DFS do not lie within valleys unless the system increase in grain size, sand:mud ratios, and chan- Abstracts is in an incised phase, (4) meanderbelts tend to be nel amalgamation, with a corresponding decrease more laterally mobile on the open DFS, forming in tidal influence and coals. The DFS concept may “simple” meanderbelts rather than “amalgam- explain common patterns (e.g., upsection changes ated” meanderbelts during aggradational phases in sand:mud, sandbody thickness, and architecture) on the DFS, (5) floodplain deposits on DFS are observed in Cretaceous rock record examples and New Mexico Geological Society often dominated by avulsion deposits, especially is valuable in reservoir modeling at the basin scale. spring meeting in distal portions of the DFS, (6) greater preser- vation of floodplain deposits appears to occur on The New Mexico Geological Society annual DFS dominated by braided streams than found in GEOCHRONOLOGIC HISTORY OF DEPOSI- spring meeting was held on April 27, 2012, at the braided streams of tributary systems, and (7) axial TION OF THE UPPER CRETACEOUS PIC- Macey Center, New Mexico Tech, Socorro. Fol- streams in a basin, if confined laterally, and riv- TURED CLIFFS SANDSTONE, FRUITLAND lowing are the abstracts from all sessions given ers that are incised into the DFS appear to be FORMATION, AND KIRTLAND FORMA- at that meeting. similar in character to tributary systems. We also TION, SAN JUAN BASIN, NEW MEXICO expect soil morphology to vary with position on AND COLORADO, J. E. Fassett, jimgeology@ DFS, with different soil types found in proximal, Keynote presentation p. 48 qwest.net, Independent Research Geologist, 552 medial, and distal locations as well as laterally Session 1—Evaluating How Continental Sedimentary Los Nidos Drive, Santa Fe, New Mexico 87501 away from the active channel belt. Additionally, Basins Fill: Development and Preservation of For about 25 m.y., the Western Interior Seaway cycles of incision and aggradation should develop bisected the North American continent, with- Sedimentary Successions p. 48 characteristic soil distributions. We believe that Session 2—Paleontology p. 49 drawing and disappearing from most of the area this alternative view to fluvial facies distributions during Late Cretaceous time. In the San Juan Session 3—Volcanics and Tectonics p. 50 can lead to advances in facies distribution predic- Session 4—Geochemistry, Geomorphology, and Basin area of New Mexico and Colorado, the final tion based on paleosol character and channel belt regression of the western shoreline of the seaway Geothermal p. 51 geometries on DFS. Session 5—Posters p. 52 was accompanied by deposition of the shoreface 40 39 Author and subject indices p. 59 Pictured Cliffs Sandstone. Precise Ar/ Ar ages SESSION 1—EVALUATING HOW CONTINENTAL for sanidine crystals from eight altered volcanic SEDIMENTARY BASINS FILL: DEVELOPMENT AND ash beds precisely dated this regression across the KEYNOTE San Juan Basin as beginning 76.28 Ma when the PRESERVATION OF SEDIMENTARY SUCCESSIONS shoreline was in the southwest part of the basin and ending 73.55 Ma when the shoreline left the THE DISTRIBUTIVE FLUVIAL SYSTEM (DFS) GEOMORPHIC CHARACTERIZATION OF northeast part of the basin. (These ages are cor- PARADIGM: RE-EVALUATING FLUVIAL THE GILBERT RIVER DISTRIBUTIVE FLU- rected from those reported in Fassett 2000, per FACIES MODELS BASED ON OBSERVA- VIAL SYSTEM (DFS) AND IMPLICATIONS Kuiper et al. 2008; these authors assigned an age TIONS FROM MODERN CONTINENTAL FOR CRETACEOUS COASTAL FLUVIAL of 66.95 Ma to the K-Pg boundary versus an age of SEDIMENTARY BASINS, G. S. Weissmann, SUCCESSIONS, K. C. McNamara, kelsey82@ 66.5 Ma that had been assigned earlier.) The Pic- Department of Earth and Planetary Sciences, unm.edu, and G. S. Weissmann, Department tured Cliffs regression across the basin covered a University of New Mexico, Albuquerque, of Earth and Planetary Sciences, University of distance of 145 km and took 2.73 m.y. The strati- New Mexico 87131; A. Hartley, Department New Mexico, Albuquerque, New Mexico 87131 graphic rise of the Pictured Cliffs across the basin was 384 m and thus the thickness of rock concur- of Geology and Petroleum Geology, School of The Gilbert River distributive fluvial system (DFS) Geosciences, University of Aberdeen, Aber- rently deposited was also 384 m. of Queensland, Australia, flanks the Gulf of Car- These precise geochronologic data make it pos- deen, AB24 3UE, United Kingdom; G. Nichols, pentaria, an epeiric sea that occupies a slowly sub- Department of Geology, Royal Holloway, Uni- sible to calculate the sedimentation and regression siding intracratonic basin. Approximately 13 km of rates during the retreat of the Pictured Cliffs shore- versity of London, Egham, Surrey, TW20 0EX, progradation has occurred over the last 6 ka, largely line across the San Juan Basin.The overall average United Kingdom; and L. Scuderi, Department due to high sedimentation rates, low regional slope, rate of sedimentation during that time, based on of Earth and Planetary Sciences, University of and a slight sea level fall. This system exhibits the rock thickness, was thus about 140 m/m.y., and New Mexico, Albuquerque, New Mexico 87131 same depositional patterns as purely continental the average rate of regression of the shoreline was When we think of fluvial systems and associated DFSs: (1) a radial channel pattern, (2) a down-DFS about 53 km/m.y. The decompacted 380-m rock soils and their preservation in the rock record, decrease in both channel and grain size (the lat- thickness is 702 m yielding a corrected sedimen- we typically draw upon our experiences with ter inferred), (3) a lack of lateral channel confine- tation rate of 257 m/m.y. These rates are aver- tributary rivers, which are the most common in ment, (4) a broad fan shape, and (5) a down-DFS ages, but because there are eight dated ash beds the world. Indeed, most facies models that we increase in floodplain/channel area. The coastal in this stratigraphic section, the rock thicknesses use to interpret the rock record have been devel- plain portion (influenced by sea level changes) is and time durations between these dated ashes can oped on tributary rivers that exist outside active characterized by: (a) a contact between DFS and each be used to determine the variable rates of sedimentary basins or, if the river system studied marginal-marine deposits, (b) channel incision, sediment accumulation and shoreline regression lies within a sedimentary basin, the models devel- confinement, and lateral movement, (c) increased during the 2.73 m.y. it took for the Pictured Cliffs oped typically do not place the studied reach into channel width due to tidal influence, (d) sedi- to regress across the basin. These data also make it the context of the basin. A review of more than 700 ment redistribution (spits, small-scale deltas), and possible to estimate the rate of tectonic subsidence and the creation of accommodation space during modern continental sedimentary basins around (e) evidence of shoreline progradation (wave-cut the PC regression; that is 114 m/m.y. the world showed that rivers in active sedimen- platforms and beach ridges). Other coastal DFSs tary basins are generally deposited either (1) as are present in passive-margin settings in Australia, distributive fluvial systems (DFS), variously India, and Africa. Few modern examples of DFS COMPLEX SEDIMENT PRESERVATION AND called megafans, fluvial fans, and even alluvial spanning the terrestrial to marine realm exist, as: REMOVAL IN THE NORTHERN AND CEN- fans in the literature, or (2) as tributary systems in (1) modern coastlines are presently flooded due to TRAL TULAROSA BASIN, NEW MEXICO, an axial position that parallel the basin trend or in high-amplitude Quaternary sea level fluctuations, an interfan area between the large megafans, with DUE TO DEFLATION, BASE LEVEL CHANG- (2) many rivers are incised into large valleys (Mis- the vast majority of sedimentation in the basin ES, DOWN-WIND ACCUMULATIONS, AND occurring on the DFS. In these continental sedi- sissippi River) or incised into pre-existing coastal RECYCLING, D. W. Love, [email protected], mentary basins, we have identified more than 400 DFS deposits (Canterbury Plains of New Zealand, B. D. Allen, and D. J. Koning, New Mexico Bureau fluvial megafans (> 30 km in length), with count- Texas Gulf coastal plain), and (3) anthropogenic of Geology and Mineral Resources, New Mexico less smaller DFS filling the basins. These observa- modification conceals surface expressions and hin- Institute of Mining and Technology, 801 Leroy tions have implications for the interpretation of ders natural channel behavior (Godhavari River of Place, Socorro, New Mexico 87801; R. G. Myers, ancient fluvial deposits and the soils that form on India). Geomorphic observations on these systems U.S. Army, IMWE-WSM-PW-E-ES, White Sands these deposits. Rivers on DFS differ from rivers ultimately lead to sedimentologic and stratigraphic Missile Range, New Mexico 88002 in degradational settings in many potentially predictions regarding coastal DFS deposits that On the floor of the Tularosa Basin, deflation significant ways, including (1) a radial pattern cross the fluvial-marine interface, such as the Cre- has repeatedly controlled local base levels and of channels away from an apex (or intersection taceous Williams Fork Formation of Colorado. A related eolian, playa, and alluvial geomorphic point) exists on DFS, (2) channel systems com- purely progradational succession should be char- features, with eolian sediment being an impor- monly decrease in width and discharge and acterized by basal shoreface strata cut into by tid- tant contributor to aggradation on eastern basin thus cross-sectional area distally, (3) rivers on ally influenced channels, and exhibit an upsection margins. Modern surface water transports fine

48 New Mexico Geology May 2012, Volume 34, Number 2 sediment and dissolved salts to the lowest parts a narrowing of the basin floor, with a particu- that of a large squirrel (414 grams for Phenacol- of the basin in deflated, non-integrated playas larly rapid advance at 13.5–11 Ma; (3) develop- emur praecox). Phenacolemur developed enlarged such as modern Lake Lucero (base elevation ment of a gravel-bearing ancestral Rio Chama incisors and a reduced dentition. Phenacolemur 1,183 m, 44 m below the drainage divide to the by 12 Ma; and (4) shifting of the axial river onto species superficially appear to have a strong south). Shallow ground water controls depths the northwest structural platform after 11 Ma, at similarity in their dental characteristics but of deflation, which in turn determine local base least episodically. The progradation of the east- with closer observation, it becomes clear there levels. Deflation basins scoured and partially ern alluvial slope is interpreted to be controlled is significant variation in tooth number, mor- filled episodically, so alluvial terraces are pre- by increased activity along the basin master fault phology, and dental wear between Phenacolemur served at several intermediate levels between (ESPFS) and slower subsidence in the CAG. Poor- species. These variations can be interpreted to the maximum level of basin fill and present ly constrained middle Miocene progradation also be adaptations for different diets and evidence streams. At one of these levels (locally ~ 17 m occurred for eastern alluvial slope deposits in the of evolutionary adaption to paleoenvironments. below the level of maximum fill; 2–11 m above San Luis Basin to the north, and streams of the Teeth are involved in food acquisition and their Salt Creek) an inactive gypsum-marsh deposit western alluvial slope carried coarser bedload at morphology reflects food acquisition strategy. covers > 50 km2. Radiocarbon ages of 10,900 to ~ 14 Ma. These observations imply a paleoclimatic Using SEM dental microwear analysis, along 10,300 yr bracket as much as 1.5 m of gypsum- influence for the rapid 13.5–11 Ma progradation, with dental morphology and statistical analysis, marsh deposition. At least two intermediate driven by increased discharge and stream com- I show distinctions between three of the closely levels of terrace-alluvium lie between the marsh petence. Increased precipitation, higher subsid- related species (P. jepseni, P. citatus, and P. prae- and the level of maximum basin fill. Three levels ence rates along the ESPFS, and emergence of the cox). These differences in dentition between of Holocene alluvium are inset below the marsh, nearby Jemez volcanic field perhaps facilitated Phenacolemur species reflect differences in diet, reflecting short-term aggradation between defla- integration and headward elaboration of streams and indicate paleoenvironmental/evolutionary tion episodes and erosion by Salt Creek. During draining the Colorado Plateau, forming a single adaptions in this early primate that permitted Holocene time, between the San Andres Moun- river roughly coincident with the location of the closely related (basal and derived) Phenacolemur tain front and Alkali Flat, alluvial-fan drainages modern Rio Chama. High throw rates on a fault species to live in the same areas of the San Juan that had been graded to the edge of Pleistocene west of the ESPFS at 11–8 Ma facilitated the shift Basin, New Mexico, and Bighorn Basin, Wyo- Lake Otero cut downward and planed laterally of the San Luis Basin-draining, axial river onto the ming, concurrently. following 20 m of base-level fall during lake-bed northwest structural platform. But another driver deflation. for this westward shift may be larger sediment A STUDY OF THE HOLOTYPE OF ALLOTRIO- Deflated sediment was transported primarily delivery from streams draining the eastern allu- CERAS FLOWER 1955, J. H. McDonnell, New to the northeast. Lunette dunes formed imme- vial slope compared to the western alluvial slope Mexico Museum of Natural History and Sci- diately downwind of