Composition of Carboniferous sandstones and tectonic framework of southern Appalachian-Ouachita orogen

Abstract

Abstract Studies in the Appalachian fold and thrust belt and Black Warrior foreland basin in Alabama indicate deposition of two converging clastic wedges. A northeastward-prograding clastic wedge (Floyd-Pride Mountain-Hartselle-Parkwood) reached Alabama by late Meramecian time; progradation continued with deposition of the Lower Pennsylvanian Pottsville Formation. A southwestward-prograding clastic wedge (Pennington-Pottsville) appeared in Alabama in late Mississippian. Foliated quartz-mica rock fragments, unstable polycrystalline quartz, pelitic rock fragments, and polycyclic monocrystalline quartz suggest that the largest and/or most proximal source-rock province was a low-grade metamorphic and sedimentary fold-thrust belt. Detrital chert suggests derivation from a subduction complex or from bedded chert incorporated in a fold-thrust belt. Andesitic + or - basaltic and dacitic volcanic rock fragments indicate the presence of an arc complex. A complex source terrain produced by juxtaposition of a fold-thrust belt, subduction complex, and arc suggests collision of the Alabama promontory of the southern margin of North America with an arc or with a microcontinent and associated continental-margin arc.--Modified journal abstract.