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A Major Archean, Gold- and Crust-Forming Event in the Kaapvaal Craton, South Africa

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Science  13 Sep 2002:
Vol. 297, Issue 5588, pp. 1856-1858
DOI: 10.1126/science.1075270

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Abstract

The 2.89- to 2.76-gigayear-old conglomerates of the Central Rand Group of South Africa host an immense concentration of gold. The gold and rounded pyrites from the conglomerates yield a rhenium-osmium isochron age of 3.03 ± 0.02 gigayears and an initial 187Os/188Os ratio of 0.1079 ± 0.0001. This age is older than that of the conglomerates. Thus, the gold is detrital and was not deposited by later hydrothermal fluids. This Middle Archean gold mineralization event corresponds to a period of rapid crustal growth in which much of the Kaapvaal craton was formed and is evidence for a significant noble metal flux from the mantle.

  • * To whom correspondence should be addressed. E-mail: jkirk{at}geo.arizona.edu

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