Proterozoic Tectonic Evolution of the Grenville Orogen in North America
Tectonic evolution of the northern Blue Ridge massif, Virginia and Maryland
Published:January 01, 2004
William C. Burton, Scott Southworth, 2004. "Tectonic evolution of the northern Blue Ridge massif, Virginia and Maryland", Proterozoic Tectonic Evolution of the Grenville Orogen in North America, Richard P. Tollo, James McLelland, Louise Corriveau, Mervin J. Bartholomew
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Detailed mapping in the Mesoproterozoic northern Blue Ridge massif has delineated ten high-grade metamorphic map units of mostly granitic composition occurring in association with charnockite and paragneiss. U-Pb isotopic dating of zircons from these rocks defines three episodes of protolith intrusion during the interval from 1150 to 1055 Ma. Crosscutting relationships, structural analysis of foliations and lineations, and comparison of deformational fabrics of gneisses with different protolith ages indicate three episodes of Grenvillian deformation under differing stress regimes: D1, post–1140 Ma and pre–1120 Ma, involving regional coaxial compression; D2, post–1055 Ma and pre–1035 (?) Ma, noncoaxial ductile shear; and D3,...