many blowout areas; and axial river. ence, 1801 Mountain Road NW, Albuquerque, White Sands dune field accumulated beyond New Mexico 87104 Lake Lucero and Alkali Flat. Farther downwind, clay- to sand-sized gypsum episodically formed SESSION 2—PALEONTOLOGY Allotrioceras is an enigmatic fossil from the Middle broad sheets. An unknown (presumably large) Ordovician of the Champlain Valley named and component of clay to fine sand, including gyp- VERTEBRATE COPROLITES FROM THE described by Dr. Rousseau Flower (1955) and assigned to the cephalopod order Endocerida as sum, is (and was) carried eastward to the alluvial LOWER PERMIAN (LOWER WOLFCAM- type species for a new family, the Allotriocerati- fans and slopes of the Sacramento Mountains. PIAN) GALLINA WELL LOCALITY, JOYITA dae. Since that time no new study on this fossil is Holocene runoff has reworked components of HILLS, SOCORRO COUNTY, NEW MEXICO, known to have been made, prior to that here. that sediment back onto the alluvial fans. Most A. K. Cantrell, T. L. Suazo, J. A. Spielmann, and S. G. Lucas, New Mexico Museum of Natural A close examination of the holotype, and only late Quaternary sediment preservation is on the know specimen of Allotrioceras, P-42726 of the eastern and western alluvial fans, in the proxi- History and Science, 1801 Mountain Road NW, Albuquerque, New Mexico 87104 New Mexico Museum of Natural History and Sci- mal hanging walls of active normal faults, but ence indicates that it is not a cephalopod and that episodic deflation precludes long-term sediment Vertebrate coprolites are the most common trace its resemblance to the siphuncle of the Endocerida preservation in the basin center. fossils found at the Lower Permian (middle is strictly superficial. Wolfcampian) Gallina Well locality in Socorro Allotrioceras consists of a narrow tubular struc- County, New Mexico (NMMNH locality 4668). ture of which there is 76 mm and a separate COMPARISON OF MIOCENE TECTONISM Despite the relative abundance of coprolites asymmetrically bilateral terminus. The tubular AND PALEOCLIMATE WITH RIFT-BASIN at the locality, little attention has been paid to structure is referred to as the stem, the terminus SEDIMENTATION AND DRAINAGE POSI- the coprolite ichno-assemblage. This ichno- as the calyx. Narrow structures diverge at the TIONS, ESPAÑOLA BASIN, NEW MEXICO, assemblage includes the first occurrence of opposite end of the stem from that are not simply D. J. Koning, [email protected], New Mex- Dakyronocopros arroyoensis in New Mexico, the the remnants of some mostly eroded shell. While ico Bureau of Geology and Mineral Resources, earliest appearance of Alococopros triassicus and cephalopods, including their endosiphuncles, New Mexico Institute of Mining and Technology, occurrences of Heteropolacopros texaniensis and show a distinct bilateral symmetry with one side 801 Leroy Place, Socorro, New Mexico 87801; and amorphous coprolites. The age and faunal asso- the mirror image of the other, this is not found in S. D. Connell, New Mexico Bureau of Geology and ciations of Alococopros triassicus from the Gallina Allotrioceras where the two halves are distinctly Mineral Resources—Albuquerque Office, New Well locality refute earlier assertions that longi- different internally. Mexico Institute of Mining and Technology, Albu- tudinally striated coprolite forms were produced querque, New Mexico 87106 by stem archosauromorphs and are restricted to We summarize Miocene clastic deposition in the the Mesozoic and Cenozoic Eras. AETOSAURUS FROM THE UPPER TRIAS- Española Basin (EB) and examine how drainage SIC BULL CANYON FORMATION, QUAY systems may respond to tectonic and paleocli- COUNTY, NEW MEXICO, AND ITS BIO- matic controls. The EB is a half-graben tilted west ECOLOGY OF EARLY EOCENE SAN JUAN CHRONOLOGICAL SIGNIFICANCE, T. L. toward the Embudo–Santa Clara–Pajarito fault BASIN, NEW MEXICO, PHENACOLEMUR Suazo, A. K. Cantrell, S. G. Lucas, and J. A. Spiel- system (ESPFS). An arm of the EB, called the Caña- JEPSENI WITH PHENACOLEMUR CITATUS mann, New Mexico Museum of Natural History da Ancha graben (CAG), extends southeast away AND PHENACOLEMUR PRAECOX FROM and Science, 1801 Mountain Road NW, Albu- from the ESPFS. A faulted structural platform lies BIGHORN BASIN, WYOMING—A STUDY querque, New Mexico 87104 northwest of the ESPFS. Syn-rift deposits of the OF MICROWEAR AND DENTAL VARIA- Aetosaurus is an Upper Triassic genus of rela- Santa Fe Group are particularly well exposed in TION AS A PROXY FOR EOCENE CLIMATE tively small and inornate aetosaurs known from the EB, and we could readily map western allu- CHANGE, C. D. Pilbro, [email protected], three species: A. ferratus, A. crassicauda, and A. vial slope, central basin floor, and eastern alluvial Department of Earth and Planetary Sciences, arcuatus. A record of A. arcuatus from the Bull slope lithofacies assemblages. Abundant tephra University of New Mexico, Albuquerque, New Canyon Formation of the Chinle Group in east- and fossils provide exceptional age control. Pre- Mexico 87131 central New Mexico correlates these strata to vious studies documented an increase in ESPFS Phenacolemur was a widespread genus of Plesi- Aetosaurus-bearing strata in the eastern United throw rates at 15–11 Ma and decreased subsid- adapiforms (primate-like animals) that lived States, Italy, Greenland, and Germany. The genus ence rates in the CAG after 13.5–13.0 Ma. Paleo- from the late Paleocene to early Eocene of has been stated to be a reliable tetrapod index drainage changes included: (1) coarsening ca. North America and Europe. Members of this fossil for the Revueltian (Norian), making the 13.2 Ma; (2) progressive westward progradation genus were small, varying in size from that of specimens of A. arcuatus from the Bull Canyon of the eastern alluvial slope during 18–10 Ma and a mouse (121 grams for Phenacolemur jepseni) to Formation in Quay County, New Mexico, which

May 2012, Volume 34, Number 2 New Mexico Geology 49 are part of the characteristic Revueltian tetrapod reflecting variations in local spring chemistry and New LA-ICP-MS U-Pb ages on zircon crys- assemblage, important to Late Triassic tetrapod temperature. Compared to global travertine data, tals from airfall tuff beds within the Skunk biochronology. While many specimens have Soda Dam travertines have relatively positive C Ranch Formation, a Laramide synorogenic unit been collected from the Aetosaurus locality in isotope values of +1.4 to +11.7, suggesting degas- exposed in the Little Hatchet Mountains, south- the Bull Canyon Formation (NMMNH L-501), sing of CO2 in the hydrothermal system. western New Mexico, indicate a chronostrati- only the most diagnostic have been previously graphic age of 71–70 Ma. Ranging from 374 m reported. Here we describe additional aetosau- thick in its southern exposures to 738 m in rian material in the collection of the New Mexico CALCITE-FILLED FRACTURES IN TRAVER- northern exposures near Playas Peak, the Skunk Museum of Natural History from L-501, includ- TINE USED TO CONSTRAIN THE TIM- Ranch Formation is divided into three informal ing a partial skeleton, numerous paramedian ING AND ORIENTATION OF QUATERNA- members including a lower conglomerate mem- and lateral scutes, lateral appendage scutes, ver- RY EXTENSION ALONG THE WESTERN ber, a middle member of lacustrine shale and tebral fragments, and various limb and hip ele- MARGIN OF THE RIO GRANDE RIFT, basaltic-andesite flows, and an upper member of ments. After Typothorax, Aetosaurus is the second CENTRAL NEW MEXICO, J. W. Ricketts, A. conglomerate and sandstone. Near Playas Peak, most common aetosaur in the Bull Canyon For- Priewisch, M. Kolomaznik, and K. E. Karlstrom, the Skunk Ranch Formation overlies a thick sec- mation. The distribution of Aetosaurus in Chinle Department of Earth and Planetary Sciences, tion of the Campanian Ringbone Formation, but Group strata includes records in the Rock Point University of New Mexico, Albuquerque, New south of the Mojado thrust fault, the lower mem- Formation, well documented from the Eagle Mexico 87131 ber unconformably overlies Albian carbonate Basin of Colorado. These records indicate that Large-volume travertine deposits in the Lucero strata. The Mojado thrust cuts the lower member the Revueltian–Apachean boundary is not, as uplift provide an excellent opportunity to under- and terminates in a fault-tip anticline in the mid- previously assumed, coincident with the base of stand and quantify Quaternary extension along dle member, which thus provides a minimum the Rock Point lithosome, but instead is at least the western boundary of the Rio Grande rift. age on fault movement. Three tuff beds from the locally above its base. Vertical quarried faces expose travertine mounds middle member were dated and yielded strati- that have been subsequently cut by multiple sys- graphically consistent ages. The stratigraphically tems of extensional fractures. We focus on three lowest sample yielded a weighted mean age of SESSION 3—VOLCANICS AND TECTONICS quarry sites (Temple Cream, Scheherazade, and 71.4 ± 0.5 Ma (n = 81; MSWD = 0.89). The mid- Vista Grande), as well as a fourth location, Red dle tuff bed has a weighted age of 70.6 ± 0.7 Ma URANIUM-SERIES DATING OF TRAVER- Hill, in an attempt to understand the timing and (n = 32; MSWD = 0.39). The stratigraphically TINE FROM SODA DAM, NEW MEXICO: implications of fracture formation. highest tuff bed yielded a weighted mean age CONSTRUCTING A HISTORY OF DEPOSI- At each of the quarry sites, at least three frac- of 70.4 ± 0.5 Ma (n = 60; MSWD = 1.04). The new TION, WITH IMPLICATIONS FOR LAND- ture sets were observed and measured. Cross- ages indicate that the Skunk Ranch is Campan- SCAPE EVOLUTION, PALEOHYDROL- cutting relationships at Temple Cream and Sche- ian–Maastrichtian in age, rather than Eocene as OGY, AND PALEOCLIMATOLOGY, A. J. herazade indicate that a set of horizontal sills previously interpreted on the basis of ostracodes Tafoya, L. J. Crossey, K. E. Karlstrom, V. Polyak, Y. are younger than vertical ~NS–~NE-SW trend- and that it is correlative with the Hidalgo For- Asmerom, and C. Cox, Department of Earth and ing and ~EW–~NW-SE trending fractures. Vista mation, a thick section of andesitic flows and Planetary Sciences, University of New Mexico, Grande exposes a more complex history, where flow breccias. The Skunk Ranch Formation was Albuquerque, New Mexico 87131 vertical and horizontal fractures repeatedly formerly interpreted to record the second phase crosscut one another. Red Hill is a small mesa of a two-stage history of Laramide deformation High precision uranium-series geochronology of Permian sandstone and siltstone capped by at Soda Dam, New Mexico, provides a record of in southwestern New Mexico. In addition to sig- travertine. NE-SW trending extensional fractures nificantly improving stratigraphic correlation paleohydrology and incision history for the upper similar to those observed at the quarry sites cut reaches of the Jemez River over the last 700 ka. of Laramide strata, the new radiometric ages the Permian rocks and acted as conduits for fluid indicate that Laramide deformation in the Little Active travertine-depositing hot springs occur flow, feeding the overlying travertine deposit. In along the intersection of the Soda Dam fault, and Hatchet Mountains likely was restricted to the addition, small-scale (< 1 m) normal faults cut latest Cretaceous. the Jemez River; new dates on active and extinct the Permian rocks. Preliminary U-series dating deposits provide improved geochronologic and of the travertine mound at Scheherazade indi- geologic context with respect to the timing of trav- cates it was deposited ~ 750–650 ka. The exten- NOGAL CANYON CALDERA, SOUTHERN ertine accumulation. The largest volume-accumula- sional fractures and sills observed at each of the tion, Deposit A, yields ages ranging from > 700 ka four locations are thus younger than ~ 600 ka. SAN MATEO MOUNTAINS, SOCORRO to 259.6 ± 14.5 ka. The oldest ancestral Jemez River NS and NE-SW trending fractures observed at COUNTY, NEW MEXICO; A PROGRESS gravels are preserved beneath Deposit A, at a maxi- all study sites (as well as NE-trending normal REPORT, V. T. McLemore, [email protected], mum elevation of 132 m above the modern river; faults at Red Hill) indicate ~EW–NW-SE orient- New Mexico Bureau of Geology and Mineral efforts to date pumice clasts are ongoing, but model ed extension that, although of small magnitude, Resources, New Mexico Institute of Mining ages of ~ 700 ka provide an estimate of 188 m/Ma are compatible with Quaternary far field exten- and Technology, 801 Leroy Place, Socorro, New over the last 700 ka. This agrees with longer term sion related to continued development of the Rio Mexico 87801 bedrock incision rates of 200 m/Ma, from the base Grande rift. A prominent set of late horizontal sills The Nogal Canyon caldera is the southernmost of the 1.1 Ma Bandelier Tuff. Inset into Deposit A, overprints the subvertical faults and is not consis- caldera that formed the San Mateo Mountains. Deposit A1, contains travertine-coated Jemez River tent with this E-W extension. Instead, these reflect Mt. Withington (27.4 Ma) and Bear Trap Can- gravels with a strath 30 m above the modern river; subvertical least compressive stress and suggest yon (24.4 Ma) calderas are north of the Nogal these yield an age of 200.6 ± 2.1 ka, giving a bed- a regime of high fluid pressure that reduced Canyon caldera. Six peaks in the southern range rock incision rate of 150 m/Ma over the last 200 ka. the effective normal stress and caused rotation exceed 3,000 m in elevation: Vicks Peak (3,287 m), A crosscutting vein, at the same elevation as the of regional stress fields. This was likely due to San Mateo Mountain (3,092 m), San Mateo 200 ka sample, yields an age of 110.9 ± 1.5 ka, sug- upward movement of deeply sourced CO2-rich Peak (3,090 m), West Blue Mountain (3,287 m), gesting substantial artesian head during the 5e sub- fluids to the surface from Socorro Magma Body- stage of the Eemian interglacial. Deposit B, at lower Blue Mountain (3,142 m), and Apache Kid Peak like chambers. We conclude that Quaternary far (3,063 m) and are remnants of the resurgent Nogal elevations, developed on a banded central fissure field extension is ongoing, and stress fields are Canyon caldera. The Vicks Peak Tuff (28.4 Ma), ridge; combined ages from the fissure and mound modified in the region of the Socorro Magma granite intrusions, and associated rhyolite and accumulation indicate the system was active from Body by ascending CO2-rich fluids. 