Geologic Features,provenance Analysis And Structural Evolution Of Naocangjiangou Formation At The In The Southern Slope Of The East Kunlun(East Part)

Sedimentary basins and Orogenic belts are the most important structural unit on the continental crust,their coupling relation is a hot of continental dynamics research.The clastic of sedimentary basin either is the direct evidence of sedimentary basin and tectonic evolution or reflects the link of provenance and sedimentary basins. So studying the clastic of sedimentary basin can restore the sedimentary environment and tectonic setting of the source region of sedimentary basin. This thesis mainly focus on the Naocangjiangzou Formation in Middle Triassic which located in the southern slope of the East Kunlun Orogen,with sedimentary petrology, statistical analysis of detrital composition, geochemistry and zircon geochronology methods to study sedimentary characteristics and structure properties of Naocangjiangzou Formation,recovery tectonic evolution of East Kunlun Orogen which in late Paleozoic- early Mesozoic on the basis of previous. At the same time,some new advances and preliminary cognitions are proposed as follows:1,It divided Naocangjiangzou Formation into two sub-groups from the bottom to the top by the difference formation rock composition and sedimentary environment.The upper sub-groups is clastic rock and a small amount of carbonate rock,the performance of shallow water clastic continental shelf sedimentary environment.The under sub-groups is carbonate rock and a small amount of clastic rock,the performance of shallow marine carbonate platform sedimentary environment. Description at this forearc basin have tended to fill up the momentum, the performance of the sedimentary sequence of shallow depth. It determined deposition times of Naocangjiangzou Formation by Paleontological data, Zircon ages, Kekeealong intruded and the unconformable contact,it is Middle Triassic.2,Naocangjiangzou Formation is Near deposition by petrography.The Dickinson’s Triangle Graphic display the source material is more complex of Naocangjiangzou Formation,the provenance mainly come from the Collisional orogenic belt and Recycled orogen, the little provenance come from Magmatic arc.The construction background of Naocangjiangzou Formation is continental arc by Sandstone geochemistry.3, The study of detrital zircon U-Pb age shows that detrital zircons in sample 11072/15 from Naocangjiangou Formation has 4 age groups including 226~324Ma、372~576Ma、749~936Ma、1010~1092Ma.The under subgroups of the Naocangjiangzou Formation second paragraph of detrital zircon U-Pb age of information to demonstrate strong ditch downtown warehouse sedimentary strata was the main source for the East Kunlun area Proto-Tethys Ocean and the Paleo-Tethys evolution of the form magmatic arc and its complement of sedimentary strata.Combined with regional data and the analysis results are considered strong downtown warehouse Xiagou provenance mainly late Hercynian-Early Indosinian Andean-type continental margin arc,Caledonian magmatic arc is second palce.4,Combined regional information the tectonic evolution of the study area can divide into four evolution stages,oceanic crust formation stage in earl y Carboniferous,oce anic spreading stage from late Carboniferous to middle Permian, the oceanic crust subduction stage from late Permian to middle Triassic,demise of the oceanic basin and collide-to-orogenesis stage at the end of Triassic,Cenozoic intracontinental orogenic stage.