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Geoscience ›› 2021, Vol. 35 ›› Issue (05): 1311-1322.DOI: 10.19657/j.geoscience.1000-8527.2021.077

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MIS6-MIS5 Climate Change of Yinchuan Basin Based on End-member Method

XU Keke1,2(), YANG Zhenjing1(), NING Kai1, HAN Qiangqiang3, BI Zhiwei1, ZHAO Nannan4   

  1. 1. Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Zhengding, Hebei 050800, China
    2. China University of Geosciences, Beijing 100083, China
    3. Institute of Hydroenvironmental Geology Exploration, Geological Bureau of Ningxia Hui Autonomous Region,Yinchuan, Ningxia 750011, China
    4. Center of Land and Resources Exploration, Hebei Bureau of Geology and Mineral Resources Exploration, Shijiazhuang, Hebei 050000, China
  • Received:2021-04-20 Revised:2021-06-03 Online:2021-10-10 Published:2021-11-04
  • Contact: YANG Zhenjing

Abstract:

The Yinchuan Basin is located in the junction of the East Asian monsoon and the west wind strip. Sediments in the basin records the climatic environment evolution. In this study, the climatic evolution sequence (MIS6-MIS5 period) in the basin was reconstructed with photoluminescence dating, grain-size analysis, and end-element analysis on sediments from borehole LS01. Four end-members (Em1 to Em4) with specific environmental indications were obtained from the end-element analysis. Em1: weak flow or lacustrine-facies deposits with weak hydrodynamics; Em2: fluvial deposits with strong hydrodynamics; Em3 and Em4: regional tectonic uplift. The climate evolution comprises six stages (1-6): (1) Yinchuan Basin had cold-arid climate with two tectonic uplift events in 150-137 ka (MIS6); (2) The climate was warm and humid as a whole, and there were three warm events at a1 (137-129 ka), a2 (124-120 ka), and a3 (118-111 ka) in 137-110 ka (MIS5); (3) the climate turned to cold and arid in 110-107 ka (MIS5); (4) 107-102 ka (MIS5), cold events b1 (106-104 ka) and b1 (106-104 ka) occurred and the climate was cold and dry in general; (5) 102-87 ka (MIS5), the climate was cold and arid; (6) in 84-75 ka (MIS5), there was a cold event L2 (87-84 ka) but the climate was warm and humid as a whole. The climate change in MIS6-MIS5 phase was mainly driven by solar radiation and precession in summer.

Key words: sediment grain size, end-member analysis, grain size-standard deviation, Yinchuan Basin, climate change

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