Holocene Moisture Variability and Its Lagged Response to Summer Insolation Revealed by Eolian Deposits in the Lake Qinghai Basin, NE Tibetan Plateau

Abstract

AbstractThe evolution of the East Asian Summer Monsoon (EASM) and its mechanism since the Holocene remains controversial. Here, we investigate four eolian sediment sequences in the Lake Qinghai Basin (LQB), Northeastern Tibetan Plateau (NETP), in the marginal zone of the modern EASM. The results indicate that paleoclimatological interpretation of the color parameters and CaCO3 in eolian sand‐paleosol sequence from LQB region are different from the loess‐paleosol sequence in Loess Plateau, and a comprehensive analysis that combines lithostratigraphic and other proxy data is required. Changes in the EASM dominated climate change in the NETP, with a gradual increase in moisture from the beginning of the early‐Holocene, however the environment was relatively cold and dry with strong regional eolian sand activity. During 8.5–3.3 ka, the intensity of the EASM and effective moisture levels in the LQB reached a peak. Eolian activity was weak and dunes were effectively fixed in place, while pedogenesis processes were enhanced and paleosols developed widely across the region. Moisture levels decreased after 3.3 ka and the dunes were reactivated, eolian activity was enhanced, and there was extensive accumulation of eolian sand and sandy loess. These records show that moisture variability has been controlled by the EASM system in east Asia since at least the Holocene, and has generally responded to changes in northern hemisphere summer insolation with a lag of 3–5 ka, through mechanisms that are modulated by high‐latitude ice‐volume forcing and large‐scale ocean‐atmospheric circulation patterns.