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Paleozoic Evolution of Southern Margin of Permian Basin

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Paleozoic Evolution of Southern Margin of Permian Basin Paleozoic evolution of southern margin of Permian basin CHARLES A. ROSS Chevron U.S.A., Inc., P.O. Box 1635, Houston, Texas 77251 ABSTRACT a relatively stable tectonic area. The Glass those of the Marathon basin (Wilson, 1954b). Mountains expose a series of north- and Faulted and folded sandstone turbidite beds Prior to Late Pennsylvania!! time, the northwest-dipping cuestas of Permian car- identified as the Tesnus Formation (Mississip- Permian basin o f West Texas was a part of bonate shelf and shelf-edge deposits that pian) are also exposed. The stratigraphi; units the southern margin of the North American accumulated on a platform constructed from are the same as those known from the Marathon craton and was the site of shallow, warm- these two allochthonous accretionary basin, and so the Solitario exposes a south- water carbonate deposition. As the South wedges. These Permian deposits prograded south westward continuation of the Marathon American margin of Gondwana gradually north and northwestward into the narrow fold belt. Small patches of Cambrian, Ordovi- moved northwestward during late Paleozoic Hovey Channel, which connected the Marfa cian, and/or Tesnus beds are also exposed be- time, the oceanic floor deposits and overlying basin with the southern end of the Delaware neath Lower Cretaceous beds at the Olc. Jones turbidite fan deposits between North America basin. Carbonate-reef growth finally re- Ranch, southeast of the Marathon basin, and at and South America became parts of large ac- stricted the inflow of marine water into the Persimmon Gap, near the entrance to Big Bend cretionary wedges of semiconsolidated sedi- Delaware basin near the end of late Guadalu- National Park (Fig. 1). ments. In a series of steps, these wedges were pian time. Until the late 1960s and early 1970s, the re- folded and thiust toward the northwest gion west of these erosional windows was against, then fuuilly onto, the southern margin INTRODUCTION poorly understood, and, even at present, only a of North America. These compressive steps general outline seems possible. This region of caused the repeated piling up of the accre- This paper reviews the Paleozoic strata along >8,000 mi2 (25,000 km2) includes the Marfa tionary wedges to form rapidly eroding high- the southern margin of the Permian basin and basin, Hovey Channel, and the southern end of lands on the cratonic margins. Repeated their depositional histories and the tectonic the Diablo Platform (Fig. 3) and is covered by loading on the North American margin events that formed and then closed the southern extensive deposits of Cretaceous and Cenozoic formed a series of elongate, deep-water, dep- end of the Permian basin. The southern margin age. Most of our present understanding of the ositional troughs (fore-deeps) immediately of the Permian basin is almost completely cov- Paleozoic history of this region is based on data north and west of the accretionary wedges, ered by Mesozoic and Cenozoic rocks, except from ~20 deep drill holes and on several small and these received thick accumulations of for two large erosional windows and several exposures of late Paleozoic rocks in the Chinati turbidites. The youngest of these deep basins smaller ones that give us incomplete views (Fig. Mountains (Fig. 1), —50 mi (80 km) west of the include the northwestern part of the Val 1). The largest window is made up of two dis- Marathon basin. These Paleozoic outcrops in- Verde basin to the north and the Marfa basin tinct parts, the Marathon basin and, adjacent to clude thick successions of basinal shale, siltstone, to the west which received basinal deposits it on the north, the Glass Mountains. The other and sandstone turbidites and only minor shal- from within Desmoinesian into early Late large window is the Solitario, a dome ~50 mi low-water units. Permian time. (80 km) to the south-southwest. North of the Glass Mountains, considerably Loading of the cratonic margin also re- The Marathon basin exposes complexly more deep drill-hole data are available. The sulted in renewed faulting along generally folded and faulted strata, most of which were Permian shelf carbonates in the Glass Mountains northwest- to north-trending older zones of deposited in deep-water environments (Fig. 2). were deposited on imbricated thrust sheets, the weakness. These zones are apparently of These strata were deformed and thrust north- youngest of which is middle Wolfcarr.pian in Precambrian a^e. On the craton, the late Pa- westward as allochthonic masses in front of an age, and are composed of basinal turbidites and leozoic faults mainly had high-angle to verti- advancing cratonic mass that came from the clastics. These have been thrust on top of Late cal fault planes and commonly had large southeast (King, 1930b, 1937). In contrast, the Pennsylvanian-early Wolfcampian basinal de- components of horizontal