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

EAGER：合作研究：卡林型金矿床中的矿化年代测定：铁氧化物 (U-Th)/He 天文计的测试

• 批准号: 1641138
• 负责人: William Guenthner
• 金额: $ 2.8万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1641138&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Dating; mineralization

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.

内华达州北部的Carlin型黄金矿床（CTGD）是美国大多数黄金产量的来源，因此具有重要的经济意义；但是，它们的地质起源尚不确定。用于沉积形成的各种模型将黄金矿化与可能在不同时间发生的不同地质事件相关联，包括岩浆活性，或通过地壳中更深的金含金单元的地下水衍生的流体循环。由于CTGD中缺乏易于可数据的矿物质，从历史上看，确定何时发生黄金矿物质一直具有挑战性。结果是缺乏对这些沉积物的形成以及何时形成的知识，从而阻碍了有效的探索。在这项研究中，将对这些沉积物进行约会的新方法进行完善和测试。如果CTGD形成的年龄可以更明确地知道，则黄金矿化可能与同时发生的更广泛的地质过程相关。这些知识将使科学家和探险者更容易发现新的沉积物。可弥补的年代学数据表明，卡林型矿化矿化在时空和时间上与西南始新世岩浆通过内华达州的西南扫地广泛重叠。地理和热相导数据集对于确定直接证据表明岩浆和矿石形成在单个沉积物上重叠的证据至关重要。确实，新的计时工具可以大大扩展对导致CTGD形成的遗传过程的知识。迄今为止，目前尚无直接方法CTDG矿化。最近的研究探索了（u-t​​h）/He计时仪用于氧化物的使用，但是该天文典礼表并未在矿石沉积中系统地测试。拟议的研究有两个主要目标：测试fe-氧化物（u-th）/He Chronometer的可行性，以盖上热液流体流量，并使用这种方法来确定内华达州CTGD中的热液活性的年龄。