Analyze Rock Character And Tectonic Feature About Heishishan Melange In Tibet Qiangtang Basin

The gangtangcuo region is western part of Paleo-Tethys suture in Tibet qiangtang basin. Heishishan melange is taken shape in subduction .siltstone, sily slate are matrix, and basalt, chert, gabbro,diabase, metamorphic rocks are part of Heishishan Melange as block.Matrix and block is tectonic contact.siltstone, sily slate are abyssal sendimentery rock in active continental margin , passive continental margin and island arc. Metamorphicfine sandstone is sendimentery rock forming in moist&semi-arid littoral condition in active-continental margine as block. Most of basalts are island arc tholeiite ,which are in active continental margin, oceanic island tholeiit, oceanic island basalt, T-mid ocean ridge basalt as block. They are residues at collision between oceanic crust &continental crust. Basalts have different origin from metasomatic mantal &transitional mantal.Basalt,gabbro,diabase, pyroxenite, siltstone,which are in heishishan mélange, occur different metamorphism, concluding zeolite facies, prehnite-pempellyite facies, low-green schist facies, MV- green schist facies.So heishishan melange is a rock mix that exists different material origin& sendimentery environment&evolutional sequence from magma& metamorphism.