The Cretaceous System in Central Sierra County, New Mexico

Home , Carlile Shale, Dakota Formation, Fort McRae, Gray Mesa Formation, Inoceramus cuvieri, Love Ranch Formation

The Cretaceous System in central Sierra County, New Mexico

Spencer G. Lucas, New Mexico Museum of Natural History, Albuquerque, NM 87104, [email protected] W. John Nelson, Illinois State Geological Survey, Champaign, IL 61820, [email protected] Karl Krainer, Institute of Geology, Innsbruck University, Innsbruck, A-6020 Austria, [email protected] Scott D. Elrick, Illinois State Geological Survey, Champaign, IL 61820, [email protected]

Abstract (part of the Dakota Formation, Campana (Fig. 1). This is the most extensive outcrop Member of the Tres Hermanos Formation, area of Cretaceous rocks in southern New Upper Cretaceous sedimentary rocks are Flying Eagle Canyon Formation, Ash Canyon Mexico, and the exposed Cretaceous sec- Formation, and the entire McRae Group). A exposed in central Sierra County, southern tion is very thick, at about 2.5 km. First comprehensive understanding of the Cretaceous New Mexico, in the Fra Cristobal Mountains, recognized in 1860, these Cretaceous Caballo Mountains and in the topographically strata in Sierra County allows a more detailed interpretation of local geologic events in the context strata have been the subject of diverse, but low Cutter sag between the two ranges. The ~2.5 generally restricted, studies for more than km thick Cretaceous section is assigned to the of broad, transgressive-regressive (T-R) cycles of 150 years. (ascending order) Dakota Formation (locally deposition in the Western Interior Seaway, and includes the Oak Canyon [?] and Paguate also in terms of Laramide orogenic history: Our goal here is to present the [?] members), lower interval of the Mancos (1) T1 transgression of the seaway during first comprehensive study of the Cre- Formation (Graneros, Greenhorn, and Carlile middle-late Cenomanian time resulting taceous sedimentary rocks in central members), Tres Hermanos Formation (Atarque, in deposition of the Dakota Formation, Sierra County—their lithostratigraphy, Campana, and Fite Ranch members), D-Cross Graneros Member of the Mancos Formation and paleontology and age, sedimentary Greenhorn Member of the Mancos; (2) Turonian Member of the Mancos Formation, Gallup petrography and depositional history. Our R1 regression with deposition of the Carlile Formation, Flying Eagle Canyon Formation, study entails revisions to the Cretaceous Ash Canyon Formation, and the McRae Group, Member of the Mancos Formation and the Atarque and Campana members of the Tres lithostratigraphic nomenclature used in consisting of the José Creek, Hall Lake, and Double Sierra County and provides new precision Canyon formations. The name Tokay Tongue Hermanos Formation; (3) late Turonian T2 to correlation of parts of the section. Our of the Mancos Formation is abandoned as an transgression marked by deposition of the unnecessary term that reduces lithostratigraphic Fite Ranch Member of the Tres Hermanos analysis thus allows the Cretaceous strata precision. The new name Campana Member Formation and lower D-Cross Member of the of Sierra County to be integrated further of the Tres Hermanos Formation is proposed Mancos Formation; (4) R2 regression during late into a broader understanding of Cretaceous to replace the preoccupied (duplicate) name, Turonian-early Coniacian time, with deposition geological history in New Mexico. Carthage Member. The terms Mesaverde of the upper sandy part of the D-Cross Member, Some of the data collected in this study the Gallup Formation, and the lower part of the Formation (Group) and Crevasse Canyon are presented in appendices to this report, Flying Eagle Canyon Formation; (5) no clear Formation are no longer applied to part of the which are available as a separate, down- Cretaceous section in Sierra County. Instead, record of the T3, R3 or T4 events in Sierra County, but the Flying Eagle Canyon Formation loadable file. These data include graphic these strata are the Flying Eagle Canyon depictions of measured stratigraphic sec- Formation (new name) and redefined Ash likely encompasses the time from the last phase tions, representative photographs of thin Canyon Formation. The very thick McRae of R2 through T4 (Coniacian–Santonian); (6) Formation is raised in rank to the McRae R4 regression of early Campanian age and the sections used in petrographic analyses, Group, and its constituent members are raised onset of the Laramide orogeny, when deposition photographs of selected fossils, and a geo- to formations. The Double Canyon Formation of the Ash Canyon Formation took place; (7) logic map that shows the distribution of is a new lithostratigraphic unit comprising the the first significant influx of volcanic detritus at one of the new stratigraphic units discussed upper part of the McRae Group. Ammonite and the base of the McRae Group derived from the herein. Previous studies of the Cretaceous late Campanian-early Maastrichtian (~70–75 inoceramid bivalve biostratigraphy indicates strata in Sierra County are reviewed in the Ma) Copper Flat igneous complex; (8) onset of that the lower interval of the Mancos Formation appendices, which also include a summary is of middle Cenomanian-early Turonian age, Hall Lake Formation deposition during the late Maastrichtian (~66–68 Ma); (9) deposition of the of subsurface data in tabulated form and the Atarque Member of the Tres Hermanos a geologic cross section that incorporates Formation is early Turonian, the D-Cross bulk of the Hall Lake Formation and the Double those data. References in the main text to Member of the Mancos Formation is middle Canyon Formation, possibly extending into the Turonian, and the Gallup Formation is late Paleocene; and (10), the Love Ranch Formation items in the appendix are preceded with Turonian. Vertebrate biostratigraphy indicates of likely Eocene age representing the final pulse the letter “A” (e.g., Table A2.1). that the lower part of the Hall Lake Formation is of the Laramide orogeny in Sierra County. Lancian (late Maastrichtian) in age. Depositional Study area, methods, environments of the Cretaceous strata in Sierra Introduction abbreviations, and conventions County are both marine and nonmarine. They range from offshore marine (lower interval and Cretaceous sedimentary rocks are exposed The Cretaceous strata of central Sierra D-Cross Member of the Mancos Formation), County are exposed from the northern tip to shoreline deposition of various types (part in central Sierra County, southern New of the Dakota Formation, the Atarque and Mexico, in and around parts of the of the Fra Cristobal Mountains (just into Fite Ranch members of the Tres Hermanos Fra Cristobal and Caballo Mountains, as Socorro County) to the northern Caballo Formation, and the Gallup Formation), to non- well as in the lowlands between the two Mountains and its eastern periphery (Fig. marine fluvial channel and floodplain deposits mountain ranges, the structural Cutter sag 1). These strata extend eastward under

Spring 2019, Volume 41, Number 1 3 New Mexico Geology the Jornada del Muerto basin and west- ward under the Rio Grande rift. Place Tv QTs names used in the text are those on the Tv K relevant United States Geological Sur- Qb vey topographic quadrangle maps. The 33°30´N Qs horizontal datum for coordinates reported Socorro Sierra X herein is NAD83 (UTM meters, zone 13). P The research reported here is based primarily on fieldwork undertaken during Tv 2013–2017, though some paleontological X data were collected as early as the 1980s. Tv This fieldwork was largely part of an effort SOC QTs to map the geology of the Fra Cristobal 33°24´N P QTs Mountains. Understanding the Creta- Qs ceous strata exposed in the Fra Cristobals Tv Fra Cristobal Mtns. QTs necessitated fieldwork to better under- Tv stand the Cretaceous strata exposed to the south, in the Cutter sag and in the northern

Elephant Butte Tv

Caballo Mountains. Data and interpreta- Reservoir P Qs Tv tions from oil-test boreholes—archived 33°18´N at the New Mexico Bureau of Geology and Mineral Resources (NMBGMR) 142 (Socorro)—were examined in order to QTs obtain additional estimates of thicknesses of some of the Cretaceous units in the Tv area, and are summarized herein. Data collection included: mapping 51 P Tim in the Fra Cristobal Mountains and the 33°12´N Pa area immediately to the south and south- SOC K Tv west of the range; measuring numerous

D J o r n a d a d e l M u e r t o stratigraphic sections using a 1.5 m OC Tv X staff and Brunton pocket transit (Fig. T or C Tv 2); collecting numerous rock samples for petrographic analysis; and collecting QTs Tv Tv invertebrate and vertebrate fossils, primar- K Qs ily for biostratigraphic analysis. All fossils 33°06´N collected are part of the collection of the X New Mexico Museum of Natural History QTs and Science (NMMNH) in Albuquerque 25 Tim and bear NMMNH locality and catalog Pa numbers. Lithofacies codes assigned to QTs nonmarine sediments (e.g., Gt, St, etc.) are P Py K 10 km from Miall (1996, 2010). In petrographic

33°00´N Caballo analysis, sandstone composition was Qs Quaternary sediments Caballo Reservoir determined microscopically by identifying Qb Quaternary basalt Qs QTs Mtns. the different grain types at 250 equally X QTs Tertiary - Quaternary sediments spaced points across each thin section Tv TertiaryTv volcanics analyzed (Tucker, 1988), using thin section SOC K K Cretaceous P Pa QTs Py Permian (Yeso Group, San Andres Fm.) photographs and the program JMicro- Pa Permian (Abo Formation) Vision. In the petrographic analysis, Q D P Permian Tv PIP Permian and Pennsylvanian, undivided includes monocrystalline, polycrystalline, 32°54´N QTs and microcrystalline quartz, and chert. IP Pennslyvanian Qs X D Devonian Py Sandstones were classified using the scheme QTs SOC Cambrian - Ordovician - Silurian proposed by Pettijohn et al. (1987). Tv OC Cambrian - Ordovician N P X Proterozoic crystalline rocks As a convention in the lithostrati- PP Tv Tv graphic nomenclature used here, all units QTs P Tim Tertiary dikes Major faults are referred to as a group, formation, or 107°20´W 107°10´W 107°00´W member. We do not use lithologic modifiers (e.g., sandstone, shale) or the term FIGURE 1. Geologic map (after NMBGMR, 2003) showing location of Cretaceous outcrops in tongue to refer to any of the formal Cre- central Sierra County, New Mexico. taceous lithostratigraphic units discussed here, even though those terms have been

Spring 2019, Volume 41, Number 1 4 New Mexico Geology San Mateo Mtns.

Fra Cristobal North NFC Conglomerate

Fra Cristobal Mtns N Victorio 2 Victorio 1 Measured sections Jornada Drill holes 10 km del

Walnut Canyon Walnut Canyon Log Muerto Elephant Flying Eagle Canyon Butte 1 McRae Forest Flying Eagle Atarque Fossil Forest Reynolds Canyon Drew-Mathews

Cottonwood Canyon Double Canyon Sierra State Kettle Top A-1 Mims Elephant Butte 2 Type José Creek Leeman Federal Engle McRae Canyon Mud Springs Mountain Jornada 3

Beard Federal Mescal Canyon Sierra 3 Jornada 1 Caballo Mtns

FIGURE 2. Topographic map of part of Sierra County, New Mexico, showing locations of stratigraphic sections measured for this investigation (also see Table A2.1). used by others. The lithologic modifiers Previous studies Previous studies of Cretaceous strata in are generally inaccurate—the Mancos Sierra County are reviewed in Appendix Shale, for example, includes lithotypes The Cretaceous strata of Sierra County 1, and the development of stratigraphic other than shale. And, the units referred have been long studied since shortly after nomenclature applied to these rocks is to as “tongues” either do not have that Mexico ceded the territory that is now summarized in Figure 3. geometry (e.g., the so-called tongues of the New Mexico to the United States in 1848. Dakota Formation) or their intertongued Accounts of these investigations are found Dakota Formation relationship to other units is inferential in a wide array of government reports, and not demonstrable in Sierra County. articles in scientific journals, and unpub- Lithostratigraphy Therefore, we regard our convention in lished theses and dissertations. From these lithostratigraphic nomenclature as simpler studies, an understanding of diverse aspects Introduced by Meek and Hayden (1861), and more accurate than other usages. of the Cretaceous section has emerged. Dakota is one of the most widely used

Spring 2019, Volume 41, Number 1 5 New Mexico Geology stratigraphic names in North Amer- complete section in Mescal Canyon (Figs. contains cobble-sized clasts of partially ica. Keyes (1905a) and Harley (1934) 4D–F, 5B, A3.3). Various thicknesses of silicified, gray San Andres limestone and extended the term “Dakota sandstone” the Dakota Formation in Sierra County rounded pebbles of chert, ironstone, and into Sierra County, and all subsequent have been reported, including 24 and jasper. Medium to thick cross-bedding in authors have accepted that usage. The 27 m (Melvin, 1963), 49 m (Doyle, 1951), the lower part gives way to planar and Dakota Formation is the stratigraphi- 75 m (Kelley and Silver, 1952), and 2 to wavy lamination and thin bedding in the cally lowest Cretaceous unit in Sierra 106 m (Bauer, 1989; Seager and Mack, upper part. The contact with the overlying County, cropping out in the southern Fra 2003). The sections we measured docu- Mancos Formation is gradational through Cristobal Mountains, at Mescal Canyon ment Dakota Formation thicknesses of an interval several meters thick. Good and along the eastern front of the Caballo 24 to 39 m. Data from 15 oil-test holes exposures of the transition zone may be Mountains. At all of its outcrops, the east and west of the Fra Cristobal Range viewed in the Reynolds Canyon section Dakota rests disconformably on the lower record a thickness range of 18 to 73 m (Fig. A3.2) and along the southwest-trend- Permian San Andres Formation and is (Table A2.2). ing arroyo 0.8 km northeast of Bert overlain by the Mancos Formation. Strata In the southern part of the Fra Cook Well in the western headwaters of beneath the Dakota along the eastern front Cristobal Range, the Dakota is an Reynolds Canyon (Fig. A4.1). of the Caballo Mountains were assigned to upward-fining succession of nearly At Flying Eagle Canyon, the Dakota the Yeso Formation by Seager and Mack pure quartz sandstone. Color, weather- Formation is 24 m thick and is composed (2003), but other workers interpreted ing aspect, and bedding style distinguish almost entirely of quartzose sandstone these underlying strata as San Andres the Dakota from any of the Paleozoic and silica-pebble conglomerate (Figs. Formation (Kelley and Silver, 1952; Lucas sandstones, even in small, fault-bounded 4A–C, A3.1). Trough cross-bedding is and Krainer, 2012). exposures. Freshly broken sandstone is the prevalent bedform, and a few beds We measured three stratigraphic sec- nearly white, whereas weathered surfaces display ripple lamination or tabular tions of the Dakota Formation in Sierra are stained pink, magenta, and orange. bedding. The lowest bed of the Dakota County: (1) a complete section of the Grain size decreases from medium to is a trough cross-bedded conglomerate unit at Flying Eagle Canyon (Figs. 4A–C, coarse near the base to very fine near containing chert and other siliceous 5A, A3.1); (2) an incomplete section at the top. Sand grains are rounded and pebbles. The conglomerate has a scoured Reynolds Canyon (Fig. A3.2); and (3) a well-sorted. Conglomerate at the base base with local stratigraphic relief of up to

Hook et al. Kelley and Silver Bushnell this Harley (1934) Wallin (1983) (2012), Mack et (1952) (1955a, b) al. (2016) paper Double Canyon Formation Hall Lake Member McRae McRae not not Hall Lake Formation studied Formation

studied Group

Formation McRae Jose Creek José Creek Member Formation Mesaverde Ash Canyon Ash Canyon Formation Member Member Ash Canyon Formation barren Crevasse Canyon member Formation Formation coal-bearing Flying Eagle

Crevasse Canyon member Canyon Formation Mesaverde Mesaverde Formation Mesaverde Group Formation Gallup Sandstone Gallup Sandstone Gallup Formation main body D-Cross Tongue D-Cross Tongue D-Cross Member (Mancos Shale) (Mancos Shale) (Mancos Formation)

Fite Ranch Fite Ranch Sandstone Member Member Carthage Member Carthage Member Campana Member

Mancos Formation Atarque Sandstone Formation Atarque Sandstone Formation

Tres Hermanos Tres Hermanos Tres Hermanos Tres Atarque Member Shale Member Member Tokay Tongue Carlile Member Mancos Mancos Mancos (Mancos Shale Shale Shale Bridge Creek Beds Greenhorn Member

Shale) Mancos Formation Graneros Member

Paguate Member? Dakota Dakota Dakota Dakota Dakota Oak Canyon Member? Sandstone sandstone/conglomerate

Sandstone Group Group Sandstone Dakota

Formation member FIGURE 3. Development of Cretaceous lithostratigraphic nomenclature in Sierra County, New Mexico.

Spring 2019, Volume 41, Number 1 6 New Mexico Geology 2 m on top of the San Andres Formation, of the Dakota Formation strata exposed intervals: basal sandstone, medial shale, and is overlain by trough cross-bedded in Flying Eagle Canyon. However, a signif- and upper sandstone. The basal sandstone sandstone with lenses of conglomerate icant difference is that the uppermost bed interval (Fig. A3.3, units 2–5) is 7.5 m containing chert pebbles. This unit is of the Dakota Formation is bioturbated thick and composed of trough cross-bed- overlain by fine-grained, ripple-laminated at Reynolds Canyon, whereas it is not at ded and horizontally laminated sandstone sandstone, horizontally laminated sand- Flying Eagle Canyon. with much oxidized fossil plant debris stone, trough cross-bedded sandstone, and At Mescal Canyon (Figs. 4D–F, 5B, (Fig. 4D). The medial sandy shale interval massive sandstone. The top sandstone bed A3.3), the Dakota Formation is thicker is an ~27 m thick succession dominated of the Dakota Formation is conformably (~39 m thick) and has a very different by sandy shale and muddy, cross-bedded overlain by greenish-gray shale at the base stratigraphic architecture than in the or bioturbated, thin sandstone beds and of the Mancos Formation. southern Fra Cristobal Mountains, and lenses (mostly <0.2 m, rarely up to about 1 In Reynolds Canyon, only 7.6 m of this stratigraphic architecture is present m) and scattered carbonaceous debris. The the upper part of the Dakota Formation at all of its outcrops in the Caballo uppermost sandstone interval (Fig. A3.3, crops out above a fault (Fig. A3.2). These Mountains (Seager, 1995b, c; Seager and units 14–16) is ~5 m thick and composed strata are very similar to the upper part Mack, 2003). It can be divided into three of trough cross-bedded or horizontally

A B

C D Paguate Member?

Oak Canyon Member?

E F FIGURE 4. Photographs of selected outcrops of the Dakota Formation in Sierra County, New Mexico. A–C, Flying Eagle Canyon section. A, Overview of upper part of Dakota Formation. B, Cross-bedded sandstone. C, Silica-pebble (e.g., quartzite, chert) conglomerate. D–F, Mescal Canyon A section. D, Cross-bedded sandstone near base. E, Overview of upper part of section showing shaley interval of Oak Canyon Member(?) overlain by sandstone beds of Paguate Member(?). F, Crustacean burrows (Ophiomorpha) in Paguate Member(?).

Spring 2019, Volume 41, Number 1 7 New Mexico Geology laminated sandstone with extensive Mexico the White Rock Mesa Member. of the Dakota section in Mescal Canyon is bioturbation (primarily the well-known This sandstone-dominated unit has coal similar to the Cubero Member, but more crustacean burrows Ophiomorpha [Fig. beds and other carbonaceous strata, unlike closely resembles the Paguate Member 4F] and Thalassinoides). The intensity the Dakota “main body” in Sierra County. of the Dakota Formation to the north. of bioturbation mostly varies from 10 Therefore, we do not use the name White We note that at many locations to 25% using the bioturbation index Rock Mesa Member for these Dakota in northern New Mexico, not all of the of Miller and Smail (1997), and has an strata in Sierra County and instead refer to sandstone members of the Dakota Formation ichnofabric of 2–3 (cf. Droser and Bottjer, them informally as the sandstone/conglom- are present (e.g., Landis et al., 1973; 1986). A few beds, however, are very erate member of the Dakota Formation Lucas et al., 1998b). This lack of conti- intensively bioturbated and have an ich- (Figs. 3, A3.3). nuity is not consistent with early ideas nofabric of 5. The bioturbated top of this The Dakota Formation section at (e.g., Peterson and Kirk, 1977; Owen and sandstone interval is very coarsely Mescal Canyon resembles part of the Sparks, 1989) that the sandstone members grained, locally pebbly, and is over- intertongued Dakota–Mancos succession of the Dakota are regressive shoreline lain by gray shale at the base of the in northern New Mexico (e.g., Landis et al., deposits and therefore seaward tongues Mancos Formation. 1973; Lucas et al., 1998b; Head and Owen, of a landward Dakota lithosome. Instead, The Dakota Formation strata at Flying 2005). Thus, most of the Dakota Formation the Dakota sandstone members more Eagle and Reynolds canyons are nonma- section at Mescal Canyon (other than the likely represent offshore sand bodies of rine sandstone and conglomerate (see upper sandstone interval) closely resembles discontinuous ridges, bars, and shoals that below). Such strata are typically referred strata of the Oak Canyon Member to accumulated during shoreline stillstand in to as the “main body” of the Dakota the north—gray sandy shale with a a generally transgressive system. During Formation (e. g., Landis et al., 1973; Hook few, intercalated thin sandstone beds those stillstands, sand sourced from Lar- and Cobban, 2015). Owen and Owen and scattered carbonaceous debris. The amidia to the west was spread across a (2005) renamed the “main body” of the cross-bedded, laminated, and extensively broad and shallow shelf (Molenaar, 1983; Dakota Formation in northwestern New bioturbated sandstone interval at the top Head and Owen, 2005). This model of

Tres Hermanos Formation

Mancos Formation

Dakota Formation

A B Fite Ranch Member

Campana Member

Atarque Member

Carlile Member, Mancos Formation

C D FIGURE 5. Photographs of selected outcrops of the Dakota Formation, lower interval of the Mancos Formation and Tres Hermanos Formation in Sierra County. A, Overview of lower part of Flying Eagle Canyon section looking east. Lower interval of Mancos Formation is slope-forming shale unit below Tres Hermanos Formation. B, Upper, bioturbated sandstone interval of Dakota Formation at Mescal Canyon here assigned to the Paguate Member(?). C, View of light-colored bentonite beds in Graneros Member of Mancos Formation at Mescal Canyon. D, Overview of part of Mescal Canyon A section looking approximately north, showing all three members of the Tres Hermanos Formation.

