Structural, geophysical and geochemical characterisation of a Mesoarchean paleosuture zone, Barberton Greenstone Belt, South Africa

Images of the electrical conductivity of the subsurface below the Barberton Greenstone Belt (BGB) reveal two electrically conductive zones that extend to a depth of at least 5km. These high conductivity zones correlate well with regional shear zones geologically mapped at surface. The serpentinised Stolzburg Layered Ultramatic Body (SLUB) occurs along one of these shear zones, the Saddleback-Inyoka Shear Zone (SISZ). In an attempt to identify the conductive rocks or phases responsible for the observed electrical conductivity anomalies, impedance spectroscopy measurements on samples collected from regional rock types and shear zone related lithologies were undertaken, and show that the rocks from the BGB are generally very resistive. Sulphide rich greenschists and greywackes collected at depth from the northern extension of the SISZ have elevated conductivities, but are not comparable to the anomalies observed in inversions of the magnetotelluric data. Magnetite veins from the SLUB were the only materials that had electrical resistivities low enough to be comparable with the conductivity anomalies. In order to better understand the structural evolution of the western extent of the greenstone belt, a field investigation was undertaken in the SLUB.

Grantor dc:publisher.institution

Department of Geological Sciences

Year dc:date.issued

2012

Author dc:creator

• MacLennan, Scott Angus

Advisors dc:contributor.advisor

• De Wit, Maarten
• Weckmann, Ute
• Spangenberg, Erik
• Ritter, Oliver

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/10949

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/10949