Geological features of the metamorphic granitoids in the north area of Weihe river in Tianshui,Gansu

The north area of Weihe River is located in the joint of the Qilian-North Qinling orogenic belt.Based on studying in detail of the petrology,contact relation,deformation,metamorphism and so on,the metamorphic granitoids can be recognized and brokenup from metamorphic terrane.The main diagenetic stage and relevant rock types are the Middle Proterozoic assemblage of gneissoid granodiorite-adamellite and the Sinian schistosity diorates.The important information about the tectonic environments was obtained obtained from the discrimination diagram.The Middle Proterozoic granitoids was an intraplate type producted in transitinal crystalline basement before plate collision.The Sinian granitoids are immediately related the plate collision,they were formed int he plate collision mounain-building period-post collision elevation period.The import ant evidence of plates collision of the granitoids are recorded between Qilian and North Qinlingin.