Controls on Early Cretaceous Carbonate Platform Margin Development: Northeastern Gulf of Mexico

William Corso, Richard T. Buffler, James A. Austin, Jr.

A seismic stratigraphic analysis of approximately 3,000 km of multifold reflection data correlated to available geologic information documents the development of an Early Cretaceous carbonate platform margin in the De Soto Canyon area of the northeastern Gulf of Mexico. During the Jurassic(?), inferred oceanic and thin transitional crust underlying the Gulf subsided and formed a flexure zone on which the Early Cretaceous margin developed. By the late Aptian to late Albian, two types of margin morphologies evolved in response to different paleogeographic settings. Northwest of De Soto Canyon, a gently dipping "accretionary" slope morphology formed as a result of its proximity to a terrigenous clastic province. Seawater turbidity and chemistry probably inhibited buildup for ation on this leeward margin, thus allowing both carbonate and siliciclastic sediments to be transported from the platform interior to the adjacent slope. Southeast of De Soto Canyon, the carbonate province was "cleaner" and a steeply dipping "bypass" slope morphology formed due to the development of robust buildups that probably limited downslope deposition of platform-derived sediments, thereby gradually starving the adjacent basin.

Total tectonic subsidence profiles across both types of margin morphologies show steeper gradients associated with the "bypass" slope morphology, suggesting that differential subsidence rates contributed to the development of the margin's morphology and may reflect the margin's proximity to the oceanic-continental crust boundary.

In the late Albian, the platform interior drowned in response to a pronounced fluctuation in short-term eustatic sea level superimposed on a long-term rise. Buildups continued to form at the margin, however, until they drowned in the middle Cenomanian due to another big change in short-term eustatic sea level combined with down-to-basin faulting and the continuing long-term rise.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.