Aspects of the geochemistry of Onverwacht Group lavas from the Barberton Greenstone Belt

The 3540 million year old komatiitic and tholeiitic lavas in the Onverwacht Group (Barberton greenstone belt) crop out in the rugged terrain of the eastern Transvaal lowveld. The results of an investigation into the geochemistry of the lavas, mainly from the three lower Formations of the Onverwacht Group - the Lower Ultramafic Unit (LUU) - are reported. While the lavas generally show excellent textural preservation, their primary phases have usually been reconstituted to greenschist facies mineral assemblages. Although original phenocryst phases are often pseudomorphed, they can still be identified from occasionally preserved relict grains and from the secondary mineral assemblages. In this way all the major phases that occur in the various lava types could be identified. However, before the geochemical data could be used to examine the effects of partial melting and/or crystal fractionation processes in the development of the magma compositions, it was necessary to investigate which elements had been redistributed by later metamorphic and other alteration events that have occurred in the history of the lavas.

Grantor dc:publisher.institution

Department of Geological Sciences

Year dc:date.issued

1980

Author dc:creator

• Smith, Hudson Stuart

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/17780

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/17780