Duration of Mineralization in Young Porphyry Systems through Rhenium-Osmium (Re-Os) Dating

SteinEAR-0087483该项目解决了了解与地壳浅层岩浆作用有关的铜钼矿床的地质过程所需的基本基础之一。这一基础是在岩浆作用和地体的构造和地质演化的更广泛的背景下成矿过程的时间和持续时间。有人说：“没有约会，就没有房租！”使用现在建立的Re-Os(Re-Os)测年方法，这是唯一直接测定硫化物矿石矿物年龄的方法，这项研究解决了形成所谓斑岩铜钼矿床所需的时间跨度。它们是在数千万年(或更长时间)内形成的，还是在几十万年(或更短时间)内形成的？以前测定矿石沉积时间的尝试受到一些技术的限制，这些技术可能涉及与矿石有关的矿物和/或不保留成矿年龄的技术。例如，一种测年技术涉及到使用Ar(Ar)，这是一种处于自然状态的气体，尽管Ar可能在岩石和矿物中被发现和测量，但这并不是一个适合这种元素的地方。相反，Re和Os都是亲硫化物的，自然地集中在金属矿石矿物中。这项Re-Os研究的结果将与其他测年方法得出的年龄结果进行比较。这项研究将重点研究与两个年轻的岩浆系统有关的矿化作用，这两个岩浆系统拥有巨大的钼和铜矿床，科罗拉多州的经典亨德森钼矿和智利的洛斯佩兰布雷斯铜钼矿。

SteinEAR-0087483This project addresses one of the fundamental underpinnings needed to understand geologic processes that produce copper-molybdenum deposits associated with magmatism at shallow levels in the earth's crust. This underpinning is the timing and duration of the mineralization process within the broader context of the magmatism and the tectonic and geologic evolution of a terrane. It has been said: "No Dates, No Rates!" Using the now established Re-Os (rhenium-osmium) method of dating, the only method that directly dates the sulfide ore minerals themselves, this study addresses the time span needed to form so-called porphyry copper-molybdenum deposits. Do they form over tens of millions of years (or more), or do they form in a few hundred thousand years (or less)? Previous attempts at dating the time of ore deposition were limited by techniques that addressed presumably ore-associated minerals and/or techniques that do not retain the age of mineralization. For example, one dating technique involves the use of Ar (argon), a gas in its natural state, and although Ar may be found and measured in rocks and minerals, this is not a comfortable site for the element. In contrast, both Re and Os are sulfide-loving, and are naturally concentrated in metallic ore minerals. The results from this Re-Os study will be compared with age results derived from other methods of dating. This study will focus on dating mineralization associated with two young magmatic systems that host giant deposits of molybdenum and copper, the classic Henderson molybdenum deposit in Colorado and the Los Pelambres copper-molybdenum deposit in Chile.