Magnetic, granulometric and geochemical characterizations of loess sections in the eastern Arid Central Asia: Implication for paleoenvironmental interpretations
Magnetic, granulometric and geochemical characterizations of loess sections in the eastern Arid Central Asia: Implication for paleoenvironmental interpretations
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DOI：
10.1016/j.quaint.2020.01.003
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发表时间：
2020-01
影响因子：
2.2
通讯作者：
Guanhua Li;D. Xia;Hao Lu;Youjun Wang;J. Jia;Xianbin Liu;Xiaoqiang Yang
中科院分区：
文献类型：
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作者：
Guanhua Li;D. Xia;Hao Lu;Youjun Wang;J. Jia;Xianbin Liu;Xiaoqiang Yang
中亚干旱地区（ACA）的黄土沉积包含有关西风带演变和亚洲内陆干旱化的敏感信息。通过对黄土剖面的地球物理和地球化学特征的综合研究，探讨了晚更新世以来的古气候变化。结果表明，ACA黄土主要表现出与中国黄土高原等地区黄土沉积相似的地球物理和地球化学成分。有不同的积累率，将负责ACA黄土剖面内的沉积差异。此外，本研究中的块状颗粒和地球化学代用指标存在三种磁响应。在剖面的底部，磁性增强与粗粒度和水淋溶有关。磁增强响应较强的成壤作用和中等的古风强度的最上部。此外，在剖面的中部存在一个过渡段，其特征是碎屑输入不协调，成壤作用较弱。因此，可以通过不同沉积阶段来评价ACA黄土的磁性气候学。此外，这项研究总体上表明，在ACA的古气候模式可能是以相对低的水分在温暖的间隔，反之亦然，在中部和底部的配置文件。但相对增强的水分在全新世时期表示。进一步的研究仍然是必要的，以获得可靠的代理和年代学的详细古气候解释的ACA黄土。
Loess deposits in the Arid Central Asia (ACA) contain sensitive messages concerning the evolution of the Westerlies and the interior aridification of Asia. In this study, we conducted a combined study of geophysical and geochemical characterization on loess sections in the eastern ACA, to discuss possible paleoclimate development since the late Pleistocene Era. Results show that the ACA loess chiefly exhibited similar geophysical and geochemical compositions with loess deposits in other regions, like the Chinese Loess Plateau. There are various accumulation rates that would have been responsible for the depositional difference within the ACA loess profiles. In addition, there are three magnetic responses to the bulk grains and geochemical proxies in this study. At the bottom segment of the section, magnetic enhancement was associated with coarse grain sizes and water leaching. Magnetic enhancement responded to stronger pedogenesis and moderate paleo-wind intensity in the uppermost parts. Moreover, there is a transitional segment in the middle part of the section, characterized by inordinately detrital inputs and weak pedogenic contributions. Thus, it may be better to evaluate the magnetic climatology of the ACA loess through different depositional stages. Furthermore, this study generally reveals that the paleoclimate pattern in the ACA was probably characterized by relatively low moisture during warm intervals, and vice versa, in the middle and bottom parts of the profiles. But relatively enhanced moisture was indicated during the Holocene period. Further studies are still necessary to obtain reliable proxies and chronology for a detailed paleoclimate interpretation of the ACA loess.