Spring 2019, Volume 41, Number 1 8 New Mexico Geology Dakota deposition needs further analysis, the lower, nonmarine strata of the Dakota as thin, cross-bedded, channel-fill sandstones but it does explain why the sandstone section, as best seen at Flying Eagle and thick estuarine deposits. The upper members of the Dakota Formation are not Canyon, could be of Early Cretaceous sandstone unit with abundant burrows is continuous across their depositional basin. age (cf. Seager, 1981; Lucas and Estep, definitely marine, representing nearshore Middle Cenomanian fossils of the 1998), though no data support such an (shoreface) deposits. According to Seager Acanthoceras amphibolum Morrow age assignment. and Mack (2003; also see Bauer, 1989), ammonite zone are present just above the the lower and middle parts of the Dakota Dakota Formation at Reynolds Canyon Sedimentary petrography Formation at Mescal Canyon are fluvial and at Mescal Canyon (Hook et al., 2012; deposits divided into channel and floodplain also see below), so correlation to the Oak Sandstone of the Dakota Formation in facies with eastward and northeastward Canyon, Cubero and Paguate members Sierra County (Fig. A5.1A–B) is mostly paleoflow directions. Bioturbated shale and of the Dakota Formation is not contra- medium grained and well-sorted, and sandstone (including characteristic marine dicted by biostratigraphy (the Cubero and locally contains a few larger clasts with trace fossils, such as Ophiomorpha) near Paguate are in the zone of A. amphibolum). diameters up to 5 mm, resulting in mod- the top of the middle part indicate a marine The possibility that the upper sandstone erate to poor sorting. Most of the detrital depositional setting, and the uppermost interval of the Dakota Formation at grains are subrounded, but some grains shale bed is interpreted as lagoonal or estu- Mescal Canyon is the Cubero Member are rounded (Fig. A5.1A–B). Microscopic arine deposits. The overlying sandstones of cannot be discounted, though the bed- study confirms the field observation that the upper part of the Dakota Formation forms and intensity of bioturbation sandstone of the Dakota is quartz arenite. display ripple lamination and bioturbation, are more characteristic of the Paguate Monocrystalline quartz (including a few and have been interpreted as tidal-flat Member (cf. Lucas et al., 1998b). The pos- porphyry quartz grains; porphyry quartz deposits (Seager and Mack 2003), but are sible presence of an unconformity at the is volcanic quartz derived from rhyolite) more likely shelf sandstones representing base of the upper sandstone interval (Mack is the dominant grain type. Polycrystalline shoals and offshore bars (see above). The et al., 2016) and of the “x” bentonite just quartz is present in small amounts. Chert uppermost very coarse to pebbly sandstone above the sandstone interval (see below) grains are a common constituent. is interpreted as a lag deposit representing also supports a Paguate correlation. The larger grains are different types a ravinement surface (transgressive lag) Molenaar (1983) tentatively ident- of microcrystalline quartz (chert), rarely (Seager and Mack, 2003). ified the upper sandstone interval displaying spherulitic texture, which At Flying Eagle Canyon and Reynolds of the Dakota Formation in Mescal indicates that these grains are derived Canyon, the Dakota Formation is thinner Canyon as the Twowells Member, from acidic volcanic rocks (Fig. A5.1A–B). and coarser grained; mudstone is absent. but that unit is of late Cenomanian Rarely, patches of clay minerals are The lower part is composed of fine-grained age (ammonite zone of Calycoceras present that most likely represent altered conglomerate and sandstone, likely rep- canitaurinum [Haas]), so it is too young detrital feldspar grains (Fig. A5.1B). The resenting fluvial channel fills. The middle to correlate to the sandstone interval at detrital grains are cemented by quartz that part is composed of fine-grained sandstone the top of the Dakota in Mescal Canyon. is present as well-developed authigenic displaying horizontal lamination, ripple Tentative identification of the Oak Can- overgrowths (Fig. A5.1A–B). Locally, lamination and trough cross-bedding, yon and Paguate members of the Dakota some blocky calcite cement is present. All and the upper part is composed of trough Formation in Mescal Canyon (Fig. A3.3) samples plot into the field of quartz arenite cross-bedded sandstone, all likely repre- thus is based primarily on stratigraphic (classification schemes of McBride, 1963, senting fluvial deposits. position and lithologic resemblance, but and Pettijohn et al., 1987), and the average not a correlation supported by detailed composition is Q99.7F0L0.3 (see discussion of biostratigraphic data. petrofacies below). Lower interval of Mancos Formation–Graneros, Paleontology and age Depositional environments Greenhorn, and Carlile members

Other than the trace fossils Ophiomorpha The Dakota Formation is one of the most Lithostratigraphy and Thalassinoides (Fig. 4F), we observed widespread lithologic units of the Western no identifiable fossils in the Dakota Interior Seaway. It records the initial trans- Cross and Purington (1899) gave the Formation in Sierra County. Seager and gression of the Cretaceous seaway across name Mancos Shale to a thick succes- Mack (2003, fig. 38) reported that fossil much of New Mexico and thus represents sion, dominantly of shale, overlying the oysters are present in the upper part of the different types of nearshore marine sedi- Dakota Formation in the Mancos Valley medial shale unit of the Dakota Formation mentation. It marks the beginning of the near the town of Mancos in southwest- at Mescal Canyon. T1 transgression of Weimer (1960; also see ern Colorado. Subsequently, the name As already noted, bivalve and ammo- Molenaar, 1983), which reflects a major Mancos was extended through large areas nite fossils from the lowermost Mancos tectonic reorganization of the Cretaceous of western Colorado, eastern Utah, north- Formation at Reynolds Canyon and marine basins of the American Southwest eastern Arizona, and New Mexico. The Mescal Canyon are of middle Ceno- (e. g., Mack, 1987). Mancos exhibits large-scale intertonguing manian age (Hook et al., 2012), so As already discussed, the Dakota relationships with sandstone units that this sets a minimum age for the Dakota Formation can be divided into three units carry a wide variety of names. Formation strata. It seems most likely that at Mescal Canyon. We interpret the lower The Mancos Formation forms two all of the Dakota Formation strata in Sierra sandstone unit as composed of fluvial intervals of the Cretaceous section in County are of Cenomanian age. However, channel-fill sandstones, and the middle part Sierra County, a lower interval between the

Spring 2019, Volume 41, Number 1 9 New Mexico Geology Dakota and Tres Hermanos formations, three units (ascending): Graneros Shale, Formation near Carthage in Socorro and an upper interval between the Tres Greenhorn Limestone, and Carlile Shale, County (Hook and Cobban, 2015). The Hermanos and Gallup formations. The and those names have long been used “main body” of the Dakota in this area upper interval has consistently been termed in northern New Mexico (e.g., Rankin, (cf. Hook, 1983; Hook and Cobban, 2015) the D-Cross Tongue (Molenaar, 1983; Sea- 1944; Pike, 1947; Kauffman et al., 1969; is very similar to what we are calling the ger and Mack, 2003; Hook et al., 2012), Coates and Kauffman, 1973; Lucas et al., sandstone/conglomerate member of the and we refer to it as the D-Cross Member 1987). Given that the lower interval of Dakota in Sierra County. However, in the (see below), although some early workers the Mancos Formation in Sierra County is Caballo Mountains, additional Dakota (e.g., Lee, 1907b; Darton, 1928; Harley, readily divided into Graneros, Greenhorn, strata above this member show marine 1934) did not recognize an upper interval and Carlile lithosomes (Figs. A3.1–A3.3), influence and are likely equivalent to part of the Mancos in Sierra County (Fig. 3). those names are used here. In addition, of the intertongued Dakota–Mancos suc- However, more than one name has been in Socorro County, where the type sec- cession to the north (see earlier discussion). applied to the lower interval of the Mancos tion of the Tokay Tongue is located, the Thus, use of the name Tokay Tongue in Formation, including Rio Salado Tongue lower Mancos can be readily divided into the Caballo Mountains redefines the base and Tokay Tongue. This interval includes Graneros, Greenhorn and Carlile intervals, of that unit upward, so it is significantly strata equivalent to and lithologically as was first done by Rankin (1944, p. 21–22, higher than at the type locality. similar to the Graneros Shale, Greenhorn fig. 6) (Fig. 6). Hook and Cobban (1981; also see Limestone, and Carlile Shale of northern There is another problem with Cobban et al., 1989) also applied the old New Mexico (Fig. 6), so we apply these application of the term Tokay Tongue name Colorado Formation (or Shale) names as members to the lower interval of in Sierra County. As originally defined, of White (1878) to essentially the same the Mancos Formation in Sierra County. the base of the Tokay Tongue rests stratigraphic interval as the Tokay Tongue Hook et al. (1983) defined the Rio on the “main body” of the Dakota in southwestern New Mexico, so Tokay is Salado Tongue of the Mancos Shale in west-central New Mexico as the shale-dominated stratigraphic unit between the West-central Northeastern Southern New Mexico New Mexico New Mexico Twowells Tongue of the Dakota Sandstone Juana Lopez Juana Lopez Tres Hermanos (below) and the Tres Hermanos Formation Member Member Formation or equivalent strata of the Juana Lopez Member of the Mancos Formation (above) (Fig. 6). Hook and Cobban (2015, p. 27) coined the name Tokay Tongue in Socorro Carlile County to refer to “that portion of the Rio Shale Mancos Shale between the undifferentiated Salado Tongue or main body of the Dakota Sandstone and the Tres Hermanos Formation (or offshore equivalent)” in southern New Greenhorn Mexico (Fig. 6). Rio Salado is a useful term Member where the Twowells Member of the Dakota Twowells Sandstone is present and can be identified Sandstone with certainty, though the term Graneros Tongue "Tokay Shale Member of the Mancos Shale has Tongue" or Whitewater Arroyo "Colorado been used in a restricted sense to refer to Shale Tongue Formation" the same interval in the southern San Juan "x" bentonite Paguate Basin (Head and Owen, 2005; Owen et Sandstone Tongue Bridge Creek al., 2007), a usage we do not endorse. A Graneros Beds broader use of the term Rio Salado Tongue, Clay Mesa Shale to refer to the entire lower interval of the Tongue Mancos Formation in Sierra County and southward (Lucas and Estep, 1998; Lucas Cubero "x" bentonite Sandstone et al., 2000; Seager and Mack, 2003) was Tongue Thatcher Limestone rejected by Hook and Cobban (2015), and Member we also abandon that usage. Tokay Tongue, however, is simply Oak "x" bentonite Canyon a synonym of the unit that Meek and Romeroville Dakota Sandstone Member Hayden (1861) long ago named the “Fort Sandstone ("main body") note: Oak Canyon, Cubero, Paguate (Dakota Group) Benton group” (more commonly called and Twowells are members of Dakota Sandstone; Clay Mesa, Whitewater Arroyo Benton Group or Benton Shale: Wilmarth, and Rio Salado are members of the Mancos Shale 1928; Cobban and Reeside, 1952) and that has long been abandoned in favor of a more detailed lithostratigraphic termi- FIGURE 6. Regional stratigraphy of the Dakota–Mancos interval in New Mexico. Left column nology. In southeastern Colorado, Gilbert based on Owen et al. (2007); middle column based on Kauffman et al. (1969); and column on right (1896) divided the Benton Group into represents Socorro County and is the nomenclature of Hook and Cobban (2015).

Spring 2019, Volume 41, Number 1 10 New Mexico Geology also a synonym of Colorado as used by stratigraphic interval for which three Member of the Mancos Formation. This Hook and Cobban, 1981 (though note names already exist and were first applied stratigraphic interval correlates to part that Cobban et al. [2008] did abandon more than 70 years ago (Fig. 6). Therefore, of the Bridge Creek Member of the the term Colorado Formation, following we recommend the name Tokay Tongue Greenhorn Formation on the High Plains, Molenaar [1983] and Lucas et al. [2000]). be abandoned. but is not the same unit lithologically or Thus, the Tokay Tongue is both a syn- We also abandon the term “Bridge in terms of its lithostratigraphic extent (cf. onym of unit(s) named long ago, and its Creek beds” as used by Hook and Cobban Hattin, 1975, 1987). use embodies a reduction in stratigraphic (2015; also see Hook et al., 2012) to refer The outcrop distribution of the lower precision by applying one name to a to the interval we term the Greenhorn interval of the Mancos Formation in Sierra

A B

C D

Atarque Member

Carlile Member

E F

FIGURE 7. Photographs of selected outcrops of the lower interval of the Mancos Formation. A, Mescal Canyon A section, thinly interbedded sandstone and shale/siltstone of the Graneros Member of the Mancos Formation. B, Limestone bed of Greenhorn Member of Mancos Formation in Mescal Canyon A section. C, Limestone of the Greenhorn Member of the Mancos Formation in Flying Eagle Canyon section. D, Shale slope of Carlile Member of Mancos Formation in Flying Eagle Canyon section. E, Cyclically bedded shale of Carlile Member in Mescal Canyon A section. F, Upper part of Carlile Member just below cuesta formed by Atarque Member of Tres Hermanos Formation in Mescal Canyon A section.

Spring 2019, Volume 41, Number 1 11 New Mexico Geology County corresponds to that of the under- that of the Graneros Member, with inter- Member is ~13 m thick. The Carlile lying Dakota Formation. Naturally, the beds and lenses of limestone ranging from Member of the Mancos Formation is Mancos is less resistant to erosion than the a few cm to about 30 cm thick. The thick- dominantly black shale with thin interca- sandstone-dominated Dakota (below) and est limestone beds lie about 20 m above lations of hummocky, cross-bedded sand- Tres Hermanos (above), but many excel- the Mancos base. A molluscan fauna, stone (one bed, 0.6 m thick), horizontally lent exposures can be found along ravines chiefly inoceramid bivalves, is present (Fig. laminated sandstone (two beds, up to 3 m and canyons flowing to the Rio Grande A6.1D–E). Limestone beds are dark gray, thick) and many thin sandstone beds (<0.2 (e.g., Figs. 5A, D, 7). The lower interval of weathering light gray and yellowish gray, m thick, in the upper half). Black shale in the Mancos Formation crops out in the and micritic. The thicker limestone beds the upper part (174–195 m) contains lime- southern Fra Cristobal Mountains, at Mescal tend to be concretionary. The upper part stone nodules (concretions). Canyon in the northern Caballo Mountains, of the lower Mancos (Carlile) is silty shale Seager and Mack (2003) drew and along the eastern base of the Caballo with siltstone becoming increasingly preva- attention to 5 bentonite beds. These beds Mountains. Although relief is lower along the lent upward. Siltstone laminae are medium are 2–4 cm thick and conspicuous in a 1.2 eastern flank of the Caballo Mountains, the gray, calcareous, and planar to wavy. The m thick interval of the Graneros Member Mancos is exposed well enough to be read- lower Mancos generally lacks the large (Fig. 5C) to the east of our measured ily mappable on the ground and from aerial septarian concretions that are conspicuous section in Mescal Canyon (at UTM images. The lower interval of the Mancos in the younger D-Cross Member of the 293695E, 3668087N). Most important Formation is a shale-dominated unit with a Mancos. The contact with the overlying is possible identification of one of these relatively thin, limestone and shale interval Tres Hermanos Formation is gradational bentonite beds near the base of the in its lower part, the Greenhorn Member. through an interval several meters thick, Graneros Member as the “x” bentonite We measured three sections of the lower in which sandstone beds alternate with (Hook et al., 2012). This widespread interval of the Mancos: complete sections at laminated shale and siltstone (Fig. 7E–F). middle Cenomanian bentonite bed was Flying Eagle Canyon (Figs. 5A, A3.1) and At Flying Eagle Canyon, the lower originally 40Ar/39Ar dated at 94.93 ± 0.53 Mescal Canyon (Figs. 5C–D, 7, A3.3), and interval of the Mancos is ~113 m thick Ma (Obradovich, 1993). This date has an incomplete section at Reynolds Canyon and is mostly dark gray to black shale been recalculated to 95.53 ± 0.09 Ma, (Fig. A3.2). intercalated with thin (0.1–0.3 m thick) and a 206Pb/238U date of 95.87 ± 0.1 Ma Melvin (1963) reported a lower beds of ripple-laminated or bioturbated has been reported recently (Barker et al., Mancos Formation thickness of 90 m but sandstone as well as some equally thin 2011; Schmitz, 2012). In northwestern estimated it to be as much as 137 m thick beds of sandy limestone and calcarenite New Mexico, the “x” bentonite is just southwest of Durham Ranch in the north- (Figs. A3.1). Shale is black, except in the above the Paguate Member of the Dakota ern Caballo Mountains. Our measured lowermost 2 m, where the color is greenish Formation (e. g., Owen et al., 2005) (Fig. stratigraphic sections indicate that the gray. The black shale contains a few lime- 6). If identification of the “x” bentonite lower interval of the Mancos Formation stone concretions (in units 64 and 68) and in Mescal Canyon by Hook et al. (2012) is 113–156 m thick in Sierra County, but septarian concretions (units 69–73) in the is correct, then the Graneros interval at geometric considerations suggest thickness upper part. About 18 m above the base is Mescal Canyon is equivalent at least in could be as great as 210 m in the southern an ~5 m thick interval of limestone beds part to the Whitewater Arroyo Member of Fra Cristobals. Oil-test drilling records (0.1 and 0.3 m thick) containing bivalves, the Mancos Formation in northern New suggest a thickness range from 85 to 132 intercalated with shale containing thin Mexico (Fig. 6). This identification also m in central Sierra County (Table A2.2). lenses of limestone, that we identify as the supports correlation of the underlying In our measured stratigraphic sections, the Greenhorn Member. The shale interval sandstone interval at the top of the Dakota lower Mancos Formation is divisible into a below the Greenhorn Member is relatively Formation to the Paguate rather than lower, Graneros Member (12–18 m thick), poorly exposed at Flying Eagle Canyon the Cubero Tongue. A similar bentonite a medial, Greenhorn Member (5–13 m but does not appear to differ signifi- in a similar stratigraphic position in our thick) and an upper, Carlile Member cantly in lithology from shale above the Reynolds Canyon section (Fig. A3.2) may (90–136 m thick) (Figs. A3.1–A3.3). The Greenhorn Member. also be the “x” bentonite, though actual lower, Graneros Member is characterized At Reynolds Canyon (Fig. A3.2), dating or geochemical fingerprinting of by gray, sandy and silty shale and interbed- only about 18 m of the lower interval of these Sierra County bentonites is needed to ded sandstone (Fig. 7A), the Greenhorn the Mancos Formation is exposed below confirm identification of the “x” bentonite. by thin limestone beds intercalated with a fault. As at Flying Eagle Canyon, lime- shale (Fig. 7B–C), and the Carlile by black stone beds intercalated with shale about Paleontology and age shale with some thin, intercalated sand- 17 m above the Mancos base are assigned stone beds, especially in the upper part to the Greenhorn Member. Mancos strata Brief early mentions of fossils of “Benton (Figs. 5D, 7D–F). below the Greenhorn are gray shale with age” (equivalent to Cenomanian–Turo- Overall, the lower Mancos is a many thin sandstone interbeds and several nian: Cobban and Reeside, 1952) from succession of shale and siltstone with some thin bentonite layers. Sierra County noted by Darton (1928) are thin, intercalated limestone beds. The basal At Mescal Canyon (Fig. A3.3), the likely of invertebrate fossils from the lower 10 to 20 m (Graneros) are dark gray, lower interval of the Mancos Formation Mancos Formation. Fossils from the lower weathering greenish-gray or olive-gray, silt- is ~156 m thick. The Greenhorn interval Mancos Formation in Sierra County are free to slightly silty, and calcareous. Several is about 12 m above the base of the lower primarily of marine bivalves and ammo- beds of orange-weathering bentonite less Mancos in our stratigraphic section, nites. Hook et al. (2012) listed numerous than 3 cm thick are present (Fig. 5C). The though Hook et al. (2012, fig. 4) showed stratigraphic levels with index fossils of Greenhorn Member consists of shale like it as 59 m above the base. The Greenhorn middle Cenomanian, late Cenomanian

Spring 2019, Volume 41, Number 1 12 New Mexico Geology and early Turonian age in the lower Man- Depositional environments lime mudstone at Mescal Canyon, indi- cos Formation at Mescal Canyon. Our cating deposition from suspension. The collections from Flying Eagle and Reyn- The lower interval of the Mancos thin, partly marly, limestone beds of the olds canyons are less extensive but doc- Formation represents the upper part of the Greenhorn interval are autochthonous ument Cenomanian ages in the Graneros T1 transgression and the onset of the R1 deposits formed from suspension during and Greenhorn members of the Mancos regression of the Western Interior Seaway periods of little siliciclastic influx. At Formation (Fig. A6.1). (Molenaar, 1983). The turnaround point Flying Eagle Canyon some limestone beds According to the data of Hook et al. is in the Greenhorn Member, which rep- contain abundant shell fragments and are (2012), the Cenomanian–Turonian bound- resents highstand of the Western Interior partly echinoderm packstone to rudstone ary is in the Greenhorn Member in Mescal Seaway and possibly the highest sea level containing bivalve shells, bone fragments Canyon. Their data indicate that the of the Cretaceous (e. g., Kauffman and and teeth; we interpret these beds as storm Cenomanian Euomphaloceras septem- Caldwell, 1993). Thus, the lower interval layers. Subordinately, thin beds of lime seriatum zone is directly overlain by the of the Mancos Formation represents a mudstone are also present. Deposition Turonian Mammites nodosoides zone, marine depositional system that is divided of the Greenhorn Member occurred in so six ammonite zones are missing, a into: (1) offshore depositional settings that an offshore environment near the storm substantial hiatus or unconformity within accumulated shale with intercalated beds wave base. the Greenhorn interval (Mack et al., of siltstone and fine-grained sandstone 2016). However, we observed no physical (storm layers); and (2) offshore deposits Tres Hermanos Formation evidence of an unconformity at this strati- lacking storm layers, deposited below the graphic level. storm wave base (Mack et al., 2016). Lithostratigraphy At Mescal Canyon, the gray and Sedimentary petrography black, fissile, fossiliferous shales are marine Herrick (1900) gave the name “Tres deposits derived from suspended sediment Hermanos sandstone” to massive yellow Thin sandstone beds intercalated in the in an offshore environment below nor- sandstone about 23 m thick and lying 45 lower part of the Mancos Formation are mal wave base. Intercalated fine-grained to 75 m above the Dakota Formation in fine grained, well-sorted and composed sandstone beds displaying horizontal western Socorro and Valencia counties, of subangular to subrounded grains. lamination, ripple lamination, and rare New Mexico. He did not mention the The sandstone contains abundant hummocky cross-bedding are storm layers origin of the name, but it probably refers monocrystalline quartz, and subordinately (Seager and Mack, 2003). Thin limestone to Tres Hermanos Peaks, in sec. 26, T3N, polycrystalline quartz, chert grains, and beds represent intervals of little clastic R7W, northwestern Socorro County (Dane many detrital feldspar grains, including sediment input. et al., 1971). Various authors modified the plagioclase and untwinned potassium The facies of the lower interval of definition of the unit; Hook et al. (1983) feldspars (orthoclase). Most of the detrital the Mancos Formation at Flying Eagle established current usage. Wallin (1983) feldspars are slightly altered; some feldspar Canyon differs somewhat from that at was the first author to identify the Tres grains are partly replaced by calcite. The Mescal Canyon (Figs. A3.1, A3.3). At Hermanos in Sierra County (Fig. 3). sandstone contains brownish grains that Flying Eagle Canyon, the lower interval The Tres Hermanos Formation crops represent altered detrital grains, probably of the Mancos is composed of shale with out in Sierra County at Flying Eagle intermediate to basaltic volcanic rock abundant thin limestone beds and thin Canyon (Figs. 5A, A3.4, A3.1) and at the fragments. Rarely, volcanic rock fragments sandstone beds intercalated. Sandstone head of Reynolds Canyon (Figs. 8A, A3.4) containing plagioclase laths are present, beds are partly bioturbated, commonly in the Fra Cristobal Mountains, and at which are derived from intermediate to massive and more abundant in the upper Mescal Canyon in the northern Caballo basaltic volcanic rocks. Other rare grain part. The thick shale succession with many Mountains (Figs. 5D, 7F, 8B–C, A3.3). In types are fine-grained metamorphic (phyl- thin limestone and sandstone beds belongs these areas, the Tres Hermanos forms a litic) rock fragments and micas (biotite and to the lower offshore facies of Mack et al. small hogback, bench, or cuesta between muscovite). The sandstone is cemented by (2016). Interpretation of the sandstone valleys underlain by older and younger coarse blocky calcite. The sandstones ana- beds is difficult as the primary sedimentary shales. We measured the Tres Hermanos lyzed plot into the field of subarkose (cf. structures in many beds were destroyed to be 42 m and 43 m thick at Flying Eagle McBride, 1963; Pettijohn et al., 1987); the by bioturbation. The sandstone beds may and Reynolds canyons, which are closely average composition is Q70F17L13 (also see represent storm layers. At Mescal Canyon, adjacent, and 75 m thick at Mescal Can- the later section on petrofacies). in the lower interval of the Mancos, inter- yon, about 18 km to the south. Logs of 15 Based on field inspection, most calated sandstone beds, which probably oil-test holes near the Fra Cristobal Range limestone in the lower Mancos is lime represent storm layers, are more abun- show a thickness range of 60 to 90 m. mudstone. However, one limestone bed of dant, and limestone beds are rare except Hence, the formation appears to thicken the Greenhorn Member (Fig. A3.1, unit 53) in the Greenhorn Member. At both Mescal toward the southeast in Sierra County. is composed of packstone to rudstone con- Canyon and Reynolds Canyon, abundant To the north, in Socorro County, taining abundant echinoderm fragments, sandstone beds are intercalated in the the Tres Hermanos Formation is subordinately some bivalve shell fragments, Graneros interval of the Mancos below divided into three formal members: a many phosphatic fossil fragments (teeth, the Greenhorn Member, and these are basal sandstone interval, the Atarque bones) and a few detrital quartz grains interpreted to represent storm beds. Member, a medial coal-bearing interval, (Fig. A5.1C–D). The sediment is cemented The Greenhorn Member is composed the Carthage Member, and an upper sand- by calcite. of thin limestone beds alternating with stone interval, the Fite Ranch Member shale. Limestone beds are dominantly (Hook et al., 1983). The same basic strati-

Spring 2019, Volume 41, Number 1 13 New Mexico Geology graphic architecture is evident in the Tres The Atarque Member is ~8 m thick that observation or interpretation. Hermanos Formation in Sierra County, so at the head of Reynolds Canyon (Fig. Instead, the upper 25 m of the Campana the member names used in Socorro County A3.4), where it is composed of sandstone Member in our Mescal Canyon A section have also been applied in Sierra County, lithofacies similar to those at Flying (Fig. A3.3) is shale intercalated with beginning with Wallin (1983) (Fig. 3). Eagle Canyon. At Mescal Canyon (Fig. bioturbated sandstone. There are some However, it is worth noting that the strata A3.3), the Atarque is essentially the same limestone concretions in the upper part in Sierra County corresponding to the thickness and lithology as at Flying Eagle of this interval, and the bioturbation Carthage Member contain very little coal. Canyon. Some sandstone beds of the indicates some marine influence on Thus, Seager and Mack (2003, fig. 43) Atarque Member at Mescal Canyon are sedimentation. But, if the Fite Ranch depicted a single coal bed in the Carthage very calcareous and weather to large, Member is the transgressive shoreline of Member at Mescal Canyon, but this bed rounded, concretionary forms, often with the offshore marine D-Cross Member of is of very local extent. We observed thin coquinoid lenses of bivalve shells. the Mancos Formation (see below), it is layers of carbonaceous mudstone, but no The overlying Campana Member difficult to conceive how it would also be coal in these strata in Sierra County. is about 28–36 m thick at Flying Eagle underlain by offshore marine deposits of An important point is that the name Canyon, 28 m thick at the head of Reyn- the Campana Member. Carthage Member is a preoccupied name olds Canyon and 50 m thick at Mescal Capping the Tres Hermanos succes- and should not have been used for the Canyon. It is a slope-forming unit, com- sion is the Fite Ranch Member, which is 7 name of a formal lithostratigraphic unit prised mainly of non-fissile mudstone and to 10 m thick and composed of light-col- in New Mexico (use of duplicate names siltstone that is green, olive, or brownish ored, cross-bedded to massive sandstone runs contrary to the North American with a few lenticular bodies of sandstone having a few shale interbeds. At Flying Code of Stratigraphic Nomenclature). (0.3–2.7 m thick) that are either crossbed- Eagle Canyon (Fig. A3.1), the Fite Ranch Thus, the first use of the place name ded, laminar bedded, or very calcareous, Member is 2–7 m thick and consists of Carthage for a lithostratigraphic unit in and weather to a nodular texture. Some sandstone that is cross-bedded, laminar, the United States was by Owen (1856), mudstone layers are carbonaceous, but no or massive with some intercalated shale. who used the name “Carthage lime- coal layers were observed. At the ghost At Mescal Canyon (Fig. A3.3), the Fite stone” for a Pennsylvanian-age unit in town of Carthage in Socorro County Ranch Member is a thin sandstone unit Kentucky. That name continues to be about 80 km to the north, coal beds in the of dominantly trough cross-bedded sand- used in Kentucky, Illinois and Indiana Campana Member are also less than 1 m stone and subordinate massive sandstone, (throughout the Illinois basin) as a formal, thick (Osburn, 1983). and an intercalated thin mudstone bed. At member-rank unit (e.g., Jacobson et al., The Campana Member at Flying the head of Reynolds Canyon (Fig. A3.4), 1985; Shaver et al., 1986). Therefore, Eagle Canyon begins with a 9.5 m thick the Fite Ranch Member consists mostly the name Carthage Member of Hook interval (Fig. A3.1, units 99–107) that is of horizontally laminated or massive et al. (1983) should be abandoned and composed of brown shale with two thin sandstone beds, and its base is a trough replaced. Here, we replace it with the intercalations of massive sandstone (0.3 cross-bedded sandstone overlain by a thin, name Campana Member, named for and 0.4 m thick) in the lower part and two ripple-laminated sandstone. the Cerro de la Campana—a set of hills intercalated beds of horizontally laminated near the abandoned coal-mining com- sandstone (0.3 m thick) in the upper part. Paleontology and age munity of Carthage in Socorro County, The overlying interval is approximately where the type section of the Carthage 12 m thick (units 108–117) and sand- Fossils in the Tres Hermanos Forma- Member is located. stone-dominated with intercalated shale. tion are most abundant in the Atarque At Flying Eagle Canyon, we measured Sandstone includes horizontally laminated Member and are marine bivalves and rare two stratigraphic sections of the Tres sandstone (0.4 and 1.8 m thick) and mas- gastropods. There are also some fossil Hermanos Formation, one is less detailed sive sandstone (0.6 and 1.5 m thick). The oysters in coquinoid lenses in the Atarque (Fig. A3.1) and the other more detailed intercalated shale is brown, and the shale and the Fite Ranch members (Fig. 8C). At (Fig. A3.4). At the less detailed section (Fig. intervals are 1.5–3 m thick. Mescal Canyon, Hook et al. (2012) A3.1), the Atarque Member is 13.5 m thick At the head of Reynolds Canyon (Fig. identified Mytiloides mytiloides in the (Fig. A3.1, units 82–98) and composed of A3.4), the Campana Member is mostly Atarque Member and used that as the basis trough cross-bedded sandstone (individ- mudrock with a few thin, intercalated for an early Turonian age assignment. The ual beds 0.3–0.5 m thick), horizontally beds of cross-bedded sandstone and more overlying D-Cross Member of the Mancos laminated sandstone (0.9–2.6 m), massive numerous, thin beds of massive sand- Formation yields middle Turonian inverte- sandstone (0.5–0.7 m), shale (1.1 m), and stone. At Mescal Canyon (Fig. A3.3), the brate fossils (see below) that provide a mini- a few covered (shale) intervals (0.5–1.5 m Campana Member is dominantly shale mum age for the Tres Hermanos Formation. thick). The top of the Atarque Member is with thin limestone beds (<0.2 m) in the formed by a limy sandstone bed (0.6 m) lower part, and sandstone beds (mostly Sedimentary petrography that contains abundant bivalves (bivalve trough cross-bedded sandstone, also pla- coquina). At the more detailed section nar cross-bedded, ripple-laminated and Sandstone of the Atarque Member (Figs. (Fig. A3.4), the Atarque Member is 19 m massive sandstone) in the upper part. Sand- A5.1E–H) commonly is fine to medium thick and is also mostly trough cross-bed- stone intervals are up to 2.7 m thick. Seager grained, well-sorted and consists of ded sandstone and laminar sandstone with and Mack (2003, fig. 43) showed the upper subangular to subrounded grains. The shale interbeds, and its topmost bed is also 25 m of the Campana Member at Mescal most abundant grain type is monocrys- a bivalve coquina. Canyon as “offshore marine” shale talline quartz (including rare porphyry with ammonites, but we cannot verify quartz). Subordinate polycrystalline

Spring 2019, Volume 41, Number 1 14 New Mexico Geology quartz is present. Chert grains are a According to these authors, the Atarque of the Mancos Formation (Seager and common constituent. Detrital feldspar Member at Mescal Canyon represents a Mack, 2003). Wallin (1983, fig. 18) grains are present in moderate amounts vertical stacking of lower shoreface depos- considered the Fite Ranch Member to be and consist of untwinned potassium its (bioturbated sandstone with wave transgressive coastal barrier deposits, a feldspars, plagioclase, rare microcline oscillation ripples) to upper shoreface reasonable interpretation. and microperthite. Many detrital feldspars (cross-bedded sandstone with shell hash are slightly altered. The sandstone also and vertical burrows) to foreshore depos- contains fine-grained, brownish grains that its represented by horizontally laminated Mancos Formation–D-Cross represent altered detrital grains, probably sandstone with vertical burrows. Member volcanic rock fragments. Rare grain types However, our section of the Atarque are volcanic rock fragments, fine-grained Member at Mescal Canyon (Fig. A3.3) Lithostratigraphy metamorphic rock fragments, rock frag- and that of Wallin (1983, fig. 7) show a ments composed of quartz and feldspar, different succession of lithofacies than Dane et al. (1957) gave the name “D-Cross micas (muscovite and biotite) and opaque does the section of Seager and Mack Tongue of Mancos Shale” to a shale-dom- grains. Broken fragments (xenomorphs) of (2003). Our Mescal Canyon section of inated unit overlying the Tres Hermanos zircon grains are common accessory min- the Atarque Member shows a lower part Formation in the vicinity of D-Cross erals; less common are grains of greenish with finer-grained, planar and ripple lami- Mountain in northwestern Socorro County. tourmaline. One thin section of sandstone nated sandstone overlain by an upper part Wallin (1983) extended recognition of the from the Fite Ranch Member (Fig. A5.2A) composed of coarser-grained sandstone D-Cross into Sierra County. shows that it is similar to the Atarque with trough cross-bedding, wave ripples Thus, the upper part of the Mancos Member sandstone petrographically. and bioturbation. Coquina beds are Formation in Sierra County is the D-Cross In some of the sandstone beds, intercalated in the lower and upper parts. Member, a 95–146 m thick interval of authigenic quartz overgrowths on detrital Wallin (1983) interpreted the succession as mostly gray and greenish-gray shale inter- quartz grains are a common cement type. a distributary-mouth bar of the Atarque calated with some prominent sandstone Other sandstones contain coarse poikilo- Member above prodelta sandstone interca- beds, especially in its upper half. In Mescal topic calcite cement that partly replaces lated with shale of the upper part of the Canyon, Hook et al. (2012) assigned these detrital feldspar grains. Sandstone Carlile Member. At Flying Eagle Canyon sandstone beds to the Gallup Formation. containing a few quartz overgrowths and at the head of Reynolds Canyon, However, from the point of view of map- and small amounts of matrix are also a coarsening-upward trend within the pable lithostratigraphy, these sandstones present. All sandstone samples of the Tres Atarque Member is not visible. The Atarque are in a shale-dominated interval better Hermanos Formation are classified as Member is composed of trough cross-bed- assigned to the D-Cross Member (also see subarkose (cf. Pettijohn et al., 1987). ded, horizontally laminated, and massive Molenaar (1983) and Seager and Mack Following the classification of McBride sandstone, alternating with covered (shale?) (2003), who assigned these sandstones to (1963), most samples plot into the field intervals. Sandstone at the top contains the D-Cross.) of subarkose, and a few samples into abundant bivalve shells. We interpret The D-Cross is an upward-coarsening the field of lithic subarkose. The average the succession as deposits of an upper succession of shale and siltstone, with composition is Q79F15L6 (see discussion of shoreface to foreshore environment, in much sandstone in the upper part. petrofacies below). agreement with Seager and Mack (2003). The shale is dark gray, weathering Seager and Mack (2003) interpreted olive-gray, and changes from soft and flaky, Depositional environments the strongly bioturbated shale of the basal calcareous clay-shale in the lower part to Campana Member above the Atarque weakly laminated, silty shale in the upper Regionally, the Tres Hermanos Formation Member as lagoonal deposits, the over- part. Laminae and thin interbeds of silt- represents the upper part of the R1 lying sandstone with root structures and stone and very fine sandstone increase in regression and the lower part of the T2 coal as coastal swamp deposits, the over- abundance upward. The most distinctive transgression of the Western Interior Sea- lying thick sandstone as fluvial channels, feature of the D-Cross is large septarian way (Molenaar, 1983). Thus, the Atarque and the mudstone with thin intercalated concretions that range up to a meter across Member represents the regressive shoreline sandstone beds above as overbank and and are composed of dark gray, dolomi- facies at the end of R1, and the Fite Ranch crevasse-splay deposits. Wallin (1983, critic limestone that weathers rusty orange. Member represents the transgressive shore- fig. 16) interpreted the lower 6 m of the Ammonites and other marine fossils are line at the beginning of T2. The Campana Campana Member as interdistributary bay present in some of these concretions. Member represents fluvio-deltaic deposi- and lacustrine deposits, overlain by fluvial In our two complete measured section landward of these shorelines, and the channel, crevasse-splay and overbank tions, the D-Cross is 95 m thick at Flying “turnaround point” between R1 and T2 is floodplain deposits, and we concur with Eagle Canyon (Fig. A3.1) and 146 m within the Campana Member. his interpretation. thick at Mescal Canyon (Fig. A3.3), about According to Seager and Mack Sandstones of the Fite Ranch Member 18 km to the south. Logs of eight oil-test (2003), at Mescal Canyon, sandstone of were interpreted as lower shoreface holes suggest a thickness range from 62 to the Atarque Member coarsens upward and deposits by Seager and Mack (2003). The 165 m. grades from sandstone with symmetrical uppermost sandstone of the Fite Ranch We measured three stratigraphic sec- ripples to trough cross-bedded sandstone Member was posited to be a transgressive tions of the D-Cross Member: a complete and sandstone with horizontal lamination. lag, which defines the flooding surface that section at Flying Eagle Canyon (Fig. A3.1) The degree of bioturbation decreases separates the Tres Hermanos Formation and another at Mescal Canyon (Fig. A3.3), up section (Seager and Mack, 2003). from the overlying D-Cross Member and an incomplete section at the head of

Spring 2019, Volume 41, Number 1 15 New Mexico Geology Reynolds Canyon (Fig. A3.4). At Flying published provenance of this fossil was al. (2012) listed ammonites of the Priono- Eagle Canyon (Fig. A3.1), the lower part incorrect; it actually came from the Niobr- cyclus novimexicanus and P. germari zones of the D-Cross Member (units 124–134) ara Formation of Kansas. of Turonian age. is 34.5 m thick and consists of shale with Kennedy et al. (2001, fig. 118) We collected bivalves and ammonites intercalations of trough cross-bedded illustrated a specimen of the ammonite from the D-Cross Member at both Flying sandstones that are lenticular, with a maxi- Prionocyclus germari collected from the Eagle and Reynolds canyons (Figs. A6.2, mum bed thickness of 0.6 m; two thin beds D-Cross Member in Mescal Canyon. Also, A6.3) that are of Turonian age. These will (each 0.1 m thick) of massive sandstone; at Mescal Canyon, Hook et al. (2012) listed be published more extensively elsewhere. thin sandstone lenses intercalated in shale an ammonite assemblage stratigraphically The lower D-Cross includes the bivalves (unit 130); shale containing large sandy low in the D-Cross Member with Coilo- Cameleolopha bellaplicata (Shumard) limestone concretions with oyster shells poceras inflatum, Hourcquia mirabilis and and Inoceramus dimidius (White), and (0.4 and 1.5 m thick); and greenish-gray Prionocyclus macombi. This is a “Juana the ammonites Coilopoceras inflatum and shale intervals (1.5–11 m thick). The upper Lopez age” assemblage of middle Turonian Prionocyclus macombi (Meek), whereas part of the D-Cross Member is 60.5 m age. In strata they assigned to the lower the upper D-Cross contains the ammonite thick and composed of shale (individual part of the Gallup Formation, but that we Prionocyclus germari, confirming the shale intervals are up to 20 m thick), include in the D-Cross Member, Hook et records reported by Hook et al. (2012). and intercalated sandstone units that are thicker than sandstone beds in the underlying, lower part of the D-Cross Member. Campana The following sandstone lithotypes are Member present: trough cross-bedded sandstone; horizontally laminated sandstone; massive sandstone; rare, ripple-laminated sand- Atarque stone; two oyster beds (coquina) in the Member upper part; and shale intervals (up to 20 m thick). The shale of unit 137 contains large limestone concretions. At the head of Reynolds Canyon (Fig. A3.4), an incomplete section of the D-Cross Member is about 57 m thick. Here, the A B lower D-Cross is almost entirely greenish-gray shale with scattered limestone concretions, except for three thin (0.3–0.7 m thick), persistent beds of concretions, one with ammonites (unit 40). At Mescal Canyon (Fig. A3.3), the lower 30 m of the D-Cross Member is mostly shale, whereas the upper 60 m include sandstone units (up to 8.1 m thick) alternating with shale and siltstone. The dominant sandstone lithofacies is trough cross-bedded sandstone (Fig. 8E), and, subordinately, horizontally laminated, pla- C D nar cross-bedded, and massive sandstone. Several horizons are intercalated that contain large sandy limestone concretions (0.2–1.2 m in diameter). Some siltstone (units 76 and 78) and shale (units 88 and ammonite 94) intervals also contain concretions. Stratigraphically high in the member, an oyster coquina (0.3 m) is intercalated in shale (unit 93).

Paleontology and age E F Cope (1871) named a mosasaur, Liodon dyspelor, based on bones supposedly FIGURE 8. Photographs of selected outcrops of the Tres Hermanos Formation and D-Cross Member of the Mancos Formation in Sierra County. A, Lower part of Atarque Member at section at head collected “from the yellow beds of the of Reynolds Canyon. B, Atarque Member and lower part of overlying Campana Member at Mescal Niobrara epoch of the Jornada del Muerto, Canyon. C, Fossil oysters in Atarque Member at Mescal Canyon. D, Well exposed, cyclically bedded near Fort McRae, New Mexico” (also see shale of D-Cross Member of Mancos Formation at Flying Eagle Canyon section. E, Sandstone bed Cope, 1875; Russell, 1967). However, stratigraphically high in D-Cross Member at Mescal Canyon. F, Ammonite fossil (Coilopoceras as Parris et al. (1997) demonstrated, the inflatum) in D-Cross Member at Flying Eagle Canyon. Rock hammer is 28 cm long.

Spring 2019, Volume 41, Number 1 16 New Mexico Geology We infer that D-Cross shale beds without sandstone intercalations are offshore marine muds depos- Flying Eagle ited below wave base. Dark gray, Canyon Formation fissile shales that locally contain Gallup Formation concretions and intercalated fine-grained sandstone beds with horizontal burrows and scattered bivalve shell fragments of the upper part of the D-Cross Member at Mescal Canyon are interpreted here as lower shoreface deposits. Thicker sandstone units displaying trough cross-bedding may represent upper shoreface deposits.

Gallup Formation

A Lithostratigraphy

Sears (1925) named the “Gallup sandstone member of the Mesav- erde formation” for the town of Gallup in northwestern New Mexico. Wallin (1983) was the first to assign strata to this unit in Sierra County. Because lithology and stratigraphic relationships here are a good match for those in the Gallup area, we accept and continue this usage, as have others (e.g., Seager and Mack, 2003; Hook et al., 2012; Mack et al., 2016). In central Sierra County, the Gallup Formation is well exposed at Flying Eagle Canyon (Fig. A3.1) and at Mescal Canyon (Fig. A3.3). At both locations it is a B prominent, light-colored interval of tabular bedded, bioturbated FIGURE 9. Photographs of selected outcrops of the Gallup Formation at Mescal Canyon (A) and Flying Eagle Canyon (B). and cross-bedded sandstone with minor shale intercalations (Fig. 9). Sedimentary petrography (cf. Pettijohn et al., 1987) or subarkose to Unweathered colors are white and lithic subarkose (cf. McBride, 1963). The very pale orange, and weathered colors

In the D-Cross Member of the Mancos average composition is Q72F16L12. are moderate brown and light brown. Formation, fine-grained sandstone is The section of the Gallup Formation at well-sorted and has a composition similar Depositional environments Mescal Canyon we measured is ~32 m to the thin sandstone beds intercalated thick. At Flying Eagle Canyon the Gallup in the lower Mancos Formation and in Regionally, the D-Cross Member represents Formation is 19 m thick. These values the Tres Hermanos Formation: abundant the upper part of the T2 transgression and compare to a range of 6 to 30 m in five monocrystalline quartz, subordinately the lower part of the R2 regression of the oil-test holes. polycrystalline quartz, chert grains, many Western Interior Seaway (Molenaar, 1983). At Flying Eagle Canyon (Fig. A3.1), detrital feldspar grains, altered brownish Seager and Mack (2003) suggested that the Gallup Formation is mostly sandstone. grains, and rare volcanic and metamorphic maximum water depth (the “turnaround In the lower part, trough cross-bedded (phyllitic) rock fragments (Fig. A5.2B). point”) is near the middle of the D-Cross, and horizontally laminated sandstone The detrital grains are cemented by coarse just below where thick sandstone beds are are present; the upper part is composed blocky calcite; rarely, quartz grains dis- present (this would be unit 139 or 142 of finer-grained, horizontally laminated play authigenic overgrowths of quartz. in our Flying Eagle Canyon section: Fig. and massive sandstone. One coquina Sandstone samples from the D-Cross A3.1; and unit 78 in our Mescal Canyon bed is intercalated in the middle of the Member plot into the field of subarkose section: Fig. A3.3). formation. Shale is rare and intercalated

Spring 2019, Volume 41, Number 1 17 New Mexico Geology in the lower and middle parts of the The average composition is Q78F11L11 (also group,” and Collier (1919) named them Gallup Formation. see the section below on petrofacies). the (ascending): Point Lookout Sandstone, At Mescal Canyon (Fig. A3.3), the Menefee Formation, and Cliff House Gallup Formation is mostly composed Depositional environments Sandstone. These are strata of early-mid- of sandstone and minor shale and three dle Campanian age, between the Monte- coquina beds (each 0.3–0.6 m thick). The Gallup Formation represents the shore- zuma Valley Member of the Mancos For- Sandstone lithofacies are horizontally line of the R2 regression of the Western mation below and the Lewis Formation laminated, trough cross-bedded, ripple Interior Seaway (Molenaar, 1983). Accord- above (e.g., Leckie et al., 1997). Thus, a laminated, bioturbated, or massive. Trough ing to Molenaar (1973, 1974), in northern strict application of the name Mesaverde cross-bedded sandstone contains abundant New Mexico the Gallup Formation is a should be as a group-rank unit to encom- bivalve shells and shell fragments. succession of coastal barrier, strand plain or pass these strata and their homotaxial delta-front sandstones that grade seaward (essentially correlative) strata to the south Paleontology and age into offshore marine mudstone of the (e. g., Reeside, 1924). Mancos Formation and landward into non- In early, mostly reconnaissance-level At Mescal Canyon, Hook et al. (2012) marine or brackish coastal-plain deposits work, Mesaverde Formation (or Group) listed the bivalves “Lopha” sannionis of the coal-bearing Dilco Member of the was a useful lithostratigraphic term to (White), Crassostrea glabbra (Meek and Crevasse Canyon Formation. apply to a substantial portion of the Hayden), Inoceramus cuvieri (Sowerby), At Mescal Canyon, Seager and Cretaceous section in Sierra County when and Mytiloides incertus (Jimbo) from Mack (2003) interpreted the upper part the architecture of that section was not the Gallup Formation. They assigned the of the D-Cross Member and lower to understood in detail and its correlation Gallup Formation to the Prionocyclus middle parts of the Gallup Formation remained imprecise. Now, we have pro- germari (Reuss) ammonite zone of late as prodelta, delta-front and distribu- gressed beyond such a general understand- Turonian age, largely because Mytiloides tary-mouth bar deposits, respectively. ing, so a broad term like Mesaverde is no incertus is not known from strata younger Coquina beds (oyster-bearing sand- longer needed for Cretaceous strata in than the P. germari zone (Hook et al., 2012). stones) above the distributary-mouth Sierra County. In Flying Eagle Canyon, we collected bar sandstones are interpreted by them Crevasse Canyon Formation has also “Lopha” sannionis from the lower part as deposits of brackish bays on the lower been applied to much of the Cretaceous of the Gallup Formation. Fragments of delta plain. The upper part of the Gallup section in Sierra County, as a virtual bivalves, fossil logs, and shark’s teeth are Formation is interpreted as delta-front synonym of earlier uses of Mesaverde also present locally. deposits, over- and underlain by channel (Fig. 3). However, the typical Crevasse sandstones that probably represent distrib- Canyon Formation strata of west-cen- Sedimentary petrography utary channels, tidal channels or estuaries tral New Mexico have a very different (Seager and Mack, 2003). Wallin (1983, stratigraphic architecture and lithologic Sandstone of the Gallup Formation (Fig. fig. 21) interpreted Gallup deposition as a content than do the strata termed A5.2 C–F) is mostly fine to medium progression upward from lower shoreface Crevasse Canyon in Sierra County. Thus, grained, moderately to well-sorted, and to upper shoreface deposits, capped by the Crevasse Canyon in west-central New grains are dominantly subangular. The foreshore sandstones. Mexico has two substantial intervals mineralogical composition is similar to characterized by interbedded sandstone, sandstone of the Atarque Member of the Flying Eagle Canyon Formation siltstone, and mudstone containing thick, Tres Hermanos Formation and consists economically important coals: its basal mainly of monocrystalline quartz, sub- Lithostratigraphy Dilco Member and uppermost Gibson ordinately polycrystalline quartz, many Member. This is quite different from the chert grains, many detrital feldspar grains, In Sierra County, beginning with Harley strata termed Crevasse Canyon Formation small amounts of volcanic rock fragments (1934), much of the Cretaceous section in Sierra County, which lack the thick containing plagioclase laths, fine-grained above the lower Mancos or above the Tres coal zones, so use of the name Crevasse brownish altered grains, rare fine-grained Hermanos Formation has been assigned Canyon here is abandoned. The strati- metamorphic rock fragments, and rare to the Mesaverde Formation (or Group) graphic architecture observed in Sierra grains displaying spherulitic texture (Fig. 3). Seeking to introduce greater pre- County, a lower mudstone-dominated (derived from acidic volcanic rocks). cision, Wallin (1983) introduced the term unit and an upper sandstone-dominated Other rare grains include micas (muscovite Crevasse Canyon Formation for these unit with quartz and chert pebbles near and biotite), opaque grains, and zircon. strata, and most subsequent authors the top, is a poor fit for the type Sandstone is cemented by coarse, blocky, followed suit. However, we find both Crevasse Canyon. partly poikilotopic calcite cement. Locally, Mesaverde and Crevasse Canyon to be An excellent, locally derived name, authigenic quartz overgrowths on detrital inappropriate names for these strata in Ash Canyon, already is available for the quartz grains and small amounts of matrix Sierra County, and propose to substitute upper part of the “Crevasse Canyon” suc- are present. locally derived names. cession in Sierra County. For the lower part, Sandstone samples of the Gallup Mesaverde Formation (or Group) only informal terms such as “coal-bearing Formation are subarkose to sublitharenite was originally the “Mesa Verde group” member” and “barren member” have according to the classification of Pettijohn et of Holmes (1877), named after the well- been applied previously. For the purpose al. (1987) and subarkose, lithic subarkose and known mesa east of Cortez in southwest- of recent geologic mapping in the area, sublitharenite according to McBride (1963) ern Colorado. Holmes (1877) recognized Cikoski et al. (2017) used the term “unit of three informal units in his “Mesa Verde Flying Eagle Canyon” for the lower unit.

Spring 2019, Volume 41, Number 1 18 New Mexico Geology We thus propose the term Fly- at the type section and 480 m at Mescal The Flying Eagle Canyon and Tres ing Eagle Canyon Formation to refer Canyon. The relatively thin type section of Hermanos formations contain a similar to strata previously included in the lower the Flying Eagle Canyon Formation could suite of lithologies and can be difficult part of the Mesaverde Formation (Group) in reflect depositional thinning, an uncon- to distinguish when encountered in fault Sierra County (Fig. 3). The name is in refer- formable contact with the overlying Ash blocks. The most diagnostic features of the ence to Flying Eagle Canyon in the southern Canyon Formation, or tectonic thinning Flying Eagle Canyon, lacking in the Tres Fra Cristobal Mountains, where the type of the section not obvious in the field, Hermanos, are giant (commonly 2 to 3 section of the formation was measured or a combination of two or more of meters across) sandstone concretions that (Fig. A3.1). those causes. weather dark brown. The Flying Eagle Recognition of (and in several cases, The Flying Eagle Canyon Formation is Canyon Formation might also be mistaken quadrangle-scale mapping of) the litho- mostly fine-grained strata with subordinate for the younger José Creek Formation, but stratigraphic units we term Flying Eagle fine- to medium-grained sandstone inter- on close inspection, most sandstone in the Canyon and Ash Canyon formations vals that are light gray, pale yellow, and latter unit contains a high proportion of (see below) can be found in earlier work light olive-gray. Fine-grained strata are volcanic rock fragments, and quartz is at on the Cretaceous of Sierra County (e.g., composed of olive-gray to light olive-gray most a minor constituent. Sandstone of the Melvin, 1953; Mack and Seager, 1993; mudrock (mudstone, siltstone and shale) Flying Eagle Canyon Formation contains Seager, 1995b, c) that recognized that the interbedded with very fine- to fine-grained abundant quartz and much pink feldspar, “Mesaverde” or “Crevasse Canyon” strata sandstone. Sparse, impure coal is present but lacks volcanic clasts. Some poorly can be divided into a lower, mudrock-dom- close to the base. Mudstone and siltstone preserved plant stems and roots and a inated unit, and an upper, sandstone/ is largely dark green to olive, but some few pieces of silicified wood are present conglomerate-dominated unit. Melvin layers are dark red, purplish gray, and in the Flying Eagle Canyon Formation, (1963) termed these the Cuesta Pelado and ochre yellow. Layering is absent to weakly but wood is far less common than in the Mescal Creek formations, but these names developed in fine strata, but relatively thin overlying Ash Canyon Formation. were never published. Seager (1995b, c) (<1 m thick) interbeds of very fine- to fine- At the type section (Fig. A3.1), the termed the lower unit the “main body” of grained sandstone are commonly present; Flying Eagle Canyon Formation is 151 m the Crevasse Canyon Formation and the these interbeds variably exhibit horizontal thick and can be divided into two inter- upper unit the Ash Canyon Member. The laminations, ripplemarks, root traces, vals: (1) sandy lower part, approximately simplest nomenclatural approach here is or burrows (Seager and Mack, 2003). 82 m thick (Fig. A3.1, units 169–212); to name the lower unit and, as did Seager Sandstone-dominated strata rarely exceed and (2) mudstone-dominated upper part, (1995b, c), expand the concept of the Ash 15 m in thickness and are channel-fill approximately 69 m thick (Fig. A3.1, Canyon Member of Bushnell (1955a) to complexes that are single- to multistorey units 213–230). In the lower part, sand- encompass the upper unit. (seldom more than two storeys), generally stone forms thin (0.1–0.3 m) beds and The Flying Eagle Canyon Formation less than 6 m in overall thickness. The lenses (Sh, Sm), and thicker sandstone is composed of non-fissile mudstone, silt- sandstone is in thin to very thick, tabu- units (up to 3.7 m thick) composed of stone, and lenticular to tabular bodies of lar to lenticular beds that are internally trough cross-bedded sandstone (St), weakly cemented sandstone. These strata cross-bedded (lithofacies St, Sp); medium horizontally laminated sandstone (Sh), erode to slopes and valleys, in contrast to to very thick beds commonly correspond ripple-laminated sandstone (Sr), and the light-colored Gallup Formation below to a single-storey channel-fill body, with shale intervals (Fm). The upper part is and the sandstone-dominated Ash Canyon tangential or planar foresets, and trough mostly shale (Fm) with a few intercalated Formation above. Thus, these formations cross-bedding is commonly observed. sandstone units that are 0.1–1.2 m thick: are readily differentiated on the ground and Some sandstones are horizontal-planar massive (Sm), horizontally laminated in aerial imagery. Under various names, the laminated (Sh), ripple laminated (Sr), or (Sh), and ripple-laminated sandstone (Sr), Flying Eagle Canyon Formation appears as massive (Sm). Paleoflow directions indi- and rare trough cross-bedded sandstone a mapping unit on several 1:24,000 scale cated on the Cikoski et al. (2017) map, (St). Shale units are 1 m to more than geologic maps (Lozinsky, 1985; Mack and based on trough orientations, are toward 25 m thick. Seager, 1993; Seager, 1995b, 2007; Seager the north and east, which agrees with the The Fossil Forest section (Figs. 11A, and Mack, 2005; Cikoski et al., 2017), findings of Wallin (1983). The sand is fine A3.6) encompasses about 85 m of the and we are using it thus in a forthcoming to medium grained, subangular (only a upper part of the Flying Eagle Canyon geologic map of the Fra Cristobal Range. few subrounded grains) and well-sorted Formation. The base of the formation is With fair certainty, the Flying Eagle (unit description modified from Cikoski et not exposed, but the overlying contact Canyon Formation can be identified on al., 2017). with the Ash Canyon Formation is well the logs of several oil-test holes drilled Impure coal is present at or within a exposed. The exposed Flying Eagle in northern Sierra County. However, few meters of the base of the Flying Eagle Canyon strata are mostly shale (54% of only two of these completely penetrated Canyon Formation (Fig. 10A–B). Carbo- the measured thickness) and somewhat the unit. Thus, the Flying Eagle Canyon naceous layers up to about 30 cm thick are less sandstone (46%). Most of the sand- Formation is about 120 m thick in the visible in the type section and also in the stone beds are trough cross-bedded, but Summit #A-1 Mims test, drilled about 8 south bank of Reynolds Canyon, southeast some are laminar, and a few are massive km north of Truth or Consequences, and of Bert Cook Well (Fig. A4.1). Coal is also or bioturbated. 221 m thick in the Beard Oil #1 Jornada present at about the same stratigraphic In the Mescal Canyon B section (Figs. del Muerto test hole, drilled about 10 km position in the Cutter sag, and formerly 10B, A3.5), the Flying Eagle Canyon suc- southeast of Engle (Table A2.2). These was mined on a small scale (Wallin, 1983). cession is composed of alternating shale thicknesses compare to 151 m measured and sandstone, and rare conglomerate

Spring 2019, Volume 41, Number 1 19 New Mexico Geology thin cross-bedded sets (<50 cm). Some of the trough cross-bedded sandstones contain intraformational (mostly mudstone) rip-up clasts near their bases. Bioturbation is rare. Sandstone of unit 118 displays synsedimentary deformation structures (dewatering structures). Sandstone of unit 13 contains sandstone concretions in its uppermost part; subordinately, massive sandstone (Sm), ripple-laminated sandstone (Sr), and minor sandstone with planar cross-bedding (Sp) are present. One thin conglomerate bed (0.5 m) containing intraformational clasts (mudstone pebbles) A and displaying trough cross-bedding (lithofacies Gt) is intercalated in the middle part of the formation at the base of a trough cross-bedded sandstone unit (Fig. A3.5, unit 82). The contact of the Flying Eagle Canyon Formation with the overlying Ash Canyon Formation is marked by a change to lighter-colored, more resistant, more thickly bedded sandstone and a decrease in the amount of mudstone and siltstone. The contact is B mapped at the base of the lowest thick, C light-colored, quartz-rich, resistant bed of sandstone. This contact is typically sharp and erosive, but probably represents only a minor disconformity. It is likely that the lowest sandstone included with the Ash Canyon is not the same age throughout the study area. Seager and Mack (2003) reported that large- scale intertonguing takes place between lower Crevasse Canyon (Flying Eagle D E Canyon) and Ash Canyon strata in the Caballo Mountains. FIGURE 10. Photographs of selected outcrops of the Flying Eagle Canyon Formation. A, Basal coaly beds overlain by channel sandstone, Flying Eagle Canyon. B, Basal coal bed at Mescal Canyon. C, Cross-bedded sandstone, Mescal Canyon. D, Calcareous sandstone, Mescal Canyon. E, Gray shale with ironstone beds, Mescal Canyon. Paleontology and age

Fossils of plants, marine bivalves, and a and coal beds. Two thin coal beds (units 3 Sandstone of the Flying Eagle turtle are known from the Flying Eagle and 5), each 0.3 m thick, are intercalated Canyon Formation at the Mescal Canyon Canyon Formation. Lozinsky (1985) listed in brown shale near the base of the Flying B section (Fig. A3.5) is present as different fossil plants from one locality near Mescal Eagle Canyon Formation. Another thin lithotypes: (1) thin sandstone beds and Canyon as “Sequoia montana” [sic], Ficus coal bed (unit 68, 0.3 m thick) is devel- lenses intercalated in shale are mostly planicostata Lesquereux, cf. Dryophyllum oped on top of a sandstone interval about massive (Sm), subordinately horizontally sp., cf. Laurophyllum wardiana (Knowl- 224 m above the base (Fig. A3.5). Shale laminated (Sh), rarely ripple laminated ton), cf. Dillenites cleburni (Lesquereux), is dominantly brown, but in the upper (Sr), and trough cross-bedded (St). Bed Cercidiphyllum sp., and cf. Quercus part (Fig. A3.5, units 102–134) it is gray, thickness varies from 0.1 to 0.8 m. The viburnifolia Lesquereux (identifications by olive gray and greenish gray. Brown shale calcareous sandstone of unit 97 contains Coleman Robinson). Most of these taxa, at of unit 60 contains large (0.5 m in diam- oyster shells; (2) thicker sandstone units least at the generic level, are known from eter) calcareous sandstone concretions. (1–13.2 m thick) are mostly trough the late Campanian Fruitland or Kirtland Silicified, fossil logs are present in the cross-bedded (lithofacies St). Two types of formations in the San Juan Basin of north- lower 1 m of brown shale of unit 81. Dark trough cross-bedded sandstone can be dis- western New Mexico (e.g., Tidwell et al., yellowish orange shale (Fig. A3.5, unit 95) tinguished: large-scale cross-bedding with 1981), but it is not clear that they are of contains ironstone beds and concretions thick cross-bedded sets (mostly 50–100 precise biostratigraphic significance. Fossil (Fig. 10E). cm), and small-scale cross-bedding with wood is also present but unstudied.

Spring 2019, Volume 41, Number 1 20 New Mexico Geology The bivalve fossils include fragmentary Coarse, blocky calcite cement is present in and Sm—forming the architectural ele- oysters and are present in a few beds (see some sections. ment channel (CH) in combination with above). Lichtig and Lucas (2016) described The average composition of sandstone sandy bedforms (SB), sensu Miall (1996, a new species of turtle, Neurankylus notos, of the Flying Eagle Canyon Formation is 2010). Mudstone units are assigned by us from the Flying Eagle Canyon Formation Q84F6L10 (sublitharenite). Most samples to the architectural element FF (overbank east of the Caballo Mountains (NMMNH plot into the field of sublitharenite, and fines). Thinner sandstone intercalations locality 9158). This is likely the oldest rarely into the fields ofquartz arenite and (<2m thick) within the mudstones, rep- record of Neurankylus, which is mostly a subarkose (classification after Pettijohn et resented by lithofacies St, Sh, Sr and Sm, Campanian–Paleocene genus elsewhere al., 1987). Following the classification of are interpreted by us as crevasse-channel (Lyson et al., 2016). Thus, the fossils currently McBride (1963), most samples plot into and crevasse-splay deposits (architectural known from the Flying Eagle Canyon do not the field of sublitharenite, and subordi- elements CR and CS). provide a precise age assignment, although nately into the fields of lithic subarkose, We thus interpret the Flying Eagle they are consistent with a possible minimum and, rarely, subarkose and quartz arenite. Canyon Formation as deposits of a sandy age of Campanian. meandering to anastomosing fluvial system However, the base of the Flying Depositional environments formed under semihumid to humid climatic Eagle Canyon Formation is no older conditions (indicated by gray colors of mud- than the underlying late Turonian Gallup To the north of Sierra County, the Crevasse stone, “wet” paleosols (cf. Seager and Mack, Formation, and the lower part of the unit Canyon Formation represents coastal 2003), and the presence of thin coal beds is homotaxial with the Dilco Coal Mem- deposits associated with the R2 regression, and fossil plant debris within the mudstone ber of the Crevasse Canyon Formation the overlying T3 transgression, and the R3 facies). Lateral variations in thickness and in west-central New Mexico. This means regression of the Western Interior Seaway, facies are present among the three measured the base and lowermost part of the Flying and was deposited primarily between the T3 sections illustrated here. At the type section, Eagle Canyon Formation are likely of and R3 paleoshorelines (Molenaar, 1983, the upper Flying Eagle Canyon Formation Turonian age, and the unit probably fig. 9) along a belt that extended northwest consists of a high proportion of mudstone. includes Coniacian-age strata, though its to southeast from Gallup through Socorro At the Fossil Forest section, the exposed upper age limit cannot be determined with to near Carrizozo. The R2 regression is upper portion of the Flying Eagle Canyon available data. recorded in Sierra County by the upper Formation is more sandy. Thickness also part of the D-Cross Member of the Man- varies considerably between sections of the Sedimentary petrography cos Formation, the Gallup Formation and Flying Eagle Canyon Formation. the lowermost strata of the Flying Eagle In the Flying Eagle Canyon Formation Canyon Formation, the latter being homo- “Engle coal field” (Figs. A5.2G–H, A5.3A–D), the grain size taxial with the Dilco Coal Member of the of sandstone is mostly very fine- to medi- Crevasse Canyon Formation to the north- Lee (1905) coined the term “Engle coal um-grained but may locally range to coarse- west. Thus, the rocks in Sierra County are field,” but there is very little coal in this to very coarse-grained; it is very seldom equivalent to the lower part of the Crevasse “field” and there has never been any pebbly. Sorting ranges from poorly sorted Canyon Formation and were deposited commercial production. As Lee (1905, p. in pebbly sandstone, but the more common about 100–120 km south (southwest) of the 240) well stated, “little development has fine- to medium-grained sands are mostly T3 transgression shoreline. A thin sandstone been accomplished in the Engle area and well-sorted. Detrital grains are subangular bed containing oyster shells is present at our its importance as a coal field is doubtful.” to subrounded. The most common grain Mescal Canyon B section approximately Mason (1976) estimated that only about types are monocrystalline quartz (including 339 m above the base of the Flying Eagle 0.2% of the Mesaverde strata in the north- porphyry quartz), polycrystalline quartz Canyon Formation, indicating some marine ern Caballo Mountains are coal, and our (including stretched metamorphic), and influence on sedimentation (Fig. A3.5, unit measured stratigraphic sections suggest abundant volcanic grains. Detrital feldspars 97). However, it is not certain that this is that may be a generous estimate. Thus, are sparse (average 6%) and include potas- a record of the T3 transgression in Sierra coal beds in our sections are almost entirely sium feldspars (untwinned, microcline, per- County (see later discussion). restricted to the basal Flying Eagle Canyon thite) and plagioclase. Detrital feldspars are Seager and Mack (2003) interpreted Formation and they are few in number partly altered to clay minerals, and partly the lower member of the Crevasse (one to three beds) and mostly less than replaced by calcite cement. The sandstone Canyon Formation (Flying Eagle Canyon one meter thick (Figs. A3.1, A3.5). Wal- also contains a few granitic rock fragments, Formation) as fluvial deposits. According lin’s (1983) use of the term “coal-bearing rare volcanic chert grains displaying a to Seager and Mack (2003), sandstone member” to refer to the lower part of the spherulitic texture, and rare granophyric beds of the Flying Eagle Canyon are mainly Mesaverde Formation thus is somewhat grains, metamorphic rock fragments and single-storey sand sheets and ribbons. misleading, as that stratigraphic interval micas (muscovite and biotite). A few grains Thicker sandstone units (thickness mostly contains very little coal. are composed of phyllosilicate minerals 5–20 m) of the Flying Eagle Canyon and represent altered grains such as feld- Formation are mostly multistorey trough Ash Canyon Formation spars. Sandstone contains small amounts cross-bedded sandstone (St), rare planar (revised) of matrix. Authigenic quartz overgrowths cross-bedded sandstone (Sp), and locally on detrital quartz grains are common; contain trough cross-bedded fine-grained Lithostratigraphy rarely, authigenic feldspar overgrowths are conglomerate (Gt) at the base. The thick also observed on detrital feldspar grains. sandstone units fine upward and grade In an unpublished thesis, Bushnell (1953, into other lithofacies, such as Sh, Sr, Sl, p. 17–22) named the Ash Canyon Mem-

