西藏的蛇绿岩

本文对西藏地区的雅鲁藏布江、班公湖—怒江二条蛇绿岩（带）剖面层型的形成时代、构造环境、侵位机制,以及它们在岩石学和地球化学的基本特征和演化历史,进行了系统的分析与对比。

OPHIOLITES OF TIBET

There are two ophiolite belts in Tibet: the Yarlung Zangbo River ophiolite belt in the south （called the south belt for short） and the Bangong Lake- Nujiang River ophiolite belt in the north （called the north belt for short）. They respectively represent two plate junctures that originated in different times in the Mesozoic. Ophiolites in the north belt formed in the Late Triassic- Jurassic,The ophiolite section has been mostly destructed by strong structural movements and the sequence has been disintegrated and has actually become ophiolitic melanges. Ophiolites in the south belt formed later than those in the north belt,in the Early Cretaceous （139 Ma） and were emplaced tectonically at the end of the Late Cretaceous （81 Ma）. But a relatively complete ophiolite section may be still observed in the Xigaze area. There are many significant differences between the two belts in respect to the petrology,geochemistry and regional geological settings,which reflect their different conditions of formation and his tories of evolution.