Lucas, S.G., DiMichele, W.A. and Krainer, K., eds., 2017, Carboniferous-Permian transition in Socorro County, New Mexico. New Mexico Museum of Natural History and Science Bulletin 77. 1 CARBONIFEROUS-PERMIAN TRANSITION IN SOCORRO COUNTY, NEW MEXICO, USA: AN OVERVIEW

SPENCER G. LUCAS1, KARL KRAINER2, BRUCE D. ALLEN3 and WILLIAM A. DIMICHELE4

1New Mexico Museum of Natural History, 1801 Mountain Road NW, Albuquerque, New Mexico M 87104; email: [email protected]; 2Institute of Geology, University of Innsbruck, Innrain 52, A-6020 Innsbruck, Austria ; 3New Mexico Bureau of Geology & Mineral Resources, 801 Leroy Place, Socorro, New Mexico 87801; 4Department of Paleobiology, NMNH Smithsonian Institution, Washington, DC 20560

Abstract— This volume documents the results of 20+ years of field, laboratory and museum research on the Pennsylvanian-Permian rocks and fossils of Socorro County, New Mexico. The articles in this volume report studies of the Pennsylvanian-Permian strata east of Socorro (Joyita Hills-Cerros de Amado-Carthage area), in the Los Pinos Mountains (Sepultura Canyon area), in the Little San Pascual Mountains and at Bell Hill in the Southern San Mateo Mountains. Lithostratigraphy, sedimentary petrography, microfacies analysis and sedimentological interpretation as well as diverse paleontological studies (fossil plants, calcareous microfossils, conodonts, fossil insects, tetrapod footprints, coprolites and fossil fishes) are presented. The entire Pennsylvanian-Permian stratigraphic section in Socorro County is about 2 km thick. The Pennsylvanian strata are a complex succession of sedimentary rocks of marine and nonmarine origin deposited during the Middle-Late Pennsylvanian. These are synorogenic deposits of the ancestral Rocky Mountain (ARM) orogeny and associated marine carbonates of shallow seaways along the western periphery of equatorial Pangea. They are overlain by another complex succession of clastic and carbonate strata of Permian age, the oldest of which were deposited during the final phase of the ARM orogeny. Fossils (primarily the fusulinids and conodonts) provide the age control for the Pennsylvanian-Permian strata of Socorro County. They also are a significant part of the data used to interpret local and regional paleoenvironments and depositional systems. In addition, many of the fossils play a broader role in the understanding of late Paleozoic biotic and evolutionary events.

INTRODUCTION this volume, some data remain to be analyzed and written up, and these Socorro County (Fig. 1) is located in central New Mexico and will be published elsewhere. The present article is intended to be an encompasses an area of 6,649 square miles (17, 221 square kilometers). introduction to and overview of the contents of this volume. Most of the county is part of the Basin and Range physiographic SOME HISTORY province. Thus, the older sedimentary bedrock, of late Paleozoic age, is exposed in the rugged mountain ranges and other uplifts of Socorro Late Paleozoic strata and fossils have a long history of study in County (Fig. 1). The oldest bedrock, which forms the cores of most Socorro County, extending back to the early works of Herrick (1900, of the mountain ranges, is Proterozoic basement, mostly metamorphic 1904), Lee (1909) and Darton (1922, 1928), among others. Nevertheless, rocks and granite. Sedimentary rocks that rest on the basement are despite a long history of study, until recently relatively little was known Pennsylvanian across Socorro County, except in the Sierra Ladrones of their paleontology, and their stratigraphy also was in need of more and Magdalena Mountains, where a thin interval of Mississippian detailed study. A turning point in the study of these late Paleozoic rocks strata underlies the Pennsylvanian strata. The Pennsylvanian strata are and fossils took place only a little over 20 years ago, in 1996. a complex succession of sedimentary rocks of marine and nonmarine In that year, Ed Frye and Mike O’Keefe, two engineering students origin deposited during the Middle-Late Pennsylvanian. These are at New Mexico Tech, showed one of us (SGL) some Pennsylvanian- synorogenic deposits of the ancestral Rocky Mountain (ARM) orogeny Permian fossil sites they had discovered in the Cerros de Amado, east and associated marine carbonates of shallow seaways along the western of Socorro. These were an accumulation of shark’s teeth and denticles periphery of equatorial Pangea. They are overlain by another complex in Middle Pennsylvanian strata, upright fossilized stumps and a black succession of clastic, carbonate and lesser evaporite strata of Permian shale interval with conchostracans and the bivalve Dunbarella in the Upper Pennsylvanian rocks, and an extensive tetrapod footprint age, the oldest of which were deposited during the final phase of the locality in the lower Permian red beds. The sites discovered by Frye ARM orogeny. The entire upper Paleozoic stratigraphic section in and O’Keefe were an important indication of the highly fossiliferous Socorro County is about 1.5 km thick (Fig. 2). nature of the Pennsylvanian and Permian strata in the Cerros de The Pennsylvanian and Permian strata of Socorro County contain a Amado. Clearly, the Pennsylvanian-Permian strata east of Socorro diverse and extensive fossil record. Marine strata produce microfossils contained a largely unexplored and much understudied fossil record of cyanobacteria, algae, foraminiferans (including fusulinids) and that awaited prospecting, collection and study. There had been some conodonts as well as macrofossils, mostly of the shelly benthos— published studies of Pennsylvanian and Permian plants (Herrick, 1900; brachiopods, crinoids, bryozoans and molluscs. The nonmarine strata Hunt, 1983) and of Permian bones and footprints (e. g., Berman, 1993; contain diverse paleofloras, fossils of arthropods (notably insects), trace Hunt et al., 1995) from this area, but much more, particularly in the fossils (mostly tetrapod footprints and coprolites) and tetrapod body Pennsylvanian strata, remained to be discovered. fossils. These fossils (primarily the fusulinids and conodonts) provide In 2002, a major field campaign to collect fossil plants from the age control for the Pennsylvanian-Permian strata of Socorro County. these rocks was begun by Smithsonian paleontologists led by one of They also are a significant part of the data used to interpret local and us (WAD). At that time, two of us (SGL and KK) were studying the regional paleoenvironments and depositional systems. In addition, Bursum Formation across New Mexico. This project expanded in many of the fossils play a broader role in the understanding of late Socorro County to look more closely at most of the upper Paleozoic Paleozoic biotic and evolutionary events. section in order to produce more detailed lithostratigraphic, microfacies The articles in this volume are the outgrowth of the last two and biostratigraphic data. The effort in the Socorro area was joined by decades of field research on the upper Paleozoic strata of Socorro James Barrick of Texas Tech University, who extracted conodonts County. Some of this research has already been published in scientific and used them for biostratigraphic interpretation of the ages of the journals (e.g., DiMichele et al., 2007; Falcon-Lang et al., 2011, 2016), Pennsylvanian strata in the Cerros de Amado and vicinity. The search in the 60th Guidebook of the New Mexico Geological Society (Lueth for fossil plants also uncovered animal fossils, notably conchostracans, et al., 2009) and in Bulletin 59 of the New Mexico Museum of Natural insects and fossil fishes. History and Science (Lucas et al., 2013a). Even with the publication of In part driven by the planned publication of this volume, an 2

FIGURE 1. Map of Socorro County, New Mexico, showing distribution of Pennsylvanian and Permian outcrops. Localities are: AP- Abo Pass, BC- Bruton Canyon (northern Oscura Mountains), BH- Bell Hill, CDA- Cerros de Amado, LPM- Los Pinos Mountains, LSPM- Little San Pascual Mountains, LU- southern Lucero uplift, S- town of Socorro, and SL- Sierra Ladrones. effort was also made to study other Pennsylvanian-Permian outcrops blocks (Lucas et al., 2009a). Conodont biostratigraphy provides most in Socorro County. This involved fieldwork in the northern Oscura of the published age control of this Pennsylvanian section (Lucas et al., Mountains, at Abo Pass, in the Los Pinos and Little San Pascual 2009a; Barrick et al., 2013). mountains and at Bell Hill in the southern San Mateo Mountains (Fig. In this volume, Krainer et al. (2017a) detail the microfacies 1). Further work is underway and/or planned in the Oscura Mountains and petrography of the Pennsylvanian strata exposed in the Cerros de as well as in the Sierra Ladrones and Magdalena Mountains in order to Amado area, east of Socorro. These strata, assigned to the (ascending) decipher better the stratigraphy, depositional history and biostratigraphy Sandia, Gray Mesa and Atrasado formations, encompass different kinds of all the upper Paleozoic strata in Socorro County. of limestone and intercalated siliciclastic sediments. In the Sandia Formation, most sandstones are quartzarenite. In the Garcia Member OVERVIEW of the Gray Mesa Formation and in the clastic members of the Atrasado Lithostratigraphy and Biostratigraphy Formation, mixed siliciclastic-carbonate sandstone predominates. The most common limestone microfacies are bioclastic wackestone East of Socorro and floatstone. Other microfacies such as mudstone, packstone, The area east of Socorro extends from the Joyita Hills on the north grainstone and rudstone are rare, and boundstone is very rare. The most and to Carthage on the south, with its center at and around the Cerros abundant fossils in the limestone facies of the Pennsylvanian strata are de Amado (Fig. 1). Because it does not have a single geographic name, echinoderms (mostly crinoids), bryozoans and brachiopods, and the we refer to this area as “east of Socorro.” The bulk of the research dominant grain association type is bryonoderm extended. The chloralgal reported in this volume focuses on this area, which consists of rugged grain association type is subordinate. Smaller and larger benthic hills developed in faulted and folded upper Paleozoic strata exposed foraminifers, calcareous algae (mostly phylloid algae), sponges (mostly along the eastern flank of the Rio Grande rift. Much of the bedrock spicules), corals, molluscs (bivalves and gastropods), and arthropods in the Cerros de Amado consists of Pennsylvanian sedimentary rocks, (ostracods and trilobites) are less common. Most encrusting organisms and, indeed, a complete, ~ 800 m thick Pennsylvanian section for this are cyanobacteria and Palaeonubecularia, and (subordinately) sessile part of central New Mexico can be pieced together across different fault foraminifers, algae, Tubiphytes and bryozoans. 