Spring 2019, Volume 41, Number 1 21 New Mexico Geology ber of the Mesaverde Formation for Ash Ash Canyon Formation is beneath the Very thin to medium beds and lenses Canyon, a ravine at the south end of stratigraphically lowest volcaniclastic of pebbly sandstone and conglomerate are Elephant Butte Lake near Mescal Canyon. sandstone at the base of the José Creek observed in the upper 50–60 m of the Ash The first published mention of the unit is in Formation. Thus, the Ash Canyon Formation Canyon Formation. Clasts are composed Bushnell (1955a), who did not designate at this reference section is a sandstone-dom- of rounded granules and pebbles of gray a type section, although the unit is well inated unit with minor conglomerate, to black chert and clear to white quartz, exposed along the lower reaches of Ash lying between the mudrock-dominated quartzite, and siltstone rip-ups, with Canyon. As originally proposed, the Ash Flying Eagle Canyon Formation (below) and 1–5% silicious volcanic rock (aphanitic Canyon Member was restricted to a pebbly the volcaniclastic strata of the José Creek and gray), and traces of petrified wood sandstone interval 30 to 60 m thick at the Formation (above). In Sierra County, (Cikoski et al., 2017). Pebbles are rounded, top of the Mesaverde or Crevasse Canyon the Ash Canyon forms cliffs, ledges, and poorly sorted, and up to 5 cm in diameter. Formation. Without explicitly revising cuestas between the adjacent slope-forming The section at Mescal Canyon C (Fig. the definition, Mack and Seager (1993) units. A3.7) is 525 m thick and includes the upper expanded the Ash Canyon to include In general, the Ash Canyon Formation part of the Flying Eagle Canyon Formation, about 365 m of “predominantly tan, medi- consists of sandstone interbedded with the entire Ash Canyon Formation, and the um-grained, cross-bedded lithofeldspathic subordinate mudrock and siltstone. lower part of the José Creek Formation. sandstone interbedded with lesser amounts Sandstone is light-gray to pale-yellow on Here, the Ash Canyon succession is rela- of olive-gray mudstone. Chert-pebble con- fresh surfaces, weathering light brownish, tively coarse, containing a high proportion glomerate lenses within sandstone beds are yellowish, and pinkish gray. Grain size of sandstone and conglomerate. This may present locally, especially near the top of varies from very fine to very coarse, but reflect greater proximity to source area the unit.” Seager and Mack (2003) carried most of the sandstone is medium grained. than the Ash Canyon strata to the north. this change forward, and it was mapped in Based on hand specimens, composition Shale is brown, olive gray and olive green. the Cutter (Seager, 2007), Engle (Mack and was estimated at 60 to 90% quartz, 10 Shale intervals are mostly less than 10 m Seager, 1993), and Upham (Seager, 1995b) to 30% feldspar, and 10% or less lithic thick (~21 m maximum thickness). Trough geologic quadrangle maps. fragments and possible heavy minerals. cross-bedded sandstone (St) is by far the In this report, we apply the expanded Fresh pink to orange feldspar is prevalent, most abundant lithotype and is present in concept of the Ash Canyon Member as used but in some samples the feldspar is largely intervals up to 50 m thick. Less common by Mack and Seager (2003), and we elevate weathered to clay. However, samples are massive sandstone beds (Sm, 0.1–1.2 the unit in rank from a member to a forma- examined petrographically (see below) m thick), ripple-laminated sandstone tion. The Ash Canyon Formation is a thick contain more quartz, approaching quartz (Sr, 0.1–2 m thick), and horizontally interval of predominantly light-colored, arenite in composition. The sandstone laminated sandstone (Sh, 0.1–1m thick). quartzose, cross-bedded sandstone that has a sparkly appearance due to quartz? Conglomerate is relatively abundant. forms bold ridges, in contrast to the darker, overgrowths on the quartz grains; this Conglomerate in units 97–100 (Fig. A3.7) varicolored mudstone, siltstone, and lentic- feature aids identification of the unit in is mostly trough cross-bedded (Gt), and ular-tabular sandstone of the valley-form- the field. The rock is typically porous but rarely massive (Gm), consisting largely of ing Flying Eagle Canyon Formation. Fur- well indurated. extraformational siliceous pebbles. Units thermore, in the Ash Canyon Formation: Sandstone complexes of the Ash 110 and 111 are two massive conglomer- (1) sandstone intervals are typically several Canyon Formation are commonly sev- ate units (Gm) composed of chert pebbles. meters thick and are laterally continuous eral meters thick (as much as 15 m to Unit 113 is a sandstone containing lenses over 100–800 m; (2) mudstone-siltstone is the south, cf. Seager and Mack, 2003) of massive, mudstone-pebble conglomer- subordinate or subequal compared to these and are lenticular over 100–800 m on ate (Sm and Gm). sandstone intervals; and (3) the dominant strike (Cikoski et al., 2017). Sandstone is The upper 66–67 m of the Ash Canyon sand size is medium-grained. extensively cross-bedded (within medium Formation at the Mescal Canyon C Using these criteria, the Ash to very thick, tabular to lenticular beds), stratigraphic section are composed of Canyon Formation is readily identified on with common trough forms and tangen- three thick shale units and three sandstone the ground and aerial images. The older tial forests, although planar laminated conglomerate units. The shale units are definition of the unit (Bushnell, 1953) relied or massive beds are locally present; 11.2–14.5 m thick. The lower sandstone on the presence of quartz and chert pebbles paleoflow directions from the troughs are and conglomerate (units 115–118 in Fig. that are erratically distributed, and mostly toward the east-northeast (Cikoski et al., A3.7) is 19.1 m thick and composed of concentrated in its uppermost strata. 2017). The thick, ledge-forming sandstone trough cross-bedded sandstone (St) and Close to Ash Canyon, at the Mescal intervals of the Ash Canyon Member are trough cross-bedded chert conglomerate Canyon C section (Fig. A3.7), the Ash typically multistorey, whereas those in the (Gt). The sandstone unit in the middle (unit Canyon Formation comprises units 74 Flying Eagle Canyon Member tend to be 120) is 5.5 m thick, with massive, tabular through 124, and we consider this to be the single-storey (Seager and Mack, 2003). beds. The upper 5 m of the Ash Canyon principal reference section of the formation. Trough cross-bedding and cut-and-fill Formation is composed of mudstone At this section, the Ash Canyon Formation features are the most common sedimen- intercalated with trough cross-bedded is ~216 m thick. Its base is a thick succes- tary structures. Mudstone and siltstone pebbly sandstone to conglomerate (Gt) sion of sandstone and sparse conglomeratic of the Ash Canyon Formation are similar and coarse-grained, massive conglomerate sandstone that overlie relatively thick to mudstone and siltstone of the Flying (Gm). The latter conglomerate bed (unit (10 m or more) mudstone-dominated slopes Eagle Canyon Formation. Exposures of 124, 1.2 m thick) is composed of chert comprising the top of the Flying Eagle mudstone beds are generally confined to pebbles and is the top bed of the Ash Canyon Formation. The top of the canyon walls. Canyon Formation at this locality.

Spring 2019, Volume 41, Number 1 22 New Mexico Geology At the Fossil Forest section (Fig. Creek. This outcrop indicates a transition, Formation rests on Permian rocks and A3.6), the exposed thickness of the rather than an abrupt hiatus, between apparently was emplaced by large-scale Ash Canyon Formation is 208 m. The quartzose Ash Canyon sands to volcani- gravity sliding. Nearly all fossil wood in succession is composed of sandstone, clastic sands of the José Creek. the Ash Canyon Formation has weathered conglomerate, shale and siltstone. Shale free of rock matrix, suggesting that it is units are up to 6.4 m thick; some of the Paleontology and age derived from mudstone layers rather than shale units contain fossil logs. Covered sandstone. A few fossil stumps apparently intervals, which most likely also represent Petrified wood is widespread and locally in growth position have been observed, shale units, are up to 8.3 m thick. Sandstone abundant in the Ash Canyon Formation. but these are far less common than in the and conglomerate mostly forms thicker Segments of logs more than 50 cm across overlying McRae Group. Unfortunately, units (up to 33 m thick) that are composed and several meters long are not unusual the fossil wood illustrated and classified by of the following lithotypes: (1) conglom- (Fig. 11B). An enormous log, 27 m long Estrada-Ruiz et al. (2012a, b) is of no pre- erate as lenses within trough cross-bedded and 2 m across, was observed on the south cise biostratigraphic significance. sandstone or as thin, trough cross-bedded side of Walnut Canyon in the Fra Cris- Lucas et al. (2016) documented some (Gt) or massive (Gm) conglomerate beds; tobal Range (Hunter, 1986, first reported poorly preserved dinosaur footprints (2) trough cross-bedded sandstone, partly this log). This outlier of Ash Canyon from the Ash Canyon Formation near pebbly (St), is the most abundant lithotype; (3) sandstone with planar cross-bedding (Sp) is rare; (4) sandstone with low-angle cross-bedding (Sl) is rare; (5) horizontally laminated sandstone (Sh); (6) ripple-laminated sandstone (Sr); and (7) massive Ash Canyon sandstone, partly bioturbated (Sm) is Flying Eagle Formation rare. Trough cross-bedded sandstone Canyon Formation commonly is present as multistorey units, and rarely as single-storey units. A few fining-upward cycles are developed, grading from pebbly sandstone (St and Gt), into trough cross-bedded sandstone (St), and finally into horizontally laminated and B ripple-laminated sandstone (Sh, Sr), overlain by siltstone and shale. A good example A of a fining-upward cycle is the succession of units 64–70 (Fig. A3.6). Beginning with Bushnell (1953) and continuing through Seager and Mack (2003), previous workers regarded the contact between the Ash Canyon and the overlying McRae (José Creek) strata as unconformable. In the field, an obvious topographic and lithologic break separates light-colored, pebbly, ridge-forming D sandstone of the Ash Canyon from overlying darker, volcaniclastic, slope-forming sandstone, siltstone, and mudstone of the C José Creek. Clean exposures of the contact, however, are few. One of the best exposures observed is in the large west-trending arroyo 2.3 km northeast of Kettle Double Canyon Fm.? Top Butte (UTM 301029E, 3680720N). Sandstone at the base of this exposure is typical Ash Canyon, with quartz and chert granules. Overlying the sandstone is basement dark gray, carbonaceous mudstone about 3.5 m thick, above which is a sandstone bed, 3 m thick, that shares features of Ash E F Canyon and José Creek. This sandstone FIGURE 11. Photographs of selected outcrops of the Ash Canyon and Double Canyon formations. contains a high proportion of feldspar and A, Contact of Flying Eagle Canyon and Ash Canyon formations, Fossil Forest section. B, Fossil log in Ash Canyon Formation in Fossil Forest section. Note hammer for scale at center of image. C–D, volcanic lithic grains, but also has stringers Trough cross-bedded, silica-pebble conglomerate in the Ash Canyon Formation, Mescal Canyon of rounded chert and quartz granules, section. E, Siliceous conglomerate of Double Canyon Formation in Fra Cristobal North section. F, as in the Ash Canyon. The next higher Conglomerate of the Double Canyon Formation resting directly on Precambrian basement, northern sandstone is typical volcaniclastic José tip of the Fra Cristobals.

Spring 2019, Volume 41, Number 1 23 New Mexico Geology Ash Canyon. These are likely ornithopod Depositional environments members: the José Creek (lower) and the footprints, but of no precise biostrati- Hall Lake (upper). graphic significance. Like previous workers, we interpret the The McRae Formation is more than deposition of the Ash Canyon Formation 1 km thick, and its two members have Sedimentary petrography as totally nonmarine by fluvial processes. long been readily mapped at the scale of At the principal reference section in Mescal 1:24,000 (e.g., Lozinsky, 1985; Mack and Fine-grained conglomerate of the Ash Canyon (Fig. A3.7), the lower 19 m of the Seager, 1993; Seager, 1995b, c; Cikoski Canyon Formation is poorly sorted and Ash Canyon Formation is a succession of et al., 2017). Distinctive lithology and composed of subrounded to rounded clasts sandy and pebbly channel-fill sediments substantial thickness of the José Creek in a sandy matrix. Clasts include two types (lithofacies St, subordinately Sh), with rare and Hall Lake fully justify elevating these of chert: (1) the dominant type is volcanic intercalations of conglomerate (Gt, Gm). units to formations and the McRae to a chert, which appears mostly brownish These lithofacies types are combined into group. In addition, we describe a new unit under plane light and partly displays a the architectural elements CH (channel), of formation rank, the Double Canyon volcanic texture (spherulitic texture, small SB (sandy bedforms), and GB (gravel bars Formation, which overlies the Hall Lake phenocrysts of quartz); and (2) sedimen- and bedforms) sensu Miall (1996, 2010). Formation at the top of the McRae Group. tary chert is mostly clear under plane light Floodplain deposits are absent. This suc- and shows outlines of fossils such as shell cession probably represents deposits of a José Creek Formation fragments, spicules and other skeletal sand-dominated, braided fluvial system. grains (Fig. A5.4A–B). The sandy matrix The upper part of the Ash Canyon For- Lithostratigraphy of Ash Canyon conglomerate is composed mation, which is composed of alternating of mono- and polycrystalline quartz, rare thick mudstone units (floodplain deposits, As outlined by Bushnell (1953, 1955a, chert and detrital feldspars, a few grains of architectural element FF) and intercalated b), the José Creek Formation is the lower, phyllosilicate minerals (altered feldspars?), sandstone and conglomerate units (archi- drab-colored, sandstone and conglomer- and very rare phyllitic grains. tectural elements CH and SB) is interpreted ate-rich interval of the McRae Group (Figs. Sandstone of the Ash Canyon Formation as deposits of a meandering to anastomos- 12, A3.7–A3.10). The name refers to an (Figs. A5.3B–H, A5.4C) is mostly medium ing fluvial system (cf. Miall, 1996, 2010). intermittent stream that flows northwest to grained and moderately to well-sorted. Most At the Fossil Forest section (Fig. A3.6), Elephant Butte Lake (Fig. 2). We measured of the detrital grains are subrounded. The ~208 m of the Ash Canyon Formation is a principal reference section of the most common grains are monocrystalline exposed, and the deposits differ somewhat José Creek Formation at José Creek, quartz (including a few porphyry quartz from the section at Mescal Canyon. The where it is approximately 203 m thick grains), polycrystalline quartz and abun- succession is composed of alternating (Fig. A3.8). We also measured the lower- dant chert grains. Volcanic chert, which sandstone units (mostly lithofacies St, rare most part of the José Creek Formation at rarely displays ignimbrite texture and Sh, Gm, Gt), forming local fining-upward our Mescal Canyon C section (Fig. A3.7), spherulitic texture, is more common than sequences—we classify these as architec- and the uppermost part of the José Creek sedimentary chert. Detrital feldspars are tural elements CH (channel), SB (sandy Formation at our Kettle Top, McRae rare and include microcline, perthite and bedforms), and mudstone units that we Canyon, and Reynolds Canyon A sections untwinned grains. Granitic and volcanic classify as floodplain deposits forming (Figs. A3.9, A3.10). rock fragments are rare. Sedimentary architectural element FF (overbank fines). Estimates based on outcrop width and rock fragments (reworked siltstone) and Thinner sandstone units (<2 m) are inter- average dip at three sites in the southwest- metamorphic rock fragments composed of preted as minor channels and thicker sand- ern part of the Black Bluffs quadrangle mica and quartz with well-developed stone units (>2 m) as major channels of a yield José Creek Formation thicknesses of schistosity are very rare. A few grains com- sandy meandering to anastomosing fluvial approximately 128, 171, and 174 m. Sea- posed of clay minerals (altered feldspars?) system (see Miall, 1996, 2010). ger and Mack (2003) state a thickness of are present. The sandstone is cemented by According to Seager and Mack (2003), 170 m near Kettle Top Butte. Cikoski et al. quartz, which occurs as authigenic over- paleosols are common in the Ash Canyon (2017) report a thickness range of 80–130 growths on detrital quartz grains. Calcite Formation. The character of the paleosols— m. Thickness increases to a maximum cement is present in small amounts. The thin, gray A horizon, light colored E of about 200 m in the type area along José sandstone also contains small amounts of horizon, thick argillic B horizon—indicates Creek. Farther southeast, the José Creek matrix. well-drained soils that formed in a relatively steadily thins, pinching out entirely at Yoast The average composition of sandstone humid climate. Draw east of the central Caballo Mountains, of the Ash Canyon Formation is Q92F3L5 where the Hall Lake Formation overlies the (sublitharenite). Most of the sandstone McRae Group (change in rank) Ash Canyon Formation with an angular samples plot into the field of quartz arenite, unconformity (Seager and Mack, 2003). and subordinately into the field of subli- Kelley and Silver (1952) gave the name The José Creek Formation is generally tharenite. In the classification scheme of “McRae formation” to a thick succession non-resistant to erosion and underlies McBride (1963), most samples are sublitha- of sedimentary rocks that overlies the valleys and gentle slopes. Sandstone and renite and quartz arenite, rarely lithic sub- Ash Canyon Formation (our usage) in the silicified volcanic ash form low ledges. arkose. Thus, there is a mineralogical shift Cutter sag. The name refers to old Fort Good exposures of the José Creek can be from the Flying Eagle Canyon Formation McRae, a U.S. Army post that formerly found along most of the arroyos south of sandstones, which are mostly subarkoses, (1869 to 1876) stood on the south side of Black Bluffs that drain into Elephant Butte to the more mature quartz arenites of the McRae Canyon. Bushnell (1953, 1955b) Lake (Cikoski et al., 2017). Ash Canyon Formation. divided the McRae Formation into two

