The primary goals of this proposal are: 1) to determine the formation conditions of a Carlin-type gold deposit, and 2) to either link or separate in time the Getchell gold system and an adjacent 90 Ma granodiorite intrusion and related mineralization. These goals will be accomplished by 1) a detailed petrographic and fluid inclusion study of the gold system to constrain formation pressures and temperature and aqueous fluid chemistry, and 2) a detailed petrographic and fluid inclusion study of quartz veins and tungsten skarn mineralization related to the granodiorite intrusion, to obtain similar constraints. Fluid inclusions will be evaluated by microthermometry and microanalyses including Raman spectroscopy, quadrupole mass spectrometry, and ion chromatography. The Getchell system provides a unique opportunity to examine, in detail, the physical/chemical evolution of a Carlin-type deposit. Preliminary results demonstrate that fluid inclusions present are suitable for microthermometry, Raman spectroscopy, and quadrupole mass spectrometry. This study will document the physical/chemical conditions conducive to gold precipitation and the relationship between gold mineralization and igneous activity in Carlin-type systems. Results will link or separate in time the gold- and intrusion-related mineralization and may place important constraints on the age of gold mineralization in a Carlin-type deposit.
