Metasomatic Processes and Platinum Group Element Deposits in Layered Intrusions

大型层状基性杂岩是重要的，因为它们包含火成岩岩石学基本过程的证据，因为其中一些含有各种金属的经济矿床，包括铂族元素（PGEs）。本项目解决的基本问题是，后积云岩浆过程，特别是交代作用，在富pge层位形成中的作用是什么。为了调查这个问题，将进行两个相关的研究。第一，详细研究了Bushveld杂岩东北部Atok地区Merensky礁及其邻近岩石中辉石等主要相的微量元素含量。第二项研究涉及大堤富含pge的地层。该层位被称为MSZ，显示出一种独特的地球化学地层剖面，在地层中发现的Ni， Cu， S和Au的最大浓度比Pt， Pd和其他pge的最大浓度高约15至30 cm。研究了辉石中亲铜元素的谱图与不相容元素的含量之间的关系，并用离子探针测定。Se/S、As/S和Te/S比值有助于区分硫化物主要是累积富集还是交代富集。

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.