Crustal electrical structures and deep processes of the eastern Lhasa terrane in the south Tibetan plateau as revealed by magnetotelluric data

Abstract

A 3D Magnetotelluric (MT) inversion for a 2D broadband MT profile along 92°E in the eastern Lhasa terrane was applied to understand the crustal electrical structures and deep processes in the India–Tibet continental collision zone. The middle and lower (−20 to −50km) crust is distributed with conductors that are primarily concentrated north of the Yarlung–Zangbo sutures (YZS). The results imply that the hypothesis of middle (and/or lower) crustal flow between the Tethyan Himalaya and Lhasa terrane are not supported by the MT data within the profile area. We suggest that given the possibility of the existence of channel flow in the middle (and/or lower) crust extruding southward from Tibet, the southernmost portion should be limited in the northern YZS. The electric model also indicates that the primarily conductive region in the middle to lower crust can be imaged from the YZS to ~30.8°N, while the crust of the northern Lhasa terrane north of ~30.8°N has a higher resistivity. From this result, it can be inferred that the northern Lhasa terrane might have a cold and strong middle to lower crust and that the front of the India crust might be halted in the northern Lhasa terrane (~30.8°N) along 92°E.