Hydrothermal fluid-rock interaction in the upper mantle at the mid-atlantic ridge, ODP Leg 209

与15°20′转换断层相邻的大西洋中脊段以海底地幔橄榄岩的区域尺度暴露为特征。这些地幔岩是在伸展应变作用下沿低角度正断层的构造运动中被挖掘出来的。橄榄岩中普遍存在放热蛇纹岩化过程，对活跃的Logatchev热液场的能量收支有贡献。在ODP第209阶段，将在与脊轴平行的橄榄岩中钻几个深达200米的孔。这将提供一个独特的机会，在确定的地球动力学背景下，研究地幔岩石在原位物质上的蚀变过程。本课题的主要目的是利用矿物学（XRD、SEM、TEM）、地球化学（XRF、ICP-MS、Microprobe）和同位素（dD、d180、87Sr/86Sr）分析，全面重建流体/岩石相互作用过程中的矿物反应和蚀变条件。了解这些蚀变过程不仅与热液块状硫化物矿床的成因有关，而且对全球元素转移收支和“深层生物圈”的生存条件也具有重要意义。

The ultra-slow spreading mid-Atlantic ridge segments adjacent to the 15°20' transform fault are characterized by regional scale exposures of mantle peridotites on the seafloor. These mantle rocks have been exhumed by tectonic movements along low-angle normal faults due to extensional strain. Exothermic serpentinization processes within the peridotites are prevalent and contribute to the energy budget of the active Logatchev hydrothermal field. During ODP Leg 209 several, up to 200 m deep, holes will be drilled into the peridotites paralell to the ridge axis. This will provide an unique opportunity to examine alteration processes of mantle rocks on in-situ material in a defined geodynamic context. The primary objective of this research project is a comprehensive reconstruction of the mineral reactions and alteration conditions during fluid/rock interaction using mineralogical (XRD, SEM, TEM) geochemical (XRF, ICP-MS, Microprobe) and isotopic (dD, d180, 87Sr/86Sr) analyses. Understanding these alteration processes is not only of relevance to the genesis of hydrothermal massive sulfide deposits but is also important with regard to the global element transfer budget and the living conditions of the "deep biosphere".