Halogen Geochemistry and Cl Isotopes of the Stillwater and Bushveld Complexes

Boudreau南非的Bushveld杂岩是为数不多的具有广泛地层剖面的侵入岩之一，其中含卤素矿物异常富含氯。本研究有三个主要目的：1)由于对Bushveld杂岩中含铂的Merensky礁及其伴生边缘岩的卤素地球化学知之甚少，我们建议对这些岩石进行更完整的采样，利用电子探针研究含卤素矿物的组成。相关的技能是特别感兴趣的，因为它们的成分可能保存了原始的布什维尔德岩浆的卤素浓度的证据。2)我们建议分析和比较Bushveld杂岩、围岩和伴生岩脉的Sr、O和H同位素趋势与现有资料的稳定Cl同位素特征。结合岩石学和野外证据，这些数据应该允许我们限制模型，即高Cl是由于地幔流动事件、污染或变质流体从乡村岩石渗透造成的。3)研究铂族元素（铂族元素）与卤素之间可能存在的相关性。积云间液体中富cl流体的演化可能是铂族元素（PGE）潜在有用的运输机制。我们将确定背景PGE（通过ICP-MS分析）、S、贱金属和Cl的相关程度。这些数据将与岩石学和地球化学研究相结合，并与脱气、PGE输运和矿物-液-流平衡的定量建模相结合，以测试PGE输运和浓度模型。

9705507 Boudreau The Bushveld complex in South Africa is among the few intrusions that contain extensive stratigraphic sections in which halogen-bearing minerals are unusually rich in chlorine. This study has three major objectives: 1) Because halogen geochemistry of the platiniferous Merensky Reef of the Bushveld complex and associated marginal sills are still poorly known, we propose to sample these rocks more completely to investigate the compositions of halogen-bearing minerals using electron microprobe. The associated sills are of particular interest as their compositions may preserve evidence of the original halogen concentrations of Bushveld magma(s). 2) We propose to analyze and compare stable Cl isotopic characteristics with existing data for Sr, O and H isotopic trends for the Bushveld complex, their country rocks and associated contemporaneous sills and dikes. Along with petrographic and field evidence, this data should allow us to constrain models suggesting that high Cl is due to a mantle fluxing event, contamination or metamorphic fluid infiltration from the country rocks. 3) We will investigate possible correlations between PGE (Platinum Group Elements) and halogens. Evolution of Cl-rich fluids from intercumulus liquids could be a potentially useful transport mechanism for the platinum-group elements (PGE). We will determine to what extent of background PGE (to be analyzed by ICP-MS) , S , base metals and Cl are correlated. These data will be combined with petrographic and geochemical studies, augmented with quantitative modeling of degassing, PGE transport and mineral-liquid-fluid equilibria, to test models of PGE transport and concentration.