Spring 2019, Volume 41, Number 1 24 New Mexico Geology Lithologically, the José Creek resemble bedded chert. These beds are Reynolds Canyon A section (Fig. A3.10), Formation is composed of non-fissile white to light brown, yellow, or purple. sandy siltstone beds are present just below siltstone and mudstone interbedded The cherty beds exhibit a dull or vitreous the Hall Lake Formation that contain in roughly equal proportions with luster and are generally densely jointed. abundant fossils of plant foliage. volcaniclastic fine- to coarse-grained The chert-like rock is present in individual The José Creek and Hall Lake forma- sandstone, almost all beds exhibiting an layers less than 1 m thick and in thicker tions are differentiated chiefly by the drab olive color. Conglomerate and silicified intervals interbedded with siltstone and green, brown, and olive-colored mudstone volcanic ash are minor, but distinctive mudstone. Lozinsky (1985) and Seager and of the former in contrast with the maroon components, and the proportion of Mack (2003) observed shards of volcanic and purplish mudstone of the latter. conglomerate increases to the south. glass in thin sections, indicating that these It is likely that this reflects the climate Mudstone and siltstone are dominantly layers consist of silicified volcanic ash. change from relatively wet (José Creek) dark green, olive, and brownish gray. Red Along Cañon del Muerto southeast to relatively dry (Hall Lake) indicated by colors are rarely seen, and where present, of old Fort McRae (UTM 303000E, the paleosols (Buck, 1992; Levron, 1995; may be the result of hydrothermal alter- 3672950N), large sandstone dikes and Seager and Mack, 2003), but more study ation. Mudrocks are massive and display small faults are present in José Creek of the color change is needed to confirm pedogenic features, including root traces strata. The largest dikes are up to 15 cm this inference. South of Kettle Top Butte, and blocky ped structure. Pedogenic wide and crosscut at least 3 m of strata. the José Creek-Hall Lake contact appears carbonate nodules are generally absent. The filling is dominantly fine sandstone, unconformable, as the Hall Lake has a Levron (1995) and Buck and Mack (1995) containing scattered coarse grains and basal conglomerate that contains rounded classified most José Creek paleosols as small granules. cobbles as large as 30 cm in diameter (Fig. Argillisols and attributed them to weath- At the principal reference section A3.9, Kettle Top section, unit 5). North of ering under a humid to subhumid climate. (Fig. A3.8), the José Creek Formation Kettle Top Butte, the formation contact is Mudstone and siltstone layers range up to is 203 m thick and is mostly siltstone either a minor disconformity or a transition about 3 m thick and commonly contain or shale (64% of the measured section), through an interval of 3 m or less. In the thin, lenticular interbeds of sandstone. with less sandstone (29%), conglomer- south bank of Reynolds Canyon just above Sandstone of the José Creek Formation ate and conglomeratic sandstone (5%), its confluence with Flying Eagle Canyon, displays various shades of gray, green, and volcanic ash and silcrete (2%). the base of a lens of coarse sandstone at bluish gray, brown, and brownish gray, The most abundant lithotype is silty the base of the Hall Lake is slightly scoured and tends to become darker on weathered mudstone to siltstone, and subordinately into uppermost José Creek mudstone. surfaces than in fresh exposures. Most mudstone (lithofacies Fsm). Individual Beyond the pinch-out of the sandstone lens, sandstone is weakly to moderately indu- siltstone-mudstone units are up to 15 the contact continues to be sharp but par- rated and erodes to low, rounded outcrops. m thick. Intercalated are thin beds (<1 allel to bedding. Excellent exposures of the Grains are very fine to medium and poorly m thick) of trough cross-bedded (St), contact are also present near the northern sorted. Sandstone bodies are typically 2 to horizontally laminated (Sh) or massive edge of the Elephant Butte quadrangle in a 9 m thick and laterally continuous over sandstone (Sm). Thicker sandstone units west-trending arroyo 1.7 km east to north- tens to hundreds of meters, and bedding are also present and composed of trough east of Kettle Top Butte. In these exposures, within these bodies is lenticular to tabu- cross-bedded sandstone (St) and subor- greenish-gray and purplish-gray mudstone lar and thin to thick. Wavy lamination, dinate horizontally laminated sandstone layers alternate through an interval about cross-bedding, scour and fill features are (Sh). Conglomerate is massive (Gm) or 3 m thick. developed in some layers. In contrast to all trough cross-bedded and contains clasts older Cretaceous units, the sand is com- mostly of volcanic rocks (Gt). Minor Paleontology and age posed dominantly of lithic grains derived lithotypes are a limestone interval (Fig. from volcanic rocks, together with feldspar, A3.8, unit 25) composed of wavy bedded Fossil foliage and wood are locally common and little or no quartz. Some sandstone and nodular limestone (lithofacies P), thin in the José Creek Formation. During our beds of the José Creek Formation contain silcrete beds, and a thin volcanic ash layer investigation, plant remains we observed scattered, rounded and well-rounded containing fossil leaves. include roots, stems, and foliage. Silicified granules, pebbles, and, rarely, small At Mescal Canyon C, we measured wood was also found, but other than a cobbles (up to 15 cm in diameter). These the lowermost José Creek Formation stump in the José Creek principal reference are predominantly intermediate to basic (Fig. A3.7). Here, it is composed of olive- section (Fig. 12D), none of it was in place. volcanic and intrusive rocks, but in some green mudstone (2.2–13.2 m thick beds), Upchurch and Mack (1998) documented samples include clasts of intraformational intercalated with trough cross-bedded fossil plants from the José Creek Forma- siltstone, sandstone, and impure carbonate sandstone (St; 1.2 and 5.8 m thick) and tion. These authors used foliage to identify rock. As Bushnell (1953, 1955a, b) noted, horizontally laminated (Sh) to massive 40 to 50 species of ferns, conifers, cycads, overall proportion of conglomerate and (Sm) sandstone (3.1 m thick). These sand- and angiosperms; wood features were used the size of clasts in José Creek conglom- stones are volcanic litharenites. to identify conifers, dicots, and monocots erate increases toward the south, with We also measured the upper 5 to (likely palms). Estrada-Ruiz et al. (2012a, boulders as large as 1 meter in diameter 10 m of the José Creek Formation b) identified 10 types of dicots, three types present near the south end of Elephant at our Kettle Top, McRae Canyon, and of monocots, and seven types of conifers Butte Lake. Evidently, a volcanic center Reynolds Canyon A sections (Figs. A3.9, from wood in the José Creek Formation. was located nearby. A3.10). At these locations the uppermost Lozinsky et al. (1984) and Wolberg et The upper part of the José Creek José Creek strata are mostly olive-colored al. (1986) reported dinosaur fossils from Formation contains layers of rock that volcanic-litharenite sandstones. But at the the José Creek, but, as best as we can deter-

Spring 2019, Volume 41, Number 1 25 New Mexico Geology mine, all of these fossils actually came from José Creek Formation, given correlation of Basal sandstones from the José the Hall Lake Formation. For example, we the volcaniclastic strata of the José Creek Creek section (Fig. A5.4D–F) differ sig- relocated and collected a sauropod femur to the Copper Flat volcanic complex, nificantly in composition from the lithic that Lozinsky et al. (1984, fig. 6) illustrated. which is at least in part of Campanian age arenites typically encountered in the They identified the stratigraphic level as (see later discussion). José Creek Formation, however, and the José Creek Formation, but we determined dominant grain type is monocrystalline it to be Hall Lake Formation (Fig. A3.11, Sedimentary petrography quartz. The sandstone also contains NMMNH locality 11834). many chert grains of volcanic origin, and Amato et al. (2017, fig. 4) reported In a petrographic study of the José Creek many detrital feldspar grains, including U-Pb ages from the José Creek Formation Formation based on 8 samples, Hunter potassium feldspars (mostly untwinned, in the Cutter sag (southwestern part of the (1986) reported 58 to 76% lithic grains, a few perthitic grains) and plagioclase Engle quadrangle: see Seager and Mack, 24 to 40% feldspar, and 0 to 3% quartz. displaying polysynthetic twinning. 2003, fig. 49). In ascending stratigraphic This composition places the sandstone Many of the feldspar grains are altered. order, the reported weighted means are samples into the field of lithic arenites. Minor grain assemblages include 74.9 ± 0.7 Ma, 74.6 ± 0.6 Ma and 75.2 Lithic grains were 97 to 100% of volca- volcanic rock fragments of acidic to ± 1.3 Ma. These ages are laser abla- nic origin, and the feldspar grains were intermediate composition, chert grains tion-inductively coupled plasma mass dominantly plagioclase. A single sam- displaying spherulitic texture, granitic spectrometry ages (LA–ICPMS), which ple from the base of the José Creek rock fragments containing coarse-grained are less precise than isotope dilution- Formation contained 21% quartz quartz and feldspar, and fine-grained thermal ionization mass spectrometry and only 4% feldspar. Some of that schistose metamorphic rock frag- (ID-TIMS) ages (Bowring et al., 2006; sand was likely recycled from the ments composed of quartz and micas. Schoene, 2014). Nevertheless, they are underlying Ash Canyon Formation Detrital muscovite, biotite, and chlorite are Campanian ages, and thus likely a reason- or reflects gradation between the very rare. A few grains composed of fine- able approximation of the age of part of the Ash Canyon and José Creek lithosomes. grained phyllosilicate minerals are present

A C

stump

B D FIGURE 12. Photographs of selected outcrops of the José Creek Formation. A, Overview of lower-middle part of the José Creek principal reference section. B, Contact of José Creek and Hall Lake formations (staff held at contact) in Reynolds Canyon. C, Sandstone bed in principal reference section of José Creek Formation. D, Fossil stump in principal reference section of José Creek Formation.

Spring 2019, Volume 41, Number 1 26 New Mexico Geology that probably represent altered feldspar McRae Formation. The name refers to carbonate nodules (Fig. 13B), are inter- grains. Accessory minerals are zircon, Hall Lake, which was formerly the official preted as pedogenic features associated titanite, tourmaline, and opaque grains. name for Elephant Butte Lake (Reser- with paleosols. Inclined carbonate stringers The sandstone contains small amounts voir). Bushnell (1955a, p. 15) imprecisely (along slip fractures) and vertical cylinders of matrix and blocky calcite cement that located the type section “on the east shore (after roots) are also developed (Fig. 13C). randomly replaces detrital feldspar grains. of the lake, northeast of Elephant Butte Excellent exposures of such features are Locally, authigenic quartz overgrowths and south of McRae Canyon.” Bushnell present along Flying Eagle Canyon about are present on detrital quartz grains. (1953) described the section, which mea- 600 m below the junction with Reynolds The average composition of sand- sures approximately 490 m thick, with Canyon. Buck and Mack (1995) classified stones of the basal José Creek Formation the base under water and the top faulted paleosols of the Hall Lake as calcisols and at the José Creek section is Q81F6L13 and against older units. With reference to vertic calcisols, suggesting a climate more are sublitharenite to subarkose, using the the geologic map of Lozinsky (1985), arid than that which prevailed during José classification scheme of Pettijohn et al. Bushnell’s type section probably extends Creek deposition, possibly accounting for (1987). Most samples plot into the field of northwest from near the mouth of Beaver the reddish color of the mudstones. sublitharenite, and rarely into the fields of Canyon through the area known as “The Sandstone in the Hall Lake Formation lithic subarkose and subarkose, following Jungles.” Aerial imagery suggests that this displays various shades of green, blue, the classification scheme of McBride(1963) . is a well-exposed, gently dipping section purple, and reddish gray. In the upper part with no significant internal faults. of the formation, the prevalent color is Depositional environments Another continuous section, mod- medium to dark gray with a purplish cast. erately dipping and without faults, is Cikoski et al. (2017) describe channel fills Deposition of the José Creek Formation present east of Double Canyon and south in the Black Bluffs quadrangle as typically was by fluvial processes (Bushnell, 1953; of Flying Eagle Canyon. We did not mea- single storey (1 to 3 m thick) but locally Wallin, 1983; Seager and Mack, 2003). sure the section, but a minimum thickness multistorey and 4–6 m thick; these consist The siltstone-mudstone facies represents of approximately 730 m was obtained of medium to thick, tabular to lenticular floodplain deposits (overbank fines; archi- through geometric construction. A steeply beds that are internally massive (Sm), tectural element FF). Thin sandstone beds dipping section, northwest of Flying Eagle horizontal-planar laminated (Sh), or represent small channel fills (lithofacies St) Canyon near its mouth, also is at least cross-bedded (tangential foresets, up to and sheetflood deposits (lithofacies Sm, 700 m thick. In this area, the Hall Lake 20 cm high, with local trough forms; St). Sh), and may be assigned to architectural Formation has conformable lower and We’ve found that the thicker sandstone element SB (sandy bedforms). Seager and upper contacts with the José Creek and units (mostly 1–8 m thick) are mostly Mack (2003) interpret the thin intercalated Double Canyon formations, respectively. composed of trough cross-bedded mul- sandstone beds as crevasse-splay deposits. Southeast of the type area, the Hall Lake tistorey sandstone (St), subordinately of Thicker sandstone units and, sub- thins markedly because of truncation of the planar cross-bedded (Sp) and horizontally ordinately, massive, and cross-bedded upper part beneath the Eocene Love Ranch laminated sandstone (Sh). Bedding varies conglomerate (Gm, Gt), represent major Formation. Thus, at Yoast Draw east of from thin to very thick. Some sandstone channels composed of multistorey the central Caballo Mountains, Seager and beds are nearly massive, and these rocks crossbed sets (St). The intercalated thin Mack (2003) reported that the Hall Lake is exfoliate like a plutonic rock. Large-scale limestone unit is interpreted based on field less than 15 m thick. cross-bedding is faint to prominent, observations (it includes rhizoliths) as We did not measure a “complete” depending on weathering. Grain size var- pedogenic carbonate (lithofacies Pc), and section of the Hall Lake Formation, but ies from fine to very coarse, with pebbles the silcrete beds represent altered volcanic instead measured sections of the lower 200 to small cobbles locally present, and is ash beds (siliceous tuffs of Seager and m or less at Kettle Top (Fig. A3.9), McRae mostly medium to very coarse grained Mack, 2003). Whether the ash was depos- Canyon (Fig. A3.9), Reynolds Canyon on the Black Bluffs quadrangle (Cikoski ited directly by the wind or transported by (Fig. A3.10), and Cottonwood Canyon et al., 2017). Clastic dikes were noted in water is not certain. (Fig. A3.11). We also measured the upper several outcrops. The José Creek Formation probably 25 m of the Hall Lake Formation at the Based on field observations, sandstone represents deposits of a sandy braided to type Double Canyon section (Fig. A3.12). of the Hall Lake is feldspathic litharenite, anastomosing fluvial system with thick At these sections and elsewhere, the Hall similar to sandstone of the José Creek floodplain deposits that likely accumulated Lake Formation consists largely of reddish Formation. Quartz varies from zero to a on the distal edge of a volcaniclastic apron brown to maroon (locally light green) few percent of rock volume. However, surrounding one or a cluster of volcanoes mudstone (Fig. 13A), with subordinate based on thin-section study, Hunter (1986) to the southwest. According to Seager and lenticular sandstone tongues (Fig. 13D) reported Hall Lake sandstone to consist of Mack (2003), José Creek paleosols indicate that are locally conglomeratic (Fig. 13E), 43 to 66% lithic grains, 13 to 30% feld- deposition under subhumid climatic condi- and very sparse silicified volcanic ash. In spar grains, and 15 to 27% quartz. One tions (also see Buck, 1992; Levron, 1995). the Black Bluffs quadrangle, the sandstone of Hunter’s samples contained 55% quartz bodies may be up to 30–70 m thick and and only 29% lithic fragments. According Hall Lake Formation extend over 20–150 m lateral distances to Hunter, lithic grains are mostly of volca- (Cikoski et al., 2017). The mudstone inter- nic origin, but metamorphic and plutonic Lithostratigraphy vals are up to approximately 23 m-thick rock fragments are more abundant relative beds that are soft and deeply weathered, to José Creek sandstone. Bushnell (1953, 1955a) named the Hall Lake forming low, hummocky terrain. Blocky Local conglomeratic strata are typ- Member as the upper of two divisions of the structure together with slickensides and ically composed of thin lenticular beds

Spring 2019, Volume 41, Number 1 27 New Mexico Geology that are 0.6–2.2 m thick, and massive or any other genus. Subsequent publica- the apparent conflict between the U-Pb age or trough cross-bedded (Gm, Gt). South tions on vertebrate-fossil assemblages of and dinosaur biostratigraphy is an ID-TIMS of Kettle Top, the Hall Lake Formation the Hall Lake Formation include: Loz- date from the Hall Lake tuff (to possibly has a basal conglomerate that contains insky et al. (1984), Wolberg et al. (1986), estimate a more precise numerical age), and rounded cobbles as large as 30 cm in Gillette et al. (1986), Lucas et al. (1998a, possibly more biostratigraphic data. diameter. The cobbles consist of white, 2017a, 2017b), Sullivan et al. (2005), Suazo The presence of latest Cretaceous gray, and pink quartzite; pink and red et al. (2014), Sullivan and Lucas (2015), dinosaur fossils in the lower part of the porphyritic rhyolite, gray to pink granite, Dalman and Lucas (2017), and Lichtig and Hall Lake Formation suggests that the and greenish-gray, intermediate volcanic Lucas (2017). upper part of the formation may be Paleo- rocks. Sparse conglomerate layers are Fossil turtle and dinosaur bones are cene in age. Because it contains a succes- also present higher in the Hall Lake present 24, 29, and 32 m above the base sion of paleosols, suggesting extended throughout the study area. Intermediate of the Hall Lake Formation at the McRae episodes of soil development, this unit and mafic volcanic rocks continue to Canyon section, in the upper part of the may have accumulated over a long interval dominate, but clasts of red to pink granite, Kettle Top section, and in the Reynolds of time. chert, quartzite, and quartz become Canyon A section (Figs. 13F, A3.9, A3.10). increasingly common toward the top These stratigraphic sections make it pos- Sedimentary petrography of the formation. This may indicate a sible to put many of the vertebrate fossil petrographic trend of gradation into the localities in the Hall Lake Formation into Sandstone and conglomerate of the Hall overlying Double Canyon Formation. stratigraphic context, and the bulk of the Lake Formation (Figs. A5.5–A5.6) is dis- Some Hall Lake units display a fin- assemblage (including the most identifi- tinctive petrographically. Most conglom- ing-upward trend, starting with Gt, grad- able dinosaur fossils) comes from low in erates contain a mixture of intermediate ing into St and finally into Sh (Fig. 13D). the formation, 24–141 m above its base volcanic types with 0–25% siliceous clasts Another common lithofacies consists of (Figs. A3.9, A3.10). This interval yields a and 0–10% granite (based on Cikoski et thin (mostly 20–40 cm) carbonate beds jaw of Tyrannosaurus rex (Fig. A6.5; 43 al., 2017). Intraformational conglomerate (pedogenic calcretes), which are partly m above the base), partial skeletons of a is poorly sorted, clast supported, and nodular and sometimes contain root new ceratopsian genus originally assigned consists of partly recrystallized carbon- traces (lithofacies P). to Torosaurus (24–43 m above the base), ate clasts (most likely derived from the Without specifying localities, Loz- and a femur of the sauropod dinosaur Ala- reworking of paleocaliche beds), some insky (1985) reported layers of white to mosaurus (141 m above the base). Sullivan containing a few small quartz grains. light red, silicified volcanic ash in the Hall and Lucas (2015) referred to this vertebrate Sand-sized detrital quartz grains (mostly Lake Formation in the Elephant Butte assemblage as the Armendaris local fauna, monocrystalline quartz), and a few detri- quadrangle. We observed no such lithol- and, like previous workers (Lozinsky et al., tal feldspar grains are present. The con- ogy in the Hall Lake, and suspect that the 1984; Wolberg et al., 1986; Gillette et al., glomerate is cemented by calcite. Pebbly silicified layers reported by Lozinsky are 1986; Lucas et al., 1998a), considered it sandstone is moderately to poorly sorted, in the younger Double Canyon Formation to be of late Maastrichtian (Lancian) age. the sand grains are angular to rounded, (see below). This is because records of Tyrannosaurus and is cemented by calcite. The contact between the Hall Lake and Alamosaurus are of Lancian age in Coarse-grained sandstone of the Hall Formation and the overlying Double Can- Texas, Utah, and the San Juan Basin of Lake Formation is moderately sorted yon Formation was mapped at the base of northwestern New Mexico (Lucas et and composed of monocrystalline quartz the lowest significant greenish, bluish, or al., 2012). (including volcanic quartz), some poly- olive-gray mudstone or conglomerate bed, The only other fossils we observed in crystalline quartz, many detrital feldspars, in contrast to the prevalent dark reddish the Hall Lake Formation are large vertical, volcanic rock fragments, rare granitic and purplish- gray mudstone of the Hall meniscate burrows we assign to Taenid- and metamorphic rock fragments, and Lake. The contact appears to be grada- ium. These were encountered in sandstone a few chert grains (Fig. A5.5A–C). The tional and conformable near the type area at two separate localities in Reynolds Can- detrital feldspars include plagioclase and of the Hall Lake Formation. yon in the lower 100 m of the formation potassium feldspar, are mostly altered (Fig. A3.10). to different degrees, and are partly Paleontology and age Amato et al. (2017, fig. 4) reported a replaced by calcite. Some large volcanic U-Pb age of 73.2 ± 0.7 Ma on a tuff bed rock fragments are composed of zoned Fossils that represent several genera of about 10 m above the base of the Hall plagioclase phenocrysts with hypidiomor- dinosaurs from the lower part of the Lake Formation. However, this Campa- phic texture, partly altered and embedded Hall Lake Formation indicate that these nian age is from a tuff stratigraphically in fine-grained volcanic matrix (Fig. rocks are latest Cretaceous (Maastrich- just a short distance below late Maas- A5.5D–H). Some phenocrysts are altered tian or Lancian) in age, which is ~66 to trichtian dinosaur fossils, so we question to chlorite (originally probably hornblende 68 Ma (Lucas et al., 2012). Lee (1907b) its reliability. In particular, the MSWD or pyroxene). first reported fossils from what later was (mean square of weighted deviates) value Fine- to medium-grained sandstone named the Hall Lake Formation, consist- of 1.7 for the dated sample reported (Fig. A5.6F–H) is moderately to well-sorted. ing of dinosaur bones and a skeleton of by Amato et al. (2017, p.1218) suggest The grains are angular to subangular in “Triceratops.” A few bones of this skeleton, that the analytical data the weighted fine-grained sandstone and subangular preserved in the Smithsonian collection mean was calculated from are too scat- to subrounded in medium-grained sand- (Fig. A6.4), are only diagnostic of a large tered given the reported uncertainty (e.g., stone. The sandstone contains abundant ceratopsian dinosaur, not of Triceratops Schoene, 2014). What is needed to resolve monocrystalline quartz (including volcanic

