ABSTRACT

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, sea-level fluctuation, and carbonate productivity controlled Smackover deposition in Appleton field.

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

Lower Smackover deposition accompanied a rapid sea-level rise that inundated much of the paleotopography 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 subwavebase sediments were deposited in deeper waters off structure. Short-term sea-level fluctuations produced seven shallowing-upward packages. During upper Smackover deposition, carbonate productivity outpaced sea level rise allowing the system to aggrade and prograde and producing deposits that are peritidal dominated. 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 offstructure during lower Buckner deposition. Short-term sea-level fluctuations 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.