Variation characteristics of global atmospheric dust deposition rates during the Paleogene–Neogene periods: A quantitative study based on coal ash yield

Atmospheric dust plays multiple significant roles in the Earth system, and its quantitative data are vital for an in-depth understanding of paleoclimate changes. However, the lack of coal-derived atmospheric dust data from the Paleogene–Neogene periods of the Cenozoic restricts comprehensive research on the paleoclimate system. Based on the hypothesis that the average content of inorganic components in coal throughout regional geological history is primarily supplied by atmospheric dust, this study systematically collected and supplemented measurements of coal ash yield, which serves as a proxy indicator for the content of inorganic components in coal during the Paleogene and Neogene sedimentary periods worldwide, and established a global database of coal ash yield. By applying the long-term rate of carbon accumulation (LORCA) method, global atmospheric dust deposition rates for both periods were estimated, thereby characterizing their spatial-temporal distribution patterns and transport pathways. The results indicate that compared with the Paleogene period, the atmospheric dust emission intensity in the Neogene period was higher and its spatial distribution was more extensive, with its high-value areas mainly concentrated in southeastern East Asia and central–eastern Europe. Driven by prevailing winds (e.g., the westerlies, the northeast trade winds), atmospheric dust deposition rates decreased significantly with increasing distance from arid source areas, and exhibited a clear negative correlation. From the perspective of latitudinal variation, global atmospheric dust deposition rates exhibit an overall increase from the Paleogene to Neogene periods; however, the subtropical belt (20°N–30°N) records an inverted pattern, with Paleogene period atmospheric dust deposition rates exceeding Neogene period values. The analysis suggests that the transition of global temperatures from the Paleogene period greenhouse climate to the Neogene period icehouse climate governs the periodic variations in dust flux. Meanwhile, the continuous movement of global plates (including subduction, collision, and separation) altered regional paleogeomorphology and atmospheric circulation, significantly influencing the spatiotemporal differentiation patterns of atmospheric dust deposition.