Isotopen- und Spurenelementuntersuchungen an Basalten von Mittelozeanischen Rücken, der Cook-Austral Inselkette, sowie von Tristan da Cunha und Gough

对库克-南链、圣赫勒拿、特里斯坦-达库尼亚和高夫玄武岩以及大洋中脊玄武岩(MORB)进行了详细的地球化学研究(锶、钕、铅、氢同位素和常量及微量元素测定)。库克-奥斯特拉尔链玄武岩覆盖了大洋岛玄武岩(OIB)同位素序列的三分之二，范围从类HIMU(高铅同位素比值玄武岩的首字母缩写)到EM类玄武岩(高锶低Nd和铅同位素比值玄武岩的首字母缩写)。类HIMU玄武岩分为两种不同类型。一个与圣赫勒拿玄武岩同位素相似，另一个与富集型MORB相似。对库克南玄武岩和MORB的详细调查将表明这两个特征是否具有共同的基因起源。此外，还将调查回收沉积物在库克-奥索拉尔玄武岩、高夫玄武岩和特里斯坦-达库尼亚玄武岩地幔来源中的潜在作用。只有将主量元素和痕量元素与同位素数据相结合，才能完整地描述地幔来源，但也可以提供有关熔融原因、熔体提取机制和非均质地幔物质规模的信息。这些信息对于根据全球地幔结构和演化模型解释地球化学数据是必不可少的。

A detailed geochemical study of basalts from the Cook-Austral chain, St. Helena, Tristan da Cunha and Gough as well as mid ocean ridge basalts (MORB) is proposed (Sr, Nd, Pb, and Hf isotope and major and trace element measurements). Basalts from the Cook-Austral chain cover two thirds of the ocean island basalt (OIB) isotopic array and range from HIMU-like (acronym for basalts with high Pb isotope ratios) to EM-like basalts (acronym for basalts with high Sr, low Nd and Pb isotope ratios). HIMU-like basalts group into two different types. One is isotopically similar to St. Helena basalts, the other is similar to enriched MORB. A detailed investigation of CookAustral basalts and MORB will show whether these two signatures have a common genetic origin. In addition, the potential role of recycled sediment in the mantle source of the Cook-Austral, Gough and Tristan da Cunha basalts will be investigated. Only combining major and trace element with isotopic data allows complete characterization of mantle sources, but can also provide information about the cause of melting, melt extraction mechanisms and the scale of the heterogeneous mantle materials. This information is essential for interpreting geochemical data in terms of global mantle structure and evolution models.