Geological Circulars

Permanent URI for this collectionhttps://hdl.handle.net/2152/121888

Peer-reviewed geoscience research summaries, targeted on Bureau project areas in Texas and other locations, 1965–2003.

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Geology and geohydrology of the East Texas basin: a report on the progress of nuclear waste isolation feasibility studies (1979)
(University of Texas at Austin. Bureau of Economic Geology, 1980) Kreitler, Charles W.; Agagu, Olusegun Kokumo, 1948-; Basciano, Joyce M.; Collins, Edward W.
Analysis during the second year was highlighted by a historical characterization of East Texas Basin infilling, the development of a model to explain the growth history of the domes, the continued studies of the Quaternary in East Texas, and a better understanding of the near-dome and regional hydrology of the basin. Each advancement represents a part of the larger integrated program addressing the critical problems of geologic and hydrologic stabilities of salt domes in the East Texas Basin. During the second year of the East Texas salt dome studies, significant advances in understanding the hydrologic and geologic stabilities of salt domes were based on the acquisition of much new data. Among these new sources of data are (1) 400 km (250 mi) of seismic reflection data that are both regional and site specific, (2) gravity data for the East Texas Basin, (3) 20 shallow boreholes over Oakwood Dome, (4) 1 hydrologic test hole downdip from Oakwood Dome, and (5) a complete core of the anhydrite-gypsum cap rock over Gyp Hill Dome in South Texas. The acquisition of seismic, gravity, and electric log data provided new understanding of the sedimentary infilling of the East Texas Basin and how it caused salt migration and dome growth. Deposition of the Travis Peak-Schuler sediments caused the first differential loading of the underlying Louann Salt and the migration of the salt into anticlinal ridges. Subsequent clastic depocenters occurred laterally to Travis Peak depocenters and caused further migration of the salt into diapirs. The greater the sediment loading, the further the salt anticline advanced through Trusheim's (1960) growth sequence: pillow structure to immature diapir and finally to a mature diapir. Most domes in the basin can be placed within this dome growth sequence. Analysis of the Gyp Hill cap rock showed that the cap rock was the result of salt dome dissolution and the accumulation of the insoluble residuum, anhydrite. Work completed on the Carrizo-Wilcox aquifer, the major fresh-water aquifer in the basin, shows that this aquifer has the greatest potential for causing dome dissolution leading to radionuclide transport. Ground-water circulation is controlled primarily by topography and structure. Fluid movement is generally downward because of the structural dip and leakage from overlying units. Chemical composition of the water evolves from a low-pH, oxidizing, calcium bicarbonate water in the outcrop to a high-pH, reducing, sodium bicarbonate water deeper in the aquifer. This chemical change has important implications for radionuclide transport.
Quaternary faulting in East Texas
(University of Texas at Austin. Bureau of Economic Geology, 1980) Collins, Edward W.; Kreitler, Charles W.; Hobday, David K.
Three closely spaced oblique-slip faults displace a Quaternary gravel and sand unit overlying Eocene Claiborne strata in the Trinity River Valley, Leon County. These steeply dipping faults strike east-northeast; two of them are downthrown toward the south, with a smaller, antithetic, central fault downthrown to the north. Maximum slip on individual faults is 118 cm (46.5 inches), decreasing to 66 cm (26 inches) where these faults displace the overlying Quaternary gravels. The location and trend of these faults are consistent with the configuration of the Mt. Enterprise-Elkhart Graben system; this relationship is verified by subsurface data and aerial photograph lineaments. The precise age of the Quaternary unit involved is uncertain. It is tentatively correlated with deposits of the Wisconsin interstadial 37,000 B.P., implying late Pleistocene or Holocene reactivation of the fault system. Mechanisms responsible for the fault may have involved fluid extraction in Long Lake Oil Field to the north, salt movement, or load-induced crustal warping. Coincidence of a belt of seismic activity with the fault trend suggests that faulting was probably related to hinge line effects between the East Texas Basin and the currently active Gulf Basin.
Styles of deformation in Permian strata, Texas Panhandle
(University of Texas at Austin. Bureau of Economic Geology, 1984) Collins, Edward W.
Permian strata in the Texas Panhandle exhibit a variety of deformation styles that are attributed to tectonic stresses as well as to collapse caused by evaporite dissolution. At Caprock Canyons State Park, deformation structures above salt dissolution zones include veins, faults, and folds. The geometry and distribution of the structures indicate that systematic regional joints older than the dissolution collapse have influenced salt dissolution. At Palo Duro Canyon State Park, subparallel cylindrical folds and minor reverse faults indicate east-northeast and west-northwest (075°to 255°) compression related to regional folding. Evaporite dissolution and subsequent collapse of strata have also deformed Permian strata and developed closed synclinal depressions, faults, and veins. Along the Canadian River valley in Potter County, Permian and Triassic strata are folded over fault-bounded basement highs as the result of either differential compaction or recurrent motion on basement faults. Synclinal depressions, clastic plugs, and clastic dikes caused by dissolution-induced collapse processes also occur throughout this area.
The queen city formation in the east Texas embayment: a depositional record of riverine, tidal and wave interaction
(University of Texas at Austin. Bureau of Economic Geology, 1980) Hobday, David K.; Morton, Robert A.; Collins, Edward W.
Five distinct facies are recognized in the Eocene Queen City exposures between the Trinity River valley and the Louisiana state boundary. These facies (fluvial, deltaic, tidal flat, barrier, and tidal delta) display diagnostic suites of physical and biogenic structures. Sandstones within these facies exhibit substantial differences in paleocurrent pattern. Fluvial influx was mainly from the northwest, with subordinate contributions of sediment from the east. A margnal alluvial and upper deltaic plain was transected by fluvial channels of fluctuating bedload to suspended load proportions and variable preservtion potential. Along the northwestern embayment margin, small, high-constructive shoal water deltas and crevasse subdeltas developed and prograded across the shallow Reklaw shelf. Barriers may have originated as destructive components of delta abandonment or as contemporaneous strike-fed features marginal to the main delta complex to the west. In either event, barriers are poorly preserved, possibly because of transgressive ravinement, but more likely because they were never developed on a major scale. Extensive backbarrier or bay-margin intertidal and subtidal flats and shoals reflect the interplay of tidal and wave-generated processes, leaving a characteristic record of variable physical energy and flow patterns. Flood-tidal deltas formed at the mouths of microtidal estuaries and, like some modern analogues, they were significantly larger than comparable mesotidal features. The inferred flood-tidal delta deposits also exhibit features reflecting storm processes. Regional depositional patterns were largely controlled by: 1) location of the east Texas embayment with respect to the major deltaic depocenter, resulting in an eastward decrease in sediment supply; 2) configuration of the broadly funnel-shaped embayment and wide shelf, which may have augmented tidal range; and 3) transition from overall progradational character, with local transgressions, to a major marine transgression that culminated in shelf sedimentation of the overlying Weches Formation.

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Browsing Geological Circulars by Author "Collins, Edward W."