BUFFLER, RICHARD T., University of Texas Institute for Geophysics, Austin, TX; DAVID A. DEBALKO, Arco Oil and Gas, Houston, TX; and LAURA M. DOBSON, Exxon Exploration Company, Houston, TX

ABSTRACT: Mesozoic Seismic Stratigraphy and Geologic History, Northeast Gulf of Mexico

The crustal structure and basin configuration of the northeast Gulf of Mexico, as outlined by a contour map on the prominent mid-Jurassic (sub-salt) surface (MJS), influenced the distribution and development of the overlying Middle Jurassic through Lower Cretaceous sequences. The Louann salt, deposited during or just after crustal attenuation, is thick in basinal areas and thin or absent over adjacent highs. During Smackover time a broad shelf to prograding ramp partially filled the basinal areas, while scattered carbonate buildups developed along surrounding highs. Shelf margins continued to prograde basinward during Haynesville time, almost filling the Tampa embayment and culminating in a steep starved carbonate margin in the western Apalachicola basin. Cotton Valley time (latest Ju assic) is characterized by a broad, dominantly clastic, prograding ramp that filled the basins and overlapped the highs, while deep-sea fan systems developed in the adjacent deeper basin.

During the Lower Cretaceous a rimmed carbonate margin developed along a tectonic hinge zone at the boundary between thick and thin transitional crust. Siliciclastic sediments may have bypassed the Lower Cretaceous carbonate margins during sea level lowstands and formed potential reservoir rocks within deep-sea fan systems. As the margins continued to aggrade and steepen, currents intensified along their base, altering depositional patterns and processes, culminating in the widespread mid-Cretaceous sequence boundary (MCSB). Mid-Cretaceous long-term rise in sea level superimposed on short-term rises and falls and changing environmental conditions terminally drowned the margin and caused retreat to more landward positions.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.