Chronostratigraphic classification of zoige basin since late pleistocene and its tectonic-climate significance

Since stratigraphic formation is influenced by tectonic activities and climate since late Pleistocene, it is important to build the stratigraphic sequence to improve the research of active tectonics, climatic change and landform factors. Zoige Basin is located in the eastern edge of Tibet Plateau where the tectonic is active and the Chinese monsoon is strong. The research of stratigraphic sequence is closely related to the tectonic activities and climate changes. Based on 26 typical stratum profiles revealed by lacustrine boreholes, terraces, peat deposits and trenching, 203 isotope dating data were obtained by AMS and OSL methods. We conduct a stratigraphic correlation and classification in Zoige Basin since the Late Pleistocene. Sedimentary cycles are divided into six sedimentary rhythms(75~42ka, 42~37ka, 37~20ka, 16~11ka, 11~4ka and 4~0ka)and six marker beds(fine sand of 75~55ka and 22~20ka, gray silt deposit or gravel deposit of 13~9ka, black sandy clay containing carbonaceous deposits of 4ka, 2ka and 0.3ka). There is a close relation between strata and tectonic-climate. On the one hand, sedimentary cycles coincide with climate change and have a good correspondence with ocean oxygen isotope. On the other hand, sedimentation characteristics is influenced by the persistent activities in neotectonic period of the east Kunlun fault zone on the north side and the Longrize fault zone on the west side. Marker beds and sedimentary cycles are compared with the strata in adjacent areas. It shows that climate change is the main factor affecting sedimentary cycle. The difference of stratum thickness and its spatial distribution is also affected by tectonic activity. © 2016, Editorial Office of Seismology and Geology. All right reserved.