滇西藏东三江地区主要地块碰撞拼合的古地磁分析

The palaeomagnetic study of the collision and collage of major land-masses in the Nujiang-Lancangjiang-Jinshajiang area in western Yunnan and eastern Xizang

关键词:  三江地区  古地磁  滇西藏东

Key words:  Nujiang-Lancangjiang-Jinshajiang area  Palaeomagnetism  western Yunnan and eastern Xizang

摘要:

利用古地磁数据,结合与构造活动有关的沉积记录以及古生物地理信息,对华南、思茅、保山、缅泰、印支、拉萨和喜马拉雅地块进行了古纬度和纬度运移量的对比研究,以确定云南西部三江地区主要地块的碰撞拼合历史。结果表明:(1)思茅地块可能源于华南地块;(2)保山和缅泰地块在晚石炭世至晚二叠世发生快速北移;(3)保山与华南地块于晚二叠世碰撞之后,和缅泰地块、华南地块以及印支地块继续向北漂移,直到晚三叠世;(4)保山与华南地块间的古特提斯洋可能于早志留世张开,晚二叠世闭合。

Abstract:

In order to explore the evolution and history of the collision and collage of the major landmasses in the Nujiang-Lancangjiang-Jinshajiang area in western Yunnan and eastern Xizang, the comparative study has been made for the migration of the present-day latitudes and palaeolatitudes of South China, Simao, Baoshan, Burma-Thailand, Indo-China, Lhasa and Himalaya landmasses in the light of the palaeomagnetic data in integration with the existing sedimentary records and palaeogeographic information. The results show that:(1) the Simao landmass may be derived from the South China landmass; (2) the Baoshan and Burma-Thailand landmasses once drifted rapidly northwards during the Late Carboniferous and Late Permian; (3) after the collision with the South China landmass during the Late Permian, the Baoshan landmass continued to drift northwards together with the Burma-Thailand, South China and Indo-China landmasses till the Late Triassic, and (4) the Palaeo-Tethyan Ocean between the Baoshan and South China landmasses might be opened during the Early Silurian and closed during the Late Permian.