[1] 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 d 18 O 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 d 18 O 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.

▪ Abstract  This paper presents a general review of the recent research advances of the East Asian paleomonsoon, based mainly on studies of the loess-soil sequences in the Chinese Loess Plateau. In the last 2.6 million years, the paleomonsoonal history may be divided into about 166 events on a time scale of the Earth's orbital variations. During the last glacial period, millenial-scale oscillations of the monsoon system were prominent, which can be fairly well correlated with the Dansgaard-Oeschger cycles recognized in the Greenland ice cores. The monsoonal rainfall belt has experienced a wide, repeated advance-retreat change during the glacial-interglacial cycles of the Pleistocene. Both temporal and spatial changes of the monsoon system in the Quaternary could have been linked closely to global ice-volume variations.

Particle-size measurements of some typical loess-soil samples taken in different localities of the Chinese Loess Plateau demonstrate that the grain size ratio of <2 μm/>10 μm (%) can be used as an indicator of variations in intensity of the East Asian winter monsoon winds. Grain-size curves of the Baoji and Weinan sections show that this proxy indicator is very sensitive to loess-soil alterations. Analytical results also suggest that during soil-forming periods, eolian dust accumulation was still substantial and, hence, loess deposition can be regarded as a nearly continuous process during the Quaternary period. In this study we compared the Baoji grain-size time series with the SPECMAP marine isotope record with the objective of elucidating the dynamic linkage between changes in global ice volume and the winter monsoon circulation. Both records show good agreement at both time and frequency domains. In particular, the winter monsoon variations are also dominated by a 100,000 yr period over the past 800,000 yr. It is thus inferred that direct local insolation forcing could be less important in driving the East Asian winter monsoon variability, and, alternatively, variations in glacial-age boundary conditions may have played a key role in modulating and pacing its strength and timing.

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