Stacked 2.6‐Ma grain size record from the Chinese loess based on five sections and correlation with the deep‐sea δ18O record

Abstract

This study aims to establish a stacked climate record of the Quaternary period from the Chinese loess sequence and to address the forcing mechanisms for the regional climate history of the Loess Plateau by correlating the stacked record with a composite δ18O record in deep‐sea sediments. A total of 18,352 samples were obtained from five loess sections, located at Baoji, Lingtai, Jingchuan, Puxian, and Pingliang in the southern and middle Loess Plateau. These yielded high‐resolution grain size records. Between‐section correlation of these shows that although small depositional hiatuses are present in places within a single section, most parts of the sections display near‐continuous dust deposition throughout the Quaternary. The grain size records were tuned simultaneously to the theoretical variations in obliquity and precession of the Earth’s orbit. The grain size records plotted on their orbital timescales were then averaged to form a stacked loess grain size time series, termed the “Chiloparts” record. This resolves most of the orbital timescale paleoclimate events buried in the loess‐soil sequences of the southern and middle Loess Plateau and can be used as a regional archive of the Pleistocene climate history in the Loess Plateau. Comparison of the “Chiloparts” record with a composite marine δ18O record shows that for the past 1.8 Ma, the loess‐paleosol record can be correlated almost cycle by cycle with the marine record. Several discrepancies in the climatic events between the two records have also been identified, implying that regional forcing mechanisms may have played a part in the climatic evolution of the Chinese Loess Plateau.