Aridification history of the West Kunlun Mountains since the mid-Pleistocene based on sporopollen and microcharcoal records

Abstract

Loess is an eolian sediment and one of the Earth's most important surficial deposits, recording the evolution of arid climates. The loess in northwest China has received less research attention than that of the Chinese Loess Plateau. In this study, we obtained a 1Ma sporopollen and microcharcoal record from a 207m deep loess core extracted from the West Kunlun Mountains, southern Tarim Basin, representing China's driest inland region. Two ecological-environmental shifts were identified, at about 0.6Ma and 0.1Ma, when the percentage of shrub and herb pollen (especially the percentage of xeromorphic plants) and concentration of microcharcoal increased in stages, indicating increasing aridity and the stepwise expansion of the adjacent Taklimakan Desert. In addition, the percentage of broad-leaved trees decreased during these stages, while the percentage of conifers increased, which might indicate that the climate gradually became colder. Therefore, the long-term cooling may have been the main driving mechanism of stepwise aridification.