--> ABSTRACT: Subsidence and Thermal Histories of Northeast Gulf of Mexico, by B. W. Driskill and J. A. Nunn; #91030 (2010)

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Subsidence and Thermal Histories of Northeast Gulf of Mexico

B. W. Driskill, J. A. Nunn

Subsidence and thermal histories of southern Mississippi and Alabama, and the panhandle of Florida were modeled. An extensive grid of north-south and east-west cross sections, based on deep well data, provided input for backstripping. Tectonic subsidence curves obtained from backstripped sediment columns accurately fit simple curves similar in shape to thermal decay curves. Comparison of tectonic subsidence curves with theoretical uniform extension curves shows this area experienced a period of extension and has since passively subsided owing to lithospheric cooling. The amount of stretching increases from a minimum at the peripheral fault zone to higher values toward both the Mississippi salt basin and the Gulf of Mexico. Results also indicate that subsidence in the nort east Gulf of Mexico began during the Late Jurassic. Other studies concerning the northwest Gulf Coast suggest that subsidence began at an earlier time. This difference could be due to either a west-to-east propagating rift system in the Gulf of Mexico or, in the northeast, nonuniform stretching that caused initial uplift. The thermal state of the sediment fill was modeled through time, using the one-dimensional heat flow equation. Controls for the model include both bottom-hole temperatures and observed percent Ro. The Jurassic Smackover Formation, which is the regional source rock, entered the oil window during the Early Cretaceous. Smackover maturity roughly follows production trends across the study area, with higher maturities found in deeper, basinward areas. In contrast o the deeper Gulf, where overpressuring and thick Tertiary deposits are factors in predicting petroleum generation, the main control on the thermal maturity of sediments in the northeast Gulf Coast is simple basin subsidence caused by lithospheric extension.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.