The nature of the Kumkol Basin, northern margin of Tibetan Plateau constraints from seismic velocity structure

The Kumkol Basin, situated in the northern margin of the Tibetan Plateau, provides a unique window into understanding the dynamic mechanisms driving the plateau’s northern expansion. However, its formation and tectonic evolution remain poorly understood due to limited geophysical data in this region. In this study, we computed cross-correlations for the T-T components of station-pairs with high signal-to-noise ratios to extract Love wave waveforms and further performed Love-wave ambient noise tomography to image the upper crustal shear-wave velocity structure of the Kumkol basin down to 10 km depth. Our seismic velocity model reveals that the Kumkol Basin has a sedimentary thickness exceeding 8 km, with its center located near the Arka Mountain on the southern side. This suggests that the basin was likely formed as a foreland basin in response to the uplift of the Qimantagh Mountain to the north. Additionally, integrated with seismic reflection data, our seismic velocity model images a detachment fault at the basin basement depth. We inferred that the Kumkol Anticlinorium at the basin’s center have been produced by multiple thrust faults converging into this detachment fault at 8–10 km depth following the Early to Middle Miocene uplift of the Qimantagh Mountain. This structural configuration indicates pulsed basinward deformation since the late Miocene, likely reflecting a tectonic regime shift from extrusion to distributed shortening in the northern Tibetan Plateau. Our findings provide a high-resolution velocity model of the Kumkol Basin, offering critical insights into its structural evolution and supporting future resource exploration in this underexplored region.