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The variability and dynamics of the Asian monsoon (AM, hereafter indicates both of the summer and winter monsoons.) at orbital and millennial timescales has attracted wide interest. Chinese loess deposits, covering an area of ~500 × 103 km2 and with a thickness of several tens to more than three hundred meters, is an ideal continental archive to reconstruct AM variations during the Quaternary epoch. Over the past thirty years, since the earliest paper published in an international journal that linked the Asian monsoon and Chinese loess deposits, many studies have been undertaken focusing on this research topic. These results have greatly deepened our understanding of the variations of the AM climate and their driving mechanisms during the past ~2.6 Myr. In this paper, we emphasize recent progress on the AM variability and dynamics revealed by Chinese loess records; in particular, we discuss the reliability and precision of the timescale and the monsoon proxy indicators for the loess-paleosol sequences, which are two fundamental aspects for understanding AM behavior. We analyze what we know and discuss what we do not know about the AM. We refine the timescale for the typical loess-paleosol sequence in the central Chinese Loess Plateau (CLP), which can be used as a new timescale to study palaeoclimate and palaeoenvironmental changes in the monsoonal Asia. We conclude that low-latitude insolation changes induced by precession, and global ice volume, temperature at high-latitudes, as well as sea-level changes forced variations of the AM at orbital time scales. High-latitude cooling events and low-latitude hydroclimate process at millennial time scales, such as climate changes associated with Heinrich events and Dansgaard-Oeschger cycles in Northern Atlantic and Greenland, have also modulated AM variability. We suggest that high-latitude forcing of AM variations occurs through ocean and atmospheric circulation linkages, although the roles of atmospheric CO 2 , ocean and vegetation feedbacks need further investigation. In future study, high-resolution independent dating, novel proxy indices and transient numerical simulations are still basic tools to understand the loess deposition and AM variations that require considerably more work. Issues such as reliable spatial comparison and regional linkages of records (dependent on precise and accurate numerical chronologies), and quantitative reconstruction of the AM variations, should be given priority in the study the past climate change in Asia, and low-latitude hydroclimate process. [ABSTRACT FROM AUTHOR]

This paper proposes a new method to distinguish between interglacial deposits and pedogenically-overprinted glacial loess based on the concentration variations of coarse-grained aeolian (magnetically pseudo-single domain and multidomain) magnetite. We apply the method to a sequence from the upper part of the loess unit L2 (marine isotope stage MIS 6) to the sub-loess unit S1L2 (MIS 5d) at the YuanBo (YB) section in the Chinese Loess Plateau. The method is based on the differences in low temperature properties between the coarse-grained (multidomain and pseudo-single domain) detrital magnetite and the pedogenic magnetic particles including superparamagnetic (SP) particles and relatively larger (>SP) maghemite particles. The former is characterized by a crystallographic Verwey transition around 120 K. In contrast, the magnetization of the latter continuously decreases in intensity with increasing temperatures. The method involves two steps: (1) calculating the first-derivative of the low temperature thermal demagnetization of the saturated isothermal remanent magnetization acquired at 20 K (LT-SIRM), which enhances the behaviour related to the Verwey transition, and (2) fitting a third-order polynomial background to the data between both 50–70 and 150–300 K, and then subtracting this background from the total derivative curves. The area under the background-corrected derivative curves represents the absolute intensity drop associated with the Verwey transition (Δ JTV ). This is caused by the aeolian coarse-grained magnetite, which is very sensitive to the changes in the intensity of the winter monsoon, and in turn related to the changes in palaeoclimate. The results show that the sharp drop of Δ JTV at 39.44 m corresponds to the climatic boundary from L2 (MIS 6) to S1S3 (MIS 5e), and not at 39.8 m as thought previously. Thus, the palaeosol deposits just below this boundary are in fact highly altered L2 materials instead of S1S3 accumulations. [ABSTRACT FROM AUTHOR]