Halogen Geochemistry and Cl Isotopes of the Stillwater and Bushveld Complexes

9705507南非布什维尔德杂岩的博德罗是少数几个含有大量含卤素矿物异常富含氯的地层段的侵入岩之一。这项研究有三个主要目的：1)由于布什维尔德杂岩的含铂麦伦斯基暗礁及其伴生的边缘岩床的卤素地球化学仍鲜为人知，我们建议对这些岩石进行更全面的采样，以利用电子探针研究含卤素矿物的组成。伴生的岩床特别令人感兴趣，因为它们的成分可能保存了布什维尔德岩浆原始卤素浓度的证据(S)。2)我们建议对布什维尔德杂岩、围岩及其伴生的岩床和岩脉的稳定氯同位素特征与已有的锶、氧、氢同位素趋势数据进行分析和比较。结合岩石学和野外证据，这些数据应该允许我们约束认为高氯是由于地幔熔融事件、污染或来自围岩的变质流体渗入的模型。3)我们将研究PGE(铂族元素)与卤素之间的可能相关性。从积云间液体中演化出的富氯流体可能是铂族元素(PGE)的一种潜在的有用的传输机制。我们将确定背景前列腺素E(用电感耦合等离子体质谱分析)、S、贱金属和氯的相关程度。这些数据将与岩石学和地球化学研究相结合，并辅之以脱气、PGE传输和矿物-液体-流体平衡的定量模拟，以测试PGE传输和浓缩的模型。

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.