Crustal Architecture of Ruo'ergai Basin and Its Implications for Eastern Kunlun Fault Propagation

Since the Miocene, the Tibetan plateau has undergone continuously eastward extrusion, with block velocity disparities principally accommodated by large strike-slip faults, one of which is the active East Kunlun Fault Zone (EKFZ). The quiescence of the EKFZ within the Ruo’ergai Basin (RGB) stands in marked contrast to the rapid uplift of the Minshan Mountains along its eastern margin, rendering the mechanics of east-west stress transfer across the basin a critical research focus. The crustal architecture of the EKFZ region is a critical constraint for elucidating the underlying geodynamic mechanisms. This research delineates a high-resolution crustal architecture across the RGB through P-wave receiver function analysis utilizing a dense short-period seismic array. Our findings reveal crustal decoupling accompanied by progressive Moho depth increases within the basin proper. The spatial extent of the EKFZ has been demarcated based on geophysical constraints, regional strain rates, and crustal geometric attributes from adjacent RGB segments, with its eastward kinematic linkage to the Tazang Fault (TF) within the mid-upper crust systematically identified. Integrating geochronological constraints with present-day kinematic data from the EKFZ, we develop a tectonic evolution framework that resolves the post-late Miocene southward migration of this fault system and its mechanical coupling with peripheral tectonic development.