Tectonics and geoarchaeology of some metaultramafic rocks in the southern Appalachians

Abstract

Metaultramafic rocks are wide-spread in the Appalachian Orogen and have been used in tectonic reconstructions. The Tugaloo Terrane extends from Alabama to Maryland containing two belts of ultramafic rocks, one in the Blue Ridge and one in the Inner Piedmont; Hess first described the belts. Normative mineralogy and comparison to various ophiolite sections shows that Blue Ridge rocks are related to arc volcanism and Piedmont rocks formed in a fore-arc setting. Ancient Native Americans have quarried the metaultramafic rock soapstone. An inherent assumption in soapstone provenance studies is the homogeneity of soapstone mineralogy on the outcrop scale. Joseph Bond Quarry (18HO1) was used to test this assumption. Mineralogy proved uniform except for differences in talc and chlorite compositions between amphibole-bearing and amphibole-free assemblages. In future applications of soapstone mineralogy it will be important to take into account the roles of different assemblages in explaining variations in mineral compositions.