BLUESCHIST BELT IN CHINA AND ITS TECTONIC SIGNIFICANCE

On the basis of previous studies,the blueschist belt in China can be divided into 20 parts according to the metamorphic age and original place. This paper selects some typical blueschist belts of different times to discuss their characteristics( such as distribution area,gross scale,the features and formation age of the original rock and mineral combination), and analyze their geological genesis. The generation patterns of China's blueschist belts are complicated,they are all associated with the subduction,and mostly belong to the B-type subduction. Part of regions,however,also are superposed by the A-type subduction which are UHP and HP metamorphic belts( such as Arkin,Dabie belt,Namjagbrawa Subei Myitkyina band,etc.). China's blueschist belts can be divided into four formation ages,which are the Proterozoic( Jinning period),the Paleozoic( Caledonian, Hercynian), the Mesozoic( Indosinian to Yanshanian) and the Cenozoic( Himalayan). And the formation of the blueschist belts in each period are mostly related with the subduction of the ocean basin in the process of China's terrane accretion,and some also are effected by the superposition of the later intracontinental subduction( high-ultrahigh pressure subduction) at some specific areas.