High-resolution enviromagnetic records of the last deglaciation from Dali Lake, Inner Mongolia
High-resolution enviromagnetic records of the last deglaciation from Dali Lake, Inner Mongolia
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DOI：
10.1016/j.palaeo.2016.04.030
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发表时间：
2016-07
期刊：
影响因子：
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通讯作者：
Suzhen Liu;C. Deng;Jule Xiao;Jinhua Li;G. Paterson;Liao Chang;L. Yi;H. Qin;R. Zhu
中科院分区：
文献类型：
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作者：
Suzhen Liu;C. Deng;Jule Xiao;Jinhua Li;G. Paterson;Liao Chang;L. Yi;H. Qin;R. Zhu
末次消冰期的详细古气候记录对于理解极端变化条件下的快速气候变化及其机制具有重要价值。由于东亚半干旱地区对气候变率的敏感性和对人类居住的重要性，高分辨率古气候研究是必不可少的。对内蒙古中部大理湖15.90 ~ 11.46 ka的沉积层序进行了高分辨率环境磁调查。通过岩心沉积物和集水区样品的综合岩石磁性分析，结合扫描电子望远镜、透射电子望远镜观测和x射线衍射分析，确定了变磁性矿物来源。研究岩心被磁性划分为4个单元：1单元（11.83 ~ 11.5 m, 15.90 ~ 15.32 ka）的磁性矿物主要来源于集水区玄武岩的基岩侵蚀；这一时期对应于末次盛冰期之后的快速气候波动。在单元2 （11.50 ~ 9.50 m, 15.32 ~ 12.67 ka）和单元3 (9.50 ~ 8.59 m, 12.67 ~ 11.56 ka)，表层土壤侵蚀产生的伪单畴磁铁矿是主要的磁性载体。这两个单元分别与b ølling - allero ød暖期和新仙女木期冷期在时间误差范围内重合，并可与石笋和冰芯记录进行对比。我们的发现反映了湖泊集水区在寒冷和温暖时期的不同侵蚀过程，这些过程最终受到末次冰消期气候变化的控制。
Detailed paleoclimate records during the last deglaciation are highly valuable for understanding rapid climatic changes and mechanisms during extremely variable conditions. High-resolution paleoclimate research in the semi-arid East Asian interior is essential due to its sensitivity to climate variability and importance for human inhabitance. A high-resolution environmental magnetic investigation has been performed on a sedimentary sequence from Dali Lake in central Inner Mongolia, which covers the period of 15.90–11.46 ka. Variable magnetic mineral sources are identified based on integrated rock magnetic analysis of both core sediments and catchment samples, complemented by scanning electron telescope and transmission electron telescope observation and X-ray diffraction analysis. The studied core is magnetically divided into four units: Magnetic minerals in Unit 1 (11.83–11.5 m, 15.90–15.32 ka) are mainly sourced from bedrock erosion of basalts in the catchment. This period corresponds to rapid climate fluctuations after the Last Glacial Maximum. In Unit 2 (11.50–9.50 m, 15.32–12.67 ka) and Unit 3 (9.50–8.59 m, 12.67–11.56 ka), pseudo-single domain magnetites from erosion of surface soils are the main magnetic carriers. These two units coincide within time error with the Bølling–Allerød warm period and the Younger Dryas cold period, respectively, and can be correlated with stalagmite and ice core records. Our findings reflect contrasting erosion processes during cold and warm periods in the lake catchment, which were ultimately controlled by climate changes during the last deglaciation.