| Electrical characteristics of rock and a geoelectric model were set up based on the total 24 sites of 26 magnetotelluric (MT) surveying lines that were laid in Youjiang Faulted Sag of Nanpanjiang depression in 2001.Tracking a major structural layers and faults in this region reveals the 3-D elevation configuration of the Triassic,Carboniferous-Permian and Devonian bottoms. The result shows that MT is an effective way to study regional or local structure. There are 11 main faults with relevance to geologic structures that are all thrust faults, which most are NW-NWW-trending,10～100km extensional, 50°～60°southward-dipping structures with synsedimentary feature. Main MT synclines, including Xiaohekou, Bagui, Yangbian and Xiping synclines, are all congruous with geophysical results in the sag. The structural amplitudes are at 850～1400m for the Triassic bottom,1 000～1 750m forCarboniferous-Permian bottom and 1 500～2 500m for Devonian bottom. Distribution of the region also has more than 10 exposed or concealed anticlines and heaves. This result indicates that the geologic structures are complex in the whole region, especially in Youjiang Faulted Sag. |
