Depositional History of the Smackover Formation, Appleton Field, Escambia County, Alabama

D. Joe Benson, Lisa M. Pultz, D. D. Bruner, and G. Lu

Appleton Field is a Smackover field situated above two pre-Mesozoic paleohighs near the updip limit of the Smackover in the Conecuh Embayment of southwestern Alabama. Smackover deposition in Appleton Field was influenced by both pre-Smackover paleotopography and sea level fluctuation.

Fourteen lithofacies were identified in the Smackover and the overlying Buckner Anhydrite Member of the Haynesville Formation. These lithofacies were deposited in three depositional stages (early, middle, and late Smackover) that correspond to periods dominated by marine transgression, aggradation, and ultimately progradation.

Early Smackover deposition accompanied a rapid sea level rise that inundated the paleohighs. Rapid sedimentation produced a system that was first transgressive and then aggradational in nature. Algal patch reefs developed around the periphery of the paleohighs and onlapped the structures as sea level rose. Middle Smackover deposition was the result of a decrease in the rate of sea level rise. Tidal flat, lagoon, and shoal complexes formed across topographically higher parts of the field, while subwavebase sediments were deposited off structure. Short-term sea level fluctuations produced seven shallowing-upward packages. During Late Smackover deposition long term sea level was relatively stable allowing the Smackover to aggrade and prograde. Upper Smackover deposits are peritidal domina ted. Short-term sea level fluctuations again produced shallowing upward packages capped in crestal locations by exposure surfaces. With continued sedimentation, supratidal sabkhas formed over the crests of the paleohighs and prograded offstructure during early Buckner deposition. Short term fluctuations in sea level produced a series of shallowing upward sabkha cycles. Development of coastal salinas or restriction of the northern Conecuh Embayment led to deposition of subaqueous evaporites in the upper Buckner.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California