The Study Of Distribution Of Late Paleozoic Siliceous Rocks In The Eastern Tethys Ocean

Through the research method of using point to represent integral and integrateing point with sphere, undertaking from the typical field profiles in late Paleozoic, and combining with different development characteristics in regional strata, this thesis comprehensively defines the distribution characteristics of different types of siliceous rocks in late palaeozoic in both North China and Yangtze region. Comprehensively analyzing the datum of lithofacies paleogeograpy and combining with different analysis methods of geology and geochemistry, this thesis has discussed the similarities and differences in sedimentary environment, genetic types and silicon source of different types of siliceous rocks, defined its distribution characteristics and accumulation regulation, and probed into the sedimentary response of siliceous rocks on the different evolution stages in North China and Yangtze region, and then extracted the ancient geography, climate and marine information in the siliceous rocks.Permian siliceous rocks in North China are mainly concentrated in the south of the North China, including chert nodules and strips in low Permian Taiyuan group, widely distributing in the southern margin of North China, and often used as an important symbol of stratigraphic correlation; several layers of radiolarian and sponge spicules siliceous rocks are mingled in mudstone in upper Permian Shangshihezi group, its distribution range is less than Taiyuan group. Previous studies show that siliceous rocks of Taiyuan group were formed in a continental margin environment, and affected by hydrothermal activities, the siliceous hot water might come from southern Mianlue ocean. The genesis of sponge spicules siliceous rocks in Shangshihezi group was associated with the flourish of the siliceous sponge, and it’s on behalf of the last widely and transient seawater intrusion of the whole of the late Permian in the southern of North China.Permian hot-water siliceous rocks in Yangzi region lasted longer and distributed wider than Norh China, most of the region showed strong hydrothermal sedimention, and also some were biogenic. Devonian siliceous rocks are widely distributed and has the characteristics of hot water sedimention, the jasper rocks, bedded siliceous rocks, massive argillaceous siliceous rocks and siliceous shales in Liujiang group has intensively studied. The distribution of siliceous rocks in carboniferous formation is relatively limited, and only has a small amount of chert developed in limestone and dolomile in Huanglong group of central Hunan province and Laohudong group of southern Anhui province. Siliceous Rocks of Permian is extremely developed, and can be divided into two calegories, chert nodules and stripes are widely distributed in the limestone of carbonate platform, in the lower Yangze area they are mostly distributed in Qixia group and Longtang group, and in the upper Yangze area they are mostly distributed in Qixia group, Maokou group and Wujiaping group; there are more layered siliceous rocks distributed in the internal platform basin, in the lower Yangze area radiolarian and spongy siliceous rocks are mostly distributed in Gufeng, Yinping and Dalong group, and in the upper Yangze area black siliceous rocks and carbonaceous shales and event sedimentary clay rocks mostly intergrowth in Maokou group and Wujiaping group. Both contemporanceous fault and volcanism were widely developed in the upper Yangze area, and they were continued from Maokou group to Changing group, making siliceous sediments strongly influenced by hot water; Permian ascending fluid was extensive developed in the lower Yangze area, the nutrient ascending fluid can promote the siliceous and calcareous organisms mass-production in basin and internal platform, forming ascending fluid–siliceous biological prosperous sedimentation model.