【摘要】 <正> 蛇绿混杂岩是一种主要由构造作用形成的外观混乱的岩石体,是由普遍遭受构造剪切的、通常是蛇纹质岩石或沉积岩(通常是深海泥质岩)作为基质部分和混于其中的各种外来岩块和原地岩块所组成的。这种特殊组合的岩石体多出现于造山带。目前,大多数地质工作者把它作为板块消减带和古缝合线的标志之一。更多还原

【Abstract】 By comparison with the most ophiolitic melanges in the world, Litang ophiolitic melange has the following characteristics:(1) The matrix of ophiolitic melange in Litang is not serpentine or argillaceous rocks, but is volcanic rocks which consist of basaltic components and volcanic breccias originated by tectonic process;(2) Deformed matrix rocks do not possess plastic deformation type as common sight, but are characterized by dense cleavages.It is SF-tectonite encountered strong shear fragmentation;(3) This ophiolitic melange has distinct zoning.According to the character of blocks and deformed degree of the matrix, it may be divided into three belts: the Block composition in eastern belt is very complex, including such as limestone, sandstone, lava and so on, the basic rocks are deformed strongly and cleavage are developed;In medium belt, it characterized by autochthonous blocks, It consists mainly of pillow lava and gabbro, the deformation degree of basic volcaic rocks is lower than eastern belt. It is epuivalent to the broken formation Suggested by Hsu; The western belt consists mainly of abyssal sandstone and shale series intercalate chert and basalt beds. They were deformed weaker than the others. The origin is not sure, either a largeblock or a tectonic nappe. The deformation degree of basalt is stronger universally than allothigenous limestone blocks. The character of the former is a group of dense Cleavages, the latter shows rhombic shear broken. Observation in the field and laboratory suggested that basaltic rocks encountered complex deformation, the deformation and metamorphic prossess happened in the ocean flcor before they mixed with limestone,The ophiolitic melange in Litang located between Yangzi plate and Dege-Yidun plate. Ganzi-Litang sea basin were opened in late carboniferous and could be closed in late Triassic, whereas tectonic action lasted until Himalaya stage.更多还原