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Platinum-group mineral assemblages in the Platreef at the Sandsloot Mine, northern Bushveld Complex, South Africa

Published online by Cambridge University Press:  05 July 2018

D. A. Holwell ,
I. McDonald  and
P. E. B. Armitage
D. A. Holwell*
Affiliation:
School of Earth, Ocean and Planetary Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3YE, UK
I. McDonald
Affiliation:
School of Earth, Ocean and Planetary Sciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3YE, UK
P. E. B. Armitage
Affiliation:
Department of Earth and Environmental Sciences, University of Greenwich, Chatham Maritime ME4 4TB, UK
*
*E-mail: HolwellDA@cf.ac.uk
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Abstract

Platinum group mineral (PGM) assemblages in the Platreef at Sandsloot, northern Bushveld Complex, in a variety of lithologies reveal a complex multi-stage mineralization history. During crystallization of the Platreef pyroxenites, platinum group elements (PGE) and base-metal sulphides (BMS) were distributed thoughout the interstitial liquid forming a telluride-dominant assemblage devoid of PGE sulphides. Redistribution of PGE into the metamorphic footwall by hydrothermal fluids has formed arsenide-, alloy- and antimonide-dominant assemblages, indicating a significant volatile influence during crystallization. Serpentinization of the footwall has produced an antimonide-dominant PGM assemblage. Parts of the igneous reef were subjected to alteration by a late-stage, Fe-rich fluid, producing ultramafic zones where the telluride-dominant assemblage has been recrystallized to an alloy-dominant one, particularly rich in Pt-Fe and Pd-Pb alloys. A thin, small-volume zone of PGE-BMS mineralization along the base of the hangingwall contains a primary PGM assemblage that is locally altered to one dominated by Pt/Pd germanides. This is thought to have formed when the new pulse of Main Zone magma entered the chamber, and scavenged PGE from the underlying Platreef pyroxenites. That each major rock type at Sandsloot contains a distinctive PGM assemblage reflects the importance of syn- and post-emplacement fluid and magmatic processes on the development of Platreef mineralization.

Keywords

PGMBushveld ComplexSouth AfricaSandsloot minePlatreef, PtPdbase-metal sulphides
Type
Research Article
Information
Mineralogical Magazine , Volume 70 , Issue 1 , February 2006 , pp. 83 - 101
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2006

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