EAGER: Collaborative Research: Dating mineralization in a Carlin-type gold deposit: A test of the Fe-oxide (U-Th)/He chronometer

点击翻译按钮获取中文摘要

The Carlin-type gold deposits (CTGDs) of northern Nevada are the source of most of the gold production in the United States and are thus of major economic importance; however, their geologic origin is uncertain. Various models for deposit formation relate the gold mineralization to different geologic events which likely occurred at different times, including magmatic activity, or circulation of groundwater-derived fluids through deeper gold-bearing units in the crust. Because of the lack of easily dateable minerals in CTGDs, it has historically been challenging to determine when gold mineralization occurred. The result is that effective exploration is hampered by the lack of knowledge about how and when these deposits formed. In this study, a new method of dating these deposits will be refined and tested. If the ages of CTGD formation could be more definitively known, gold mineralization could be correlated to broader geologic processes that were occurring at the same time. This knowledge would enable scientists and explorers to more easily discover new deposits.Available geochronological data suggest that Carlin-type mineralization broadly overlapped in space and time with the southwest sweep of Eocene magmatism through Nevada. Geo- and thermochronologic datasets are critical to identify direct evidence that magmatism and ore formation overlapped at individual deposits. Indeed, new chronometric tools could greatly expand knowledge of the genetic processes that lead to CTGD formation. No straightforward method currently exists to date CTDG mineralization. Recent studies have explored the use of the (U-Th)/He chronometer for Fe-oxides, but this chronometer has not been systematically tested in ore deposits. The proposed research has two major goals: to test feasibility of the Fe-oxide (U-Th)/He chronometer to date hydrothermal fluid flow, and to use this method to determine the age of hydrothermal activity in a CTGD in Nevada.