Study On The Deep Magnetic Structure Of Ultra-high-pressure Metamorphic Belt In Sulu Area

Research on lithosphere is the forward position of the contemporary geosciences. The data of geophysics, petrology and geology are integrated to study the deep magnetic structure of the ultra-high-pressure metamorphic belt in Sulu. The intensive dynamic processes which have occurred after the collision between the Sino-Korean and Yangtze cratons are discussed based on the study.In this study, three methods (upward-continuation, equivalent source and euler deconvolution) are used to process the aeromagnetic data and satellite magnetic data. The magnetic structure of crust is obtained.According to Jacobsen, the information corresponded to various deep layers can be obtained when the gravity or magnetic data are processed by upward continuation. The property of upper crust can be deduced from the residual anomaly which is got by subtracting the anomaly at 10km from the total anomaly and the anomaly at 30km from the anomaly at 10km. Similarly, subtracting the anomaly at 60km from the anomaly at 30km and the anomaly at 100km from the 60km correspond to the magnetic sources in the middle crust. The large-scale and deep-seated terranes and structures in the lower crust can be interpreted from the satellite magnetic anomaly. Through this method may produce much big error, it is easy to calculate and has clear geophysical principle. It can be a semi-quantative approach.The apparent susceptibility can be received by an equivalent source technique. The spacial distribution of apparent susceptibility is obtained by inversing various scale magnetic anomaly.The depth and horizontal position of magnetic object are estimated by Euler deconvolution. The technique is based on Euler's homogeneity relationship and requires no prior knowledge of the source magnetization direction. It has been widely used in automatic aeromagnetic interpretation.The results are as following:1. According to the characteristic of magnetic anomaly and the distribution of faults, the study aero can be divided into three main tectonic units (Sino-Korean, Sulu orogenic belt and Yangtze...