A Potential Mode of the Lithospheric Growth and Delamination of Orogenic Belts: Evidence From High‐Resolution Magnetotelluric Data

Abstract

The Greater Xing'an Range (GXAR), situated in the eastern segment of the Central Asian Orogenic Belt, is a prominent orogenic belt that offers an ideal opportunity to explore the dynamic processes underlying lithospheric growth and delamination. A two‐dimensional resistivity model was obtained based on a magnetotelluric survey with 110 stations. The results identified a lateral conductor, associated with the asthenosphere, in the overall high‐resistivity lithosphere of the GXAR. This conductor was recognized as the residual trace of the asthenospheric materials upwelling along the reactivated Xinlin‐Xiguitu suture zone, manifested as the precipitation of metasomes/conductive phases or new lithosphere distributed along channels. The transformation of the GXAR, involving the lithospheric accretion and erosion from the interior, suggests a geodynamic process of thick lithospheric delamination. The erosion of asthenospheric materials from the interior of the lithosphere was deemed as a potential mode of the lithospheric growth and delamination of orogenic belts. The discontinuity of lithospheric thickness, the reactivation of paleo‐sutures, and the tectonic environment leading to mantle convection control the occurrence of this mode.