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.

建议对来自大西洋东北部外沃林高原海洋钻探计划第 104 段 642E 孔的钻芯进行重新取样和重新研究。这些岩心记录了可追溯到大西洋东北部早期裂谷阶段的岩浆事件。孔的底部由“下部系列”组成，由基性岩脉和玄武质安山岩流、过铝质堇青石英安岩、流纹质凝灰岩和互层火山碎屑岩单元组成。该下层系位于厚厚的过渡型洋中脊拉斑玄武岩“上层系”之下。下层系组合清楚地表明地幔熔体与地壳物质的相互作用和/或底侵作用下的显着地壳熔融。该剖面特别适合研究地幔岩浆与地壳的污染，因为可以明确地定义地壳成分的化学和同位素特征。迄今为止，针对 Hole 642E 火山岩的研究相当有限。此外，自最初的研究以来，岩石成因概念以及同位素和微量元素分析的分析设施有了一些新的发展。新研究旨在更好地确定这些地下喷发火山的喷发模式和沉积环境，以揭示喷发和岩浆动力学。将通过 ICP-MS 研究大量新样品的痕量元素组成，并通过 TIMS 和多接收器 ICP-MS 研究 Sr,Nd,Hf,Pb 同位素组成，以期确定地幔地壳的范围和过程相互作用。这反过来将能够更好地限制（原始）冰岛地幔柱中产生的地幔熔体在空间和时间上的内在地球化学异质性。