The Regional Tectonic Characteristic And Their Evolution Of Niukong Lvchun Region Yunnan Province

The research area is located in Tethys sanjiang orogenic belt combined with thesoutheastern yangzi landmass. This area is an important area that helps to study thestructural characteristics and the evolution of East Tethys tectonic domain; as well isone of the ideal locations to discuss orogenic belt giant compound all over the world.Thus，there is a great theoretical value and practical significance in the structuralcharacteristics and tectonic evolution of the forelandbasin and thrust belt byresearching this area.On the basis of having knowledge or making progresses about Ailaoshanorogenic belt and adjacent area in general, taking use of tectonic geology with the newtheory and technological method. At the same time, through the field geologicalsurvey and analysis of the area about the strata, rocks, structure and dating data, andother aspects of the research results, it should study structure characteristics of thegeometry kinematic features, structure combination, the characteristics minutely,accordingly, having a preliminary understanding about dynamics mechanism, thencarry on the research on structural evolution of this area.After concluding the research achievements of predecessors, analyzing andorganizing the data of field observations and indoor treatment systematically. As forstructural feature and tectonic evolution in Yunnan Lvchun Niukong area, it can drawsome conclusions as follows.Through combining the field geological survey with regional geologicalbackground, and determined the Lv Chun Niu Kong area is a foreland by the belt, andsay7boundary faults and6fragments. Fragments tectonic deformation charactersdivided into3types mainly: thrust type, fold-type and drape-thrust type. The structurepresent the oriention west-south, and southward from the arc of style, in profile is foldtegular output, fragment, subprime drape fault in subprime development, tectonicdeformation strongly.It can be found that the thrust nappe structure in this area expands from northeastto southwest，which expansion mode is first expansion，by the study of tectonicdeformation，regional geological，crooked middle kingdom groupgravel provenance and Zircon fission track.The nappe structure in this area could date to indosinian, meanwhile form thetype in the Himalayan tectonic movement, which evolution has close relationship withNeo-Tethys. NNE—EW extrudes to the horizontal direction and deforms to theintracontinental after the H imalayan tectonic movement and the Neo-Tethyansubduction collisional orogeny, which as a result of the thrust nappe systemLongmenshan-Jinpingshan-Ailaoshan in the western margin of Yangtze Platform.According to the analysis of regional tectonic，sedimentary，magmatic activity，metamorphism and isotopic age，especially the relationship of cutting，restraint，andsuperposition among geological structure，it can determined that there are threestructural layers，three tectonic facies，three structural level and go through fivetectonic cycles. In summary，the study area developed eight tectonic deformationgenerations.The tectonic evolution in this area can be distributed into three stages. The stagefrom Silurian Period to Early Permian is the developmental stages of passive marginbasins,the stage from the middle Permian to the middle triassic is the developmentperiod of back-arc basin,the stage from the late Triassic to cretaceous isthedevelopment period of arc foreland basin.