Mineralium Deposita

, Volume 48, Issue 2, pp 193–210 | Cite as

Sulfide-associated mineral assemblages in the Bushveld Complex, South Africa: platinum-group element enrichment by vapor refining by chloride–carbonate fluids



The petrology of base metal sulfides and associated accessory minerals in rocks away from economically significant ore zones such as the Merensky Reef of the Bushveld Complex has previously received only scant attention, yet this information is critical in the evaluation of models for the formation of Bushveld-type platinum-group element (PGE) deposits. Trace sulfide minerals, primarily pyrite, pyrrhotite, pentlandite, and chalcopyrite are generally less than 100 microns in size, and occur as disseminated interstitial individual grains, as polyphase assemblages, and less commonly as inclusions in pyroxene, plagioclase, and olivine. Pyrite after pyrrhotite is commonly associated with low temperature greenschist alteration haloes around sulfide grains. Pyrrhotite hosted by Cr- and Ti-poor magnetite (Fe3O4) occurs in several samples from the Marginal to Lower Critical Zones below the platiniferous Merensky Reef. These grains occur with calcite that is in textural equilibrium with the igneous silicate minerals, occur with Cl-rich apatite, and are interpreted as resulting from high temperature sulfur loss during degassing of interstitial liquid. A quantitative model demonstrates how many of the first-order features of the Bushveld ore metal distribution could have developed by vapor refining of the crystal pile by chloride–carbonate-rich fluids during which sulfur and sulfide are continuously recycled, with sulfur moving from the interior of the crystal pile to the top during vapor degassing.


Bushveld Complex Igneous sulfide Platinum-group element deposits Chlorite–carbonate fluids 



This work was completed as part of a Senior Thesis by the senior author at Duke University. We wish to thank Grant Cawthorn of the University of the Witwatersrand, Gordon Chunnett of Anglo Platinum Ltd., and the geologists at the Rustenburg and Marula platinum mines for some of the samples used in this study. This work was improved by the comments of Ed Ripley, Chusi Li, Sarah Penniston-Dorland, Peter Lightfoot, Jacob Hanley, Mike Lesher, and an anonymous reviewer. This work was supported by NSF grant EAR 04-7928.

Supplementary material

126_2012_427_MOESM1_ESM.doc (102 kb)
Table 1 A summary of rock samples and major sulfide mineral assemblages (DOC 102 kb)
126_2012_427_MOESM2_ESM.docx (66 kb)
Table 2 Electron microprobe analysis of sulfide minerals (DOCX 66 kb)
126_2012_427_MOESM3_ESM.docx (12 kb)
Table 3 Microprobe analysis of mixed magnetite-pyrrhotite phase from sample LCZ-105 (DOCX 12.1 kb)
126_2012_427_MOESM4_ESM.docx (14 kb)
Table 4 Average Bushveld noble metal values of various units from the Western Limb of the Bushveld Complex (from Barnes and Maier 2002) and calculated theoretical original footwall source concentrations (DOCX 14 kb)
126_2012_427_MOESM5_ESM.docx (12 kb)
Table 5 Parameters for PALLADIUM model run. All concentrations are in weight fraction, except as noted (DOCX 11.6 kb)


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Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  1. 1.Department of Earth and Ocean SciencesDuke UniversityDurhamUSA
  2. 2.Department of Earth and Planetary ScienceUniversity of CaliforniaBerkeleyUSA

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