Structure and petrophysics of oceanic Crust and Lithosphere, Atlantis Massif. Study of cores from IODP Expedition 357 (CLAM)

亚特兰蒂斯地块洋壳和岩石圈的结构和岩石物理学。

基本信息

批准号：
319238429
负责人：
Professor Dr. Jan-Hinrich Behrmann
金额：
--
依托单位：
Forschungseinheit Marine Geodynamik
依托单位国家：
德国
项目类别：
Infrastructure Priority Programmes
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/319238429?language=en
关键词：
Structure petrophysics oceanic Crust Lithosphere

项目摘要

Seismic anisotropy of the Earth´s oceanic crust and lithosphere is globally observed, and usually explained by crystallographic preferred orientations (CPO) in peridotites and/or deformed gabbros. While this model may be adequate for fast-spreading at mid oceanic ridges, deformation in slow-spreading environments brings about hydration and fundamental changes in mineralogy that alters elastic properties. Here it is proposed to conduct a neutron and synchrotron diffraction study of CPO in a suite of samples from the mafic-ultramafic rocks of Atlantis Massif, to gain fundamental insight in petrophysical properties of oceanic basement in a slow-spreading environment. Atlantis Massif was drilled and cored during IODP Expedition 357, and the rocks recovered are considered an ideal test case because of its excellent exposure and structural control through the network of drillsites. Elastic constants of the protolith minerals and those of the alteration products predict an increase of elastic and, thus, seismic anisotropy with deformation and hydration. This prediction is in contrast to observations made by seismological studies pointing to lower anisotropies of slow-spreading crust than those observed in normal or fast spreading environments. To analyze and explain this important disconnect between tectonic models and seismological observations is the main motive of the planned study.

在全球观察到地球的海洋壳和岩石圈的地震各向异性，通常由橄榄岩和/或变形的gabbros中的晶体学首选方向（CPO）解释。尽管该模型可能足以在海洋脊中快速扩张，但慢速环境中的变形带来了矿物学的水合和基本变化，从而改变了弹性特性。在这里，提议在Atlantis massif的一组样品中对CPO进行中子和同步衍射研究，以在慢速环境中获得海洋基质的石油物理特性的基本见解。在IODP Expedition 357期间钻了和核心亚特兰蒂斯地块，而回收的岩石被认为是理想的测试用例，因为它通过钻探网络具有出色的曝光和结构控制。原石矿物质的弹性常数和改变产物的弹性常数可以预测弹性的增加，从而增加了地震各向异性，并具有变形和水合。该预测与在正常或快速扩散环境中观察到的慢性外壳各向异性较低的地震研究的观察结果相反。分析和解释构造模型和地震学观察之间的这一重要脱节是计划研究的主要动机。