西南三江造山带地层区划

摘要

西南三江为一复杂造山带,由特提斯大洋板块的怒江-孟连主大洋及欧亚大陆板块的扬子陆块大陆边缘弧盆系、冈瓦纳大陆板块北缘弧盆系构成.随着特提斯大洋怒江-孟连洋俯冲、消亡,后板块发生碰撞、走滑及岩浆岩侵位等,形成了现今由板块缝合带、增生杂岩带构成的西南三江造山带,造就了复杂的地层系统,包含史密斯地层、有限史密斯地层,非史密斯地层.本文突破"传统地层学"概念,按"构造地层学"的现代地层学概念建立了西南三江地层格架,划分出欧亚大陆板块的北羌塘-三江地层大区、特提斯大洋板块的班公湖-怒江-孟连构造-地层大区、冈瓦纳大陆板块的冈底斯-腾冲地层区.%The Nujiang-Lancangjiang-Jinshajiang area as a complicated orogenic zone in southwestern China consists of the Nujiang-Menglian ocean basin systems within the Tethyan ocean plate,the Yangtze continental marginal arc-basin systems within the Eurasic plate,and the northern Gondwana plate arc-basin systems. The subduction and consumption of the Nujiang-Menglian ocean basin,post-plate collision,strike-slipping and emplacement of magmatic rocks led to the formation of the present-day Nujiang-Lancangjiang-Jinshajiang orogenic zone composed tectonically of plate suture zones and accretionary complex terranes,and stratigraphically of the Smith strata,limited Smith strata and non-Smith strata. Unlike the concept "traditional stratigraphy",the new stratigraphic framework of the Nujiang-Lancangjiang-Jinshajiang area in southwestern China is constructed in the present paper according to the "tectostratigraphy",a modern stratigraphic concept. As a result,three stratigraphic provinces have been separated,including the North Qiangtang-Nujiang-Lancangjiang-Jinshajiang stratigraphic realm within the Eurasian plate,Bangong Lake-Nujiang-Menglian stratigraphic realm within the Tethyan ocean plate,and Gangdise-Tengchong stratigraphic realm within the Gondwana plate.