Holocene loess sedimentation along the Qilian Shan (China): significance for understanding the processes and timing of loess deposition
Holocene loess sedimentation along the Qilian Shan (China): significance for understanding the processes and timing of loess deposition
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DOI：
10.1016/j.quascirev.2005.03.003
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发表时间：
2006
影响因子：
4
通讯作者：
Y. Küster;R. Hetzel;M. Krbetschek;Mingxin Tao
中科院分区：
文献类型：
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作者：
Y. Küster;R. Hetzel;M. Krbetschek;Mingxin Tao
我们展示了祁连山沿线保存完好的黄土沉积物的光年龄，祁连山是一条 500 公里长的山带，形成了青藏高原构造活动活跃的东北边缘。通过对粗粒（90-160μm）石英样品应用单等份再生（SAR）技术，对石游河和白涌河沿岸构造控制的充填台地的黄土进行了测年。对多矿物细粒（5-10μm）样品进行了额外的测量，以便对当前使用的各种光学测年技术进行比较。结果表明：（i）黄土堆积开始于距今 13 至 11ka 之间，并持续至今；（ii）平均黄土堆积速率范围在 ∼9 至 ∼16cmka−1 之间；（iii）全新世黄土不仅限于某些地点，而是沿祁连山山麓的普遍现象。晚更新世时期黄土沉积的缺乏是寒冷干燥的气候条件、强风以及末次冰河期缺乏植被覆盖的综合结果。只有在全新世开始时，气候变得更加温暖和湿润，植物覆盖才开始发展，起到了灰尘捕集器的作用，从而开始了黄土的形成。
We present optical ages for well preserved loess deposits along the Qilian Shan, a 500-km-long mountain belt forming the tectonically active northeastern margin of the Tibetan Plateau. Loess on tectonically controlled fill terraces along the Shiyou and Baiyong rivers was dated by applying the single-aliquot regeneration (SAR) technique to coarse-grained (90–160μm) quartz samples. Additional measurements on polymineralic fine-grained (5–10μm) samples were carried out to allow a comparison between various optical dating techniques currently in use. The results demonstrate that (i) loess accumulation started between 13 and 11ka B.P., continuing to the present, (ii) mean loess accumulation rates range between ∼9 and ∼16cmka−1, and (iii) Holocene loess is not restricted to certain sites only, but is a prevalent phenomenon along the Qilian Shan mountain front. The absence of loess deposits of Late Pleistocene age is a result of a combination of cold and dry climate conditions, strong winds, and the absence of a vegetation cover during the last glacial period. Only with the change to a warmer and moister climate at the onset of the Holocene did a plant cover develop, which acted as a dust trap, thus initiating the formation of loess.