Dating gold deposition in a Carlin-type gold deposit using Rb/Sr methods on the mineral galkhaite

Significant effort has been expended in an attempt to date hydrothermal act ivity that generated Carlin-type gold deposits (CTDs) in the Great Basin of Nevada. Thus far, these efforts have been only partially successful, becau se the relationship(s) between the dated mineral and hydrothermal activity are equivocal in many cases. Galkhaite, a trace component of at least four CTDs in Nevada, contains significant amounts of Rb and virtually no Sr, mak ing it an ideal candidate for radiometric dating, At the Getchell deposit, galkhaite is paragenetically late, but clearly associated with gold mineral ization. Our data place gold mineralization at Getchell at 39.0 +/- 2.1 Ma. This is the first unequivocally gold-related date produced for any of the Carlin-type systems. Galkhaite also has been reported at the Carlin, Rodeo, and Betze deposits and is likely present in other CTDs in Nevada. This min eral may provide a solution to the conundrum of dating of CTDs.