黄河下游大野泽沉积物粒度特征及其对环境演化的指示  

Grain-size characteristics of Dayeze lake sediments in the lower reach of Yellow River and their environmental implications

作　　者：魏本杰 侯战方 陈诗越 孟静静[1,2] 伏梦璇 杨丽伟 刘晓迪 刘加珍[1] 陈影影[3] 衣雅男 WEI Benjie;HOU Zhanfang;CHEN Shiyue;MENG Jingjing;FU Mengxuan;YANG Liwei;LIU Xiaodi;LIU Jiazhen;CHEN Yingying;YI Yanan(School of Environment and Planning,Liaocheng University,Liaocheng 252000,China;State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,CAS、Xi'an 110061,China;School of Geography,Geoma tics,and Planning,Jiangsu Normal University,Xuzhou 221116 China)

机构地区：[1]聊城大学环境与规划学院,聊城252000 [2]中国科学院地球环境研究所黄土与第四纪国家重点实验室,西安710061 [3]江苏师范大学地理测绘与城乡规划学院,徐州221116

出　　处：《海洋地质与第四纪地质》2019年第3期151-161,共11页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金青年项目“历史时期黄河下游安山湖湿地演变及其与黄河-运河关系的研究”(41702373);国家自然科学基金面上项目“2万年以来黄河下游季风演变及洪水与河道变迁机制研究”(41672345),“历史时期黄河下游湖泊消亡过程及机制与沉积碳埋藏量估算”(41871073);黄土与第四纪地质国家重点实验室开放基金项目“鲁西南安山湖形成、演化与黄河改道变迁的关系研究”(SKLLQG1509)

摘　　要：利用黄河下游湖泊大野泽550cm柱状岩芯沉积物粒度分析,结合高精度的AMS 14C年代测定,初步揭示了研究区近1400a来湖泊沉积及环境演化历史。应用沉积物粒度频率分布曲线和概率累积曲线分析,结合沉积物岩性特征,结果发现DYZ-1钻孔地层明显分为两个沉积阶段:550~385cm,以深黑色和青灰色黏土质粉砂和粉砂质黏土为主,属湖沼相沉积物环境;385~30cm,以棕黄色和浅黄色黏土质粉砂为主,为河流相沉积环境。综合粒度组成和粒度参数分析结果,大野泽近1400a环境演变可以大致划分为5个阶段:625-940 AD期间,为湖泊水位较低沼泽相沉积环境,气候较干冷;940-1250 AD期间,在中世纪暖湿气候背景下,湖盆频受黄河洪水入注,湖盆扩张,水位抬高;1194 AD开始,黄河河道南迁至黄海入海,大野泽逐渐演变为河流相沉积;1250-1540 AD期间,河流水动力较强,气候较湿润;1540-1860 AD期间,河流水动力表现出减弱趋势,气候转干冷,对应小冰期;1860 AD之后,黄河再次改道北迁至渤海入海,大野泽再次接受黄河洪泛注入,但由于前期湖区抬高成陆,该区域仅作为黄河泥沙承载区。This paper is devoted to the grain-size characteristics of a 550-cm-long sediment core,which was retrieved from the Lake Dayeze,a waterbody used to connect to the Lower Yellow River(LYR),with the purpose to reveal the environmental changes of the LYR during the last 1400 a.The sediments are dated by high-precision AMS 14C dating.According to the grain size frequency distribution curve and cumulative probability curve of the sediments,in addition to lithological characteristics,the changes in depositional environment of the study area is divided to two phases:the 550~385 cm composed of dark-grey clay and dark-grey caesious clay,belongs to a lacustrine sedimentary environment;the 385~30 cm composed of yellow-brown silt and light yellow clay,is deposited in a fluvial environment.By Integration of grain size composition and grain size parameters,as well as historical documents,we inferred that the lake has experienced five distinct stages of environment evolution during the last 1400 years.There was a low level swamp environment during 625-940 AD,under dry and cold climate conditions in the study area.Then the lake level rose and the lake expanded due to flooding,under warm and wet climate conditions during 940-1250 AD,corresponding to the Medieval Warm Epoch.During 1250-1540 AD,it was characterized by strong hydrodynamic force under a fluvial environment and relatively humid climate,and then,the river hydrodynamic weakened,the climate became dry and cold again,corresponding to Little Ice Age.The channel of the LYR shifted back and discharged into Bohai Bay,by the 1855 AD flooding event.As a result,the study area was affected by the flooding events of the LYR again.

关 键 词：粒度特征 沉积环境 改道决溢 大野泽 

分 类 号：P736.2[天文地球—海洋地质]