Cryogenian and Ediacaran integrative stratigraphy, biotas, and palaeogeographical evolution of the Qinghai-Tibetan Plateau and its surrounding areas

The complex evolutionary history of the Qinghai-Tibetan Plateau and its surrounding areas, including the continental blocks (Indian, Lhasa, South Qiangtang, Tarim, Olongbuluk, Central Qilian, Alxa, North China, Yangtze, Central Iran and Oman) and the orogenic belts between them, has long been the frontier in Earth science research. The Cryogenian and Ediacaran strata are extensively distributed in these blocks. Specifically, relatively complete Cryogenian and Ediacaran successions have been discovered in Oman, Indian, Yangtze, and Tarim blocks, while only the Ediacaran successions have been reported in Iran, the South Qiangtang, Central Qilian, Alxa, and North China blocks. Based on previous studies together with the integration of new materials and advancement obtained through the Second Tibetan Plateau Scientific Expedition and Research, this review aims to synthesize a correlative stratigraphic framework of the representative Cryogenian and Ediacaran sequences from the Qinghai-Tibetan Plateau and its surrounding areas. Furthermore, the Cryogenian and Ediacaran biotas and major geological events in these areas are comprehensively discussed in aspects of current research status. The results indicate that, in general, Ediacaran fossils of each area exhibit distinct features in preservation and assemblage composition, but the typical late Ediacaran fossils Cloudina and Shaanxilithes have been reported from most of these areas. In addition to the two global Cryogenian glaciations, late Ediacaran glaciogenic deposits are extensively recorded in the areas within and around the northern Qinghai-Tibetan Plateau (including the North China, Alxa, Central Qilian, Olongbuluk, and Tarim blocks, and the North Qilian Accretionary Belt), as well as central and southern Iran. However, further research is required to determine the age, distribution, and origin of these late Ediacaran glaciogenic deposits. Meanwhile, the middle Ediacaran DOUNCE/Shuram Excursion is widely documented in the Qinghai-Tibetan Plateau and its surrounding areas. The available data show that, after the break-up of the Rodinia supercontinent, most of the continental blocks in the areas were located along the northern margin of East Gondwana and a few (such as North China) were located between the Gondwana and Laurentia. In general, the paleogeographic evolution of most of these blocks during the Cryogenian and Ediacaran remains disputatious, necessitating further research to resolve the controversies surrounding their paleogeographic reconstruction models during this critical time interval.