| The research area is located in the Tethys Sanjiang orogenic belt. Important parts of the region is to study the structural characteristics of the Eastern Tethys tectonic domain structure and the formation and evolution, but also the world of one of the ideal location for Mega orogenic belt. Therefore, the study of structural characteristics and tectonic evolution of the region is of great theoretical and practical significance.Based on the concept of plate tectonics and continental dynamics research-led academic thinking, with an emphasis on structural geology within the research area, combined with sedimentary Petrology, stratigraphy and integrated research approach, identify geological features in the area, combining characteristics and control of the formation, and so on. Detailed study of structural elements of the area breaks, folds and other lineation, foliation, etc., to identify the faults, folds, tectonic geometry, kinematics characteristics. Structural framework of the current analysis of the mechanical mechanism, so as to explore the evolution of structure.The research area belongs to the tectonic unit on the body between the Gondwana and Laurasia, Himalaya tectonic belt(domain) of the southeastern margin of the western margin of the Yangtze island arc basin system of Lancang River orogenic belt and the boundary of the Changdu-Simao basin, North East of Lanping-Simao foreland basin, South West of the Lancang River orogenic belt orogenic belt, Lancang River from the research area near the west side through from west to east across the Gangdise Nyainqentanglha fold system, Fugong, Zhenkang fold belt, the Changning- Menglian fold belt, the Changdu- Lanping- Lanping- Simao fold system and Yangtze paraplatform in Simao depression of Lijiang platform edge fold belt.The formation stratigraphy in the research area for the South China region-Lanping- Simao stratigraphic area- Jinggu- Yangbi district. Acidic magmatism in the region west of the Lancang River fault zone is more intense, Ayi Zhai granite and marble rock Street dikes intrude on the Lancang Orogen Chongshan group ancient metamorphic rocks. East of the Lancang River in Lanping basin range weak magmatic activity in research area, only a few sporadic distribution of mafic dikes, lamprophyre veins.The research area is located in the foreland thrust- slipping belt, located in the foreland thrust belt east of the region, namely water vent- Goujie River fracture(F7) east Goujie, Jijie, Xiyao area sites, the overall structure of the line for NNW-NW direction, but in the south Xiyao sites vary widely, from NW to turn nearly EW, may be affected by the regional tectonic Lancang River "S" shaped bending related. In addition to the NW structure, NE structure is developed, the NE fault in large scale, but its low density, formed later, right lateral cut wrong other constructs, NE to fold in development of location of the change, divided by tectonic line direction, there is NNW-NW direction, NE direction and EW direction.Foreland thrust- slip with Heihui River fracture(f7-16), Xinmin fracture(f7-28) for the sector further divided Conggang fragments、Lailongzuo fragments and Wuyin Hill fragments. Boundary deformation fracture fragments strongly, and has controlled features. Xiyao and its southern area, there is a second nappe structure –Xiyao EW direction nappe structure, a convex northward thrust fault of the arc, thrust to the from South to North foreland thrust-slip zone. Fracture orientation is different from the region, according to the different trend can be broadly divided into three categories: NNW-NW trending structures, NE trending structures, EW trending structures. Each type of fracture have a lot of the size of the fault component, has chosen some representative faults are described in detail.The research area is located in the Gou River- the Shili fracture(F7) east of the region, the area is dominated by slip deformation, tectonic styles developed ejective folds, mainly for the deformation of Jurassic and Cretaceous strata, the formation of foreland decollement belt. Late Himalayan affected Gonglang arc deformation, Xiyao development EW direction from north to south of the overthrust structure. Affected fold structure of the study area is more developed, select some representative described folds, such as: Heihui River anticline ⑤, the village of Zongjia syncline ⑧ and Xinmin syncline ⑨ etc., analyzed its characteristics.According to a comprehensive analysis of sedimentary, magmatic activity, metamorphism and deformation characteristics of the research area is divided into three nappe tectonic evolution: Indosinian period, Yanshan period and Himalaya period. The study area of nappe structure in Indosinian collisional orogeny in Changning – Menglian ocean basin closed. In the Indosinian period it formed the prototype of the central nappe belt, Yanshan period nappe structure began to expand inside the basin, Himalaya early period laid the tectonic pattern of the nappe structure. The nappe structure in the three stage of deformation can be seen in the southwestern margin of Lanping basin, extension of nappe structure for expansion, from within the magmatic arc to the basin, tectonic activity time gradually, deformation intensity gradually weakened, the fault(thrust) deformation is starring into folds(detachment) deformation.Structure formation and evolution of the research area is closely related to the formation and evolution of the Neo-Tethys. Scale ranging from fold to 29 NNW-NW direction of this region were structural analysis, and seek σ1 is 56 ° 3 ’(236 ° 3’), σ2 of 326 ° 11 ’(146 ° 11’), σ3 to 315 ° 16 ’, that is squeezing the tectonic stress field NEE-SWW direction, also on behalf of the direction of nappe structure in the region, and for the lateral compression type. The stress field from the Indian plate lateral compression.The research area has experienced a long history of the development of the geological structure, the occurrence of excessive deformation metamorphism, tectonic pattern of several major changes. This article on the plate tectonic theory, through field investigation and systematic summary of previous literature, the tectonic pattern of Gut Tis ocean subduction stage as the main reference system, and considering the structure of today’s results, the study area was divided into tectonic units. Based on regional tectonics, sedimentation, magmatism, metamorphism and isotopic age, through a comprehensive and in-depth structural analysis, especially cutting and restricted superposition relations between geological structure, according to the process of development and evolution Paleotethyan as the main line, the tectonic evolution of the area initially divided into six phases: The first phase- the base formation stage, ancient- Mesoproterozoic metamorphic crystalline basement formed, it gradually cracking, opened the prelude to the evolution of the proto Tethyan geology; The second stage- Variscan stage, expansion in the Hercynian stage Changning- Menglian basin, led to the extension and subduction; The third stage of Indosinian stage, a series of geological action of collision orogenic process; The fourth stage- Yanshan, Simao- Lanping basin formation; The fifth stage- Himalayan early- the stage and the sixth stage- Himalayan late stage, Himalaya stage inland orogeny. |
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