3 of Socorro, briefly described decades ago by Hambleton (1962), is detailed by Krainer and Lucas (2017) in this volume. This phylloid algal mound complex is in the Tinajas Member of the Atrasado Formation, and the mound complex shows a distinct zonation into: (1) basal bioclastic micrite pile, (2) massive algal mound facies, (3) flank bed facies and (4) capping bed facies. Only the lateral part of the mound complex is exposed; the central part is cut out by a fault. The massive algal mound facies is composed of phylloid algal floatstone and formed below wave base in a low-energy environment where the algae grew in such profusion that they dominated the sea-bottom, forming “algal meadows,” and acted as efficient sediment producers and bafflers. The algae are not preserved in life position, so they do not form algal bafflestone. Rather, they were toppled in situ or were transported for very short distances, forming algal floatstone. Mound growth most likely was stopped when the algae were subjected to higher energy conditions, probably caused by a drop in sea-level. The ARM orogeny in New Mexico is characterized by at least three pulses, one of which was at the very outset of the Permian and is reflected by deposition of the Bursum Formation. In this volume, Nelson et al. (2017) relate facies changes in the Bursum Formation east of Socorro to syndepositional tectonism. They identify three lithofacies of the Bursum Formation in the hills east of Socorro. The limestone- mudstone lithofacies comprises alternating layers of nodular to bedded marine limestone and non-fissile variegated claystone that represents paleosols. This facies is relatively thin and reflects deposition on stable, relatively high tectonic blocks where sea-level change was the prevalent factor driving sedimentation. The second facies is the laminated lithofacies of thinly layered gray to green shale, siltstone, and fine sandstone. These rocks occur in thick packages and contain fossil land plants and small invertebrates that indicate fresh to brackish water. The laminated facies accumulated on tectonic blocks that subsided rapidly and held standing water. The third facies of conglomerate and arkosic sandstone occurs widely at the base of the Bursum and intermittently in the middle and upper part of the formation. Representing deposits of shallow, low-sinuosity streams, these beds record distinct pulses of tectonic uplift in nearby ARM highlands. In this volume, Elrick et al. (2017) analyze the depositional setting of fossil wood from the Tinajas Member east of Socorro. Harris and Lucas (2017) present a preliminary report on a large skull of an actinopterygian fish from the Tinajas Member. Lerner and Lucas (2017) document the unusual occurrence of the pseudofossil Astropolithon in the upper part of the Abo Formation. Voigt and Lucas (2017) review the tetrapod footprint record from the Abo and Arroyo de Alamillo formations across Socorro County. DiMichele et al. (2017b) document the extensive record of fossil plants from the Atrasado Formation east of Socorro, and DiMichele and Lucas (2017) report the first Annularia from the Abo Formation. Hunt and Lucas (2017) and Harris et al. (2017) describe extensive coprolite assemblages from the Pennsylvanian strata east of Socorro. These contributions are discussed further below. Lucas and Krainer (2017) review the lithostratigraphy, microfacies, depositional history and biostratigraphy of the Permian strata east of Socorro. This Permian section is up to about 900 m thick and is assigned to the (ascending order): Bursum Formation, Abo Formation (Scholle and Cañon de Espinoso members), Yeso Group (Arroyo de Alamillo Formation and overlying Los Vallos Formation FIGURE 2. Summary lithostratigraphic section of the Pennsylvanian divided into Torres, Cañas and Joyita members), Glorieta Sandstone, and Permian strata of Socorro County, New Mexico. San Andres Formation and Artesia Formation. The Bursum Formation is up to 120 m thick and consists of interbedded red-bed siliciclastics The Sandia Formation is characterized by distinct lateral and and marine limestones. The Abo Formation is up to 200 m thick and vertical variations in facies and thickness, and represents early consists of siliciclastic red beds divided into the Scholle Member (~ 40 synorogenic sediments deposited during the initial phase of the ARM m of mudstone with channelized beds of crossbedded sandstone and orogeny. The Gray Mesa Formation, particularly the Whiskey Canyon conglomerate) overlain by the Cañon de Espinoso Member (~ 160 m Member, is mostly limestone that varies little in facies and thickness of mudstone, siltstone and many thin beds of sandstone that display over a large area, indicating deposition on an extensive, deeper, open climbing ripple lamination). The lower formation of the Yeso Group, the marine shelf that extended (at least) from Cedro Peak in the Manzanita Arroyo de Alamillo Formation, consists of ~ 107 m of red-bed siltstone, Mountains of Bernalillo County south to the Caballo Mountains of sandstone (mostly ripple laminar and laminar with some gypsiferous Sierra County. The Atrasado Formation is a succession of alternating beds) and very minor dolomite. The overlying Torres Member of the siliciclastic-dominated and limestone-dominated members. Viewed Los Vallos Formation is ~ 156 m thick and is mostly gypsiferous simply (climate fluctuation is also a factor, see below), siliciclastic- siltstone, claystone, gypsum and a few prominent beds of dolomite and dominated members display strong lateral variations in thickness and gypsiferous sandstone. The overlying Cañas Member is 66 m thick, facies, which are indicative of deposition during tectonically active consisting mostly of gypsum and a few beds of gypsiferous siltstone periods, whereas the limestone-dominated members are much more and dolomite. The Joyita Member is ~ 12 m thick and consists of red- consistent in facies and thickness, which, according to Krainer et al., bed sandstone that is crossbedded, ripple laminated and, in some beds, (2017a), points to deposition during tectonically stable periods. gypsiferous. The Glorieta Sandstone is up to 85 m thick and consists A particularly well known algal mound near Ojo de Amado east of crossbedded, laminar and ripple laminated quartzose sandstone. 4 The San Andres Formation is up to 125 m of mostly limestone (lime the structural geology of the Navajo Gap area, description of the type mudstone). The Artesia Formation is up to 12 m thick and consists of sections of the Gray Mesa and Atrasado formations by Krainer and red-bed siltstone and fine sandstone and minor beds of gypsum and Lucas (2004a), and Scott and Elrick’s (2004, Elrick and Scott, 2010) dolomite. It is overlain by Middle Triassic strata of the Anton Chico cycle-stratigraphic investigations of the Gray Mesa Formation on Mesa Member of the Moenkopi Formation. Sarca (Monte de Belen) in the southern Lucero uplift. According to Lucas and Krainer, Bursum deposition took place Hammond (1987) utilized a high-resolution stratigraphic in a mixture of nonmarine fluvial and shallow marine depositional nomenclature for the Pennsylvanian System in this area in order environments in a tectonically active, mostly coastal setting. The Abo to delineate details of the structural geology. Thus, he mapped Formation preserves a series of extensive muddy floodplains traversed, Pennsylvanian rocks using the stratigraphic nomenclature created early in Abo deposition, by incised rivers that later shallowed and gave by Thompson (1942), as modified by Rejas (1965) for the area east way to extensive sheetflooding (also see Seager and Mack, 2003). Yeso of Socorro. This is the same nomenclature, with some modifications sedimentation began with dominantly eolian deposition on an arid (e.g., many of Thompson’s [1942] formations are now considered coastal plain (Arroyo de Alamillo Formation) followed by deposition of member-rank units), that is presently being used for Pennsylvanian coastal sabkhas, dunes and restricted marine embayments (Torres and strata over a large portion of central New Mexico (Fig. 2). Hammond’s Cañas members of Los Vallos Formation). Yeso sedimentation ended (1987) reported thicknesses for the Sandia, Gray Mesa and Atrasado with deposition of the Joyita Member of the Los Vallos Formation, formations in the Navajo Gap area yield a total thickness of 573 m. which formed by eolian and fluvial processes during lowered sea level. In terms of its overall stratigraphic architecture, the Pennsylvanian The Glorieta Sandstone is mostly of eolian origin, and the San Andres section in the Lucero uplift/Sierra Ladrones area is similar to other Formation represents restricted to open, shallow marine deposits. The areas in Socorro County to the east. Thus, the Sandia Formation is Artesia Formation represents a landward portion of the siliciclastic characterized by a dominance of siliciclastic deposits, the Gray Mesa by shelf that developed northwest of the reefs that fringed the Delaware a preponderance of marine carbonate, and the Atrasado Formation by a basin in southeastern New Mexico-West Texas. succession of alternating slope-forming intervals containing a relative Fusulinids from the Bursum Formation east of Socorro indicate it abundance of siliciclastics and ledge-forming intervals dominated by is early Wolfcampian (Newwellian) in age. Local paleontological data marine carbonate. Wengerd (1959, fig. 6) showed the stratigraphic coupled with regional correlations indicate that the Abo Formation is distribution of some Desmoinesian and Missourian fusulinid genera in middle Wolfcampian-early Leonardian, the Yeso Group is Leonardian, his stratigraphic section for the Monte de Belen area, but comparatively the Glorieta and San Andres formations are late Leonardian, and the little detailed biostratigraphy is available for the Pennsylvanian of Artesia Formation is Guadalupian (Roadian-Wordian) in age. northwestern Socorro County. A substantial literature regarding the overlying Bursum Formation Lucero Uplift and Sierra Ladrones (Ladron Mountains) has been produced from the Carrizo Arroyo area in the Lucero uplift, 22 Upper Paleozoic strata in the northwestern part of Socorro km north of the Socorro County line. There, the Bursum Formation is County are exposed in the southern part of the Lucero uplift and in a about 100 m thick and consists of variegated nonmarine shale, mudstone relatively narrow belt extending southward along the western flank of and siltstone, with some beds of marine shale and carbonate. At Carrizo the Sierra Ladrones (Fig. 1). Structurally, the area lies along the western Arroyo, the Bursum Formation (Red Tanks Member) contains extensive margin of the Rio Grande rift and the eastern margin of the Colorado fossil assemblages that include palynomorphs, calcareous algae, Plateau. Vertical displacements along rift-bounding faults have brought charophytes, plant megafossils, non-fusulinid foraminifers, fusulinids, Paleozoic and, in the Ladron Mountains, Proterozoic basement rocks bryozoans, brachiopods, gastropods, bivalves, nautiloids, eurypterids, to the surface. Exposures of upper Paleozoic strata in the Lucero uplift