High- and low-temperature alteration of ultramafic oceanic crust: Mineralogy, geochemistry and isotope characteristics of hydrothermal systems at the Mid Atlantic Ridge between 14° and 15°N

超镁铁质洋壳的高温和低温蚀变：北纬14°至15°大西洋中脊热液系统的矿物学、地球化学和同位素特征

• 批准号: 5415977
• 负责人: Dr. Klas S. Lackschewitz
• 金额: --
• 依托单位: GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 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/5415977?language=en
• 关键词: low; temperature; alteration; ultramafic; oceanic

Hydrothermal deposits may be created as a result of either ultramafic rock-seawater or basalt-seawater reactions. Previous studies of slow-spreading ridges indicate that in addition to basalts ultramafic rocks often make up a significant proportion of the upper oceanic crust. These ultramafic rocks are partially to completely serpentinized, indicating that reaction of hydrohtermal fluids with upper mantle lithologies is a common process. The present projekt aims to sample the serpentinized ultramafic-hosted hydrothermal systems in the Logatchev field region directly south of the Fifteen-twenty Fracture Zone at the Mid-Atlantic Ridge. The occurrence of both high- and low-temperature ultramafic-hosted systems leads to pronounced differences in the secondary mineralogy when compard to basalt-hosted hydrothermal systems. Our main aims are to study the mineralogical, geochemical and isotopic composition of bulk and clay samples to quantify the chemical changes related to serpentinization. From this we hope to better define the significance of reactions between seawater and lower crust/upper mantle in global lithosphere-seawater-exchange. To achieve these aims we will have a ship-based sampling of the Mid Atlantic Ridge between 14°45'N and 15°05'N using the RV Meteor from 15.1. to 13.2.2004 (M60/3).

热液矿床可能是超镁铁质岩石-海水或玄武岩-海水反应的结果。以前对缓慢扩张的海脊的研究表明，除了玄武岩之外，超镁铁质岩石通常在大洋上部地壳中占很大比例。这些超镁铁质岩石部分或完全蛇纹岩，表明热液与上地幔岩性的反应是一种常见的过程。本项目旨在对中大西洋海脊15-20断裂带正南面Logatchev油田地区的蛇纹岩化超镁铁质热液系统进行采样。与玄武岩赋存的热液系统相比，高温和低温超镁铁质赋存系统的赋存导致次生矿物学上的显著差异。我们的主要目标是研究散体和粘土样品的矿物学、地球化学和同位素组成，以量化与蛇纹岩作用有关的化学变化。由此，我们希望更好地确定海水与下地壳/上地幔之间的反应在全球岩石圈-海水交换中的意义。为了实现这些目标，我们将使用RV Meteor从15.1开始对14°45‘N到15°05’N之间的大西洋中脊进行基于船舶的采样。至2004年2月13日(M60/3)。