Spring 2019, Volume 41, Number 1 28 New Mexico Geology quartz), a few polycrystalline quartz Double Canyon Formation Hall Lake Formation (Seager and Mack, grains, abundant detrital feldspars, a few (new) 2003). Characterized by conglomerates granitic rock fragments and a few volcanic that are locally boulder-bearing and red rock fragments composed of feldspars. Lithostratigraphy to gray sandstone and mudstone, the Love The detrital feldspar fraction includes Ranch is markedly dissimilar to the Dou- many untwinned feldspar grains (probably In the vicinity of Black Bluffs and Kettle ble Canyon. Although it is confined to a orthoclase), plagioclase, rare microper- Top Butte, between the southern end of small geographic area, the Double Canyon thitic grains and rare microcline. Volcanic the Fra Cristobal Range and Elephant Formation is mappable (Fig. A4.1; also see rock fragments and volcanic chert grains Butte Lake, a previously undescribed Cikoski et al., 2017) and provides import- are common constituents. Schistose meta- succession of sedimentary rocks overlies ant insights into the tectonic evolution of morphic and granophyric rock fragments the Hall Lake Formation. At least 425 m the area (see later discussion). are very rare. A few volcanic chert grains thick, these strata include mudstone that is We have identified the Double Canyon display the spherulitic texture typical of mostly greenish, bluish gray, or olive gray. Formation in three separate fault blocks rhyolitic volcanic rocks. Detrital musco- Sandstone bodies are commonly arkosic (Fig. A4.1). The first is the south-dipping vite and chlorite are rare, and biotite is and relatively coarse-grained, locally bear- hogback that contains the type section. The very rare. The sandstone contains many ing silicified logs, but also include variable second fault block, immediately northwest opaque grains. A few detrital grains are volcaniclastic fragments. Conglomerate of the first, has synclinal structure; here the almost completely altered to clay miner- beds are of mixed lithologies but generally base of the Double Canyon Member may als (originally feldspars?). Volcanic rock contain more granitic clasts than seen in intertongue with the underlying Hall Lake fragments contain abundant feldspar and the Hall Lake Member. Locally, there are Member. The third outcrop area, called a few quartz phenocrysts. The sandstone prominent beds of silicified volcanic ash. “McRae Forest” because of the abundance is cemented by coarse poikilotopic calcite; These beds show some resemblance to of fossil wood, is northeast of Black Bluffs locally, some matrix and diagentic chlorite the José Creek Formation, and Lozinsky and 3 to 4 km north of the other expo- are present. (1985) mapped them as such near the sures. Here, the base of the Double Canyon Most sandstones of the Hall Lake northern edge of his study area. Lozinsky is in fault contact with older rocks, and the Formation plot into the field of lithic mapped the contacts of what he identified upper contact is concealed by Quaternary arenite, and a few sandstone samples as the José Creek Formation (Member) alluvium (Fig. A4.1). plot into the field of arkose. The average as faulted, but we found clean exposures At the type section, the Double Can- composition is Q45F24L31 (lithic arenite). demonstrating that the previously unde- yon is 131 m thick, with the upper contact Most samples are classified as felds- scribed strata overlie the Hall Lake with faulted (Fig. A3.12). At the McRae Forest pathic litharenite, and rarely as lithic a normal, depositional contact (Fig. A4.1). section (Figs. A4.1, A3.13), the Double arkose, according to the classification of The level of Elephant Butte Lake has Canyon is about 310 m thick, with the McBride (1963). dropped substantially since the 1980s, lower contact faulted and the upper con- revealing outcrops that were under water tact covered by Quaternary sediments. Two Depositional environments when Lozinsky conducted his field work. prominent, ridge-forming intervals of chert The name Double Canyon Formation that are present in the southern area (type All workers have suggested that deposition is proposed for these previously unde- section) are absent in the northern area of the Hall Lake Formation was wholly scribed strata. The name refers to Double (McRae Forest). The higher of the silicified nonmarine and involved fluvial processes Canyon, a two-forked ravine near the intervals (a single bed of chert) lies about (Hunter, 1986; Buck, 1992; Buck and eastern shore of Elephant Butte Reservoir 115 m above the base of the formation. Mack, 1995; Levron, 1995; Seager et al., (Fig. A4.1). The type section is a south-fac- Thus, assuming that the silicified layers are 1997; Seager and Mack, 2003). The mud- ing hogback ridge 1.6 km north-northeast faulted out of the section at McRae Forest, stone facies of the Hall Lake Formation of Kettle Top Butte at the northern edge of the Double Canyon Formation has a min- is interpreted as floodplain deposits. Thin the Elephant Butte 7.5-minute quadrangle imum composite thickness of 425 m along sandstone and conglomerate intercala- (Figs. 14, A4.1, A3.12). From about 3 km the eastern side of Elephant Butte Lake. tions represent small channel fills (St, Gt) north-northeast of the type section, one The Double Canyon Formation is and sheetflood deposits (Sh, Sm). Thicker can walk southward through a continu- definitely absent northeast of the Caballo sandstone units are interpreted as major ous, gently dipping succession from the Mountains, where the Eocene Love Ranch channels (multistorey, cross-bedded sand- Ash Canyon Formation through the José Formation truncates the Hall Lake For- stone and conglomerate) forming architec- Creek and Hall Lake formations to the mation. No information on the Double tural element CH (channel) and SB (sandy Double Canyon Formation (Fig. A4.1). Canyon is available from the borehole logs bedforms). Wherever we have observed the top of the that we examined (the Double Canyon For- The Hall Lake Formation represents Double Canyon, it is either in fault contact mation was not a recognized unit when the deposits of an extensive muddy flood- with older units (as it is at the type section) logs were interpreted). The Beard Oil #1 plain with minor and major channels of or concealed by Quaternary alluvium. Jornada del Muerto test, drilled about 11 a braided to anastomosing fluvial system. We recognize the Double Canyon km southeast of Engle, possibly penetrated Red mudstones and common pedogenic as a new formation because it is distinct as much as 1070 m of McRae Group, but carbonates indicate deposition under rela- from the older Hall Lake and from any formations were not differentiated, and tively dry climatic conditions (Buck, 1992; younger Cenozoic formation known in part of the thickness could include Love Buck et al., 1992; Buck and Mack, 1995; the region. In the Caballo Mountains Ranch and younger units. No samples are Seager and Mack, 2003). to the south, the Eocene(?) Love Ranch available for this drill hole. Formation unconformably overlies the

Spring 2019, Volume 41, Number 1 29 New Mexico Geology The Double Canyon Formation is moderately sorted. Small cobbles are rarely lower silicified unit is about 30 m lower in composed of interbedded mudstone, present. In general, sand is dominantly the section and averages about 6 m thick, siltstone, sandstone, conglomerate, and medium- to coarse-grained, subangular to and in our measured section is two distinct bedded chert. These rocks have some subrounded, moderately to well-sorted, beds (Fig. A3.12, units 37 and 39). Colors features in common with older parts of and composed of feldspar, quartz, and are primarily light gray, pink, or yellowish the McRae Group, but other features are minor volcanic lithic grains; up section, orange, and some layers are greenish to unique to the Double Canyon Formation. sand becomes less arkosic, with more vol- olive. Some of the rock is dense and breaks Chief among the unique features are: caniclastic lithic grains (description slightly with conchoidal fractures. Other layers are (1) a greater proportion of quartz in the modified from Cikoski et al., 2017). distinctly granular and may be, at least in sandstone, (2) coarse conglomerate with Two intervals of chert are present in part, silicified siltstone and sandstone. The common pebbles and cobbles of granite the Double Canyon Formation in the type upper unit displays a channel geometry, mixed with volcanic and silicic clasts, and section. The upper interval (Fig. A3.12, unit with the lower contact truncating beds (3) thick chert intervals and layers that 44; Fig. 14C) is a single bed 1.3 m thick beneath. The lower unit does not have a form ridges. and caps the north to south hogback just channel form and contains interbeds of olive In general, the Double Canyon west of the fork of Double Canyon, and to greenish-gray siltstone and mudstone. Formation consists of pale brown to also holds up a south-dipping hogback Overlying the lower chert beds at Dou- white to light gray sandstone and peb- at the Double Canyon type section. The ble Canyon is an interval of coarse, pebbly bly sandstone beds, interbedded with greenish, bluish, and olive-gray mudstone and siltstone. Purplish and reddish-gray hues are subordinate. These colors may chert layer explain why Lozinsky (1985) mapped strata in the Double Canyon type area as José Creek. Also, the Hall Lake–Double Canyon contact was submerged beneath Elephant Butte Reservoir at the time of Lozinsky’s mapping. Mudstone and siltstone of the Double Canyon Formation are non-fissile and non-resistant to erosion. Thin sandstone interbeds are common, but carbonate nodules are sparse. Sandstone in the lower part of the Double Canyon Formation is A mostly light gray, light brownish gray, or greenish gray. These sands are relatively coarse-grained, poorly sorted, and composed of roughly equal proportions of quartz, feldspar, and lithic fragments. Quartz content is as high or higher (commonly about 20% to 40%) than many sandstones elsewhere in the McRae Group. Many of the sandstone beds are conglomeratic and contain 20–30% quartz granules and pebbles together with subrounded to well-rounded clasts of granitic B C rocks, volcanic rocks, chert of various colors, and mudstone rip-up clasts. Large silicified fossil logs and stumps are present (e. g., Fig. 14D–E). Amalgamated channel-fill complexes are as much as 7 m thick. Individual sand- log stone channel fills are thick to very thick, display tangential foresets up to 20 cm tall, and, locally, trough forms or horizontal-planar laminated beds. There are also tabular beds that are internally cross-stratified or horizontal-planar bedded (laminated to 30 D E cm thick) (Cikoski et al., 2017). FIGURE 14. Photographs of selected outcrops of the Double Canyon Formation. A, Overview of Pebbly sandstone is commonly in very most of type section. View is looking southwest at ridge approximately 70 m high. Light-colored thin to medium, tabular to lenticular beds, beds at crest of ridge are chert layers, units 37, 39, and 44 in the measured section (Fig. A3.12). B, some showing low-angle cross-stratifica- Silica-pebble conglomerate. C, Volcanic ash (silcrete) bed. D, Fossil log near base of section. E, Fossil tion. Pebbles are subangular to rounded and stump in Double Canyon Formation at McRae Forest section.

Spring 2019, Volume 41, Number 1 30 New Mexico Geology sandstone that weathers to large, rounded Paleontology and age Mudstone facies of the Double outcrops. This sandstone is composed Canyon Formation are interpreted as largely of feldspar, with a smaller propor- Fossils from the Double Canyon Forma- floodplain deposits. An intercalated thin, tion of lithic grains and less than 10% tion observed in this study are limited massive sandstone bed (Fig. A3.13, unit quartz. Pebbles include basalt, porphyritc to terrestrial plant material (wood), 96) probably formed during a sheetflood volcanic rocks, chert, and quartz. Large- including some of the fossil wood docu- event. The thicker conglomerate-sandstone scale, high-angle crossbeds are prominent. mented by Estrada-Ruiz et al. (2012a, b) units are interpreted as architectural ele- Interbedded with the sandstone is greenish and attributed by them to the José Creek ment CH (channel; lithofacies Gt, St), in to bluish-gray mudstone. Formation (Fig. 14E). Unfortunately, these combination with element SG (sediment At the type section of the Double Can- fossil woods are of no precise biostrati- gravity-flow deposits including debris yon Formation (Fig. A3.12), the following graphic value. Thus, the age of the Double flow; lithofacies Gmm) and element SB lithofacies types are distinguished: (1) Canyon Formation cannot be determined (sandy bedforms; lithofacies St, Sh, Sm). thick, olive to gray mudstone successions, with available data. The chert beds in the Double Canyon type up to 17 m thick (lithofacies Fm); (2) a section are most likely silicified volcanic single, thin, massive sandstone bed (Sm) Sedimentary petrography ash beds, though some textures and struc- intercalated in mudstone (Fig. A3.12, unit tures suggest that some fluvial working or 46); (3) thicker sandstone conglomerate Sandstone of the Double Canyon Forma- reworking of siliceous material may have units consisting of massive (lithofacies tion is fine- to coarse-grained and partly been involved in their deposition. Gmm and Gm) and trough cross-bedded pebbly. The sandstone is moderately sorted, conglomerate (Gt), trough cross-bedded and the pebbly sandstone is poorly sorted. Northern Fra Cristobal sandstone (St; most abundant lithofacies), The grains are subangular to subrounded. Mountain Outcrops rare, horizontally laminated sandstone Common grain types are monocrystalline (Sh), and massive sandstone (Sm); and and polycrystalline quartz, feldspars, At the northern tip of the Fra Cristobal (4) chert beds that are likely silicified volcanic rock fragments, and volca- Range (just into Socorro County) is a small volcanic ash layers. Sandstone beds at nic chert grains (Fig. A5.6A–E). Less area (less than 2 km2) of flat-lying to gen- the type locality locally display soft-sedi- common are granitic rock fragments (Fig. tly dipping sedimentary rocks consisting ment deformation structures and contain A5.6D). Schistose metamorphic rock frag- largely of sandstone (Fig. 2). These strata fossil wood. ments and mica (biotite) are rare. Feldspars are juxtaposed with Precambrian granitic At the McRae Forest section (Fig. include untwinned grains (mostly ortho- rocks to the south along a high-angle, A3.13), the exposed thickness of the clase), plagioclase, microcline, and micro- east-striking fault (Fig. 15). Immediately Double Canyon Formation is 272 m, and perthite. Some of the feldspars appear south of the fault in this area, sandstone the contact with the underlying Flying fresh but most are altered. Volcanic rock and boulder conglomerate lie on the Eagle Canyon Formation is a fault. The fragments exhibit feldspar (plagioclase) granite with a horizontal, depositional succession is composed of abundant mud- phenocrysts and other, smaller volcanic contact (Fig. 11F). stone and covered units, sandstone, subor- grains (Fig. A5.6E). Rarely, volcanic chert Cserna (1956) mapped these rocks dinate conglomerate and one limestone bed displaying spherulitic? texture is present. as Mesaverde Formation, but did not (calcrete) near the middle of the exposed The sandstone contains small amounts explain his choice. Using lithologic cri- section. Mudstone and covered units are of matrix. teria, McCleary (1960), and Kelley and up to 18.1 m thick. Mudstone is mostly Due to the high content of feldspars, McCleary (1960) favored the younger greenish, but also displays red and rarely most sandstones of the Double Canyon McRae, either the José Creek Formation yellowish hues. Formation plot into the field of arkose; or José Creek–Hall Lake transition zone. In the McRae Forest section conglom- subordinately, sandstones plot into the Hunter (1986) called the rocks “North erate and sandstone units are mostly less field of subarkose, sublitharenite, and Fra Cristobal beds,” and considered them than 3 m thick. Conglomerates are trough lithic arenite (classification scheme of to belong to an undetermined part of the cross-bedded (Gt), massive (Gm), rarely Pettijohn et al., 1987). The average McRae Formation. matrix supported (Gmm), and are up to composition is Q55F19L26 (arkose). In the The sedimentary rocks at the northern 3 m thick. The unit 13 conglomerate at the classification scheme of McBride (1963), tip of the Fra Cristobal Mountains are (faulted) base of the Double Canyon For- most sandstones are feldspathic litharenite, mainly sandstone but include interbeds of mation is composed of quartzite, granite subordinately lithic subarkose, and rarely conglomerate (Fig. 11E–F) and sandstone and volcanic clasts with diameters up lithic arkose. with chert clasts and grains that may rep- to 10 cm. The conglomerate of unit 15 resent silicified volcanic ash (Fig. A3.14). contains clasts of granite and quartzite up Depositional environments The predominant sandstones are light gray to 20 cm in diameter. The most common or yellowish to brownish gray, fine to very sandstone lithotype is trough cross-bed- The lithofacies association of the Dou- coarse grained, and composed of roughly ded sandstone (St), which is present as ble Canyon Formation indicates that it 60 to 90% quartz, 10 to 30% lithic grains single-storey beds up to 0.8 m thick and represents fluvial deposits of floodplains that are mostly chert, and a few percent multistorey units up to 3.7 m thick. Hori- and major channels of a braided to to 20% feldspar. Sparkly overgrowths are zontally laminated sandstone (Sh) intervals anastomosing fluvial system (Miall, 1996, present on quartz grains. The sandstone is are up to 9.5 m thick. Massive sandstone 2010). The channel deposits are generally laminated to thickly bedded, and exhib- (Sm) is also common, mostly as thin beds coarser-grained than in the underlying its planar cross-lamination together (<1 m) and rarely as thicker units up to formations of the McRae Group. with larger-scale planar and trough 2.6 m thick. cross-bedding. Many beds contain

Spring 2019, Volume 41, Number 1 31 New Mexico Geology rounded pebbles of quartz and white, “Petrified wood is present, including palm pretations by Kelley and McCleary (1960). gray, and black chert that range up to wood.” Hunter (1986, p. 60) mentioned In contrast, Nelson (1986) interpreted this about 8 cm in diameter (Fig. 11E). The “leaf and wood impressions.” If the wood outcrop as McRae overlying Precambrian rock is well indurated and erodes to fairly is palm (e.g., Palmoxylon), its age could be above a detachment fault, but, like Kelley continuous ledges. Talus-covered slopes Cretaceous (and no older) or Paleogene. and McCleary (1960), we see the contact between ledges may be underlain by The stratigraphic identity of the strata as depositional. Granitic cobbles and peb- less-resistant lithologies such as mudstone, at the northern end of the Fra Cristobal bles in the upper Hall Lake and Double but no exposures were found. Lack of Mountains cannot be positively deter- Canyon formations near the southern mudstone exposures handicaps inter- mined. The Cambrian Bliss Formation and end of the range likely were derived from pretation, because mudstone color and the Pennsylvanian Red House Formation, this uplift. character would help to distinguish candi- which rest directly on Precambrian base- date formations. ment elsewhere in the range, can be ruled Discussion The silica-rich sandstone beds at out based on their very different lithologic the northern tip of the Fra Cristobal composition (most of their sandstones are Petrofacies Mountains are white to light greenish quartz arenites). Initially we considered the gray, vitreous to semi-vitreous, and break Ash Canyon Formation, based on quartz- Based on thin-section point counts, we can with conchoidal fracture. Beds are about rich sandstone containing rounded quartz identify five petrofacies in the Cretaceous 20 to 150 cm thick, and small pieces of and chert pebbles. We now disfavor the Ash strata of central Sierra County, two in chert are present as angular rip-up clasts Canyon because the pebbles are too large, marine sandstones and three in fluvial within sandstone. Chert-like rocks in the the sandstone contains too much feld- sandstones (Fig. 16). In the lower, domi- José Creek and Double Canyon Forma- spar, and the Ash Canyon lacks so many nantly marine deposits of the Cretaceous tions in the southern part of the range have chert clasts or grains. Moreover, as W.H. section in Sierra County, sandstones of been interpreted as silicified volcanic ash. Seager (written communication to W. J. the Dakota Formation are characterized Specifically, the lower part of the Double Nelson, 2017) pointed out, finding the Ash by high textural and compositional matu- Canyon Formation contains greenish, Canyon in direct contact with Precambrian rity. Dakota sandstones are composed chert-like rock. basement is contrary to regional trends. The almost entirely of quartz-monocrystalline, South of the fault, conglomerate deposits in question are unlike the volcanic polycrystalline, and microcrystalline or composed of granitic cobbles up to 30 litharenite that characterizes the José Creek cryptocrystalline quartz (the latter types cm across in a sandstone matrix lies with and Hall Lake formations, and likewise, are referred to as “chert” here), and are a channel-form contact on Precambrian bears little resemblance to the Love Ranch therefore classified as quartz arenite. granitic rock (Fig. 11F). The conglomerate or any younger Cenozoic deposits. All other sandstones in the marine fines upward into sandstone composition- Partially by elimination, our preferred interval (lower interval of Mancos ally and texturally similar to that found assignment is to the Double Canyon For- Formation, Atarque Member, D-Cross north of the fault. Angular clasts of chert mation. Arkose and subarkose sandstone, Member, Gallup Formation) are very like those observed north of the fault, are conglomerate with granite pebbles and similar in composition to one another, and present in the sandstone and imply that cobbles, and layers of siliceous rock, some are somewhat less mature than those of sedimentary rocks on both sides of the of which are green, characterize this unit the Dakota Formation. The most common fault are more or less the same formation to the south. The age of the Double Can- grain type is quartz, but moderate amounts and age. The narrow fault zone and lack of yon has not been precisely determined, it of detrital feldspars and rock fragments strong deformation suggest that displace- is younger than the Hall Lake Member, are also present. Most of these sandstones ment was modest, just enough to place which contains late Maastrichtian (latest are classified as subarkose, and some are Precambrian rocks below the valley floor Cretaceous) dinosaurs, and older than sublitharenites (classification of Pettijohn on the north (Fig. 15). Large-displacement the Eocene Love Ranch Formation. Most et al., 1987). faults that strike east-west are uncommon likely, the Double Canyon is largely, if not Within the fluvial facies (Flying elsewhere in the range. entirely, Paleocene age strata. Eagle Canyon Formation through McRae The only fossils we observed were non- On this basis, we infer that the granitic Group), three petrofacies can be distin- descript, twig-like impressions and casts core of the Fra Cristobal range was uplifted guished: of woody plant material in sandstone and and eroded during latest Cretaceous to 1. Petrofacies A of higher compo- in chert. McCleary (1960, p. 22) reported Paleocene time, consistent with earlier inter- sitional maturity, characterized by a high percentage of quartz (monocrystalline, polycrystalline and chert) and compara- South No vertical exaggeration North tively low amounts of detrital feldspars and lithic fragments (Q>70, F<18, L<25). This petrofacies includes sandstone of the Flying NFC Conglomerate Eagle Canyon, Ash Canyon and, locally, section Kdc? Fra Cristobal North the basal José Creek formations. Within 1500 m section this petrofacies, Flying Eagle Canyon sand- Precambrian stones (dominantly sublitharenite) are least mature, and Ash Canyon sandstones 1000 m (quartz arenite and sublitharenite) are FIGURE 15. Cross section through Cretaceous outcrops at the northern end of the Fra Cristobal more mature. Mountains. Kdc = Double Canyon Formation.

