Understanding the crust-mantle transition from fast-spreading mid-ocean ridges: experiments and analytical studies using ICDP OmanDP drill core samples

了解快速扩张的大洋中脊的壳幔转变：使用 ICDP OmanDP 钻芯样本进行实验和分析研究

• 批准号: 439183043
• 负责人: Dr. Carl-Dieter Garbe-Schönberg
• 金额: --
• 依托单位: Institut für Mineralogie
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/439183043?language=en
• 关键词: Understanding; crust; mantle; transition; fast

In winter 2017/18, the ICDP drilling initiative "Oman Drilling Project" (OmanDP) successfully penetrated the paleo-crust-mantle transition of the Oman ophiolite, which is regarded as the world’s largest, best-exposed, and most-studied section of subaerially exposed oceanic lithosphere. The cores are 400 m (CM1) and 300 m (CM2) long and were recovered with a nearly 100 % success rate, making them a uniquely valuable resource for petrographical, petrological, and geochemical study and ensuring access to coherent sections throughout the enigmatic transition between the uppermost mantle and the lowermost crust of fast-spreading ridge systems. The drilled transects through the crust-mantle transition of the Oman paleo-crust, provide coherent long sections of the lowermost layered gabbros, massive dunites, troctolites, and wehrlites without any gaps, and can be regarded as a Rosetta Stone for understanding the magmatic processes and the mode of deep crustal accretion, in a depth window that was not accessible in recent oceans so far. The proposed project focuses on several scientific targets following two different methodological approaches: (1) In an experimental study we aim to simulate equilibrium and fractional crystallization in a parental MORB-type system relevant for a setting of initiation of a subduction zone at the transition between "dry" (like East Pacific Rise) and "wet" conditions (Izu-Bonin-Mariana arc-type crust). In a subproject we aim to quantify the trace element distribution between spinel/chromite and MORB melt. (2) The second approach focus on petrological and geochemical investigations on the rocks from the CM1 and CM2 drill cores in order to clarify the mechanism of massive dunite formation in the crust-mantle transition, and establish the exact mode of differentiation/fractionation within the lowermost crust. The results of both complementary approaches will provide a basis for a deep understanding of the magmatic processes at the base of fast-spreading crust in an environment of initial subduction, and will provide fundamental knowledge about the geodynamics of accretion of fast-spreading oceanic crust.

在2017/18冬季，ICDP钻探计划“阿曼钻探项目”（OMANDP）成功地渗透了阿曼蛇绿岩的古 - 壳竖琴过渡，该过渡被认为是世界上最大，最受欢迎，最受欢迎，最受欢迎的部分较大的较大型号的大洋。核心为400 m（CM1）和300 m（CM2），并以接近100％的成功率回收，使它们成为岩石学，岩石学和地球化学研究的独特宝贵资源，并确保在整个范围内的杂物转换中，可访问高度较低的地幔和较低的甲壳机之间，并成为快速的系统之间的混乱。 The drilled transects through the crust-mantle transition of the Oman paleo-crust, provide coherent long sections of the lowermost layered gabbros, massive dunites, troctolites, and wehrlites without any gaps, and can be considered as a Rosetta Stone for understanding the Magmatic processes and the mode of deep crustal accretion, in a depth window that was not accessible in recent oceans so far. The proposed project focuses on several scientific targets following two different methodological approaches: (1) In an experimental study we aim to simulate equivalent and fractional crystallization in a parental MORB-type system relevant for a setting of initiation of a subduction zone at the transition between "dry" (like East Pacific Rise) and "wet" conditions (Izu-Bonin-Mariana arc-type crust).在主题项目中，我们旨在量化尖晶石/铬铁矿和MORB熔体之间的微量元素分布。 （2）第二种方法着重于对CM1和CM2钻芯的岩石的岩石学和地球化学研究，以阐明在地壳 - 甲壳虫过渡中大规模邓纳特形成的机制，并在最低的地壳内建立分化/分级的确切模式。两种完全方法的结果都将为对最初俯冲环境中快速膨胀的外壳底部的岩浆过程提供深入了解，并将提供有关快速膨胀海洋壳的胚芽的地球动力学的基本知识。