Biostratigraphic Of The Seep Carbonates In Gamba,Southern Tibet

Cold Seep is distributed in continental margin, and deposits in the seafloor under the interface. It is a kind of fluid activity caused by the flowing of the fluid which is mainly composed of water, hydrocarbons(gas and oil), hydrogen sulfide and finegrained sediments and with a similar temperature as seawater, into the overlying water The environment of cold seep has been widely appreciated because it often produces gas hydrate which has great resource potentiality and may lead to environmental disaster and also develops a specific biota that dependents on the chemical energy and nutrient of the fluid.Cold seeps now known are widely developed in the seafloor of the continental margin. The carbonate rocks or fossils as the marks of the ancient Cold Seep has been reported from the Devonian to Quaternary strata in the world but few in the mainland of China. The First ancient seep carbonate in the mainland of China was reported from the late Cretaceous in Xigaze, Tibet. We went to Qiangdong, nearby the section of the paper, in Gamba, Xigaze, Tibet. In this thesis, the Late Cretaceous seep carbonates in Gamba, Tibet has been studied in such aspects as isotope geochemistry and biostratigraphy, the focus of which is the age determination of the seep carbonate strata.21 species of 9 foraminiferal genus identified in this thesis were divided into two foraminifera biozones as Dicarinella primitive zone and Dicarinella concavata zone, Which provides a Late Cretaceous Coniacian age for the seep carbonates strata in the study.The most important identification of the seep carbonates is the carbon and oxygen isotope values were negatively biased. We analyzed the external features and the carbon and oxygen isotope of the samples. The results of δ13C and δ18O test show that both of δ13C and δ18O values of the samples are negative and close to those by previous reports. A preliminary conclusion has been made that these samples from the study area should be seep carbonates.