Research Of Miocene Epoch Continental Facies Stratigraphy In The Hinterland Of Tibet Plateau

Research region of the thesis south to the Cuoqin basin, north to the Kunlun mountain, the geographical distribution scope is N30-36 , E80-95 and the studying area is 3.0 X 105 km2. The point part of thesis is Wudaoliang Group in the Hoh Xil basin, at the same time , the thesis studied Suonahu formation in the Northern Qiangtang basin and Cuoqin basin.The Hoh Xil basin and the Northern Qiangtang basin and Cuoqin basin ,which lying in the hiterland of the Tibet Plateau, are the main subject of the research reported here. The Miocene Epoch continental facies stratum including Wudaoliang Group and Suonahu Formation, which are the research object. The lithostratigraphy, petrology, sedimentary facies, Epoch of sedimentary have been studied. The information aim at studying tentativly the sedimentary environment and climate characteristic of the Miocene Epoch in the hinterland and the uplift history of the Tibet Plateau.The thesis analysises the typical model profile and the special rock profile of Wudaoliang Group of Miocene Epoch in Hoh Xil basin. And be used the biocalcarenite with the marl rock take the marker bed of Wudaoliang Group. Synthesizely contrasted the Suonahu Formation profile of the Northern Qiangtang basin and Cuoqin basin of Miocene Epoch, used the intraclast ash rock as the marker bed of the Suonahu Formation.Based on the data of the volcanic rock age, fossil age and ESR age detailedly studies the time series of the accumulates of the Wudaoliang Group of the Miocene Epoch continental facies stratum in hinterland of the Tibet Plateau. The volcanic rock age and the age of the Qiangtang Formation determined the Wudaoliang group between 20-5Ma, discovering a flood of spore and pollen with ostracods fossils( regard Eucypris as principle), which are Miocene Epoches typical numerator, therefore Wudaoliang Group accumulate in Miocene Epoch is doubtless;9-2Ma are the age of the Suonahu Formation based on the data of the ESR, which were characteristic of later period in Miocene Epoch - Pliocene Epoch, spore and pollen with fossil all were Miocene Epoch period. Therefore, the thesis thinks Wudaoliang Group and Suonahu Formation are the outcome of the Miocene Epoch.Wudaoliang Group is grayish-white, yellow- grey, dark-grey ash rock, which interbeded with the conglomerate, sandstone, a little amount mudstone, oil shale with unconsolidated sand mud rock. Light gray, light yellow gray carbonate rock, clastic rock, a little amount mudstone with the gypsum rock in Suonahu Formation, regarding carbonate rock as principle.The microfacies of carbonate rock of the Wudaoliang Group in Hoh Xil basin is divided for marl lithofacies, micrite facies, micrite (spar) scraps ash lithofacies, grain scraps micrite facies, dolimite rock lithofacies, and the stromatolite ash lithofacies. The Northern Qiangtang basin Suonahu Formation microfacies of carbonate rock is divided for the intraclast ash lithofacies, biological detritus ash lithofacies, oncolite limestone lithofacies, contain the calcium and alga ash lithofacies, marl lithofacies and pure microlite limestone lithofacies. The microfacies characteristic of carbonate rock of Suonahu Formation in Cuoqinin basin constitutes with the marl lithofacies , the intraclast ash lithofacies, biological detritus ash lithofacies.Analyses and researches systematically the facies and depositional environment of Miocene Epoch Wudaoliang Group in Hoh Xil basin in hinterland of the Tibet Plateau . Dividing the sedimentary facies as a delta- lacustrine facies according to Wudaoliang Group sedimentary rock facies and its combination, regarding lacustrine facies as principle; The Northern Qiangtang Suonahu Formation sedimentary facies was divided for fluvial facies and the lacustrine facies, regarding lacustrine facies as principle. The Cuoqin basin Suonahu Formation is lacustrine facies and been divided into fan-delta and shallow lagoon facies.The thesis puts forward the Miocene Epoch of hinterland of Tibet plateau being a big lake, forming lacustrine facies of the Wudaolia...