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

钻石是从沿着奥兰治河和瓦尔河系统的古老河流梯田中开采出来的，从纳米比亚西南海岸的海滩砾石中开采出来的，还有近海的海洋沉积物。这些钻石起源于原生矿床（主要是Kaapvaal克拉通内的白垩纪金伯利岩，尽管也有其他来源），并通过奥兰治河和瓦尔河系统穿越南非到达纳米比亚海岸。与钻石一起运输的大量锆石是钻石开采过程的副产品。微量分析的最新进展表明，使用单收集器和多收集器的激光烧蚀电感耦合等离子体质谱法可以快速准确地提供锆石等重矿物的地球化学和同位素信息。利用LA-ICP-MS对锆石进行的年代学研究表明，它是沉积物源研究的有力工具。因此，结合LA-ICP-MS和LA-MC-ICP-MS对纳米比亚/南非锆石的微量元素组成、Hf同位素特征和u - pb分系统的研究，将为研究南部非洲的性质和生长历史，以及造山旋回期间和之后形成的火成岩和变质岩的演化提供新的约束。

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.