Late Cenozoic pollen concentration in the western Qaidam Basin, northern Tibetan Plateau, and its significance for paleoclimate and tectonics

Abstract Pollen concentration (PC) has rarely been used to assess long-term paleoclimate (for example over the Miocene period), vegetation production, sedimentary environment or other factors, particularly for the Tibetan Plateau. In the western Qaidam Basin, on the northern Tibetan Plateau, PCs covering the period ~ 18–5 million years ago (Ma) were calculated and interpreted in terms of the underlying driving forces. The results show that the PCs of the most xerophytic taxa remained stable, while all coniferous taxa decreased during ~ 18–10 Ma. We attribute this phenomenon to continuous aridification, and argue that global cooling played a key role. During ~ 10–5 Ma, the PCs of all taxa increased rapidly, which is contradictory to the continuous aridification after 10 Ma in the western Qaidam Basin. The Tibetan Plateau tectonics around ~ 10–5 Ma caused a change in the sedimentary environment and consequently played an important role in the increase in PCs after 10 Ma. Thus the PC can be a useful proxy for investigations into long-term paleoclimate and tectonics on the Tibetan Plateau.