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

南非含金刚石沉积物碎屑锆石的 U-Pb 年代学、Hf 同位素和微量元素地球化学

• 批准号: 5427449
• 负责人: Dr. Yann Lahaye
• 金额: --
• 依托单位: Abteilung Petrologie und Geochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2004
• 资助国家: 德国
• 起止时间: 2003-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5427449?language=en
• 关键词: Pb; Geochronologie; Hf; Isotopie; und

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.

钻石开采于橙子河和瓦尔河水系沿着的古老河流阶地、纳米比亚西南海岸沿着的海滩砾石以及近海海洋矿床。这些钻石来自原生矿床（大多数是卡普瓦尔克拉通内的白垩纪金伯利岩，但也指出了其他来源），并通过橙子河和瓦尔河系统穿越南非运往纳米比亚海岸。大量的锆石与钻石一起运输，是钻石开采过程的副产品。显微分析的最新进展表明，激光烧蚀电感耦合等离子体质谱使用单和多个收集器可以提供快速和准确的地球化学和同位素信息的重矿物，如锆石。LA-ICP-MS锆石年代学研究表明，LA-ICP-MS是研究沉积物源区的有力工具。因此，微量元素组合物，Hf同位素特征和U-Pb系统的LA-ICP-MS和LA-MC-ICP-MS，从纳米比亚/南非锆石的组合使用，应提供新的约束南部非洲的性质和生长历史，以及在造山旋回期间和之后形成的火成岩和变质岩的演化。