中国沙漠 ›› 2019, Vol. 39 ›› Issue (2): 86-95.DOI: 10.7522/j.issn.1000-694X.2018.00058

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基于粒度数据重建的近2 000 a新疆博斯腾湖区域风沙活动

周刚平, 黄小忠, 王宗礼, 张军, 谢海超   

  1. 兰州大学 资源环境学院/西部环境教育部重点实验室, 甘肃 兰州 730000
  • 收稿日期:2018-03-28 修回日期:2018-05-02 发布日期:2019-04-11
  • 通讯作者: 黄小忠(
  • 作者简介:周刚平(1991-),男,四川达州人,硕士研究生,研究方向为湖泊沉积学与环境变化。
  • 基金资助:

Eolian Activity History Reconstructed by Bosten Lake Grain Size Data over the Past~2 000 Years

Zhou Gangping, Huang Xiaozhong, Wang Zongli, Zhang Jun, Xie Haichao   

  1. College of Earth and Environmental Sciences/MOE Key Laboratory of Western China's Environmental System, Lanzhou University, Lanzhou 730000, China
  • Received:2018-03-28 Revised:2018-05-02 Published:2019-04-11

摘要: 干旱区风沙活动对全球环境和区域人类活动都可能造成巨大的影响。位于亚洲内陆的塔里木盆地是全球风沙活动最强烈的地区之一,然而该区域历史时期高分辨率的风沙活动记录比较缺少。博斯腾湖作为中国最大的内陆淡水湖,东南角湖区三面为沙丘包围,远离河流影响,可获得该区域的风沙活动记录。以博斯腾湖东南角钻取的长2.07 m沉积岩芯(BH08B)为研究对象,基于AMS 14C年代学框架,利用粒级-标准偏差模型和端元分析模型,提取钻孔沉积物中对环境变化敏感的粒度组分。结果表明:粒径变化的敏感组分2(>19.35 μm)和端元分析的风成沙端元EM2+EM3含量具有很好的一致性,均能指示研究区近2 000 a的风沙活动历史。重建结果表明:280-410 AD和1320-1800 AD两个时段风沙活动最强,410-1320 AD风沙活动最弱,而70-280 AD和1800 AD以来两个时段整体表现为较弱、低频率风沙活动。对比其他指示温度和湿度变化的古气候指标显示:风沙活动主要出现在冷期(如魏晋南北朝冷期和小冰期),气候变冷,西伯利亚高压强度增加,春季高压解体时风力增强,致使风沙活动频繁;干旱区风沙活动主要受温度控制,与干湿变化相关性不明显。值得注意的是,区域在280-410 AD的强风沙活动可能导致了楼兰古城的废弃。

关键词: 南疆, 博斯腾湖, 粒级-标准偏差, 端元分析, 风沙活动

Abstract: Eolian activity in arid areas can result in global-scale climate change as well as severely disrupt regional human activities. The Tarim Basin, located in the interior of Asia, is one of the regions with the strongest eolian activity in the world. However, high resolution records of late Quaternary eolian activity in this area are relatively scarce. Here we present the results of grain-size based regional eolian activity reconstructions from the Bosten Lake in the Yanqi Basin, Xinjiang, NW China. The sediment core, BH08B, was drilled in the southeastern part of Bosten Lake, which is surrounded by sand dunes and is isolated from fluvial influence. As two usually used methods of environment dynamics in arid area, the grain size-standard deviation curves and end-menmber models extracted grain-size sensitive component 2 (>19.35 μm) and end-member 2 and 3 were used to reconstruct the history of eolian activity over the past nearly 2 000 years. The grain-size sensitive component 2 (>19.35 μm) and end-member 2 and 3 extracted by grain size-standard deviation curves and end-member models should relate to eolian activities in this region, and the two proxies were used to reconstruct the history of eolian activity over the past nearly 2000 years. The results indicate the periods 280-410 AD and 1320-1800 AD were characterized by the most intense eolian activity. Conversely the period 410-1320 AD was characterized by the weakest eolian activity. However, 70-280 AD and since 1800 AD, eolian activity was also very low with few distinct accretionary episodes. On the basis of comparisons with independent climate records, phases of intense eolian activity mainly occurred during cold, dry climatic conditions, whilst weak eolian activity corresponded to relatively warm and humid climatic condition. The variable of temperature was found to provide highest explanation for intensity of eolian processes. Lower temperatures likely resulted in a strengthening of the Siberian High (SH) and then strengthen the ground wind when SH breaking out in spring accordingly. It is worth noting that the stronger eolian activity during 280-410 AD recorded in the Bosten Lake may have led to the abandonment of the ancient city of Loulan on the northern side of the Tarim Basin.

Key words: Southern Xinjiang, Bosten Lake, grain size-standard deviation, end-member analysis, eolian activity