• 责任者：Bai Youliang (School of Geology and Minerals Resources ; Lanzhou University ; Lanzhou 730000 ; China) ; Jiang Hanchao
• 刊名：Quaternary Sciences
• 出版年：2013
• 卷期：33(5)
• 关键词：中更新世 ; Middle Pleistocene ; 湖泊沉积物 ; lake sediments ; 孢粉组合 ; palynological assemblage ; 新疆 ; Xinjiang
• 页码：p.856-865
• 图表：5 illus., 52 refs.
• 分类号：1400
• issnNo：ISSN1001-7410
• isbnNo：CN11-2708/P

     In this study,a 4.5-m-thick section of lake sediments（89°53＇N,40°41＇E）was discovered in the northern margin of the Peacock River in Northwestern China.It is located at Xidagou,Tarim town,Yuli county,eastern Xinjiang Province.From up to bottom,four Electron Spin Resonance（ESR）ages were achieved,435±43kaB.P.at 1.0m,473±47kaB.P.at 1.5m,636±63kaB.P.at 3.2m,and 691±69kaB.P.at 4.2m.These suggest that this section spans a mid-Pleistocene interval of 730-360kaB.P.and establishes a reliable chronological framework for the Xidagou section.In the meanwhile,18 pollen samples were analyzed and 5107 grains of pollen and spores were identified（mean 284 grains/sample）.A total of 66 spore and pollen types were identified.On the whole,arboreal pollen taxa were dominant in most of the samples,ranging from 54.1% to 65.8% in abundance with an average of 58.6% .Shrubs and herbs were less dominant,fluctuating between 20.2% to 30.3% in abundance and averaging to 23.2% .Fern spores and algae ranged from 11.9% to 22.6% in content and had a mean of 17.2% .These indicate that,during the deposition of this section,the study area was generally covered continuously by broadleaved forests,under which various shrubs and herbs grew vigorously.Ferns and algae mainly distributed in some low-lying humid places within the study area.Main taxa included Castanea,Quercus,Pinus,Cupressaceae,Artemisia,Chenopodiaceae,Cyperaceae,etc.Also present were Carya,Liquidambar and Pterocarya,and these subtropical types occurred commonly with low and erratic percentages.The presence of these taxa and their content variations were well consistent with development of a big lake in the study region during the mid-Pleistocene inferred from previous studies.Specifically,in zones A（730-640kaB.P.）,C（595-505kaB.P.）and E（440-385kaB.P.）,the broadleaved arboreal pollen was always high in abundance while the shrub and herb pollen was usually low.In zones B（640-595kaB.P.）,D（505-440kaB.P.）and F（385-350kaB.P.）,the broadleaved tree pollen was generally low and the shrub and herb pollen was high on the whole.These suggest that climate in the study area varied generally between dry-cold and humid-warm patterns during the mid-Pleistocene period.This mode of climate change in the study area is well correlated with the changes of weathering intensity revealed by the multi-proxies of the Baishui section,in Gansu Province,such as SiO2 content,LOI,CIA and Md.Furthermore,they could be correlated with the integrated benthic δ18O record and the document of global sea level.Nevertheless,the internal forcing mechanism for this mode of climate changes in the study area remains unclear up to now and deserves further investigation.