Petrotectonics of Mafic and Ultramafic Rocks in Blue Ridge Terranes of Western North Carolina and Northern Georgia

The purpose of this paper is to summarize the geochemical, petrologic and mineralogic data on the mafic and ultramafic rocks in the eastern Blue Ridge province of the southern Appalachian orogen and to relate these rocks to the various terranes postulated for this area. The recent use of high resolution ion microprobe geochronology (Carrigan et al., 2003; Bream et al., 2004; Hatcher et al., 2004; Ownby et al., 2004), coupled with detailed geologic mapping has resulted in an evolving concept of terranes in the this area (Hatcher et al., 1999, 2004, this volume, Hatcher, 2001). Tectonostratigraphic terranes are recognized based on their faulted boundaries, crustal affinity, age, and tectonic history. For the purposes of this paper, we adopt the terminology and distribution of these terranes as depicted in this guidebook (Hatcher, this volume), but recognize that delineation of terranes is an evolving process and that terrane boundaries are subject to reinterpretation based on new data. With the goal of using ultramafic rocks to help unravel the character and history of these packages of rock, we present a review of the character of the ultramafic and associated mafic rocks.