| 九江市蓼花剖面末次冰期中晚期沉积的粒度端元特征与气候变化 |
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| 引用本文： | 李世乾,李志文,周万蓬,杜丁丁,黎武标.九江市蓼花剖面末次冰期中晚期沉积的粒度端元特征与气候变化[J].热带地理,2023,43(1):135-143. |
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| 作者姓名： | 李世乾 李志文 周万蓬 杜丁丁 黎武标 |
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| 作者单位： | 1.东华理工大学 地球科学学院, 南昌 330013;2.佛山科学技术学院 环境与化学工程学院, 广东 佛山 528225;3.中国科学院地质与地球物理研究所, 北京 100029 |
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| 基金项目： | 国家自然科学基金项目(41201006);核资源与环境国家重点实验室开放基金项目(NRE1507) |
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| 摘 要： | 鄱阳湖湖滨地区广泛分布着晚第四纪风沙沉积序列。在星子县沙岭沙山进行野外调查后选择蓼花剖面开展工作，测试了地质时代和粒度，对粒度结果使用端元分析模型进行研究，探讨该区域末次冰期中晚期的气候变化规律。结果显示：该剖面由湖相-古土壤-沙丘砂等沉积相叠覆堆积组成，形成于末次冰期中晚期（48.8—17.1 ka）。端元分析模型将粒度数据分解出3个不同的粒度端元，不同端元组分在垂向上呈峰谷交替的旋回变化，EM1代表粉砂端元组分，峰值对应湖相和古土壤发育时期；EM2和EM3代表中砂—粗砂端元组分，峰值对应沙丘砂发育期，这些峰谷交替变化的规律指示了末次冰期的季风演变以及气候波动变化，万年尺度上表现为LH10 (48.8—39.9 ka)和LH3～LH5 (28.1—17.1 ka)的冬季风强盛期，分别对应深海氧同位素的MIS3b和MIS2阶段。LH6～LH9 (39.9—28.1 ka)为温暖的夏季风时期，对应深海氧同位素的MIS3a阶段。这些变化与YZ洞石笋氧同位素以及格陵兰冰心有良好的对应，与全球气候变化基本一致。
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| 关 键 词： | 九江市 蓼花剖面 末次冰期中晚期 粒度端元分析 季风演变 气候变化 |
| 收稿时间： | 2022-10-11 |
Climatic Changes in the Middle and Late Period of the Last Glacial Period in Liaohua Section of Jiujiang,Jiangxi Province Recorded by End-Member Grain Size |
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| Shiqian Li,Zhiwen Li,Wanpeng Zhou,Dingding Du,Wubiao Li.Climatic Changes in the Middle and Late Period of the Last Glacial Period in Liaohua Section of Jiujiang,Jiangxi Province Recorded by End-Member Grain Size[J].Tropical Geography,2023,43(1):135-143. |
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| Authors: | Shiqian Li Zhiwen Li Wanpeng Zhou Dingding Du Wubiao Li |
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| Institution: | 1.School of Earth Sciences, East China University of Technology, Nanchang 330013, China;2.School of Environmental and Chemical Engineering, Foshan University of Science and Technology, Foshan 528225, China;3.Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China |
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| Abstract: | Late Quaternary aeolian sediment sequences are widely distributed in the Poyang Lake area and are good subjects for climate evolution research. However, previous studies have focused mainly on aeolian sediments and less on lacustrine facies and their overlapping accumulation with aeolian sands. Therefore, after field investigations in Shaling Mountain, Xingzi County, the Liaohua section was selected as the study area where we tested the geological age and grain size, analyzed the grain size results by end-member analysis model, and compared the end-member component content with the average grain size and standard deviation. Oxygen isotopes of stalagmites in YZ Cave, Chongqing, and Greenland ice core records were analyzed. We also discussed the climate change law in the middle and late periods of the last glacial period in this area to source basic data for the response of the last glacial deposits in the Poyang Lake area to the East Asian monsoon and even the whole world. The results show the following: 1) This section is composed of lake facies, ancient soil, dune sand, and other sedimentary facies. Combined with the dating results and deep-sea oxygen isotope records, a chronological-depth framework based on the piecewise sedimentation rate interpolation method was constructed. The dating results show that this profile was formed in the middle and late glacial stage (48.8-17.1 ka) and the grain size was mainly silt, medium sand, and fine sand. Clay was higher in the paleosol or lacustrine layer, and coarse sand had the highest volume fraction in the dune sand layer. 2) The end-member analysis model separates the granularity data into three different granularity end-members ( EM1, EM2, and EM3). The contents of different end-member components in different strata are obviously different. EM1 represents the end-member components of silt, and the peak values correspond to the development period of lacustrine facies and paleosol. EM2 and EM3 represent the end-member components of medium sand and coarse sand, respectively, and the peak values correspond to the dune sand development period. 3) The end volume fraction and average particle size sorting coefficient show obvious peak-valley alternations on the profile, and the alternation of these peak-valley cycles represents monsoon evolution and climate fluctuation in the last glacial period. On the scale of 10,000 years, the strong winter monsoon periods are LH10 (48.8-39.9 ka) and LH3-LH5 (28.1-17.1 ka), which correspond to the peak areas of EM2 and EM3. Dune sand has a high coarse grain content, small standard deviation, and good sorting, corresponding to the MIS3b and MIS2 stages of deep-sea oxygen isotopes, respectively. LH6-LH9 (39.9-28.1 ka) is a warm summer monsoon period, corresponding to the peak area of EM1, lacustrine deposition and paleosol development, many fine particle components, large standard deviation, and poor sorting, which corresponds to the MIS3a stage of deep-sea oxygen isotopes. These changes correspond with the changes in oxygen isotopes of stalagmites in the YZ cave and Greenland ice cores, which is consistent with global climate change. |
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| Keywords: | Jiujiang city Liaohua section middle and late last glacial grain-size end-member analysis monsoon evolution climate change |
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