Abstract: Time-Structure Map of Shelf and Slope, Rio Grande River to Northwest Florida, Gulf of Mexico

Joel S. Watkins, William R. Bryant, Jiebo Xi, Fangjian Xue

We have mapped the seismic structure of the Neogene and, where resolved on seismic, earlier levels in the northern Gulf of Mexico from the Rio Grande River in South Texas to DeSoto Canyon Salt basin offshore northwestern Florida.

The map presented here is a montage of two Miocene horizons and one Plio-Pleistocene horizon over the Texas-Louisiana shelf, top of Smackover in the MAFLA and eastern Mississippi delta regions and top of salt over the slope. Complex structure and lack of deep paleo control limits depth of Neogene mapping to 3-4 sec (12,000-15,000 ft). Simpler structure and deeper paleo control in the MAFLA region permit mapping to depths of 30,000 ft or more. Depths to top of salt over the slope are relative to the seafloor; that is, the map indicates the time-thickness of sediments above the salt. Maximum resolvable depths were =>15,000 ft. Our data rarely resolved base of salt in the Texas-Louisiana slope.

The mapping is based on a >80,000 mi grid of seismic data. Grid spacing over the shelf is = <4 mi for the most part. Locally the grid may be as close as 2 mi, or as wide at 6 mi in a few areas where structure is uncomplicated. Slope line spacing is generally <10 mi but locally may be as much as 20 mi. Paleo tops from over 700 wells and well logs from about the same number of wells provided temporal and lithologic control.

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