Cenozoic climate cooling and tibetan plateau uplift jointly drive increased atmospheric dust deposition in Inland East Asia

Abstract

In the Earth system, atmospheric dust plays a crucial role in global climate evolution and biogeochemical cycles. Based on the hypothesis that the average content of inorganic components in coal throughout the regional geological history is mainly supplied by atmospheric dust, the coal ash yield, which serves as a proxy indicator for the inorganic components content in coal, was systematically collected, supplemented with measurements, and comprehensively analyzed for the sedimentary periods of the Eocene (50 Ma) and Miocene (10 Ma) epochs in East Asia. Accordingly, the relative concentration levels and deposition rates of atmospheric dust in East Asia during the Eocene and Miocene epochs were estimated, and their distribution characteristics and patterns were identified. The results indicate that under the driven by specific wind directions, atmospheric dust deposition rates in East Asia during the Eocene and Miocene epochs exhibited a significant negative correlation with distance from arid dust source areas; the concentration level and atmospheric dust deposition rates in East Asia during the Miocene epoch were significantly higher than those during the Eocene epoch, and the high value area is mainly located in the eastern part of the Tibetan Plateau. The analysis suggests that the global trend of cooling after the early to mid-Eocene epoch coincided with the rapid uplift of the Tibetan Plateau to approaching its present level during the Miocene epoch. The combined effects of these changes greatly enhanced the emission and transmission capacity of atmospheric dust, and altered its deposition pathways. This resulted in significant differences in the activity intensity and distribution of atmospheric dust in East Asia during the Eocene and Miocene epochs. The comprehensive analysis indicates that paleogeography and paleoclimate evolution were the primary factors controlling the intensity and distribution of atmospheric dust deposition in East Asia during these periods.