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Volcanic rock-hosted gold and base-metal mineralization associated with Neoproterozoic-Early Paleozoic back-arc extension in the Carolina terrane, southern Appalachian Piedmont

Feiss, P. Geoffrey ; Vance, R. Kelly ; Wesolowski, David J.

Geology, May, 1993, Vol.21(5), p.439(4) [Periódico revisado por pares]

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  • Título:
    Volcanic rock-hosted gold and base-metal mineralization associated with Neoproterozoic-Early Paleozoic back-arc extension in the Carolina terrane, southern Appalachian Piedmont
  • Autor: Feiss, P. Geoffrey ; Vance, R. Kelly ; Wesolowski, David J.
  • Assuntos: Minerals (Geology) -- Research ; Volcanic Rocks -- Research
  • É parte de: Geology, May, 1993, Vol.21(5), p.439(4)
  • Descrição: Volcanogenic mineral deposits in the Carolina terrane, southern Appalachian Piedmont, include Kuroko-type polymetallic massive sulfide deposits and disseminated gold-pyrite deposits associated with propylitic, silicic, argillic, and advanced argillic alteration. Host rocks are metavolcaniclastic and metaepiclastic rocks of a Neoproterozoic-Early Cambrian magmatic arc. The favorable gold horizon is the transition from a lower succession of andesitic and rhyolitic pyroclastic rocks with basal mafic lavas to an upper sequence of epiclastic sedimentary units and minor lava and ash flows. Kuroko-type deposits are associated with mafic to bimodal volcanic rocks in the upper sequence. Whole-rock oxygen isotope analyses indicate that gold mineralization is associated with a transition from hydrothermal systems dominated by isotopically relatively light (Delta-18O = -6 per thousand to -10 per thousand) waters, typical of high-latitude subaerial systems, to seawater (Delta-18O = 0 per thousand). Plots of Delta-18O vs. SiO2 of the host rocks show a compositional gap associated with mineralization at the subaerial to submarine transition. Values of Delta-18O for the hydrothermal waters, lithostratigraphic analyses, and tectonic models of the Carolina terrane demonstrate that mineralization coincided with extension in a rifted arc.

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