Characterization of Paleocene-Eocene depositional sequences in the eastern Gulf Coastal Plain of Mississippi and Alabama, involving outcrop study integrated with well log analysis, resulted in the recognition of six Upper Paleocene and Lower–Middle Eocene third-order unconformitybounded depositional sequences. These sequences include the Naheola Formation (Midway Group) , the Nanafalia , Tuscahoma, and Hatchetigbee formations (Wilcox Group), and the Tallahatta Formation (Claiborne Group).

The Paleogene depositional history of the eastern Gulf Coastal Plain was dominated by fluvial-deltaic, marginal marine, and marine shelf sedimentation. The deposits of the systems tracts inherent to these Paleocene-Eocene sequences consist of lowstand fluvial-deltaic, estuarine, tidalinfluenced, and coastal barrier cross-bedded sandstone facies 40 to 100 feet (12 – 30 meters) thick; transgressive nearshore marine shelf glauconitic sandstone and marlstone facies 10 to 40 feet (3 – 12 meters) thick; and highstand fluvial-deltaic, tidalinfluenced, marginal marine, and marine shelf sandstone, siltstone, claystone, and lignite facies 100 to 250 feet (30 – 76 meters) thick.

Stratal architecture is a result of changes in base level. With a relative fall in sea level, the shelf was subaerially exposed and incised, as a result of fluvial processes. A subsequent relative rise in sea level and formation of accommodation resulted in filling of the shelf incisements and incised valleys. During times of erosion and deposition in the Paleocene and Eocene, sands bypassed the shelf and accumulated in deeper-water settings as lowstand fan and wedge facies. These potentially quartz-rich sandstone facies have the potential to be priority petroleum reservoir targets in the offshore northeastern Gulf of Mexico.

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