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

Steinberg-0087483该项目解决了理解地质过程所需的基本基础之一，这些地质过程产生了与地壳浅层岩浆活动有关的铜钼矿床。 这一基础是在岩浆作用和构造和地质演化的更广泛背景下成矿过程的时间和持续时间。 有人说：“没有日期，没有费率！“这项研究使用现已建立的Re-Os（铼-锇）测年方法，这是直接测定硫化矿矿物本身年龄的唯一方法，研究了形成所谓的斑状铜钼矿床所需的时间跨度。 他们是在几千年（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？ 以前尝试测定矿石沉积时间的方法受到处理可能与矿石有关的矿物的技术和/或不保留矿化年龄的技术的限制。 例如，一种测年技术涉及使用Ar（氩），一种天然状态的气体，尽管Ar可以在岩石和矿物中发现和测量，但这不是一个适合该元素的位置。 相比之下，Re和Os都是喜欢硫化物的，并且天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。 这项研究将侧重于与两个年轻的岩浆系统，托管巨大的钼和铜矿床，经典的亨德森钼存款在科罗拉多州和洛杉矶Pelambres铜钼存款在智利有关的成矿年龄。

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.