138–78 ka, a 60,000 yr interval spanning the transi- quartz latite flows and domes erupted from this tional period during termination II. Deposit C, at caldera. The Vicks Peak Tuff is > 490 m thick and 23 and 16.5 m above the modern river, respectively, LATE CRETACEOUS U-Pb TUFF AGES FROM is overlain by > 550 m of rhyolite (Lynch 2003). yielded ages of 103.2 ± 0.5 ka and 101.7 ± 0.5 ka, THE LARAMIDE SKUNK RANCH FORMA- The estimated diameter of the caldera is 25 km, giving a river incision rate of 160 m/Ma over the TION, LITTLE HATCHET MOUNTAINS, and Lynch (2003) estimated the total volume of last 100 ka. Our results suggest semi-steady bed- SOUTHWESTERN NEW MEXICO, G. R. Jen- the Vicks Peak Tuff as 1,816 km3. Re-interpretation rock river incision since ~ 1 Ma with episodic trav- nings, and T. F. Lawton, Department of Geologi- of past studies and recent mapping by this author ertine deposition along the Soda Dam fault system cal Sciences, New Mexico State University, Las in the southern San Mateo Mountains has refined at 400–700 ka, 260–360 ka, 134–96 ka, and < 5 ka; Cruces, New Mexico 88003; C. A. Clinkscales, the history of the caldera. Some of the northern reflecting the changes in climate, regional volcanic Department of Geological Sciences, New Mex- parts of the caldera remain unmapped. processes, and the existence of the Valles caldera ico State University, Las Cruces, New Mexico Stratigraphic relationships indicate that the paleolakes. Stable isotope values of the dated trav- 88003 and ConocoPhillips Company, Houston, eruption of the Vicks Peak Tuff was followed by ertines range from δ180 = −19 to −6.5 per mil (PDB), Texas 77079 intrusion of the granite of Kelley Canyon and

50 New Mexico Geology May 2012, Volume 34, Number 2 rhyolite of Alamosa Canyon, within < 0.42 Ma The Burro Mountains of New Mexico lie at the west and the very thick (up to 1,000 m) Panther (Lynch 2003) in the western part of the caldera. southernmost edge of the Mogollon–Datil volca- Seep Formation (Missourian–early Wolfcampian) Geochemical studies confirm they were from the nic field. New U-Pb zircon ages from intermedi- to the east. This lithosome is mixed clastic and car- same source. The Springtime Canyon Formation ate and felsic lava flows, hypabyssal intrusions, bonate strata within which the Bursum base has overlies the Vicks Peak Tuff and consists of rhyo- and ash-flow tuffs provide new age constraints a demonstrably disconformable contact on older lite, quartz latite and latite flows, and associated on timing of magmatism in the Burro Mountains. strata. A comprehensive analysis of lithostratig- tuffs erupted along the eastern boundary, proba- The youngest andesite lava flow was analyzed raphy, facies, and biostratigraphy allows us to bly during this time period, but dating is required. for Sr-isotope compositions to determine degree construct a tectonostratigraphy of the Pennsylva- Rhyolite dikes and small rhyolite domes erupted of and source of contamination by country rock. nian strata in Sierra County that identifies three along the southern and northern boundaries and U-Pb LA-MC-ICPMS and SHRIMP zircon ages pulses of the ancestral Rocky Mountain (ARM) could be related to the caldera. The northern of volcanic rocks in the Saddlerock area of the orogeny: (1) onset of the ARM at about the end boundary of the caldera is partially concealed by Burro Mountains indicate a compositional tran- of Morrowan time with initial synorogenic Red the formation of the Mt. Withington caldera and sition at ~ 34 Ma from intermediate stratocone House clastics deposited unconformably on older eruption of the Vicks Peak Tuff and younger rhyo- magmatism to felsic magmatism of the School- Paleozoic strata; (2) a pulse close to the beginning lites. However, San Juan Peak is along the north- house Mountain caldera. Weighted mean ages of the Missourian, indicated by basal Missourian eastern boundary, where an undated peralkaline for Saddle Rock Canyon Formation andesite conglomerates and/or the relatively thin (locally rhyolite flow and dikes overlies Vicks Peak Tuff, lava flows ranged from 33.5 to 35.3 Ma. Andes- absent) Missourian section; and (3) a latest Penn- and probably is one of the last eruptions associ- ite breccias interfingered with the first overlying sylvanian pulse indicated by the sub-Bursum ated with the caldera. The caldera was offset local- rhyolite ash-flow tuff and tuff-breccia of the Kerr unconformity. Although eustasy can be invoked ly by younger Basin and Range faults (i.e., Rock Canyon Formation, which yielded an age of 34.3 to explain some of the stratigraphic architecture of Springs–Priest, Indian Peaks, Rhyolite, Dark Can- ± 0.4 Ma. The Kerr Canyon latite yielded an age the Pennsylvanian System in Sierra County, much yon, Bell Mountain faults). The San Jose mining of 34 ± 0.98 Ma, and flow-banded rhyolite plug, more of it is explicable by ARM tectonism, par- district (Au, Ag, Cu) lies within the caldera along which intruded the latite, an age of 34.7 ± 1.6 Ma. ticularly by a local Caballo uplift (centered near these Basin and Range faults, and associated A rhyolite dike, which crosscut an andesite dike the Derry Hills?) present and tectonically active hydrothermal alteration has made stratigraphic (33.5 ± 0.3 Ma), yielded an age of 33.7 ± 0.4 Ma. intermittently during the Pennsylvanian. correlations difficult. Another dike, mapped previously as an Oligo- cene rhyolite, yielded a weighted mean age of 75 ± 1.3 Ma. Current mapping and geochronology SESSION 4—GEOCHEMISTRY, GEOMORPHOLOGY, IDENTIFYING THE MAGMA SOURCE(S) OF suggest that ~ 75 Ma magmatism in the Burro AND GEOTHERMAL THE CARRIZOZO LAVA FLOW, SOUTH-CEN- Mountains was more extensive than previously TRAL NEW MEXICO, E. Gladish, sumatra@nmsu. determined and provided moderate xenocrys- HOW TREES INTERACT WITH THEIR ENVI- edu, F. C. Ramos, and N. J. McMillan, Depart- tic zircon contamination in Paleogene volcanic RONMENT: A STABLE ISOTOPE STUDY, ment of Geological Sciences, New Mexico State rocks. C. G. Gierek, [email protected], Department of University, Las Cruces, New Mexico 88003; M. Single-crystal TIMS analysis of seven plagio- Earth and Environmental Science, New Mexico C. Rowe, School of Earth and Environmental Sci- clase crystals from the youngest Mangas Creek Institute of Mining and Technology, 801 Leroy 87 86 ences, Washington State University, Pullman, andesite lava flow have ( Sr/ Sr)o values from Place, Socorro, New Mexico 87801; and B. T. Washington 99164 0.7074 to 0.7079 when age-corrected to a U-Pb Newton, New Mexico Bureau of Geology and The Carrizozo lava flow, located in south-central LA-MC-ICPMS zircon age of 33.8 ± 0.7 Ma. Erup- Mineral Resources, New Mexico Institute of New Mexico, is a young (~ 5,000 ka) tholeiitic tion of the andesite lava through thick intracal- Mining and Technology, 801 Leroy Place, Socor- basalt flow erupted in the Rio Grande rift, which dera deposits and lack of assimilation of Protero- ro, New Mexico 87801 zoic basement rock can explain the (87Sr/86Sr) consists of separate upper and lower flows. Whole o The Sacramento Mountain Watershed Study is signatures observed. rock data for six lobes of the lower flow and three designed to assess the effects of tree thinning in lobes of the upper flow indicate a minimal role for mountain watersheds as an effective method of fractional crystallization within the flows. Melt- increasing ground water recharge. The project ing of heterogeneous mantle sources or magma PENNSYLVANIAN STRATA AND ANCES- employs a soil water balance to quantify the par- mixing/assimilation can account for variations of TRAL ROCKY MOUNTAIN TECTONISM titioning of local precipitation before and after major and trace elements and 87Sr/86Sr ratios of IN SIERRA COUNTY, NEW MEXICO, S. G. tree thinning. We are using the stable isotopes whole rocks. Six lobes of the lower flow encom- Lucas, New Mexico Museum of Natural His- pass ~ 2% SiO variation and < 1% MgO variation of oxygen and hydrogen to identify tree water 2 tory, 1801 Mountain Road NW, Albuquerque, sources. The study is being conducted in a first and slight K2O and Al2O3 variations, which sug- New Mexico 87104; K. Krainer, Institute of gest little, if any, olivine or plagioclase fraction- order watershed with no perennial outflow Geology and Paleontology, Innsbruck Uni- stream where vegetation is dominated by Doug- ation. ~ 1% magnetite fractionation can account versity, Innrain 62, Innsbruck A-6020, Austria; for decreasing Fe O contents but cannot account las-fir (Pseudotsuga Menziesii). Ridges are capped 2 3 W. J. Nelson, Illinois State Geological Survey, for a 2% increase in SiO . These lobes define a lin- with San Andres Limestone, whereas lower 2 615 East Peabody Drive, Champaign, Illinois ear trend in 87Sr/86Sr–1/Sr indicating two compo- slopes and the valley bottom are underlain by 61820; and J. A. Spielmann, New Mexico Muse- nent mixing of which one component has higher the Yeso Formation. From March to November um of Natural History, 1801 Mountain Road Sr and lower 87Sr/86Sr ratios and the other, lower 2011, we collected several soil and twig samples Sr and higher 87Sr/86Sr ratios. Additionally, both NW, Albuquerque, New Mexico 87104 from which water was extracted by cryogenic Sr and Zr increase with decreasing SiO2, which is Pennsylvanian strata are well exposed in the San vacuum distillation. Mobile soil water was sam- inconsistent with fractionation. Andres, Fra Cristobal, Caballo, and Mud Springs pled with passive capillary samplers (PCAPS) For the three lobes of the upper flow, 87Sr/86Sr–1/ Mountains in Sierra County, New Mexico. The placed in soil profiles. Sr does not define a linear correlation, thus mix- oldest of these strata are the Morrowan–Atokan The isotopic composition of bulk soil water ing may not have occurred. However, 3.5% olivine Red House Formation, a mixed siliciclastic-car- appears to be controlled by evaporation of snow- fractionation can account for observed decreasing bonate unit (shale, sandstone, and limestone) as melt stored within the soil matrix. The isotopic MgO contents, although K2O and Na2O contents much as 50 m thick. The overlying Pennsylva- composition of mobile soil water is a result of are lower than expected while Fe2O3, TiO2 and nian lithosome is dominated by cyclically bedded mixing of non-evaporated rainfall and evapo- SiO2 are higher than expected. Assimilation of a cherty limestone, nodular limestone, and shale, rated bulk soil water. As the monsoon season mafic source, occurring during fractionation, could the Atokan–Desmoinesian Gray Mesa Formation progressed and cumulative rainfall increased, account for variations in these major elements. (Nakaye Formation and Lead Camp Limestone the isotopic composition of mobile soil water are unnecessary synonyms) as much as 388 m evolved toward that of local precipitation. The thick. Member-level subdivisions of the Gray isotopic composition of twig water samples from U-Pb ZIRCON AND SR-ISOTOPE CON- Mesa Formation—Elephant Butte, Whiskey Can- March and July resembled that of bulk soil water. STRAINTS ON AGE AND CONTAMINA- yon, and Garcia members—can be recognized in In August and September, twig water isotope TION OF PALEOGENE VOLCANIC ROCKS some sections, but not in others, due to substan- values appeared to have both bulk soil water and OF THE BURRO MOUNTAINS, SOUTH- tial lateral facies changes. The youngest Pennsyl- mobile soil water contributions. WEST NEW MEXICO, T. N. Jonell, tjonell@ vanian lithosome is more regionally complex, and The conceptual model that we have developed nmsu.edu, J. M. Amato, and F. C. Ramos, Depart- is the relatively thin (up to ~ 63 m at Bar-B Draw) to explain this phenomenon relies on differences ment of Geological Sciences, New Mexico State Bar-B (Missourian–Virgilian) and (up to 120 m) in how snowmelt and monsoon precipitation University, Las Cruces, New Mexico 88003 Bursum (lower Wolfcampian) formations to the enter the subsurface, which determines where

