Li Yun, Song Yougui, Yan Libin, Chen Tao, An Zhisheng
State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China.
State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China; Joint Center for Global Change Studies, Beijing 100875, China.
PLoS One. 2015 May 13;10(5):e0125492. doi: 10.1371/journal.pone.0125492. eCollection 2015.
Central Asia is one of the most significant loess regions on Earth, with an important role in understanding Quaternary climate and environmental change. However, in contrast to the widely investigated loess deposits in the Chinese Loess Plateau, the Central Asian loess-paleosol sequences are still insufficiently known and poorly understood. Through field investigation and review of the previous literature, the authors have investigated the distribution, thickness and age of the Xinjiang loess, and analyzed factors that control these parameters in the Xinjiang in northwest China, Central Asia. The loess sediments cover river terraces, low uplands, the margins of deserts and the slopes of the Tianshan Mountains and Kunlun Mountains and are also present in the Ili Basin. The thickness of the Xinjiang loess deposits varies from several meters to 670 m. The variation trend of the sand fraction (>63 μm) grain-size contour can indicate the local major wind directions, so we conclude that the NW and NE winds are the main wind directions in the North and South Xinjiang, and the westerly wind mainly transport dust into the Ili basin. We consider persistent drying, adequate regional wind energy and well-developed river terraces to be the main factors controlling the distribution, thickness and formation age of the Xinjiang loess. The well-outcropped loess sections have mainly developed since the middle Pleistocene in Xinjiang, reflecting the appearance of the persistent drying and the present air circulation system. However, the oldest loess deposits are as old as the beginning of the Pliocene in the Tarim Basin, which suggests that earlier aridification occurred in the Tarim Basin rather than in the Ili Basin and the Junggar Basin.
中亚是地球上最重要的黄土地区之一，在理解第四纪气候和环境变化方面具有重要作用。然而，与中国黄土高原广泛研究的黄土沉积不同，中亚黄土-古土壤序列仍然了解不足且认识有限。通过野外调查和对以往文献的回顾，作者研究了新疆黄土的分布、厚度和年代，并分析了中国西北、中亚地区新疆控制这些参数的因素。黄土沉积物覆盖了河流阶地、低地、沙漠边缘以及天山和昆仑山的山坡，伊犁盆地也有分布。新疆黄土沉积厚度从几米到670米不等。砂粒（>63μm）粒度等值线的变化趋势可以指示当地的主要风向，因此我们得出结论，西北风与东北风是新疆南北的主要风向，西风主要将沙尘输送到伊犁盆地。我们认为持续干旱、充足的区域风能和发育良好的河流阶地是控制新疆黄土分布、厚度和形成年代的主要因素。新疆出露良好的黄土剖面主要形成于中更新世以来，反映了持续干旱和现代大气环流系统的出现。然而，塔里木盆地最古老的黄土沉积与上新世初期一样古老，这表明塔里木盆地比伊犁盆地和准噶尔盆地更早发生了干旱化。
