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

与15°20'转换断层相邻的超缓慢扩张的大西洋中脊段的特征是区域尺度的地幔橄榄岩暴露在海底。这些地幔岩是在伸展应变作用下沿沿着低角度正断层的构造运动中被折返出来的。放热蛇纹石化过程中的橄榄岩是普遍的，并有助于积极洛加切夫热液领域的能量收支。在ODP第209航次期间，将在靠近山脊轴的橄榄岩中钻几个孔，最深可达200 m。这将提供一个独特的机会，研究地幔岩石的蚀变过程中的原位材料在一个定义的地球动力学背景。该研究项目的主要目标是利用矿物学（XRD、SEM、TEM）地球化学（XRF、ICP-MS、Microprobe）和同位素（dD、d180、87 Sr/86 Sr）分析全面重建流体/岩石相互作用期间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平衡和“深部生物圈”的生存条件也很重要。

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".