Secondary faulting plays a key role in regulating the Cenozoic crustal deformation in the northeastern Qinghai‐Tibet Plateau

Abstract

In this study, channel steepness and main divide migration analysis were conducted on the Qinghai Nanshan to confirm the activity and evolution of the range. The results showed that the broad and gently dipping northern limbs correspond to relatively low steepness values, while the narrow and steeply dipping southern limbs are characterized by higher steepness distribution. In addition, main divide of the range is currently stable, despite its tendency migrating northward. Based on previous numerical simulations and our geomorphological results, we suggested that the Qinghai Nanshan thrust Fault is tectonically active. The sustained thrust activities of the fault have uplifted the Qinghai Nanshan, driven southward migration of the main divide and caused obvious regional crustal shortening and thickening. Given the same landscape characteristics as the Qinghai Nanshan, the Gonghe Nanshan was found to have appreciable influence on regional crust deformation. Secondary active tectonics (e.g. the Qinghai Nanshan and Gonghe Nanshan) could subdivide rigid blocks into smaller ones and promote the slip transferring and strain regulation between boundary strike‐slip faults. In summary, we concluded that continuous crustal deformation within the northeastern Qinghai‐Tibet Plateau is implemented through strain assimilation by minor faults in minor blocks.

Introduction to the special issue “Tibetan tectonics and its effect on the long‐term evolution of climate, vegetation and environment”

“…The numerical modelling study of Pei et al (2021) investigates the arcuate structure and relates the formation of arcuate structure to lateral heterogeneities related to pre‐existing strong blocks and varying sediment strata thickness and fault geometry. Su et al (2022) utilize geomorphological methods to reveal the activity of the Qinghai Nanshan blind thrust. This study suggests that secondary faulting within the northeastern Tibetan Plateau may play a key role in regulating Cenozoic regional crustal deformation. The Tianshan is located >2000 km away from Indus–Tsangpo suture zone where the Indian and Asian continents first collided, but it has accommodated a substantial portion of India–Asia convergence.…”