Chinese loess record of monsoon climate during the last glacial-interglacial cycle

The thick loess-paleosol succession of central China contains a detailed re cord of changes in East Asian monsoon climate since the late Miocene Epoch. The alternating loess-paleosol stratigraphy closely resembles the marine o xygen-isotope record. implying that episodic dust deposition and pedogenesi s are in phase with global ice-volume fluctuations and controlled by variat ions in solar radiation reaching the land surface. Deposits equivalent to m arine isotope stages (MIS) 5 through 1 have been dated by C-14, Be-10, lumi nescence, and magnetic susceptibility and grain-size models. Malan Loess (M IS 4-2) decreases in thickness southeastward from > 30 In in the western Lo ess Plateau to < 5 In east of Xi'an. Downwind, Asian dust is found in Japan , the North Pacific Ocean, and the Greenland Ice Sheet, where it has a chem ical signature that points to a primary source in western China. During gla cial times, the mean dust flux in the central Loess Plateau reached 0.35 mm /year, whereas in interglacial times it fell to < 0.1 mm/year. Times of hig h dust influx and reduced soil development coincided with strengthened wint er monsoon conditions, which are inferred from variations in loess grain si ze. Times of decreased dust accumulation and strong pedogenesis, marked by high values of magnetic susceptibility, represent times of strengthened sum mer monsoon conditions. High-frequency fluctuations in dust influx during d eposition of the Malan Loess include peaks that likely correlate with North Atlantic Heinrich events. The Younger Dryas oscillation is recorded in Chi nese eolian and organic deposits by a shift from cool, humid late-glacial c onditions to cold and dry conditions, followed by a return to milder. humid climate at the beginning of the Holocene. Warm, moist climate, associated with a strong summer monsoon, characterized the first half of the Holocene Epoch when a widespread paleosol complex developed on the Loess Plateau. In creased dust deposition during the middle to late Holocene marked a shift t o cooler, drier conditions. (C) 2001 Elsevier Science B.V. All rights reser ved.