Shifting material source of Chinese Loess since ~2.7 Ma reflected by Sr isotopic composition.
Shifting material source of Chinese Loess since ~2.7 Ma reflected by Sr isotopic composition.
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自〜2.7 mA以SR同位素组成反映的中国黄土的材料来源。
DOI：
10.1038/srep10235
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发表时间：
2015-05-21
影响因子：
4.6
通讯作者：
Li G
中科院分区：
文献类型：
--
作者：
Zhang W;Chen J;Li G
破译中国黄土高原风成尘的来源，是重建古风型和古环境变化的基础。现有的数据集显示，无论是在轨道时间尺度上还是在构造时间尺度上，CLP上风尘的来源演变都相互矛盾。本文测定了一个受限粒度组分(28~45 μm)的硅酸盐锶、钕同位素组成，以追踪~2.7 Ma以来的源区演化。我们的结果显示，在过去的2.7 Ma期间，震源在轨道时间尺度上没有变化，但震源从祁连山逐渐转移到戈壁阿尔泰山。构造抬升和气候变化可能在这一转变中发挥了重要作用。5 ± 3 Ma以来，戈壁-阿尔泰山相对祁连山的晚期隆升，可能是戈壁物质对阿拉善干旱区源区沙漠贡献增大的原因。增强的冬季季风也可能有助于将戈壁材料从阿拉善干旱地区输送到中电。亚洲尘埃来源的转变也反映在北太平洋的沉积物中。在根据风成沉积物的来源敏感指标解释长期气候变化时，这种来源变化的发现需要谨慎。
Deciphering the sources of eolian dust on the Chinese Loess Plateau (CLP) is fundamental to reconstruct paleo-wind patterns and paleo-environmental changes. Existing datasets show contradictory source evolutions of eolian dust on the CLP, both on orbital and tectonic timescales. Here, the silicate Sr and Nd isotopic compositions of a restricted grain size fraction (28–45 μm) were measured to trace the source evolution of the CLP since ~2.7 Ma. Our results revealed an unchanged source on orbital timescales but a gradual source shift from the Qilian Mountains to the Gobi Altay Mountains during the past 2.7 Ma. Both tectonic uplift and climate change may have played important roles for this shift. The later uplift of the Gobi Altay Mountains relative to the Qilian Mountains since 5 ± 3 Ma might be responsible for the increasing contribution of Gobi materials to the source deserts in Alxa arid lands. Enhanced winter monsoon may also facilitate transportation of Gobi materials from the Alxa arid lands to the CLP. The shifting source of Asian dust was also reflected in north Pacific sediments. The finding of this shifting source calls for caution when interpreting the long-term climate changes based on the source-sensitive proxies of the eolian deposits.