Matthew Huebner of LCI has authored a technical paper entitled, “Confirmation of the southwest continuation of the Cat Square terrane, southern Appalachian Inner Piedmont, with implications for middle Paleozoic collisional orogenesis”. Matthew’s co-authors are Robert D. Hatcher Jr. and Arthur J. Merschat.
Detailed geologic mapping, U-Pb zircon geochronology and whole-rock geochemical analyses were conducted to test the hypothesis that the southwestern extent of the Cat Square terrane, southern Appalachians, continues from the northern Inner Piedmont (western Carolinas) into central Georgia. Geologic mapping revealed the Jackson Lake fault, a ~15 m-thick, steeply dipping sillimanite-grade fault zone that truncates lithologically distinct granitoids and metasedimentary units, and roughly corresponds with a prominent aeromagnetic lineament hypothesized to represent the southern continuation of the terrane-bounding Brindle Creek fault. Based primarily on a distinct partitioning of granitoid ages and lithologic distinctions similar to the northern Inner Piedmont, the rocks southeast of the Jackson Lake fault are interpreted to represent the southwestern extension of the Cat Square terrane. Data suggest Cat Square terrane metasedimentary rocks were initially deposited in a remnant ocean basin setting, and developed into an accretionary prism in front of the approaching peri-Gondwanan Carolina superterrane, ultimately overridden by it in the Devonian to Early Mississippian Acadian/Neoacadian orogeny. Burial to >20 km resulted in migmatization of lower plate rocks, forming an infrastructure beneath the Carolina superterrane suprastructure. Provenance patterns support ~250 km of Devonian dextral translation of the composite Inner Piedmont relative to Laurentia. The megascopic thrust-nappe structural style of the northern Inner Piedmont, combined with southwest-directed lateral extrusion at mid-crustal depths, is suggested to reconcile differences in timing of metamorphism between the Carolina and central Georgia Inner Piedmont and structural contrasts between the Brindle Creek and Jackson Lake faults. A copy of publication is available at American Journal of Science.