Late Holocene eolian dust activity recorded by a peat sequence in North Xinjiang, northwestern China

Abstract

Information on the magnitude of dust emissions in source areas is critical for understanding the Asian dust cycles. However, high-resolution records representing the intensity of dust entrainment are scarce, primarily due to intense wind erosion in source areas. Here, based on measurements of multiple proxies from peat deposits, including ash flux, grain size, elemental compositions, and lead and neodymium isotopes, as well as radiocarbon dating of plant remains, we construct a ∼ 3400-year record of eolian dust activity in the Chaiwopu (CWP) Basin, northern Xinjiang, with a maximum temporal resolution of approximately 15 yr per sample. Mineral particles in the CWP peat were primarily transported by wind through either saltation or suspension across different sedimentary intervals. Geochemical proxies indicate that the primary source of these mineral particles is the Junggar Basin, which allows the peat to consistently record information on the interactions between wind regimes and the entrainment of sand and dust during the late Holocene. In light of changes in the >63 μm fraction and ash flux, episodes of eolian dust activity occurred at 3.3–2.8, 1.7–1.4, 1.0–0.5 cal kyr BP and since 0.2 cal kyr BP. These events are largely comparable to dust episodes recorded in other studies, particularly the Neor peat sequence from northwestern Iran. By contrast, the most intense eolian activity at 3.3–2.8 cal kyr BP was dominated by dust storms, which can be attributed to a broad cold and dry climate, likely linked to Ice-Rafting Event 2 in the North Atlantic, as well as to an increased sediment supply due to climatic transitions. Subsequently, eolian activities weakened, characterized by the mobility of silt-sized dust under windy and slightly dry conditions. However, the event since 0.2 cal kyr BP was likely triggered by disturbances to the source surface due to increased human activity. Our results suggest a potential link between the source and sink of dust, such as the GISP2 ice cores. In addition to large-scale cold and dry climates, intensified dust emissions from source areas would play a significant role in establishing this dynamic linkage of airborne dust.