High resolution volcanology and geochemistry of mid ocean ridge segments flanking the 9°40'S melt anomaly and the Ascension hot spot

南纬 9°40 融化异常和阿森松热点两侧洋中脊部分的高分辨率火山学和地球化学

• 批准号: 16112887
• 负责人: Professor Dr. Carsten Münker
• 金额: --
• 依托单位: Institut für Geologie und Mineralogie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2011-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/16112887?language=en
• 关键词: resolution; volcanology; geochemistry; mid; ocean

Mid-ocean ridge volcanism plays a key role in the investigation of melt generation and mantle processes on a global scale. The SPP MARSouth area is particularly suited to investigate the influences of different mantle sources at high resolution, as fertile mantle (9°40'S melt anomaly) and alleged hot spot volcanism (Ascension Island) are both present together with typical depleted MORB. Results from isotope and high-precision HFSE analyses, performed during the first phase of the project, show that previous geodynamic models need to be revised, in particular in the light of new Hf-Nd isotope data. Moreover, our new data for submarine and subaerial volcanism on Ascension demonstrate that distinctive mantle source were tapped that are not related to a rising mantle plume. Based on these promising results we will focus our research during the second phase of the project on erupt ion-scale volcanological and geochemical investigations. The principal aims are to characterize eruption-scale effects of mantle heterogeneities and to unravel the origin of Ascension Island. A second focus will be on the behavior of HFSE (including W) during MORB melting. First result indicate that W-Nb-Ta abundances are little fractionated, which is in marked contrast to experimental predictions. Based on an expanded dataset, we will address this conundrum by trace element modeling.

大海山脊火山主义在全球范围内的融化和地幔过程的投资中起着关键作用。 SPP Marsouth地区特别适合研究高分辨率的不同地幔来源的影响，因为肥沃的地幔（9°40年代的熔体异常），所谓的热点火山（Ascension Island）都与典型的耗尽的病态一起存在。在项目的第一阶段进行的同位素和高精度HFSE分析的结果表明，需要修改以前的地球动力学模型，特别是根据新的HF-ND同位素数据。此外，我们针对升天的海底火山和海底火山的新数据表明，挖掘出独特的地幔源与lising地幔羽无关。基于这些承诺的结果，我们将在项目的第二阶段对爆发的离子尺度火山学和地球化学研究的研究重点。主要目的是表征地幔异质性的爆发尺度影响，并揭示升天岛的起源。第二个重点将放在HFSE（包括W）在MOR融化过程中的行为。第一个结果表明W-NB-TA丰度几乎没有分馏，这与实验预测形成了鲜明对比。基于扩展的数据集，我们将通过跟踪元素建模来解决此难题。