US- South Africa Planning Visit: Developing a Project on the Genesis of the Platreef Mineralized Zone

这项计划访问奖将使PI、两名同事和一名研究生能够与来自威特沃特斯兰德大学和PotgietersRust Platinum Limited(PPL)的几名南非科学家合作，在南非开展实地工作，并敲定合作研究项目的计划。该项目的目的是了解铂礁的起源，这是世界上最大、矿化程度最高的火成岩侵入体布什维尔德杂岩中最重要的铂矿床。Bushveld杂岩的海侵基底横跨变质岩、变质碳酸盐和基底花岗岩，不仅为研究这些寄主岩石单元对变质和熔融的不同响应提供了机会，也为研究与不同寄主岩石污染有关的平台礁成矿作用的差异提供了机会。我们推测，Platreef中的污染是光环岩石部分熔融的结果，逃逸的熔体是主要污染物。然而，熔体是来自基底花岗岩还是来自变质花岗岩尚不清楚，尽管之前已经提出了基底花岗岩的来源。除了来自日冕岩石的前进性污染外，还有涉及挥发性相的逆行重新分配问题，这一点还没有得到充分的了解。该项目将有助于支持国际研究合作的发展，并将为研究生提供国际研究经验。

This planning visit award will enable the PI, two colleagues, and a graduate student to work with several South African scientists from the University of the Witwatersrand and from Potgietersrust Platinums Limited (PPL), conducting field work in South Africa and finalizing plans for a collaborative research project. The aim of the project is to understand the origin of the Platreef, which is the most significant platinum deposit in the Bushveld Complex, the world.s largest and most mineralized igneous intrusion. The transgressive base of the Bushveld Complex crosses metapelites, metacarbonates and basement granites, and thus affords an opportunity to investigate not only the different response of these host rock units to metamorphism and melting, but also differences in Platreef mineralization related to contamination from the different host rocks. We postulate that the contamination in the Platreef is a consequence of partial melting in the aureole rocks, and that the fugitive melt was the principal contaminant. However, whether the melt is derived from the basement granites or the metapelites is unknown, although a basement granite source has been previously suggested.In addition to prograde contamination from aureole rocks, there is the issue of retrograde redistribution involving a volatile phase, which is not adequately understood. This project will help support the development of an international research collaboration and will provide international research experience for the graduate student.