals found in late Blancan Española basin in northern New Mexico to the faunas. The Pajarito LF is directly associated with a Mesilla basin in southernmost New Mexico, have fluvially recycled pumice dated at 3.12±0.10 Ma produced 21 Blancan and six Irvingtonian vertebrate (Maldonado et al., 1999). The Cuchillo Negro Creek assemblages (Fig. 1). A medial Irvingtonian fauna is and Elephant Butte Lake LFs are in close known from a cave deposit in the San Luis basin in stratigraphic association with a basalt flow dated at northernmost New Mexico (Fig. 2). Three Blancan 2.9 Ma. Magnetostratigraphy constrains the age of faunas occur in Gila Group strata in the Gila River the Tonuco Mountain LF between 3.6 and 3.0 Ma. Valley in the Mangas and Duncan basins in The Mesilla A fauna from the Mesilla basin and southwestern New Mexico (Fig. 3). More than half of the Pearson Mesa LF from the Duncan basin are late these faunas contain five or more species of Blancan in age (2.7-2.2 Ma). Both faunas record the mammals, and many have associated radioisotopic association of Nannippus with a South American dates and/or magnetostratigraphy, allowing for immigrant, Glyptotherium from Mesilla A and correlation with the North American land-mammal Glossotherium from Pearson Mesa, restricting their biochronology (Figs. 2-3). age to the interval after the beginning of the Great Two diverse early Blancan (4.5-3.6 Ma) faunas American Interchange at about 2.7 Ma and before the are known from New Mexico, the Truth or extinction of Nannippus at about 2.2 Ma. Consequences Local Fauna (LF) from the Palomas Magnetostratigraphy further constrains the Mesilla A basin and the Buckhorn LF from the Mangas basin. and Pearson Mesa faunas to the upper Gauss Chron, The Truth or Consequences LF contains five species just prior to the Gauss/Matuyama boundary at 2.58 of mammals indicative of the early Blancan: Ma. The Mesilla B and Virden faunas occur higher in Borophagus cf. B. hilli, Notolagus lepusculus, the same stratigraphic sequences as the Mesilla A and Neotoma quadriplicata, Jacobsomys sp., and Pearson Mesa faunas, respectively, and are latest Odocoileus brachyodontus. Associated Blancan in age (2.2-1.8 Ma). Both faunas contain magnetostratigraphic data suggest correlation with taxa restricted to the Blancan, including the camels either the Nunivak or Cochiti subchrons of the Blancocamelus and Gigantocamelus from Mesilla B, Gilbert Chron (between 4.6 and 4.2 Ma), which is and Canis lepophagus from Virden. The absence of consistent with the early Blancan age indicated by the Nannippus, and of Mammuthus and other genera that mammalian biochronology. The Truth or first appear in the Irvingtonian, suggest an age range Consequences LF is similar in age to the Verde LF between 2.2 and 1.8 Ma. Magnetostratigraphic data from Arizona, and slightly older than the Rexroad 3 from Mesilla B support a latest Blancan age. and Fox Canyon faunas from Kansas. The Buckhorn The Tijeras Arroyo fauna from the Albuquerque LF has 18 species of mammals, including two rodents basin and the Tortugas Mountain and Mesilla C typical of the early Blancan, Mimomys poaphagus faunas from the Mesilla basin all include Mammuthus and Repomys panacaensis. The Buckhorn LF also is and other mammals indicative of an early similar in age to the Verde LF and has affinities with Irvingtonian age (1.8-1.0 Ma). The association of the Panaca LF from Nevada. Although the Buckhorn Mammuthus and Stegomastodon in the Tortugas and Truth or Consequences LFs have few taxa in Mountain LF indicates an age younger than 1.8 Ma, common, the similarities of both faunas with the after the arrival of Mammuthus in North America Verde LF suggest they are close in age. from Eurasia and before the extinction of Eight faunas from the central and southern Rio Stegomastodon at about 1.2 Ma. The co-occurrence Grande Valley are medial Blancan in age (3.6-2.7 of Glyptotherium arizonae, Equus scotti, and the Ma), including the Pajarito and Belen faunas from the primitive mammoth M. meridionalis in Tijeras Albuquerque basin, the Arroyo de la Parida LF from Arroyo and Mesilla C is typical of southwestern early the Socorro basin, the Cuchillo Negro Creek and Irvingtonian faunas. Fossils of M. meridionalis from Elephant Butte Lake LFs from the Engle basin, the Tijeras Arroyo and Mesilla C are both closely Palomas Creek LF from the Palomas basin, the Hatch associated with dates of 1.6 Ma on pumice from the LF from the Hatch-Rincon basin, and the Tonuco lower Bandelier tuff, making them among the oldest D-1 NMBMMR OFR 454D dated mammoths in North America. San Antonio advanced species of Allophaiomys, Lemmiscus Mountain (SAM) Cave in northernmost New Mexico curtatus, and Microtus cf. M. californicus indicates a lacks large mammals, but the presence of the medial Irvingtonian age, between about 1.0 and 0.85 microtine rodents Mictomys kansasensis, an Ma.

