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Published March 2009 | public
Journal Article

Paleomagnetism of a Neoarchean-Paleoproterozoic carbonate ramp and carbonate platform succession (Transvaal Supergroup) from surface outcrop and drill core, Griqualand West region, South Africa


Detailed paleomagnetic study across the Archean-Paleoproterozoic boundary interval preserved in the Ghaap Group, Transvaal Supergroup, of the Kaapvaal craton reveals a complex series of viscous and thermo-chemical magnetic overprints. Despite this complex history, a potential primary single-polarity remanence direction was revealed at high-temperature demagnetization steps in about 10% of orientated drill core samples only. This component (declination = 132°, inclination = 69°) was not identified in any of the outcrop sites. Overprint directions include a present geomagnetic field remanence and a very well developed thermo-chemical overprint (declination = 359°, inclination = 54°), which is believed to be associated with a ~2.0 Ga regional thermal event and the development of extensive epigenetic Pb–Zn deposits. At higher levels of demagnetization, two shallow west-directed components appear to be related to the extrusion of the Ongeluk Formation lava at 2.22 Ga (declination = 268°, inclination = −20°; eastern parts of the studied region) and to the post-1.92 Ga Kheis orogeny (declination = 272°, inclination = 16°; exclusive to the western margin of the study area), respectively.

Additional Information

© 2008 Elsevier B.V. Received 24 December 2007. Received in revised form 12 May 2008. Accepted 23 October 2008. Available online 25 December 2008. We would like to thank the reviewers as well as Chris Rowan, whose comments and suggestions have improved the manuscript considerably. We thank Alec Birch, former geologist at Pering Mine, who oversaw drilling of the Agouron drill cores. We also thank Francis Macdonald for his assistance during fieldwork. The management of BHP-Billiton is acknowledgements for permission to conduct parts of this investigation at Pering Mine, andwe are grateful to the various owners, who allowed us access to their land in the course of this study.

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