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New evidence for the early onset of supergene alteration along the Kalahari unconformity

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Vafeas, NA, Blignaut, LC, Viljoen, KS and Meffre, S ORCID: 0000-0003-2741-6076 2018 , 'New evidence for the early onset of supergene alteration along the Kalahari unconformity' , South African Journal of Geology, vol. 121, no. 2 , pp. 157-170 , doi: 10.25131/sajg.121.0012.

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Abstract

The manganese ore of the Hotazel Formation in the Kalahari Manganese Field, which has been thrust along the Blackridge thrust fault, has been subjected to various degrees of pre-thrusting hydrothermal and post-thrusting supergene alteration. Coarse-grained apatite, which appears to be formed under supergene conditions on textural grounds, is present in the thrusted manganese ore in previously unrecorded abundances. U-Pb dating of this apatite within the thrusted manganese ore has placed the onset of chemical weathering of the succession at a 77 ± 7.5 Ma, approximately 35 million years earlier than previously thought for the area. This implies that erosion along the Post-African I land surface, as well as the effects of supergene alteration in the Kalahari Manganese Field must have commenced within the late Cretaceous Period, subsequent to earlier erosion along the African land surface.

Item Type: Article
Authors/Creators:Vafeas, NA and Blignaut, LC and Viljoen, KS and Meffre, S
Keywords: manganese, metal ores, Upper Cretaceous, Cretaceous, Africa, manganese ores, metasomatism, South Africa, Southern Africa, U/Pb, absolute age, Mesozoic mineral deposits, genesis, Northern Cape Province, South Africa
Journal or Publication Title: South African Journal of Geology
Publisher: Geological Society of South Africa, Geologiese Vereniging van Suid-Afrika
ISSN: 1012-0750
DOI / ID Number: 10.25131/sajg.121.0012
Copyright Information:

Copyright 2018 Geological Society of South Africa

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