Figure 1. Map of New Mexico showing the location of late Hemphillian, Blancan, and Irvingtonian fossil sites. The structural basins are named and indicated by stippling. Sites are numbered from north to south in the Rio Grande Valley (sites 1-29), followed by sites in the Gila River Valley (sites 30-33). 1. San Antonio Mountain (SAM) Cave, medial Irvingtonian; 2. Puyé Formation site, late Hemphillian; 3. Ancha Formation sites, late Blancan; 4. Santo Domingo, late Blancan; 5. Western Mobile, early Irvingtonian; 6. Loma Colorado de Abajo, early/medial Blancan; 7. Mesa del Sol, Blancan; 8. Tijeras Arroyo, early Irvingtonian; 9. Pajarito, medial Blancan; 10. Isleta, Blancan; 11. Los Lunas, Blancan; 12. Belen, medial Blancan; 13. Mesas Mojinas, Blancan; 14. Veguita, Blancan; 15. Sevilleta, Blancan; 16. Arroyo de la Parida, medial Blancan; 17. Fite Ranch, early Irvingtonian; 18. Silver Canyon, Blancan; 19. Elephant Butte Lake, medial Blancan; 20. Cuchillo Negro Creek, medial Blancan; 21. Truth or Consequences, early Blancan; 22. Palomas Creek, medial Blancan; 23. Hatch, medial Blancan; 24. Rincon Arroyo, late Blancan/early Irvingtonian; 25. Tonuco Mountain, medial Blancan; 26. Tortugas Mountain, early Irvingtonian; 27. Mesilla A, late Blancan; 28. Mesilla B, latest Blancan; 29. Mesilla C, early Irvingtonian; 30. Buckhorn, early Blancan; 31. Walnut Canyon, latest Hemphillian; 32. Pearson Mesa, late Blancan; 33. Virden, latest Blancan.

D-2 NMBMMR OFR 454D

D-3 NMBMMR OFR 454D

Figure 2. Correlation chart showing the relative ages of late Hemphillian, Blancan, and Irvingtonian vertebrate faunas from the northern and central Rio Grande Valley in New Mexico, including the San Luis, Española, Albuquerque, Socorro, Engle, and Palomas basins. The chronological limits of the mammalian faunas are indicated by the vertical height of the boxes enclosing the fauna or site names. The lithostratigraphic unit from which each fauna or site was derived is also indicated within the box. The magnetochronology is from Berggren et al. (1995). Three different systems for subdividing the Blancan NALMA are indicated on the left side of the chart (Tedford, 1981; Repenning, 1987; Woodburne and Swisher, 1995).

D-4 NMBMMR OFR 454D

Figure 3. Correlation chart showing the relative ages of late Hemphillian, Blancan, and Irvingtonian vertebrate faunas from the southern Rio Grande Valley and Gila River Valley in New Mexico, including the Hatch-Rincon, Jornada, Mesilla, Mangas, and Duncan basins. Other notes as for Figure 2.

