| Abstract: |
Southwest Tibet, which characterized as clean sky, water and grassland as well as head place of several rivers and mountains in south Asia, plays as a crucial role in the protection of the ecological environment and biodiversity in south Asia and even the whole world. Energy shortage constantly obsesses this area for clean energy, such as the solar energy and wind energy cannot be used as uninterrupted energy supply. Geothermal spots widely distribute in southwest Tibet. However, poor prospecting always leads failure in utilization. A success case history of mapping the geothermal system using Audio Magnetotellurics(AMT) and Magnetotellurics (MT) in SW Tibet is presented in this paper. AMT with a frequency range of 11.5-11500Hz was used for mapping the upper geothermal reservoir up to a depth of 1000m, and MT(0.001-320Hz) was sued to mapping the source, pathway and lower(with a depth of larger than 1000m) geothermal reservoir. Data Acquisition Unit developed by Champion Geophysics(Hunan, China) was used for field data acquisition. Featured as lower resistivity than the wall rocks, the heat source, the pathway and geothermal reservoir is clearly outlined by the 3D resistivity data volume converted from the impedance results which was extracted from time series of orthogonal electric and magnetic component of magnetotelluric field. The geothermal model was concept based on the AMT and MT result, and it indicates that the heat source has a buried depth of less than 5km, which might spark the geothermal and fundamental geology research in this area. |