Crustal Flow Influences the Tectonic Evolution of the Eastern and Southeastern Tibetan Plateau: Insights from Multimodal Ambient Noise Tomography

Authors:
Preprint
Publisher website
Google Scholar
Abstract
The Cenozoic collision and convergence between the Indian and Eurasian plates drove north-south crustal shortening, uplift, and outward growth of the Tibetan Plateau. Since the Late Miocene-Early Pliocene, the plateau has expanded eastward and southeastward, while lateral extrusion, crustal thickening, and surface uplift have jointly shaped its eastern and southeastern margins. Here we collect continuous waveform data from dense seismic arrays in the eastern and southeastern Tibetan Plateau to construct three-dimensional S-wave velocity and radial anisotropy models. We first apply the frequency-Bessel transform (F-J) method to extract multimodal surface wave dispersion curves from ambient noise data, and then invert these measurements using multimodal ambient noise tomography.Our models delineate the detailed three-dimensional geometry of the mid- lower crustal low-velocity zone (LVZ). The spatial distribution of the LVZ shows a close correspondence with regions of pronounced lateral extrusion and crustal deformation. The LVZ also exhibits strong positive radial anisotropy, which provides seismic constraints on possible ductile crustal flow pathways. In addition, variations in LVZ thickness show clear spatial correlations with surface elevation, Moho depth, and present-day GPS velocities. These observations suggest that weak mid-lower crustal materials may play an important role in surface uplift, crustal thickening, and ongoing deformation across the eastern and southeastern Tibetan Plateau. Based on these results, we propose a three-dimensional geodynamic model that explains two contrasting geomorphic end members: the steep eastern margin and the gently sloping southeastern margin of the Tibetan Plateau. This model provides a framework for understanding the tectonic evolution and outward growth of eastern and southeastern Tibet since the late Cenozoic.

This publication has 50 references indexed in Scilit: