盘锦海岸沙丘发育过程与环境指示意义

发布时间：2018-05-08 12:47

本文选题：海岸沙丘 + 光释光测年　；参考：《中国地质大学（北京）》2014年硕士论文

【摘要】：海岸沙丘在我国分布及其广泛，而海岸沙丘沉积是记录海岸带环境演变的良好信息载体，因此可以作为揭示古环境演变途径的一个重要补充。本文选择辽宁盘锦海岸沙丘为研究对象，采用野外考察、典型剖面选取懫样、室内实验分析、区域对比和综合分析的方法开展研究工作。通过对盘锦海岸沙丘的光释光测年和沙丘粒度特征的分析，确定了沙丘的发育年代；并结合盘锦地区地形地貌、气候水文等方面的资料分析盘锦沙丘的成因；在统一的时间标尺上，综合对比东亚季风变化序列、近千年来区域降水量和温度变化记录探讨了沙丘形成的控制因素和环境意义。通过以上分析得出以下结论：（1）粒度分析结果显示，盘锦海岸沙丘砂由中、细砂组成，以细砂为主，分选中等，粒度频率曲线普遍为单峰加一细尾，峰态较窄。与典型海岸沙丘相比，沉积物粒径偏细，频率曲线细尾更为明显，造成这种差异可能是由风沙沉积后，遭受后期的风化作用造成的。整体上来看，，盘锦海岸沙丘的粒度组成与国内其他地区的海岸沙丘组成相类似，表现出了典型海岸风成沙丘的特征。（2）通过对盘锦海岸沙丘剖面3现场观察，结合剖面粒度特征的分析得出，盘锦沙丘剖面3以0.2m为界，0.2m以上部分为风成沙丘，0.2m以下部分为灰黑色砂质粘土，风成沙丘和灰黑色古土壤沉积特征的差异，指示了剖面沉积环境的变化，并确定了沙丘的底界。（3）通过对盘锦沙丘的OSL测年，确定了沙丘的发育于近800年以来，并通过与东亚季风和千年降水量和温度记录等因素，综合对比分析得出影响盘锦沙丘形成的主要因素为干冷的气候条件。（4）形成沙丘的有利条件：大凌河、辽河等河流携带大量泥沙入海为沙丘发育提供了充足的物质来源，春季持久干燥的西南向岸风为沙丘的发育提供的动力条件，盘锦地区平坦宽广的地形条件有利于海滩沉积物向岸搬运而形成海岸沙丘。
[Abstract]:Coastal dune is widely distributed in China, and coastal dune deposition is a good information carrier to record the evolution of coastal zone environment, so it can be used as an important supplement to reveal the path of paleoenvironmental evolution. In this paper, the sand dune in Panjin coast of Liaoning Province is chosen as the research object. The methods of field investigation, typical section selection, laboratory experimental analysis, regional contrast and comprehensive analysis are used to carry out the research work. Based on the analysis of photoluminescence dating and grain size characteristics of panjin sand dune, the development age of sand dune is determined, and the origin of panjin sand dune is analyzed with the data of topography, geomorphology, climate and hydrology, etc. Based on a unified time scale and a comprehensive comparison of the East Asian monsoon variation series, the controlling factors and environmental significance of sand dune formation are discussed in the recent millennia of regional precipitation and temperature change records. Through the above analysis, the following conclusions are drawn: The results of grain size analysis show that the sand of Panjin coast dune is composed of medium and fine sand, mainly fine sand and medium sorting. The particle size frequency curve is generally single peak with a fine tail, and the peak state is narrow. Compared with the typical coastal dunes, the grain size of the sediment is smaller and the finer tail of the frequency curve is more obvious, which may be caused by the late weathering of the aeolian sand deposit. On the whole, the granularity composition of Panjin coastal dune is similar to that of other coastal dunes in China, showing the typical coastal eolian sand dunes. (2) based on the field observation of Panjin coastal dune profile 3 and the analysis of the grain size characteristics of the section, it is concluded that Panjin dune section 3 is gray-black sandy clay with a boundary of 0.2m or more than 0.2m of wind-formed sand dunes and less than 0.2m. The difference between eolian sand dunes and gray-black paleosols indicates the change of sedimentary environment in the profile and determines the bottom boundary of sand dunes. The OSL dating of Panjin dune shows that the sand dune has developed in the past 800 years, and has been associated with the East Asian Monsoon and the Millennium precipitation and temperature record, etc. The main factors affecting the formation of Panjin sand dunes are dry and cold climatic conditions. 4) favorable conditions for sand dune formation: Daling River, Liaohe River and other rivers carry a large amount of sediment into the sea to provide sufficient material sources for the development of sand dunes, and the long-lasting dry southwest coastal wind in spring provides the power for the development of sand dunes. The flat and broad terrain conditions in Panjin area are favorable for beach sediment to be transported to shore to form coastal sand dunes.
【学位授予单位】：中国地质大学（北京）
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P737.1

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