REFERENCES Repenning, C. A., 1987, Biochronology of the microtine rodents of the United States; in M. Berggren, W. A., Hilgen, F. J., Langereis, C. G., O. Woodburne, ed., Cenozoic mammals of Kent, D. V., Obradovich, J. D., Raffi, I., North America: Geochronology and Raymo, M. E., and Shackleton, N. J., 1995, biostratigraphy: University of California Late Neogene chronology: New perspectives Press, Berkeley, p. 236-268. in high-resolution stratigraphy: Geological Tedford, R. H., 1981, Mammalian biochronology of Society of America Bulletin, v. 107, p. the late Cenozoic basins of New Mexico: 1272-1287. Geological Society of American Bulletin, Maldonado, F., Connell, S.D., Love, D.W., Grauch, Part I, v. 92, p. 1008-1022. V.J.S., Slate, J.L., McIntosh, W.C., Jackson, Woodburne, M. O. and Swisher, C. C., III, 1995, P.B., and Byers, F.M., Jr., 1999, Neogene Land mammal high-resolution geology of the Isleta Reservation and geochronology, intercontinental overland vicinity, Albuquerque Basin, New Mexico: dispersals, sea level, climate, and vicariance: New Mexico Geological Society Guidebook SEPM Special Publication 54, p. 335-364. 50, p. 175-188.

D-5 NMBGMR OFR454D (reprinted from NMBMMR 454B) PLIO-PLEISTOCENE MAMMALIAN BIOSTRATIGRAPHY AND BIOCHRONOLOGY AT TIJERAS ARROYO, BERNALILLO COUNTY, NEW MEXICO

SPENCER G. LUCAS and GARY S. MORGAN New Mexico Museum of Natural History and Science, 1801 Mountain Rd. NW, Albuquerque, NM 87104

