中国毛乌素沙漠全新世湖泊化学风化强度变化记录
A Holocene lacustrine record of variations in chemical weathering intensity in the Mu Us Desert, China.
作者信息
Li Yijing, Liu Xiaokang, Pang Jiangli, Ding Zhiyong, Yue Xiaoxiao, Yang Xingdi, Zhao Yixue, Dong Zhibao
机构信息
School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China.
School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China; Engineering Center of Desertification and Blown-Sand Control of Ministry of Education, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; Planetary Aeolian Research Institute, Shaanxi Normal University, Xi'an 710119, China.
出版信息
Sci Total Environ. 2023 Dec 10;903:166281. doi: 10.1016/j.scitotenv.2023.166281. Epub 2023 Aug 14.
The Mu Us Desert is an ideal location to study environmental changes during the Late Quaternary, because of its unique characteristics. The Abaoyan (ABY) profile, a typical aeolian-lacustrine profile located at the eastern edge of the desert, was investigated in this study. A basic chronological framework was established based on a combination of radiocarbon dating by accelerator mass spectrometry and in situ sedimentary phase identification. Furthermore, changes in regional chemical weathering intensity since the Holocene were evaluated through comprehensive analysis of the collected samples in terms of grain size, loss on ignition (LOI), chromaticity, geochemical element contents, and soil micromorphology. The results showed that the ABY profile was under the influence of primary and moderate chemical weathering. Regional paleoclimatic environmental changes could be divided into four stages. During Stage I (before 12.6 ka BP; pre-Holocene), the ABY profile was dominated by aeolian sand, showing a coarse average grain size, low LOI, and high chromaticity values, which may have indicated a dry and cold period. During Stage II (12.6-10.3 ka BP; early Holocene), the ABY profile was dominated by lacustrine sediments, indicating a shallow lake water environment with strong chemical weathering and a warm and humid climate. During Stage III (10.3-4.2 ka BP), the profile was dominated by sandy peat deposits with a relatively large proportion of clay particles suggesting that the intensity of chemical weathering was relatively strong in the region during this period and the climate was mainly warm and humid. During Stage IV (after 4.2 ka BP), the sediment was dominated by aeolian sand and secondary loess, the chromaticity increased, the LOI reduced, and the regional chemical weathering intensity was weaker. The change in chemical weathering intensity in this region was inferred to be a positive response to the Holocene East Asian monsoon circulation.
毛乌素沙漠因其独特的特征，是研究晚第四纪环境变化的理想地点。本研究对位于沙漠东缘的典型风成 - 湖相剖面阿保岩（ABY）剖面进行了调查。基于加速器质谱放射性碳测年和原位沉积相识别相结合的方法，建立了一个基本的年代学框架。此外，通过对采集样本的粒度、烧失量（LOI）、色度、地球化学元素含量和土壤微形态等方面的综合分析，评估了全新世以来区域化学风化强度的变化。结果表明，ABY剖面受初级和中等化学风化的影响。区域古气候环境变化可分为四个阶段。在第一阶段（12.6 ka BP之前；全新世前），ABY剖面以风成沙为主，平均粒度粗，烧失量低，色度值高，这可能表明是一个干旱寒冷时期。在第二阶段（12.6 - 10.3 ka BP；全新世早期），ABY剖面以湖相沉积物为主，表明是一个浅湖水环境，化学风化强烈，气候温暖湿润。在第三阶段（10.3 - 4.2 ka BP），剖面以含砂泥炭沉积为主，粘土颗粒比例相对较大，表明该时期区域化学风化强度相对较强，气候主要为温暖湿润。在第四阶段（4.2 ka BP之后），沉积物以风成沙和次生黄土为主，色度增加，烧失量降低，区域化学风化强度较弱。推断该区域化学风化强度的变化是对全新世东亚季风环流的积极响应。
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