历史时期黄河下游地区环境演变的湖泊沉积记录

发布时间：2018-05-20 00:31

本文选题：湖泊沉积 + 环境演化　；参考：《聊城大学》2015年硕士论文

【摘要】：黄河下游地区地处我国中北部,位于典型的东亚季风区,对气候变化的响应十分敏感。历史时期黄河下游的湖泽超过180个,不亚于今日长江流域湖泊之数量,但在全球气候变化的大背景下,由于受到黄河频繁改道变迁以及人类活动加剧的影响,绝大多数湖泽已经消亡。该区域的湖泊沉积物蕴含了丰富的环境演变和人类活动的信息,对于湖泊沉积物的研究,将对恢复该区域古环境,理解黄河改道变迁历史以及与人类活动的响应具有重要意义。论文以黄河下游地区古冷水沟短岩芯为研究对象,通过高精度的AMA-14C测年,结合粒度、TOC、C/N、元素等气候/环境代用指标测试分析,重建了2500年以来该区域的沉积环境历史,论文取得了以下研究结果:(1)基于精确的AMS-14C定年框架,结合粒度、WC、TOC等多指标分析表明:2500年以来冷水沟沉积环境大致可分为以下几个特征阶段:2500~1700 cal yr BP期间,为滨湖相或冲积平原相沉积环境;1700~1000 cal yr BP期间,为浅湖相沉积环境;1000 cal yr BP之后,转化为河流相或冲积平原相沉积环境。(2)基于以上沉积环境及建立的年代框架,利用多环境代用指标综合分析重建了近2500年以来冷水沟地区环境演变信息。结果表明:2500~1700cal yr BP,气候较为暖湿,后期转冷,且人类活动强度较低,湖泊受黄河改道影响频繁,沉积环境为洪泛平原相或浅湖相沉积;1700~1000cal yr BP,气候以暖湿为主,间或有极端干冷气候,且变化频繁,沉积环境为浅湖相静水沉积或相对稳定的湖滨相沉积;1000 cal yr BP演变为河流相或冲积平原相沉积,期间,人类活动影响逐渐增强,气候较为温暖,且呈现上升趋势,这一时段,湖泊为发育后期,有走向衰亡的趋势。(3)黄河下游地区环境演变的序列与北半球季风区石笋、极地和高原冰芯等记录的综合对比表明,区域气候环境变化既有同步性,也有各自的特定及演化特征。通过探究发现,本区域的环境变迁可能多受控于黄河改道以及地球系统内部相对复杂的海-陆-气耦合过程。
[Abstract]:The lower reaches of the Yellow River, located in the north of China, are located in the typical East Asian monsoon region, and are sensitive to the response to climate change. The lower reaches of the lower reaches of the Yellow River are more than 180 in the historical period, no less than the number of lakes in the Yangtze River Basin today, but in the context of global climate change, the frequent changes in the Yellow River and the intensification of human activities are due to the changes in the global climate. The lake sediments in the region contain abundant environmental evolution and information of human activities. The study of lake sediments will be of great significance to the restoration of the Paleoenvironment in the region, the understanding of the history of the change of the Yellow River's change and the response to human activities in the lower the Yellow River region. The short rock core of the gully is the research object. Through the high precision AMA-14C dating, combined with the test and analysis of the climatic / environmental substitution indexes, such as grain size, TOC, C/N, and elements, the sedimentary environment history of the region has been reconstructed since 2500. The following results have been obtained in this paper: (1) based on the precise AMS-14C annual framework, combined with the granularity, WC, TOC and other index analysis, it is shown that Since 2500, the sedimentary environment of chilled water gully can be divided into the following characteristic stages: during the period of 2500~1700 cal yr BP, the sedimentary environment for Binhu facies or alluvial plain facies; during 1700~1000 cal yr BP, it is shallow lacustrine sedimentary environment; after 1000 cal yr BP, it is converted into fluvial facies or alluvial plain facies sedimentary environment. (2) based on the above sedimentary environment and construction The environmental evolution information of cold water gully area since 2500 was reconstructed by the comprehensive analysis of multi environment substitution index. The results showed that the 2500~1700cal yr BP was warm and wet, later cooled, and the intensity of human activity was low. The lake was influenced frequently by the Yellow River transformation, and the sedimentary environment was flooded plain or shallow lacustrine facies; 1700~10 00cal yr BP, the climate is mainly warm and wet, and there is an extreme dry and cold climate with frequent changes. The sedimentary environment is shallow lacustrine hydrostatic deposit or relatively stable lakeside deposit; 1000 cal yr BP evolves into fluvial facies or alluvial plain facies. During the period, the influence of human activity gradually increases, the climate is warmer, and presents a rising trend, this period, this time period, The lake has a trend of decline and decline in the late development. (3) the sequence of environmental evolution in the lower reaches of the Yellow River and the records of the northern hemisphere monsoon area stalagmite, polar and plateau ice cores show that the regional climate and environment changes are both synchronous, and also have their own specific and evolutionary characteristics. It is controlled by the transformation of the Yellow River and the relatively complicated sea land atmosphere coupling process within the earth system.
【学位授予单位】：聊城大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P532;P512.2

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