Electrical Structures of the Lithosphere Along the Prydz Belt: Magnetotelluric Study at Chinese Zhongshan Station, East Antarctica

Zhongshan Station (69° 22′24.76 ′′s, 76°22′14.28′′E) is located in the Westoden Peninsula, Larsemann Hills area, Princess Elizabeth Islands, East Antarctica. Here, we report results from a magnetotelluric experiment and delineate the deep electrical conductivity structure beside the Zhongshan Station by using the data acquired during the 36th Chinese Antarctic Scientific Expedition. Magnetotelluric (MT) data have the advantages of wide range and large depth in geophysical surveying. Two-dimensional inversion of MT data was conducted using the nonlinear conjugate gradient algorithm, and the conductivity structure under the Larsemann Hills area was described. The simulation results show that the high resistivity level in the shallow layer represents the Quaternary glacial sediments on the surface of bedrock. Further, the underground electrical structure within the depth of 10 km in the middle section shows obvious horizontal difference and drastic longitudinal variation. The depth of 10–40 km is characterized by thick layer and low resistivity, the electrical structure is relatively uniform, and the low resistivity structure is geographically inclined slightly to the northeast. This section is characterized by low resistivity structure. The upper part of the southwest section is characterized by high resistance, and the middle and deep part (below 10 km) is characterized by relatively uniform and low resistance terranes. The discovery can be interpreted as follows: The low resistivity body in the southwest segment represents the core cratonic crustal structure of the southeast polar shield, while the low resistivity body with complex electrical structure in the middle 10 km depth of the section can be interpreted as the collision zone between the Prydz Orogenic Belt and the East Antarctic craton. Our study confirms the position of the Prydz Orogenic Belt under the Larsemann Hills of East Antarctica and depicts the electrical structure of the collisional amalgamation area, which provides evidence for further study of the splicing of the Gondwana archicontinent.