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New Mexico Geological Society Downloaded from: http://nmgs.nmt.edu/publications/guidebooks/33 Stratigraphic summary of Pennsylvanian and Lower Permian rocks, Manzano Mountains, New Mexico Donald A. Myers, 1982, pp. 233-237 in: Albuquerque Country II, Wells, S. G.; Grambling, J. A.; Callender, J. F.; [eds.], New Mexico Geological Society 33rd Annual Fall Field Conference Guidebook, 370 p. This is one of many related papers that were included in the 1982 NMGS Fall Field Conference Guidebook. Annual NMGS Fall Field Conference Guidebooks Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscience papers. These books have set the national standard for geologic guidebooks and are an essential geologic reference for anyone working in or around New Mexico. Free Downloads NMGS has decided to make peer-reviewed papers from our Fall Field Conference guidebooks available for free download. Non-members will have access to guidebook papers two years after publication. Members have access to all papers. This is in keeping with our mission of promoting interest, research, and cooperation regarding geology in New Mexico. However, guidebook sales represent a significant proportion of our operating budget. Therefore, only research papers are available for download. Road logs, mini-papers, maps, stratigraphic charts, and other selected content are available only in the printed guidebooks. Copyright Information Publications of the New Mexico Geological Society, printed and electronic, are protected by the copyright laws of the United States. No material from the NMGS website, or printed and electronic publications, may be reprinted or redistributed without NMGS permission. Contact us for permission to reprint portions of any of our publications. One printed copy of any materials from the NMGS website or our print and electronic publications may be made for individual use without our permission. Teachers and students may make unlimited copies for educational use. Any other use of these materials requires explicit permission. This page is intentionally left blank to maintain order of facing pages. New Mexico Geological Society Guidebook, 33rd Field Conference, Albuquerque Country II, 1982 233 STRATIGRAPHIC SUMMARY OF PENNSYLVANIAN AND LOWER PERMIAN ROCKS, MANZANO MOUNTAINS, NEW MEXICO DONALD A. MYERS U.S. Geological Survey Box 25046, Mail Stop 918 Federal Center Denver, Colorado 80225 INTRODUCTION in the upper 6 m. The uppermost beds are medium- to dark-gray shaly The Manzano Mountains (fig. 1) are east of the Rio Grande Valley and sandy limestone with partings of calcareous shale and siltstone; between 1-40 and U.S. 60. The Manzano Mountains are a fault-block lenses of brown chert are common. The fusulinid Fusulinella famula range about 16 km wide and 72 km long. The western part of the range is common in the uppermost beds of the Sandia. has been uplifted along mostly concealed north-trending faults to On the basis of the contained fusulinids, the age of the Sandia is expose a core of Precambrian metasedimentary, metavolcanic, and Atokan. There is no evidence that the Sandia includes rocks of Mor- crystalline rocks. The Albuquerque basin is downfaulted relative to the rowan age in the Manzano Mountains. uplift. The eastern part of the range is a gently sloping surface formed by MADERA GROUP Pennsylvaniän rocks that dip eastward beneath overlying surficial de- posits. The Pennsylvanian rocks, at most places, overlie the Precam- The Madera Group (Myers, 1973) in the Manzano Mountains in- brian; however, at a few localities, remnants of Mississippian rocks cludes rocks tht were formerly assigned to the Madera Limestone of that are less than 4 m thick rest on the Precambrian. Read and others (1944) and to the Bursum Formation. The Madera Group, as now defined for this region (fig. 2), includes the Los Moyos The Pennsylvanian and Lower Permian marine, marginal marine, Limestone, mostly cliff-forming beds of limestone; the Wild Cow For- and terriginous rocks (fig. 2) have been subdivided into the Sandia mation, a sequence of alternating beds of sandstone, shale, and lime- Formation (Atokan) and the overlying Madera Group. The Madera stone; and the Bursum Formation, a sequence of red beds and marine Group is subdivided, in ascending order, into the Los Moyos Limestone limestone at the southern end of the mountains. The Madera Group (Des Moinesian and Missourian), the Wild Cow Formation (Missour- ranges in age from early Des Moinesian to early Wolfcampian. ian, Virgilian, and Wolfcampian), and the Bursum Formation (Wolf- campian). Los Moyos Limestone SANDIA FORMATION The Los Moyos Limestone is about 180 m thick, and it forms the The Sandia Formation is a slope-forming sequence of olive-drab prominent white cliffs along the crest of the mountains between Capilla micaceous siltstone, sandstone, and conglomerate; it also contains a Peak and Guadalupe Peak. The contact of