滇西苍山变质岩研究新进展

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

运用构造解析和构造—岩层填图新方法，将苍山变质岩划分为黄龙潭、石门关、龙泉峰、中和寺、茫涌溪和罗坪山６个岩组。据其变形、变质特征和同位素年龄，将黄龙潭、石门关岩组归并为古元古代沟头箐岩群（锆石Ｕ－Ｐｂ年龄２０００Ｍａ），龙泉峰、中和寺、茫涌溪岩组归并为中元古代苍山岩群（Ｓｍ－Ｎｄ模式年龄１０００—１４００Ｍａ），罗坪山岩组则确定为晚元古代（Ｒｂ－Ｓｒ等时线年龄６９８Ｍａ）。

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).