Structure and chemical petrology of three Southern Appalachians mafic-ultramafic complexes and their bearing upon the tectonics of emplacement and origin of Appalachian ultramafic bodies

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Abstract
Detailed geologic mapping suggests that one of the Blue Ridge bodies studied (Laurel Creek) was emplaced along a pre- to syn-metamorphic thrust. Both Blue Ridge bodies were polydeformed and metamorphosed after emplacement. The Gladesville Complex exhibits are affinities and occur southeast of the Towaliga Fault, a major suture within the Piedmont thrust sheet. Isolated ultramafic (and some gabbro) pods (10 cm to 1-3 km) may represent fragments of ophiolitic slices that became dismembered from the body during subsequent ductile deformation and high grade metamorphism. The behavior of ultramafic and coarse cumulate gabbros ranged from that of relatively soft but coherent "punctured basketballs" to competent "watermelon seed" diapirs moving to zones of lower stress. Formation of hydration haloes may have assisted this process. The changes that occur in these bodies, from low to high metamorphic grade and from relatively undeformed to complexly deformed, compound the difficulties in tracing their origins.--Modified journal

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