【摘要】 橄榄岩的蛇纹石化是大洋中不可忽略的重要地质过程,近年来引起广泛关注。大洋橄榄岩的蛇纹石化主要发生在洋中脊和汇聚板块边缘等环境中,大洋蛇纹岩典型的矿物组合包括:蛇纹石±磁铁矿±滑石±水镁石±角闪石。其中蛇纹石根据其矿物的晶体结构特征可分为利蛇纹石、纤蛇纹石和叶蛇纹石3种类型;偏光显微镜下可将蛇纹石结构划分为3类:假晶结构、非假晶结构和过渡结构。橄榄岩的蛇纹石化不仅会改变岩石的物理性质,如导致岩石密度的减小和地震波速的降低、影响橄榄岩的磁性等,而且也会对橄榄岩的流变性产生重要影响。大洋超基性岩系热液系统的发现,进一步激发了研究者们对大洋橄榄岩蛇纹石化研究的兴趣。与橄榄岩蛇纹石化相关的喷口流体含有较高的H2和CH4含量,此外,蛇纹石化是一个放热反应,可以驱动热液循环,导致Lost City等中低温型热液系统的出现。更多还原

【Abstract】 Serpentinization of peridotites is a non-negligibly important geologic process in the oceans,which has attracted widespread attention in recent years.Serpentinization of the oceanic peridotites occurred largely in tectonic settings of mid-ocean ridges and convergent margins.A typical abyssal serpentinite is made up of serpentine minerals ± magnetite ± talc ± brucite ±amphibole.The three dominant species of serpentine minerals are lizardite,chrysotile and antigorite.Serpentine textures under the polarizing microscope can be divided into three categories: pseudomorphic textures,non-pseudomorphic textures and transitional textures.The physical properties of abyssal peridotites are strongly modified by serpentinization: serpentinization is responsible for a strong decrease in density and seismic velocities,furthermore,the magnetic properties of peridotites are also strongly affected by serpentinization;in addition,serpentinization of peridotites also changes the rheology of the altered rocks.The discovery of ultramafic hosted hydrothermal systems further arouses the interest of researchers in serpentinization of oceanic peridotites.Vent fluids associated with serpentinization of peridotites contain high concentrations of H2 and CH4.Serpentinization is an exothermic reaction and can drive hydrothermal circulation,resulting in the occurrence of low-medium temperature hydrothermal system like Lost City.更多还原