Cross Sections

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    Regional stratigraphic cross sections, Comanche cretaceous (Fredericksburg-Washita division), Edwards and Stockton plateaus, West Texas : interpretation of sedimentary facies, depositional cycles, and tectonics
    (University of Texas at Austin. Bureau of Economic Geology, 2000) Smith, Charles Isaac, 1931-
    Six interlocking regional stratigraphic cross sections of Lower Cretaceous strata (middle Albian-lower Cenomanian) of the Edwards and Stockton Plateaus of West Texas illustrate the vertical and lateral extent of lithostratigraphic units and distribution of facies and facies tracts. Facies maps, prepared along selected horizons and thought to represent a brief period of time, and maps illustrating features along critical stratigraphic boundaries are interpreted to illustrate paleoenvironmental distributions through time, as well as stratigraphic relationships. The interval from the top of the Trinity division (cop of the Glen Rose Formation) to the top of the Comanchean Series is considered to be a natural, physically defined stratigraphic division, the Fredericksburg~Washita, containing three subdivisions that define the regional stratigraphic framework. Three and one-half depositional cycles are identified within the lower-middle subdivisions and interpreted in terms of sedimenta- tion, tectonics, and eustasy. The base of the division may be interpreted as a tectonically enhanced type-2 sequence boundary, whereas three other possible boundaries (one in the lower and two in the middle subdivision) would be considered transitional sequence boundaries if they are related to eustatic cycles.
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    Regional structural cross-sections, Mid-Permian to Quaternary strata, Texas Panhandle and eastern New Mexico; Mapping of Quaternary of Rolling Plains
    (University of Texas at Austin. Bureau of Economic Geology, 1988) McGookey, Douglas A.
    The Palo Duro Basin of the Texas Panhandle and eastern New Mexico contains bedded Permian salts of sufficient thickness and depth for the basin to be considered as a potential site for long-term storage and isolation of high-level nuclear waste. Salt (primarily halite) is a desirable host rock because of its low permeability, high thermal conductivity, low moisture content, and high gamma-ray shielding properties (Johnson, 1976b). A major concern that was addressed during the waste isolation study of the Texas Panhandle region is the long-term integrity of the bedded-salt host rock. Areas where salt has been removed by dissolution have been identified beneath the Southern High Plains, along the eastern and western escarpments of the Southern High Plains, and along the Canadian River valley (Gustavson and others, 1980b; Presley, 1980a, 1980b; Gustavson and Finley, 1985; Gustavson, 1986). Regional cross sections of mid-Permian to Quaternary strata in the Texas Panhandle and east- ern New Mexico illustrate lithologic and structural relations that are interpreted to have resulted from the regional dissolution of salt and the collapse of overlying strata. The cross sections were constructed using gamma-ray logs, sample logs, and surface geologic maps (Handford, 1980a; McGillis, 1980). Gamma-ray logs are shown on the cross sections because they best demonstrate variations in evap- orite strata. Figure 1 is an index map depicting the locations of the cross sections. Stratigraphic nomen- clature used on the cross sections is given in table 1.
