Stepwise expansion of desert environment across northern China in the past 3.5 Ma and implications for monsoon evolution
Stepwise expansion of desert environment across northern China in the past 3.5 Ma and implications for monsoon evolution
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DOI：
10.1016/j.epsl.2005.06.036
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发表时间：
2005-08-30
影响因子：
5.3
通讯作者：
Liu, TS
中科院分区：
文献类型：
--
作者：
Ding, ZL;Derbyshire, E;Liu, TS
对中国黄土高原三个断面末次冰期周期的系统研究表明，黄土中砂粒含量自北向南迅速减少，黄土层位砂粒含量显着高的现象仅出现在黄土高原北部地区。这表明，沙漠边缘附近黄土中沙粒比例的变化与中国北部沙漠南部边界的迁移密切相关，其中沙粒在地表附近主要以跃移或改良跃移模式移动。由于沙漠边缘的变化本质上是由季风降水量控制的，因此沙漠边缘附近黄土中沙子大小的颗粒含量被认为是东亚夏季风强度变化的新且易于应用的指标。黄土-沙漠过渡带黄土含沙量的连续记录表明，毛乌素沙漠在2.6、1.2、0.7和0.2Ma时向南迁移，表明近3.5Ma东亚夏季风逐步减弱。这种演化模式与之前根据黄土磁化率记录（一种广泛使用的季风代理）推断的演化模式显着不同。我们的研究结果进一步表明，全球冰量的变化可能是控制上里奥-更新世季风演化的重要因素，并且预计未来极地冰盖的融化可能导致中国北方季风降雨带向北迁移。 (c) 2005 Elsevier B.V. 保留所有权利。
A systematic study of the last glacial cycle along three transects across the Chinese Loess Plateau shows that sand-sized particle content within loess decreases rapidly from north to south, and that markedly high sand particle contents in loess horizons occur only in the northern part of the Plateau. This suggests that variation in the sand-sized particle fraction within loess near the desert margin is closely linked to migration of the southern desert border in northern China where sand grains move mainly in saltation or modified saltation mode near the ground surface. As desert margin shift is essentially controlled by the amount of monsoon precipitation, the sand-sized particle content within loess near desert margin is regarded as a new and readily applied proxy for variations in the strength of the East-Asian summer monsoon. A continuous record of sand content in loess along the loess-desert transitional zone shows that the Mu Us Desert migrated southward at 2.6, 1.2, 0.7 and 0.2 Ma, suggesting a stepwise weakening of the East-Asian summer monsoon during the past 3.5 Ma. This evolutionary pattern is significantly different from that previously inferred from loess magnetic susceptibility records, a widely used monsoon proxy. Our results further suggest that changes in global ice volume may have been an essential factor in controlling Plio-Pleistocene monsoon evolution, and that the anticipated future melting of polar ice cover may lead to a northward migration of the monsoon rainfall belt in northern China. (c) 2005 Elsevier B.V. All rights reserved.