The Geological Characteristics,Age And Tectonic Environment Studies About Gouli Volcanic Rocks Of Early Paleozoic In East Segment Of East Kunlun Orogen

The evolution of the East Kunlun orogenic belt has a long history,is a composite of continental orogenic belts,including a number of important tectonic suture zone.In the thesis,regard the modern plate tectonics theory as guiding ideology,based on the practice of geology,mainly to volcanic rocks detailed geological features,geochemistry and zircon LA-ICP-MS U-Pb isotopic chronology methods about Longwakalu,the west of Zhiyu and the south of Shanjinkuangye in Gouli,combined with regional geological background for the formation age,petrogenesis,tectonic setting and evolution in early Paleozoic of east seation of East Kunlun,which provided crucial significance to study of the Central Orogenic System and the plate tectonic pattern of the Eastern Tethyan tectonic domain, as well as reconstruction of its evolution process since the early Paleozoic.At the same time,some advances and preliminary congnitions are proposed as follows.1、Rock tyres of Longwakalu volcanic rocks is mainly metamorphic basic volcanic rocks(metamorphic basalt)and a small amount of metamorphic andesite,which are low metamorphic degree.By geochemical analysis to obtain metamorphic basic volcanic rocks belong to theoilitic series,and show both IAT and MORB geochemical characteristics,They were derived from enrichment mantle,Which are the results of pyrolite partial melting,formed in the back arc basin tectonic environment caused by the subduction,and obtained that the metamorphic basalt age is 442.0±5.4Ma,belong to middle stage of earlist Silurian.The age concomitant with determines the volcanic rocks of carbonate rocks are different era.2、Make sure the west of Zhiyu volcanic rocks is mainly metamorphic basalt,which are low metamorphic degree.By geochemical analysis to obtain metamorphic basic volcanic rocks belong to theoilitic series.It is similar to Longwakalu volcanic rocks in rare earth elements and trace elements,formed in the back arc basin tectonic environment caused by the subduction.Through the rock combination and tectonic environment,contrast with the regional stratigraphic,The author of the article believes its belong to Naij Tal Group.3、Make sure the the south of Shanjinkuangye volcanic rocks tyres are metaandesite and metadacite,which are relatively high degree of metamorphism.By geochemical analysis to obtain its LREE enrichment degree is much higher than metamorphic basalt. The metamorphic volcanic rocks are characterized by high content in LILE and low content in HFSE Nb、Ta,which is similar to island arc setting and forming crust-mantle mixing action.Through isotope age from predecessors,contrast with rock combination and regional stratigraphic,The author of the article believes its belong to Naij Tal Group.4、Combined with the above study fruites and regional geological setting,East Kunlun region in a split and formed a large area of volcanic rocks in the late Neoproterozoic,There emerges the Proto-Teyhys ocean crust in the Early Cambrian,and subducts northward in the Middle Cambrian,with the strength of subduction,forms the back-arc basin represented by the Qingshuiquan-Kekesha-Kekekete ophiolite,simultaneously forms Nachitai Group and Longwakalu volcanic rocks series.It all developed into collision orogeny in the Middle to Late Silurian after subduction orogeny.Helegangnaren granite shows that the post-collision event takes place in the Late Silurian. Maoniushan Formation indicated that the evolution of the Proto-Teyhys ocean completely over.