The multiple island arc-basin systems and their evolution in the Gangdise tectonic belt, Xizang

The Gangdise tectonic belt intermediate between the Bangong-Nujiang and Yarlung Zangbo suture zones is not a simple continental mass; it has displayed a long and complex evolution of multiple island arc-basin systems since the Late Palaeozoic, i. e. ocean-continent transition during the Devonian to Middle Triassic, basin-range transition during the Late Triassic to Cretaceous and crust-mantle transition during the Paleogene to Quaternary. The tectonic zone may be divided into ten secondary tectonic units from north to south:⑴ Nyainrong Late Palaeozoic-Mesozoic residual magmatic arc;⑵ Guiya-Yilashan-Xagquka arc-arc collision suture zone;⑶ Nagqu backarc basin;⑷ Baingoin-Lhari Jurassic-Cretaceous residual magmatic arc;⑸Yunzhug Zangbo-Nichang arc-arc collision suture zone;⑹ Xainza Palaeozoic carbonate platform;⑺ Gyaringco-Namco-Gyuzela Jurassic arc-arc collision suture zone;⑻Coqen-Nyainqentanglha Early Permian-Mesozoic is land-chain zone;⑼Milashan-Songduo arc-arc collision suture zone;⑽South Gangdise Mesozoic-Cenozoic volcanic-magmatic arc.The Bangong-Nujiang suture zone is interpreted as a major suture zone created by the subduction and collision of the Tethys Sea, and the Yarlung Zangbo oceanic basin represents the small backarc oceanic basin in the southern part of the Tethys Sea.