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Sulphidation in the Witwatersrand Goldfields: evidence from the Middelvlei Reef

Published online by Cambridge University Press:  05 July 2018

Russell E. Myers ,
Taihe Zhou  and
G. Neil Phillips
Russell E. Myers
Affiliation:
National Key Centre in Economic Geology, Geology Department, James Cook University, Townsville, Australia Q4811
Taihe Zhou
Affiliation:
National Key Centre in Economic Geology, Geology Department, James Cook University, Townsville, Australia Q4811
G. Neil Phillips
Affiliation:
National Key Centre in Economic Geology, Geology Department, James Cook University, Townsville, Australia Q4811
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Abstract

There is extensive textural evidence for sulphidation in the Middelvlei Reef of the Carletonville Goldfield, South Africa. Secondary iron sulphides have replaced sand- and pebble-sized elasts in conglomerate, as well as matrix material in both conglomerate and quartzite. Within the Middelvlei Reef there is a close correspondence between the intensity of sulphidation and areas of greater modal muscovite, and there is less sulphidation where chloritoid dominates. Both pyrite and minor pyrrhotite are widespread. The timing of the sulphidation appears to be post-depositional but the relative importance of diagenetic and syn-metamorphic processes cannot be determined using textural criteria. The absence of retrograde effects suggests that sulphidation occurred prior to or during peak metamorphism. The distribution and intensity of sulphidation and phyllosilicate alteration indicate that these processes may be more significant in the Witwatersrand than has generally been thought. These processes should be considered in all future genetic models.

Keywords

sulphidationgoldfieldsWitwatersrandSouth Africa
Type
Research Article
Information
Mineralogical Magazine , Volume 57 , Issue 388 , September 1993 , pp. 395 - 405
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1993

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