Late Plio-Pleistocene humidity fluctuations in the western Qaidam Basin (NE Tibetan Plateau) revealed by an integrated magnetic–palynological record from lacustrine sediments
Late Plio-Pleistocene humidity fluctuations in the western Qaidam Basin (NE Tibetan Plateau) revealed by an integrated magnetic–palynological record from lacustrine sediments
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DOI：
10.1016/j.yqres.2015.09.009
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发表时间：
2015-11
影响因子：
2.3
通讯作者：
C. Herb;A. Koutsodendris;Weilin Zhang;E. Appel;X. Fang;S. Voigt;J. Pross
中科院分区：
文献类型：
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作者：
C. Herb;A. Koutsodendris;Weilin Zhang;E. Appel;X. Fang;S. Voigt;J. Pross
青藏高原地区在上新世-更新世的气候演变的破译是阻碍了连续的档案和代理数据集指示水分的可用性。本文以柴达木盆地西部SG-1钻孔岩芯（2.69-0.08 Ma）为基础，对湖相沉积物磁化率（χ）作为古水文指标的适用性进行了评价。我们的评估是基于直接比较χ与蒿/藜科（A/C）花粉比，这是一个敏感的，完善的代理干旱环境中的水分变化。我们发现，较高和较低的χ值分别代表干燥和不太干燥的条件下，晚上新世更新世。少干阶段可能是由短暂增加的西风带的影响和/或减少亚洲冬季风的影响，冰川间冰期的时间尺度。这种关系的一个例外是~ 1.9 Ma和1.3 Ma之间，此时SG-1 χ记录表现出54 ka的周期性，这可能表明该时期夏季风对柴达木盆地的影响。1.3Ma后，由于全球变冷，夏季风的影响可能已经停止，亚洲冬季风和西风带对柴达木盆地水文的控制作用增强。
Deciphering the climatic evolution of the Tibetan Plateau region during the Plio-Pleistocene is hampered by the lack of continuous archives and proxy datasets indicative of moisture availability. Here we assess the suitability of magnetic susceptibility (χ) measured on lacustrine sediments as a paleohydrological proxy based on material from drill core SG-1 (2.69–0.08 Ma) from the western Qaidam Basin. Our assessment is based on directly comparing χ with the Artemisia/Chenopodiaceae (A/C) pollen ratio, which represents a sensitive, well-established proxy for moisture changes in arid environments. We find that higher and lower χ values represent drier and less dry conditions, respectively, for the Late Plio-Pleistocene. Less dry phases were likely caused by transiently increased influence of the westerlies and/or decreased influence of the Asian winter monsoon on glacial–interglacial time scales. An exception from this relationship is the interval between ~ 1.9 and 1.3 Ma, when the SG-1 χ record exhibits a 54 ka cyclicity, which may indicate summer monsoon influence on the Qaidam Basin during that time. After ~ 1.3 Ma, the summer monsoon influence may have ceased due to global cooling, with the consequence that the Asian winter monsoon and the westerlies exerted a stronger control on the hydrology of the Qaidam Basin.