Application of the homogeneous function and modeling methods for reconstruction of a Tibetan geological section from a travel-time inversion

Abstract

New structures were revealed in Central Tibet after reinterpretation of the first arrivals of refracted seismic waves along the INDEPTH III profile. The method that was used for travel-time inversion is the numerical generalization of the Herglotz-Wiechert formula for the case of a 2D inhomogeneous medium (the homogeneous-function method). The new section shows that the Bangong-Nujiang Suture (BNS) is a contact in the upper crust, while its continuation in the middle crust is a listric thrust; at the top of the lower crust, which has risen to a 32-km depth in the northern part of the section, this thrust become gentler. Below the middle crust top, a layer with a lower velocity of seismic waves is found. The middle crust is deformed and forms oblique southward listric thrusts. In the upper crust south of the BNS, higher-velocity zones (probable zones of magmatism) are distinguished. North of the BNS, undisturbed outlines of the structures are observed.