GANGMACUO-SHUANGHU BLUESCHIST BELT IN CENTRAL QIANGTANG RAEA OF TOBET AND ITS GEOLOGICAL SIGNIFICANCE
HuKe; LiCai;Chen Liren(Changchun Universily of Earth Sciences.Changchun 130026)Hong Yurong(Regional Geological Surveying Party,Tibet. Lasa 851400)
The Qiangtang area is divided into two parts by the Gangmacuo-Shuanghu blueschist belt.The southern part is composed of Gangwana glacialsedimentary and tholeiite while the northern, of Yangtze continental sedimentary. Crossite+epidote and crossite+chlorite in blueschist give the metamorphic conditions of320～400℃,0.6～0. 7 GPa,The geology of the bcueschist,together with the dating ofcrossite(￣40Ar-￣39Ar,method),proves that the HP metamorphism took place from earlyPermian to early triassic and developed on the regional greenschist facies. The authorsbelieve that the blueschist belt marks the boundary between Gangwana and Lauriacontinents during the late paleozoic in Tibet.