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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 discusses the Anisotropy of Magnetic Susceptibility (AMS) records during late Neogene to early Quaternary from the Lantian loess section near the southern margin of the Chinese Loess Plateau. The AMS results for this site are shown to reflect variations in the direction of the paleomonsoon. The Lantian loess sediments are largely aeolian in origin, but also include a thin layer that exhibits secondary aqueous depositional features. The major ellipsoid axis AMS orientations in the loess samples indicate a pervasive Northwest–Southeast directional component since the late Neogene. Since that time, the W–E component gradually overtakes the N–S component, which may explain the trend toward increased aridity during that time. Finally, a local heavy rainfall event seemingly occurred in the Lantian region about 2.6 Ma, which may have been responsible for the aqueous redeposition of sediments observed in L 33 layer in this study. [ABSTRACT FROM AUTHOR]

Abstract: The papers in this special issue are derived from a selection of presentations given at the RACHAD workshop titled “Pattern of Holocene Climate Change in Central Asia: Data Synthesis” held at Lanzhou University, People''s Republic of China, from 25th to 27th July 2006. RACHAD is INQUA Palaeoclimate Commission (PALCOMM) Project (#0502), concerned with ‘rapid climate change in Central Asia''s drylands’, and the 2006 workshop was its fourth gathering. The RACHAD project was established in 2000 and has been led by Prof Fahu Chen from Lanzhou University. RACHAD''s initial objectives were to stimulate the reconstruction of Holocene climatic and environmental changes in arid Central Asia at high resolution, to intensify international research collaboration, and to develop and refine techniques for environmental reconstruction and dating. [Copyright &y& Elsevier]