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

该计划访问奖将使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 Platinums Limited（PPL）的几位南非科学家合作，在南非进行实地考察并最终确定合作研究项目的计划。该项目的目的是了解Platreef的起源，Platreef是世界上最大和矿化最多的火成岩侵入体Bushveld杂岩中最重要的铂存款。Bushveld杂岩的海侵基底穿过变岩、变碳酸盐岩和基底花岗岩，因此提供了一个机会，不仅可以研究这些寄主岩石单元对变质作用和熔融作用的不同反应，还可以研究与不同寄主岩石污染有关的Platreef矿化的差异。 我们假设，在Platreef的污染是部分熔融的光环岩石的后果，和逃亡熔体是主要的污染物。 然而，熔体是来自于基底花岗岩还是来自于变细岩尚不清楚，尽管以前曾有人提出基底花岗岩的来源。除了来自于晕带岩石的岩浆污染外，还有涉及挥发相的逆行再分配问题，这一点还没有得到充分的理解。 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.