Three-Dimensional Crustal Channel Flows Beneath the Southeastern Tibetan Plateau Revealed by Full-Waveform Ambient Noise Tomographys

Abstract

The growth process of the southeastern Tibetan Plateau remains a fundamental yet unresolved question. Knowledge of detailed lithospheric structures and their potential linkages with surface features offers crucial insights. Here, we present a high-resolution 3-D lithospheric velocity model of the southeastern Tibetan Plateau using full-waveform ambient noise tomography. Our model reveals two prominent low-velocity anomalies within the middle and lower crust with new characteristics in spatial distribution: Anomaly 1 lies beneath the plateau, and Anomaly 2 beneath the craton has two branches aligning with the Sichuan-Youjiang tectonic boundary and the eastern margin of the Emeishan igneous province. Furthermore, these two anomalies appear interconnected at deep crust beneath the northern margin of the Emeishan igneous province. We propose that observed crustal velocity lows indicate partially melted materials transported from the high plateau into the cratonic crust along pre-existing weak zones, which were reactivated during recent continental deformation.