ostracods, syncarid crustaceans, conchostracans, insects and some were mapped by Kelley and Wood (1946), introducing a stratigraphic other arthropods, echinoids, crinoids, conodonts, fish ichthyoliths and nomenclature that provided the lithostratigraphic names Gray Mesa, bones of amphibians and reptiles (see articles in Lucas and Zeigler, Atrasado, and Los Vallos, which are presently used for upper Paleozoic 2004a). Deposition of the Bursum Formation at Carrizo Arroyo began formation-rank units across much of central New Mexico (Fig. 2). during the latest Pennsylvanian and continued into the early Permian Pennsylvanian strata exposed in northwestern Socorro County (e.g., Lucas et al., 2013b). include the (ascending) Sandia, Gray Mesa, and Atrasado formations. Information regarding the Bursum Formation is sparse for the The Pennsylvanian rocks rest unconformably on Proterozic basement Socorro County portion of the Lucero uplift and the Ladron Mountains. or, in the southern Sierra Ladrones, a relatively thin (up to about 27 m) Kelley and Wood (1946) depicted approximately 63 and 96 m of section of Mississippian siliciclastic and carbonate strata assigned by Bursum Formation (their Red Tanks member) in their graphic sections Armstrong (1958) to the Caloso and overlying Kelly formations. The 1 and 2. Hammond (1987) reported a partial thickness of the Bursum Pennsylvanian section is overlain by Pennsylvanian-Permian strata of Formation (incomplete due to faulting) of about 30 m in the Navajo Gap the Bursum Formation. Permian strata overlying the Bursum Formation area. Krainer and Lucas (2004b) documented a poorly exposed Bursum include (ascending) the Abo Formation, Yeso Group, Glorieta section at Coyote Draw on the western flank of the Sierra Ladrones that Sandstone and San Andres Formation. The San Andres Formation is is about 120 m thick. During a recent visit to the western side of the overlain unconformably by Triassic strata assigned to the Moenkopi Sierra Ladrones, we identified an area a few km south of Hammond’s Formation. The Permian Artesia Formation is not present above the San sections that looks promising in terms of piecing together a reasonably Andres Formation in the northwestern part of Socorro County. complete and well exposed section of the Bursum Formation, including Kelley and Wood (1946) measured several sections in the vicinity a good exposure of its upper contact with the overlying Abo Formation. of the Lucero uplift, including a section in the Navajo Gap area (their As with the Bursum Formation, information regarding younger graphic section 1) that lies within Socorro County, just northwest of the Permian stratigraphic units in northwestern Socorro County is sparse. Sierra Ladrones. The thickness of the Sandia, Gray Mesa and Atrasado A complete Permian section was described by Lucas and Zeigler formations in their measured section 1 amounts to approximately (2004b) in the northern Lucero uplift in the vicinity of Carrizo Arroyo. 628 m. A short distance to the north, still within Socorro County, There, the Abo Formation is about 150 m thick, consisting of red-bed Kelley and Wood’s (1946) section 2 (Monte de Belen) shows 490 m mudstone, arkosic sandstone and siltstone. The Yeso Group overlies of Sandia, Gray Mesa, and Atrasado, although the Sandia Formation the Abo Formation and is approximately 348 m thick. It can be divided portion of the section is incomplete. Kottlowski (1960) compiled into the DeChelly (70 m thick) and overlying Los Vallos (278 m thick) thickness estimates for Pennsylvanian strata in the Lucero uplift/ formations. The DeChelly Formation is dominantly beds of quartzose Sierra Ladrones area, including a reported value of about 823 m in the sandstone. The Los Vallos Formation is very fine-grained sandstone, southern Ladron Mountains a few km north of the Rio Salado (also siltstone, and gypsum, with some relatively thin but persistent marine see Siemers, 1978, 1983). Based on relatively high thickness estimates carbonate beds. The Glorieta Sandstone overlies the Yeso Group, is for the Pennsylvanian System in the Lucero uplift, Kottlowski (1960) approximately 53 m thick, and consists of quartzose sandstone and a followed previous workers (e.g., Wengerd, 1959) by delineating a single, 7 m thick bed of gypsum. It is conformably overlain by the San regional depocenter termed the Lucero basin on his Pennsylvanian Andres Formation, which is about 109 m thick and mostly gypsum and isopach maps. limestone, with lesser amounts of sandstone and shale. In the Lucero Since publication of the Kelley and Wood (1946) geologic uplift, the Middle Triassic Moenkopi Formation rests disconformably map and the Kottlowski (1960) compilation, reports that include on the San Andres Formation. lithostratigraphic descriptions of the Pennsylvanian strata in the Lucero Permian rocks in the Monte de Belen measured section of Kelley uplift/Sierra Ladrones area include Hammond’s (1987) M.S. thesis on and Wood (1946) were pieced together just north of the Socorro County 5 line. The section traverses large tracts mapped as Quaternary deposits 1975). Both Kottlowski (1960) and Siemers (1983) note that much of covering the Abo and Yeso portions of the section, and it appears the Atrasado Formation has been removed by faulting (tectonically that the upper part of the section extends outside the map area to the thinned) in the Magdalena Mountains. west. The graphic section depicts 268 m of Abo Formation, 32 m of Krainer and Lucas (2009) were convinced that the Abo Formation DeChelly Formation (their Meseta Blanca member) and 273 m of Los rests directly on the Atrasado Formation in the area around the Kelly Vallos Formation (total Yeso Group thickness of 305 m), together with Mine, so they show a zero thickness for the Bursum Formation in 66 m of Glorieta Sandstone and 137 m of San Andres Formation. The the Magdalena Mountains. Abo Formation strata are the youngest San Andres Formation in this traverse contains significant amounts of Paleozoic rocks exposed in the Magdalena Mountains and are much gypsum. faulted and intruded. Loughlin and Koschmann (1942) estimated that a maximum (but incomplete) Abo thickness of about 53 m is preserved Magdalena Mountains locally. Loughlin and Koschmann (1942) also listed records of both Pennsylvanian strata in the northern Magdalena Mountains are fusulinids and fossil plants from the Pennsylvanian and Permian strata the stratotype of Gordon’s (1907) Magdalena Group (Fig. 3), a term in the Magdalena Mountains, but these have not been examined by us. still used by some to refer to the entire Pennsylvanian section in Bell Hill (Southern San Mateo Mountains) southern New Mexico (though see Thompson [1942] and Kues [2001] for compelling arguments to abandon the term Magdalena Group). The southern San Mateo Mountains of Socorro County (Fig. 1) These strata are much faulted and otherwise altered by intrusives, so are a large volcanic edifice composed primarily of Eocene-Oligocene thickness estimates and some of the actual stratigraphic succession are igneous rocks at the eastern edge of the Mogollon-Datil volcanic field not definitely determined. Loughlin and Koschmann (1942) presented (e.g., McLemore, 2012). Along the southeastern edge of the range, the most detailed data and mapping of the upper Paleozoic section in relatively small fault blocks expose Paleozoic sedimentary rocks. One the Magdalena Mountains, and more recent summaries are provided by of these exposures, at Bell Hill (Fig. 1), has long been important to Kottlowski (1960) and Siemers (1978, 1983). the regional Pennsylvanian stratigraphy as the supposed thickest (~ The Pennsylvanian section has been assigned to the Sandia and 800 m thick) Pennsylvanian section in south-central New Mexico and Madera formations by these later workers, the latter divided into the the focal point of a late Paleozoic San Mateo depositional basin (e.g., gray limestone and overlying arkosic limestone members. We have Kottlowski, 1960; Furlow, 1965; Kelley and Furlow, 1965; Siemers, only examined these strata in a reconnaissance fashion, and assign 1978, 1983). them to the Sandia, Gray Mesa and Atrasado formations. According to In this volume, Lucas et al. (2017a) present the results of a Siemers (1978, 1983), the Sandia Formation is 167 m thick, the Gray restudy of the Pennsylvanian section at Bell Hill, and determine that Mesa 172 m thick, and the Atrasado Formation is only 61 m thick in it is thinner than previously reported, only 495 m thick. At Bell Hill, the Magdalena Mountains. This is a total thickness of about 400 m, but the Pennsylvanian strata overlie a thin (~ 70 m thick) lower Paleozoic Siemers (1983) states that well data suggest an actual thickness of the section that consists of the Cambro-Ordovician Bliss Formation Pennsylvanian section of 500-550 m (also see Krewedl, 1974; Siemers, and the Ordovician El Paso Group (Sierrite Member of the Hitt Canyon Formation) and Montoya Formation (Cable Canyon and Upham members). The Middle Pennsylvanian Red House Formation unconformably overlies the Montoya Formation, and is at least 31 m thick (structural complications prevent a certain estimate). It is overlain by the Gray Mesa Formation, which is 158 m thick and divisible into the Elephant Butte (at least 18 m thick), Whiskey Canyon (53 m thick) and Garcia (87 m thick) members. The overlying Bar B Formation is 306 m thick, substantially thicker than to the southeast, and accounts for most of the relatively great thickness of the Bell Hill Pennsylvanian section. The Bar B Formation is overlain by the Bursum Formation, ~ 26 m thick, which is overlain by the Abo Formation. Fusulinid and conodont biostratigraphy indicate that at Bell Hill the Red House Formation is Atokan, the Gray Mesa Formation is Desmoinesian and the Bar B Formation is Desmoinesian-Virgilian. The new estimate of the thickness of the Pennsylvanian section at Bell Hill (495 m) requires redrawing the late Paleozoic San Mateo basin as a platform–an area underlain by a relatively thick succession of Pennsylvanian strata, between the even thicker Pennsylvanian fill of the Lucero and Orogrande basins to the north and south (Fig. 4). Little San Pascual Mountains The Little San Pascual Mountains (LSPM) are a small uplift on the eastern side of the Rio Grande river, about 40 km south of Socorro (Fig. 1). Most of the sedimentary rocks exposed across the uplift are of Pennsylvanian age, overlain to the south-southeast by Permian strata (Kottlowski, 1960; Geddes, 1963; Siemers, 1978, 1983). In this volume, Lucas et al. (2017b) present new lithostratigraphic, petrographic and biostratigraphic data on the Pennsylvanian section in the LSPM. The Pennsylvanian section is at least 637 m thick and assigned to the (ascending order) Red House (200 m +), Gray Mesa (168 m) and Bar B (269 m) formations. The base of the Red House Formation is covered/faulted, so its thickness is a minimum. The Red House Formation in the LSPM consists of a lower interval of shale and limestone, a middle interval of shale and an upper interval of alternating shale and limestone. The overlying Gray Mesa Formation can be divided into Elephant Butte (45 m), Whiskey Canyon (37 m) and Garcia (87 m) members. The Elephant Butte Member is interbedded limestone and shale, the Whiskey Canyon Member is mostly cliff-forming, cherty limestone, and the Garcia Member is alternating limestone and covered intervals with a distinctive crossbedded sandstone at its base. The Bar B Formation is mostly slope-forming intervals that are covered/ shale alternating with limestone and dolomite. The Bursum Formation FIGURE 3. Gordon’s (1907) stratigraphy of the Magdalena Group in overlies the Bar B Formation and is 50-60 m of interbedded red-bed the Magdalena Mountains. mudstone, sandstone and limestone, overlain by siliciclastic red beds 6

