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

Nick A. Vafeas, L. C. Blignaut, K. S. Viljoen and Sebastien Meffre
New evidence for the early onset of supergene alteration along the Kalahari unconformity
South African Journal of Geology (June 2018) 121 (2): 157-170

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 + or - 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.


ISSN: 1012-0750
EISSN: 1996-8590
Serial Title: South African Journal of Geology
Serial Volume: 121
Serial Issue: 2
Title: New evidence for the early onset of supergene alteration along the Kalahari unconformity
Affiliation: University of Johannesburg, Department of Geology, Johannesburg, South Africa
Pages: 157-170
Published: 201806
Text Language: English
Publisher: Bureau for Scientific Publications, Pretoria, South Africa
References: 40
Accession Number: 2018-080142
Categories: Economic geology, geology of ore depositsGeochronology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. cols., 3 tables, geol. sketch maps
S33°00'00" - S24°40'00", E16°25'00" - E25°30'00"
Secondary Affiliation: University of Tasmania, AUS, Australia
Country of Publication: South Africa
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Abstract, Copyright, Geological Society of South Africa. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201844
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