A rare record of the early and middle Holocene dust export history of the Mongolian Plateau obtained from a crater lake on its southern boundary

Abstract

The dust export from the interior Mongolian Plateau to downwind regions is key to identifying environmental changes in the source areas of Asian dust and the dust forcing in climate system. Due to the lack of ideal aeolian sediment materials and the imprecise indication ability of grain-size index, dust export from the Mongolian Plateau during the Holocene is still unclear. Diaojiaohaizi Lake is a closed crater lake located at the summit of the Yinshan Mountains, and on the southern boundary of the Mongolian Plateau. Compared with other lakes inside the dust source area or distant downwind areas, the unique location and geographic features make it possible for this lake to record the dust export history of the Mongolian Plateau more directly. Comparing the properties of chemical elements, Sr-Nd isotopes, magnetic minerals, mineral compositions and grain sizes between lake sediments, lakeshore materials and bedrock of Diaojiaohaizi Lake, we deduced that the lake sediments was relatively pure aeolian materials. Therefore, the mass accumulation rate of the lake sediments was further used as an ideal index to indicate the dust export history from the Mongolian Plateau during the Holocene, which had an average deposition of 29.1 g/cm2/ka at ∼ 11500–9200 cal. a BP, decreased to 16.0 g/cm2/ka at ∼ 9200–7400 cal. a BP and decreased sharply to 7.6 g/cm2/ka at ∼ 7400–4000 cal. a BP. This indicates that the dust export activity of the Mongolian Plateau was much stronger in the early Holocene than in the middle Holocene.