FIGURE 4. Kottlowski’s (1960) isopach map of Pennsylvanian strata in south-central New Mexico identified a small San Mateo basin centered on Bell Hill (left) in Socorro and Sierra counties. New thickness data on the Pennsylvanian sections at Bell Hill and in the Little San Pascual Mountains redraw the thickness patterns so that the San Mateo basin is no longer evident; instead, there is a trough located on the platform separating the Lucero and Orogrande basins (right) (from Lucas et al., 2017a). of the Abo Formation. almost the same stratigraphic interval as Bursum Formation, the latter Conodont biostratigraphy indicates that in the LSPM, the Red has been generally used. Lucas and Krainer (2004) revived the name House Formation is of Atokan age, the Gray Mesa Formation is of Bruton as a member of the Bursum Formation at outcrops where most Atokan-Desmoinesian age and the Bar B Formation is of Desmoinesian- of its thickness is marine limestone and shale. Virgilian age. The Pennsylvanian section in the LSPM includes the On the northern end of the Oscura Mountains, a complete section northernmost outcrops of the Red House and Bar B formations. The of the Abo Formation is exposed, dipping under the Yeso Group section Bar B has a stratigraphic architecture that indicates it is transitional to that forms most of the flanks and lowlands of and around Chupadera Atrasado Formation sections to the north. Mesa (Wilpolt et al., 1946; Wilpolt and Wanek, 1951; DiMichele At 637+ m thick, the Pennsylvanian section in the LSPM is thicker et al., 2007). Here, the Abo Formation is ~ 150 m thick and almost than the Pennsylvanian section at Bell Hill. As already noted, these evenly divided into the Scholle and Cañon de Espinoso members. sections do not define a San Mateo basin of Pennsylvanian deposition, Fossil plants and tetrapod footprints are found at several levels in but instead identify a platform, between the Lucero and Orogrande the Cañon de Espinoso Member (DiMichele et al., 2007; Lucas and basins (Fig. 4). Spielmann, 2009a; Voigt and Lucas, 2017). The overlying Arroyo de Alamillo Formation of the Yeso Group is about 100-110 m thick but Northern Oscura Mountains poorly exposed in the lowlands southwest of Chupadera Mesa. It yields At the northern end of the Oscura Mountains in southeastern tetrapod tracks from sites in the lower 10 m of the formation (Voigt Socorro County (Fig. 1), a complete Pennsylvanian stratigraphic section and Lucas, 2017). As is the case east of Socorro, this section is one is overlain by an Abo Formation section that dips under the Yeso Group that documents the boundary between the Dromopus and Erpetopus strata that form the southwestern edge of Chupadera Mesa (Wilpolt biochrons, which is close to the Abo-Yeso boundary (Voigt and Lucas, and Wanek, 1951). The upper part of the Pennsylvanian section here is 2017). key to the regional Pennsylvanian lithostratigraphy because it contains Much of the upper Paleozoic section at the southern end of the the type sections of units named by Thompson (1942) that are now Oscura Mountains, at Mockingbird Gap on the White Sands Missile recognized as members of the Atrasado Formation (Figs. 2, 5-6) across Range, is in Socorro County, and it was described and mapped by much of Socorro County and as far north as the Sandia Mountains of Bachman (1968). We have mainly studied the Bursum, Abo and Yeso Bernalillo and Sandoval counties. strata in this area, publishing thus far only on the fossil footprints in the Lucas and Krainer (2009) provided the most recent description lower Yeso Group (Lucas and Spielmann, 2009b). of the Pennsylvanian section in the northern Oscura Mountains, assigning it to the Sandia, Gray Mesa and Atrasado formations. Here, Chupadera Mesa a thin Sandia Formation about 13 m thick rests nonconformably on Chupadera Mesa is a large tableland that extends from near Proterozoic granite, and is overlain by the limestone-dominated Gray Mountainair in Torrance County on the north to near Carrizozo in Mesa Formation, which is about 150 m thick. The overlying Atrasado Lincoln County on the south, a distance of about 86 km, most of it in Formation is ~ 121 m thick and is divided into the (ascending) Adobe, Socorro County (Fig. 1). The mesa is developed in early Permian rocks. Council Spring, Burrego, Story, Del Cuerto and Moya members, all of Lucas et al. (2016a) recently re-evaluated the Pennsylvanian which were units of formation rank in Thompson’s (1942) stratigraphy section to the west of Chupadera Mesa, in the southern Manzano (Fig. 5). Currently, three of us (SGL, KK and BDA) are restudying Mountains, most of it in Torrance County. This includes the type sections the Atrasado Formation section in the northern Oscura Mountains to of units named by Myers (1973) and long applied to Pennsylvanian improve both lithostratigraphic and biostratigraphic resolution. strata throughout the Manzano and Manzanita Mountains. Detailed At the northern end of the Oscura Mountains, the Bursum restudy indicates these strata are very similar to the Pennsylvanian Formation is about 80 m thick and includes the strata that were the type section in the Cerros de Amado, ~60 km to the SW, so the stratigraphic section of Thompson’s (1942) Bruton Formation. About 15 km to the nomenclature introduced by Thompson (1942) and elaborated by Rejas southwest, in the Hansonburg Hills, is the type section of the Bursum (1965) and Lucas et al. (2009a) can be applied to the Pennsylvanian Formation of Wilpolt et al. (1946), redescribed by Lucas et al. (2000, section in the Manzano and Manzanita Mountains (also see Lucas et 2002). Although Bruton Formation had priority over and refers to al., 2011a, 2014). 7

FIGURE 5. Thompson’s (1942) type sections of units he named for the upper part of the Pennsylvanian succession in the northern Oscura Mountains. Relatively recent regrading and excavation of the BNSF railroad and a few prominent beds of dolomite and gypsiferous sandstone. tracks through Abo Pass has cut fresh outcrops through most of the The overlying Cañas Member is 16-52 m thick, consisting mostly of Pennsylvanian section. Here, in the Burrego Member of the Atrasado gypsum and includes a few beds of gypsiferous siltstone and dolomite. Formation, an extensive paleoflora was collected and is detailed by The Joyita Member is ~ 21 m thick and consists of red-bed sandstone DiMichele et al. (2017b) in this volume. This is the only substantial that is crossbedded, ripple laminated and, in some beds, gypsiferous. paleoflora of Virgilian age known from Socorro County. The Glorieta Sandstone is ~ 78 m thick and consists of crossbedded, Lucas et al. (2016b) presented a comprehensive study of the laminar and ripple laminar, quartzose sandstone. In the Abo Pass area, Permian stratigraphic section at Abo Pass at the southern tip of the the upper part of the San Andres Formation has been eroded, leaving up Manzano Mountains and onto the western flank of Chupadera Mesa. to 91 m of mostly limestone (lime mudstone). It is overlain by Triassic Here, the Permian section is ~ 800 m thick and is assigned to the strata east of the Abo Pass area. Important tetrapod footprint localities (ascending order): Bursum Formation (Red Tanks Member), Abo in the Abo Formation (Voigt and Lucas, 2017) as well as vertebrate Formation (Scholle and Cañon de Espinoso members), Yeso Group bone localities in the Bursum and Abo formations (Berman et al., (Arroyo de Alamillo Formation and overlying Los Vallos Formation 2015) are just to the east of Abo Pass, in Torrance County (Lucas et al., divided into Torres, Cañas and Joyita members), Glorieta Sandstone 2016b). Fossil plants of Pennsylvanian and Permian age are also known and San Andres Formation. The Bursum Formation is ~ 35-40 m thick from the Abo Pass area (DiMichele et al., 2017a), though most of these and consists of interbedded red-bed siliciclastics (mudstone, sandstone localities are also in Torrance County. and conglomerate) and marine limestones. The Abo Formation is ~ 310 m thick and consists of siliciclastic red beds divided into the Los Pinos Mountains Scholle Member (~ 140 m of mudstone with channelized beds of The Los Pinos Mountains are part of a north-northeast chain of crossbedded sandstone and conglomerate) overlain by the Cañon de mountains that border the east side of the Rio Grande Valley (Fig. 1). Espinoso Member (~ 170 m of mudstone, siltstone and many thin Geologically, the range is a basement-cored uplift that formed along beds of sandstone that display climbing ripple lamination). The lower the eastern margin of the Rio Grande rift during the late Cenozoic. formation of the Yeso Group, the Arroyo de Alamillo Formation, In this uplift, above a thick and complex basement core, sedimentary consists of ~ 80 m of red-bed sandstone (mostly ripple laminar and rocks of late Paleozoic (Pennsylvanian-Permian) age are exposed. The laminar with some gypsiferous beds) and very minor dolomite. The complete Pennsylvanian section was described in a generalized way in overlying Torres Member of the Los Vallos Formation is ~ 180 m the older literature of New Mexico geology (Darton, 1922, 1928; Stark thick and mostly consists of gypsiferous siltstone, claystone, gypsum and Dapples, 1946). More recently, these rocks have been mapped at a 8

