晚更新世以来黄河三角洲的沉积相划分及环境演化研究

发布时间：2018-01-23 18:25

本文关键词： 黄河三角洲晚更新世沉积相环境演化　出处：《中国海洋大学》2014年硕士论文　论文类型：学位论文

【摘要】：三角洲位于海陆交互地带，对气候、海平面波动等变化较为敏感。大量第四纪沉积学研究表明,沉积记录中保存着其形成时期的气候和环境信息。对黄河三角洲沉积相和沉积环境的判别和信息提取，是理解三角洲沉积演化过程的重要前提，揭示了三角洲演化过程对环境变化的响应，同时为三角洲地区的开发利用以及区域可持续发展提供科学依据。本文依托项目《我国典型海岸带系统对气候变化的响应机制及脆弱性评估研究》子课题《气候变化影响下典型海岸冲淤过程及演变趋势》，选取位于现行黄河流路与1996年以前现行黄河故道之间潮间带的QSG孔为重点研究对象，利用岩性描述、粒度分析、体积磁化率分析、元素地球化学特征分析、有孔虫分析以及AMS14C测年等综合分析，对QSG孔进行了沉积相划分，从中识别出河湖相、潮坪及滨岸沼泽相、浅海相、现代黄河三角洲沉积相，并结合三角洲地区其他钻孔资料综合分析黄河三角洲地区的环境演化过程，为黄河三角洲的环境演化补充了资料。晚更新世以来黄河三角洲地区QSG孔位置可划分为从上至下六个沉积相：第一沉积相：1.8-3.3m三角洲平原相；第二沉积相：3.3-8.92m三角洲前缘相；第三沉积相：8.92-17.92m前三角洲相；第四沉积相：17.92-20.49m浅海相；第五沉积相：20.49-24.22m潮坪及沼泽相；第六沉积相：24.22-32.10m河湖相。本区环境演化分为四个阶段：第一阶段（24.22-32.10m）：反映了末次盛冰期末期低海面时期，海平面达到最低，本区发育河流和湖泊沉积。随后，气温升高，海平面上升，在全新世海侵刚开始时，本区的河流和湖泊作用仍然为主要作用，为干旱的氧化环境。第二阶段（20.49-24.22m）：本阶段为冰后期海侵沉积，全新世海侵过程开始，海平面上升，海水逐渐侵入滨海平原地区，本区发育潮坪和滨岸沼泽沉积，沉积环境复杂。第三阶段（17.92m-20.49m）：为高海面时期，距今7000年左右，随着海面的持续上升，该地区逐渐被海水淹没，呈浅海环境。距今约6000年海平面达到最高，且海平面上升速率下降，保持稳定。其间本区的海水水深加大，且同时还原程度增强，本区为陆架浅海环境。第四阶段（1.8-17.92m）：为高海面稳定时期，对应1855年以来形成的现代黄河三角洲沉积物，海平面基本保持稳定，黄河改道后带来大量泥沙在河口外堆积，形成水下三角洲，先后发育前三角洲沉积，三角洲前缘沉积，黄河三角洲平原沉积环境，显示为氧化—还原环境交替。研究结果表明晚更新世晚期以来黄河三角洲的环境演化对海平面的变化有所响应。结合本区已有的钻孔研究结果，基本形成了黄河三角洲由陆向海发育演化的连续系列，，为研究该区域海平面变化和环境演化提供了重要的参考。
[Abstract]:The delta is located in the sea and land interaction zone and is sensitive to the changes of climate and sea level fluctuation. A large number of Quaternary sedimentology studies show that. The climatic and environmental information of the formation period is preserved in the sedimentary records. The identification and extraction of the sedimentary facies and sedimentary environment of the Yellow River Delta is an important prerequisite for understanding the evolution process of the delta sediments. It also reveals the response of delta evolution to environmental change and provides scientific basis for the development and utilization of delta and regional sustainable development. This paper relies on the project "response Mechanism and vulnerability Assessment of typical Coastal Zone system to Climate change in China" sub-topic "scour and deposition process and evolution trend of typical coastal zone under the influence of climate change". The QSG hole in the intertidal zone between the current Yellow River flow road and the existing Yellow River old road before 1996 is selected as the key research object, and the lithologic description, particle size analysis and volumetric susceptibility analysis are used. Element geochemical characteristics, foraminifera analysis and AMS14C dating were used to classify the sedimentary facies of the QSG pore, from which the river and lake facies, tidal flat and shoreline marsh facies and shallow marine facies were identified. The sedimentary facies of the modern Yellow River Delta, combined with other borehole data in the delta area, comprehensively analyze the environmental evolution process in the Yellow River Delta region, which provides additional data for the environmental evolution of the Yellow River Delta region. Since the late Pleistocene, the QSG pore location in the Yellow River Delta can be divided into six sedimentary facies from the upper to the lower: the first sedimentary facies: the first sedimentary facies: 1. 8-3.3 m delta plain facies; The second sedimentary facies is the front facies of delta of 3.3-8.92m; The third sedimentary facies: the delta facies before 8.92-17.92m; 4th sedimentary facies: shallow sea facies: 17.92-20.49m; 5th sedimentary facies: 20.49-24.22m tidal flat and marsh facies; 6th sedimentary facies: 24.22-32.10m fluvial and lacustrine facies. The environmental evolution of this area is divided into four stages: The first stage (24.22-32.10 m) reflects the low sea level at the end of the last glacial maximum, the lowest sea level and the development of river and lake deposits in this area. Then, the temperature rises and the sea level rises. At the beginning of the Holocene transgression, the rivers and lakes in this area still play a major role in the arid oxidation environment. The second stage is 20. 49-24. 22mN: this stage is post-glacial transgression deposition. The transgression process began in Holocene, sea level rose and seawater gradually invaded coastal plain area. The tidal flat and shoreline marsh deposits are developed in this area, and the sedimentary environment is complex. The third stage is 17.92m-20.49m: it is a period of high sea level, about 7000, with the rising of sea surface, the area is gradually submerged by sea water. The sea level reached the highest in 6000, and the rising rate of sea level decreased steadily. Meanwhile, the depth of sea water in this area increased and the degree of reduction increased at the same time. This area is continental shelf shallow sea environment. Stage 4th is 1.8-17.92m: high sea level stabilization period, corresponding to the modern Yellow River delta sediments formed since 1855, the sea level is basically stable. After the diversion of the Yellow River, a large amount of sediment accumulates outside the estuary, forming the underwater delta, successively developing the pre-delta deposition, the delta front sedimentation, and the Yellow River delta plain sedimentary environment. Shown as an alternate oxidation-reduction environment. The results show that the environmental evolution of the Yellow River Delta since the late Pleistocene is responsive to the sea level change. A series of continuous evolution of the Yellow River Delta from the continental to the sea has been formed, which provides an important reference for the study of the sea level change and environmental evolution in the region.
【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】：P736.21;P343.5

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