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干旱区地理 ›› 2021, Vol. 44 ›› Issue (2): 409-417.doi: 10.12118/j.issn.1000–6060.2021.02.12

• 地表过程研究 • 上一篇    下一篇

巴丹吉林沙漠东南缘末次冰期沉积物地球化学特征及气候指示意义

范小露1,2(),张新毅1,2(),田明中3   

  1. 1.阜阳师范大学历史文化与旅游学院地理系,安徽 阜阳 236037
    2.阜阳师范大学皖北文化研究中心,安徽 阜阳 236037
    3.中国地质大学(北京)地球科学与资源学院,北京 100083
  • 收稿日期:2019-10-03 修回日期:2019-12-25 出版日期:2021-03-25 发布日期:2021-04-14
  • 通讯作者: 张新毅
  • 作者简介:范小露(1987-),女,讲师,主要从事第四纪地质学与气候演变等方面的研究. E-mail:atsunnyshore@126.com
  • 基金资助:
    国家自然科学基金(41572094);阜阳师范大学青年人才基金重点项目(rcxm201907);阜阳师范大学科学研究项目(2018FSKJ08 ZD);阜阳师范大学博士科研启动基金(2016kyqd0004);安徽省高校人文社科重点研究基地阜阳师范大学皖北文化研究中心2020年度重点项目资助(SK2020A0311)

Geochemical characteristics and paleoclimatic significance of the last glacial sediments in the southeastern margin of Badain Jaran Desert

FAN Xiaolu1,2(),ZHANG Xinyi1,2(),TIAN Mingzhong3   

  1. 1. School of History Culture and Tourism, Fuyang Normal University, Fuyang 236037, Anhui, China
    2. The Center of Cultural Research in Northern Anhui, Fuyang Normal University, Fuyang 236037, Anhui, China
    3. School of Earth Science and Resource, China University of Geoscience, Beijing 100083, China
  • Received:2019-10-03 Revised:2019-12-25 Online:2021-03-25 Published:2021-04-14
  • Contact: Xinyi ZHANG

摘要:

沙漠古气候重建对于了解区域古气候演变具有重要意义。通过以巴丹吉林沙漠东南缘巴润宝日陶勒盖(BRBG)剖面为研究对象,进行全样地球化学、分组分分粒级元素地球化学及Sr同位素分析,重建该地区末次冰期期间(66.8~41.0βka)的气候演化模式。研究表明:66.8~41.0βka呈现残留组分高Sr/Ca值、酸溶组分及残留组分低Ba含量特征,指示化学风化增强及湖泊补给量增加,反映暖湿气候特征。微量元素变化特征指示沉积物细粒组分中的微量元素指标对气候的敏感度高于粗粒组分。Sr同位素结果显示酸溶组分中87Sr/86Sr值在66.8βka附近达到最大值,可能与湖水盐度升高相关。此外,几乎所有指标均指示在41.0βka前后存在一次气候突变事件,研究认为巴丹吉林沙漠东南缘41.0βka前后从暖湿突变为干冷气候可能是该时期的西伯利亚高压系统增强所致。

关键词: 末次冰期, 地球化学, 古气候, 西伯利亚高压, 巴丹吉林沙漠

Abstract:

Reconstructing the desert paleoclimate is critical for understanding paleoclimate evolution. As the third-largest desert in China, the Badain Jaran Desert’s mega dune is the highest in China and the world and unique for its crowded mega dunes. This region’s geology and environmental information are challenging to acquire. By using innovative methods and techniques to study the Badain Jaran Desert’s climate change, research will significantly influence climate studies in the northwest arid area and even East Asia. The climate evolution model during the last glacial period (66.8-41.0 ka) in the Barunbaoritaolegai (BRBG) section in the southeastern margin of the Badain Jaran Desert was reconstructed using whole-sample geochemistry, granular-scale element geochemistry, and Sr isotope analysis. During 66.8-41.0 ka, the residual components showed high Sr/Ca values, whereas acid-soluble and residual components showed low Ba contents, indicating enhanced chemical weathering and increased lake supply, reflecting the characteristics of a warm and humid climate. The trace element changes indicate that trace elements in the fine grain components of sediments are more sensitive to climate than the coarse ones. Although the geochemical indices from the entire sample show little obvious feedback, the other innovative technique used in this study suggests higher efficiency and more sensitivity to environmental variation. Therefore, this approach could be used in future studies on climate and environmental variation. Based on the experimental outputs, the K and Sr concentrations in the residual components of fine fraction (<125 μm), the Sr/Ca values of residual components of fine fraction (<125 μm), the K concentrations in the acid-soluble components of the coarse fraction (>125 μm), and the Al concentrations in both acid-soluble and residual components of the coarse fraction (>125 μm) are the typical sensitive chemical indicators of climate change. The research group found that fine-sized fractions in the sediments are sensitive to climate change, which is an ideal media to reflect environmental vibration. By introducing novel ideas to climate-related research, the team discovered that Ba variations in acid-soluble fractions are highly sensitive, whether in fine or coarse grain-sized sediments. The87Sr/86Sr ratio of sediments from the inland lake is a critical indicator of chemical weathering intensity. The ratio change in acid-dissolved components indicates a change in strontium in the deposition area, whereas the ratio change in residual components reflects a change in strontium in the source area. The opposite trend is evident for the strontium ratio, showing that the response of different sediment components to chemical weathering is different in the provenance and sedimentary regions. Sr isotope results show that the 87Sr/86Sr value reached a maximum at ~66.8 ka, which could be related to the increase in lake water salinity. Furthermore, most indicators show a sudden climate change at ~41.0 ka, and the study indicates that the abrupt change from warm wet climate to dry cold climate at ~41.0 ka in the southeastern margin of Badain Jaran Desert might be caused by the enhancement of a Siberian high-pressure system in this period.

Key words: last glacial period, geochemical, paleoclimate, Siberian high pressure system, Badain Jaran Desert