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Accretion of the lower oceanic crust at fast-spreading ridges: a rock drill and near-bottom seafloor survey in support of IODP drilling in Hess Deep.

快速扩张的海脊处下洋地壳的增生：支持赫斯深海 IODP 钻探的凿岩机和近海底调查。

基本信息

批准号：
NE/C509023/1
负责人：
Christopher MacLeod
金额：
$ 42.43万
依托单位：
CARDIFF UNIVERSITY
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2008
资助国家：
英国
起止时间：
2008 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FC509023%2F1
关键词：
Accretion lower oceanic crust fast

项目摘要

Generation of ocean lithosphere by seafloor spreading at mid-ocean ridges is one of the fundamental geological processes operating on Earth. One of the most important yet most intractable problems is to understand how the magma reservoir beneath ridges generates the lower crust, especially at fast spreading rates. Gabbroic rocks from fast-spread lower crust are normally inaccessible; only in the Hess Deep rift valley (E Pacific) is a substantial section known to be exposed. We propose to survey this unique section using a remotely-operated vehicle in order to satisfy site survey requirements for the highly-ranked IODP proposal #551. In addition we plan to conduct our own sampling programme using the British Geological Survey's 'BRIDGE' seabed rock drill to obtain large numbers of short (1 m) orientated cores in transects through the gabbro section. Constraining heat and mass flux from the Earth's mantle to crust and crust to ocean, and testing conflicting models for the functioning of mid-ocean ridge magma chambers, can only be tested by direct observation and sampling. Fully oriented cores are imperative to address many of the outstanding questions and these capabilities of the BRIDGE drill remain unique. This survey will not only augment the IODP proposal but will in its own right also answer many critical questions that IODP operations cannot tackle.

洋中脊海底扩张形成海洋岩石圈是地球上的基本地质过程之一。最重要但最棘手的问题之一是了解洋脊下的岩浆库如何生成下地壳，特别是在快速扩张的情况下。来自快速扩展的下地壳的辉长岩通常是难以接近的;只有在赫斯裂谷（东太平洋）有相当大的一部分已知是暴露的。我们建议使用遥控车辆对这一独特部分进行勘测，以满足高等级IODP提案#551的现场勘测要求。此外，我们还计划使用英国地质调查局的“BRIDGE”海底凿岩机进行我们自己的取样方案，以便在辉长岩剖面中获得大量短（1米）定向岩心。限制从地幔到地壳和地壳到海洋的热量和质量通量，以及测试大洋中脊岩浆房功能的相互矛盾的模型，只能通过直接观察和取样来测试。全定向岩心对于解决许多突出问题至关重要，而BRIDGE钻机的这些功能仍然是独一无二的。这项调查不仅将扩大IODP提案，而且还将回答IODP运营无法解决的许多关键问题。