Permian And Fusulinds Fauna Of Nortern Qiangtang Area, Tibet

Study area is located in Qiangtang central uplift. It is divided into southern Qiangtang strata and Northern Qiangtang strata by the Longmucuo-Shuanghu plate structure zone.The main body of the material was collected by author who attended field geological work in Tibet and we measured there Permian stratum section. A lot of fossil specimens were collected in Tibet. The lower and middle Permian stratum which contains fossils were found first time in Northern Qiangtang area.The Permian stratum division and contrast of northern Qiangtang have been done by he researching in field and indoors geological works ,and describe the fusulinds which contained in the Permian stratum. According the distributing and ranges of the fusulinds, the Permian stratum is compared with South China.Permian sequence of northern Qiangtang area can be divided into three formations lithostragraphically after analysis, respectively Changshehu Formation, Xueyuanhe Formation and Raggyorcak Formation in ascending order. Three Formations interact conformly. Xueyuanhe Formation is composed mainly of gray thick-bedded limestone, bioclastic Limestone, psammitic limestone which clipped sand flag and siltstone. It contains Robustoschwagerina,Sphaeroschwagerina,Schwagerina,Schubertella, Boultonia and coral fossils, brachiopod fossils. Xueyuanhe formation is composed of the light gray limestone which clipped thin slate, micritic limestone, sand limestone and biocalcarenite, it contains Schwagerina ,Parafusulina , Pseudofusulina , Neoschwagerina , Verbeekina , Sumatrina ,Afghanella,Chusenella,Nankinella and frachiopod fauna. Raggyorcaka formation component tripartite: in lower part, the stratum is composed by the micrite, silt shale rock, in middle part ,it can be find the sandstone and biocalcarenite witch contains Palaeofusilina sinesis, Gallewayinella,Reichelina, in upper part, the stratum is composed by the medium-bedded detritus sandstone, sandstones, shale rock and shed coal which contains phytolite Gigantonoclea,Cladophlebis,Anularia,Lobatannularia,Gigantopteris.The early and middle Permian fusulind are found in the northern Qiangtang area first. The early and middle Permian fusulinds are character by the high computerization and abundance. The late Permian fusulinds are becoming specialization and high quantities. Permian fusulinds can be builded into five zones, they are 1,Robustoschwagerina - Sphaeroschwagerina zone, 2,Parafusulina zone, 3, Neoschwagerina-Verbeekina zone,4, Gallowayinella zone,5, Palaeofusulina zone witch can be divided into two subzone 1) Palaeofusulina minima subzone,2) P.sciensis subzone. This five fossil can contrast to typical region in the South China. It can be conferred that the northern Qiangtang area is same to the south China in the paleogeographical Elements.Permian stratum and fusulinds evolution sequence are set up first time by the analysis. It not only perfected the evolution of paleogeographical and tectonic movement in the area but also provided the new information to the research of the recognition of the northern boundary of Gondwanaland and the closure of the paleo-Tethys.