Spring 2019, Volume 41, Number 1 32 New Mexico Geology 2. Petrofacies B of lower composi- Hall Lake sandstones are less variable in quartz (chert) is included in the lithic tional maturity, including sandstones of composition, consisting mostly of lithic fraction. Lithic fragments in the Hall the basal José Creek, Hall Lake and Dou- arenites and subordinate arkoses. Lake and Double Canyon formations are ble Canyon formations. The Hall Lake 3. Petrofacies C. Sandstones of dominantly derived from intermediate and Double Canyon formations contain the José Creek Formation are almost and silicic volcanic rocks. Detrital feld- relatively high amounts of lithic fragments exclusively composed of volcanic rock spars (plagioclase) in these formations are and detrital feldspar grains, but the pro- fragments and detrital plagioclase. These also mostly derived from volcanic rocks, portion of lithic fragments is notably less lithic arenites have a unique composition and a small part (particularly microcline than that of Petrofacies C (José Creek Fm). compared to other post-Gallup lithostrati- and perthite) from granitic source rocks. Double Canyon sandstones have higher graphic units. Carbonate clasts derived from the rework- quartz content, and Hall Lake sandstones Thus, José Creek, Hall Lake, and ing of pedogenic calcrete also form a have slightly larger amounts of feldspar Double Canyon sandstones are charac- substantial component of individual sand- and lithic fragments. Overall, Double terized by significantly higher amounts stone and conglomerate beds in McCrae Canyon sandstones display a wider range of lithic fragments and detrital feldspars Group deposits. Other sedimentary rock in composition, from lithic arenite to than Flying Eagle and Ash Canyon fragments (such as reworked siltstone sublitharenite, subarkose, and arkose. sandstones—even when microcrystalline fragments) are rare. Similar results were noted by Wallin (1983) and Hunter (1986), who considered chert grains as lithic fragments rather Q than quartz. Hunter (1986) reported a Quartz arenite very high quartz content for sandstones of Sublitharenite the Ash Canyon Formation and indicated Subarkose Dakota Formation that sandstones of the José Creek and Hall ++ Rio Salado Member Atarque Member Lake formations are almost exclusively + Fite Ranch Member composed of lithic fragments and pla- D-Cross Member gioclase feldspars. Gallup Formation Basal José Creek sandstones, according to our results, are characterized by high quartz content and belong to petrofacies A, whereas the bulk of the José Creek sandstones belong to petrofacies C. Hall Lake and Double Canyon sandstones belong to petrofacies B. Hall Arkosic arenite Lithic arenite Lake and Double Canyon sandstones and most of the José Creek sandstones are “feldspathic sandstones” (containing more than 5% detrital feldspar). They F L may also be termed “volcanic arkoses” or “plagioclase arkoses” (sensu Folk, 1974), due to the high amount of detrital pla- Q Ash Canyon Fm. gioclase derived from volcanic rocks and + + + + + the presence of abundant intermediate to ++ +++ + silicic volcanic lithic fragments. Such sed- ++ + basal Josè Creek Fm. + + + ++ + + + iments indicate nearby volcanic activity. + + + ++ + Deposition must have been relatively rapid Double Canyon Fm. + + + Flying Eagle Canyon Fm. + because of the susceptibility of feldspar to weathering. Abundance of fresh feldspar and granitic rock fragments in the upper Hall Lake Fm. McRae Group also suggests provenance from nearby Precambrian granitic rocks. We propose that the northern part of the Fra Josè Creek Fm. (Hunter, 1986) Cristobal Range was undergoing uplift related to Laramide tectonic activity during deposition of the sediments there.

Timing of Laramide deformation

F L Previous reconstructions of Laramide tectonism in southern New Mexico (Sea- FIGURE 16. Ternary diagrams illustrating petrofacies of Cretaceous sandstones in central Sierra ger, 1983; Seager and Mack, 1986, 2003; County, using the classification scheme of Pettijohn et al. (1987). Seager et al., 1997) primarily address the

Spring 2019, Volume 41, Number 1 33 New Mexico Geology region south of the Fra Cristobal Range. Geologic history Formation. The T1 transgression culmi- This investigation provides some insights nated with relatively low clastic input into Laramide uplift within and close to A comprehensive understanding of the during deposition of the Greenhorn the Fra Cristobals and points to areas in Cretaceous strata in Sierra County allows Member of the Mancos. The succeeding which further research is required. a more detailed interpretation of their Turonian R1 regression began with marine As discussed by Seager and Mack relationship to Cretaceous strata to the deposition of the Carlile Member of the (2003), the Cretaceous succession from north and to geologic events of Cretaceous Mancos Formation followed by shoreline the Dakota Formation through the Ash time in New Mexico. We summarize these and coastal plain deposits of the Atarque Canyon Formation represents deposition events in the context of broad transgres- and Campana members (respectively) of in the Laramide foreland basin. The upper sive-regressive cycles of deposition in the the Tres Hermanos Formation. part of the Ash Canyon Formation con- Western Interior Seaway (Weimer, 1960; The onset of the late Turonian T2 tains the first evidence for regional uplift, Molenaar, 1983) and in terms of the Lar- transgression is marked by shoreline in the form of sedimentary chert clasts amide orogenic history discussed above deposits of the Fite Ranch Member of the that are not found in older units. These (Fig. 17). Tres Hermanos Formation. Where the R1– cherty gravels and associated quartzose Cretaceous deposition in Sierra County T2 turnaround is in the underlying Cam- sands probably were derived from Paleo- was initiated during the T1 transgression pana Member is not clear. Open-marine zoic rocks undergoing erosion on those of the Western Interior Seaway during deposition of the lower D-Cross Member uplifts. In particular, limestone of the middle-late Cenomanian time. Deposition of the Mancos Formation records the Pennsylvanian Gray Mesa Formation may began with fluvial and then paralic-near culmination of the T2 transgression. have provided an abundant local source shore deposits of the Dakota Formation, The upper sandy part of the D-Cross of chert. Closer analysis of chert pebbles followed by open-marine deposition of Member represents the onset of the in the Ash Canyon, particularly a search the Graneros Member of the Mancos R2 regression of late Turonian-early for included fossils, might strengthen sup- position regarding possible source rocks. The José Creek Formation records the onset of significant volcanism close to LITHOSTRATIGRAPHIC UNIT geologic Ma STAGE events the study area. Seager and Mack (2003, p. 66 Double Canyon Formation 48) referred to “an apparently collapsed Hall Lake Formation stratovolcano located east-northeast of Laramide Hillsboro” in western Sierra County as Maastrichtian orogeny a likely source. Ranging from fine ash to 70 boulder-sized clasts, volcanic material Josè Creek Formation overwhelmed other types of sediment in McRae Group the José Creek (also see Hunter, 1986). volcaniclastics The Hall Lake and Double Canyon appear formations reflect somewhat reduced depo- 75 sition of volcaniclastic sediment combined Ash Canyon with increasing erosion of nearby basement Formation R4, Laramide uplifts. Extensive areas of Precambrian Campanian orogeny begins basement were exposed, supplying arkosic 80 sand and granitic pebbles and cobbles to the Cutter sag area. The Rio Grande uplift to the southwest was a major contributor (Seager Flying Eagle and Mack, 1986) and likely was accompa- T4? Canyon 85 nied by uplift of what is now the northern Fra Santonian Formation Cristobal Range. The apparent deposition R3? of Double Canyon strata directly on Pre- T3? cambrian basement at the northern end of Coniacian the range provides the strongest evidence 90 for uplift inthat area. Gallup Formation R2 D-Cross Member To refine these conclusions, more Turonian T2 accurate dating of the upper Hall Lake Tres Hermanos Formation Carlile Member R1 and Double Canyon units (and the Love Greenhorn Member Ranch Formation) is required. Dinosaur 95 Mancos fossils establish the age of the lower Hall Formation Graneros Member T1 Lake, but younger strata have yielded Cenomanian Dakota Formation only fossil wood and other plant remains of poorly constrained age. Radioisotopic dating of apparent volcanic ash layers 100 in the Double Canyon Formation could potentially be fruitful. FIGURE 17. Summary of age assignments and geological events recorded by the Cretaceous strata in Sierra County.

Spring 2019, Volume 41, Number 1 34 New Mexico Geology Coniacian time. The Gallup Formation Campanian event and that the base of the Emerging Opportunities: Paleontological Soci- ety Papers, v. 11, p. 23–43. represents shoreline deposits of that José Creek Formation is ~75 Ma (Fig. 17). Buck, B.J., 1992, Deterioration of paleoclimate The age of the lower part of the Hall regression, overlain by coastal plain depos- in the Late Cretaceous, indicated by paleosols its of the lower part of the Flying Eagle Lake Formation is constrained by dino- in the McRae Formation, south-central New Canyon Formation. saur biostratigraphy as late Maastrichtian Mexico [M.S. thesis]: Las Cruces, New Mex- Above this clear record of the T1–R1 (~66–68 Ma). Although treated here as ico State University, 69 p. and T2–R2 cycles, there is no obvious units of Cretaceous age, the upper Hall Buck, B.J., and Mack, G.H., 1995, Late Cre- record in Sierra County of the late Conia- Lake Formation and the Double Canyon taceous (Maastrichtian) aridity indicated by cian T3 transgression, early Santonian R3 Formation may be of Paleocene age. The paleosols in the McRae Formation, south-cen- regression, and the middle-late Santonian overlying Love Ranch Formation of likely tral New Mexico: Cretaceous Research, v. 16, T4 transgression. This reflects the fact Eocene age represents the final pulse of the p. 559–572. Buck, B.J., Mack, H.H., and Upchurch, G.R., Jr., that Sierra County was at least 100 km Laramide orogeny in Sierra County. 1992, Paleosols and paleoflora of the Upper landward (south) of the T3 and T4 shore- Cretaceous (Maastrichtian) McRae Forma- lines, which were located north of Socorro Acknowledgments tion, south-central New Mexico, and their (Molenaar, 1983, figs. 9–10). Brackish implications to paleoclimate: New Mexico water bivalves (oysters) in beds in the We are particularly grateful to Ted Turner Geology, v. 14, p. 77. upper part of the Flying Eagle Canyon for permission to work on the Armendaris Bushnell, H.P., 1953, Geology of the McRae Formation may record one of these trans- Ranch, and to former ranch manager Tom Canyon area, Sierra County, New Mexico [M. gressions, but no age data are available by Waddell, who assisted our access to the S. thesis]: Albuquerque, University of New Mexico, 106 p. which to make a precise correlation. If we ranch and our fieldwork there in many consider the Flying Eagle Canyon Forma- Bushnell, H.P., 1955a, Mesozoic stratigraphy of ways. We are also grateful to the U. S. south-central New Mexico, in Fitzsimmons, tion to encompass the time from the last Bureau of Land Management for per- J.P., ed., South-Central New Mexico: New phase of R2 through T4, then it is essen- mitting our paleontological fieldwork on Mexico Geological Society, Guidebook 6, p. tially equivalent to the entire Coniacian Federal lands in and around the Caballo 81–87. and Santonian stages, or about 6 million Mountains. M. Brett-Surman and R. J. Bushnell, H.P., 1955b, Stratigraphy of the years (Fig. 17). Emry made access to the Smithsonian fossil McRae Formation, Sierra County, New Mex- The R4 regression is of early Cam- collection possible. P. Sealey provided help ico: The Compass of Sigma Gamma Epsilon, panian age and also marks the onset of with invertebrate fossil identifications. In v. 33, p. 9–17. the Laramide orogeny (e. g., Kauffman the field, we received diverse assistance Cikoski, C.T., Nelson, W.J., Koning, D.J., Elrick, S., and Lucas, S.G., 2017, Geologic map of and Caldwell, 1993). We hypothesize that from A. Cantrell, S. Dalman, A. Erickson, deposition of the upper part of the Ash the Black Bluffs 7.5-minute quadrangle, Sierra D. Koning, A. Lichtig, J. Sayler and T. County, New Mexico: New Mexico Bureau Canyon Formation most likely reflects Suazo, for which we are grateful. We also of Geology and Mineral Resources, Open-File that tectonic event, so it represents an thank C. Cikoski, D. Koning and W. Seager Geologic Map OF-GM 262, scale 1:24,000. inland river system homotaxial to the for their insights on several aspects of the Coates, A.G., and Kauffman, E.G., 1973, early Campanian Menefee Formation data and interpretations presented here. Stratigraphy, paleontology and paleoenviron- of northern New Mexico, which is the Careful reviews by B. Black, D. Koning and menmt of a Cretaceous coral thicket, Lamy, coastal plain deposit of the R4 regression. NM Geology editor B. Allen improved the New Mexico: Journal of Paleontology, v. 47, Biostratigraphic or other age data are content and clarity of the manuscript. p. 953–968. needed to test this hypothesis. Cobban, W.A., and Reeside, J.B., Jr., 1952, Cor- The base of the McRae Group relation of the Cretaceous formations of the records the first significant influx of -vol United States: Geological Society of America References Bulletin, v. 63, p. 1011–1044. canic detritus into the Cretaceous section Cobban, W.A., Hook, S.C., and Kennedy, W.J., of Sierra County. A likely source of this Amato, J.M., Mack, G.H., Jonell, T.N., Seager, 1989, Upper Cretaceous rocks and ammo- detritus was the Copper Flat complex, a W.R., and Upchurch, G.R., 2017, Onset of the nite faunas of southwestern New Mexico: Late Cretaceous magmatic center located Laramide orogeny and associated magmatism New Mexico Bureau of Mines and Mineral near Hillsboro in southwestern Sierra in southern New Mexico based on U-Pb Resources, Memoir 45, 137 p. County (Seager et al., 1997; McMil- geochronology: Geological Society of America Cobban, W.A., Hook, S.C., and McKinney, K.C., lan, 2004), although other evidence of Bulletin, v. 129, p. 1209–1226. 2008, Upper Cretaceous molluscan record similar-aged volcanic centers could be Barker, I.R., Moser, D.E., Kamo, S.L., and Plint, along a transect from Virden, New Mexico to buried by younger rift basin fill between A.G., 2011, High-precision U-Pb zircon Del Rio, Texas: New Mexico Geology, v. 30, Copper Flat and Truth or Consequences. ID-TIMS dating of two regionally extensive p. 75–92. bentonites: Cenomanian Stage, western Can- Collier, A.J., 1919, Coal south of Mancos, Mon- Radioisotopic ages of the igneous rocks ada foreland basin: Canadian Journal of Earth tezuma County, Colorado: U. S. Geological of the Copper Flats complex are late Sciences, v. 48, p. 543–556. Survey, Bulletin 691, 296 p. Campanian, ~74–75 Ma, to (for younger Bauer, R.D., 1989, Nearshore depositional envi- Collins, D.S., 1999, Laramide and post-Lara- intrusions) early Maastrichtian (~70 Ma) ronments, sediment dispersal, and provenance mide stratigraphy and tectonism on the south- (McLemore et al., 1999; McMillan, 2004). of the Dakota Sandstone, Caballo Mountains, east flank of the Fra Cristobal Mountains, Radioisotopic ages indicate that the Josè south-central New Mexico [M.S. thesis]: Las New Mexico [M.S. thesis]: Golden, Colorado Creek Formation may have been depos- Cruces, New Mexico State University, 64 p. School of Mines, 116 p. ited quickly between 76–74 Ma (Amato Bowring, S.A., Schoene, B., Crowley, J.L., et al., 2017). This suggests that the onset Ramezani, J., and Condon, D.J., 2006, of McRae Group deposition was a late High-precision U-Pb zircon geochronology and the stratigraphic record: progress and promise, in Olszewski, T., ed., Geochronology:

Spring 2019, Volume 41, Number 1 35 New Mexico Geology Cope, E.D., 1871, [Verbal communication on Ewing, T.E., 2012, Geology and hydrocarbon Hook, S.C., 1983, Stratigraphy, paleontology, pythonomorphs]: Proceedings of the Ameri- resource potential of Cretaceous strata in the depositional framework, and nomenclature can Philosophical Society, v. 11, p. 571–572. Jornada del Muerto, Sierra and Socorro coun- of marine Upper Cretaceous rocks, in Chapin, Cope, E.D., 1875, The Vertebrata of the Creta- ties, New Mexico, in Lucas, S.G. McLemore, C.E., and Callender, J.F., eds., Socorro Region ceous formations of the West: U. S. Geological V.T., Lueth, V.W., Spielmann, J.A., and Krainer, II: New Mexico Geological Society, Guide- Survey of the Territories Report 2, 303 p. K., eds., Geology of the Warm Springs Region: book 34, p. 165–172. 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Spring 2019, Volume 41, Number 1 36 New Mexico Geology Kennedy, W.J., Cobban, W.A., and Landman, Lozinsky, R.P., Hunt, A., Wolberg, D.L., and Lucas, S.G., Dalman, S.G., Lichtig, A.J., Elrick, N.H., 2001, A revision of the Turonian mem- Lucas, S.G., 1984, Late Cretaceous dinosaur S., Nelson, W.J., and Krainer, K., 2017a, Stra- bers of the ammonite subfamily Collignonicer- discoveries from the McRae Formation, tigraphy and age of the dinosaur-dominated atinae from the United States Western Interior Sierra County, New Mexico: New Mexico fossil assemblage of the Upper Cretaceous and Gulf Coast: Bulletin of the American Geology, v. 6, p. 72–77. Hall Lake Member of the McRae Formation, Museum of Natural History, v. 267, 148 p. 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Spring 2019, Volume 41, Number 1 37 New Mexico Geology McMillan, N.J., 2004, Magmatic record of Lara- NMBGMR, 2003, Geologic map of New Pike, W.S., Jr., 1947, Intertonguing marine and mide subduction and the transition to Tertiary Mexico: New Mexico Bureau of Geology and nonmarine Cretaceous deposits of New Mex- extension: Upper Cretaceous through Eocene Mineral Resources, 2 sheets, scale 1:500,000. ico, Arizona, and southwestern Colorado: igneous rocks of New Mexico, in Mack, G.H., Obradovich, J.D., 1993, A Cretaceous time Geological Society of America, Memoir 24, and Giles, K.A., eds., The geology of New scale; in Caldwell, W.G.E., and Kauffman, 103 p. Mexico: a geologic history: New Mexico E.G., eds., Evolution of the Western Interior Rankin, C.H., 1944, Stratigraphy of the Colo- Geological Society, Special Publication 11, p. basin: Geological Association of Canada, rado Group, Upper Cretaceous, in northern 249–270. Special Paper 39, p. 1–30. 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Spring 2019, Volume 41, Number 1 38 New Mexico Geology Seager, W.R., and Mack, G.H., 2003, Geology Tidwell, W.D., Ash, S.R., and Parker, L.R., 1981, of the Caballo Mountains, New Mexico: Cretaceous and Tertiary floras of the San Juan New Mexico Bureau of Geology and Mineral Basin, in Lucas, S.G., Rigby, J.K., Jr., and Kues, Resources, Memoir 49, 135 p. B.S., eds., Advances in San Juan Basin pale- Seager, W.R., and Mack, G.H., 2005, Geologic ontology: Albuquerque, University of New map of Apache Gap and Caballo quadrangles, Mexico Press, p. 307–332. Sierra County, New Mexico: New Mexico Tucker, M.E., 1988, Techniques in Sedimentol- Bureau of Geology and Mineral Resources, ogy: Oxford, Blackwell Scientific Publications, Geologic Map 74, 2 sheets, map scale 394 p. 1:24,000. Upchurch, G.R., Jr., and Mack, G.H., 1998, Seager, W.R., Mack, G.H., and Lawton, T.F., Late Cretaceous leaf megafloras from the José 1997, Structural kinematics and depositional Creek Member, McRae Formation of New history of a Laramide uplift-basin pair in Mexico, in Mack, G.H., Austin, G.S., and southern New Mexico: implications for Barker, J.M., eds., Las Cruces Country II: New development of intraforeland basins: Geo- Mexico Geological Society, Guidebook 49, p. logical Society of America Bulletin, v. 109, p. 209–222. 1389–1401. Wallin, E.T., 1983, Stratigraphy and paleo- Sears, J.D., 1925, Geology and coal resources environments of the Engle coal field, Sierra of the Gallup-Zuni basin, New Mexico: U.S. County, New Mexico [M.S. thesis]: Socorro, Geological Survey, Bulletin 767, 53 p. New Mexico Institute of Mining and Technol- Shaver, R.H., Ault, C.H., Burger, A.M., Carr, ogy, 127 p. D.D., Droste, J.B., Eggert, D.L., Gray, H.H., Warren, R.G., 1978, Characterization of the Harper, Denver, Hasenmueller, N.R., Hasen- lower crust-upper mantle of the Engle basin, mueller, W.A., Horowitz, A.S., Hutchison, Rio Grande rift, from a petrochemical and H.C., Keith, B.D., Keller, S.J., Patton, J.B., field geologic study of basalts and their inclu- Rexroad, C.B., and Wier, C.E., 1986, Com- sions [M. S. thesis]: Albuquerque, University pendium of Paleozoic rock-unit stratigraphy of New Mexico, 156 p. in Indiana–a revision: Indiana Geological Weimer, R.J., 1960, Upper Cretaceous stra- Survey, Bulletin 59, 203 p. tigraphy, Rocky Mountain area: American Shumard, G.G., 1860, The geological structure Association of Petroleum Geologists Bulletin, of the “Jornada del Muerto,” New Mexico: v. 44, p. 1–20. St. Louis Academy of Science Transactions, v. White, C.A., 1878, Report on the geology of 1, p. 341–355. a portion of northwestern Colorado: U. S. Suazo, T.L., Cantrell, A.K., and Lucas, S.G., Geological and Geographical Survey of the 2014, Newly discovered dinosaur fossils from Territories, 10th Annual Report, p. 3–59. the Upper Cretaceous (late Maastrichtian) Wilmarth, M.G., 1928, Lexicon of geologic McRae Formation, Sierra County, New Mex- names of the United States: U. S. Geological ico: New Mexico Geological Society, 2014 Survey, Bulletin 896, 2396 p. Annual Spring Meeting, Proceedings Volume, Wolberg, D.L, Lozinsky, R.P., and Hunt, A.P., p. 60, http://nmgs.nmt.edu/meeting/2014/ 1986, Late Cretaceous (Maastrichtian–Lan- Spring_Meeting_Program_2014.pdf cian) vertebrate paleontology of the McRae Sullivan, R.M., and Lucas, S.G., 2015, Cre- Formation, Elephant Butte area, Sierra taceous vertebrates of New Mexico, in County, New Mexico, in Clemons, R.E., King, Lucas, S.G., and Sullivan, R.M., eds., Fossil W.E., Mack, G.H., and Zidek, J., eds., Truth or vertebrates in New Mexico: New Mexico Consequences Region: New Mexico Geologi- Museum of Natural History and Science, cal Society, Guidebook 37, p. 227–234. Bulletin 68, p. 105–129. Sullivan, R.M., Boere, A.C., and Lucas, S.G., Appendices for this paper are available at: 2005, Redescription of the ceratopsid dinosaur https://geoinfo.nmt.edu/repository/index.cfml? Torosaurus utahensis (Gilmore, 1946) and a rid=20190002 revision of the genus: Journal of Paleontology, v. 79, p. 564–582. Thompson, S. III, 1955a, Geology of the southern part of the Fra Cristobal Range, Sierra County, New Mexico [M.S. thesis]: Albuquer- que, University of New Mexico, 75 p. Thompson, S. III, 1955b, Geology of the Fra Cristobal Range, in Fitzsimmons, J.P., ed., South-Central New Mexico: New Mexico Geological Society, Guidebook 6, p. 155–157. Thompson, S. III, 1961, Geology of the southern part of the Fra Cristobal Range, Sierra County, New Mexico: New Mexico Bureau of Mines and Mineral Resources, Open-file Report 380, 89 p. and map, scale 1:24,000.

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