The Characteristics of the Biostratigraphic Chemical Elemental Combinations and Taphonomic Environmental Analyses of the Latest Miocene Deposits in Zhaotong, Yunnan
Zhang Yuguang et al.
We collected 16 samples from the 11 fossiliferous layers respectively within Zhaotong Formation in Shuitangba, representing the late Miocene lacustrine deposits of Shaoyang District, Zhaotong Yunnan. 19 biogenic elements were analyzed from these samples using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometry). Based on the biogeochemical theory, the results indicate the potential reason of the abundant vertebrate fossil assemblages preserved in the basin during latest Miocene. Chromium and strontium were ingested through food and water by the animals inhabited around; the two elements reached in a high abnormal level in organism by long term accumulation, caused the physiological function disorder of these animals and finally led to the regional faunal extinction. In addition, according to the characteristics of the chemical composition and the sedimentary features of the fossiliferous beds, the paleoenvironment of the region was considered as lakes, swamps or off-shore lake with low hydrodynamic condition; climate also experienced the gradual shift from humid and warm to dry condition during latest Miocene.
Keywords: Latest Miocene, Biostratigraphy, ICP-AES, Palaeoenvironment, Zhaotong of Yunnan