Upper Cretaceous Ostracoda Fossil Of Yadong, Southen Tibet

Cretaceous, a very important era in Earth history, witnessed many geological events in paleontology, paleoocean and paleoclimate. The study of these events can help us to understand the change in paleogeography, paleoenvironment and paleoocean during Cretaceous.Cretaceous marine strata, which yield abundant microfossils such as foraminfera, radiolarian and ostricod, is well outcropped in southern Tibet.The study area is located in the Tuna, Yadong, southern Tibet, which belongs to Southern Tethyan Himalaya subzone. This paper focuses on the ostricod biostraigraphy of the Late Cretaceous of the Jinsangsibei section, Tuna. Based on the study of the ostracads from the Jinsangsibei section, some conculsions could be drewn as followings.1. Abundant ostracod yield from this section, which include 38 species of 18 genus, and three planktic foraminifera biozones are recognized (in ascending order): Argilloecia acuminata—Parakrithe dimorpha zone; Monsmirabilia ovata—Cytherella retiangula zone; Bairdia sp.7—Brachycythere subdotata zone.2.According to the age of Dicarinella asymetrica zone which yield in the same layer, it can be concluded that the age of Argilloecia acuminate-Par-akrithe dimorpha zone should be late Santonian. And the age of the co-occurred Globotruncanita elevate zone also can give an early Campanian age to Bairdia sp.7.3.Based on the study of the ostricod assemblages, the age of the strata of the Jinsangsibei section could be inferred as late Santonian—early Campanian. It is suggested that, the sea level should fall in the study area during late Cretaceous.