福建漳浦海岸沙丘的沉积构造、粒度特征与沉积环境研究

发布时间：2018-06-18 10:56

本文选题：海岸沙丘 + 探地雷达　；参考：《福建师范大学》2015年硕士论文

【摘要】：福建东南沿海是我国海岸沙丘的主要分布区之一。本文以福建漳浦古雷半岛、六鳌半岛龙美、赤湖等地的海岸沙丘为研究对象,在野外剖面露头观测的基础上,采用探地雷达(GPR)对上述三个地点的海岸沙丘进行探测,分析了海岸沙丘沉积构造特点；对典型海岸沙丘剖面进行粒度采样,通过粒度组成、频率曲线和概率累积曲线、粒度参数分析,研究了海岸沙丘的粒度特征。在此基础上,综合分析研究区海岸沙丘的沉积构造和粒度特征,并对比前人研究成果,探讨研究区海岸沙丘的沉积相与沉积环境。本文得到以下初步认识：(1)运用探地雷达(GPR)探测海岸沙丘沉积构造结果表明,赤湖(CH)海岸沙丘以不连续的水平或亚水平层理为主,显示了低缓起伏的海岸横向沙垄或海岸沙席沉积构造特征。此外,在与盛行东北(NE)风垂直的雷达剖面上存在一个明显的宽度达15m以上的槽状界面,表明风沙沉积过程中曾遭受侵蚀作用；接近地面的雷达波较混乱,可能是受到植物根系或人类活动扰动产生的。龙美(LM)海岸沙丘,在平行于盛行东北(NE)风的剖面上主要发育向下风向倾斜的小角度倾斜层理,而垂直于盛行风方向的剖面为明显的连续水平层理,也存在楔形交错层理,显示了抛物线沙丘的沉积构造特点。同时,反映了研究区主要以NE方向的风力作用为主,偶尔出现较弱的SW向风力交替的情况；古雷(GL)海岸沙丘以中等连续／不连续的水平/亚水平层理为主,在平行于盛行东北(NE)风方向的靠陆一侧发育向SW方向倾斜的前积层,显示抛物线沙丘和横向沙垄的沉积构造特点。通过对研究区三个海岸沙丘探地雷达图像的解译,可以归纳为5种沙丘沉积构造的雷达相。研究发现,不同沙丘类型或同一沙丘类型的不同部位,沉积构造雷达相存在一定差异。(2)研究区海岸沙丘粒度分析结果表明,相较于中国温带和华南其他地区的海岸沙丘,福建漳浦海岸沙丘的粒度组成明显偏粗,分选性偏差、较多负偏态、峰态中等。沿着研究区盛行的东北(NE)风方向,三个地点海岸沙丘的粒度逐渐变粗,即CHLMGL。在剖面垂直方向上,三个海岸沙丘自下而上,沙丘砂的平均粒径都有逐渐变细的趋势。综合频率曲线、概率累积曲线和C-M图分析,大部分海岸沙丘下部以波浪作用和风暴潮沉积为主,搬运动力较强；上部则以风力作用为主,搬运动力有所减弱。(3)综合海岸沙丘沉积构造和粒度特征反映的沉积环境：赤湖(CH)海岸沙丘属于滨海沙席或形态和缓的横向沙丘,其物源以海滩砂为主；龙美(LM)海岸沙丘和古雷(GL)海岸沙丘,是分别位于六鳌半岛和古雷半岛连岛沙坝上的抛物线沙丘和横向沙垄,滨海植物在这两个地点的海岸沙丘发育中具有重要作用。LM海岸沙丘和GL海岸沙丘的物源主要有两种,一是来自连岛沙坝上粗砂物质的近源沉积,组成颗粒较粗的组分,且主要分布在沙丘下部；二是台风或风暴潮向陆搬运沉积下来的海滩砂,主要分布在沙丘上部。(4)在粒度分析方法方面,针对研究区海岸沙丘粒度组成较粗的实际,本文采用了筛分法和激光衍射法进行粒度分析对比。结果表明,由于筛分法和激光衍射法的测试原理不同,得到的结果也存在一定差异,但粒度组成的总体分布趋势一致；概率累积曲线显示,筛分法和激光衍射法对中等颗粒测试结果的一致性最好；在沉积物粒度测试中,筛分法比较适合粗颗粒沉积物粒径的测量,而激光衍射法则更适用于细颗粒沉积物的粒度分析。
[Abstract]:The southeast coast of Fujian is one of the main distribution areas of the coastal dunes in China. In this paper, the coastal sand dunes in Zhangpu Gure Peninsula, the six top Peninsula, the dragon and the US and the Chek lake are studied. On the basis of the outcrop observation in the field, the ground penetrating radar (GPR) is used to detect the coastal dunes of the above three ground points and to analyze the deposition of the coastal dunes. The grain size of typical coastal dunes is sampled, the granularity characteristics of coastal dunes are studied through grain size composition, frequency curve and probability accumulation curve and grain size parameter analysis. On this basis, the sedimentary structure and grain size characteristics of coastal dunes in the study area are synthetically analyzed, and the study area coast is compared with the previous research results. The sedimentary facies and sedimentary environment of sand dunes. This paper obtains the following preliminary understanding: (1) using ground penetrating radar (GPR) to detect the sedimentary structure of coastal dunes shows that the sandy dunes in Chek Lake (CH) coastal dunes are dominated by discontinuous horizontal or subhorizontal bedding, showing low undulating coastal horizontal sand ridges or coastal sand mat depositional structures. In addition, it is in vogue. The vertical radar profile of the Northeast (NE) has a significant trough - like interface over the width of more than 15m, indicating that the wind sand deposits have been eroded during the sediment deposition; the radar waves near the ground are more chaotic and may be caused by plant roots or disturbance of human activity. The LM coast dunes are parallel to the prevailing northeastern (NE) wind profiles. There is a small angle inclined bedding in which the downward wind direction is mainly developed, while the section perpendicular to the direction of the wind is a clear continuous horizontal bedding, and there is a wedge cross bedding. It shows the characteristics of the sedimentary structure of the parabolic sand dunes. At the same time, it is reflected that the main wind force in the NE direction is mainly in the study area, and the weak SW to the wind direction occasionally occurs. The Gure (GL) coastal dunes are dominated by a medium continuous / discontinuous horizontal / subhorizontal bedding, which develops into the front of the SW direction in the leaning side parallel to the prevailing Northeast (NE) wind direction, showing the sedimentary structure of the parabolic dunes and lateral ridges. Through the GPR images of three coastal dunes in the study area The interpretation can be summed up as the radar facies of 5 kinds of sand dune sedimentary structures. It is found that there are certain differences in the sedimentary structure radar phase of different sand dune types or the same sand dune types. (2) the result of the grain size analysis of the coastal dunes in the study area shows that compared to the coastal dunes in the temperate zone of China and the other areas of Southern China, the sand dunes in the Zhangpu coast of Fujian. In the direction of the Northeast (NE) wind, the grain size of the coastal sand dunes in the three locations gradually becomes coarser along the direction of the Northeast (NE) wind in the study area. That is, the CHLMGL. is in the vertical direction of the section, and the average grain size of the sand dunes is gradually thinning, and the average particle size of the sand dunes is gradually thinning. The comprehensive frequency curve is the trend of the grain size of the sand dunes. The probability accumulation curve and C-M map analysis show that most of the coastal dunes are dominated by wave action and storm tide deposit, and the moving power is stronger. The upper part is mainly wind force, and the moving power is weakened. (3) the sedimentary structure and grain size characteristics of the comprehensive coastal dunes are reflected by the sedimentary structure and grain size characteristics of the coastal dunes: the CH beach dunes belong to the seashore mat or form. A gentle horizontal sand dune is the main source of beach sand; LM coast sand dunes and Gure (GL) beach dunes are parabolic dunes and lateral ridges on the six top Peninsula and Gure Peninsula, respectively. The coastal dunes play an important role in the coastal dunes and the GL coastal dunes in the development of the coastal dunes in these two locations. There are two main sources, one is the near source deposit of coarse sand material from the sand dam on the island of Lian Island, which is composed of coarser components and mainly distributed in the lower part of the sand dunes. Two is the beach sand deposited by typhoon or storm tide, mainly in the upper sand dunes. (4) the particle size composition of the coastal dunes in the study area is in the size segregation method. The size analysis and comparison between the screening method and the laser diffraction method are used in this paper. The results show that the results of the screening method and the laser diffraction method are different, but the overall distribution trend of the particle size is the same, the probability accumulation curve shows that the sieving method and the laser diffraction method are of medium size. The consistency of the grain test results is the best. In the grain size test, the sieving method is suitable for the measurement of the particle size of the coarse grain sediments, and the laser diffraction rule is more suitable for the particle size analysis of the fine grain sediments.
【学位授予单位】：福建师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P737.1

【参考文献】