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

journal contribution
posted on 2023-05-19, 23:34 authored by Vafeas, NA, Blignaut, LC, Viljoen, KS, Sebastien MeffreSebastien Meffre
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.

Funding

Australian Research Council

AMIRA International Ltd

ARC C of E Industry Partner $ to be allocated

Anglo American Exploration Philippines Inc

AngloGold Ashanti Australia Limited

Australian National University

BHP Billiton Ltd

Barrick (Australia Pacific) PTY Limited

CSIRO Earth Science & Resource Engineering

Mineral Resources Tasmania

Minerals Council of Australia

Newcrest Mining Limited

Newmont Australia Ltd

Oz Minerals Australia Limited

Rio Tinto Exploration

St Barbara Limited

Teck Cominco Limited

University of Melbourne

University of Queensland

Zinifex Australia Ltd

History

Publication title

South African Journal of Geology

Volume

121

Pagination

157-170

ISSN

1012-0750

Department/School

School of Natural Sciences

Publisher

Geological Society of South Africa, Geologiese Vereniging van Suid-Afrika

Place of publication

South Africa

Rights statement

Copyright 2018 Geological Society of South Africa

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the earth sciences