Re-Os Studies of Ore Deposits

形成大型存款的热液活动的持续时间和成矿元素的来源是成矿作用研究的中心问题。 一个特殊的同位素方法，可以在解决这两个问题是有用的Re-Os系统，因为Os，作为亲铁元素，是集中在硫化物。 因此，用Re-Os同位素体系代替伴生硅酸盐直接定年硫化物在理论上是可能的，用Os同位素比值示踪矿床中壳幔源的相对重要性也是可能的。 在用铼-锇同位素测定矿床年龄方面，P.I.s已经取得了很大的进展，在此P.I.s建议：（1）继续他们对铼-锇同位素结晶后行为的研究。 (2)用等时线法确定其他硫化物对测定贱金属斑岩系统的有效性。 (3)用铼-锇同位素限制贱金属斑岩矿床中金属的来源，这些矿床代表地壳内亲铜元素的积累。 这一研究结果将为研究会聚边缘贱金属斑岩成矿作用和壳幔相互作用提供新的思路。

9628150 Ruiz The duration of hydrothermal activity capable of forming a large ore deposit and the source of ore-forming elements are central questions in the study of metallogenesis. S particular isotopic method that can be useful in addressing these two questions is the Re-Os system because Os, as a siderophile element, is concentrated in sulfides. thus it is theoretically possible to directly date sulfides instead of associated silicates by the Re-Os isotopic system and it is also possible to use the isotopic ratio of Os to trace the relative importance of crustal and mantle sources in ore deposits. the P.I.s have already made great progress in using molybdenite to date ore deposits with Re-Os isotopes and here the P.I.s propose to: (1) Continue their investigations of the post-crystallization behavior of molybdenite. (2) Determine the usefulness of other sulfides to date base metal porphyry systems by the isochron method. (3) Constrain, using Re-Os isotopes, the source of metals in base metal porphyry deposits, which represent accumulations of chalcophile elements within the earth's crust. The results of this study will provide new insights into base metal porphyry metallogenesis and the crust mantle interactions in convergent margins.