Lithospheric Electrical Structure in the Central Tibetan Plateau revealed by the MT and its significance

The Himalaya-Tibetan Plateau that is situated in the southwest China is an ideal natural field laboratory for continental dynamics. Through the careful processing and analyzing of the magnetotellurics data from the Gangba county in the Tethys-Himalaya to the Longwei Tso in the Qiangtang terrane, the reliable 2-D electrical model was obtained to examine the relationship between the lithospheric electrical structure and dynamics in the central Himalaya-Tibetan Plateau. Six conductors mainly result from the partial melting and aqueous fluids, and three resistors are related to different tectonic evolution in the model.

Combined with other observations of line 800, line 100 line 700 and line 500 (reexamined and remodeld) from INDEPT-MT project, it is summarized that the upwelling hot material (partial melting), aqueous fluids, subduction erosion and crushed zone contribute to the error between the electrical location and the geographic location of the Indus-Yarlung Zangbo suture. The subduction of the Indian plate shows the feature of different angles and different locations of its frontier in different areas. The Lhasa terrane can also be divided into three subterrane based on the lithospheric electrical structure beneath the Lhasa terrane, which also correspond well with the fact of the geological features of an old, locally reworked crust dominantly in the central Lhasa terrane with two young juvenile crustal blocks surrounding the central terrane. Meanwhile, we indicate that the subducted polarity of the Bangong- Nujiang Tethyan Ocean lithosphere was double-sided, and the smooth subduction of the Longmu Tso-Shuanghu Tethyan Ocean lithosphere may cut through the Moho surface approximately 20 km. Furthermore, the electrical structure beneath the Lhasa terrane also shows the relationship among the dynamics, magmatism and mineralization in the Gangdise metallogenic belt. Above all, these results can provide helpful constrains to understand the evolution mechanism of the Himalaya-Tibetan Plateau.

This study is funded by the National Key R&D Program of China (2016YFC0600301), the National Natural Science Foundation of China (41704099) and the fundamental Research Funds for the Central University (18lgpy15).