May 2012, Volume 34, Number 2 New Mexico Geology 51 each water source is stored. Snowmelt infiltrates by an Oligocene laccolith. Two low-temperature are noisy. WT logs measured in air drilled holes soil and is stored in the matrix, whereas water warm springs, Ojo Caliente and Chise, indicate and filled with formation water before measure- from short duration, intense rainstorms prefer- that hot water may be present at depth. ment yield thermal data of a quality similar to entially flows through macropores and quickly Geothermal gradients from wells range from equilibrium logs. flushes through soil profiles to shallow epikarst 20°C/km to 60°C/km, with higher gradients locat- Temperatures of 150°C at depths of ~ 3 km are features in the underlying bedrock. In the spring ed on the eastern side of the SC horst, coincident present in the Colorado part of the Raton just north and early summer, trees use soil water. During with both warm springs. The Chise warm spring of the border. ET data from the Stubblefield Can- monsoon season when epikarst storage increas- occurs at the intersection of the eastern boundary yon area just south of the state line yield published es, a secondary root system is able to begin fault of the SC and a northeast-striking accommo- heat flow values of 89–120 mW/m2. If the elevated exploiting this newly available source. The con- dation zone called the Chise lineament. Gravity gradients derived from ET, BHT, and WT data from tribution of this secondary source manifests in highs and magnetic anomalies coincide with the Stubblefield Canyon are extrapolated to depth, then tree water as an integrated mixture of bulk soil Morenci and Chise volcanic lineaments along the a temperature of 150°C is reached at 3 km, compa- water and epikarst water. northern and southern ends of the graben. rable to the depths on the Colorado side of the bor- Water chemistry data from recharge (BR) and der. The difference in temperature between the SRB discharge areas (Chise warm spring) show a trend and the LVB is attributed to (1) elevated heat flow of calcium to sodium and carbonate to chloride- associated with low velocity mantle beneath the RECONSTRUCTING QUATERNARY PLU- dominated waters. Water table data suggest both SRB, and (2) erosion of low thermal conductivity VIAL EPISODES USING TRAVERTINES along axis and cross axis flow direction within the Cretaceous shales from the LVB. OF EGYPT'S WESTERN DESERT, G. Jimenez, basin. This chemical trend may be the result of [email protected], L. J. Crossey, K. E. Karl- ion exchange along a deep, long-lived west to east strom, J. W. Ricketts, and A. J. Tafoya, Depart- flowpath. Carbon 14 dating at Ojo Caliente yield- SESSION 5—POSTER SESSION ment of Earth and Planetary Sciences, Uni- ed ground water ages in excess of 13 ka. Mineral versity of New Mexico, Albuquerque, New solubility simulations (carbonate and silicate) PRELIMINARY RESULTS FROM A LATE PLEIS- Mexico 87131; T. Anan, and A. Mohammed, indicate that chemistry from the Chise and Ojo TOCENE TO HOLOCENE PALEOCLIMATE Department of Geosciences, Western Michigan Caliente warm springs were in thermal equilib- STUDY OF THE LAKE SEDIMENT CORES, University, Kalamazoo, Michigan 49008 rium at temperatures between 70 and 100°C. NORTHERN NEW MEXICO, A. R. Brister, abris- Quaternary climate in North Africa was marked Because the temperature anomalies trend east- [email protected], and M. S. Petronis, Environ- by multiple pluvial periods overprinting west and water table gradients trend both east-west mental Geology Program, Natural Resource Man- extreme aridity, but pluvial drivers, as well as and north-south, a two component hydrogeologic agement Department, New Mexico Highlands their timing and geographic extent, are poorly system is proposed. The deeper system consists University, Las Vegas, New Mexico 87701 of ground water flowing from the BR eastward constrained. We address these factors in the The geography of the Las Vegas National Wild- first comprehensive analysis of travertine from below the WG, where the water is heated by high background heat flow. The warm water continues life Refuge (LVNWR) and surrounding region Egypt’s Western Desert, which represents a has changed dramatically since the late Pleisto- unique and under-utilized sedimentary record of to flow eastward through the SC, emerging within and to the east of the horst. cene in response to the expansion and contraction paleoclimate and paleohydrology. We focus on of alpine glaciers activity and associated climate correlating travertine deposition either to glacial change. During the late Pleistocene, we hypoth- cycles or to more specific orbital forcings, par- GEOTHERMAL POTENTIAL OF THE SOUTH- esize that the area just east of the Sangre de Cristo ticularly precession, acting on the North African ERN RATON BASIN, NEW MEXICO, S. A. Mountains at the latitude of Las Vegas, New Mex- summer monsoon. An age-probability plot of Kelley, and R. Broadhead, New Mexico Bureau of ico, consisted of several or a network of intercon- published U-series ages shows no obvious corre- Geology and Mineral Resources, New Mexico nected lacustrine systems. Following the end of lation between travertine occurrence and glacial Institute of Mining and Technology, 801 Leroy glacial activity, these lacustrine systems shrank to cycles (the dominant literature conclusion), so Place, Socorro, New Mexico 87801; R. E. Salaz, their current condition of minor low-volume iso- that forcings remain enigmatic. Following previ- and M. Tewelde, Department of Earth and Envi- lated lakes and numerous playas and pluvial bod- ous workers, we assume that large-scale traver- ronmental Science, New Mexico Institute of ies. Preliminary data from an integrated, paleocli- tine accumulations reflect pluvial episodes, via Mining and Technology, 801 Leroy Place, Socor- matic study of sediment cores collected from three raised ground water head supplying adequate ro, New Mexico 87801 playa lakes provide insight into late Pleistocene to water for travertine precipitation from CO2-rich Holocene paleoclimatic variations in northeastern oasis springs. We collected ~ 60 additional geo- The geothermal potential of the southern Raton Basin (SRB) is evaluated using equilibrium (ET), New Mexico. Sedimentologic, midge fossil, and logically and volumetrically well-constrained rock magnetic data acquired from the sediment samples in January 2012, sampling deposit tops bottom hole (BHT), and wireline (WT) tempera- ture data. ET logs are generally from shallow cores is used to characterize the materials, identify and bottoms to resolve inception and termina- stratigraphic changes, document shifting lake lev- tion of pluvials as well as regional aggradation/ wells (< 600 m); interval geothermal gradients generally correspond to lithology, which is indica- els, assess temperature changes, and infer paleo- incision patterns, and also banded feeder vein climate conditions. Data collected from McAllis- systems to establish finer-scale wet/dry fluctua- tive of conductive heat flow. Interval geothermal gradients in the Paleogene Raton and Poison Can- ter and Wallace Lake are encouraging and reveal tions. Our goal is to contribute to an understand- depth dependent changes in fossil assemblages, ing of low-latitude climate and monsoon dynam- yon formations and in Cretaceous shales (Pierre, grain size, and rock magnetic properties that have ics, as well as Western Desert hydrology, with Carlile, Graneros) are on the order of 40–60°C/ been interpreted to reflect climatic driven varia- implications for modern water management. km. In contrast, interval gradients in the Creta- ceous Trinidad Sandstone and in other sandy tions impacting the depositional system. Bulk units are 20–30°C/km. low-field magnetic susceptibility decreases by an BHT data constrain the deeper thermal struc- order of magnitude from the surface to the base of GEOTHERMAL EXPLORATION OF THE WIN- ture of the basin. High BHTs were measured in the measured core suggesting a change in detri- STON GRABEN, CENTRAL NEW MEXICO, the Stubblefield Canyon gas field near the Colo- tal magnetic influx into the lacustrian system. USA, M. J. Sophy, [email protected], Depart- rado border; the maximum uncorrected BHT is Curie point estimates indicate that the dominant ment of Earth and Environmental Science, New 135°C at a depth of 2,160 m and associated geo- magnetic mineral in all samples is cubic, low-Ti Mexico Institute of Mining and Technology, 801 thermal gradients are 50–80°C/km. BHTs in the titanomagnetite phase. An environmental mag- Leroy Place, Socorro, New Mexico 87801; and Las Vegas Basin (LVB) to the south are cooler netism study of sediment from the LVNWR and S. A. Kelley, New Mexico Bureau of Geology (85°C at 3,091 m) compared to those in the SRB surrounding playas can help provide an invalu- and Mineral Resources, New Mexico Institute to the north at similar depths. This study focuses able and untapped record of late Pleistocene to of Mining and Technology, 801 Leroy Place, on wells with two or more BHT readings. Four Holocene climatic change. Additional data are Socorro, New Mexico 87801 wells with multiple BHTs in the Castle Rock Park being collected that will aid with interpreting the The geothermal potential of the Winston graben gas field show a distinct decrease in temperature evolution of the lacustrine system. We postulate (WG) is evaluated using well temperature logs, between measurements in the Trinidad Sandstone that concurrent with alpine glacial activity dur- gravity and magnetic data, water chemistry, and and measurements in the underlying Pierre Shale. ing the Pleistocene, the LVNWR and the transi- water table measurements. The WG is a late This pattern implies lateral flow of warm (~ 45°C) tional Great Plains region to the northeast were Cenozoic rift basin, part of the Rio Grande rift, water in the Trinidad Sandstone in this area. an expansive single lake or interconnected lake which is bordered by the Black Range (BR) to the WT logs can provide good thermal data if used system, analogous to the Pleistocene lakes of the west and is separated from the Rio Grande valley with caution. WT logs are obtained by oil compa- Estancia Basin (Lake Estancia) and the Tularosa by the Sierra Cuchillo (SC), a horst block com- nies to look for zones of fluid flow or to gauge the Basin (Lake Otero) of central and southern New posed of Proterozoic–Paleozoic rocks intruded quality of a cement job. WT logs measured in air Mexico.

52 New Mexico Geology May 2012, Volume 34, Number 2 LARGE-VOLUME QUATERNARY TRAVER- authors (WLL), discovered a very large phytosaur large earthquakes is a reflection of areas naturally TINE DEPOSITS IN THE RIO GRANDE mandible straigraphically about 1.2 m below the more seismically active. I am also looking into trig- RIFT AND JEMEZ LINEAMENT, NEW MEX- amphibian level. That level is now designated gering and triggering delay dependence on the ICO AND ARIZONA: IMPLICATIONS FOR NMMNH locality 8276. The mandible and associ- large earthquake’s location and wave amplitude. PALEOCLIMATE, LANDSCAPE EVOLU- ated postcrania were subsequently collected and TION, AND NEOTECTONICS, A. Priewisch, prepared. In 2010, WLL found a nearly complete L. J. Crossey, E. Embid, K. E. Karlstrom, V. Polyak, but badly crushed skull less than 2 m from the TRACE ELEMENTS IN THE COPPER FLAT Y. Asmerom, J. Ricketts, and A. Nereson, Depart- mandible. The fossils are from silty mudstone PORPHYRY DEPOSIT, HILLSBORO MIN- ment of Earth and Planetary Sciences, Uni- strata representing overbank deposits similar to ING DISTRICT, SIERRA COUNTY, NEW versity of New Mexico, Albuquerque, New those of the overlying amphibian bone bed. The MEXICO, G. Pruthvidhar, [email protected], Mexico 87131 mandible as prepared is 1,240 mm long. The skull Department of Earth and Environmental Sci- New Mexico and Arizona host several large-vol- as measured in the field is approximately 1,390 mm ence, New Mexico Institute of Mining and Tech- ume (0.2–0.9 km3) travertine deposits with sur- long from the snout tip to the distal squamosals, nology, 801 Leroy Place, Socorro, New Mexico face areas of 10–40 km2 and thicknesses ranging which were broken, but apparently in life position, 87801; V. T. McLemore, and N. Dunbar, New Mex- from 5 to more than 60 m. They are present both and 630 mm across at the widest point (quadrato- ico Bureau of Geology and Mineral Resources, along the northeast-trending Jemez lineament jugals) and is among the largest phytosaur skulls New Mexico Institute of Mining and Technolo- and north-south-trending Rio Grande rift and found to date. The relative sizes of the skull and gy, 801 Leroy Place, Socorro, New Mexico 87801 mandible and their close association indicate that record natural CO2 leakage related to Quaternary Copper Flat deposit is a small porphyry copper magmatic CO degassing. U-series data show that they probably belonged to the same individual. 2 Published data and our observations indicate that deposit in the Hillsboro mining district, New Mex- travertine deposition overlapped temporally from ico. Copper Flat has proven and probable reserves place to place. High volume deposition was not other giant phytosaur skulls measure between 1,215 mm and 1,420 mm long, with incomplete of 45.5Mt of ore at a reported grade of 0.45% Cu, steady, but occurred episodically at 36–100 ka, 0.14g/t Au, 2.3 g/t Ag, and 0.0015% Mo. The dis- 200–380 ka, and 520–660 ka. Stable isotope anal- skulls estimated up to 1,500 mm. The posterior half of the Lamy skull is badly crushed and con- trict consists of Cretaceous andesites surrounded yses from the travertines overlap substantially, by Paleozoic sedimentary rocks and Quaternary δ13 sists largely of small, disarticulated pieces but an exhibiting high C values, +2.0‰ to +8.3‰, and alluvial fan deposits. A quartz monzonite stock δ18 intact connection of bone between the snout tip O values that range between −13.5‰ to −4‰. (74.93 ± 0.66 Ma) with a breccia pipe is located in High δ13C values are interpreted to be caused and quadrates yields an accurate minimum length. Associated paramedian scutes, NMMNH P-61225 the center of the district, and a series of latite dikes by rapid CO2 degassing, whereas the range of radiate outward from the quartz monzonite. The δ18O values is interpreted to represent changing and NMMNH P-61238, show healed bite marks. Some duplication of anatomical elements indicates quartz monzonite porphyry and the latite dikes water temperatures and mixing trends of ground are co-genetic. Replacement deposits, which occur water. Times of high accumulation rates are inter- that more than one phytosaur individual is repre- sented by the fossils from locality 8276. near the porphyry deposit, are also genetically preted as times of high ground water flow and related to porphyry deposit. hence as a proxy for regional paleohydrology/ The Copper Flat porphyry copper deposit con- paleoclimate control, whereas the primary con- sists of Cu, Au, Mo, and Ag disseminations and trol on the spatial localization of large-volume DYNAMIC EARTHQUAKE TRIGGERING quartz veins in the breccia pipe. Propagating out- travertine is high tectonic CO2 flux in areas of ABOVE THE SOCORRO MAGMA BODY, ward radially from the Copper Flat porphyry are mantle upwelling, crustal magma chambers, and NEW MEXICO, E. A. Morton, emorton@nmt. Laramide veins hosted by many of the latite dikes. fault conduits. Large-volume travertine occur- edu, and S. L. Bilek, Department of Earth and Chemical analyses range from 8–64,600 ppb Au, < rences are important indicators of the extent of Environmental Science, New Mexico Institute of 0.2–590 ppm Ag, 40–57,337 ppm Cu, < 1–475 ppm Mining and Technology, 801 Leroy Place, Socor- past natural CO2 leakage that can inform carbon Mo, 57–8,906 ppm Pb, and 138–17,026 ppm Zn. ro, New Mexico 87801 sequestration models. By analogy to the active Carbonate-hosted replacement deposits are found Springerville CO2 gas field in Arizona, the large When earthquakes occur they release energy in the distal from the center. Chemical analyses range volumes and similar platform geometries of the form of waves that cause ground movements. For from < 5–99 ppb Au, 1–< 50 ppm Ag, 131–173 travertine occurrences in New Mexico are inter- high magnitude earthquakes, these waves can trav- ppm Cu, 2–140 ppm Mo, 30–> 10,000 ppm Pb, and preted to record extinct or dormant CO fields. 