Salt tectonics and seismic stratigraphy of the Keathley Canyon Area and vicinity, northwestern Gulf of Mexico /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The continental slope of the northwestern Gulf of Mexico is a region of high degree geologic complexity due to deformation and movement of underlying salt. Analysis of over 7,500 km of multichannel seismic data from the Keathley Canyon Area and vicinity contributes to an understanding of the structure and stratigraphy of this area. Salt in the northeastern part of the study area and adjacent updip regions originated from a deep mid-Jurassic salt layer. A NW-SE structural trend of salt in these areas may reflect basement influence. As the salt rose to shallower depths, the downslope part of the salt moved seaward as allochthonous tongues that evolved into ridges and massifs. Progradational differential loading of the Cenozoic sediments on the shelf and upper slope is believed to be the primary mechanism for the seaward migration of salt. Intraslope basins formed locally by withdrawal of the salt. Lobes of salt spreading seaward formed the Sigsbee Escarpment along the base of the slope. The NW-SE trending ridges and basins superposed on allochthonous salt may have been influenced by the NW-SE trending salt features in the updip regions. Potential hydrocarbon traps were created both below and above the salt layer. Keathley and Bryant canyons indent the Sigsbee Escarpment salt front. Keathley Canyon appears to have been formed by salt tectonism. Beneath the upper Keathley Canyon, laterally moving salt lobes uplifted continental slope and rise sediments. These coalesced and resulted in a valley-like feature with walls of uplifted and deformed strata. Erosion of canyon-wall sediments may have preserved or steepened the upper canyon. Downslope, a broad interlobal bathymetric low forms the lower Keathley Canyon. In contrast, Bryant Canyon appears to be an erosional feature that was part of an old Mississippi River-canyon-fan system. Bryant Canyon involves several intraslope basins and well-developed valleys. In interbasinal areas where Bryant Canyon apparently cuts shallow salt masses, the canyon has little seafloor expression probably due to intensive salt tectonism. Seismic stratigraphic interpretation suggests that sea-level cycles were a major factor in the depositional patterns of the area. As sea level fell, sediments from the shelf and upper slope were transported downslope. Most sediments were deposited as slope fans within subsiding salt-withdrawal basins. During sea-level lowstands, shallow-water sediments prograded onto the slope filling salt-withdrawal basins with turbidites. During sea-level rises and highstands, most sediments were deposited on the shelf and upper slope and sediment-starved condensed sections formed on the lower slope and deeper water regions. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Oceanography." |
| Physical Description: | xvi, 182 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |