Tectonic-Lithofacies Palaeogeography Of The Carboniferous In Qinghai-Tibetan Plateau

The Qinghai-Tibet Plateau, a super orogen system, is confined by three stable paleo- plates(the North China-Tarim Plate, the Yangtze Plate and the India Plate) and bounded by Kangxiwar- Muztag-Maqin-Mian Xian-Lueyang junction zone and Bangong Lake- Dingqing-Bitu-Changning-Menglian junction zone. From the north to the south the super plateau is divided into three tectonic regions:the Qingling-Qilian-kunlun tectonic region of the Early Paleozoic Pan-Cathaysian continent, the Qiangtang -Sanjiang tectonic region of the Pan-Cathaysian continent in Late Paleozoic and the Gangdise-Himalaya tectonic region of the Late Paleozoic-Mesozoic north margin of Gondwana.The geological evolution process of the Tibetan Plateau has a characteristic of multi-stages including Ocean-Continent Transition and Basin-Mountain Transition. Effectively the study of the structure of the Plateau during Carboniferous could provide sharply-evidences of the tectonic evolution of paleo -Tethyan and the relationship of collision and subduction to rebuild the Ocean-Continent distribution and the spatial alloction of the basins. Moreover the evolution of the Tectonic Paleogeography represents multi-characteristics of the time-spatial structure of the archipelagic arc basin systems and the sedimentary facies are the boundary surfaces of lithofacies paleogeography. Totally the study aims to reconstruct the tectonic-paleogeography of the Tibetan Plateau during Carboniferous and present the characteristics of the lithofacies paleogeography.Achievements and advances of the study include the followings:Part one:Confirmated the division system of Carboniferous geotectonic facies of Tibetan Plateau, and made integration and combination of the geotectonic facies of tectonic and lithofacies paleogeography of the plateau at that Age; also reduced 13 super facies and 26 facies to 5 groups and 3 systems in order to meet the demand of the related research as well as graphed the map of Carboniferous tectonic-lithofacies paleogeography of the Tibetan Plateau.Part two:Summarized and modified the Carboniferous regional tectonic framework of the Tibetan Plateau as a new pattern of one Ocean and two Continental Margin Systems, the north and the south. One Ocean is the Bangong Lake-Shuang Lake- Nujiang River- Changning-Menglian Suture Zone, the paleo- Tethyan ocean. In Carboniferous the ocean drove into the subduction stage. The two Continental Margin Systems were the north part of the Pan-Cathaysian continental margin and the south part of Gondwana continental margin. Meanwhile the Caledonian Movement had ended at the north of Qilian Mountain region and the archipelagic arc basin systems developed at the south of Qilian Mountain region. The Gondwana continent start its transformation of its geological background from the passive continental-margin-Epicontinental sea into the active continental-margin and the incipient movements of island arc orogenesis staged to agitate the Gangdise Mountains.