HR: 1330h
AN: PP42A-0864    [PDF]
TI: Abrupt Holocene Climatic Changes: Evidence From The Western Chinese Loess Plateau
AU: An, C
EM: cban@lzu.edu.cn
AF: National Laboratory of Western China­_s Environmental Systems, MOE, Lanzhou University, Lanzhou, 730000 China
AU: * Feng, Z
EM: fengz@mail.montclair.edu
AF: Department of Earth and Environmental Studies, Montclair State University, Upper Montclair, NJ 07043 United States
AB: The abrupt shifts in last glacial climate at high latitudes in the Northern Hemisphere have been well documented. Recent studies show that substantial and possibly global climate oscillations have occurred during the Holocene with pacing similar to the glacial events. However, by comparison, the signal of climate change in Holocene is relatively muted. To address this problem, well-dated and high-resolution paleoclimate data are needed from different geographic locations. We carefully examined two representative Holocene sections in the western part of the Chinese Loess Plateau, which contain high-resolution information regarding the Holocene climatic and environmental changes. A wetland/swamp layer distributes ubiquitously in the western part of the Chinese Loess Plateau. The grayish-blue and carbonate-enriched layer at Sujianwan section, dated between ~10,000 and 4,000 cal. yr. BP, is full of aquatic mollusks and has the highest tree and shrub pollens. A much thicker Haiyuan section, about 10 m thickness, expresses the climatic changes more pronouncedly. Our field-observed and lab-analyzed data show that during the period between ~10,000 and 4,000 cal. yr. BP, a wetland/swamp complex documented six dry/wet cycles, each of which contains multiple sub-cycles. The subsequent period from 4,000 cal. yr. BP to about 2,000 cal. yr. BP (?) was loess deposition period, indicating a dry and windy climatic condition. A soil/loess/wetland complex formed during the past 2,000 years suggests highly variable but generally moister climatic conditions. To sum up, six major cycles of climatic changes characterized the early and middle Holocene from ~10,000 to 4,000 cal. yr. BP. A general dry and windy climatic condition started abruptly about 4,000 cal. yr. BP and ended also abruptly about 2,000 cal. yr. BP. The soil/loess/wetland complex implies that the climate has been quite instable during the past 2,000 years.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1620 Climate dynamics (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting