Metasomatic Processes and Platinum Group Element Deposits in Layered Intrusions

层状岩体中的交代过程和铂族元素沉积

• 批准号: 9316129
• 负责人: Edmond Mathez
• 金额: $ 10.42万
• 依托单位: American Museum Natural History
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-02-01 至 1998-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9316129&HistoricalAwards=false
• 关键词: Metasomatic; Processes; Platinum; Group; Element

9316129 Mathez The large layered mafic complexes are important because they contain evidence for fundamental processes in igneous petrology and because several contain economic deposits of various metals, including the platinum group elements (PGEs). The essential question addressed by this project is what is the role of post-cumulus, magmatic processes, in particular metasomatism, in the formation of PGE-rich horizons. In order to investigate this question, two related studies will be conducted. The first involves a detailed study of trace element contents of pyroxene and other major phases of the Merensky reef and adjacent rocks in the Atok area, northeast Bushveld Complex. A second study involves the PGE-rich horizon of the Great Dyke. The horizon, which is known as the MSZ, exhibits a characteristic geochemical stratigraphic profile whereby the maximum concentrations of Ni, Cu, S and Au are found approximately 15 to 30 cm higher in the stratigraphy than the maximum concentrations of Pt, Pd and the other PGEs. A relationship will be sought between the profiles for the chalcophile elements and incompatible element contents of pyroxene, which again will be determined by ion probe. Se/S, As/S and Te/S ratios may help to distinguish whether the sulfides were concentrated by mainly cumulate or metasomatic processes.

9316129 Mathez大型层状镁铁质杂岩很重要，因为它们包含火成岩岩石学基本过程的证据，而且其中几个包含各种金属的经济矿藏，包括铂族元素(PCE)。该项目所涉及的基本问题是，后积云、岩浆作用，特别是交代作用，在形成富含PGe的地层层中起了什么作用。为了研究这一问题，将进行两个相关的研究。第一部分是对东北布什维尔德杂岩Atok地区Merensky礁和围岩中辉石等主要相的微量元素含量进行了详细研究。第二项研究涉及大堤富含前列腺素E的地平线。地层中镍、铜、S和金的最大浓度比铂、钯和其他铂族元素的最大浓度高约15~30厘米。将寻找亲硫元素的分布与辉石的不相容元素含量之间的关系，这也将通过离子探针来确定。Se/S、As/S和Te/S比值有助于区分硫化物是以堆积作用为主还是以交代作用为主。