FIGURE 6. Bruton Canyon in the northern Oscura Mountains, looking west. This is the area Thompson (1942) used to define his stratigraphic nomenclature for Upper Pennsylvanian strata in New Mexico. A few of the cliff-forming members of the Atrasado Formation (originally designated as formations by Thompson) are labeled. scale of 1:24,000 (Myers et al., 1986; Allen et al., 2013a, 2014). Potentially, sedimentation during the Pennsylvanian and the early In this volume, Krainer et al. (2017b) present a new study of part of the early Permian in central New Mexico was influenced by the Pennsylvanian strata in the Los Pinos Mountains. These strata tectonic movements related to the ARM system, by glacio-eustatic nonconformably overlie Proterozoic metamorphic and granitic sea-level fluctuations related to the Gondwana glaciations and/or by basement and are disconformably overlain by the lower Permian climate fluctuations in what was then western equatorial Pangea, some Bursum Formation. Krainer et al. assign the approximately 424 m thick of which were far field effects of the late Paleozoic ice ages. Local Pennsylvanian section in the Los Pinos Mountains to the (ascending sedimentary processes were also influenced by local/regional climate order) Sandia (172 m thick), Gray Mesa (45 m thick) and Atrasado and topographic relief. These varied allocyclic and autocyclic drivers (206 m thick) formations. This section of the Sandia Formation is of sedimentation all played a role in late Paleozoic sedimentation in unusually thick, and fusulinids and conodonts demonstrate that its central New Mexico, but the work necessary to tease apart the different upper 80 m are of Desmoinesian age. Thus, at Sepultura Canyon, about drivers and their effects has only just begun. 80 m of Desmoinesian strata contain substantial beds of sandstone and In New Mexico, ARM tectonism created a series of intracratonic conglomerate. This distinguishes them from Desmoinesian strata to the uplifts of Pennsylvanian to Permian age, bounded by a number of north and south, which contain few or no beds of sandstone. This sandy sedimentary basins. The timing of uplift and basin subsidence varies interval thus indicates a local facies of Desmoinesian age not seen from basin to basin. In general, basins in northeastern to eastern New elsewhere in central New Mexico. This facies may be explained most Mexico subsided earlier (latest Mississippian to Early Pennsylvanian) easily by tectonic activity and proximity to the ARM Joyita uplift, over than basins in the southern and western part of New Mexico (climax which the Gray Mesa Formation pinches out (Kottlowki and Stewart, during the early Permian) (see summary in Kues and Giles, 2004). 1970; Nelson et al., 2013b, fig. 9). Two hypotheses have been developed to explain the tectonic Limestone of the unusually thin Gray Mesa Formation is processes of the ARM (Ye et al., 1996; Kluth, 1998; Dickinson and dominated by wackestone and floatstone with a diverse fossil Lawton, 2003). One explains the deformation by the collision of assemblage indicating deposition in a low-energy, open, normal marine Laurentia and Gondwana, resulting in the formation of the Ouachita shelf environment. The Atrasado Formation is composed of alternating orogen and the basins and uplifts of the ARM. The other hypothesis siliciclastic-dominated and limestone-dominated intervals that can be relates ARM deformation to northeasterly directed subduction along arranged in eight lithostratigraphic members that are recognizable over the southwestern margin of Laurentia evidenced by a volcanic arc a large part of central New Mexico. The Atrasado Formation is overlain in east-central Mexico. The interpretation of ARM deformation on a by siliciclastic redbeds at the base of the Bursum Formation. more regional scale is presented by Armstrong (1962), Armstrong and In the southern Los Pinos Mountains, Stark and Dapples (1946) Mamet (1988), Peterson (1980), Kluth and Coney (1981), Kluth (1986) named the Aqua Torres Formation (Aqua Torres is a corruption of and Woodward et al. (1999). Agua [de] Torres, the name of a local well) for a stratigraphic interval According to Kluth and Coney (1981), the late Paleozoic ARM about 61 m thick between the Atrasado and Abo formations that is uplifts and basins of Colorado, New Mexico and adjacent areas now assigned to the Bursum Formation (Krainer and Lucas, 2009). formed by NW-SE crustal shortening caused by the collision of North Allen et al. (2013b) described a Bursum section just south of the Los America with South America/Africa that produced the Ouachita- Pinos Mountains, where it is about 40 m thick and contains an early Marathon orogeny. This model is based on the assumption that north- Wolfcampian (Newwellian) assemblage of schwagerinid fusulinids. striking faults of late Paleozoic age underwent left-lateral slip, which Immediately south and east of the main part of the Los Pinos Mountains, is consistent with northwest-southeast crustal shortening. In contrast, Abo Formation and Yeso Group strata crop out but have not been Woodward et al. (1999) proposed that most of the 125 km of pre- studied by us. Laramide right-lateral offset in northern New Mexico occurred along north-trending major faults during the late Paleozoic. Late Paleozoic SEDIMENTATION: ANCESTRAL ROCKY MOUNTAIN deformation therefore was more likely caused by northeast-southwest TECTONICS, GLACIO-EUSTASY AND CLIMATE crustal shortening related to a northeast-directed subduction zone along Most students of late Paleozoic sedimentation in New Mexico the southwest margin of North America (Ye et al., 1996). posit glacio-eustasy and/or ARM tectonism as the principal drivers Glacio-eustatic sea-level fluctuations related to the Gondwana of sedimentation. Indeed, where discussed in this volume (see glaciation influenced sedimentation on tectonically stable shelfs such especially Krainer et al., 2017a, b; Nelson et al., 2017), the influence as the American Midcontinent, producing well developed cyclic of ARM tectonism on Pennsylvanian-Permian sedimentation is heavily successions. Cyclic sedimentation resulting from glacio-eustatic sea- emphasized. Little discussed, or considered, are the possible effects of level fluctuations has been reported from New Mexico, particularly from local or regional climate fluctuations on sedimentation. the Gray Mesa Formation (e.g., Soreghan 1994a, b; Scott and Elrick 9 2004; Wiberg 1993; Wiberg and Smith 1994) (also see discussion in members of the Atrasado Formation. These tectonic phases indicate Nelson et al., 2013a). Rygel et al. (2008) distinguished distinct phases rapid uplift of basement blocks and are separated by periods of of glacioeustatic sea-level fluctuations during the late Paleozoic, some tectonic quiescence during which limestone was deposited. The of which likely influenced sedimentation in central New Mexico. Bartolo Member represents the first tectonic phase during the latest The Sandia Formation encompasses the lower part of the Desmoinesian/earliest Missourian. The second phase during which the Pennsylvanian sedimentary succession across much of northern and Tinajas Member was deposited was the strongest and took place during central New Mexico, and represents synorogenic deposits related to the Missourian. The third tectonic phase is represented by the Burrego the onset of the ARM orogeny. Krainer and Lucas (2013) pointed out Member and occurred during the early Virgilian. The last tectonic phase that the Sandia Formation is characterized by marked lateral facies occurred during the late Virgilian. During this phase, which was the changes and variation in thickness. The Sandia Formation is generally weakest, the Del Cuerto Member was deposited. thin and dominantly siliciclastic in the northern part of New Mexico 4. Tectonic activity continued during deposition of the Bursum at sections close to the ARM uplifts, and becomes thicker towards the Formation (lower Wolfcampian), which contains substantial amounts south (Krainer and Lucas, 2013). of siliciclastic sediments, including nonmarine conglomerate and Tectonic activity during sedimentation of the Gray Mesa Formation arkosic sandstone. was comparatively low. The Whiskey Canyon Member in particular 5. The onset of deposition of the overlying nonmarine red is free of coarse siliciclastic deposits and almost free of fine-grained beds of the Abo Formation (and Cutler Group in northwestern New siliciclastic sediment, indicating that deposition took place during what Mexico) marks the last and strongest tectonic phase, causing uplift and may have been a relatively stable period tectonically. However, it may deposition of large amounts of siliciclastic sediments during the middle also reflect a period of relatively dry climate, when clastic runoff from and upper Wolfcampian, over large areas of New Mexico. nearby land surfaces was diminished. According to Krainer et al. (2017a) in this volume, the limestone- PALEONTOLOGY AND CORRELATION dominated members of the Atrasado Formation reflect periods of relative Fossil Plants tectonic quiescence, whereas the clastic-dominated members represent Plant fossils are abundant in strata of the Sandia, Atrasado, tectonically active periods during which rapid uplift of basement blocks Bursum, and Abo formations in Socorro County, both in the area east occurred. Based on these inferences, four tectonically active phases of Socorro and in other areas of the county where strata have been may have occurred during deposition of the Atrasado Formation. The investigated (e.g., Hunt, 1983; DiMichele et al., 2007, 2017a; Lucas et Tinajas Member marks the strongest, and the Del Cuerto Member, al., 2009b; Falcon-Lang et al., 2011, 2016). In this volume, DiMichele which contains only small amounts of siliciclastic sediment, represents et al. (2017b) describe numerous fossil floras from the Atrasado the weakest tectonic phase. Formation east of Socorro, encompassing more than 50 species ranging East of Socorro, the Bursum Formation is characterized by in age from late Desmoinesian to early Virgilian. The floral succession considerable lateral variations in facies and thickness, indicating that of the Atrasado Formation is important as a baseline study of vegetation regional synsedimentary tectonic movements of the ARM orogeny from the western Pangean equatorial region during the extensive time strongly influenced Bursum sedimentation (Krainer and Lucas, 2009). interval sampled. A tectonic pulse responsible for the unconformity at the base of the The floras are primarily allochthonous, with two notable Bursum Formation caused a sharp facies change from dominantly exceptions. One autochthonous flora has been described in detail by shallow marine carbonate sedimentation of the uppermost Atrasado Falcon-Lang et al. (2011, 2016). Of Missourian age, the plant fossils Formation to mixed siliciclastic-carbonate sedimentation of alternating consist of in situ silicified coniferopsid tree stumps and fallen logs of nonmarine and marine sediments of the Bursum Formation. The the same. These fossils are rooted in a micritic carbonate, and buried unconformity on top of the Bursum Formation was caused by a major in carbonate-rich, subaqueous to eolian-deposited gypsiferous dunes. tectonic pulse of the ARM deformation, resulting in a significant Elrick et al. (2017), in this volume, examine the sedimentary rejuvenation of basement uplifts and increased siliciclastic influx and features of this deposit and conclude that it formed in a sabkha setting, deposition of nonmarine red beds of the Abo Formation. but that the trees grew during a brief return to fresh-water conditions on There is also evidence for tectonic activity during sedimentation of an algal flat. The other autochthonous flora is of late Desmoinesian age, the Bursum Formation. The widespread Bursum Formation (Virgilian- and is dominated by stems and leaves of the pteridosperm Neuropteris early Wolfcampian) thus is the result of significant synsedimentary