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1	MINERAL PARAGENESIS, GEOCHEMISTRY AND GEOCHRONOLOGY INVESTIGATIONS OF THE CARLIN-TYPE GOLD DEPOSITS AT THE GOLDSTRIKE PROPERTY, NORTHERN NEVADA: IMPLICATIONS FOR ORE GENESIS, IGNEOUS PETROGENESIS AND MINERAL EXPLORATION ALMEIDA, CAROLINA 27 September 2009 (has links) The Goldstrike property is located in northern Nevada and contains one of the largest and highest-grade Carlin-type gold deposits. The majority of the Eocene Au mineralization (e.g., Ore I) is hosted in intensely altered Paleozoic lower-plate impure carbonate rocks, and is characterized by strong to moderate silicification, higher calculated pyrite and ore-related element concentrations (e.g., As, Cu, Hg, Ni, Tl, Sb, W, and Zn) than Ore II, which is weakly altered. However, both ore types contain similar Au concentration in whole rock and pyrite chemistry analyses. Lithogeochemical and microprobe data suggest that the Paleozoic sedimentary rocks may have been a major source of Cd, Mo, Ni, U, V, and Zn and minor As, Cu, Hg, and Se. The Jurassic lamprophyre dikes might have been a significant source of Ba, Co, and Se, and minor Au, and some of the Jurassic and Eocene intrusive rocks may have provided some Fe. Moreover, the Eocene magmas are interpreted to be the main source of auriferous mineralizing fluids and ore-related elements. Trace element abundances and ratios of the Jurassic intrusive rocks suggest that they are shoshonitic and formed from a metasomatized mantle-derived magma, crystal fractionation, and crustal contamination. The Eocene dikes, also shoshonitic, are considerably more evolved and contaminated than the studied Jurassic rocks. Furthermore, Ar-Ar results show that the Jurassic intrusive rocks were negligibly affected by the Eocene thermal event, and that temperature of mineralizing fluids were below the closure temperature of biotite (> 3500C). A magmatic-related model is proposed to explain the formation of the Carlin-type gold deposits at the studied area. In this model, Au and the ore-related elements were exsolved along with volatiles by degassing of a deep and large plutonic complex during its early stage of crystallization. As these magmatic-hydrothermal fluids moved upward along major conduits (e.g., NNW-striking faults), they may have interacted with a Fe-rich fluid, pervasively altering the Paleozoic impure carbonate rocks (e.g., carbonate dissolution, silicification, pyritization) and forming Ore I. Subsequently, these fluids moved laterally further away from the major conduits, became cooler, less acidic, and depleted in ore-related elements and interacted with the Fe-bearing host rocks (e.g., sulfidation), favoring the precipitation of Ore II. / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2009-09-25 21:37:33.76 Carlin-type gold deposits magmatic-related Goldstrike property Eocene metal sources
2	Petrology of Gold Ore-Bearing Carbonates of the Helen Zone, Cove Deposit, Lander County, Nevada Pacanovsky, Aaron James 05 June 2014 (has links) No description available. Geology Mining Mineralogy Petrology Cove Deposit Helen Zone carbonate gold Carlin type Nevada McCoy Mining District Home Station Member Favret Formation
3	Gold-bearing carbonate, sulfide, and silicate veining in igneous and sedimentary lithologies of the Helen Zone, Cove Deposit, Fish Creek Mountains, Nevada Gilbow, Justin R. 10 June 2016 (has links) No description available. Chemistry Earth Environmental Geology Environmental Science Geochemistry Geological Geology Materials Science Metallurgy Mineralogy Mining Mining Engineering Petrology Sedimentary Geology gold Au carlin-type carlin-style silver Ag platinum Pt arsenic veins veining carbonate sulfide silicate igneous sedimentary lithologies helen zone McCoy Cove fish creek mountains Nevada disseminated bisulfide hydrothermal fluids

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