Holocene climatic change revealed by aeolian deposits from the Gonghe Basin, northeastern Qinghai–Tibetan Plateau

A climate record for the Gonghe Basin in the northeastern Qinghai–Tibetan Plateau during the Holocene period was determined from a 3.90 m aeolian deposit. As revealed by the variation of proxies, including sedimentary facies, magnetic susceptibility, the total organic carbon (TOC) content, grain size, and geochemical parameters, the regional climatic evolution during this period can be divided into the following stages. There was a cold and dry phase in 11.8–10.1 ka, probably related to the Younger Dryas (YD) event prior to the Holocene. An optimum stage with relatively warmer and wetter climate dominated the region between 10.1 ka and 8.7 ka. The climate tended to relatively dry condition from 8.7 ka to 4.7 ka, although weak paleosol (weakly developed paleosol) developed during this period. This is inconsistent with the Megathermal Maximum in the Holocene or Holocene Optimum. A relatively warm and wet climate emerged in 4.7–0.7 ka, and an obviously cold and dry stage emerged since 0.7 ka. Thereafter, the regional climate became warmer. In addition, eight cold events were recorded, including the YD event (around 11.8 ka), 9.8–9.5 ka, 9.2–8.7 ka, 8.1–7.6 ka, 7.0–6.1 ka, 5.3–4.7 ka, 3.1–1.5 ka, and since 0.7 ka. These events are coincident with cold phases revealed by aeolian depositions and lake records in the northeastern Qinghai–Tibetan Plateau, and also with the evidence of deteriorated climate phases in the high and low latitudes of the Northern Hemisphere on a millennial scale, such as in Hongyuan peat and drift-ice tracers in the North Atlantic Ocean in the Holocene.