NEW ADVANCES IN THE STUDY OF THE CANGSHAN METAMORPHIC ROCKS IN WESTERN YUNNAN

By using the structural analysis and the new method of tectono rock stata mapping ,the Cangshan metamorphic rocks may be divided into the Huanglongtan,Shimenguan,Longquanfeng,Zhonghesi,Mangyongxi and Luopingshan Formations Complexes.According to the features of deformation and metamorphism and isotope ages ,the Huanglongtan and Shimenguan Formation Complexes may be merged into the Paleoproterozoic Goutouqing Group Complex（with a zircon U Pb age of 2000 Ma）,the Longquanfeng ,Zhonghesi and Mangyongxi Formation Complexes are merged into the Mesoproterozoic Cangshan Group Complex （with Sm Nd model ages of 1000 1400 Ma）,and the Luopingshan Formation Complex has been determined to be of Late Proterozoic age （with a Rb Sr isochron age of 698 Ma）.