Recycling of Paleoplacer Gold through Mechanical and Postdepositional Mobilization in the Neoarchean Black Reef Formation, South Africa
AuthorNwaila, G. T.
Manzi, M. S. D.
Maselela, H. K.
Durrheim, R. J.
Rose, D. H.
Nwaila, P. C.
Bam, L. C.
AffiliationUniv Arizona, Dept Geosci
MetadataShow full item record
PublisherUNIV CHICAGO PRESS
CitationG. T. Nwaila, M. S. D. Manzi, J. Kirk, H. K. Maselela, R. J. Durrheim, D. H. Rose, P. C. Nwaila, L. C. Bam, and T. Khumalo, "Recycling of Paleoplacer Gold through Mechanical and Postdepositional Mobilization in the Neoarchean Black Reef Formation, South Africa," The Journal of Geology 127, no. 2 (March 2019): 137-166. https://doi.org/10.1086/701678
JournalJOURNAL OF GEOLOGY
Rights© 2019 by The University of Chicago. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractThe source of gold in the ca. 2.66 Ga Black Reef Formation (BRF) has been investigated and constrained through petrographic, mineralogical, geochemical, and high-resolution three-dimensional reflection seismic data combined with drill core and underground geological mapping. The BRF is a strong seismic marker and consists of carbonaceous shale, quartz arenite, and conglomerate. Gold grade in the BRF is primarily controlled by the nature of the host conglomerates. Most of the gold in the BRF conglomerate occurs in native form, and its morphology is highly heterogeneous. Gold was initially introduced through mechanical recycling of underlying Witwatersrand reefs, followed by short-range (millimeter- to centimeter-scale) postdepositional alteration/remobilization associated with the Bushveld Complex and the Vredefort meteorite impact. Although the BRF was subjected to high postdepositional fluid circulation facilitated by high fracture density, the volume of dissolved gold was probably too small to form a large gold deposit, except in areas around the Black Reef/Witwatersrand reefs subcrop positions. Findings from this study demonstrate the importance of both sedimentological controls and impact-related structures in the formation of paleoplacer gold deposits during Neoarchean times.
Note12 month embargo; published online: 28 January 2019
VersionFinal published version
SponsorsCIMERA (Centre of Excellence for Integrated Mineral and Energy Resource Analysis); National Research Foundation (South Africa); Sibanye Stillwater; Schlumburger