A Quantitative Method for Measuring Temperature-time Histories in Hydrothermal Magmatic Ore Systems

热液岩浆矿石系统温度-时间历史测量的定量方法

• 批准号: 1220252
• 负责人: Drew Coleman
• 金额: $ 21.7万
• 依托单位: University of North Carolina at Chapel Hill
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1220252&HistoricalAwards=false
• 关键词: Quantitative; Method; Measuring; Temperature; time

In 2010, the United States produced over $800 million of molybdenum oxide, and the demand for molybdenum as an alloying agent in high-grade steel will likely increase as global economies recover. The majority of the world's molybdenum reserves are contained within porphyry copper (±molybdenum) and porphyry molybdenum (±copper) deposits. Although porphyry molybdenum deposits are often volumetrically smaller than porphyry copper systems, they are still a significant source of molybdenum owing to higher ore grades. Understanding porphyry molybdenum deposition is important for accurate predictions of spatial and temporal ore distribution during exploration. The timing and duration of molybdenum mineralization relative to associated magmatism will be investigated. The study will lend insight into the complex variations of ore grade, alteration geochemistry, and magmatic-hydrothermal textures observed within porphyry molybdenum ore systems.Detailed uranium/lead zircon (±titanite) and argon/argon biotite (±hornblende) dating of plutonic rocks associated with porphyry molybdenum deposits in the western US will be obtained. In addition, rhenium/osmium molybdenite dates, and fluid trapping temperatures for molybdenite in quartz veins from economically important deposits will be determined. These data will be used to establish precise temperature-time histories of the deposits and the timing of mineralization within the thermal maturation of the magma system. This information should be useful in enhancing exploration for molybdenum - an increasingly valuable international commodity. The results of this work should 1) enable better understanding of porphyry mineralization in light of new hypotheses regarding the incremental assembly of homogeneous plutons, and 2) further development of combined rhenium/osmium geochronology and fluid inclusion thermometry as a broadly applicable thermochronologic tool.

2010年，美国生产了超过8亿美元的氧化钼，随着全球经济复苏，作为高级钢的合金剂的钼的需求可能会增加。世界上大多数钼储量都包含在斑岩铜(±钼)和斑岩钼(±铜)矿床中。尽管斑岩钼矿床的体积往往小于斑岩铜矿系统，但由于矿石品位较高，它们仍是钼的重要来源。了解斑岩钼矿床对于准确预测勘查过程中矿石的时空分布具有重要意义。将研究与相关岩浆作用有关的钼成矿的时间和持续时间。这项研究将深入了解斑岩钼矿系统中观察到的矿石品位、蚀变地球化学和岩浆-热液结构的复杂变化。将获得美国西部与斑岩钼矿有关的深成岩的铀/铅-锆石(±钛铁矿)和Ar/Ar黑云母(±角闪石)年龄。此外，还将确定具有重要经济价值的矿床石英脉中辉钼矿的Re/os辉钼矿年龄和流体捕集温度。这些数据将被用来建立准确的矿床温度-时间历史和岩浆系统热成熟过程中的矿化时间。这些信息应有助于加强对钼的勘探，钼是一种越来越有价值的国际商品。这项工作的结果应该：1)根据关于均质深成岩增量组装的新假设，更好地理解斑岩成矿作用；2)进一步发展Re/Om年代学和流体包裹体测温相结合的方法，使之成为一种广泛适用的热年代学工具。