Abstract: Regional Structure and Stratigraphy of the Texas Shelf, Gulf of Mexico

Sik Huh, Joel S. Watkins, Barry E. Bradshaw, Jiebo Xi, Robert Kasande

Miocene sediments cover most of the Texas shelf. Four long, relatively straight growth faults dominate the Miocene structure. These are, in order of decreasing age, the Early Miocene Lunker, the Early Miocene Clemente-Tomas, the Middle Miocene Corsair and the Late Miocene Wanda faults. The Lunker and Clemente-Tomas detach into high, linear shale ridges formed from overpressured prodelta muds. The Corsair and Wanda faults detach into a salt sheet, now largely evacuated. Uplift of the Clemente-Tomas ridge triggered formation of the Corsair and uplift of Corsair-loaded salt triggered formation of the Wanda fault. A single detachment may be common to all four faults.

Structural and stratigraphic variations suggest that the region is underlain by of three NW-SE trending rift-stage corridors separated by transfer faults. For example, growth faults trend NNE in the southern South Perdido corridor, they trend NE in the central North Perdido corridor, then bend Eastward and diffuse into a confusing anastomosing fault pattern similar to patterns offshore Louisiana in the eastern Brazos-Sabine corridor.

Salt diapirs are rare in the Miocene section except for a prominent zone in the Galveston South Addition.

Plio-Pleistocene sediments fill a triangular wedge that widens northward from the southwest corner of Galveston South Addition. At its greatest N-S extent along the Louisiana border, the wedge extends from the shelf-edge into the lower part of High Island East Addition. Main Plio-Pleistocene faults trend Eastward in contrast to the NE trend of most Miocene faults.

Deposition mirrors structure. Hangingwall heave created accommodation space seaward of major growth faults. Deposition into this space resulted in a string of elongated bead-like depocenters immediately seaward of major growth faults. A prominent slump is evident in the High Island South Addition Plio-Pleistocene section.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas