黄河上游戈龙布滑坡及其堰塞湖沉积物光释光年代研究

发布时间：2018-03-31 00:02

本文选题：巨型滑坡　切入点：堵江　出处：《南京师范大学》2015年硕士论文

【摘要】：黄河上游戈龙布巨型古滑坡(50.4×106m3)位于积石峡水电站库区,具有重要的工程地质意义；同时戈龙布滑坡堰塞湖溃决对下游地区的官亭盆地喇家文化的古环境产生了重大的影响,而具有重要的史前灾害意义。近年来该滑坡成为一个热点的研究对象,已有的研究从工程地质学的角度对该滑坡进行了系统的研究,但是有关该滑坡和滑坡堰塞湖的形成年代却一直存在争议：最初的研究认为其形成于8,000-9,000 a BP；而后来的多数研究根据14C年代和光释光(OSL)测年结果推断该滑坡堰塞湖形成于约7,000-9,000 a BP；有研究者认为其形成年代达到了10,000 a BP；也有研究认为该滑坡堰塞湖及其溃决洪水发生于大约3,700 a BP。湖相沉积物作为第四纪环境测年的物质被大量应用,常用的14C测年法因其测年范围较窄、适合测年的物质获取不能保证以及易受老碳影响,使其应用到湖相沉积物测年中受到了一定限制。OSL测年技术的发展为湖相沉积物测年提供另一有效手段,国内外大量研究也对湖相沉积物在OSL测年中的适用性进行了探讨,且获得较多可靠的年代结果。但OSL测年法在湖相沉积物中的应用目前还存在一些问题制约其发展,主要包括OSL样品是否完全晒退以及含水量对环境剂量率的影响等方面。为了进一步确定戈龙布古滑坡和滑坡堰塞湖的形成年代,本文以戈龙布古滑坡堆积体上滑坡塘和小型堰塞湖的湖相沉积物,以及戈龙布滑坡堵塞黄河干流形成堰塞湖的湖相沉积物为测年材料,采集OSL样品,在南京师范大学地理科学学院释光实验室Lexsyg释光仪器完成等效剂量测量。在OSL年代分析与研究中,对比De值分布图以及测试不同粒径的样品来检测样品的晒退程度；计算样品的饱和含水量以及实测含水量,同时考虑样品在堰塞湖生命周期不同阶段的含水量。根据实验结果取得以下研究成果：(1)通过戈龙布滑坡堆积体上滑坡塘和滑坡堰塞湖的湖相沉积物中同一样品的细颗粒(4-11μm)和中颗粒(38-63μm)的De值和OSL年代结果的对比,揭示了大部分样品的中颗粒的De值比细颗粒小且OSL年代较为年轻。说明这两类滑坡相关的湖相沉积物中,中颗粒的晒退情况比细颗粒好,因此滑坡相关的湖相沉积物的OSL测年选择中颗粒组分更为适合。(2)通过使用两种不同的含水量计算方法得到的OSL年代结果相差较大,揭示了戈龙布滑坡堰塞湖存在期间,湖相沉积中的水分含量对等效剂量的累积具有明显的影响,最终影响年代的准确估计。考虑堰塞湖生命周期的含水量变化后,得到的OSL年代大小增加了5%-17%。(3)由于戈龙布滑坡相关湖相沉积物的来源以及搬运方式、距离等不同,得到了OSL年代结果跨度较大。戈龙布古滑坡堆积体上滑坡塘的OSL测年材料应选择较粗的颗粒；黄河干流戈龙布滑坡堰塞湖的湖相沉积物经过了长距离的搬运、晒退程度较好,适合OSL测年。(4)通过对戈龙布滑坡相关湖相沉积物OSL年代测试和综合分析表明,戈龙布古滑坡堆积体上的滑坡塘形成的OSL年代不早于7.55±0.53 ka；戈龙布滑坡堵塞黄河干流形成堰塞湖的湖相沉积物底部的XTC-4和YS-2样品OSL年代分别为7.64±0.68 ka、7.52±0.17 ka。由滑坡塘和黄河干流堰塞湖的湖相沉积的年代结果可以推断,戈龙布滑坡发生的年代在7,000-8,000 a BP之间。
[Abstract]:The giant paleolandslide ( 50.4 脳 106m3 ) upstream of the upper reaches of the Yellow River is located in the reservoir area of Jishixia Hydropower Station , which has important engineering geological significance ;
In recent years , the landslide has become a hot spot in the study of the landslide , but there has been a dispute about the formation of the landslide and landslide dammed lake : the initial study found that it was formed in 8,000 - 9,000 a BP ;
Most of the studies later concluded that the landslide dammed lake was formed at about 7,000 to 9,000 a BP based on the results of the 14C dating and OSL dating .
The researchers thought that it had reached 10,000 a BP in the 1980s ;
The application of OSL dating technique in lake facies sediments has restricted its development . However , the application of OSL dating technique in lake facies sediments has restricted its development , mainly including whether the OSL sample is fully exposed and the influence of water content on environmental dose rate .
The results are as follows : ( 1 ) Compared with the results of OSL ' s , the results are as follows : ( 1 ) Compared with the results of OSL ' s , the results are as follows : ( 1 ) The results of OSL dating of the same sample in the lake facies sediments of the landslide pond and the landslide dammed lake are more suitable than those in the OSL dating . ( 2 ) The OSL dating results of the landslide - related lake facies sediments increased by 5 % -17 % .
( 4 ) The OSL age of the landslide pond on the Gulong Bugu landslide is not earlier than 7.55 卤 0.53 ka .
The levels of XTC - 4 and YS - 2 were 7.64 卤 0.68 ka and 7.52 卤 0.17 ka at the bottom of the lake facies sediments in the mainstream of the Yellow River , and the age of the landslide occurred between 7,000 and 8,000 a BP .

【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.22;P597.3

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