U-Pb Geochronologie, Hf -Isotopie und Spurenelement-Geochemie an detritischen Zirkonen von Diamant führenden Sedimenten Südafrikas

• Applicant: Dr. Yann Lahaye
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2004 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5427449

Diamonds are mined from ancient river terraces along the Orange- and Vaal River systems and from beach gravels along the southwestern coast of Namibia, as well as offshore marine deposits. These diamonds originated from primary deposits (mostly Cretaceous kimberlites contained within the Kaapvaal craton, although other sources are indicated) and were transported via the Orange- and Vaal River system across South Africa to the Namibian coast. A large number of zircons, transported together with the diamonds, are a by-product of the diamond extraction process. Recent developments in microanalysis have shown that laser ablation inductively coupled plasma mass spectrometry using single and multiple collector can provide fast and accurate geochemical and isotopic information from heavy minerals such as zircon. Previous geochronological studies of zircons by LA-ICP-MS have shown that it is a powerful tool for sedimentary provenance investigations. Therefore the combined use of trace element compositions, Hf isotopic signatures and U-Pb-systematics by LA-ICP-MS and LA-MC-ICP-MS, from the Namibian/South African zircons, should provide new constraints on the nature and growth history of Southern Africa and on the evolution of igneous and metamorphic rocks formed during and subsequent to orogenic cycles.

• DFG Programme: Research Grants
• Participating Persons: Professor Gerhard Peter Brey, Ph.D.; Professor Stefan Weyer, Ph.D.