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

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.