ovata, with only a few specimens of other species. Excavated in three tectonic activity related to the ARM orogeny. Glacioeustatic sea- locations, separated by up to 2.5 km, this deposit was likely a large, level changes related to the Permo-Carboniferous glaciation of the coastal swamp, the closest thing in the section to what, in the central Gondwana supercontinent seem to have been of minor importance portion of Pangea, would have been a coal bed. during sedimentation of the Bursum Formation and were overprinted In general aspect, the allochthonous floras of the Atrasado by tectonic movements (Krainer and Lucas, 2009; Lucas et al., 2013b; Formation are of a “mixed” character. They consist of species typical also see Nelson et al., 2017). of wetland habitats that were important elements of central Pangean In summary, following Krainer et al. (2017a), among others, coal basins of North America and Europe, intimately intermixed with several phases of the ARM orogeny can be distinguished in central New Mexico. The main source for siliciclastic sediment was the Pedernal species generally considered xeromorphic and tolerant of seasonally uplift, subordinately the Joyita uplift (Fig. 7). The biostratigraphy of dry settings. Included in this latter group are conifers, cordaitaleans, the Pennsylvanian succession in central New Mexico (e. g., Krainer and taeniopterids, noeggerathialeans, and some pteridosperms not usually Lucas, 2013, Nelson et al., 2013a, b; Lucas et al., 2016a, b, c) indicates found in wetlands. Such mixed floras indicate that the background the following timing of ARM tectonic phases: climate was likely seasonally dry, with the wetland elements living in 1. The Sandia Formation represents the first tectonic phase of local swamps and riverine corridors. the ARM orogeny during the Atokan, starting locally during the latest DiMichele and Lucas (2017), in this volume, describe the first Morrowan. occurrence of the calamitalean sphenopsid foliage Annularia from 2. The Gray Mesa Formation was deposited during a period the early Permian Abo Formation red beds east of Socorro. Although of little tectonic activity, although local intercalation of sandstone heavily sampled throughout its outcrop area from northern to south- and conglomerate in the lower (Elephant Butte) and upper (Garcia) central New Mexico, no calamitaleans have previously been reported members suggest some tectonic activity. This period of relative tectonic from the red beds of the Abo Formation. In light of the discovery of quiescence lasted for much of the Desmoinesian in most areas. It should this specimen, the authors discuss the matter of rarity in the living flora, be noted, though, that the Desmoinesian appears to be the time of the and contrast it with rarity in fossil assemblages. They conclude that highest sea level of the Middle Pennsylvanian with the lowest magnitude although rarity in the standing vegetation may be expected to translate of sea-level fluctuations until the very end. Thus, the Gray Mesa could into rarity in the fossil record, the latter may also result from a variety of be seen as being deposited during a time of globally high sea levels, taphonomic factors that may mask even abundant species in the parent and the overlying Bartolo Member of the Atrasado Formation could vegetation. be correlative with the extreme sea-level fluctuations that appeared Tetrapod Footprints during the late Desmoinesian throughout the entire equatorial area of Euramerica. This possibility, of course, diminishes the importance of Siliciclastic red beds of the Abo Formation and its homotaxial ARM tectonism in the onset of Atrasado Formation deposition. equivalents in New Mexico contain one of the World’s great records 3. Four tectonic phases may be recorded by the clastic-dominated of early Permian nonmarine trace fossils (e. g., Lucas and Heckert, 10

FIGURE 7. Isopach map of Pennsylvanian-Permian Bursum Formation and tectonic features of the ancestral Rocky Mountain orogeny in central New Mexico. 11 1995; Lucas et al., 2011a). East of Socorro, at Abo Pass and in the nucleation and mineralization of coprolites at the sediment-water northern Oscura Mountains, the Abo red beds (and, locally, the Arroyo interface was a function of possible microbial activity and prevailing de Alamillo Formation of the Yeso Group) contain a substantial number geochemical conditions such as iron and silica activity, pH, and oxygen of ichnofossil assemblages dominated by tetrapod footprints. fugacity of lake bottom water and sediment at the time of deposition. In this volume, Voigt and Lucas (2017) present the first Infilling of barite within the cracks of some coprolites represents either comprehensive review of these tetrapod ichnofaunas based on microbial sulfate reduction within the microenvironment of the original almost 500 track specimens. The fossil footprints are assigned to the fecal material or fault-related secondary mineralization that occurred ichnogenera Amphisauropus Batrachichnus, Dimetropus, Dromopus, long after deposition. Erpetopus, Hyloidichnus, Ichniotherium, Limnopus, Tambachichnium and Varanopus, and represent temnospondyl, reptiliomorph anamniote, Nonmarine Arthropods pelycosaurian-grade synapsid, eureptilian, and probable parareptilian In Socorro County, body fossils of nonmarine arthropods (notably trackmakers. Some rare and questionable tracks resemble Robledopus, conchostracans and insects) have been a byproduct of the search for Notalacerta, and Merifontichnus, and are traces of supposed early non- fossil plants in the Pennsylvanian strata east of Socorro. Notable, and diapsid eureptilian and therapsid origin. reported on earlier in a preliminary way (Martens and Lucas, 2005; The early Permian red beds of central New Mexico record the Lerner et al., 2009), is the black shale interval of the Tinajas Member turnover from the Dromopus biochron to the Erpetopus biochron (Voigt of the Atrasado Formation in the Cerros de Amado, which contains a and Lucas, 2017). The boundary of these two biochrons almost coincides prolific assemblage of conchostracans and much smaller numbers of with the lithostratigraphic boundary between the Abo Formation and other arthropods, notably blattoids (cockroaches). the overlying Arroyo de Alamillo Formation, and this boundary is, In this volume, Schneider et al. (2017) describe fossil insects from according to the global Permian tetrapod footprint record, not older the Bartolo and the Tinajas members of the Atrasado Formation east of than late Artinskian in age. Moreover, the early Permian ichnofauna of Socorro. Particularly interesting is a relatively small collection of fossil the Abo Formation in Socorro County statistically confirms previous insects from lacustrine black shales of the Tinajas Member. Most of them hypotheses (e. g., Hunt and Lucas, 2006) that reptiliomorph anamniote are blattoids, but they include one blattinopsid. The blattoids belong tracks (Amphisauropus, Ichniotherium) are more common in inland to the genus Sysciophlebia of the family Spiloblattinidae, the genera deposits, and small temnospondyl (Batrachichnus) and pelycosaurian- Phyloblatta and Anthracoblattina of the family Phyloblattidae, as well grade synapsid (Dimetropus) tracks dominate coastal plain deposits. as to the genera Dictiomylacris, Opsiomylacris and Neorthroblattina of the family Mylacridae. The insect-bearing horizons in the Atrasado Coprolites Formation are bracketed by marine limestones that contain conodonts, East of Socorro, the Tinajas Member of the Atrasado Formation which allow for correlation of the nonmarine-insect-bearing strata to yields prolific assemblages of coprolites, first discussed by Hunt et al. the Standard Global Chronostratigraphic Scale. The occurrence of (2012). In this volume, both Hunt and Lucas (2017) and Harris et insect biozone species in the Tinajas Member indicates that the range al. (2017) present analysis of extensive coprolite assemblages from the of the Sysciophlebia rubida-Syscioblatta lawrenceana insect zone is Tinajas Member. middle Kasimovian to early Gzhelian in age. Based on this, Schneider Hunt and Lucas (2017) document a new coprolite locality et al. hypothesize that the gypsum-bearing evaporitic deposits in the (named the Erickson site) in the Tinajas Member that contains a very Atrasado Formation may partly correspond to a phase of drier climate large sample of coprolites. Most specimens are found as a weathered with widespread development of red beds containing vertic and calcic lag that eroded from a shale, although a small number of specimens aridisol horizons in the middle Kasimovian to middle Gzhelian of occur in situ in thin limestone beds. Most of the coprolites are spiral Europe in eastern Laurasia. It is worth noting that similar indicators of in morphology (heteropolar, amphipolar, scroll). Six ichnotaxa are more moisture-limited conditions are present in the Appalachian Basin heteropolar spiral in morphology and include a new ichnotaxon, during the Missourian, at about this same time period, resulting in the Crassocoprus mcallesteri, Kalocoprus oteroensis, Heteropolacopros appearance of numerous floras dominated by coniferophytes and other texaniensis and Speirocoprus isp. There are numerous specimens of xeromorphic taxa (e.g., Bassler, 1916; McComas, 1988; Lyons and Crassocoprus mcallesteri, and amphipolar coprolites are represented Darrah, 1989; Martino, 2017) by Hyronocopros amphipola. There are several specimens of the scroll What is currently known of the Pennsylvanian record of insects coprolite Bibliocoprus beemanensis, which is identified outside of its east of Socorro is very limited. No doubt field efforts to specifically type locality for the first time. collect fossil insects would add substantially to what is now known of Hunt and Lucas (2017) note that there are four bromalite the Pennsylvanian insects in the area east of Socorro. assemblages of Missourian age in New Mexico that represent an ecological transect from lacustrine to basinal marine: (1) Tinajas Vertebrate Fossils Lagerstätte – lacustrine; (2) Kinney Brick Quarry Lagerstätte – lagoonal; Vertebrate fossils are found throughout much of the upper Paleozoic (3) Erickson site – nearshore marine; and (4) Sacramento Mountains – section east of Socorro, but are only concentrated and abundant in the offshore marine. There are clear trends through these ichnoassemblages Abo Formation. In this volume, Harris and Lucas (2017) describe a (Tinajas-Kinney-Erickson-Sacramentos): (1) flattened preservation in large skull of an actinopterygian fish from Pennsylvanian strata east matrix to isolated three dimensional; (2) diverse bromalites to only of Socorro. Hodnett and Lucas (2017) review the record of fossil coprolites; and (3) increasing proportion of spiral coprolites. The fishes from the Sandia, Atrasado, Bursum and Abo formations east of Erickson locality is transitional in all these aspects between Tinajas Socorro. These are mostly of selachians from marine facies (e.g., Zidek and the Sacramentos. The