the Los Moyos and the few discontinuous thin beds of marine limestone. The Sandia lies on underlying Sandia Formation is gradational; the base of the Los Moyos Precambrian rocks except at Bosque Peak and at the southern side of was mapped at the base of the lowermost ledge-forming, cherty lime- Tijeras Canyon where less than 4 m of Mississippian limestone be- stone. These lower beds, a total of more than 60 m thick, are medium- longing to the Arroyo Pefiasco Group intervenes locally. The average gray calcarenite that contains lenses and bands of rusty weathering, thickness of the Sandia is about 61 m; however, the thickness ranges dark-gray chert and minor amounts of interbedded calcareous shale. from less than 15 m to about 92 m. The differences in thickness are The chert, characteristically a rusty-orange color on weathered surfaces, the results of pre-Sandia erosional relief on the Precambrian. is typical of the lower beds of the Los Moyos. At most localities the basal beds of the Sandia are conglomerate or Above the cherty limestone is a 1-to-3-m thick zone of conglomerate, coarse-grained sandstone, derived from nearby Precambrian rocks. The sandtone, siltstone, and, locally, silty calcarenite that is persistent basal beds are overlain by olive-drab sandstone, siltstone, and shale throughout the mountains. At some places, rocks of this zone contain that contains fossil wood and plant impressions; thin beds of carbon- silicified logs as long as 2.5 m; at other places, in the northern part of aceous shale and lenticular beds of coaly shale are present locally. the mountains, there are lenticular beds of limestone conglomerate Lenticular beds of impure silty limestone that contain the fusulinid whose cobbles are well-rounded and have algal coatings as much as Fusulinella and a few brachiopods are present. 6.5 mm thick. The matrix of the limestone conglomerate contains Overlying these basal beds is a medial sequence of micaceous, olive- debris of abraded brachiopods, crinoid-stem segments, and other marine gray to yellowish-brown sandstone and siltstone that contains a few fossils which also have algal coatings; some of the clasts contain thin, lenticular beds of gray calcarenite. Dark-gray to brownish-gray Komia sp. carbonaceous shale, locally gypsiferous, occurs at some places. Plant The remainder of the Los Moyos above the sandstone-conglomerate impressions are common. At the top of these medial beds is a persistent zone is medium-gray, cliff-forming, cherty calcarenite that changes zone of calcareous sandstone that contains casts and molds of brachio- upward into light-olive-gray calcarenite. Local beds of sandstone, con- pods, crinoid-stem segments, clams, and other marine fossils. glomeratic sandstone, siltstone, and calcareous shale are interbedded The upper beds of the Sandia, a total of about 21 m thick, are with the limestone and become more common toward the top. transitional upward from dominantly terriginous deposition to domi- The fusulinids Beedeina arizonensis, Fusulinella famula, and prim- nantly marine deposition. In these beds, there is a gradual upward itive species of Wedekindellina are found in the basal beds of the Los increase in the proportion of shale versus sandstone and siltstone, and Moyos. These fusulinids are succeeded upward by an assemblage dom- a concurrent increase in the amount of calcareous material. Marine inated by Beedeina novamexicana. The upper beds contain Beedeina fossils are common in the upper 9-12 m; chert is an important constituent sulphurensis and related species. Locally, in the uppermost beds of the 236 MYERS Los Moyos, Eowaeringella joyitaensis has been found. The fusulinids than 30 m thick. The basal unit is overlain by thinly-bedded yellow to indicate that most of the Los Moyos is of Des Moinesian age, and that gray siltstone and calcareous shale. the uppermost beds are, at least locally, of early Missourian age. The uppermost part of the Pine Shadow Member is ledge- or cliff- forming. Near Sol se Mete, the upper beds are 15 m of calcarenite; in Wild Cow Formation the Tajique area, there are 3 beds of calcarenite separated by sandstone The Wild Cow Formation, defined by Myers (1973), consists of and calcareous shale; at the type section, 2 beds of limestone are sep- arated by siltstone. The limestone is mostly light-olive gray calcarenite alternating sequences of arkosic sandstone, sandstone, conglomerate, that is locally cherty. It is generally from 15 to 21 m thick but may be gray to yellow siltstone and shale, gray to black calcareous shale, and as much as 40 m thick. thin- to thick-bedded calcarenite that is locally cherty. Some of the Algal colonies about the size and shape of golf balls weather into limestone in the upper part of the formation contains angular megascopic relief and are prominent at the top of the upper limestone beds in the fragments of detrital pink feldspar.

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