displacement. This Glass Mountains are composed of a succession posits that overlie a cratonic succession made up fault system outlines the major uplifts and of chiefly carbonate strata that form northwest- of carbonate-shelf facies of Middle Pennsylva- basins in the Pe rmian basin region. dipping cuestas (Fig. 2). In comparison to the nian and older beds. The northern limit of these The joining together of Gondwana and Marathon basin, strata in the Glass Mountains thrusts formed the southern edge of the Permian Euramerica across the Marathon salient of are relatively undisturbed and, for the most part, basin, which approximately corresponds to the the orogenic bel t was essentially completed by were deposited as shallow-water shelf or shelf- northern exposures of Permian rocks, in the mid-Wolfcampian time. After that time, the edge beds. Glass Mountains (Moore and others. 1981). southern margiin of the Permian basin, rep- The Solitario (Fig. 1) exposes a much smaller Northwest of the Glass Mountains, the Hovey resented by the Dugout and Marathon area. There, lower Paleozoic strata are com- Channel (Fig. 3) lay between rocks of i;he mid- allochthons and the Diablo Platform, became plexly folded and faulted in the same manner as dle Wolfcampian allochthon and the cratonic Geological Society of America Bulletin, v. 97, p. 536-554, 10 figs., May 1986. 536 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/97/5/536/3419496/i0016-7606-97-5-536.pdf by guest on 25 September 2021 PALEOZOIC EVOLUTION OF PERMIAN BASIN 537 • FT. \VAN HORN MTNS STOCKTON SIERRA SOUTHERN SHELF O FACIES MADERA DIABLO SHELF FACIES I;-': \| MARFA BASIN FACIES MARFA • P^j DUGOUT ALLOCHTHON DUGOUT CREEK FAU LT t N3 MARATHON \ J ALLOCHTHON HOUSE TOP MTN JÄ^PINTO CA RUIDOSA CIBOL8 O CREEK \ (h OLD JONES CHINATI MTNS \ RANCH 1 "àj^MSHAFTER CHa, vy HELLS HALF ACRE - ~<^Df>a,a ^0/ DEVILS BACKBONE FAU LT Figure 1. Location of Paleo- f^^i^^y /0/1" GAP / zoic outcrops in Marathon ba- sin, Glass Mountains, Chinati Mountains, and Van Horn Mountains areas in West Texas. Diablo Platform. Northeast of the Glass Moun- tain, another channel, the Sheffield Channel, separated the cratonic Central basin Platform from the middle Wolfcampian allochthon. PREVIOUS INVESTIGATIONS Many geologists have contributed signifi- cantly to a better understanding of different as- pects of the complex geology of the region. major diastrophism in the Marathon orogenic the region were made. Thomson and Thomas- Many interpretations have been diametrically belt, a problem that continued to hold his inter- son (1964) interpreted the Pennsylvanian Dim- opposed, and these have stimulated lively de- est after retirement, because he wrote me in the ple Limestone as including both shelf and bate. A broad, general understanding of the mid-1960s pleased to have read evidence that turbidite carbonates. McBride (1964, 1966) Glass Mountains-Marathon basin region, how- pieced together at least two major diastrophisms studied the flysch sedimentology of the Pennsyl- ever, does exist and forms the basis for this (Ross, 1963a). Among the most valuable studies vanian Haymond Formation. Ross (1959, discussion. of this era were those of King (1930b, 1937), 1963a) restudied the Permian Wolfcampian Se- Early studies of the geology of the Glass who carefully mapped the Glass Mountains and ries and showed that the last major thrusting Mountains-Marathon basin area and adjacent most of the Marathon basin on a scale of event was within the middle of that epoch. Ross areas started at about the beginning of this cen- 1:62,500 and placed this succession of complex (1967) showed that the shelf facies of the Penn- tury with Hill's (1901) Physical geology of the strata into a stratigraphic and structural frame- sylvanian Gaptank Formation in the northern Texas region. Udden (1907, 1917), Baker and work that others could use. part of the Marathon basin was deposited on a Bowman (1917), and Bôse (1917) made impor- Faunal studies on ammonoids by Smith thrust sheet that included strata as young as late tant early contributions. In the late 1920s, a (1929) and Miller and Furnish (1940), on Desmoinesian. Extensive brachiopod studies by number of geologists looked at various parts of brachiopods and other faunas by R. E. King Cooper and Grant (1972-1977) made the the Marathon basin, the Glass Mountains, and (1932), and on fusulinids by Dunbar and famous Permian silicified faunas of the Glass the Marfa basin and recognized both the impor- Skinner (1937) did much to establish the Glass Mountains much better known. tance and the difficulties of interpreting the re- Mountains as a stratigraphic reference section More recently, interest in the Glass Moun- gion. Schuchert (1927) tried to place the area for the Lower and lower Upper Permian, not tains-Marathon basin and other southern areas into a regional perspective, and King (1930a; only in southwestern North America but world- of Paleozoic exposures has centered on two im- King and King, 1928, 1929) summarized their wide (Adams and others, 1939).
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