Most of the vertebrate fossils from Tijeras The land tortoise Hesperotestudo and five Arroyo, located just south of the Albuquerque species of mammals, including Glyptotherium cf. G. International Airport in Bernalillo County, are arizonae, Equus scotti, Equus sp., Camelops sp., and derived from the Sierra Ladrones Formation and are Mammuthus meridionalis occur together in the early Irvingtonian in age (Lucas et al., 1993). Tijeras Arroyo section above the Blancan site (l- However, one locality (New Mexico Museum of 1458) discussed above (Lucas et al., 1993; Morgan Natural History and Science [NMMNH] site L-1458) and Lucas, 2000). These species constitute a fairly at the base of the exposed stratigraphic section in typical fauna of early Irvingtonian age. Three Tijeras Arroyo (Fig. 1) has produced two species that additional species of mammals, a small species of are indicative of a Blancan age. The fossils from this Equus, the llama Hemiauchenia macrocephala and site were derived from a sandstone comprising unit 1 the mammoth Mammuthus imperator, occur in the stratigraphic section of Lucas et al. (1993, fig. somewhat higher in the Tijeras Arroyo section than 2). The lowermost part of the section in Tijeras the remainder of the fauna, but probably are Arroyo, including unit 1, was recently referred to the Irvingtonian as well. Ceja Member of the Arroyo Ojito Formation A caudal osteoderm of a glyptodont from Tijeras (Connell and Hawley, 1998; Connell et al., 1999). Arroyo (Lucas et al., 1993) probably is not diagnostic Both mammals identified from site L-1458 at the species level, although this specimen almost in the Tijeras Arroyo section, Hypolagus cf. H. certainly represents Glyptotherium arizonae. gidleyi and Equus cf. E. cumminsii, are typical of Tentative referral of this osteoderm to G. arizonae is Blancan faunas, and do not occur in the Irvingtonian. reasonable as its association with Mammuthus rules The extinction in the late Pliocene (about 2.2 Ma) of out a Blancan age, and the Rancholabrean G. several characteristic Blancan genera, including floridanum is restricted to the Atlantic and Gulf Hypolagus, Borophagus, Rhynchotherium, and coastal plains (Gillette and Ray, 1981). The large Nannippus, is considered one of the most important horse Equus scotti is the most common mammal in biochronological events in the late Blancan (Lindsay the Tijeras Arroyo Irvingtonian fauna, represented by et al., 1984). The presence of Hypolagus thus mandibles, isolated teeth, and postcrania (Lucas et indicates that site L-1458 is older than 2.2 Ma. Equus al., 1993; Morgan and Lucas, 2000). E. scotti is the cf. E. cumminsii appears to be absent from early typical large horse in late Blancan and early Blancan faunas, so L-1458 is probably middle or Irvingtonian faunas in the southwestern United States early late Blancan in age. (Hibbard and Dalquest, 1966), and occurs in medial Ten stratigraphically higher localities in Tijeras Blancan through early Irvingtonian faunas in New Arroyo have produced a significant vertebrate fauna Mexico (Tedford, 1981; Morgan et al., 1998). A of early Irvingtonian age (Lucas et al., 1993; Morgan complete equid metacarpal from Tijeras Arroyo is and Lucas, 2000). More than 75 m of the Sierra more slender than metacarpals of E. scotti, and Ladrones Formation are exposed in Tijeras Arroyo, represents a second, smaller species of Equus consisting of sandstones, pumiceous sandstones, and (Hibbard and Dalquest, 1966; Harris and Porter, gravels, with minor amounts of mudstone and 1980). A partial skull of a small Equus occurs higher diatomite. These sediments represent axial river in the Tijeras Arroyo section. deposits of an ancestral Rio Grande. The most Lucas and Effinger (1991) and Lucas et al. distinctive lithologic chracteristic of these beds is the (1993) referred a mandible with left and right m3 presence of reworked Guaje Pumice derived from the from Tijeras Arroyo to the primitive mammoth Bandelier Tuff, Ar/Ar dated at 1.61 Ma (Izett and Mammuthus meridionalis on the basis of its low plate Obradovich, 1994), in the units associated with an count and extremely thick enamel. This is one of only Irvingtonian fauna (units 3-8 of Lucas et al., 1993). two records of mammoths from New Mexico referred An extensive flora of leaves and pollen from a to M. meridionalis, indicating that this fauna is localized volcanic ash bed was collected in the almost certainly early Irvingtonian. The other record Tijeras Arroyo section (NMMNH Site L-1445). The consists of several partial teeth, tentatively referred to Tijeras Arroyo flora indicates that the cottonwood M. meridionalis, from an early Irvingtonian fauna in forest or bosque currently found along the banks of the Mesilla basin (Vanderhill, 1986). Lucas et al the Rio Grande in New Mexico dates back to at least (1993) referred a left M3 in a maxillary fragment the early Pleistocene (Knight et al., 1996). from Tijeras Arroyo to the mammoth Mammuthus

