| Lanping basin is located in the southwestern margin of the middle eastern Tethyan domains between Gondwana and Laurasia, is a huge part of the Tethyan tectonic domain southeast section of southwest Sanjiang orogenic belt, the geological structure is extremely complex, experienced late Paleozoic- Mesozoic Tethys evolution, Baoshan micro land mass and Chongshan- Lincang plots, Changdu-Lanping plots collide collage and long-term land within the converging action-including the lithosphere contraction, stretching effect, pan role, thrusting action and hierarchical role fold away, and is accompanied by structural- sedimentary, magmatic, metamorphic, mineralization of long-term evolution of complex orogenic belt formed.During the Indo-motion, with the subduction of the Indian plate to the Eurasian plate, the Changning- Menglian ocean basin closure, Yangtze block edge collided orogeny, the southwestern margin of the Lanping block began to form nappe structure. After Yanshan, Himalayan tectonic movement, the southwestern margin of the Lanping basin formed nappe tectonic framework. Temporal and spatial variation in the study area in order to understand the nappe structure and the coupling between orogenic belt and adjacent sedimentary basin of the region, the paper comprehensive understanding of basic nappe tectonic deformation characteristics on the basis of the nappe structure striping analysis of each push nappe belt deformation characteristics, discusses the kinematics and dynamics of nappe structure; By Lanping basin sediments detrital zircon geochronology, fission, sedimentary characteristics, tectonic sedimentation characteristics track time, explore the coupling and the process of nappe uplifting between the Lancang orogenic belt and Lanping basin. Reached the following conclusions:1 According to a combination of style and tectonic deformation characteristics, the middle of southwest of Lanping basin margin of the nappe structure can be divided into the central nappe belt, foreland thrust belt, foreland thrust- slipping belt.2 With a prototype of the central nappe formation in Triassic, which continued into the Himalayan tectonic activity, and a large area of magmatism and uplift substantial return as the main feature; forming a foreland thrust belt during Yanshan and Himalayan tectonic activity continued to form a series of thrust structure and recoil structure; foreland slip band formed in the Himalayan deformation features to kicker folds mainly brittle thrust supplement. Nappe structure after indosian, Yanshan tectonic deformation, and to form the Himalayan tectonic framework today.3 The middle of the southwestern margin of the basin Lanping nappe tectonic extension for pre-show style. From time to magmatic arc basin interior, in turn Oligocene tectonic activity, deformation intensity gradually weakened by fracture(thrust) deformation in the evolution of folds(slippage) deformation based.4 Lancang Orogen different periods plates role in controlling the Lanping basin sedimentary fill their characteristics at different times, in different periods of the basin sedimentary characteristics are also reflected in the record of the orogeny of Lancang orogenic belt.5 Indosinian, Changning- Menglian oceanic closed, Ophiolite, Changning arc granite, Chongshan group and Western Union group provide material source basin. During the deposition of the early T3 m, transgression occurred in the foreland basin, so that part of Orogen sediment supply area submerged beneath the water. The subsidence rate of Lanping basin is relatively slow, and there is no comparison Lancang Orogen substantial uplift occurred. Reflecting slower Indian plate with the Eurasian plate subduction, subduction and collision weak, and thus did not cause a significant uplift of the land-area, the corresponding weathering also relatively weak.6 Yanshan, Orogen belt are uplift rapidly, and the sea exit. Global warming, with hot, dry climates mainly and red continental sediments deposited. Starting from middle Jurassic, Lanping basin has experienced several rapid deposition process filled with alternating slow deposition, while the Lancang orogenic belt had several steady alternating fast and slow uplift.7 Himalayan, the central of Nappe in the early uplift rate is high, the late uplift rate is low, below different style uplift. Uplift foreland thrust belts Miocene uplift also has a multi-stage, and the first is the different style uplift uplifting, uplifting thereafter as a whole. Foreland thrust- slip with uplift is basically different type of uplift, but foreland thrust- slip with late basically in a stable period, and foreland thrust belt is extremely rapid uplift.8 The coupling of the Lancang River orogenic belt and Lanping basin reflects the complexity of the plate tectonic evolution between the Indian plate and Eurasian plate. Due to the strong collision between the Indian plate and the Eurasian plate, causing intense orogeny orogenic belt of Lancang River, the west side of the basin so that the original source of uplift with erosion become Lancang Orogen foreland thrust belt. Construction loads cause the red block body Lanping basin lithospheric flexural subsidence, while the mountain due to continued strong uplift and suffered intense weathering provides ample source material for sedimentary basin, so that rapid sedimentation basin constantly and rapidly development and evolution of the filling process. |
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