| 青海湖湖东沙地河湖-风成沉积记录的中晚全新世以来环境变化 |
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| 引用本文： | 陈东雪,鲁瑞洁,丁之勇,刘小槺.青海湖湖东沙地河湖-风成沉积记录的中晚全新世以来环境变化[J].中国沙漠,2021,41(6):99-110. |
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| 作者姓名： | 陈东雪 鲁瑞洁 丁之勇 刘小槺 |
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| 作者单位： | 1.北京师范大学 地理科学学部 防沙治沙教育部工程研究中心/地表过程与资源生态国家重点实验室，北京 100875;2.陕西师范大学 地理科学与旅游学院，陕西 西安 710119 |
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| 基金项目： | 国家重点研发计划项目(2017YFC1502401);国家自然科学基金项目(41901094) |
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| 摘 要： | 青海湖盆地因其独特的地理位置和气候环境，对气候变化响应敏感，是研究环境变化重要的场所。本研究在青海湖湖东沙地获取两个剖面，采用AMS14C测年，结合岩性、粒径组分和常量元素氧化物及其比值等多指标分析方法，重建了湖东沙地8.4 ka BP以来的环境演变过程。结果表明：除少量沉积物处于中等化学风化阶段外，大部分沉积物处于物理风化和初级化学风化阶段，说明自8.4 ka BP以来研究区气候环境总体上相对寒冷干燥。在千年尺度上，研究区不同时间段的气候环境存在较大的差异。8.4—4.2 ka BP气候相对温暖湿润；其中，8.4—6.2 ka BP河湖相和风成相沉积互层，表明存在明显的百年尺度气候波动；6.2—4.2 ka BP化学风化和淋溶作用较强，表明季风降水较多，径流较强，发育了较为稳定的湖泊沉积环境。4.2 ka BP以来湖泊消失，化学风化和淋溶作用减弱，沉积物从砾石转变为砂质黄土，显示气候较为冷干且波动较大。对比分析表明，中晚全新世以来青海湖湖东沙地的气候变化特征与东亚季风边缘区其他区域基本一致，并主导了区域沉积环境的演变过程。
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| 关 键 词： | 青海湖湖东沙地 中晚全新世 元素地球化学 古气候 河湖-风成沉积 |
| 收稿时间： | 2021-05-10 |
| 修稿时间： | 2021-07-07 |
Mid-late Holocene environmental changes recorded by fluvio-lacustrine and aeolian sediments in the eastern sandy land of Qinghai Lake |
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| Dongxue Chen,Ruijie Lu,Zhiyong Ding,Xiaokang Liu.Mid-late Holocene environmental changes recorded by fluvio-lacustrine and aeolian sediments in the eastern sandy land of Qinghai Lake[J].Journal of Desert Research,2021,41(6):99-110. |
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| Authors: | Dongxue Chen Ruijie Lu Zhiyong Ding Xiaokang Liu |
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| Institution: | 1.MOE Engineering Reaearch Center of Desertification and Blown-Sand Control / State Key Laboratory of Earth Surface Processes and Resource Ecology，Faculty of Geographical Science，Beijing Normal University，Beijing 100875，China;2.School of Geography and Tourism，Shaanxi Normal University，Xi’an 710119，China |
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| Abstract: | The numerous deposits in the eastern sandy land of Qinghai Lake recorded wealthy information of regional paleoclimate and paleoenvironmental since the Holocene. However， controversy still remains in regional climate and environmental changes on the millennial-scale. In this study， we explored aeolian deposits from the Sandaotan （SDT） and Dashuitangzuoan （DSTK） profiles in the eastern Qinghai Lake. Eight conventional radiocarbon dates were utilized to construct chronological frameworks. Furthermore， a multi-index analysis method of lithology， particle size， and major chemical element oxides with their ratios was conducted to reconstruct the environmental evolution process in study area over the past 8.4 ka BP. The results reveal that most of the sediments are at the physical weathering and primary chemical weathering stages except for a small number of sediments reach medium chemical weathering stage， which indicates that the climatic environment in the study area has been getting drier since 8.4 ka BP. Whereas evidence from the analysis of each index suggest that there are significant differences of climatic environment in different periods on the millennial-scale. Compared with other periods， the climate was warmer and more humid during 8.4-4.2 ka BP. Among that the aeolian sand interlayer appeared in the lacustrine sediments， indicating obvious centennial-scale climatic fluctuations during 8.4-6.2 ka BP； the great chemical weathering and leaching condition occurred from 6.2 to 4.2 ka BP， indicating relatively warm and humid climate conditions and the stable lacustrine sediment. After 4.2 ka BP， gravel accumulated in sandy loess deposit， and finally weakly paleosol deposit. Moreover， the comparative analysis shows that the climate change characteristics of the eastern sandy land in Qinghai Lake are consistent with other regions in the East Asian monsoon marginal region. Highlight the climate change dominate the evolution process of the regional sedimentary environment since the mid-late Holocene. |
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| Keywords: | the eastern sandy land of Qinghai Lake mid-late Holocene elemental geochemistry paleoclimate fluvio-lacustrine and aeolian deposit |
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