2 el around the world and interact with other faults 123–> 20,000 ppm Zn. As much as 130 ppm Te and Travertine platforms now occupy positions high at great distances from where the earthquake origi- 3,400 ppm Bi also are found. in the landscape (inverted topography) and also nally occurred. This interaction through ground In this study, samples from the Hillsboro district provide data on the scales and timing of regional displacements can alter the stress state on these were examined petrographically, and pyrite, chal- landscape evolution. Erosion rates measured remote faults, reduce the friction on the faults, and copyrite, and molybdenite were identified. Sam- from travertine-capped mesas reveal differential cause them to fail, or trigger another earthquake. ples were then examined by electron microprobe denudation across the study areas and may have This dynamic triggering process can occur in a in order to determine the distribution of elements implications for Quaternary uplift associated with variety of tectonic settings but particularly occurs of economic interest. Initial investigation involved the Jemez lineament. in areas characterized by the presence of hot flu- qualitative geochemical analysis using wavelength- ids and/or magma. Therefore we hypothesize that dispersive scans and chemical maps of 1.5 × 1.5 cm triggering should be common within the region areas to identify particles with high concentrations A GIANT PHYTOSAUR (REPTILIA: ARCHO- above the Socorro Magma Body (SMB) within of Au, Ag, and Mo. No discrete particles contain- SAURIA) SKULL FROM THE GARITA the Rio Grande rift. To test this, I examined data ing Au or Ag were identified, suggesting either that CREEK FORMATION (UPPER TRIASSIC: from 319 large earthquakes from around the world these elements are present at lower concentrations ADAMANIAN) OF NORTH-CENTRAL NEW with magnitudes > 6.0 between January 15, 2008, in other minerals or that particles containing these MEXICO, D. C. Bond, L. F. Rinehart, W. L. Layman, and November 30, 2009, and analyzed the seismo- elements are present at low enough concentrations and S. G. Lucas, New Mexico Museum of Natural grams recorded on seismometers stationed around that they were not present in the scanned area. Fol- History, 1801 Mountain Road NW, Albuquerque, Socorro, New Mexico, to see if local earthquakes lowing qualitative investigation, quantitative analy- New Mexico 87104 corresponded with the passage of waves from the sis for trace elements was carried out, using long Phytosaurs are large, semi-aquatic, carnivorous large earthquake. 93 local events were found cor- count times in order to obtain detection limits below reptiles known from Upper Triassic strata in North responding to 66 of the large earthquakes. I have 100 ppm. The results show detectable Au, Ag, Mo, America, Brazil, Europe, Turkey, North Africa, been looking at background rates of seismicity in but Te, Se, Cd, Bi are not detected. Madagascar, India, and Thailand. The Chinle the area to determine if the amount of local earth- Group of New Mexico yields many phytosaur quakes increases with the passage of large earth- fossils. A giant skull, mandible, and associated quake waves, indicating that some events are a COMPARING DETRITAL ZIRCON U-Pb AGE postcranial fossils representing a Rutiodon-grade result of “delayed triggering” rather than being DATA TO DETERMINE PROVENANCE phytosaur, possibly Leptosuchus, was collected by independent of the large earthquake. The major- RELATIONSHIPS OF UPPER JURASSIC the New Mexico Museum of Natural History and ity of local events occur above the Socorro Magma AND LOWER CRETACEOUS STRATA, Science (NMMNH) in 2009 and 2010. NMMNH Body, showing that it is more conducive to trigger- SOUTHWEST NEW MEXICO AND SOUTH- locality 1176 in the Garita Creek Formation of the ing in New Mexico, but the events can be spread EAST ARIZONA, J. C. Gilbert, and T. F. Lawton, Chinle Group, (Santa Fe County) normally yields throughout the rift as well. We hypothesized that Department of Geological Sciences, New Mexico metoposaurid amphibian (Koskinonodon perfec- large earthquake locations would show a region State University, Las Cruces, New Mexico 88003 tum) remains in an extensive bone bed designated that preferentially triggers events in New Mexico; Analysis of detrital zircon U-Pb age data of the the Lamy amphibian quarry. In 2009, one of the however, the only clustering of possibly triggering Early Cretaceous Hell-to-Finish Formation of

May 2012, Volume 34, Number 2 New Mexico Geology 53 the Little Hatchet Mountains in New Mexico with the much wider range of published ages The “Boquillas Formation” (= Mancos Shale) is and the Late Jurassic Glance Conglomerate and implying the bulk of the NVF was emplaced by a shale-dominated strata of Late Cretaceous (middle Early Cretaceous Morita Formation of the Hua- short pulse of widespread magmatism rather than Cenomanian) age known in New Mexico from out- chuca Mountains in Arizona indicates different series of temporally spaced eruptions. Additional crops on the northern flank of Cerro de Cristo Rey, provenance histories. Formerly, the Hell-to-Fin- geochronology will assess whether additional Doña Ana County. We report newly discovered out- ish Formation has been considered genetically eruptive pulses occurred in the NVF. crops of the Boquillas exposed by excavation of an similar and correlative with the red beds of the unpaved road just south of Flag Hill in the Franklin Glance Conglomerate and Morita Formation PENNSYLVANIAN SANDIA FORMATION IN Mountains of El Paso County, Texas (NM Museum based on outcrop appearance and stratigraphic THE SIERRA NACIMIENTO, NEW MEXI- of Natural History locality 7730). This outcrop position. In the southwest Huachuca Moun- CO: EVIDENCE OF TECTONISM OF THE exposes about 4.5 m of Boquillas strata that con- tains, a detrital zircon sample from a volcanic ARM PEÑASCO UPLIFT, K. Krainer, Karl. sist of: (1) thinly laminated (mm-scale) mudstone litharenite high in the Glance Conglomerate [email protected], Institute of Geology and in which gray mudstone laminae alternate with contains dominantly Early to Middle Jurassic Paleontology, University of Innsbruck, Inns- slightly coarser, silty, brownish mudstone laminae; grains (81 of 96 grains) derived from underlying bruck A-6020 Austria; S. G. Lucas, and J. A. Spiel- (2) some thin gypsum layers; (3) fine-grained, lami- volcanic rocks. Unconformably overlying the mann, New Mexico Museum of Natural History, nated carbonate beds that are composed of mud- Glance Conglomerate, the lower Morita Forma- 1801 Mountain Road NW, Albuquerque, New stone containing locally abundant planktic globi- tion transitions from nearshore facies rocks at Mexico 87104; and D. Vachard, Université des gerinid foraminifers such as Hedbergella, peloids, the base to fluvial facies rocks. A detrital zircon Sciences et Technologies de Lille, 59655 Ville- a few small bivalve shells, gastropods, ostracods, sample of 90 grains from a nearshore subarkose neuve d’Ascq Cédex, France and small echinoderm fragments. These carbonate contains mostly Triassic (n =12) and Proterozoic beds are up to 15 cm thick and contain abundant grains (n = 60) but only a few Early Jurassic The Lower-Middle Pennsylvanian (?late Mor- shells on bed tops. The carbonate beds laterally grains (n = 6), reflecting burial or late stage ero- rowan–early Atokan) Sandia Formation in the Sier- lense out. Some of the carbonate beds form lenses sion of Jurassic rocks. Higher in the section, a ra Nacimiento, north-central New Mexico, is char- less than 1 m wide, probably representing the fills fluvial volcanic litharenite contains abundant acterized by distinct lateral changes in thickness of paleotopographic lows. The mudstone also con- Cretaceous grains (ca. 145–120 Ma) from the and facies as a result of the ancestral Rocky Moun- tains ammonites, bivalves, gastropods, and other arrival of volcanic material to the west. In the tain (ARM) deformation. In the Sierra Nacimiento, fossils that are partly fragmented, indicating that Little Hatchet Mountains, the lower Hell-to- the Sandia Formation is thinner than at the type the fossils have been transported. These strata are Finish Formation is fluvial, and the sandstones section in the Sandia Mountains near Albuquerque very similar to the Boquillas Formation at Cerro de (124 m). The thickest sections (72 m) are exposed are litharenites that contain abundant chert and Cristo Rey, where the exposed thickness is 18.6 m. on the eastern side of the Sierra Nacimiento north carbonate clasts and no volcanic fragments. Fossils from the Boquillas Formation at the of Jemez Springs (Soda Dam), where the Sandia A detrital zircon sample of the Hell-to-Finish newly discovered outcrop represent the following Formation rests on Precambrian gneiss and is com- Ostrea Formation is composed almost exclusively of posed of shale with intercalated sandstone and taxa: unidentified gastropods; the bivalves pre-Triassic grains (78 of 79 grains) and was fossiliferous limestone containing the fusulinids beloiti Logan, Inoceramus arvanus Stephenson, I. sourced from the Burro uplift to the north. In Millerella, Eostaffella, and Fusulinella, indicating an praefragilis Stephenson, and Pinna sp.; the ammo- contrast, the Morita Formation received a sig- Atokan age. Toward the west and north the San- noids Acanthoceras amphibolum Morrow, Desmo- nificant component of material from a western dia Formation thins and is entirely siliciclastic, ceras sp./Moremanoceras sp., and Idiohamites sp. source that is not reflected in the Hell-to-Finish composed of alternating shale, siltstone, and sand- These taxa are also found at Cerro de Cristo Rey Formation, suggesting the basins were isolat- stone (Mesa Venado, Porter Landing, Rancho de and support assignment to the middle Cenoma- ed. Material for the Glance Conglomerate was Chaparral). North of Guadalupe Box, the Sandia nian Acanthoceras amphibolum Zone. In southern locally derived and is not an input for the Hell- Formation overlies the Osha Canyon Formation, is New Mexico and west Texas, the name Mancos to-Finish Formation. 32 m thick, and composed of several fluvial fining- Formation is best applied to this shale-dominated upward cycles and a thin marine horizon at the interval at the base of the Greenhorn cycle of depo- sition. More parochial stratigraphic names such as Ar-Ar PHLOGOPITE GEOCHRONOLOGY OF top. The northernmost outcrops are at Resumidero THE NAVAJO VOLCANIC FIELD AND THE east of San Pedro Peak where the Sandia Forma- Boquillas, Chispa Summit, and Ojinaga are best SHIP ROCK DIATREME OF NORTHWEST tion is approximately 13 m thick and overlain by abandoned to unify the stratigraphic terminology NEW MEXICO DEFINE A 1.4 MA PULSE OF Gray Mesa Formation. Locally, near the western so that it better reflects the regional distribution of POTASSIC MAGMATISM, J. P. Nybo, and W. and southern margin of the Sierra Nacimiento, the this lithosome throughout southern New Mexico, C. McIntosh, Department of Earth and Environ- Sandia Formation is absent. At Log Springs near west Texas, and northern Chihuahua. mental Science, New Mexico Institute of Mining the southern end of the Sierra Nacimiento the Log and Technology, 801 Leroy Place, Socorro, New Springs Formation is unconformably overlain by Mexico 87801; and S. Semken, School of Earth thin Osha Canyon Formation and Gray Mesa For- ERUPTION CHARACTERISTICS OF THE and Space Exploration, Arizona State Univer- mation, indicating phases of uplift during Late CIENEGA CINDER CONE, CERROS DEL Mississippian and Early Permian time. At Coyote sity, Tempe, Arizona 85287 RIO VOLCANIC FIELD, NEW MEXICO, M. Flat west of Jemez and at Rio de las Vacas the base- Foucher, A. Romero, and J. Lindline, Environmen- Newly acquired Ar-Ar phlogopite ages indicate ment is overlain by the Guadalupe Box Formation, tal Geology Program, Natural Resources Man- a brief but widespread pulse of magmatism at an equivalent of the Atrasado Formation (late Des- agement Department, New Mexico Highlands 25.9 to 24.5 Ma in Navajo volcanic field (NVF). moinesian–middle Virgilian). In the area of Camp University, Las Vegas, New Mexico 87701 Covering approximately 30,000 km2 of the Four Zia northwest of Cuba, the Precambrian basement Corners region in the southwestern US, the NVF is overlain by red beds of the Abo Formation, indi- This study describes the eruption characteristics encompasses numerous diatremes, plugs, dikes, cating that the Peñasco uplift existed there as a pos- of the Pleistocene Cienega cinder cone. This vol- and occasional sills and maars including the well- itive high during the entire Pennsylvanian. Thus, cano is located in the southeastern part of the Cer- known Ship Rock diatreme. Petrographically thickness and facies changes and the distribution ros del Rio volcanic field (CdR) west of Santa Fe, the field