Grain-size characteristics and climate variability in TMS5e sequence of Tumen section in southern Tengger Desert, northwestern China |
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Authors: | Xiaohao Wen Baosheng Li Fengnian Wang Yanming Zheng Dongfeng Niu Yuejin Si Xianjiao Ou |
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Institution: | School of Geographical Science,South China Normal University,Guangzhou 510631,China;2.State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi’an 710075,China;3.School of Geography and Planning,Sun Yat-Sen University,Guangzhou 510275,China;4.School of Geography and Tourism,Jiaying University,Meizhou 514015,China) |
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Abstract: | The TMS5e sequence from the Tumen section, at the southern edge of Tengger Desert in the northwestern China, is synchronous
with Marine Isotope Stage 5e (MIS5e). It consists of 16 layers of aeolian dune sands, 11 layers of lacustrine loess-like facies,
and 5 layers of lacustrine facies. The results of grain-size analysis shows that the palaeo-mobile dune sands, palaeo-fixed
to semi-fixed dune sands and loess-like sandy loams are mainly composed of sands, ranging from 70% to 96%; their silt contents
ranged from 4% to 20%, and their clay contents ranged from 1% to 5%; the climate under which the aeolian dune sands were deposited
is similar to that under which modern mobile dune sands form, which is caused by the dominance of the cold, dry East Asian
winter monsoon. In contrast, the lacustrine loess-like facies and lacustrine facies had a lower sand contents than those of
the three aeolian dune sands, but have higher silt and clay contents, most of their sand content ranged from 30% to 60%, their
silt contents ranged from 35% to 55%, and their clay contents ranged from 6% to 20%. The lacustrine loess-like facies and
lacustrine facies formed under the influence of the warm, humid East Asian summer monsoon based on their similarity with modern
sediments. The grain-size indicator Mz (mean grain diameter) and the SC/D value in the TMS5e sequence indicate climatic instability
at the southern edge of the Tengger Desert during MIS5e, with at least 14 fluctuations between a warm, humid climate and a
cold, dry climate, divided into five stages: TMS5e5 (139 kyr to 129.3 kyr B.P.), TMS5e4 (129.3 kyr to 124 kyr B.P.), TMS5e3
(124 kyr to 119.5 kyr B.P.), TMS5e2 (119.5 kyr to 116.5 kyr B.P.), and TMS5e1 (116.5 kyr to 113.7 kyr B.P.). These correspond
roughly to MIS5e5, MIS5e4, MIS5e3, MIS5e2, and MIS5e1, respectively, in the GRIP ice core data. |
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Keywords: | Tengger Desert Tumen section TMS5e sequence grain-size characteristics palaeoclimate reconstruction Marine Isotope Stage 5e(MIS5e) |
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