ichnoassemblage of the Beeman Formation and Kietzke, 1993; Lucas and Estep, 2000; Ivanov et al., 2009; Itano is representative of the shark surplus paradox, in which there is an and Lucas, 2015; Hodnett and Lucas, 2015). However, both the Bursum apparent disproportionate diversity and abundance of spiral (probably and Abo formations contain some nonmarine fish fossils. chondrichthyan) coprolites relative to the fish fauna (preserved or According to Hodnett and Lucas (2017), the upper Paleozoic inferred). The Kinney ichnoassemblage is typical of lagoonal/estuarine strata of Socorro County preserve a series of four distinct environmental ichnofaunas of the Paleozoic and Mesozoic. phases and their corresponding fish assemblages from the Middle Harris et al. (2017) document a rare, laterally extensive nonmarine Pennsylvanian through the early Permian: (1) a Middle Pennsylvanian coprofauna preserved in lacustrine sediments of the Tinajas Member of marine phase, (2) a Late Pennsylvanian short marine regression/coastal the Atrasado Formation east of Socorro. Here, abundant coprolites from lacustrine phase, (3) a latest Pennsylvanian/earliest Permian short five recently discovered localities in the Tinajas black shale interval marine transgression, and (4) an early Permian freshwater fluvial phase. are distinguished from those of the stratigraphically equivalent Tinajas Many of the late Paleozoic Socorro fish assemblages are dominated by Lagerstätte by their large size and three-dimensional preservation. isolated shark teeth. Rigorous field collection of macro specimens and Together, the Tinajas black shale coprolites represent a remarkable screen washing programs could greatly expand the taxa and data of the record of morphological and preservational variation within the context Socorro fish assemblages. of a single paleolake system. Three coprolite taphotypes are recognized: Northeast of Socorro, vertebrate body fossils (and coprolites) (1) enclosure within a goethite concretionary layer; (2) cementation from the Abo Formation are best known at the Gallina Well locality, within a quartz-rich mantle; and (3) non-concretionary hydroxylapatite stratigraphically low in the Scholle Member (Berman and Reisz, 1986; permineralization. X-ray diffraction analysis (XRD) was used to Berman, 1993; Harris et al., 2005; Spielmann et al., 2009; Cantrell et determine the mineralogical composition of a representative sample al., 2011, 2012, 2013; Berman et al., 2015). The collective vertebrate- of coprolites from each taphotype. Early diagenetic (pre-compaction) fossil assemblage from this locality consists of palaeonisciform fishes; 12 the temnospondyl amphibians Eryops, Trimerorhachis, Zatrachys and Platyhystrix; captorhinimorphs; the lepospondyl Diplocaulus; and the eupelycosaurs Ophiacodon, Sphenacodon and Dimetrodon. This is a tetrapod-dominated assemblage of the Coyotean land-vertebrate faunachron, which is of latest Virgilian-middle Wolcampian age (Lucas, 2006, 2017). Marine Microfossils Marine microfossils from the Sandia, Gray Mesa, Atrasado and Bursum formations in Socorro County are primarily cyanobacteria, algae, foraminiferans (including fusulinids) and conodonts. The conodonts have already been documented by Lucas et al. (2009a) and Barrick et al. (2013) for the area east of Socorro. In this volume, Lucas et al. (2017b) document conodonts from Bell Hill, and Krainer et al. (2017a) document them from the Los Pinos Mountains. These conodont records provide some precise correlations of the marine strata, notably matching parts of the Atrasado Formation east of Socorro to mid-continent cyclothems (Fig. 8), but much more remains to be done in terms of sampling and studying Pennsylvanian-Permian conodonts from Socorro County. In the Los Pinos Mountains and Cerros de Amado region, cyanobacteria occur as encrusting organisms on various skeletal grains, locally forming coated grains and oncoids in many limestones of the Sandia, Gray Mesa and Atrasado formations. Thin microbial mats (stromatolites) are present, and, locally, cyanobacteria and other encrusting organisms form small patches of boundstone in the Tinajas Member (Krainer et al., 2017a, b). Cyanobacteria are also present in many limestones of the Red House, Gray Mesa and Bar B formations of the Little San Pascual Mountains (Lucas et al., 2017b) and in the Bar B Formation at Bell Hill (Lucas et al., 2017a). Cyanobacteria are also present in the Torres Member of the Los Vallos Formation (Yeso Group) east of Socorro, locally forming cm-sized oncoids (Lucas and Krainer, 2017). In the San Andres Formation, cyanobacteria are common, forming stromatolites (Lucas and Krainer 2017). Calcareous (mostly phylloid) algae are common in many limestone beds of the Gray Mesa and Atrasado formations, in part forming phylloid algal wackestone and floatstone. Other algae are subordinate, such as Eugonophyllum, Archaeolithophyllum missouriense, Anthracoporella (Garcia Member), Epimastopora (Amado Member), Efluegelia (Whiskey Canyon, Garcia members) and Claracrusta (Bartolo Member) (Krainer et al., 2017a, b). In the Little San Pascual Mountains, phylloid algae are common in limestones of the Red House, Gray Mesa and Bar B formations. Archaeolithophyllum missouriense is rarely found in the Red House Formation, and Komia is rare in the Gray Mesa Formation (Lucas et al., 2017b). At Bell Hill, phylloid algae are common in the Gray Mesa and Bar B formations, Archaeolithophyllum missouriense occurs in the Gray Mesa Formation and Komia is rarely present in the Gray Mesa and Bar B formations (Lucas et al., 2017a). Phylloid algae are also present in some limestone beds of the Bursum Formation, but less common than in the underlying Pennsylvanian limestones. In the San Andres Formation, some limestone beds contain abundant recrystallized calcareous algae (algal wackestones) (Lucas and Krainer, 2017). Smaller benthic foraminifers are present in almost all limestones of the Sandia, Gray Mesa and Atrasado formations in the Los Pinos Mountains and the Cerros de Amado region. They are present in all microfacies, except in peloidal wackestone, packstone, grainstone and mudstone. The diversity is lower in the Sandia Formation than in the Gray Mesa and Atrasado formations (Krainer et al., 2017a, b). The most common smaller foraminifers are species of Eotuberitina, Tuberitina, Earlandia, Endothyra, Planoendothyra, Bradyina, Climacammina, Deckerella, Spireitlina, Tetrataxis, Polytaxis, Globivalvulina, Calcivertella, Ammovertella, Palaeonubecularia, Hemigordiellina, Syzrania, and Syzranella, which are partly documented in Krainer et al. (2017b). Smaller foraminifers are also present in limestones of the Red House, Gray Mesa and Bar B formations of the Little San Pascual Mountains (Lucas et al., 2017b) and at Bell Hill (Lucas et al., 2017a). The diversity of smaller foraminifers in the Bursum Formation is less than in the Pennsylvanian limestones. Smaller benthic foraminifers are rare in the Yeso Group (Torres Member of the Los Vallos Formation). Limestones of the San Andres Formation east of Socorro contain a low diversity association of smaller foraminifers (Lucas and Krainer, 2017). Fusulinids are present in some limestones of the Sandia Formation FIGURE 8. Correlation of the Atrasado Formation east of Socorro (Fusulinella), Gray Mesa Formation (Beedeina, Wedekindellina, based on conodont biostratigraphy (modified from Barrick et al., 2013). Plectofusulina, rare Eoschubertella and Millerella) and Atrasado Formation (various species of Triticites) in the Los Pinos Mountains 13 and Cerros de Amado (Krainer et al., 2017a, b). Fusulinids are present Berman, D. S, 1993, Lower Permian vertebrate localities of New Mexico and in some limestones of the Red House, Gray Mesa and Bar B formations their assemblages: New Mexico Museum of Natural History and Science, of the Little San Pascual Mountains, but were not studied in detail Bulletin 2, p. 11-21. (Lucas et al., 2017a). At Bell Hill, fusulinids occur in the Red House Berman, D. S and Reisz, R. R., 1986, Captorhinid reptiles from the lower Formation (including Millerella), the Gray Mesa Formation (species of Permian of New Mexico, with description of a new genus and species: Beedeina and Wedekindellina) and Bar B Formation (various species of Annals of Carnegie Museum, v. 55, p. 1-28. Triticites) (documented in Lucas et al., 2017b). Some limestones of the Berman, D.S., Henrici, A.C., Lucas, S.G., 2015. Pennsylvanian-Permian red bed Bursum Formation in the Little San Pascual Mountains contain large vertebrate localities of New Mexico and their assemblages: New Mexico Triticites (Lucas et al., 2017a). Museum of Natural History and Science, Bulletin 68, p. 65-76. Cantrell, A. K., Suazo, T. L., Spielmann, J. A. and Lucas, S. G., 2012, Vertebrate Marine Macrofossils coprolites from the lower Permian (middle Wolfcampian) Gallina Well Marine macrofossil faunas of the Sandia, Gray Mesa, Atrasado, locality, Joyita Hills, Socorro County, New Mexico: New Mexico Museum Bursum and San Andres formations fossils are dominated by the of Natural History and Science, Bulletin 57, p. 197-201. characteristic shelly benthos of the late Paleozoic, namely brachiopods, Cantrell, A. K., Suazo, T. L., McKeighen, K. L., Jr., McKeighen, H. W., crinoids and bryozoans. Molluscs (mostly bivalves and gastropods) are Lucas, S. G., Harris, S. K., Spielmann, J. A., and Rinehart, L. F., 2011, much less common. Little effort has been made to collect and publish Dimetrodon (Eupelycosauria: Sphenacodontidae) from the lower Permian on these fossils, one of the few exceptions being Kues (2002). These Abo Formation, Socorro and Torrance counties, New Mexico: New fossils have been too little studied in the New Mexico upper Paleozoic Mexico Museum of Natural History and Science, Bulletin 53, p. 34-37. section to provide a detailed biostratigraphy. They provide some Cantrell, A.K., Suazo, T.L., Berman, D.S, Spielmann, J.A., Lucas, S.G., Henrici, paleoecological data, but need much more collecting and study. A.C. and Rinehart, L.F., 2013, The Gallina Well locality, an early Permian (middle Wolfcampian) vertebrate and trace fossil site in Socorro County, PROSPECTUS New Mexico: New Mexico Museum of Natural History and Science, This volume documents extensive and diverse research on the Bulletin 59, p. 253-264. Pennsylvanian-Permian rocks and fossils in Socorro County. As Darton, N. H., 1922, Geologic structure of parts of New Mexico: U. S. Geological detailed as some of the data and analyses presented here are, all of the Survey, Bulletin 726, p. 173-275. upper Paleozoic outcrops in Socorro County merit further research, Darton, N. H., 1928, “Red beds” and associated formations in New Mexico with particularly to refine further their biostratigraphy and correlation. The an outline of the geology of the state: U. S. Geological Survey, Bulletin two decades of research reported here thus can be considered a strong 794, 356 p. start to a much needed detailed study of the stratigraphy, sedimentology Dickinson, W. R. and Lawton, T. E., 