ABSTRACT: The Black Warrior Foreland Basin and the Diachronous Appalachian-Ouachita Thrust Belt

THOMAS, WILLIAM A., University of Kentucky, Lexington, KY

The Black Warrior foreland basin, a southwest-dipping homocline, extends beneath the northwest-striking Ouachita thrust belt (now covered by postorogenic strata of the Gulf Coastal Plain), and it is bordered on the southeast by the northeast-striking Appalachian thrust belt. A southwestward-thickening, northeastward-prograding, deltaic to shallow marine, Upper Mississippian to Middle Pennsylvanian synorogenic clastic wedge overlies preorogenic, passive-margin shelf facies and fills the foreland basin. Mississippian clastic facies grade northeastward to carbonate, and facies distribution throughout the wedge conforms to northwesterly stratigraphic strike. Structure and stratigraphy indicate that the Black Warrior basin is an Ouachita foreland basin rather than an Appalachian foreland b sin. Ouachita thrust loading on the southwest and northeastward dispersal of clastic sediment began in the Meramecian and continued into Middle Pennsylvanian, but the younger (late Early Pennsylvanian) part of the clastic wedge includes some components that prograded northwestward from an Appalachian source, indicating initiation of northwest-directed thrusting. The southeastern part of the southwest-dipping foreland basin subsequently was dismembered and displaced northwestward by Appalachian thrusting. Mississippian-Pennsylvanian clastic facies in northeast-striking Appalachian synclines are distributed similarly to those in the Black Warrior basin, indicating that the palinspastic location of the Appalachian thrust sheets was within the Ouachita foreland. The clastic succession in dee Appalachian synclines is much thicker than that in the Black Warrior basin, indicating that the foreland basin was partitioned by the down-to-southeast, northeast-striking Birmingham basement fault system (now beneath Appalachian thrust sheets). Strata in the Appalachian thrust belt record the filling of the Black Warrior basin in the Ouachita foreland and the subsequent northwestward thrusting of the original southeastern part of the basin.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)