GEOLOGICAL INVESTIGATION OF THE CAROLINA TERRANE AND CHARLOTTE TERRANE BOUNDARY IN NORTH CENTRAL SOUTH CAROLINA

Field mapping was recently conducted in dominantly Late Proterozoic rocks in the Piedmont of north central South Carolina in portions of the Rion, Jenkinsville, Chapin, and Richtex quadrangles. This work revealed that the boundary between high-grade, locally migmatitic, gneisses and amphibolites in the Charlotte terrane (CLT) and low-grade metavolcanic and metasedimentary rocks in the Carolina terrane (CT) is a ductile shear zone (SZ) with probable dextral offset. Mylonites in the regionally extensive SZ (possibly the Chappells SZ of Doar, 1995) are strongly lineated and locally have a rotational fabric suggesting dextral shear. A north-northeast trending brittle fault, indicated by prominent outcrops of silicified felsic breccia, has not been traced northward across the SZ. The unmetamorphosed Winnsboro granite (309 Ma) intrudes the CLT, CT, and the SZ and constrains the upper limit for deformation in the area. Thin section analysis of oriented samples, and stereonet analysis of field data should help to determine the relationship between these structural elements.