Deformation, geochemistry, and origin of massive sulfide deposits, Gossan lead district, Virginia.
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Resource Abstract:
Lenses and layers of massive sulphides comprise a discontinuous horizon in the late Proterozoic metasedimentary Ashe formation.
The folded and brecciated sulphides include pyrrhotite, minor chalcopyrite, sphalerite and pyrite, and rare arsenopyrite and
galena. The deposits were mined for supergene copper, later for gossan iron, and finally for sulphur. The Ashe formation is
interpreted to be marine turbidites, and contains lenses of mafic rocks of probable tholeiitic basalt parentage. Mineralogically
and chemically distinctive rocks - for the Ashe formation - are interbedded with the sulphides and may represent metamorphosed
alteration zones and/or mixed chemical and clastic sediments. The sulphide deposits are interpreted as syngenetic sediments,
modified by deformation during metamorphism. Their deposition occurred in a deep, elongate marine basin overlying a crustal
rift zone.-G.J.N.
Citation
Title Deformation, geochemistry, and origin of massive sulfide deposits, Gossan lead district, Virginia.