Neogene evolution of the north-eastern Tibetan Plateau based on sedimentary, paleoclimatic and tectonic evidence

Abstract In this study, the development of the north-eastern Tibetan Plateau is investigated via an integrated study of the sedimentology, magnetostratigraphy, palaeogeography, and cross-section comparisons of the Neogene sedimentary basins of the Tibetan Plateau. From 23 to 17 Ma, this region was characterized by widespread angular unconformities and a sedimentary hiatus, indicating the comprehensive uplift of the plateau. The tectonic event that created the Tibetan Plateau triggered the evolution of sedimentary basins. During the Middle Miocene climatic optimum event, the growing Qilian Shan formed a barrier, leading to cooler and drier conditions on the western side of the mountain. However, humid and warm conditions persisted on the eastern side of the range. After this event, this region was influenced by a global cooling trend and enhanced tectonic activity in the north-eastern Tibetan Plateau. At approximately 10–8 Ma, sedimentary data, which were consistent with low-temperature thermochronological records, indicated the inversion of the surrounding mountains and rapid exhumation of the Laji Shan. Since 5.0–3.6 Ma, these intermontane basins gradually shrank and disappeared due to the overall uplift of the Tibetan Plateau and the accelerated global cooling trend and were associated with unconformities and growth strata that formed during stepwise-north-eastward thrusting tectonism.