Holocene millennial-scale climate variations documented by multiple lake-level proxies in sediment cores from Hurleg Lake,Northwest China |
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| Authors: | Cheng Zhao Zicheng Yu Yan Zhao Emi Ito Kenneth P Kodama Fahu Chen |
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| Institution: | (1) Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, PA 18015, USA;(2) Department of Earth Sciences, The University of Hong Kong, James Lee Science Building, Pokfulam Road, Hong Kong, China;(3) MOE Key Laboratory of Western China’s Environmental System, Research School of Arid Environment and Climate Change, Lanzhou University, 730000 Lanzhou, China;(4) Limnological Research Center, Department of Geology and Geophysics, University of Minnesota, 310 Pillsbury Drive SE, Minneapolis, MN 55455, USA |
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| Abstract: | Millennial-scale climate variability has not been well documented in arid northwest China due to the scarcity of high-resolution,
well-dated paleoclimate records. Here we present multi-proxy records from sediment cores taken in freshwater Hurleg Lake on
the northeastern Tibetan Plateau, which reveal millennial-scale lake-level and climate variations over the past 8,000 years.
This high-elevation region is very sensitive to large-scale climate change, thus allowing us to better understand Holocene
climate variations in East Asia. The lake-level record, derived from lithology, magnetic mineralogy, carbonate isotopes, ostracode
shell isotopes and trace elements, X-ray fluorescence (XRF), and gray scale data, indicates a highly variable and generally
dry climate from 7.8 to 1 ka (1 ka = 1,000 cal year BP), and a relatively stable and wet climate after 1 ka. Superimposed
on this general trend, six dry intervals at 7.6–7.2 ka, 6.2–5.9 ka, 5.3–4.9 ka, 4.4–3.8 ka, 2.7–2.4 ka, and 1.7–1.1 ka were
detected from the high-resolution carbonate content and XRF data. The generally dry climate between 7.8 and 1 ka was almost
synchronous with the decrease of East Asian and Indian monsoon intensities shortly after 8 ka. The six dry intervals can be
correlated with weak monsoon events recorded in the East Asia and Indian monsoon regions, as well as the North Atlantic cold
events. Our data suggest that millennial-scale monsoon variations could cause highly variable climate conditions in arid northwest
China during the Holocene. These millennial-scale climate variations may reflect changes in solar variation and/or changes
in oceanic and atmospheric circulation. |
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