Tang, Yingde ， Liu, Fangbin ， Gao, Shibao ， Jin, Yupeng ， Gao, Peng ， Nie, Junsheng
2026-05-15 PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY 2026 690(卷), null(期), (null页)
During late Miocene times, the Qaidam Basin located on the northeastern Tibetan Plateau developed a hyper-arid landscape characterized by brine mineralization. In this paper, we investigate this aridification process by analyzing the uplift history of the Elashan and Qinghai Nanshan (the east-gateway mountains of the Qaidam Basin) using magnetic polarity stratigraphy, anisotropy of magnetic susceptibility, provenance, and environment magnetism from the Chaka Basin to the east and comparing paleoclimate proxies with the eastern Qaidam Basin to the west. Results show these mountains converged and reached a critical elevation during 7.1-5.6 Ma, effectively blocking moisture from the Asian Summer Monsoon. This tectonic closure caused a stark hydroclimatic divergence: enhanced aridity in the Qaidam Basin due to a rain-shadow effect, contrasting with increased precipitation in the windward Chaka Basin. Our findings demonstrate that while global cooling set the stage for late Miocene aridification, regional tectonic uplift was the primary mechanism driving the extreme aridification that defines the Qaidam Basin today.