E-1 NMBMMR OFR 454D imperator. The teeth of M. imperator are more New Mexico: Journal of Mammalogy, v. 61, p. advanced than M. meridonalis in having a higher 46-65. plate count, higher lamellar frequency, and thinner Hibbard, C. W., and Dalquest, W. W., 1966, Fossils enamel. The M. imperator specimen was found about from the Seymour Formation of Knox and 12 m higher in the section than the remainder of the Baylor Counties, Texas, and their bearing on Tijeras Arroyo fauna, and thus is somewhat younger, the late Kansan climate of that region: although an Irvingtonian age is still likely (Lucas et Contributions from the Museum of al., 1993). Paleontology, University of Michgian, v. 21, The presence of mammoths in unit 6 of Lucas et n. 1, 66 p. al. (1993) and above clearly establishes an Izett, G. A. and Obradovich, J. D, 1994, 40Ar/39Ar age Irvingtonian age for the upper part of the Tijeras constraints for the Jaramillo Normal Subchron Arroyo section, as Mammuthus is one of the defining and the Matuyama-Brunhes geomagnetic genera of the Irvingtonian NALMA. The first boundary: Journal of Geophysical Research, v. appearance of Mammuthus in the New World 99 (B2), p. 2925-2934. occurred sometime in the early Pleistocene (early Knight, P. J., Lucas, S. G., and Cully, A., 1996, Early Irvingtonian) between about 1.8 and 1.6 Ma. The Pleistocene (Irvingtonian) plants from the mammoth jaws from Tijeras Arroyo represent one of Albuquerque area, New Mexico: the oldest well-documented records of Mammuthus Southwestern Naturalist, v. 41, p. 207-217. from North America, based on an Ar/Ar age of 1.61 Lindsay, E. H., Opdyke, N. D., and Johnson, N. M., Ma on Guaje Pumice from the Sierra Ladrones 1984, Blancan-Hemphillian Land Mammal Formation in Tijeras Arroyo (Lucas et al., 1993; Izett Ages and late Cenozoic mammal dispersal and Obradovich, 1994; Lucas, 1995, 1996). Although events: Annual Review of Earth and the pumice date provides a maximum age for this Planetary Sciences, v. 12, p. 445-488. site, evidence from other pumice deposits of exactly Lucas, S. G., 1995, The Thornton Beach mammoth the same age farther south in the Rio Grande Valley and the antiquity of Mammuthus in North (Mack et al., 1996, 1998) indicates that the pumice is America: Quaternary Research, v. 43, p. very close in age to the fossils. The association of M. 263-264. meridionalis with Glyptotherium arizonae and Equus Lucas, S. G., 1996, The Thornton Beach mammoth: scotti is indicative of an early Irvingtonian age for the Consistency of numerical age and Tijeras Arroyo fauna. Correlative early Irvingtonian morphology: Quaternary Research, v. 45, p. faunas include the Tortugas Mountain LF (Lucas et 332-333. al., 1999, 2000) and Mesilla Basin Fauna C Lucas, S. G., and Effinger, J. E., 1991, Mammuthus (Vanderhill, 1986) from the Mesilla basin in southern from Lincoln County and a review of the New Mexico, Gilliland in Texas (Hibbard and mammoths from the Pleistocene of New Dalquest, 1966), and Holloman in Oklahoma Mexico: New Mexico Geological Society (Dalquest, 1977). Guidebook 42, p. 277-282. Lucas, S. G., Morgan, G. S. and Estep, J. W., 2000, REFERENCES Biochronological significance of the co- occurrence of the proboscideans Cuvieronius, Connell, S. D. and Hawley, J. W., 1998, Geology of Stegomastodon, and Mammuthus in the lower the Albuquerque West 7.5-minute quadrangle, Pleistocene of southern New Mexico: New Bernalillo County, New Mexico: New Mexico Mexico Museum of Natural History and Bureau of Mines and Mineral Resources, Open Science, Bulletin 16, p. 209-216. File Digital Map 17, Scale 1:24,000. Lucas, S. G., Williamson, T. E., and Sobus, J., 1993, Connell, S. D., Koning, D. J., and Cather, S. M., Plio-Pleistocene stratigraphy, paleoecology, 1999, Revisions to the stratigraphic and mammalian biochronology, Tijeras nomenclature of the Santa Fe Group. Arroyo, Albuquerque area, New Mexico: northwestern Albuquerque basin, New New Mexico Geology, v. 15, p. 1-8, 15. Mexico: New Mexico Geological Society, Lucas, S. G., Morgan, G. S. Estep, J. W. Mack, G. Guidebook 50, p. 337-353. H., and Hawley, J. W., 1999, Co-occurrence of Dalquest, W. W., 1977, Mammals of the Holloman the proboscideans Cuvieronius, Stegomastodon, local fauna, Pleistocene of Oklahoma: and Mammuthus in the lower Pleistocene of Southwestern Naturalist, v. 22, p. 255-268. southern New Mexico: Journal of Vertebrate Gillette, D. D. and Ray, C. E., 1981, Glyptodonts of Paleontology, v. 19, p. 595-597. North America: Smithsonian Contributions Mack, G. H., McIntosh, W. C., Leeder, M. R., and to Paleobiology, number 40, 255 p. Monger, H. C., 1996, Plio-Pleistocene Harris, A. H. and Porter, L. S. W., 1980, Late pumice floods in the ancestral Rio Grande, Pleistocene horses of Dry Cave, Eddy County, southern Rio Grande rift, USA: Sedimentary Geology, v. 103, p. 1-8.

