STRETCHED PEBBLE ANALYSIS OF THE CHEAHA QUARTZITE IN THE ALABAMA SOUTHERN APPALACHIAN MOUNTAINS

Deformation in the Southern Appalachian Mountains is typically correlated with one of three phases of Paleozoic orogenesis: the Ordovician Taconic, the Silurian-Devonian Acadian/Neoacadian, and the Pennsylvanian-Permian Alleghenian. The age and sequence of structural development in metamorphic rocks in the Appalachian Piedmont may be more complex than previously hypothesized. Geologic mapping and structural analysis on Porter Gap and Clairmont Springs 7.5-minute quadrangles in east central Alabama, is expected to establish a relationship between early Mississippian metamorphism and thrust faults containing the Talladega Group. Currently, metamorphism in the area is bracketed to Late Devonian -Mississippian in age. It is currently unknown if thrust fault juxtaposition occurred at depth around the same time as metamorphism or if the faulting post-dates metamorphism and thus deformed previously metamorphosed rock units. To test these models, we present structural data, including stretched pebble conglomerate measurements, to assess the relative ages of metamorphism, deformation, and uplift compare to those age estimates for orogenesis in the southern Appalachians. Clasts are roughly aligned E-W, which does not vary across strike changes along a map scale oroclinal bend. We interpret a previously unmapped regional thrust fault that may be responsible for clast elongation and records thrust fault transport during early Alleghenian deformation.