Deep electrical characteristics of Mayang Basin，Hunan and its indication to tectonic and geothermal resources

Mayang Basin in Hunan Province is located in the uplift area of Xuefeng Mountain, which is rich in geothermal resources. In order to understand the deep structure of the basin and analyze the source of geothermal resources, we uses the audio magnetotelluric and magnetotelluric profiles collected at the same point in the area to carry out 2D inversion. To ensure the reliability of the final electrical structure, firstly, based on the phase tensor, the qualitative analysis of the observation data, such as dimension discrimination and spindle azimuth statistics, is carried out to determine the tensor impedance rotation angle. Then, the two inversion strategies of adaptive regularization and L−curve regularization are compared. The forward and inversion trial of the simplified model proves that the results obtained by the L−curve strategy are more objective and real, and the electrical structure model of Mayang Basin is obtained by L−curve strategy inversion. Finally, combined with prior geological information, we identify the deep extension of the three faults, and believe that the deep high−resistance uplift area of the Mayang Basin roughly reflects the range of the basin’s crystalline basement uplift. The electrical model obtained by inversion shows that there is a large−scale high−conductivity area in the deep part of Mayang Basin, which is presumed to be partially melted thermal material that transmits heat upward as a deep heat source, and the high−resistance body in the shallow part serves as a caprock, which provides favorable conditions for geothermal preservation. The fracture between the two links the shallow and deep parts. Finally, a hot spring is formed at Mayang County. Our research shows that the belt also has a great prospect of geothermal resources.