E-2 NMBMMR OFR 454D

Figure 1. Stratigraphic column of Sierra Ladrones and Arroyo Ojito Formation strata at mouth of Tijeras Arroyo.

E-3 NMBMMR OFR 454D

Mack, G. H., Salyards, S. L., McIntosh, W. C., and Morgan, G. S., Lucas, S. G., and Estep, J. W., 1998, Leeder, M. R., 1998, Reversal Pliocene (Blancan) vertebrate fossils from magnetostratigraphy and radioisotopic the Camp Rice Formation near Tonuco geochronology of the Plio-Pleistocene Camp Mountain, Doña Ana County, southern New Rice and Palomas Formations, southern Rio Mexico: New Mexico Geological Society Grande rift: New Mexico Geological Guidebook, 49th Field Conference, p. 237- Society, Guidebook 49, p. 229-236. 249. Morgan, G. S. and Lucas, S. G., 2000, Pliocene and Tedford, R. H., 1981, Mammalian biochronology of Pleistocene vertebrate faunas from the the late Cenozoic basins of New Mexico: Albuquerque basin, New Mexico: New Geological Society of American Bulletin, Mexico Museum of Natural History and Part I, v. 92, p. 1008-1022. Science, Bulletin 16, p. 217-240. Vanderhill, J. B., 1986, Lithostratigraphy, vertebrate paleontology, and magnetostratigraphy of Plio-Pleistocene sediments in the Mesilla basin, New Mexico [PhD Dissertation]: Austin, University of Texas, 305 p.

E-4 NMBGMR OFR454D Reprinted with permission from New Mexico Bureau of Mines and Mineral Resources Bulletin 137, p. 162-163 (1991)

CUSPATE-LOBATE FOLDS ALONG A SEDIMENTARY CONTACT, LOS LUNAS VOLCANO, NEW MEXICO

William C. Haneberg1 New Mexico Bureau of Mines and Mineral Resources, 801 Leroy Place, Socorro, NM 87801

