The Subduction Geometry and Tectonic Coupling along the Southern Margin of Tibetan Plateau

The India-Asia collision generated a series of north - south trending grabens and rifts in southern Tibetan Plateau, which are closely related to the subduction geometry and tectonic coupling. Also, the tectonic coupling and the fluid distribution in the subduction interface play a significant role in the formation of seismogenic zone. Since the crust beneath the southern margin of Tibetan Plateau tends to be electrically resistive, it is possible to obtain the deeper electrical structure of the lithosphere to better study the subduction geometry and tectonic coupling. Located in the eastern part of the southern Tibetan Plateau, the formation ages of Cona - Oiga Rift, Yadong - Gulu Rift and Pumqu - Xianza Rift are relatively younger. We deployed a new magnetotelluric array covering these three rifts in the southern margin of Tibetan Plateau and derived high resolution three-dimensional electrical model and rheological structure of the lithosphere. Combined with other geophysical and geological results on the southern side of Himalaya, this result will provide new constraint for the extension mechanism and the potential seimogenic zone from the perspective of electrical properties.

Key words: southern Tibetan Plateau, subduction geometry, tectonic coupling, fluid distribution, magnetotelluric

Acknowledgments: This work is granted by the Natural Science Foundation of China (Grant No. 41804075), IGGE Surplus Funds for Scientific Research Projects (Grant No. JY201904), Engineering Innovation and Application for Geophysical and Geochemical Detection Technology (Grant No. AP201901).