Facies Analysis, Sea Level History, and Platform Evolution of Jurassic Smackover Formation, Conecuh Basin, Escambia County, Alabama

Richard A. Esposito, Jr., David T. King, Jr.

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, show 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 in the basin. The second rapid sea level rise drowned the rimmed shelf, creating a distally steepened ramp. Facies developed on the ramp were distal-ramp deposits (facies 5) and higher energy updip oolitic shoals (facies 6). The late Oxfordian rapid regression caused widespread progradation f the oolitic shoals and coeval sabkha facies of the overlying Buckner anhydrite.

AAPG Search and Discovery Article #91042©1987 GCAGS and GC-SEPM Section Meeting, San Antonio, Texas, October 28-31, 1987.