2003, Sequential intercontinental suturing and paleontology of the upper Paleozoic rocks and fossils of New as the ultimate control for Pennsylvanian Ancestral Rocky Mountains Mexico. deformation: Geology, v. 31, p. 609-612. DiMichele, W. A. and Lucas, S. G., 2017, The first specimen of Annularia ACKNOWLEDGMENTS spinulosa Sternberg from the lower Permian Abo Formation, New Mexico, The work reported in this paper was assisted by too many people and implications for rarity in the plant fossil record: New Mexico Museum to name here. Most notable are Scott Elrick and John Nelson for diverse of Natural History and Science, Bulletin 77, this volume. collaboration on geological issues; Dan Chaney for collecting plant DiMichele, W.A., Lucas, S.G., Looy, C.V., Kerp, H. and Chaney, D., 2017a, Plant fossils; Jim Barrick for conodont biostratigraphy; Daniel Vachard for fossils from the Pennsylvanian–Permian transition in western Pangea, Abo his work on calcareous microfossils and their biostratigraphy; Sebastian Pass, New Mexico: Smithsonian Contributions to Paleobiology 99, p. 1-40. Voigt, Adrian Hunt, Susan Harris and Allen Lerner for their work on DiMichele, W. A., Chaney, D. S., Lucas, S. G., Nelson, W. J., Elrick, S. D., trace fossils; and Joerg Schneider for his studies of fossil insects. Staff Falcon-Lang, H. J. and Kerp, H., 2017b, Middle and Late Pennsylvanian and volunteers of the New Mexico Museum of Natural History provided fossil floras from Socorro County, New Mexico, U.S.A: New Mexico diverse field assistance, notably Amanda Cantrell, Sebastian Dalman, Museum of Natural History and Science, Bulletin 77, this volume. Alan Erickson, Larry Rinehart, Justin Spielmann and Tom Suazo. DiMichele, W. A., Chaney, D. S., Nelson, W. J., Lucas, S. G., Looy, C. V., Quick, K. and Wang, J., 2007, A low diversity, seasonal tropical landscape REFERENCES dominated by conifers and peltasperms: Early Permian Abo Formation, Allen, B. D., Love, D. W. and McCraw, D. J., 2013b, Uppermost Pennsylvanian New Mexico: Review of Palaeobotany and Palynology, v. 145, p. 249–273. 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L., 1904, Laws of formation of New Mexico mountain ranges: Socorro County, New Mexico: New Mexico Museum of Natural History American Geologist, v. 33, p. 301-312. and Science, Bulletin 77, this volume. Hodnett, J-P. M. and Lucas, S. G., 2015, Paleozoic fishes of New Mexico: A Krewedl, D. A., 1974, Geology of the central Magdalena Mountains, Socorro review: New Mexico Museum of Natural History and Science, Bulletin County, New Mexico [Ph.D. thesis]: Tucson, University of Arizona, 138 p. 68, p. 51-63. Kues, B. S., 2001, The Pennsylvanian System in New Mexico—overview with Hodnett, J-P. M. and Lucas, S. G., 2017, Paleoichthyological assemblages of suggestions for revision of stratigraphic nomenclature: New Mexico the Upper Carboniferous-lower Permian of Socorro County, New Mexico: Geology, v. 23, p. 103-122. New Mexico Museum of Natural History and Science, Bulletin 77, this Kues, B. S., 2002, Invertebrate paleontology of the Bursum Formation type volume. section (latest Pennsylvanian), Socorro County, New Mexico: New Hunt, A., 1983, Plant fossils and lithostratigraphy of the Abo Formation (lower Mexico Geological Society, Guidebook 53, p. 193-209. Permian) in the Socorro area and plant biostratigraphy of Abo red beds in Kues, B. S. and Giles, K. A., 2004, The late Paleozoic ancestral Rocky New Mexico: New Mexico Geological Society, Guidebook 34, p. 157-163. Mountains system in New Mexico: New Mexico Geological Society, Hunt, A.P. and Lucas, S.G., 2006, Permian tetrapod ichnofacies: Geological Special Publication 11, p. 95-136. Society London, Special Publications, v. 265, p. 137–156. Lee, W. T., 1909, The Manzano group of the Rio Grande Valley, New Mexico. Hunt, A. P. and Lucas, S. G., 2017, A new vertebrate coprolite locality from the Stratigraphy of the Manzano Group: U. S. Geological Survey, Bulletin Late Pennsylvanian of central New Mexico, USA, and the environmental 389, p. 5-40. context and biochrononology of Carboniferous and Permian bromalites: Lerner, A. J and Lucas, S. G., 2017, The pseudofossil Astropolithon from the New Mexico Museum of Natural History and Science, Bulletin 77, this lower Permian Abo Formation of Socorro County, central New Mexico: volume. New Mexico Museum of Natural History and Science, Bulletin 77, this Hunt, A.P., Lucas, S.G., Cotton, W., Cotton, J. and Lockley, M.G., 1995, Early volume. Permian vertebrate tracks from the Abo Formation, Socorro County, Lerner, A.J., Lucas, S.G., Spielmann, J.A., Krainer, K., Dimichele, W.A., central New Mexico: A preliminary report: New Mexico Museum of Chaney, D.S., Schneider, J.W., Nelson, W.J., and Ivanov, A., 2009, The Natural History and Science, Bulletin 6, p. 263–268. biota and paleoecology of the Upper Pennsylvanian (Missourian) Tinajas Hunt, A. P., Lucas, S. G., Spielmann, J. A., Cantrell, A., Suazo, T. and Lerner, A. Locality, Socorro County, New Mexico: New Mexico Geological Society, J, 2012, Bromalites from the Tinajas Lagerstätte (Late Pennsylvanian: Late Guidebook 60, p. 267-280. Missourian), central New Mexico, USA: New Mexico Museum of Natural Loughlin, G. H. and Koschmann, A. H., 1942, Geology and ore deposits of History and Science, Bulletin 57, p. 175-183. the Magdalena mining district, New Mexico: U. S. Geological Survey, Itano, W.M., and Lucas, S.G., 2015, Campyloprion (Chondrichthyes, Edestoidea) Professional Paper 200, 168 p. from the Upper Pennsylvanian of Socorro County, New Mexico: New Lucas, S. G., 2006, Global Permian tetrapod biostratigraphy and biochronology: Mexico Geological Society, Annual Spring Meeting Abstract Volume, p. Geological Society, London, Special Publications 265, p. 65-93. 29. Lucas, S. G., 2017, Permian tetrapod biochronology, correlation and evolutionary Ivanov, A., Lucas, S.G., and Krainer, K., 2009, Pennsylvanian fishes from the events: Geological Society, London, Special Publications 460, in press. Sandia Formation, Socorro County, New Mexico: New Mexico Geological Lucas, S.G. and Estep, J.W., 2000, Pennsylvanian selachians from the Cerros de Society, Guidebook 60, p. 243-248. Amado, central New Mexico: New Mexico Museum of Natural History Kelley, V. C. and Furlow, J. W., 1965, Lower Paleozoic wedge edge in south- and Science, Bulletin 16, p. 21-27. central New Mexico: New control: Geological Society of America Lucas, S.G., and Heckert, A.B., eds., 1995, Early Permian footprints and facies: Bulletin, v. 76, p. 689-694. New Mexico Museum of Natural History and Science, Bulletin 6, 301 p. Kelley, V.C., and Wood, G.H., 1946, Lucero uplift, Valencia, Socorro, and Lucas, S.G. and Krainer, K., 2004, The Red Tanks Member of the Bursum Bernalillo Counties, New Mexico: U.S. Geological Survey, Oil and Gas Formation in the Lucero uplift and regional stratigraphy of the Bursum Investigations Preliminary Map 47, scale 1:63,360. Formation in New Mexico: New Mexico Museum of Natural History and Kluth, C. F., 1986, Plate tectonics of the Ancestral Rocky Mountains: American Science, Bulletin 25, p. 43-52. Association of Petroleum Geologists, Memoir 41, p. 353-369. Lucas, S. G. and Krainer, K., 2009, Pennsylvanian stratigraphy in the northern Kluth, C. F., 1998, Late Paleozoic deformation of interior North America: The Oscura Mountains, Socorro County, New Mexico: New Mexico Geological greater Ancestral Rocky Mountains: Discussion: American Association of Society, Guidebook 60, p. 153-166. Petroleum Geologists Bulletin, v. 82, p. 2272-2276. Lucas, S. G. and Krainer, K., 2017, The Permian System east of Socorro, Kluth, C. F. and Coney, P. J., 1981, Plate tectonics of the Ancestral Rocky central New Mexico (USA): New Mexico Museum of Natural History and Mountains: Geology, v. 9, p. 10-15. Science, Bulletin 77, this volume. Kottlowski, F. E., 1960, Summary of Pennsylvanian sections in southwestern Lucas, S. G. and Spielmann, J.A., 2009a, Tetrapod footprints from the lower New Mexico and southeastern Arizona: New Mexico Bureau of Mines and Permian Abo Formation near Bingham, Socorro County, New Mexico: Mineral Resources, Bulletin 66, 187 p. New Mexico Geological Society, Guidebook 60, p. 299–304. Kottlowski, F.E. and Stewart, W.J., 1970, The Wolfcampian Joyita uplift Lucas, S.G. and Spielmann, J.A., 2009b, Tetrapod footprints from the lower in central New Mexico: New Mexico Bureau of Mines and Mineral Permian Yeso Group, Mockingbird Gap, Socorro County, New Mexico: Resources, Memoir 23, p. 1-31. New Mexico Geological Society, Guidebook 60, p. 305–310. Krainer, K. and Lucas, S.G., 2004a, Type sections of the Pennsylvanian Gray Lucas, S. G. and Zeigler, K. E., eds., 2004a, Carboniferous-Permian transition Mesa and Atrasado formations, Lucero uplift, central New Mexico: New at Carrizo Arroyo, central New Mexico: New Mexico Museum of Natural Mexico Museum of Natural History and Science, Bulletin 25, p. 7-30. History and Science, Bulletin 25, 300 p. Krainer, K. and Lucas, S.G., 2004b,The Upper Pennsylvanian Red Tanks Lucas, S.G., and Zeigler, K.E., 2004b, Permian stratigraphy in the Lucero Member of the Bursum Formation at Carrizo Arroyo, central New Mexico: uplift, central New Mexico: New Mexico Museum of Natural History and Transition from shallow marine to nonmarine facies: New Mexico Museum Science, Bulletin 25, p. 71-82. of Natural History and Science, Bulletin 25, p. 53-69. Lucas, S.G., Krainer, K. and Barrick, J.E., 2009a, Pennsylvanian stratigraphy Krainer, K. and Lucas, S.G., 2009, Cyclic sedimentation of the Upper and conodont biostratigraphy in the Cerros de Amado, Socorro County, Pennsylvanian (lower Wolfcampian) Bursum Formation, central New New Mexico: New Mexico Geological Society, Guidebook 60, p. 183-212. Mexico: Tectonics versus glacioeustasy: New Mexico Geological Society, Lucas, S. G., Krainer, K. and Kues, B. S., 2002, Type section of the Upper 15 Carboniferous Bursum Formation, south-central New Mexico, and the 59, p. 123-142. Bursumian Stage: New Mexico Geological Society, Guidebook 53, p. 179- Nelson, W. D., Elrick, S. D., Krainer, K. and Lucas, S. G., 2017, Facies changes 192. in the Bursum Formation (Pennsylvanian-Permian) related to tectonic Lucas, S.G., Krainer, K. and Vachard, D., 2016a, The Pennsylvanian section at activity, Socorro area, New Mexico: New Mexico Museum of Natural Priest Canyon, southern Manzano Mountains, New Mexico: New Mexico History and Science, Bulletin 77, this volume. Geological Society Guidebook 67, p. 275-301. Peterson, J.A., 1980, Permian paleogeography and sedimentary provinces, west- Lucas, S.G., Barrick, J.E., Krainer, K., and Schneider, J.W., 2013b, The central United States; in Fouch, T. D. and Magathan, E. R., eds., Paleozoic Carboniferous-Permian boundary at Carrizo Arroyo, central New Mexico, paleogeography of west-central United States: Society of Economic USA: Stratigraphy, v. 10, p. 153-170. Paleontologists and Mineralogists, Rocky Mountain Section, Symposium Lucas, S. G., Krainer, K., Allen, B. D. and Barrick, J. 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