Paleoecology Of The Tibetan Tethys Cretaceous

Cretaceous was one important stage in the evolutional history of Earth, in which occurred a series of major global geologic events such as global warming event, oceanic anoxic event, oceanic oxic events, mass extinction events. Situated in the southern part of Asian, Qinghai-Tibet Plateau constitutes the main body of the famous global W-E giant structural realm: the Tethyan Himalayan tectonic system.Based on the study of the palaeoecologic data of Cretaceous microfossils, fossil carbonate microfacies, ichinofacies, biofacies and relative sedimentary structures of the southern Tibet, this paper explored the Cretaceous palaeoenvironment and evolutional process of the Tethyan Himalayas. The main rults obtarined from this study are as following:(1) 16 fossil carbonate microfacies (MF1~MF16), 13 biofacies (BF1~BF13), and 5 ichinofacies (Nereites,Zoophycos,Cruziana,Glossifungites and Skolithos ichinofacies)are recognized from the Cretaceous of southern Tibet.(2) During Cretaceous, a"Deep North and Shallow South"palaeogeographic pattern occurred in the Tethyan Himalaya: the southern Tethyan Himalaya subzone was located in a shelf envirnment; the northern Tethyan Himalaya subzone was located in a slope-ocean basin envirnment.(3) During Cretaceous, an obivous transgression-agression cycle occurred in Tethyan Himalayan regiond and sea: (1) Berriasia-Barrem: a transgression occurred in Tethyan Himalaya; (2) Aptian: the transgression scale enlarged and the sea-water sharply deepened, the Gamba-Tingri area evoluted into outer shel; (3) Early Albian: an agression occurred in Tethyan Himalaya; (4) Late Albian: a transgression occurred in Tethyan Himalaya and the sea-water again deepened; (5) Cenomanian-Earliest Turonian: during Cenomanian, a largest global transgression occurred in Tethyan Himalaya; (6) Turonian-Campanian: occurred in Tethyan Himalaya entered into an agression stage;(7) Maastrichtian: the ongoing subduction of the Indian plate into the Asian plate caused the uplift of the crust and then the large-scale aggression; (8) Latest Creataous-Earliest Paleocen: the earliest collision between the Indian and Asian plates caused the sharp uplift of crust and the shallowest envirnment.