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Journal of Desert Research ›› 2020, Vol. 40 ›› Issue (1): 64-76.DOI: 10.7522/j.issn.1000-694X.2019.00046

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Grain-size and geochemical compositions of the Harbin loess deposits and their implications for eolian dust provenances

Du Huirong1, Xie Yuanyun1,2, Kang Chunguo2, Chi Yunping1,2, Wang Jiaxin1, Sun Lei1   

  1. 1. College of Geographic Science Harbin Normal University, Harbin 150025, China;
    2. Heilongjiang Province Key Laboratory of Geographical Environment Monitoring and Spatial Information Service in Cold Regions, Harbin Normal University, Harbin 150025, China;
    3. School of Geography and Tourism, Harbin University, Harbin 150086, China
  • Received:2019-02-15 Revised:2019-04-15 Online:2020-01-20 Published:2020-01-18

Abstract: The Harbin loess deposits are located at the easternmost edge of the Eurasian loess belt. The study of eolian dust material origin for the Harbin loess deposits is the key to better understanding the relationship between dust accumulation and regional structure, landform and climate change. However, the investigations for the geochemical composition of Harbin loess deposits have not yet been carried out. Therefore, the grain-size and geochemical compositions of L1 loess in the Harbin Tianhengshan section were analyzed, and chemical weathering, maturity and material sources for the Harbin loess were discussed. In order to trace the material source of the Harbin loess, surface sample collection and geochemical analysis were also carried out in the Northeast Sandy Land (including Hunshandake Sandy Land, Horqin Sandy Land, Hulun buir Sandy Land and Songnen Sandy Land). The results show that the Harbin loess does not contain fine sand components (125-250 μm), but contains moderate amount of extremely fine sand components (63-125 μm, 4.8%-10.5%). The silt (4-63 μm) and clay (<4 μm) components dominantly account for 73%-82% and 12%-18%, respectively. The particle-size pattern was trimodal with modes 36-40 μm, 8-10 μm and 0.8 μm, consistent with the grain size distribution pattern of typical loess in the Loess Plateau, but coarser than that of the loess in the middle Loess Plateau obviously. We showed CIA and W indices, A-CN-K and WMF triangle diagrams, SiO2/Al2O3 ratios and ICV values, and finally a binary diagram of K2O/Al2O3 and Na2O/Al2O3. They revealed that the Harbin Loess has undergone a simple chemical weathering process with a low maturity and recycling history. Combined with grain size, element geochemistry, Sr-Nd isotopic ratios and mathematical statistical methods of MDS and PCA, It is believed that the Harbin loess deposits are from proximal areas, and the Songnen Sandy Land provides the main dust material for the Harbin loess deposits, and that the Hunshandake Sand Land and the Horqin Sand Land may also provide a small amount of fine dust for the Harbin loess deposits and however, the Hulunbuir Sand Land cannot be the source of the Harbin loess deposits. The Harbin loess deposits were the product of dust storm weather in spring.

Key words: provenance, Harbin loess, geochemistry, grain size, Songnen Sandy Land

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