M.S. Thesis Defense by Patrick Quillen—April 20
Buffalo Canyon: An Oligocene Greisen-Like Reduced Intrusion-Related Gold Deposit in the Union Mining District, Nye County, Nevada
Advisor: Dr. John Muntean
Thursday, April 20th at 1:00 p.m., LME 415
Buffalo Canyon is a gold prospect located near the historic Berlin mining area in the Union district of northern Nye County, Nevada. LA-ICPMS dating of zircon (U-Pb) from 11 samples reveal three distinct periods of magmatism – in the late Jurassic (162 to 158 Ma), the late Cretaceous (83 to 77 Ma), and the Oligocene (25 to 24 Ma). Oligocene intrusive rocks are intermediate to felsic, metaluminous to weakly peraluminous and locally ilmenite bearing. Muscovite + tourmaline alteration is locally pervasive within Oligocene intrusions. Mineralization is defined by free gold-bearing, sheeted, crack-seal quartz veins that locally contain muscovite, tourmaline and fluorite within veins and as envelopes. Veins have a Au-Te-(Mo-Bi-Sn) elemental association, high Au:Ag ratios (>1:1) and are hosted in both hornfelsed country rocks and weakly in Oligocene intrusions. Veins contain common hypersaline brine and coexisting vapor-rich fluid inclusions, which combined with thicknesses of coeval Oligocene volcanic rocks suggest estimated paleodepths of < ~3 km for deposit formation. Mineralization strongly resembles typical reduced intrusion-related gold systems that are well defined in Alaska and Yukon, but only a few examples have been documented in Nevada.