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Rb-Sr and Sm-Nd isotope geochemistry and chronology of cherts from the Onverwacht Group (3.5 AE), South AfricaAn Rb-Sr and Sm-Nd isotopic analysis of Archean chert samples from the Onverwacht Group, South Africa is presented, showing the same characteristic Rb and Sr concentrations as Phanerozoic cherts, with a very large range of Rb-87/Sr-86 ratios. A good correlation line in the Rb-87 to Sr-87 evolution diagram, corresponding to an age of about 2119 My and an initial Sr-87/Sr-86 ratio of about 0.72246, is derived which may be interpreted as reflecting the age of rehomogenization of the Sr in the protolith and the recrystallization of these cherts due to circulating hydrothermal fluids during regional metamorphism about 1.4 AE after deposition of the Onverwacht Group. The Sm-Nd systematics reflect an ancient source age of about 3.5 AE.
Document ID
19870053350
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1016/0016-7037(87)90109-8
Authors
Weis, D. (California Inst. of Tech. Pasadena, CA, United States)
Wasserburg, G. J. (California Institute of Technology Pasadena, United States)
Date Acquired
August 13, 2013
Publication Date
April 1, 1987
Publication Information
Publication: Geochimica et Cosmochimica Acta
Volume: 51
ISSN: 0016-7037
Subject Category
Geophysics
Accession Number
87A40624
Funding Number(s)
CONTRACT_GRANT: NAG9-43
CONTRACT_GRANT: NSF EAR-83-12882
Distribution Limits
Public
Copyright
Other

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