Structure of the Kelley Mountain culmination, central Alabama, and implications for the evolution of the southeastern southern Appalachian foreland thrust belt

The Kelley Mountain structural culmination forms a half window with respect to the metamorphic Talladega-Cartersville thrust sheet. Fault rocks along one of the contacts within this half window indicate that this contact is a thrust fault. Based on regional structural relationships, this contact is interpreted as the Pell City fault, a regional thrust fault within the Alabama foreland thrust belt northwest of the Talladega-Cartersville fault. Therefore, the Kelley Mountain culmination is interpreted as an eyelid window exposing the Pell City and Talladega-Cartersville faults. The Pell City thrust sheet at Kelley Mountain is interpreted as a horse beneath the Talladega-Cartersville fault that has moved up a footwall ramp through Cambrian-Ordovician carbonates and onto a flat of Mississippian shale and sandstone. A similar thrust geometry at the Fort McClellan window, 90 km to the northeast, indicates that the Pell City thrust sheet may be a large horse associated with a regional footwall ramp. Both the Talladega-Cartersville and Pell City faults are folded by the Kelley Mountain antiform and adjacent Columbiana synform. The Kelley Mountain antiform continues northward from the Kelley Mountain area to the southern terminus of the Coosa deformed belt, where shortening associated with folding may be transferred to imbricate faulting in the footwall of the Pell City fault.