Unparallel MIS13 climate evolution between western and eastern Chinese Loess Plateau

The quasi-continuously deposited Chinese loess is widely recognized as one of the most important paleoclimatic and paleoenvironmental archive for Quaternary climate. The paleosol layer S5S1, corresponding to the Marine Isotope Stage (MIS) 13, is the most prominent paleosol layer in the central Chinese Loess Plateau (CLP). According to the pedogenesis evidence there, previous studies suggested that the North Hemisphere was then dominated by humid and warm climate under the strong East Asian Summer Monsoon (EASM). It seems contradicted with the common understanding that the period was prevailed by large global ice volumes in the past interglacials. Recently, it is found that in some of the CLP loess sequences, the phenomenon is lacking. Then a question is raised if the EASM is really strong at that time. In this study, we made a thorough review of previous studies, and discovered that the strongly pedogenic S5S1 units are located in the East and Central CLP only, while the pedogenesis was weak in the West CLP. Comparing the Africa-Asian monsoon records with those in the region of mid- and high latitudes in the North Hemisphere, it is found that the abnormal MIS13 climate occurred only in the Africa-Asian monsoon region, but not the high latitude region of the North Hemisphere. In addition, the abnormal climate on CLP is possibly characterized by humidity, but not temperature. Based on the facts mentioned above, it is proposed that the EASM did not cover the region of West CLP during MIS13 benefited from the atmosphere dynamics, which caused the unparallel pedogenesis of loess-paleosol sequences between the West and East CLP.