The Study Of Magnetic Structure Over Xuefeng Tectonic Belt And Its Adjacent Areas

The Yangtze block is not only the main tectonic unit in Southern China, but also an important area about exploration of marine oil and gas resources. Xuefeng tectonic belt is located in the southeast edge of Yangtze Block, which the study of its structure is great significance to explore the formation and evolution of the entire Yangtze block.In this thesis, the aim is to research basement structure, the coupling/decoupling relation between the basement and its cover layers by multi-processing and analysis of the satellite and aeromagnetic anomalies, which provides geological-geophysical evidences for the exploration of marine oil and gas. Firstly, the satellite magnetic anomalies, reflecting the features of the lithosphere magnetic field have been computed and explained. And then, reducing to the pole for AT anomalies and the corresponding potential field conversion processes of the aeromagnetic data have been done. The regional magnetic characteristics and the faults distribution have been analyzed. Further, the profiles of aeromagnetic data are inversed using Euler deconvolution inversion method and are fitted using the 2D magnetic model. Finally, combination with surface geological, petroleum seismic profiles, MT and other information, the characteristics of the basement structure, the deep border of the Xuefeng uplift, the natures of the main faults and the problems of the Chishui EW structure in Guizhou province (along 28°north latitude) to the eastward extension are discussed.The basement magnetization of the Xuefeng uplift, being different from Sichuan basin, is weak and segmentation along strike. A comparison with the deep and shallow features of anomalies suggests the decoupling relation between the surface geological and basement structure over fault-fold zone of Sichuan-Guizhou. The Chishui EW strike structure within basement extends eastward to Lianyuan in Hunan province, which extends probably down to middle-lower crust. Xuefeng uplift is a huge and multi-stage old one. As a whole, the uplift represents a positive flower-shape structure resulting from multi-stage strike-slip, NW and SE thrust respectively.