Re-Os Isotopic Systematics Accompanying the Conversion of Organic-Rich, Pelitic Country Rocks to Hornfels, Magma Contamination and Sulfide Ore-Genesis, Duluth Complex

富含有机物的泥质乡村岩石转化为角岩的铼锇同位素系统学、岩浆污染和硫化物成矿，德卢斯杂岩

• 批准号: 9814204
• 负责人: Edward Ripley
• 金额: $ 11.3万
• 依托单位: Indiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9814204&HistoricalAwards=false
• 关键词: Re; Os; Isotopic; Systematics; Accompanying

9814204RipleyBecause of the enrichment of Re relative to Os in mantle-derived, basaltic partial melts, and the high Re/Os ratio of crustal rocks, the Re/Os isotopic system has proven to be a sensitive tracer in the evaluation of dynamic interaction processes between crust and mantle-derived mafic magmas. In the assessment of country rock contamination the application of the Re-Os isotopic system as a petrologic tracer is dependent upon the proper evaluation of open- or closed-system behavior in the contaminant rock, and immobility of Re and Os after crystallization of the igneous rock or sulfide-rich ore material. This project will evaluate the distribution and isotopic characteristics of Re and Os in organic-rich sedimentary rocks, changes in isotopic characteristics during contact metamorphism and conversion of these rocks to hornfels, and isotopic variation found in sulfide-bearing igneous rocks produced as a result of assimilation of country rocks or a released fluid phase. The geologic setting of the Duluth Complex and Proterozoic country rocks presents an excellent opportunity to trace the evolution of the Re-Os system through the processes of contact metamorphism and dehydration, and assimilation of country rocks by mafic magma. Both crustally-contaminated and uncontaminated gabbroic and troctolitic rocks are present in the area of the Babbitt Cu-Ni deposit, and systematic Re-Os analyses will permit an in-depth evaluation of the causes of isotopic variability that may originate as a result of metamorphic and hydrothermal processes in the country rocks, and magmatic processes related to changes in the ratio of silicate magma to sulfide magma.

9814204Ripley由于在地幔玄武岩部分熔体中Re相对于Os富集，并且地壳岩石的Re/Os比率较高，Re/Os同位素系统已被证明是评估之间动态相互作用过程的敏感示踪剂。地壳和地幔衍生的镁铁质岩浆。 在围岩污染评估中，Re-Os 同位素系统作为岩石示踪剂的应用取决于对污染岩石中开放或封闭系统行为的正确评估，以及火成岩结晶后 Re 和 Os 的固定性岩石或富含硫化物的矿石材料。 该项目将评估富含有机物沉积岩中铼和锇的分布和同位素特征、接触变质作用和这些岩石向角岩转化过程中同位素特征的变化，以及由于沉积岩中的硫化物而产生的含硫化物火成岩中发现的同位素变化。围岩的同化或释放的流体相。 德卢斯杂岩和元古代围岩的地质背景提供了一个极好的机会，可以通过接触变质作用和脱水过程以及镁铁质岩浆对围岩的同化来追踪铼锇系统的演化。 巴氏合金铜镍矿床区域中存在地壳污染和未污染的辉长岩和滑石，系统的铼锇分析将有助于深入评估可能源于变质作用的同位素变异的原因。围岩中的热液过程，以及与硅酸盐岩浆与硫化物岩浆比例变化有关的岩浆过程。