Geochemical Characteristics Of Trace Element Of Permian-Triassic Boundary Strata In Western Margin Of Yangtze Block

In recent decades, the People are concerned particularly about some incidents on the geological history ,in particular on the collective mass extinction. There are five of the serious mass extinction in geological history,Permian-Triassic mass extinction is the largest and most serious catastrophic event in the geological history. Over the past decades, many geologists have studied the global Permian-Triassic boundary formation from different angles, different aspects and put forward a series of hypothesis about the causes of the mass extinction. However, these divergent hypothesis is still no consensus conclusion.In this thesis, the object of study is that the Permian-Triassic boundary strata of different regions in the western margin of the Yangtze, Mesozoic and Paleozoic strata develop well in this area that is a good condition about study of Permian-Triassic. Through observations and measurements, and collect and record claypan from boundary strata section, We analyze the composition of trace element geochemistry. According to the ancient sedimentary and geochemistry of the ancient oxygen, we analyze the facies and the ancient environment of deposition at the turn of the Permian-Triassic in different areas. We study primarily the source of clay on the boundary, And speculate the reasons of Permian-Triassic mass extinction .Via use tracing of trace elements and study of REE standardized charts and other trace elements. The conclusions are as following:(1) At the turn of the Permian-Triassic is a regression stage in Guangyuan and Jiangyou area.when The region's marine deposition environment is oxidation, not happen oceanic anoxic events. Therefore, the oceanic anoxic events was not caused this region mass extinction at the turn of Permian-Triassic.(2) Through geochemical study of the trace element show that Permian-Triassic boundary strata has usually the trace element geochemical anomalies prevailing western margin of in Yangtze block.therefor,author thinks that the mass extinction may have close relations with Those at the turn of the Permian-Triassic.(3) The clay from Jiangyou and Guangyuan areas of sea facies in the Permian-Triassic boundary section have not only may relate to neutral-acidic volcanic rock but also relate to the original Mantle material, or extraterrestrial material that (similar to the material composition of the earth).(4) The clay from Emei area of continental facies in the Permian-Triassic boundary section have Trace element geochemistry of well-preserved because of marsh sedimentary environment.these Material source may be related to the original material of the mantle and extraterrestrial material(similar to the material composition of the earth). The source of these substances may not only impact the Emei Mountain region, but also other regions may have those substances.(5)The clay from the lotus pool of Panzhihua area in the Permian-Triassic boundary section exist geochemical anomalies, it perhaps results from mixing of cidic volcanic rock and the original mantle material similar to the material composition of the earth).