Re-Os Studies of Ore Deposits

9628150鲁伊斯，能够形成大型矿床的热液活动持续时间和成矿元素的来源是成矿作用研究的中心问题。解决这两个问题的有用的同位素方法是Re-Os体系，因为Os作为一种亲铁元素，集中在硫化物中。因此，理论上可以用Re-Os同位素体系直接测定硫化物的年龄而不是伴生的硅酸盐的年龄，也可以用Os的同位素比值来追踪地壳和地幔来源在矿床中的相对重要性。他们在利用辉钼矿进行Re-Os同位素定年方面已经取得了很大进展，他们建议：(1)继续研究辉钼矿的结晶后行为。(2)用等时线法确定其他硫化物对贱金属斑岩系统测年的有效性。(3)用Re-Os同位素约束贱金属斑岩矿床中金属的来源，这代表着地壳内亲银元素的积累。这一研究结果将为研究会聚边缘的贱金属斑岩成矿作用和壳幔相互作用提供新的认识。

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.