Tectonic Characteristics And Geological Evolution Of Tibet Lhasa Zetang Area

Lhasa-Zedang region is located in the south-central part of the Qinghai-Xizang Plateau.The northern part of the region is located in the Gangdus-Nianqingtang Gula block,and the southern part is in the Himalayan block,crossing the Brahmaputra confluence zone in the middle.Because of the geological structure evolution of Gangwanagu land since the pan-African movement,the structure(hierarchy,deformation facies,style,assemblage)in this area is complicated and diverse.Because of its complicated geological evolution history,it is an ideal place to study intracontinental convergence,plate movement and plateau uplift.Studies suggest that the region has a "North South zoning" tectonic framework and complex fault system.According to the theory of plate tectonics and activity theory,the test area roughly north to south is divided into gongbujiangda-Zayu fold belt(I 1),Lhasa-Gangdise magmatic arc(I 2),Yalu Zangbo River belt(II),the Kangmar Longzi fold thrust belt(III 1)4 tectonic units,the structural features of each tectonic unit respectively by tectonic deformation facies,dynamics mechanism and control factors of dry rock,the tectonic units in the structural size,structural style,structure combination and so there are some the difference,but the overall performance of structure.To east-west direction,accompanied by north-west,north-east and near-S-N direction.In this paper,through the use of comprehensive stratigraphy,orogenic tectonic geology,magma dynamics,basin mountain coupling,a variety of geophysical and geochemical means,reasonable using the method of mapping and mapping combined with the geological data update,the realization of digital map data of the area,systematic,standardized,determine the structure mechanism and evolution of the area,solve some major geological problems.Further research on construction and transformation of each unit of material,it is established that the sedimentary and deformation sequence of events,and summed up the 4 stages of crustal evolution model,namely continental crust basement formation stage;Paleo Tethys subduction closed after the first stretch.The tectonic evolution stage;new Tethys oceanic basin extension and contraction subduction stage;continental collision and uplift of the plateau stage.Reproduction of the surveyed area since the formation of the Neo Tethys ocean since the late Paleozoic,tectonic evolution and disappearance of evolutionary history.