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

内华达州北部的卡林型金矿（CTGDs）是美国大部分黄金生产的来源，因此具有重要的经济意义；然而，它们的地质起源是不确定的。金矿形成的各种模型将金矿化与可能发生在不同时期的不同地质事件联系起来，包括岩浆活动，或通过地壳中更深的含金单元的地下水衍生流体的循环。由于ctgd中缺乏易于确定年代的矿物，因此确定金矿化发生的时间一直具有挑战性。结果是，由于缺乏对这些矿床形成的方式和时间的了解，有效的勘探受到了阻碍。在这项研究中，将改进和测试一种测定这些沉积物年代的新方法。如果能更明确地知道CTGD形成的年代，那么金矿化就可以与同时发生的更广泛的地质过程联系起来。这些知识将使科学家和探险家更容易发现新的矿藏。现有的年代学资料表明，卡林型成矿作用在空间和时间上与始新世岩浆活动横扫内华达州的西南方向广泛重叠。地质和热年代学数据集对于确定岩浆活动和成矿在个别矿床重叠的直接证据至关重要。事实上，新的计时工具可以极大地扩展导致CTGD形成的遗传过程的知识。目前还没有直接的方法来确定CTDG的矿化。最近的研究已经探索了使用(U-Th)/He计时器来测定铁氧化物，但这种计时器还没有在矿床中进行系统的测试。提出的研究有两个主要目标：测试Fe-oxide (U-Th)/He计时器测定热液流动的可行性，并使用该方法确定内华达州CTGD中热液活动的年龄。

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.