渤海中南部沉积地球化学特征和黄河改道事件

发布时间：2018-01-12 05:01

本文关键词：渤海中南部沉积地球化学特征和黄河改道事件　出处：《中国海洋大学》2014年硕士论文　论文类型：学位论文

【摘要】：渤海是三面被陆地环绕的半封闭陆表海，其沉积作用受到以黄河为代表的周边河流的强烈影响。历史上，黄河曾经游荡于黄海、渤海之间，每次改道对渤海而言都是一次重大的沉积事件，深刻改变渤海沉积过程。基于表层沉积物和沉积物岩芯的地球化学研究，从现代沉积状态反演历史时期的沉积演变，可为深入了解渤海沉积物源汇作用提供科学支持。本研究通过对渤海表层及柱状沉积物中粒度、常量元素和微量元素含量组合及变化特征的系统分析，探讨了表层沉积物的空间分布及其影响因素，揭示了1855年黄河改道事件的沉积学记录，阐明黄河改道前后渤海沉积环境效应。主要得到以下研究成果：渤海中南部表层沉积物的粒度特征总体表现为研究区中、南部较细，东北部和西北部较粗，分别对应黄河物质、辽东浅滩和滦河沉积物的特征。表层沉积物中的常量元素Si和Na的空间分布呈现出北高南低的相似特点；Al、Fe等5种元素的空间分布特征类似；Ca的分布与上述元素组合均有所差异。表层沉积物中的V、Cu等5微量元素在空间分布上具有相似的趋势；Sr、Zr和Ba元素则各自有自己分布上的特点。依据主量元素和微量元素组成，研究区可以清晰地分成四个分区：一区和二区都以低含量的Si、Sr、Ba和Zr，高含量的Al、Ca以及V、Cu等微量元素为特征，总体上均以黄河来源的物质为主，但在莱州湾沿岸冲刷物及水动力环境的影响下有所差异；三区主要以异常高含量的Mn、P及较高含量的Sr、Ba和Zr为特征，体现了辽东浅滩水动力强劲、明显偏氧化的的沉积环境特点；四区以高Si、低Al以及微量元素含量都较低为特征，代表了滦河来源为主的沉积物。渤海中部沉积物岩心的粒度、地球化学组成上可以明显地分成两段，上段粒度特征以平均粒径细、分选好及单峰形态、元素含量方面以高Ni、Zn及低Mn、Sr、Ba和Zr为特征，下段粒度特征以平均粒径粗、分选差及双峰形态、元素含量方面以低Ni、Zn及高Mn、Sr、Ba和Zr为特征。这种差异是由于1855年黄河改道所致。黄河改道入海渤海使得渤海中部沉积物来源、沉积动力环境发生明显的改变，改道前为滨—浅海沉积环境，，沉积物来源复杂，波浪作用强，属于氧化环境，有利于底栖生物发育；改道后为前三角洲、三角洲前缘环境，沉积物来源单一，三角洲的进积作用占主导，偏向还原环境，底栖生物不发育。
[Abstract]:Bohai is a semi enclosed sea surface on three sides surrounded by land, the strong influence of deposition is represented by the Yellow River river. Historically, the Yellow River has been wandering in the Yellow Sea, Bohai, each diversion is a major depositional event for Bohai, profound change Bohai geochemical deposition process. Study on surface sediments and sediment cores based on sedimentary evolution from modern sedimentary state inversion period, can provide scientific support for the in-depth understanding of Bohai sediment source sink.
Based on the size of Bohai and surface sediments, analysis of major and trace elements content combination and change characteristic, discusses the spatial distribution and influencing factors of surface sediments, reveals the sedimentary records of 1855 the Yellow River diversion events, clarify the diversion of the Yellow River before and after the Bohai sedimentary environment effects. The following are the main research results:
The grain size characteristics of the overall performance of the surface sediments from the central and southern Bohai as the study area, the south is fine, northeast and northwest are thick, corresponding the Yellow River material, characteristics of the Liaodong shoal and the Luanhe River sediments.
The major elements in the surface sediments of Si and the spatial distribution of Na showed similar characteristics of North High South low; Al, the spatial distribution characteristics of 5 kinds of elements such as Fe Ca and the like; the distribution of elements in the surface sediments are different. V, Cu and other 5 trace elements have the similar trend in spatial distribution on Sr, Zr and Ba; the element of their respective characteristics of the distribution.
On the basis of major elements and trace elements, the study area can be clearly divided into four zones: a region and a two region with low content of Si, Sr, Ba and Zr, the high content of Al, Ca and V, for the characteristics of trace elements such as Cu, on the whole are in the Yellow River source material, but the difference in the effect of scouring and the Gulf of Laizhou coast hydrodynamic environment; three areas mainly in the abnormally high content of Mn, P and high content of Sr, Ba and Zr characteristics, reflects the Liaodong shoal water power strong, obviously oxidation characteristics of sedimentary environment; four areas with high Si and low Al and the contents of trace elements are lower as the characteristic, represents the main source of the Luanhe River sediments.
The size of central Bohai sediment cores, geochemical composition can be clearly divided into two sections, with the average grain size characteristics of the upper fine particle size, good sorting and single peak pattern, with high content of Ni, Zn and low Mn, Sr, Ba and Zr characteristics, grain size characteristics of lower segment with average particle diameter, sorting and the Shuangfeng morphology, element content in low Zn and high Ni, Mn, Sr, Ba and Zr. The characteristic of this difference is due to the diversion of the Yellow River in 1855.
The Yellow River, the center of Bohai Bohai sea sediment sources, sediment environment changed before diversion to shore neritic sedimentary environment, sedimentary source complex, strong wave action, which belongs to the oxidizing environment conducive to benthic development; after the diversion for predelta, delta front, delta sediment source is limited. Progradation dominates, bias reduction environment and benthic organisms are not developed.

【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P343.1;P736.4

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