History of moisture change derived from slope sediments of the eastern Gonghe Basin (northeastern Qinghai–Tibetan Plateau) during the last 17 ka

Abstract

AbstractThe palaeosol–loess–aeolian sand sequence in the eastern Gonghe Basin, which is located at the convergence of the Asian summer monsoon, winter monsoon and the westerlies, reveals detailed moisture changes in the northeastern Qinghai–Tibetan Plateau (NETP) during the last 17 ka. Analysis of magnetic susceptibility (MS), total organic carbon, carbonate content, grain size and geochemical parameters indicate that the region was dominated by an extremely dry climate during ~17.0–15.82 ka, accompanying large‐scale desert expansion in the last glacial maximum (LGM). Subsequently, the climate became generally dry during 15.82–14.6 ka, an interval in which loess rapidly accumulated. Enhanced humidity occurred at 14.6 ka, probably associated with increased strength of the East Asian summer monsoon. The region experienced slightly decreased moisture at around 6.5 and 5.8 ka. After 2.7 ka, the climate became wetter. This interpretation correlates with climatic records from lacustrine and aeolian deposits in the NETP during the LGM, the last deglaciation and the early–middle Holocene. High climatic moisture in the Late Holocene facilitated the formation of a well‐developed palaeosol in the NETP. The effective moisture change in the Gonghe Basin is not simply ascribed to the influences of Asian summer monsoons; instead, it was possibly influenced by the interaction of evaporation and monsoonal precipitation forced by solar insolation variation. The balance between these variables was very influential on the effective moisture change in the closed inland basin of the NETP. Copyright © 2016 John Wiley & Sons, Ltd.