BACKGROUND OBSERVATIONS

Cuspate-lobate folds are characteristic of A series of exceptionally well developed strongly compressed interfaces separating media of cuspate-lobate folds is exposed along a sedimentary differing mechanical competence, with the lobate contact at los Lunas volcano (Fig. 1). Below the folds cored by the more competent material and the contact is a buff to orange alluvium composed of silt cuspate folds cored by the less competent material and fine sand, with no distinct bedding. Above the (e.g. Ramsay and Huber, 1987, p. 403). Other contact are a 1-2 cm thick white ash, a 10-15 cm commonly used terms for this type of feature include thick gray tephra ranging in size from sand to mullion, fold mullion, and arc-and-cusp structure. granule, and a coarser orange [sic] tephra up to 1 m Although cuspate-lobate folds are commonly thick. Much of the less-resistant alluvium beneath the associated with high-grade metamorphic rocks, their contact has been removed by erosion, showing that morphology is similar to that of alternating load casts both cusps and lobes extend at least a meter back into and flame structures in sedimentary sequences. In the outcrop; therefore, these folds can be analyzed as addition to having geologic significance as indicators two-dimensional structures. Most cusps in the of both competence contrast and shortening direction, sequence point downward, suggesting that the finer- cuspate-lobate folds are also amenable to theoretical grained alluvium was generally the more competent and experimental analysis. material during deformation; however, a few very Ramsay and Huber (1987, pp. 392-393) maintain low-amplitude cusps do point upward. The lobe that cuspate-lobate folds form only along interfaces portions of folds are somwhat flat, similar to a separating media of low viscosity contrast, perhaps theoretical pattern consisting of a positive first less than an order of magnitude. Smith (1975, 1977) waveform and a negative second waveform (Johnson and Fletcher (1982) analyzed the growth of and Pfaff, 1989, p. 128). Cusp amplitude and instabilities along interfaces separating both linear peakedness both decrease along the ash and tephra and nonlinear fluids, and concluded that, although so- contacts above the alluvium. In addition to the called mullion instabilities have small growth rates, prominent cuspate-lobate folds, the interface is also mullion growth is enhanced in nonlinear fluids. One folded into a gentle syncline with a wavelength on important conclusion of such analyses is that no first- the order of 102 m, and cut by two small thrust faults order dynamic instability, which would maximize the with shortening of 0.19 and 0.48 m. The distribution growth of structures with a preferred wavelength, of 54 fold wavelengths, measured by stretching a tape will develop between two semi-infinite fluids. between adjacent cusps, has a fairly strong central Instead, there is only kinematic amplification of pre- tendency (Fig. 2), with an arithmetic mean of 1.78 m existing perturbations alng the interface. Johnson and and a standard deviation of 0.76 m. Pfaff (1989) provided a detailed geometric analysis of the waveforms necessary to produce different CONCLUSIONS forms of folds, including-cuspate-lobate folds, and showed how cuspate-lobate folds might evolve from The existence of both cuspate-lobate folds and sinusoidal folds in linear viscous multilayers small thrust faults shows that the sedimentary contact subjec1ted to shortening of 6-8 %. Recent described in this paper has been shortened experimental work with strain-softening silicon putty significantly, and cusp orientation shows that the models (Sokoutis, 1990) has shown that cuspate- alluvium was from one to ten times more competent lobate structures grow rapidly along a single interface than the volcaniclastic sediments during deformation. separating two semi-infinite fluids with low viscosity If mass was conserved during shortening, the contrast, but again with no preferred wavelength, thickness of the stratigraphic section must also have subjected to shortening greater than 10%. grown proportionally. Although measurements of arc-length are appropriate for preferred wavelength studies (Sherwin and Chapple, 1968), straight-line 1 now at Haneberg Geoscience, 4434 SE Land cusp-to-cusp measurements are much easier to collect Summit Court, Port Orchard, WA 98366 and provide a useful first approximation of F-1 NMBGMR OFR454D wavelength distribution. Because neither theory nor experiment predict the existence of a preferred wavelength for cuspate-lobate folds along a single interface, we are faced with two alternative explanations for our observation of somewhat uniform wavelength. First, the cuspate-lobate folds could represent the amplification of pre-existing perturbations along the interface, for example ripple marks. Second, it is possible that a preferred wavelength evolved because the sediments on one or both sides of the interface behaved as finite layers, for which dynamic instabilities will arise. Smith (1975) for example, suggests that many cuspate- lobate folds along single interfaces in the field are actually the erosional remnants of a finite layer with Figure 2. Histogram and sample statistics of cusp-to- cuspate-lobate folds along both interfaces. At present, cusp wavelengths of 54 cuspate-lobate folds meager knowledge of the depositonal and measured at Los Lunas volcano. deformational history of these sediments does not allow either of these explanations to be favored over ACKNOWLEDGMENTS the other. It is hoped, however, that detailed mapping and mechanical analysis will provide a better This work was supported by the New Mexico understanding of the exceptional structures at Los Bureau of Mines & Mineral Resources. David Love Lunas volcano. introduced me to a number of structural problems along the flanks of Los Lunas volcano, assisted with wavelength measurements, and, along with John Hawley, read drafts of this contribution.

