Loess record of climatic changes during MIS 12–10 in the Jingyuan section, northwestern Chinese Loess Plateau

Abstract

Marine Isotope Stage 11 (MIS 11) has been considered as a potential analog for the present interglacial, based on orbital scale solar insolation variations. Therefore, increasing attention has been paid to MIS 11 and the contiguous stages in recent studies of marine and terrestrial records, as they may provide clues for predictions of future climate change. In the Chinese loess-palaeosol sequences, S4 soil, interpreted as corresponding to MIS 11, yields a precise terrestrial palaeoclimate record for this period. In this study, a loess-palaeosol sequence (L4–L5) from the Jingyuan Section on the northwestern margin of the Chinese Loess Plateau (CLP) was investigated to reconstruct the climatic variability during the periods MIS 12–10, using proxies of grain size, magnetic susceptibility, total organic carbon and soil color index. The results suggest that the L4–L5 sequence in the Jingyuan Section is much thicker (∼40 m) than those in the central Loess Plateau areas (∼12 m). The L5 loess, equivalent to MIS 12, developed under relatively cold and dry conditions. Climate evolution during this period was not as severe as that indicated in the marine isotopic records. An episode of warmer and more humid conditions occurred during the middle stages of MIS 12, reflecting a strengthened summer monsoon during the glacial period. A similar scenario has been observed in the middle part of MIS 10. High-resolution multi-proxy records for MIS 11 suggest that a general warm–humid climate was dominant during the formation of S4 soil. However, at least four fluctuations occurred, reflecting unstable climate conditions and regional climate differences within the northwestern margin of the CLP during this period. The study also shows that the early part of S4, spanning over 30 ky, was very warm and humid, while the later part was characterized by mild-cool conditions.