Newly Discovered Devonian Sedex-type Base and Precious Metal Mineralization, Northern Carlin Trend, Nevada
Poul Emsbo, Richard W. Hutchinson, Albert H. Hofstra, Jeffrey A. Volk, Keith H. Bettles, Gary J. Baschuk, Terry M. Collins, Eric A. Lauha, Jeffrey L. Borhauer, 1997. "Newly Discovered Devonian Sedex-type Base and Precious Metal Mineralization, Northern Carlin Trend, Nevada", Carlin-Type Gold Deposits Field Conference, Peter Vikre, Tommy B. Thompson, Keith Bettles, Odin Christensen, Ron Parratt
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This report presents evidence for a previously unrecognized type of Au mineralization on the Barrick Goldstrike property that is geochemically, mineralogically, and temporally distinct from classic Carlin-type mineralization (Table 1). This newly recognized mineralization is characterized by a mineral assemblage that includes barite, sphalerite, minor boulangerite, pyrite, galena, minor tetrahedrite, tennantite, chalcopyrite and native gold. Gold occurs as native inclusions in pyrite, chalcopyrite, tetrahedrite, bitumen, dolomite, and barite. In contrast, features recognized in Carlin-type deposits include a mineral asemblage of As-rich pyrite, realgar, orpiment, and arsenopyrite, with a distinct absence of base metal sulfides. Gold occurs as sub-micron inclusions in As-rich pyrite and alteration consists of decalcification, silicification, and argillization. Carlin-type mineralization is younger than a 39 Ma dike (Emsbo et al., 1996).
Recognition of the base metal mineralization resulted from a broad study of the breccia-hosted Carlin-type deposit in the Meikle Mine. Examination of the stratigraphic section adjacent to Meikle revealed that these base metal sulfides and barite are stratiform and occur in unaltered rocks of the Popovich Formation. In Meikle, the base metal-rich assemblage also occurs as discordant veins which were brecciated and cut by Carlin-type mineralization (Lamb, 1995). The association of low but significant gold content with this base metal mineralization outside Meikle prompted a study of its geological and spatial characteristics, its age and significance within the geologic evolution of the Goldstrike property, and the relationship of its gold to its other sulfides.
In this abstract we describes textural, stratigraphic/spatial, and geochemical evidence that this base