ABSTRACT

The Smackover Formation (Jurassic, Oxfordian) in the Conecuh Basin, Escambia County, Alabama, is divided into six carbonate sedimentary facies. In approximate stratigraphic order, they are: 1) intertidal algal mudstone; 2) basinal carbonate mudstone and calcareous shale; 3) graded slope packstone and wackestone; 4) Tubiphytes-bearing, slope debris-flow grainstone and packstone; 5) distal-ramp wackestone; and 6) shoal-produced oolitic grainstone.

Facies correlation and synthesis using 11 key drill cores shows that the Smackover platform was profoundly affected by two rapid sea-level rises during the Oxfordian transgression as well as the Late Oxfordian regression. The first rapid rise drowned the inherited Norphlet clastic ramp including the Smackover intertidal algal mudstone (Facies 1). Subsequently, a Tubiphytes-rimmed shelf developed, and its bypass-margin slope deposits (Facies 3 and 4) and coeval basinal facies (Facies 2) prograded into the basin. The second rapid sea-level rise drowned the rimmed shelf, thereby creating a distally steepened ramp. Facies developed on the ramp were distal-ramp deposits (Facies 5) and higher energy up-dip oolitic shoals (Facies 6). The Late Oxfordian rapid regression caused widespread progradation of the oolitic shoals and coeval sabkha facies of the overlying Buckner Anhydrite.