班公湖—双湖—怒江—昌宁—孟连对接带时空结构——特提斯大洋地质及演化问题

Space-time structure of the Bangonghu-Shuanghu-Nujiang-Changning-Menglian Mega-suture zone: A discussion on geology and evolution of the Tethys Ocean

关键词:  特提斯大洋  班公湖—双湖—怒江—昌宁—孟连对接带  洋板块地质

Key words:  the Tethys Ocean  the Bangonghu-Shuanghu-Nujiang-Changning-Menglian mega-suture zone  geology of oceanic plate

摘要:

班公湖—双湖—怒江（中北段）—昌宁—孟连对接带广泛出露特提斯大洋岩石圈俯冲消减过程中产生的不同时代、不同构造环境、不同变质程度、不同变形样式的洋板块构造地层系统、增生混杂的构造—岩石组合体，可识别出增生的远洋沉积岩、海沟浊积岩、古生代—中生代蛇绿岩、蛇绿混杂岩、洋岛-海山消减增生楔、洋底沉积增生杂岩，基底残块以及以蓝片岩、榴辉岩为代表的高压—超高压变质岩带，记录了青藏高原原古特提斯大洋形成演化的地质信息。班公湖—双湖—怒江—昌宁—孟连对接带是青藏高原中部一条重要的原古特提斯大洋自北向南后退式俯冲消亡的巨型增生杂岩带，构筑了冈瓦纳大陆与劳亚-泛华夏大陆分界带。

Abstract:

Tectonic-stratigraphic systems and their tectonic-rock assemblages,which are related to the subduction process of the Tethys Ocean and are of different geological epochs,tectonic settings,metamorphic degrees and deformation styles,are widely exposed within the Bangonghu-Shuanghu-Nujiang-Changning-Menglian mega-suture zone. In this paper,a number of specific rock types such as pelagic sedimentary rocks,turbidite rocks deposited in deep sea trenches,Paleozoic ophiolites and ophiolitic mélanges,Mesozoic ophiolites and ophiolitic mélanges,oceanic-island accretionary wedges,seamount accretionary wedges,debris of crystalline basements,high-pressure to super high-pressure metamorphic belts represented by glaucophane schist and eclogite rocks,have been identified. All of these tectonic-rock types and their assemblages recorded the geological information of the formation and evolution of the Paleo tethys Ocean on the Qinghai-Tibet Plateau.The Bangonghu-Shuanghu-Nujiang-Changning-Menglianmega-sututurezone is a giant complex accretionary zone.It played an important role in the receding subduction process of the Tethys from north to south,and it was the boundary zone between the Gondwana Continent and the Pan-Cathaysia Continent.