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Journal of Desert Research ›› 2018, Vol. 38 ›› Issue (5): 963-971.DOI: 10.7522/j.issn.1000-694X.2017.00065

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Rare Earth Elements' Geochemical Characteristics of Nebkhas in the Qaidam Basin and the Provenance

Ling Zhiyong1,2, Wang Jianping2, Chen Liang2, Lu Baoliang2   

  1. 1. Key Laboratory of West China's Environmental System, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China;
    2. Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China
  • Received:2017-05-09 Revised:2017-07-11 Online:2018-09-20 Published:2018-11-03

Abstract: Rare Earth Elements (REE) are widely used as trace elements in provenance studies of various sediments, and their characteristics also can record the evolution of environment more detailly. Therefore, they are widely used as an important indicator in studies of paleoclimate changes. The relationships between REE characteristics and environmental change on aeolian deposits have intensively been investigated in the Chinese Loess Plateau. However, the relationships between REE and paleoenvironment recorded by aeolian sediments of nebkhas in the Qaidam basin are still poorly understood. So the REE characteristics and environmental implication revealed by aeolian sedimental profiles of nebkhas in the Qaidam basin were studied. The results show that REE values of nebkhas' profiles vary from 100.527 μg·g-1 to 163.47 μg·g-1, and they are close to the REE values of Xinjiang Sierozem, but slightly lower than the Chinese loess. The LREE values determined the changes of the total content of REE with a range of 87.80~144.65 μg·g-1, which percentage changes from 86.62% to 90.53%. Overall, the LREE is relative enrichment and relatively low HREE abundance, with similar fractionated characteristics of REE. The distribution patterns of REE are the slowly gradient "L" types, and distribution patterns of Eu elements are moderate negative anomaly, and Ce elements show no obvious abnormality and more reflect their source features. The source of nebkhas sediments is mainly composed of detrital deposits material which come from the alluvial fans located in northern slope of East Kunlun, not from the lakes bottom erosion in the drought periods. After weathering, transportation and deposition, the clastic sediments become the aeolian sediments of nebkhas in southern of the Qaidam basin. The differentiation characteristics of rare earth elements primely record the regional climate and environmental changes by the development of nebkhas in the Qaidam basin. On the whole, the characteristics of REEs revealed dry climate condition in the whole development of nebkhas in the Qaidam basin, with weak chemical weathering, relatively poor vegetation growth condition, and the pedogenesis effect is not obvious.

Key words: nebkhas, rare earth elements(REEs), geochemical characteristics, sediment provenance, Qaidam Basin

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