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Climate of the Past An interactive open-access journal of the European Geosciences Union
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Volume 14, issue 3 | Copyright
Clim. Past, 14, 271-286, 2018
https://doi.org/10.5194/cp-14-271-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 06 Mar 2018

Research article | 06 Mar 2018

Eolian dust dispersal patterns since the last glacial period in eastern Central Asia: insights from a loess-paleosol sequence in the Ili Basin

Yue Li1,2,3, Yougui Song1, Kathryn E. Fitzsimmons2, Hong Chang1, Rustam Orozbaev4,5, and Xinxin Li1 Yue Li et al.
  • 1State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
  • 2Research Group for Terrestrial Palaeoclimates, Max Planck Institute for Chemistry, Mainz, 55128, Germany
  • 3College of Earth Science, University of Chinese Academy of Sciences, Beijing, 100049, China
  • 4Institute of Geology, National Academy of Sciences of Kyrgyz Republic, Bishkek, 720040, Kyrgyzstan
  • 5Research Center for Ecology and Environment of Central Asia, Chinese Academy of Sciences, Ürümqi, 830011, China

Abstract. The extensive loess deposits of the Eurasian mid-latitudes provide important terrestrial archives of Quaternary climatic change. As yet, however, loess records in Central Asia are poorly understood. Here we investigate the grain size and magnetic characteristics of loess from the Nilka (NLK) section in the Ili Basin of eastern Central Asia. Weak pedogenesis suggested by frequency-dependent magnetic susceptibility (χfd%) and magnetic susceptibility (MS) peaks in primary loess suggest that MS is more strongly influenced by allogenetic magnetic minerals than pedogenesis, and may therefore be used to indicate wind strength. This is supported by the close correlation between variations in MS and proportions of the sand-sized fraction. To further explore the temporal variability in dust transport patterns, we identified three grain size end-members (EM1, mode size 47.5µm; EM2, 33.6µm; EM3, 18.9µm) which represent distinct aerodynamic environments. EM1 and EM2 are inferred to represent grain size fractions transported from proximal sources in short-term, near-surface suspension during dust outbreaks. EM3 appears to represent a continuous background dust fraction under non-dust storm conditions. Of the three end-members, EM1 is most likely the most sensitive recorder of wind strength. We compare our EM1 proportions with mean grain size from the Jingyuan section in the Chinese loess plateau, and assess these in the context of modern and Holocene climate data. Our research suggests that the Siberian High pressure system is the dominant influence on wind dynamics, resulting in loess deposition in the eastern Ili Basin. Six millennial-scale cooling (Heinrich) events can be identified in the NLK loess records. Our grain size data support the hypothesis that the Siberian High acts as teleconnection between the climatic systems of the North Atlantic and East Asia in the high northern latitudes, but not for the mid-latitude westerlies.

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This paper finds a close tie between loess magnetic susceptibility and wind strength in the Ili Basin, eastern Central Asia, and identifies three distinct aerodynamic environments with end-member modeling analysis of grain size. The Siberian High is the dominant influence on wind dynamics, resulting in loess deposition, and acts as a teleconnection between the climatic systems of the North Atlantic and East Asia in the high northern latitudes, but not for the mid-latitude westerlies.
This paper finds a close tie between loess magnetic susceptibility and wind strength in the Ili...
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