Age of Formation of Carlin-Type Gold Deposits and Relationship to Tectonic Environments

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9805384ArehartCarlin-type gold deposits (CTDs) are a major focus of mining and exploration activity in the US today, yet processes leading to their genesis are poorly understood. The goal of this research is to investigate the causes and conditions of Carlin-type gold deposit formation by addressing questions regarding the timing of deposition and the relationship between hydrothermal circulation, ore deposition, and magmatic and tectonic events. Of particular importance is resolution of the question of whether there is a common theme responsible for CTD formation either through magmatic association or unique tectonic environment. In order to address the fundamental issue of CTD formation age several avenues will be followed at individual deposits in the Carlin Trend: acquisition and synthesis of geological, petrological and structural data; stable isotope comparison of mineralizing fluids with secular curves for meteoric waters; conventional and laser-assisted argon geochronology on igneous rocks and alteration minerals; fission-track dating of apatite and zircon; and U-Pb dating of hydrothermal apatite. In addition, the applicability of the rhenium-osmium system for direct dating of gold-bearing sulfides will be explored. By understanding the timing of ore deposition additional constraints will be placed on the potential sources of fluids and heat to drive hydrothermal circulation in Carlin-type gold deposits.