The Paleozoic Black Warrior foreland basin on the southeastern edge of the North American craton in Alabama and Mississippi is similar to other foreland basins along the Appalachian-Ouachita orogen (Fig. 1). The eastern part of the basin is exposed in north-central Alabama, but the western part is covered by Mesozoic-Cenozoic strata of the Gulf Coastal Plain (Mellen, 1947). A regional pre-Mesozoic unconformity truncates Paleozoic strata and dips gently southwestward toward the broad southward-plunging syncline that defines the Mississippi Embayment of the Gulf Coastal Plain (Fig. 1) (Thomas and others, in press).
The oldest sedimentary rocks in the Black Warrior basin are of Cambrian age and rest unconformably on Precambrian crystalline basement rocks. The youngest strata of the Paleozoic succession are of Pennsylvanian age. The Pennsylvanian rocks are unconformably overlain by Cretaceous strata in the western part of the basin and are exposed in the eastern part. The Paleozoic succession includes two distinctly different parts: Cambrian to Early Mississippian shallow-marine shelf facies indicating a passive continental margin, and later Mississippian to Pennsylvanian shallow-marine to deltaic facies reflecting evolution of a foreland basin (Plate 8).
Structurally, the Black Warrior foreland basin is a homo-cline that dips southwestward away from the craton and extends beneath the front of the Paleozoic Appalachian-Ouachita fold-thrust belt (Fig. 1; Plate 8 A). Subsurface data demonstrate continuity of the Paleozoic fold-thrust belt south of the Black Warrior basin from Appalachian outcrops in Alabama, beneath the Gulf Coastal Plain, to the Ouachita Mountains in Arkansas (Fig. 1) (Thomas, 1973, 1985, in press).
Figures & Tables
Sedimentary Cover—North American Craton
The “sedimentary cover” refers to the stratified rocks of youngest Proterozoic and Phanerozoic age that rest upon the largely crystalline basement rocks of the continental interior. The early chapters of the volume present data and interpretations of the geophysics of the craton and summarize, with sequential maps, the tectonic evolution of the craton. The main body of the text and accompanying plates and figures present the stratigraphy, structural history, and economic geology of specific sedimentary basins (e.g., Appalachian basin) and regions (e.g., Rocky Mountains). The volume concludes with a summary chapter in which the currently popular theories of cratonal tectonics are discussed and the unresolved questions are identified.