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    Regional stratigraphic cross sections, Upper Pennsylvanian and Lower Permian strata (Virgilian and Wolfcampian Series), north-central Texas
    (University of Texas at Austin. Bureau of Economic Geology, 1987) Brown, L. F. (Leonard Franklin), 1928-
    A regional network of 14 dip (E-W) and 9 strike {N-S) stratigraphic cross sections correlates upper Pennsylvanian (Virgilian) and lower Permian (Wolfcampian) strata throughout the subsurface in all or parts of 28 counties of North-Central Texas. The network covers 22,000 mi (57,000 km) and was constructed by combining outcrop data with electric log data from 1,185 weils along 2,000 mi (3.200 km) of cross sections to correlate about 20 limestone units. The network was further verified by correlating the limestones on electric logs from 4,000 additional off-section wells for a total of more than 5,100 control points. Cores and samples were used locally to calibrate the lithic interpretation of electric logs. The cross sections are published with a horizontal scale of approximately 6 mi/inch (4.2 km/cm) and a vertical scale of 200 ft/inch (26.6 m/cm). Regionally persistent limestone units (1) provide a reliable subsurface correlation network, (2) comprise a stratigraphic framework for facies mapping, (3) equate outcrop type sections with subsurface equivalents, (4) document major vertical and lateral variations within principal lithogenetic sequences, and (5) permit integration of a variety of subsurface and surface geologic data. The cross sections define 16 principal and several lesser lithogenetic units, each composed of cyclic coastal onlap limestone sequences and progradational/aggradational terrigenous clastic sequences. The progradational/aggradational clastic sequences are composed of platform fluvial, fan-deltaic, deltaic, and interdeltaic systems and shelf-margin deltaic, interdeitaic, slope, and basinal sequences, as well as some local contemporaneous shelf and shelf-edge limestone systems. Coastal onlap limestone sequences contain principaily transgressive, aggradational, and progradational limestone facies and thin, discontinuous, basal transgressive sandstone and shale facies deposited within nearshore, shelf, shelf-edge, and slope systems. The cyclic sequences were controiled by variations in relative sea level resulting from an interplay between variable rates of tectonic subsi- dence and tilting, compaction subsidence, sediment supply, and eustatic sea-level variations. Deposi- tional sequences were correlated westward from outcrop, across the Eastern Shelf, over shelf edges, and down the slope to pinch out on the floor of the Midtand Basin. Many tectonic and paleobathymetric elements are clearly delineated: the northern terminus of the Fort Chadbourne Fault Zone
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    Regional cross sections-- Central Basin Platform, West Texas
    (University of Texas at Austin. Bureau of Economic Geology, 1985) Bebout, Don G.
    In 1982, the Bureau of Economic Geology initiated a project to characterize the major oil fields of Texas. The project led to the compilation of an atlas summarizing the general geologic setting and production statistics of all fields that have produced more than 10 million barrels of oil (Galloway and others, 1983). During this compilation, the need arose for regional stratigraphic control for the various large fields on the Central Basin Platform, and these cross sections were constructed to fill this need. Well logs (mostly gamma ray/neutron, but also electrical and sonic} from wells spaced approxi- mately 5 mi apart are included on the 11 cross sections. Only the deepest wells are used, and most reach the Ellenburger Formation. Wherever possible the sections are directed through the major oil fields, those that have produced more than 10 million barrels of oil, and logs from those fields are included on the sections. The zone or zones of production are indicated on the well representing each field. Correlations of the entire Paleozoic section (fig. 1) were obtained from other published cross sections (West Texas Geological Society, 1962, 1964), cross sections and paleontological data from proprietary company files, compilations of oil-field studies (Herald, 1957; Stipp, 1960; West Texas Geological Society, 1966, 1969), and the records of the University Lands Office, Midland, and Railroad Commission of Texas, Austin. Where deep wells were not available a tectonic map of Texas (Ewing, in preparation) was used to aid in placing the tap of the Ellenburger Formation. Many disconformities are recognized in the Paleozoic section of the Central Basin Platform. However, only the regional! unconformity at the base of the Wolfcampian Series, where the rocks of entire geologic systems are missing, is indicated on the sections. Major faults are shown on the cross sections, and they are all indicated to be vertical because of lack of detailed data on the dip of the fault planes. The locations of the faults were obtained from the sources cited above or were recognized through identification of abrupt changes in elevation of markers from one weil to the next; the faults shown on the sections correspond to the major faults on the tectonic map compiled by Ewing (in preparation). These regional cross sections are intended to be used for preliminary correlation or to obtain an introduction to the geology of the Central Basin Platform area (fig. 2). For detailed information ona local area, reference shouid be made to the sources of field studies cited above.