黄河三角洲高分辨沉积记录及其对河道变迁和重大人类活动的响应

发布时间：2018-10-18 08:33

【摘要】：黄河中下游以淤积和善迁徙为特点，自1855年黄河入海位置由黄海改为渤海以来，尾闾进行了十余次大的改道。除此之外，为抗洪防涝等，还进行了修堤建坝、人工改道、调水调沙等一系列人类活动。而作为黄河在入海口的沉积体，黄河三角洲能够最为敏感的反应黄河流域环境的变化，并对此留下记录。因此，建立黄河三角洲高分辨沉积记录，并研究其对河道变迁和重大人类活动的响应，对于黄河流域的规划治理、黄河三角洲的油气资源开发与国土整治等具有十分重要的现实意义。本文基于取自黄河三角洲的六根短岩芯和一根长岩芯的粒度、灰度、地球化学以及放射性同位素特征进行了详细的研究，建立了黄河三角洲高分辨沉积记录，并研究了岩芯中河道变迁与调水调沙的沉积记录，研究表明：本研究区沉积物均以粘土质粉砂为主，砂含量最少，粉砂最多；频率分布曲线表现为单峰、双峰、或三峰，分别对应于不同的沉积环境；平均粒径多在6.5Φ~7Φ之间；岩芯的灰度值与粒度呈正相关，沉积物的X光图像可以反映出沉积物的粒度变化以及生物扰动情况，对于建立高分辨沉积记录有十分重要的作用。在六根短岩芯中，Si和Na元素之间一般具有正相关性，且与粒度呈现出明显的正相关，Al，Fe，Mg，Mn，K，Cu，Ni，Pb，，Zn等元素之间也一般具有较好的相关性，并与粒度呈现出明显的负相关；P、S、Cl等元素之间相关性较好，但它们与粒度的相关性很弱。但在B45中，所有元素与粒度之间的相关性都很差。通过对B45沉积物中常微量元素进行R型因子旋转分析，结果表明，沉积物中常微量元素主要受粒度、人类活动、生物组分和沉积物中残存盐分等的影响。岩芯沉积物粒度组成和210-Pb曲线是判断河道变迁的有效指标。黄河入海口的变动导致该处沉积物岩芯中210Pb曲线复杂化，以河流进积作用为主的情况下，呈现随深度逐渐衰变的特征；而在沉积物再悬浮沉积区，210Pb活度的分布往往会出现混合或倒置。黄河入海口变化导致沉积物粒度组成的相应改变。在河口入海处，三角洲以进积作用为主导，形成了细粒—单峰—正偏—分选好粒度类型(类型I)，反映了三角洲亚环境的特征；当黄河入海口改变时，原来的三角洲沉积区进入侵蚀、改造时期，波浪作用占主导地位，形成了相对粗粒—双峰—正偏—分选差的粒度类型(类型II)。黄河口近岸短岩芯记录记录了1976年、1996年两次黄河入海口的变迁，其中A11（于12.0cm处）、A19(于14cm处)沉积特征的突变记录了1996年黄河从清水沟改道清8汊入海的改道过程，A25(15.5cm处)岩芯则记录了1976年从刁口流路改道清水沟入海的改道过程。1855年黄河北归的事件在距离河口较远处的B45岩芯（于190cm处）得到了较好的记录，导致沉积物粒度的明显改变，并与测年结果相吻合。黄河调水调沙重大人类活动在河口沉积岩芯中亦有体现，导致沉积物粒度组成和元素组成的改变，见于A11岩芯2~4cm处以及A18岩芯中1.0~2.5cm处。
[Abstract]:With siltation and good migration in the middle and lower reaches of the Yellow River, the Yellow Sea has been changed from Yellow Sea to Bohai Sea since 1855. Besides, a series of human activities such as dam construction dam, artificial diversions, water diversion and sediment regulation are also carried out for flood prevention and waterlogging prevention and the like. As the sediment body of the Yellow River in the estuary, the Yellow River Delta can respond to the change of the environment of the Yellow River basin most sensitively, and record it. Therefore, it is of great practical significance to establish the high-resolution sedimentary records of the Yellow River Delta and study its response to river course changes and major human activities, and have very important practical significance for the planning and control of the Yellow River basin, the exploitation of oil and gas resources in the Yellow River Delta and the regulation of land and land. Based on the grain size, gray scale, geochemistry and radioactive isotope characteristics of six short-rock cores and a long rock core taken from the Yellow River Delta, this paper has established the high-resolution deposition of the Yellow River Delta. The sedimentary records of river course changes and sediment regulation sand in rock core were studied and studied. It is shown that the sediment in this study area is mainly argillaceous silt, with the minimum sand content and the most silty sand. The frequency distribution curve shows single peak, double peak, or three peaks, which correspond to different ones. The sedimentary environment of sediment and the average particle size are between 6. 5 and 7 Mt. The gray value of the rock core is positively correlated with the granularity, the Xlight image of the deposit can reflect the change of particle size and the biological disturbance, and it is very important to establish the high-resolution deposition record. It is important to have a positive correlation between Si and Na elements in six short-rock cores, and have obvious positive correlation with particle size. Al, Fe, Mg, Mn, K, Cu, Ni, Pb, Zn and other elements generally have good correlation, and have a good correlation with particle size. The correlation between P, S, Cl and other elements is good, but they are related to The correlation of particle size is weak. However, in B45, all elements and particle sizes The results show that trace elements in sediments are mainly affected by particle size, human activities, biological components and sediments. The influence of residual salinity, etc. The particle size composition and 210-Pb curve of the core sediments are The effective index of river course change is judged. The change of the estuary of the Yellow River causes the 210Pb curve in the sediment core of the sediment to be complicated, and the characteristic of gradual decay with depth is presented in the case of river inflow and accumulation, and the activity of 210Pb in the sediment re-suspension deposit area. The cloth tends to be mixed or inverted. The change in the inlet of the Yellow River causes the sink to sink The corresponding change of the particle size composition of the product is that in the estuary, the delta is dominated by the progradation effect, and the grain size type (type I) is sorted by the single-peak and positive skewer of the fine particle, which reflects the characteristics of the sub-environment of the delta; when the Yellow River is changed into the sea, the original delta is sunk. In the area of erosion and transformation, the wave plays an important role in the area of erosion, and the separation difference between the two peaks and the positive skewness of the relatively coarse grain is formed. Grain size type (type II) of the Yellow River estuary was recorded in 1976 and 1996, in which A11 (at 12. 0cm), A19 (at 14cm) sedimentary characteristics recorded the Yellow River from Qing Dynasty in 1996. The diversion process of the ditch diverges into the sea in August, and the core of A25 (15. 5cm) records the diversion process from the diversion channel to the sea in 1976. In 1855, the events of the north of the Yellow River were recorded at B45 rock core (190cm) at the distance from the mouth of the estuary, which resulted in the particle size of the sediment. The major human activities of the Yellow River diversion and adjustment are also reflected in the sediment cores of estuaries, resulting in the change of particle size composition and composition of the sediment, which is found at 2 ~ 4cm of A11 rock core and A1.
【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】：TV147;P343.5

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