Caledonian Structural Characteristics and Dynamics in South China
|School||Ocean University of China|
|Keywords||Caledonian movement Nappe squeeze Fold Intracontinental orogeny Hedge V-belt Ancient reservoirs|
In this paper, the South China region, including early Paleozoic strata are well exposed and typical Caledonian movement through the system anatomy Yuanbaoshan, Guangxi Yuechengling Damingshan, Dayaoshan Region Southeast Guizhou Sandu, Hunan Lianyuan Hunan-Jiangxi border territory and other regions, the use of a comprehensive analysis of field geological survey, indoor geological and geophysical data interpretation method of combining its folds, fracture morphology, formation angle unconformity outputs law of the spatial and temporal distribution and magmatic rocks a detailed description and analysis, and ultimately come to the following conclusions and understanding of: 1) identified the Caledonian deformation exists in two acts: the Caledonian the overall tectonic line early for nearly EW, today outcrop NE - NNE to Lower Paleozoic fold is a result of post-transformation. Xuefeng the Shanxi edge by the Caledonian movement is weak, the the deformation mechanism similar to the Micangshan region, formed the leading edge of the orogen foreland basin, just time difference. The western boundary of the Caledonian movement Xiushui - of Yuanling - Chenxi - three line. 2) analysis of the deformation properties of Caledonian intracontinental deformation: Caledonian granite and sedimentary paleogeography data analysis that China Caledonian orogeny the intracontinental orogeny nature instead predecessors said the ocean - continent subduction events and continent - continent collision events. 3) the the Caledonian deformation mechanism is intracontinental block aggregation: the Caledonian movement of early, Yunkai Block north and Guangxi-Yunnan - NV Block occurred nappe squeeze, makes Guangxi Damingshan. Dayaoshan The areas closed nearly EW Cambrian emergence of wrinkles. This movement the Guangxi-Yunnan - NV Block northward convergence squeezing and the Yangtze block, while the northern margin of the Yangtze Block also began to be the Qinling microplate expansion force, affected by both dual force nearly EW-relief fold form within the Yangtze Block from south to north, the deformation intensity gradually weakened. Late Caledonian movement Yangtze Block China block contraction squeeze by the compressive stress from SE to NW Yangtze block, so in northern Guangxi Yuechengling, Yuanbaoshan, Hunan-Jiangxi border areas as well as Xuefeng Shandong margin area some NE - NNE Lower Paleozoic fold, the early EW trending structural superposition transformation, the deformation intensity gradually weakened from east to west. Meanwhile, the influence of this movement formed in the South China distribution of a large number of planar Caledonian S-type granites, and Yunkai tectonic - magmatic thermal event. 4) to fix the the Caledonian thrust system: at the Xuefeng Mountain East edge, Jingzhou - Xupu fracture, Sanjiang - melt water breaking, Longsheng - YongFu fault performance for the west-dipping the nature Dongchong, while the east side The City steps - Xinhua fracture performance East to pour Nishioki the nature, formation hedge V-belt structure. Locally some west-dipping axial plane in East down the Lower Paleozoic fold, may be subject to recoil constructed Xuefeng mountain barrier formed. 5) discusses the relationship between the Caledonian tectonic and reservoir storage: Caledonian ancient reservoirs are mainly concentrated in the Xuefeng Mountain uplift the western margin of the source rocks are mainly derived from the Lower Cambrian and Lower Silurian, early reservoir formation in The Caledonian, formed in the late in the Indo-Chinese - Early Yanshanian. The Late Yanshanian - Himalayan period is the period of major disruptions of oil and gas reservoirs. Edge of the existing oil and gas palaeohigh less likely, and the oil and gas reservoir more likely to be found in areas far away from the uplift and erosion formation thickness and small, save favorable.