【作者】 刘恩峰；

【导师】 张祖陆；

【作者基本信息】 山东师范大学 ， 自然地理学， 2002， 硕士

【摘要】 前人研究将咸水入侵区分为显性入侵和隐性入侵，隐性入侵系指在自然状态下，咸水向淡水区的扩散；显性入侵指由于人类活动的干预，引起咸水向淡水区快速的侵染。咸水入侵已成为莱州湾南岸平原典型的环境灾害，其发生不仅是现代环境变化的产物，而且也与古环境演化有着密切的联系。沉积环境变化是咸水入侵产生的背景因素，现代环境变化是咸水入侵产生的主导及驱动因素。本文通过分析莱州湾南岸潍河下游地区晚更新世以来的环境变化，从环境学和沉积学的角度研究了咸水入侵的成因及变化规律。 本次研究通过多次野外实地考察和验证，搜集了大量的地质钻孔资料。在莱州湾南岸潍河下游地区，选取咸水入侵典型剖面，钻取岩心样品，对沉积物进行了粒度分析，孢粉分析、微体古生物分析，¹⁴C及热释光测年，并对典型剖面（A—A’）的五个观测井进行了全年水化学监测，获取了详实的咸一淡水过渡区地下水变化规律的数据。 本文通过大量沉积学指标的分析，对潍河下游地区环境变化特征进行了系统的研究，恢复并建立了区域古环境沉积序列，与相邻区域进行了对比。研究发现，本区在全球环境变化的背景下，具有一些特有的变化过程与演化特征：第四纪时期一直受差异性沉降构造运动的控制，沉积物厚度在潍河下游地区最厚可达300m，沉积物主要以粗、中砂或粉砂为主：受第四纪冰期气候变化的影响，本平原区自晚更新世以来经历了三次海平面升降变化带来的海陆环境变迁，造成了潍河下游地区草甸草原与滨海一浅海沉积环境的交替变化；随着海岸线的进退，本区形成了巨厚的海陆交互相沉积层，其中陆相物质以古河道的砂层沉积为主，粒度由早期沉积到晚期逐渐变小，古河道沉积层间有较厚的粘土质隔水层。海进时期，大面积的滨海平原被淹没，在近海平原洼地滞留的海水经过蒸发、浓缩作用变为卤水；海退后干冷的环境有利于卤水的进一步蒸发浓缩，通过强透水层下渗。与此同时，海平面下降，裸露的渤海海底沉积物成为莱州湾南岸沉积的主要物源，晚更新世末期地层中沉积了较厚的黄土层，对咸水入侵形成一定的阻隔作用。 由于晚更新世以来的环境变化，在本区形成了卤水与古河道两大沉积体系，它们之间又有着唇齿相依的水力联系。跟据卤水的埋藏特征，可分为潜水卤水和承压卤水，承压卤水浓度高，储量大，分布广，是咸水入侵的主要物质来源。古河道构成了咸水入侵的主要通道，其沉积特征差异对咸水入侵方式及速度有较大的影响。通过分析古河道分布区沉积物的差异，结合地下水水化学资料的分析，阐明了地层沉积特征与咸水入侵的关系。 以古环境为基础的现代环境变化因素，如气候与降水、地下水水位、地下水开采量 等是咸水入侵的驱动因素，其变化特征直接影响着咸水入侵的发展速度。 全文通过对古环境变化及现代环境变化的分析，阐明了沉积环境变化对咸水入侵的 影响，论述了咸水入侵产生的根本原因，并提出了研究咸水入侵的新方法、新角度。更多还原

【Abstract】 Saline water encroachment area can be divided into apparent encroachment and dormant encroachment. The first one is the spread of saline water towards freshwater in nature state, and the second is the fast spread of saline water towards freshwater because of human active work. As one of the typical environment disaster in the south plain of Laizhou Bay, the &%. occurrence of saline water encroachment has close relation with modern environment and ancient environmental evolution. The sediment environmental transformation is the setting factor of saline water encroachment, and the modern environmental change is the spring factor. By analysis the environmental change in the area of Weihe River downstream hi the Laizhou Bay southern Plain, this thesis studies the formation and change of saline water encroachment in the angle of environmental science and sedimentology.By many field reviews and validations in this study, a great number of terra drill data are collected. In the studied area, selecting the typical section, and drilling the bore core sample. Doing the granularity analysis, the sporopollen analysis, microfossil analysis, ’ C and TL (thermoluminescence) age measurement. By the hydrochemical surveillance to the typical section, detailed data of the underground water movement regulation in the transition area of saline water and freshwater are obtained.By the analysis of many sedimentology indexes, the paper does the systematical study on the environment evolution in Weihe River downstream. It also renews and rebuilds the sediment sequence of region paleoenvironment. By contrasting with border area, there are many proper evolution characters under global environment change. Under the differential subsidence tectogenesis control in the Quaternary, the sediment in the area can reach 300 meters in depth, which mainly are coarse sand, medium sand and silt. Because of the Quaternary ice age climate change, there are three times sea level rise fluctuation and sea-triphibian vicissitude since Epipleistocene in the plain, and the sediment environment is the pratum plain and the littoral or shallow water region alternating. Paralic sediments are formed with advance and retreat of beach line, and the continental facies are mainly paleochanle sandy sediment, the grain of whose sediments diminish with the sediment, and there are thick douke aquicludes in it. With the rise of sea level, greatness sea shore PlainIVwas submerged, and the resorted seawater became bittern water by evaporation and concentration. The dry and cold climate after the drop back of sea level is propitious to the evaporation and concentration of bitter water, which seeps down through permeable beds. After the dropping of sea level, the bare Bohai Sea floor becomes the mainly resource of the sediment in south shore of Bohai Sea, which forms the loess sediment in the Late Epipleistocene stratum and is definite permeability barrier to saline water encroachment.With the environmental evolution since the Epipleistocene, the sediment substances of bitter water and paleochanle are formed, which have close water conservancy relation. The bitter water can be divided into phreatic flow bitter water and bearing bitter water by its embedding, and the later is the main resource of saline water encroachment, which has high concentration, abundant reservation and vast distribution. The paleochanles are the main channels of saline water encroachment, the diversity of whose sediment has big influence on the fashion and velocity of saline water encroachment. This paper illustrates the relation of stratum sediment and saline water encroachment, by analyzing the difference of paleochanle sediment and using the ground water hydrochemical data.The recent changing environment factors based on the paleoenvironmental evolution, such as climate and precipitation, groundwater level, and the exploration of groundwater are the driving factors of saline water encroachment, whose change directly influence its velocity.By analyzing the change of paleoenvironme更多还原