REFERENCES

Fletcher, R. C., 1982, Analysis of the flow in layered fluids at small, but finite, amplitudes with application to mullion structures: Tectonophysics, v. 81, pp. 51-66. Johnson, A. M., and Pfaff, V. J., 1989, Parallel, similar and constrained folds; in Johnson, A. M., Burnham, C. W., Allen, C. R., and Muehlberger, W., (eds.), Richard H. Jahns Memorial Volume: Engineering Geology, v. 27, pp. 115-180. Ramsay, J. G., and Huber, M. I., 1987, The techniques of modern structural geology, Vol. 2: Folds and fractures: Academic Press, London, 700 pp. Sherwin, J., and Chapple, W. M., 1968, Wavelengths of single layer folds: a comparison between theory and Figure 1. Example of cuspate-lobate folds developed observation: Americal Journal of Science, v. 266, pp. along interface between fine-grained alluvium 167-179. (lower) and ash-tephra sequence (upper) at Los Lunas Smith, R. B., 1975, Unified theory of the onset of folding, volcano. Note changes in cusp amplitude and boudinage, and mullion structure: Geological Society peakedness along bedding surface in volcaniclastic of America, Bulletin, v. 86, pp. 1601-1609. Smith, R. B., 1977, Formation of folds, boudinage, and sediments. Hammer handle is approximately 33 cm mullions in non-Newtonian materials: Geological long. Society of America, Bulletin, v. 888, pp. 312-320. Sokoutis, D., 1990, Experimental mullions at single and double interfaces: Journal of Structural Geology, v. 12, pp. 365-373.

F-2 Simplified Preliminary Geologic Map of the Isleta Reservation and surrounding areas Handout for Friends of the Pleistocene Field Trip (October 12-14, 2001) o o 106 45' 106 30' EXPLANATION Qrn z Volcanic Center Qre MAT f Tp Qv S Qa Qae Qpm P Popotosa Fm fault; dashed lines To 40 alluvium and eolian 98 Ch5 Yg indicate covered by Qae Qay Qv Qre Ch6 Qrd alluvium Qa 25 P Pleistocene AB Atrisco-Barelas zone volcanics Qpmt Qpm Qpmt Qsa 40 Qay middle piedmont (t=Tijeras) Tv e n Well Qsp o Qpo Pliocene z lt Qay Yg u volcanics Qpo a P 0 5 km f older piedmont eastern limit of TA1 s Qpm D U ra Ti axial-fluvial deposits Qra ije Qrp T Miocene Los Padillas fm o Xm intrusives 107 F F G M Qpm Qra S Ku C Qa PL1 o To A 35 Arenal fm Ku To To B Cretaceous U D Qa Xm Qrd o Qrp Qay Ys c r To Mds Los Duranes Fm e Permo-Triassic u Qre To P Qr Qra Qa P o Qae UTsp Ri IBM Qsa F D Edith Fm To R Pennsylvanian Tv M SF4 Qrn To Qrn Tv MW1 Qay Qsp(?) Yg To 36T Qv U D To Is2 Lomatas Negras fm Tv Proterozoic Qae To1 Qr Qa Tv Qsp(?) granite To To Tv 28 Qpm Xm Rio Puerco alluvium Xm Tsp Qay Qae Qro Qrd Qpm Proterozoic To Qa P older Rio Puerco metamorphic Qs Qsp alluvium Qsp P S Qav Qv Qa Qay Qv H Qpm U W D Los Lunas volc. alluvium Qa P Qs P Qs Is1 D U Tv San Clemente graben unit Tv To

Qa Qsa Qsp(?) m Qsa

Qay F

D s e axial-fluvial n o S r Qae S H U d Qsp H E Qav a

Qrp C L

Qae

Tv e Yg a piedmont To r To To Qv d r e n i Tsp

Tp a S r older piedmont DL Tv G Qay Tp To o i To Ti Qro Qa 25 BL P R Qr f Arroyo Ojito Fm Tv M 35 o 45'

Preliminary draft compiled from Maldonado et al., 1999, and in review; Connell et al., 1998; Connell, unpubl.; Karlstrom et al., 1994)