莱州湾滨海平原沉积环境对古卤水盐分迁移能力的影响  

Influence of the sedimentary environment on the salt migration ability of ancient brine in the coastal plain of Laizhou Bay

作　　者：韩汝杰 李静 李晓波 HAN Rujie;LI Jing;LI Xiaobo(School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430078,China;No.5 Exploration Institute of Geology and Mineral Resources of Shandong Province,Taian Shandong 271000,China)

机构地区：[1]中国地质大学(武汉)环境学院,武汉430078 [2]山东省第五地质矿产勘查院,山东泰安271000

出　　处：《地质科技通报》2024年第5期259-271,共13页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金项目(41977167,423377071);广西重点研发计划项目(桂科AB21196026)。

摘　　要：海岸带沉积环境是研究地下水演化与运移的基础。为探讨莱州湾南岸沉积环境对咸-淡地下水空间分布及迁移能力的影响,钻探采集了2个第四纪典型钻孔(LZ01和LZ02)样品,利用压榨法提取了孔隙水,测定了沉积物的粒度组成和孔隙水Cl^(-)浓度。结果表明,2个钻孔均以细粒沉积物为主,平均粒径为5.5?。根据沉积物岩性和粒度参数特征,得出LZ01与LZ02钻孔分别包含10、9个沉积相态交替,揭露了晚更新世以来的3套海相地层单元。孔隙水以卤(咸)水为主,Cl^(-)浓度剖面形态呈现3个峰值,3个卤水层分别与3套海相地层对应,表明沉积物中残留海相古卤水,并向相邻沉积物中扩散。沉积物的水动力指数与Cl^(-)浓度垂向变化率呈现明显的分区性;中等水动力条件下,孔隙水Cl^(-)扩散迁移能力强。敏感粒径分析表明孔隙水迁移的优势粒径范围为45.61~111.47μm。研究区古海侵事件控制了卤水的分布,而低渗透性及岩性组合对封存古卤水起着重要作用。研究结果可为莱州湾滨海平原卤水成因、地下水咸化及运移研究提供理论依据。[Objective]The coastal sedimentary environment is fundamental to the comprehending the evolution and movement of groundwater.To investigate the impact of the distribution and mobility of brackish groundwater along the southern coast of Laizhou Bay,[Methods]this study collected samples from two archetypal Quaternary boreholes(LZ01 and LZ02),extracted pore water using the mechanical squeezing technique,and measured the grain size composition of the sediments and the Cl^(-)content of the pore water.[Results]Both boreholes are dominated by fine-grained sediments with an average particle size of 5.5∅.Based on the sediment lithology and grain size parameters,it was found that the LZ01 and LZ02 boreholes contained 10 and 9 alternating sedimentary facies,respectively,revealing three sets of marine stratigraphic units since the late Pleistocene.The porewater was found to be predominantly composed of brine(saline)water,with the Cl^(-)profile displaying three peaks corresponding to the three sets of marine stratigraphic units.These results demonstrate the presence of residual ancient marine brine water in the sediment and its permeation into neighboring sediments.In this study,it was observed that the hydraulic index of sedimentary water exhibited a clear zonal pattern,with the vertical change rate of Cl^(-)serving as a crucial indicator.Notably,under moderate hydraulic conditions,Cl^(-)displayed a robust diffusion and migration capability in pore water,as confirmed by detailed particle size analysis.The dominant particle size range for pore water migration was 45.61-111.47μm.[Conclusion]The paleo-marine transgression events in the study area controlled the distribution of brine,while low permeability and lithological combinations played a significant role in the preservation of ancient brine.The results of this study provide a theoretical basis for research on the origin of brine,groundwater salinization,and migration in the Laizhou Bay coastal plain.

关 键 词：莱州湾 沉积环境 海相地层单元 水动力强度 Cl^(-)浓度 

分 类 号：P641[天文地球—地质矿产勘探]