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冰川冻土 ›› 2019, Vol. 41 ›› Issue (3): 563-573.doi: 10.7522/j.issn.1000-0240.2019.0305

• 冰冻圈与全球变化 • 上一篇    下一篇

风成沉积地层化学元素记录的毛乌素沙地气候变化

李想1, 苏志珠2, 韩瑞1, 柳苗苗1, 梁爱民3,4, 张彩霞3   

  1. 1. 山西大学 环境与资源学院, 山西 太原 030006;
    2. 山西大学 历史文化学院, 山西 太原 030006;
    3. 中国科学院 西北生态环境资源研究院 沙漠与沙漠化重点实验室, 甘肃 兰州 730000;
    4. 中国科学院大学, 北京 100049
  • 收稿日期:2018-08-07 修回日期:2018-11-17 出版日期:2019-06-25 发布日期:2019-09-10
  • 通讯作者: 苏志珠,E-mail:suzhizhu@163.com. E-mail:suzhizhu@163.com
  • 作者简介:李想(1994-),女,山西孝义人,2013年在太原师范学院获学士学位,现为山西大学环境与资源学院硕士研究生,从事干旱区地貌与环境演化研究.E-mail:mzlx1994@163.com
  • 基金资助:
    国家自然科学基金重点项目(41330748);国家重点研发计划项目子课题项目(2016YFC0500805)资助

Climate change of Mu Us Desert revealed by geochemical elements in the aeolian sedimentary stratum

LI Xiang1, SU Zhizhu2, HAN Rui1, LIU Miaomiao1, LIANG Aimin3,4, ZHANG Caixia3   

  1. 1. College of Environment and Resources, Shanxi University, Taiyuan 030006, China;
    2. Historical Culture School, Shanxi University, Taiyuan 030006, China;
    3. Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China;
    4. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2018-08-07 Revised:2018-11-17 Online:2019-06-25 Published:2019-09-10

摘要: 毛乌素沙地位于东亚季风边缘区,是研究全球气候变化和沙漠变迁的理想场所。选取沙地东缘风成砂/古土壤/湖沼相沉积序列,以常量化学元素含量及比值变化揭示了全新世的气候变化。结果表明:常量化学元素氧化物含量在全剖面上呈SiO2 > Al2O3 > K2O > Na2O > Fe2O3 > MgO > CaO,且在不同沉积相中含量存在差异;常量化学元素氧化物与<63 μm粉黏组分及磁化率的相关性分析显示,Al2O3、Fe2O3、MgO三者之间呈显著正相关性,且与粉黏组分、低频磁化率(Xlf)也呈显著正相关性,表明<63 μm粉黏组分、Xlf可以反映夏季风的强弱;全新世气候变化存在多次暖湿冷干波动,10.39 ka BP之前出现3次快速的气候颤动,表现为3层风成砂与3层湖沼相互层沉积,指示存在3次冬夏季风交替变化;10.39~9.34 ka BP、8.68~8.29 ka BP、2.72~1.34 ka BP为3次明显的冬季风势力增强、风沙活动加剧的相对冷干气候;在9.34~8.68 ka BP、8.29~2.72 ka BP、1.34~0.62 ka BP为3次明显的夏季风盛行、降水增多、生草成壤的相对暖湿气候;0.62 ka BP之后与现代气候状况相近。化学元素及其比值反映出毛乌素沙地具有千百年尺度的气候波动,并与北半球其他地区气候变化有着良好的对比。

关键词: 风成沉积, 常量化学元素, 气候变化, 全新世, 毛乌素沙地

Abstract: Located in the southeastern depression of the Ordos Plateau and the northwestern edge of the East Asian monsoon, Mu Us Desert is sensitive to climate change and has a vulnerable ecological environment. It has always been an ideal place to research climate change and desert evolution. The Daliuta (DLT) Profile(39°15'14″ N、111°15'08″ E)in Shenmu County, locating in the eastern Mu Us Desert, has developed representative eolian sand-paleosoil or eolian sand-lacustrine sedimentary sequence. Through analyzing the sediments in DLT Profile, based on data of OSL dating, geochemical major element oxides and the ratio of these elements, in combination with magnetic susceptibility, it was revealed that influenced by the East Asian monsoon, the regional climate has warmed overall since the Holocene, while there was still instability. The results showed that:(1) The sediment of DLT Profile is mainly composed of SiO2 and Al2O3, accounting for 69.72%~81.40.and 11.04%~12.71%, respectively; the major element oxides' contents are in order:SiO2 > Al2O3 > K2O > Na2O > Fe2O3 > MgO > CaO. There are differences among the contents of different sedimentary facies. Chemical activity of different geochemical elements shows obvious variability:K, Na are highly active, easy to enrich under the dry-cold climate and belonging aeolian sand; Ca and Mg are easily enriched in semi-arid and semi-humid areas; Si is relatively stable and contains a large amount in aeolian sand; Fe and Al are less active and enriched in paleosol indicating warm-humid climate. (2) The analysis of the correlation among major element oxides and the <63 μm silt and clay composition and magnetic susceptibility shows that there is a significant positive correlation among silt and clay composition, magnetic susceptibility and Al2O3, Fe2O3 and MgO; the more the content of silt and clay composition, the easy the Al2O3, Fe2O3 and MgO adsorbing and enriching, and the high the magnetic susceptibility (Xlf), indicating that the climate is relatively warm and humid; otherwise, it indicates a relatively dry and cold climate. (3) In the southeastern Mu Us Desert, there has been many times of climate change since the Holocene. Before 10.39 ka BP, climate has fluctuated frequently. The characteristics of the profile has showed alternating deposition of aeolian sand and lake-swamp. During 10.39~9.34 ka BP, 8.68~8.29 ka BP and 2.72~1.34 ka BP, winter monsoon had enhanced and cold-dry climate with strong winds had prompted intense aeolian activities so the desert had experienced a strong wind-sand activity period. From 9.34~8.68 ka BP, 8.29~2.72 ka BP and 1.34~0.62 ka BP, under the background of increasing temperature and humidity, sand dunes had fixed and soil had developed. After 0.62 ka BP, the climate has closed to the modern climate. Besides, the differences of geochemical major element oxides and ratio have influenced by winter and summer monsoon of East Asia, reflected the millennium to centuries scale climate change, which is regional response to global climate change.

Key words: eolian deposit, geochemical major elements, climate change, Holocene, Mu Us Desert

中图分类号: 

  • P539.3