is dominated by minette and serpen- of the Sandia Formation in the Sierra Nacimiento New Mexico. The CdR is the largest (> 700 km2) of tinized ultramafic microbreccia though outcrops can be attributed to ARM tectonic movements of several middle Pliocene to Pleistocene basaltic vol- of monchiquite, katungite, and olivine melilitite the Peñasco uplift. canic fields of the axial Rio Grande rift in northern occur as dikes in small numbers. Published K-Ar New Mexico. Eruptive centers are typically central ages from the NVF range from 33.9 to 19.4 Ma. vent volcanoes, ranging from low-relief shields to Phlogopite separates of six dikes from the Ship NEW OUTCROPS OF THE UPPER CRETA- steep-sided, breached cinder and spatter cone rem- Rock diatreme along with two dikes and two CEOUS “BOQUILLAS FORMATION” IN nants. The Cienega cinder cone is actually a volca- plugs from other locations throughout the NVF THE FRANKLIN MOUNTAINS NEAR EL nic complex that consists predominantly of tephra were analyzed in this study by the Ar-Ar method PASO, TEXAS, S. G. Lucas, spencer.lucas@ fall deposits as well as several vents, multiple using CO2 laser and resistance furnace incremen- state.nm.us, New Mexico Museum of Natural intrusions, and numerous lava flow sequences. A tal heating. The resulting age spectra were gener- History, 1801 Mountain Road NW, Albuquer- slightly eroded northern vent is 230 m in diameter ally flat, and a selection of the most precise ages que, New Mexico 87104; K. Krainer, Institute of and consists of inward bedded crater facies and range from 25.9 ± 0.1 Ma at Todilto Park, Arizo- Geology and Paleontology, University of Inns- periclinally bedded wall facies. A smaller southern na, to 24.4 ± 0.1 Ma at Ship Rock, New Mexico. bruck, Innsbruck A-6020 Austria; J. A. Spiel- vent is 95 m in diameter and composed of steep The selected samples spatially represent the full mann, and B. Cornet, New Mexico Museum north-dipping pyroclastic layers that suggest the breadth of the NVF and span a range 1.4 Ma. The of Natural History, 1801 Mountain Road NW, development of a late-stage shallow cryptodome. narrow range of ages found in this study contrasts Albuquerque, New Mexico 87104 Vent facies include vesiculated fragments, oxidized

54 New Mexico Geology May 2012, Volume 34, Number 2 cinders, and spatter agglutinate interbedded with than the largest one yet reported. Although mea- Preliminary results exhibit substantial spatial lava flows. Proximal wall facies are moderately surements of the thickness of dermal elements of variability evident by progressive downstream sorted with a high proportion of coarse scoria and the pectoral girdle are not commonly available, the increases in solute concentrations. We report on bombs, whereas the distal wall facies are very well Jemez metoposaur also appears remarkable in this a 66.5 mi reach of the upper Gila River, from Gila sorted with a high proportion of fine lapilli. Flu- regard, measuring more than 2.5 cm from deep to Springs to Bill Evans Lake. This is an area of major vial sand and gravel deposits as well as aeolian superficial surfaces. geologic sources of saline water input into the sand deposits within some of the pyroclastic layers system. Regional climate change scenarios pre- illustrate the development of stream channels and dict a reduction in precipitation including effects exposed surfaces in between eruptions. One major THE SIPHUNCLE IN A SPECIMEN OF on snowpack melt and runoff contribution to the north-striking anastomosing dike (> 10 m long by DOMATOCERAS FROM THE SAN ANDRES Gila system. This will significantly increase the 4 m wide) as well as several minor north-striking FORMATION, NEW MEXICO, J. H. McDon- occurrence of base flow regime leading to higher dikes (< 2 m long by 1 m wide) intrude the south- nell, New Mexico Museum of Natural History salinity. Such conditions are projected to apply ern complex. Macrostructures (slickenlines, chatter and Science, 1801 Mountain Road NW, Albu- stress on a wide range of ecological communi- marks, and Reidel shears) consistently show wall querque, New Mexico 87104 ties and have negative consequences for water rock deformation having a north-sense of shear, quality for downstream users. Detailed study The nautiloid cephalopod Domatoceras Hyatt indicating south-moving magma toward the inflat- of water chemistry of geologic water inputs in 1891 is well known from the Pennsylvanian and ing southern vent. Samples from all volcanic facies the upper Gila watershed provides crucial base- Permian of North America. Descriptions, how- (vent, lava flows, proximal wall, and distal wall) line information for determining the response to ever, are pretty much limited to the external contain major olivine (1–3%), pyroxene (1–3%), climate change and data to distinguish geologic morphology of the shell as in Bernhard Kummel and plagioclase (5%) phenocrysts in an aphanitic solute concentrations from anthropogenic contri- (1964: Nautiloidea - Nautilida. Treatise on Inver- matrix. Scoria cinders contain 20–50% vesicles in butions to the system. tebrate Paleontology Part K) and others. Mention a holohyaline matrix. Our observations show that of the siphuncle is limited to its position and the the Cienega cinder cone is a monogenetic volca- possibility of its being orthochoanitic. nic complex that developed by endogenic and The segments of the siphuncle and part of a ANISOTROPY OF MAGNETIC SUSCEPTIBIL- exogenic dome growth with short eruptive events fourth are exposed in a break in specimen P 56221 ITY, ROCK MAGNETIC, AND PALEOMAG- that likely were derived from a rapidly evolving of the New Mexico Museum of Natural History NETIC DATA FROM MAFIC DIKES IN THE reservoir-conduit system. and Science, which have allowed description ESPAÑOLA BASIN, RIO ARRIBA COUNTY, for perhaps the first time. Segments are 5 mm NEW MEXICO, R. Trujillo, rhondatrujillo@hot- in length, fusiform, expanding from 2 mm at the mail.com, M. S. Petronis, and J. Lindline, Envi- AN UNUSUALLY LARGE METOPOSAURID septal foremina to as much as 3.5 mm at the mid- ronmental Geology Program, Natural Resource FROM THE SALITRAL FORMATION OF point. Septal neck are not recognized; however, Management Department, New Mexico High- THE CHINLE GROUP (UPPER TRIASSIC: the slight expansion suggest that, when present, lands University, Las Vegas, New Mexico 87701 CARNIAN?) ON LANDS BELONGING TO they were slightly cyrtochoanitic, rather than This study characterizes a suite of Miocene mafic THE PUEBLO OF JEMEZ, K. M. Madalena, orthochoanitic as inferred in the literature. dikes in the Española Basin, north-central New K373 Buffalo Hill Road, Pueblo of Jemez, New Mexico, using paleomagnetic, rock magnetic, Mexico 87024; K. E. Zeigler, Environmental Geol- and field observations. Paleomagnetic data pro- ogy Program, Natural Resources Management EVALUATING SOLUTE SOURCES IN THE vided constraints on potential components of Department, New Mexico Highlands University, UPPER GILA RIVER, NEW MEXICO, P. vertical-axis rotation across structural blocks, Las Vegas, New Mexico 87701; and S. S. Sumida, Vakhlamov, [email protected], and between separate dikes, and along strike varia- California State University-San Bernardino, San L. J. Crossey, Department of Earth and Planetary tions within individual dikes. Anisotropy of Bernardino, California 92407 Sciences, University of New Mexico, Albuquer- magnetic susceptibility (AMS) data and field que, New Mexico 87131; C. N. Dahm, Depart- observations provided information on magma Lands belonging to the Pueblo of Jemez in north- ment of Biology, University of New Mexico, central New Mexico include sedimentary strata flow patterns within each dike and discernment Albuquerque, New Mexico 87131; V. Acuña, of any variation in magma flow patterns within that range in age from Mississippian to Pleistocene, Catalan Institute for Water Research, Parc- and include excellent exposures of Upper Triassic the swarm. We tested the following hypotheses: CientíficiTecnològic de la Universitat de Giro- (1) the mafic dikes experienced some degree of strata. The Salitral Formation of the lower Chinle na, Girona, Spain; and A. S. Ali, Department Group (Upper Triassic: Carnian) are present in the vertical axis rotation associated with Rio Grande of Earth and Planetary Sciences, University of rifting and (2) the magma flow pattern within southeastern corner of the Jemez Reservation in an New Mexico, Albuquerque, New Mexico 87131 area that is complexly faulted. Samples for paleo- the dikes reflects lateral emplacement with flow magnetic analyses have been taken from the area The Gila River in southwestern New Mexico directed away from the magma ascent location. in order to clarify the stratigraphic relationships is one of the last free flowing rivers in North Rock magnetic data provided constraints on and are currently in progress. Material pertain- America. It exhibits a great range of hydrochemi- the magnetic mineralogy responsible for carry- ing to a metoposaurid amphibian was recovered cal variability across spatial and temporal scales ing the AMS and the remanence directions. Low- from a grayish-purple calcrete nodule horizon in in response to changes in precipitation and tem- field susceptibility versus temperature experi- the lower Salitral Formation, approximately 7–8 m perature. Previous work indicates that during ments yielded a spectrum of results reflecting a above the underlying Shinarump (= Agua Zarca) times of monsoonal precipitation, temporal vari- thermomagnetic behavior typical of intermedi- Formation. The fossil-bearing horizon is comprised ability in water chemistry of streams in the Gila ate composition titanomagnetite, whereas oth- primarily of a poorly consolidated conglomeratic watershed is largely affected by surface runoff ers exhibited a more complex behavior with the lens dominated by calcareous nodules from 1 to due to variability in landscape cover features, presence of two or more magnetic phases. Curie 10 cm diameter. This unit also contains moderately as well as size of the catchment. However, dur- point estimates ranged from ~ 100°C to 575°C abundant fragments of metoposaur and phyto- ing base flow regimes, spring inputs of various indicating a range of moderate to low Ti- titano- saur material. Metoposaurid material includes magnitudes are the dominant drivers of solute magnetite compositions as well as the presence cranial and shoulder girdle elements as well as concentrations and variability in this system. of a Fe-sulfide phase. Additional rock magnetic teeth. Phytosaur material includes teeth and osteo- There are several influencing factors effecting experiments included the Lowrie-Fuller test to derms with a characteristically high dorsal ridge. base flow solute concentrations. In the Gila River, estimate the magnetic domain state, acquisition The metoposaurid specimens are fragmentary, but as with many perennial rivers of the American of isothermal remanent magnetization (IRM), are significant for their extraordinary size. A par- Southwest, deep ground water and geothermal and backfield IRM experiments to verify the tial interclavicle is conservatively reconstructed as inputs are determined to be primary contribut- magnetic mineralogy, domain state, and the well over 450 cm in width. The largest specimen ing sources of solutes. Such waters derive their coercivity of the remanence. These experiments, reported from Texas is 430 cm, and a specimen pre- compositions from being conducted through as well as other data, indicated that the rema- viously reported as the largest from New Mexico is fault and fracture networks created by tectonic nence is likely a primary thermoremanent mag- 400 cm in width. Published sizes of metoposaurid processes. Our primary objective is to quantify netization acquired during cooling and is thus interclavicles from the Chinle Formation of New contributions of deep water and geothermal geologically stable. Mexico and the Dockum Formation of west Texas inputs to surface water chemistry of the upper The AMS fabric data reveal a combination of average 307 cm and 313 cm, respectively. Thus, Gila stream network and determine annual vari- both prolate and oblate susceptibility ellipsoids. the Jemez metoposaur is one of the largest ever ability of solute fluxes by utilizing a combination At several sites, the fabrics are oblate from paired reported, approximately 47–48% larger than those of methods including continuous water quality dike margins and reveal a unique magma flow published averages, and approximately 5% larger monitoring sensors and campaign sampling. direction. The maximum susceptibility axis (K1)

