Abstract: Paleotopographic Vs Eustatic Controls on Deposition of the Smackover Formation, Appleton Field, Escambia County, Alabama

D. Joe Benson, Lisa M. Pultz, D. D. Bruner

Appleton Field is a Jurassic Smackover Field situated above two pre-Mesozoic paleohighs in the northern part of the Conecuh Embayment of southwestern Alabama. The interplay between paleotopography and sea level fluctuation controlled Smackover deposition and reservoir development in Appleton Field.

The Smackover Formation and the overlying Buckner Anhydrite Member of the Haynesville Formation were deposited in three depositional stages that correspond to periods dominated by marine transgression, aggradation, and ultimately progradation.

Lower Smackover deposition accompanied a rapid sea level rise that inundated much of the paleohighs and produced a depositional system that was first transgressive and then aggradational in nature. Algal patch reefs developed around the periphery of the paleohighs and onlapped the features as sea level rose. Middle Smackover deposition accompanied a decrease in the rate of sea level rise. Tidal flat, lagoon, and shoal complexes formed in topographically higher parts of the field, while sub-wavebase sediments were deposited in deeper waters off structure. Short-term sea level fluctuations produced seven shallowing-upward packages. During upper Smackover deposition, sea level was relatively stable allowing the Smackover to aggrade and prograde. Upper Smackover deposits are peritidal dom nated. Short-term sea level fluctuations 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 off-structure during lower Buckner deposition. Short-term sea level fluctuations produced a series of shallowing-upward sabkha cycles. Development of coastal salines or restriction of the northern Conecuh Embayment led to deposition of subaqueous evaporites in the upper Buckner.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas