Study Of The Permian-Triassic Boundary Strata Of Jin Xi Profile In Zhijin Region Of Guizhou

This paper takes the paleobiology and sedimentary microfacies in Guizhou Zhijin area as the object of study,via data collection, geological survey,experimental measurement and theoretical analysis, the biological development characteristic, carbonate microfacies,etc, are researched on the system.The results show that:The end-Permian mass extinction and early-Triassic biological recovery were the greatest change in phanerozoic history of life.They not only witnessed tremendous changes of marine ecosystem structure,but also promoted the transformation from the Paleozoic biota to modern biota.The type of end-Permian mass extinction is one of the hot issues of present paleontological research.Moreover, one can discern the global or local environment of paleontological characteristic and history of sedimentary facies via the research on detailed paleontological characteristic and sedimentary microfacies.We try to recover the former biological combination and the depositional model combination at the slope facies carbonate sedimentary zone located in the middle of upper yangtze via research and analysis on paleontology of Guizhou Zhijin area.The biological and sedimentary events occurred in the turn of the Permian and Triassic can be evidenceded from the perspective of paleontology and sedimentary petrology.The particles and bioclastic components of the section were observed by microscope,and ten kinds of bioclastic and five kinds of rock types,i.e., micrite, crumb grain marl, raw crumbs packstone, crumbs limestone particles and crystalline limestone,were recognized.Furthermore, Guanghai slope sedimentary environment with 2 types of sedimentary subfacies,i.e.,middle slop and out slop,were recognized.The boundary strata was Sliced pieces and researched with an identify of 11 genera and 16 species small foraminifera fossil.This discovery provide a new evidence for the research on the mass extinction pattern at the end of the Permian.The boundary of Permian and Triassic at Guizhou Zhijin area is determined at bottom of layer A5(layer six) and top of A4(layer 5-3) via comparison and analysis on Meishan section.