May 2012, Volume 34, Number 2 New Mexico Geology 55 and the imbrications of the magnetic foliation the Beartooth Formation remained poorly con- Cuba, New Mexico. Scaphites leei III has also been (K1–K2) planes indicate both upward and down- strained, but detrital zircon analyses indicate reported from near the base of the “Mesaverde ward sense of flow, as well as flow toward and a maximum depositional age of 100 Ma. The Formation” east of Cuba and from the Hagan away from the likely source region. Susceptibil- Mojado Formation is a 1,245-m-thick sequence coal field. This would correspond to the base of ity values are high and consistent with a ferro- of marginal marine quartzarenite in the Little the Point Lookout Sandstone. S. leei III has also magnetic phase. Preliminary results indicate that Hatchet Mountains that represents renewed been reported from the upper part of the Mancos the group mean is discordant in a counter-clock- subsidence of the Bisbee Basin in the late Albian. Shale on the eastern side of the San Juan Basin wise sense to the expected Miocene field direc- The conformable contact with the underlying, and from the Ortiz Mountains. S. leei III is the tion. Additional paleomagnetic experiments are middle Albian U-Bar Formation and the 99 Ma lowest Campanian zone taxon. This indicates an underway and should help further constrain the detrital zircon grains from the upper part of the earliest Campanian age for the Point Lookout emplacement of the dikes and tectonic evolution Mojado Formation are evidence of rapid subsid- Sandstone near Cabezon. of the study area. ence that exceeds the rate of thermal subsidence, indicating tectonic influence on basin formation. Additionally, an air-fall tuff in the lowermost DIACHRONOUS EPISODES OF CENOZOIC INVESTIGATION OF SOIL POLLUTION strata of the overlying Mancos Formation, which EROSION IN SOUTHWESTERN NORTH SOURCES IN THE EL PASO REGION represents a marine transgression, is ~ 97 Ma. AMERICA AND THEIR RELATIONSHIP USING SEM, MAGNETIC SUSCEPTABIL- Foreland basins that form after relict rift basins TO ROCK UPLIFT, PALEOCLIMATE, AND ITY, AND XRF ANALYSIS, J. L. Tasker, M. are poorly understood. The Cenomanian strata PALEOALTIMETRY, S. M. Cather, steve@gis. Gomez, and K. Devaney, El Paso Community are characteristic of a foreland basin system, with nmt.edu, C. E. Chapin, and S. A. Kelley, New Mex- College, Transmountain Campus, El Paso, Texas the Mojado Formation deposited in the foredeep ico Bureau of Geology and Mineral Resources, 79924; and L. R. Bothern, El Paso Community and the Beartooth Formation deposited on the New Mexico Institute of Mining and Technology, College, Transmountain Campus, El Paso, Texas forebulge. Rather than attributing the increased 801 Leroy Place, Socorro, New Mexico 87801 accommodation in the late Albian to thermal 79924, and Department of Geological Sciences, The history of erosion of southwestern North subsidence of the Bisbee rift basin, an alterna- New Mexico State University, Las Cruces, New America and its relationship to uplift processes is tive model of a flexural origin for the Mojado– Mexico 88003 a long-standing topic of debate. We use geologic Beartooth section is supplied by the asymmetric and thermochronometric data to reconstruct the In urban area soil pollution is a major concern geometry of those strata. A foreland basin origin erosion history of southwestern North America. for the health of residents, development of the for the uppermost Albian strata in turn provides Erosion events occurred mostly in response to land, water usage, and agricultural production. evidence for earliest Laramide shortening in rock uplift by tectonism, although important iso- This makes investigation of soils important for southwestern New Mexico near the beginning of static components of uplift can be demonstrated maintaining the well-being of people, plants, the Late Cretaceous. and animals that reside within the area of study during the late Miocene–Recent. We recognize and beyond. In this study, we will investigate four regional episodes of erosion and associ- ated rock uplift: (1) the Laramide orogeny (ca. soil pollution using three methods: magnetic EARLY CAMPANIAN AMMONITES AND 75–50 Ma), during which individual uplifts were susceptibility, scanning electron magnification, OTHER MOLLUSCS FROM THE POINT deeply eroded as a result of uplift above thrusts, and X-ray fractionation. Potential sources of pol- LOOKOUT SANDSTONE NEAR CABEZON, but Laramide basins and the Great Plains region lution in El Paso region include a former artillery SANDOVAL COUNTY, NEW MEXICO, P. L. remained near sea level as shown by the lack of range, oil refineries, smelters, power plants, free- Sealey, and S. G. Lucas, New Mexico Museum significant Laramide exhumation in these areas; ways, and other dismantled industry. of Natural History and Science, 1801 Mountain (2) late middle Eocene erosion (ca. 42–37 Ma) in Magnetic susceptibility is a quick, easy meth- Road, NW, Albuquerque, New Mexico 87104 od to detect pollution in soils involving simple Wyoming, Montana, and Colorado occurred in sample preparation and provides rapid, repeat- Ammonites and other molluscs were collected response to epeirogenic uplift from rebound that able analyses. The iron oxides generated through from near the base of the Point Lookout Sand- followed the cessation of Laramide dynamic sub- combustion display high magnetic properties that stone near Cabezon, New Mexico. The ammonites sidence; (3) late Oligocene–early Miocene deep act as a proxy for heavy metal pollution from the Placenticeras syrtale, Baculites sp. and Scaphites leei erosion (ca. 27–15 Ma) that affected a broad region source. The scanning electron microscope (SEM) III, the gastropod Gyrodes sp. and other uniden- of the southern Cordillera (including the southern allows for up to 10,000× magnification of samples tified gastropods, and the bivalves cf. Tellina sp., Colorado Plateau, southern Great Plains, Trans- and also has an X-ray attachment that allows for cf. Siliqua sp., cf. Mactra sp., Cardium sp., inocera- Pecos Texas, and northeastern Mexico) that was elemental analyses of specific sample grains. The mids and other bivalve taxa were recovered. In uplifted in response to increased mantle buoyan- 1917, W. T. Lee reported a locality near Cabezon X-ray fractionation instrument available at New cy from major concurrent volcanism in the Sierra where the old wagon road crossed the top of the Mexico State University will provide us with Madre Occidental and adjacent volcanic fields; Mancos Shale. He collected a small molluscan detailed analyses of trace elements within soil (4) late Miocene–Recent erosion (ca. 6–0 Ma) of a fauna from what he called the transitional zone samples. After collection of samples and analysis between the uppermost Mancos Shale and the broad area of southwestern North America, with of data, we hope to better understand processes basal Mesaverde. We believe that the horizon we a locus of deep erosion in the western Colorado– involved in heavy metal pollution of sample area collected—a fossiliferous, calcareous sandstone ~ eastern Utah region that reflects mantle-driven soils and identify point sources of the pollutants. 6 m above the base of the Point Lookout Sand- rock uplift as well as an important isostatic com- stone—is the same horizon collected by Lee. Lee’s ponent related to deep fluvial erosion. We cannot list included the bivalves Ostrea elegantula, Anomia estimate the amount of rock or surface uplift asso- THE BEARTOOTH–MOJADO CONNEC- sp., Pinna sp., Cardium sp., Cyprimeria sp., Tellina ciated with each erosion episode, but the maxi- TION: USING MID-CRETACEOUS SEDI- sp., Liopistha undata, Mactra sp., and Corbula sp. as mum depth of exhumation for each was broadly MENTARY ROCKS TO UNDERSTAND THE well as the gastropods Gyrodes sp. and Actaeon sp. similar (typically ~1–3 km). Only the most recent TECTONIC HISTORY OF SOUTHWEST But, he did not report Scaphites or Baculites from erosion episode is correlated with climate change. NEW MEXICO, S. E. Machin, smachin@nmsu. the locality. The only ammonite he reported was Paleoaltimetric studies, except for those based on edu, J. M. Amato, and T. F. Lawton, Department Placenticeras sancarlosense, a species subsequently leaf physiognomy, are generally compatible with of Geological Sciences, New Mexico State Uni- synonymized with P. syrtale. the uplift chronology we propose here. Physiog- versity, Las Cruces, New Mexico 88003 P. syrtale also occurs in the Dalton Sandstone nomy-based paleoelevation data commonly show Mid-Cretaceous quartzarenites in the Bisbee in the Cabezon area. It has also been reported that near-modern elevations were attained during Basin of southwestern New Mexico record the from the upper part of the Mancos Shale in the the Paleogene, but are the only data that uniquely transition from Late Jurassic–Early Cretaceous upper Rio Grande valley and along the west- support such interpretations. High Paleogene rifting to the onset of Laramide shortening in the ern side of the Sierra Nacimiento, including the elevations, however, require a complex uplift/ latest Early Cretaceous. Detrital zircon analyses Satan Tongue of the Mancos Shale near La Ven- subsidence history for the Front Range and west- and measured sections indicate a correlation tana. P. syrtale has been reported to range from ern Great Plains area that is not compatible with between late Albian quartzarenites on opposite the lower Santonian to the lower Campanian. regional sedimentation and erosion events. Our sides of the relict Bisbee rift basin. The Baculites specimens collected from the Point results suggest that near-modern surface eleva- Exposed in the Burro Mountains, along the Lookout Sandstone near Cabezon are closest to tions in southwestern North America were gener- northern flank of the basin, the Beartooth For- variants of Baculites aquilaensis in their prominent ally not attained until the Neogene, and that these mation is a 30-m-thick section of quartzarenite arcuate nodes on the outer flanks. B. aquilaensis high elevations are the cumulative result of four and conglomerate representing a tidal-marginal var. obesus was reported by Reeside from the major episodes of Cenozoic rock uplift of diverse marine environment. Until this study, the age of basal part of the “Mesaverde Formation” east of origin, geographic distribution, and timing.

56 New Mexico Geology May 2012, Volume 34, Number 2 NO EVIDENCE FOR CONFORMABLE CON- geothermal systems. Determination of mineral- unnamed Tertiary age (?) conglomerate is locally TACT BETWEEN THE OJO ALAMO SAND- saturation indices has been found to produce incised into underlying Cretaceous strata, and STONE AND THE NACIMIENTO FORMA- better estimates of known reservoir tempera- its base is an angular unconformity with older TION, T. E. Williamson, New Mexico Museum tures than the use of traditional geothermom- strata. Tertiary igneous intrusives occur as both of Natural History and Science, 1801 Mountain eters. However, there are few geothermal sys- sills and dikes and are presumably related to Road NW, Albuquerque, New Mexico 87104; tems with known reservoir temperatures in the Oligocene Sierra Blanca volcanic field. Sills S. L. Brusatte, American Museum of Natural His- New Mexico. observed in the field area are felsic to intermedi- tory, New York, New York 10024; D. J. Peppe, Bay- We attempted to determine which geother- ate in composition and often have porphyritic lor University, Waco, Texas 76798; R. Secord, Uni- mometers are best at predicting known geother- textures. Dikes in the map area are oriented east- versity of Nebraska, Lincoln, Nebraska 68588; mal reservoir temperatures, as well as determin- west to southeast-northwest and tend to be short and A. Weil, Oklahoma State University, Center ing the likelihood of each geothermometer pro- in length (less than 0.75 km). Permian strata in for Health Sciences, Tulsa, Oklahoma 74107 ducing valid temperature estimates in areas with the Bull Gap area include the San Andres For- The San Juan Basin of northwestern New Mex- unknown reservoir temperatures. We applied mation and the overlying Grayburg Formation ico is a Laramide basin that accumulated sedi- both traditional geothermometers and the of the Artesia Group, which are overlain by the ments through the Cretaceous–Paleogene (K– mineral-saturation approach to areas of known Lower to Middle Triassic Moenkopi Formation. Pg) boundary. However, the precise age of the temperature. We also applied a statistical fil- Cretaceous strata include the Dakota Sandstone, Ojo Alamo Sandstone, which lies near the K–Pg tering process to both nonthermal and thermal which forms the distinctive hogback in the cen- boundary in the San Juan Basin, remains contro- data sets to weed out conventional geother- ter of the map area, the lower tongue of the Man- versial. Determining its age is crucial to under- mometers predicting unlikely temperatures. cos Shale, Tres Hermanos Formation, D-Cross standing the tectonic and biotic history near the No single geothermometer or suite of geother- Tongue of the Mancos Shale, Gallup Sandstone, K–Pg boundary in this area. Based on study of mometers could be considered highly reliable for and the Crevasse Canyon Formation. The lime- these strata in the Bisti/De-na-zin Wash area predicting reservoir temperatures in New Mexi- stones in the lower tongue of the Mancos Shale (BDNZ) near Barrel Springs, previous workers co. Traditional geothermometers such as quartz, are the Bridge Creek Beds. Faults in the Bull Gap have argued that the top of the Ojo Alamo Sand- chalcedony, Na-K-Ca, and Na-K geothermom- quadrangle are primarily oblique-slip faults and stone and the base of the Nacimiento Formation eters work well for predicting high-temperature oriented northwest-southeast to east-west. Both are interfingering and therefore are conformable. resources. The mineral-speciation approach also right lateral and left lateral strike slip motion Based on this interpretation, most workers have worked well for predicting high reservoir tem- are evident, and slickenline lineations observed regarded the Ojo Alamo Sandstone (here regard- peratures. Though this method is more time at a few localities are steeply inclined. A few ed in the restricted sense; = Kimbeto Member) in consuming it is useful when there is no agree- faults trend north-south to northeast-southwest the BDNZ to be early Paleocene in age. The base ment between traditional geothermometers. Our and appear to be primarily normal faults. These of the Nacimiento Formation has been correlated screening process determined that four tradi- faults are primarily down to the west and are to C29n and produces early Paleocene mammals. tional geothermometers are best suited for esti- presumably part of the Neogene extensional This provides a minimum age for the underly- mating low- to moderate-temperature resources: structural fabric. ing Ojo Alamo Sandstone. Given this minimum two chalcedony, one Na-K-Ca, and the K-Mg. age constraint workers have generally taken one It is also apparent that the mineral-speciation of two positions for the precise age of the Ojo approach works well with lower temperature U-SERIES DATING AND STABLE ISOTOPE Alamo Sandstone: (1) the Ojo Alamo Sandstone systems. However, these lower temperature sys- ANALYSIS OF TRAVERTINE DEPOSITS spans the upper part of C29r, or (2) it is restricted tems show less convergence and wider range of NEAR PONDEROSA, NEW MEXICO: IMPLI- to only the lower part of C29n. To resolve this predicted temperatures. Our screening process CATIONS FOR DEFINING THE EASTERN question and to determine a more precise age identified several regions of known moderate- for the Ojo Alamo Sandstone, we examined temperature geothermal resources (Lightning LIMIT OF THE VALLES OUTFLOW PLUME, the stratigraphic relationships between the Ojo Dock, New Mexico State University, Jemez R. E. Salaz, [email protected], Department of Earth Alamo Sandstone and the overlying Nacimiento Springs). We also identified several moderate- and Environmental Science, New Mexico Insti- Formation in the BDNZ. Contrary to previous temperature systems that have not previously tute of Mining and Technology, 801 Leroy Place, interpretations, we find that this formational con- been identified with geothermometry (Montezu- Socorro, New Mexico 87801; S. A. Kelley, New tact is not conformable. Rather, what other work- ma Hot Springs, Hondo Hot Springs). Mexico Bureau of Geology and Mineral Resourc- ers have assumed to be the “upper part of Ojo es, New Mexico Institute of Mining and Tech- Alamo Sandstone” that interfingers with basal nology, 801 Leroy Place, Socorro, New Mexico parts of the Nacimiento Formation is actually A PRELIMINARY GEOLOGIC MAP OF THE 87801; G. WoldeGabriel, Earth and Environmental a remnant of a lenticular channel sandstone of BULL GAP QUADRANGLE, LINCOLN Sciences Division, Los Alamos National Labora- the Nacimiento Formation. This reinterpretation COUNTY, SOUTHEASTERN NEW MEXICO, tory, EES-16/MS D462, Los Alamos, New Mexi- suggests that the formational contact between K. E. Zeigler, [email protected], Environ- co 87545; and M. Albrecht, TBA Power, Inc, 2825 the Nacimiento Formation and the Ojo Alamo mental Geology Program, Natural Resources East Cottonwood Parkway, Suite 500, Salt Lake Sandstone may represent a significant hiatus of Management Department, New Mexico High- City, Utah 84121 up to ~ 0.5 Ma separating the Ojo Alamo Sand- lands University, Las Vegas, New Mexico 87701; The well-known Valles caldera hydrothermal stone from the base of the Nacimiento Formation and B. D. Allen, New Mexico Bureau of Geology outflow plume, which flows along the Jemez in the BDNZ area. Future work should focus on and Mineral Resources—Albuquerque Office, fault zone (JFZ) in Cañon de San Diego (CdSD) more accurately determining the age and refin- New Mexico Institute of Mining and Technol- in the southwest Jemez Mountains, New Mexi- ing the duration of the hiatus at the Ojo Alamo– ogy, Albuquerque, New Mexico 87106 co, possibly extends to the east of the currently Nacimiento formational contact. The Bull Gap quadrangle is located in the north- accepted limits. Recent geologic mapping on ern Tularosa Basin, south of Carrizozo and north the Cat Mesa and Jose fault zones (CMFZ and of Oscura, New Mexico. The topography is pri- JoFZ), 3–6 km east of the JFZ, has identified sev- EVALUATION OF CHEMICAL GEOTHER- marily low, rolling country with a long hogback eral Quaternary hydrothermal features. Also, a MOMETERS FOR ESTIMATING RESER- of Cretaceous strata trending north-south in the hot well with temperatures of 129°C at 829 m VOIR TEMPERATURES OF NEW MEXICO center of the map, and the Carrizozo lava flow depth (AET-4) located just east of the CMFZ GEOTHERMAL SYSTEMS, T. H. Schlossnagle, trending northeast-southwest across the quad- implies an eastward extension of the plume. F. M. Phillips, M. A. Person, and A. R. Campbell, rangle. Exposures of Permian and Cretaceous Indications of Quaternary hydrothermal activ- Department of Earth and Environmental Sci- strata are present in the center of the map area, ity include four generations of travertine deposi- ence, New Mexico Institute of Mining and and large tracts of modern alluvium and older tion, goethite/hematite/barite mineralization in Technology, 801 Leroy Place, Socorro, New fan deposits from the Sacramento Mountains fault zones and coating terrace gravels, and one Mexico 87801 cover bedrock geology to the east. The western sinter deposit on the JoFZ. The highest elevation New Mexico is endowed with relatively high one-third of the quadrangle lies to the north, and oldest travertine in the area rests on a ter- background heat flow and permeable, frac- south, and east of bedrock uplands, and surfi- race 190 m above the Jemez River. Stable isotope tured bedrock. This combination has given cial clastic sediments in this area are classified values for this travertine are δ13C of 5.18‰ PDB rise to numerous low-temperature geothermal as piedmont deposits with relative age designa- and δ18O of 23.74‰ SMOW. The other travertine systems throughout the state. Conventional tions based on inset relationships. The Carrizozo mounds lie on much lower terraces of around geothermometers consistently overestimate lava flow, ~ 5 ka in age, trends southwest to 40 m above the Jemez River and have an esti- temperatures for moderate- to low-temperature northeast across the center of the quadrangle. An mated age of around 155 ka. The sinter deposit

May 2012, Volume 34, Number 2 New Mexico Geology 57 intrudes into the JoFZ contact between Jurassic inland tetrapod ichnofauna. Such an interpreta- A JULIFORM MILLIPEDE FROM THE UPPER Entrada Sandstone and Tertiary Zia Formation tion coincides with paleogeographic reconstruc- PENNSYLVANIAN (VIRGILIAN) BURSUM and is indicative of very high temperature water. tions locating the study area during the Early FORMATION, CARRIZO ARROYO, CEN- The deposit is of an unknown age and appears Permian in an intramontane foreland basin (Taos TRAL NEW MEXICO, J. A. Spielmann and to be an exhumed vent. trough) of the ancestral Rocky Mountains at least S. G. Lucas, New Mexico Museum of Natural Recent detailed geologic mapping along the 160 km landward from the nearest marine shore- History and Science, 1801 Mountain Road NW, JFZ on the Pueblo of Jemez has identified three line. Given the rarity of fossil sites with Paleozoic Albuquerque, New Mexico 87104 inland (and upland) tetrapod communities, the generations of travertine deposition. The oldest Fossil millipedes are rare elements in the Paleo- Sangre de Cristo tetrapod ichnofauna is of global is at an elevation of 44 m above the river and has zoic assemblages of western North America and interest and deserves further research. an age of 233 ka. This travertine deposit rests on when found are often so poorly preserved that fine illite clay that was deposited across the JFZ. distinguishing diagnostic features proves impos- After the first travertine deposition, hematite- sible. The presence of a millipede at Carrizo Arroyo rich fluids cemented alluvial fan deposits, which REVISION OF REDONDASAURUS (ARCHO- (NMMNH locality 3433), a Virgilian locality in were then overlain by a 144 ka travertine deposit. SAURIA: PARASUCHIDAE) FROM THE the Red Tanks Member of the Bursum Formation The third travertine occurs near Salt Spring at an UPPER TRIASSIC (APACHEAN) OF THE with an extensive invertebrate fauna, was initially elevation of 9 m above the river and has an age AMERICAN SOUTHWEST, J. A. Spielmann described as a singular occurrence. However, a of 166 ka. Stable isotope data from these traver- and S. G. Lucas, New Mexico Museum of Natu- recent reexamination of the collected material from δ13 tines ranges from C values of 3.47‰–3.73‰ ral History and Science, 1801 Mountain Road Carrizo Arroyo has led to the discovery of five δ18 PDB and O values of 22.40‰–22.52‰ SMOW. NW, Albuquerque, New Mexico 87104 additional millipede specimens. These specimens These data are fairly consistent with published A recent restudy of Apachean-age phytosaurs, range in completeness from a dozen midbody U-series dates and stable isotope values from primarily from the Chinle Group of the Ameri- segments to a specimen that preserves the first 48 Soda Dam. The travertines on Jemez Pueblo are can Southwest, has allowed for the recognition segments of an individual, in part and counter- thought to have the same outflow plume origin of at least six new skulls of the Apachean Redon- part, including the individual’s head. All millipede as Soda Dam. U-series dates and stable isotope dasaurus, which when added to previously known specimens share consistent segment morphology data will be evaluated to determine if the out- cranial material, brings the total number of rec- and thus pertain to a single taxon. In contrast to flow plume is responsible for deposition of the ognized Redondasaurus skulls to ~ 12. With this modern millipedes, which are diagnosed at the CMFZ and JoFZ travertines. larger sample size, new taxonomically informative species level based on genital structure, fossil mil- characters have been recognized that further dis- lipedes are distinguished based on segment orna- EARLY PERMIAN TETRAPOD ICHNOFAU- tinguish Redondasaurus from closely related phy- mentation. The Carrizo millipede possesses the NA FROM THE SANGRE DE CRISTO FOR- tosaur taxa (e.g., Pseudopalatus, Nicrosaurus). The following diagnostic characters: a mid-segment MATION OF NORTH-CENTRAL NEW MEX- primary diagnostic character of Redondasaurus has ridge running dorsoventrally the height of the seg- ICO, S. Voigt, [email protected], S. G. traditionally been supratemporal fenestrae that ment that serves to separate the prozonite and the Lucas, and L. F. Rinehart, New Mexico Museum are hidden in dorsal view. However, now, with a metazonite; and no additional ornamentation of of Natural History, 1801 Mountain Road NW, greater sampling of skull characters, the following the segments. The Carrizo millipede is only one Albuquerque, New Mexico 87104 features are also recognized as diagnostic of Redon- of three examples of Paleozoic millipedes known dasaurus: reduced antorbital fenestrae; a prominent from western North America; others include mate- Early Permian tetrapod footprints from the San- pre-infratemporal shelf at the anteroventral mar- rial from the Upper Pennsylvanian to Lower Perm- gre de Cristo Formation of the Pecos River val- gin of the lateral temporal fenestra; septomaxillae ian limestones of Hamilton County, Kansas, and ley area in north-central New Mexico have been that wrap around the outer margin of the external the Upper Pennsylvanian Kinney brick quarry of known for more than two decades. Initial finds narial opening; a thickened orbital margin (distin- central New Mexico. Thus, these new millipede from 1989 were the first Paleozoic vertebrate guishing it from all other phytosaur except Cobur- specimens add significantly to our understanding tracks from New Mexico described in detail. gosuchus of Paleozoic millipedes and help to fill gaps in the Currently, the New Mexico Museum of Natu- ); and an inflated posterior nasal behind sparse fossil record of this group. ral History stores 167 footprint specimens from the external narial opening. Based on these newly seven localities in the upper part of the Sangre de recognized diagnostic characters Redondasaurus Cristo Formation in San Miguel County. A recent is demonstrably distinct from Pseudopalatus, and increase of material and knowledge necessitates arguments for their synonymy should be aban- revision of this ichnofauna. The assemblage com- doned. Further, we interpret Redondasaurus as prises tracks of Batrachichnus Woodworth, 1900, sexually dimorphic, with the males possessing an Limnopus Marsh, 1894, Ichniotherium Pohlig, 1892, overall more robust skull with a crest that extends Dimetropus Romer and Price, 1940, Tambachich- the length of the snout and females with a more nium Müller, 1954, cf. Hyloidichnus Gilmore, 1927, gracile skull that lacks a crest, analogous to the sex- and Dromopus, Marsh, 1894. They can be referred ual dimorphs recognized in Pseudopalatus. Given to temnopspondyl, diadectomorph, “pelycosaur,” the sexual dimorphism in Redondasaurus, the two captorhinid, and araeoscelid trackmakers. This named species should be synonymized, as the only assemblage represents a typical Early Permian difference between the two species were sexually red-bed tetrapod ichnofauna. Relatively large dimorphic characters of the crest. Thus, the holo- (pes length ~ 70 mm) imprints of cf. Hyloidichnus type of Redondasaurus gregorii is the female morph, referred to moradisaurine captorhinids may indi- and the holotype of R. bermani is the male morph. cate a late Early Permian (Artinskian–Kungurian; Given R. gregorii’s priority, R. bermani should be late Wolfcampian–Leonardian) age of the foot- treated as a junior subjective synonym. The newly New Mexico Geology thanks the New Mexi- print-bearing strata. The remarkable abundance recognized diagnostic characters of Redondasaurus co Geological Society Foundation for their of Ichniotherium (referred to diadectomorphs) and will hopefully allow additional specimens to be continuing financial support of the publica- Tambachichnium (referred to varanopid “pelyco- identified and increase the biostratigraphic utility tion of these abstracts. saurs”) suggests that the occurrence represents an of this taxon.

NMGS spring meeting Student winners for best presentation

Each year a panel of judges evaluates student oral and poster the western margin of the Rio Grande rift, central New Mexi- presentations. Scores are tallied from judging forms. This year co.” The award for best poster presentation was given to Sarah the award for best student talk was given to Jason Ricketts for Machin, for “The Beartooth–Mojado connection: using mid-Cre- his presentation “Calcite-filled fractures in travertine used to con- taceous sedimentary rocks to understand the tectonic history of strain the timing and orientation of Quaternary extension along southwest New Mexico.”

58 New Mexico Geology May 2012, Volume 34, Number 2