HR: 15:45h
AN: PP33D-08    [Abstracts]
TI: Holocence Climatic Changes in the Mongolian Plateau
AU: * Feng, Z
EM: zhaodong_feng@baylor.edu
AF: Deparment of Geology, Baylor University, One Bear Place #97354, Waco, Tx 76798, United States
AU: * Feng, Z
EM: zhaodong_feng@baylor.edu
AF: Department of Geography, Lanzhou University, 222 Tianshui Nanlu, Lanzhou, Gan 730000, China
AU: Zhai, X
EM: Zhaixw926@lzu.edu.cn
AF: Department of Geography, Lanzhou University, 222 Tianshui Nanlu, Lanzhou, Gan 730000, China
AU: Wang, W
EM: weiw03@lzu.cn
AF: Department of Geography, Lanzhou University, 222 Tianshui Nanlu, Lanzhou, Gan 730000, China
AU: Ma, Y
EM: Mayzh@lzu.edu.cn
AF: College of Resource Sciences, Beijing Normal University, 19 Xinjiekuo Waidajie, Beijing, BJ 100875, China
AU: Guo, L
EM: llguo@ires.cn
AF: College of Resource Sciences, Beijing Normal University, 19 Xinjiekuo Waidajie, Beijing, BJ 100875, China
AB: This study compares lacustrine and nearby eolian sections at sites in the Southern and Northern Mongolian Plateaus in order to test spatial climate variability during the Holocene. Based on the lithology, proxy data, and 14C dated and the interpolated ages, following observations can be made. In the northern Mongolian Plateau best developed Holocene paleosol (Mollisol) dated at ~8,600-~7000 14C yr BP at the Shaamar section and the carbonate-rich laminated layer in the Gun Nuur lake core mark the interval of warmer and dryer climate (i.e., grassland domination) during the early Holocene (~8,300-~7400 14C yr BP). Younger paleosols at the Shaamar section and corresponding organic-rich layers in the Gun Nuur core were formed under distinctly cooler and more humid conditions. Minor soils (Entisols) and associated pollen assemblages indicate that the climate in the Northern Mongolian Plateau ameliorated four times during mid-late Holocene: (1) around 4800 14C yr BP, (2) around 3800 14C yr BP, and (3) around 3000 14C yr BP, and (4) during the past 1600 14C yr BP. The Baahar Nuur lake core in the Southern Mongolian Plateau and the Dingxi eolian section in the western part of the Western Chinese Loess Plateau appear to be supportive of the notion that prolonged interval of maximum humidity prevailed in this region during the early- and mid-Holocene (9,000-4,000 14C yr BP). The late Holocene at the Dingxi section consists of three paleosol-loess couplets and the three weakly developed paleosols (i.e., Entisols) were inferred to have been formed from ~3500 to ~3100 14C yr BP, from ~2900 to ~2400 14C yr BP, and from ~2000 to ~1000 14C yr BP, respectively. The lake-core proxy data indicate that the Holocene Climatic Optimum (equivalent to the highest productivity) in the Northern Mongolian Plateau occurred from ~6000 to ~1500 14C yr BP and the Climatic Optimum occurred in the Southern Mongolian Plateau and in the western part of the Chinese Plateau from ~9000 to ~4000 14C yr BP. This discrepancy implies that the concept of the Holocene Climatic Optimum has limitations and may have to be reconsidered if it is intended to have a large-scale connotation. We also notived that the climate appeared to have changed in cycles of ~1500 years in the North (comparable with those in North Atlantic) and tt appeared to have changed in cycles of ~1000 years in the South (comparable with those in the Santa Barbara basin--- needs to be further confirmed).
DE: 1600 GLOBAL CHANGE
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting