Geology and geochemistry of granitic and charnockitic rocks in the central Lovingston massif of the Grenvillian Blue Ridge terrane
Published:January 01, 2004
Scott S. Hughes, Sharon E. Lewis, Mervin J. Bartholomew, A. Krishna Sinha, Norman Herz, 2004. "Geology and geochemistry of granitic and charnockitic rocks in the central Lovingston massif of the Grenvillian Blue Ridge terrane", Proterozoic Tectonic Evolution of the Grenville Orogen in North America, Richard P. Tollo, James McLelland, Louise Corriveau, Mervin J. Bartholomew
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Basement rocks of the Lovingston massif in the central Blue Ridge anticlinorium include jotunite, anorthosite, charnockitic rocks, and related Fe-Ti oxide- and apatite-rich rocks that display strong similarities to lithologic assemblages elsewhere in the Grenville orogen. The rock units preserve evidence of a protracted history of granulite-facies metamorphism and plutonism from ca. 1.15 to ca. 1.0 Ga, followed by multiple episodes of lower-grade Paleozoic metamorphism. New whole-rock major-and trace-element data indicate systematic chemical trends, incompatible element enrichments relative to the lower crust, and overall uniformity among Lovingston rocks. Quantitative geochemical models and field associations support interpretation of the Grenvilleage Archer Mountain Suite and Turkey Mountain Suite plutonic series as being derived from lower crustal sources. Archer Mountain Suite biotite granitoids and leucocratic granitoids and younger Roseland Anorthosite (with the associated Roses Mill pluton) and charnockitic plutons contain a substantial amount of lower crustal chemical component that is equivalent to the average Stage Road Suite. We propose that all of the Grenvilleage rocks in the Lovingston massif are related to a broad igneous protolith, represented by the Stage Road Suite, from which remobilized magmatic bodies were derived during orogenesis. Chemical data further indicate that Neoproterozoic intrusions and/or mylonitization along the Rockfish Valley fault had only minor local effects on highly mobile elements near their contacts or localized in shear zones.