Advance–retreat history of the East-Asian summer monsoon rainfall belt over northern China during the last two glacial–interglacial cycles
Advance–retreat history of the East-Asian summer monsoon rainfall belt over northern China during the last two glacial–interglacial cycles
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DOI：
10.1016/j.epsl.2008.08.001
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发表时间：
2008-10
影响因子：
5.3
通讯作者：
Shiling Yang;Z. Ding
中科院分区：
文献类型：
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作者：
Shiling Yang;Z. Ding
在中国北方，沙漠迁移的历史提供了一个很好的措施，东亚夏季风的变化，因为沙漠边缘环境是非常敏感的夏季风降水的变化。沙漠边缘的迁移可以很好地记录在下风黄土沉积中，因为中国黄土的粒度主要受源-汇距离的控制，因此黄土粒度是重建东亚夏季风历史的有效替代物。为了研究过去两次冰期-间冰期旋回中北方夏季风降水带的格局和迁移，绘制了MIS 2、3、4、5、6和7黄土粒度等值线图。冰川期和间冰期的粒度等值线均呈现出近南北向的梯度，表明黄土高原主体地区的沙尘沉积物主要来源于北部，并存在近南北向的沙尘输送通道，至少在过去两个冰期-间冰期旋回中是如此。MIS 2、3、4、5、6和7重建的东南沙漠边缘与现代等雨量线大致平行，这意味着东亚夏季风降水带在过去两次冰期-间冰期旋回中的格局与现代相似，即尽管存在冰期-间冰期旋回，夏季风等雨量线仍呈东北-西南走向。以MIS 2的粒度等值线为参考，得出MIS 3、4、5和7的沙漠向北后退距离分别为160、119、1225和1223 km，MIS 6的沙漠向南推进距离为129 km，这可初步作为东亚夏季风降水带的相对迁移距离。此外，MIS 3中推断的气候条件是中国北方凉爽潮湿，而最后两个冰期的最干最冷间隔出现在MIS 6中。
In northern China, the history of desert migration provides a good measure of the East-Asian summer monsoon variations, since the desert margin environment is very sensitive to changes in summer monsoon rainfall. Desert margin migration can be well documented in the downwind loess deposits, since the grain size of Chinese loess is principally controlled by source-to-sink distance and hence the loess grain size is an effective proxy for reconstructing the history of the East-Asian summer monsoon. In order to investigate the pattern and migration of the summer monsoon rainfall belt over northern China during the past two glacial–interglacial cycles, contour maps of loess grain size were constructed for MIS 2, 3, 4, 5, 6 and 7. All the grain-size isolines show a near north–south gradient for both glacials and interglacials, indicating a dominant dust source region in north and an approximately north–south dust transport pathway for dust deposits in the main body of the Loess Plateau, at least for the past two glacial–interglacial cycles. The reconstructed southeast desert margin for MIS 2, 3, 4, 5, 6 and 7 roughly parallels the present isohyets, implying that the pattern of the East-Asian summer monsoon rainfall belt during the past two glacial–interglacial cycles is similar to the present, i.e. a northeast–southwest trend for the isohyets of the summer monsoon, despite the glacial–interglacial cycles. Using the grain-size isolines of MIS 2 as a reference, we derive a northerly desert retreat of ∼160 km, ∼19 km, ∼225 km and ∼223 km for MIS 3, 4, 5 and 7, respectively, and a southerly desert advance of ∼29 km for MIS 6, that could be preliminarily regarded as the relative migration distance for the East-Asian summer monsoon rainfall belt. In addition, the inferred climate conditions in MIS 3 are cool and humid in northern China, while the driest and coldest interval of the last two glacial periods occurs in MIS 6.