GEOCHEMICAL INVESTIGATION OF CAROLINA TERRANE ROCKS IN THE WOODLAWN AND AONIA QUADRANGLES, GEORGIA

Neoproterozoic to Cambrian greenschist facies rocks of the Persimmon Fork and Richtex Formations along the northwest side of the Little River valley consist of intermediate to felsic subaqueous tuffs and coarse volcaniclastics interlayered with increasing proportions of greenstone, greywacke and mudstone toward the southeast. The succession represents a transition from a proximal volcanic facies dominated by pyroclastic flows and coarse volcaniclastic rocks to an inner distal facies dominated by mudstones and fine tuffaceous rocks. Samples (52) of metavolcanics and associated intrusive rocks were analyzed for major and trace elements by ICP and ICP-MS respectively, using Li-metaborate fusion sample preparation. Classification of metavolcanic rocks using a Zr/Ti-Nb/Y plot indicates the major pyroclastic units are andesites and dacites. Greenstones plot as tholeiitic basalt and basaltic andesite. Tectonic discrimination of the basaltic rocks based on Ti-Zr-Y variation favors arc tholeiite; however, Th-Hf-Ta discrimination suggests calc-alkaline basalts, source enrichment or crustal contamination. Application of granitoid tectonic discrimiantion (Ta-Yb, Nb-Y) schemes to samples of variably foliated quartz diorite, biotite granite and granophyre show a clear volcanic arc affinity suggesting the plutons were essentially coeval with arc volcanism.