The role of mantle-crust interaction in the early phases of passive margin development: the case of the Voring Plateau, NE Atlantic

地幔-地壳相互作用在被动边缘发育早期阶段的作用：以大西洋东北部沃林高原为例

• 批准号: 5389451
• 负责人: Professor Dr. Lothar Viereck
• 金额: --
• 依托单位: Fysico-Chemical Geology section
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2003
• 资助国家: 德国
• 起止时间: 2002-12-31 至 2007-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5389451?language=en
• 关键词: role; mantle; crust; interaction; early

It is proposed to resample and reinvestigate the drill cores from Hole 642E, Ocean Drilling Program Leg 104, Outer Voring Plateau, NE Atlantic. These cores keep a record of magmatic events dating back to the early rifting phases of the NE Atlantic ocean. The bottom section of the hole is made up of a "Lower Series" consisting of basic dykes and flows of basaltic andesites, peraluminous cordierite-bearing dacites, rhyolitic ignimbrites, and interbedded volcaniclastic units. This Lower Series underlies a thick "Upper Series" of transitional-type mid-ocean ridge tholeiites. The Lower Series assemblage is clearly indicative of interaction of mantle melts with crustal material and/or of significant crustal melting by underplating. The section is particulary suited to study contamination of mantle magmas with crust, because the chemical and isotopic character of the crustal component can be unambiguously defined. The research devoted thus far to the Hole 642E volcanics has been rather limited. Moreover, since the original studies, there have been several new developments in petrogenetic concepts and in analytical facilities for isotopic and trace element analysis. The new studies aim to better define the eruption modes and depositional environment of these subaerially erupted volcanics, in order to shed light on eruption and magma dynamics. A substantial amount of new samples will be studied for trace element composition by ICP-MS and Sr,Nd,Hf,Pb-isotopic composition by TIMS and multi-collector ICP-MS with a view to establish the extent and processes of mantle-crust interaction. This will in turn allow to better constrain the intrinsic geochemical heterogeneity - in space and time - of the mantle melts produced in the (proto-) Iceland mantle plume.

提议从NE Atlantic的外瓦特高原外钻孔计划104孔，海洋钻井程序腿104进行重新采样和重新分配钻头。这些核心保留了岩浆事件的记录，历史可以追溯到NE大西洋的早期裂痕阶段。孔的底部由一个“较低的串联”组成，该序列由玄武岩安山岩的基本堤坝和流量组成，含有木质岩石岩石的dacites，流纹岩Inimbrites和层间火山岩单元组成。这个下部系列是过渡型中山脊tholeiites的厚“上层”。较低的串联组合清楚地表明了地幔融化与地壳材料和/或通过低估的明显地壳熔融的相互作用。该部分特别适合研究地壳岩浆与地壳的污染，因为可以明确定义地壳成分的化学和同位素特征。迄今为止，该研究专门用于642E火山的孔非常有限。此外，自从原始研究以来，岩发生概念以及同位素和痕量元素分析的分析设施中已经有了一些新的发展。这项新研究旨在更好地定义这些次大火山爆发的喷发模式和沉积环境，以阐明喷发和岩浆动力学。通过ICP-MS和SR，ND，HF，PB - 同位素组成，将研究大量的新样品，以通过TIMS和Multi-Crotector ICP-MS进行研究，以确定地幔 - 折叠相互作用的范围和过程。反过来，这将允许更好地限制（原始）冰岛地幔羽流中产生的地幔熔体的内在地球化学异质性。