Oxygen isotope signatures of quartz from major Asian dust sources: Implications for changes in the provenance of Chinese loess
Oxygen isotope signatures of quartz from major Asian dust sources: Implications for changes in the provenance of Chinese loess
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DOI：
10.1016/j.gca.2014.04.043
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发表时间：
2014-08
影响因子：
5
通讯作者：
Yan Yan-Yan;Youbin Sun;Hongyun Chen;Long Ma
中科院分区：
文献类型：
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作者：
Yan Yan-Yan;Youbin Sun;Hongyun Chen;Long Ma
本文系统地研究了来自蒙古戈壁、中国北方沙漠、塔克拉玛干沙漠和柴达木盆地等东亚主要沙尘源区的石英细颗粒和粗颗粒（<16和16-63 μm）的氧同位素组成。结果表明，塔克拉玛干沙漠和蒙古戈壁的石英氧同位素比值具有较强的不均一性。不同来源的细粒级和粗粒级石英δ ~（18）O值有不同程度的重叠，难以区分。从蒙古戈壁到北方沙漠再到塔克拉玛干沙漠，石英δ 18 O值都呈现出逐渐增大的趋势。这意味着源区的地质背景不同，从而导致高温火成岩的贡献不同。石英δ 18 O结果与其它石英基物源示踪物相结合，可以清楚地区分三个主要源区，塔克拉玛干沙漠、蒙古戈壁和中国北方沙漠。此外，我们的结果与以前的δ 18 O测量的细颗粒石英从洛川黄土序列的比较表明，可能的冰期-间冰期波动的灰尘来源。最后，我们认为，石英δ 18 O的签名和其他粉尘物源示踪剂的组合，可以潜在地提高中国黄土-红粘土矿床的物源的长期波动的认识。
We present a systematic investigation of the oxygen isotopic composition of quartz in both fine and coarse fractions (<16 and 16–63 μm) from major dust source regions in East Asia, including the Mongolian Gobi, the northern Chinese deserts, the Taklimakan desert, and the Qaidam Basin. The results demonstrate that the quartz oxygen isotope ratios of the Taklimakan desert and the Mongolian Gobi are more heterogeneous compared with the other areas. The quartz δ18O values of both the fine and coarse fractions from the various sources are overlapped to varying degrees, thus making it difficult to differentiate them. Nevertheless, the quartz δ18O values of both fractions exhibit an increasing trend from the Mongolian Gobi, to the northern Chinese deserts, and then to the Taklimakan desert. This implies that the geological settings of the source areas are different, which in turn results in differing contributions of high-temperature igneous rocks. The combination of quartz δ18O results with other quartz-based provenance tracers can clearly differentiate the three major source areas, i.e., the Taklimakan desert, the Mongolian Gobi, and the northern Chinese deserts. In addition, comparison of our results with previous δ18O measurements of fine-grained quartz from the Luochuan loess sequence suggests the likely glacial–interglacial fluctuations in dust provenance. Finally, we suggest that the combination of quartz δ18O signatures and other dust provenance tracers can potentially improve the recognition of long-term fluctuations in the provenance of Chinese loess-red clay deposits.