黄河水下三角洲钻孔沉积物磁学记录及其年代学意义  

Environmental magnetic properties of core sediments in the Yellow River subaqueous delta and their chronological applications

作　　者：陈艇 刘青松 郑一 Ting Chen;Qingsong Liu;Yi Zheng(Chongqing Key Laboratory of Earth Surface Processes and Environmental Remote Sensing in Three Gorges Reservoir Area,Chongqing Normal University,Chongqing 401331,China;Centre for Marine Magnetism,Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;School of Environmental Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,China)

机构地区：[1]重庆师范大学,三峡库区地表过程与环境遥感重庆市重点实验室,重庆401331 [2]南方科技大学海洋科学与工程系海洋磁学中心,深圳518055 [3]南方海洋科学与工程广东省实验室(广州),广州511458 [4]南方科技大学环境科学与工程学院,深圳518055

出　　处：《科学通报》2021年第30期3902-3915,共14页Chinese Science Bulletin

基　　金：重庆师范大学博士启动/人才引进项目(20XLB021);国家自然科学基金(51961125203,41904069)资助。

摘　　要：自1976年从清水沟入海之后,黄河受水库修建、水土保持等自然与人类活动影响强烈,入海泥沙逐年减少.2002年,黄河开始调水调沙,进一步改变了黄河入海泥沙格局.目前,已有较多研究通过水深测量、遥感等方法研究黄河三角洲的冲淤演变,但还较缺乏沉积记录方面的支持.以1976年以来黄河入海口附近水下三角洲沉积钻孔YD01、YD02和YD03为材料,对3个钻孔进行详细的环境磁学和岩性分析,探讨1976年以来黄河口水下三角洲沉积物磁学特征,及其对黄河闾尾摆动、流域水库建设、调水调沙等活动的响应,及可能的年代学意义.研究结果表明,YD01、YD02和YD03孔磁学参数χ_(fd)%、χ_(ARM)和岩性特征较灵敏地响应了1976年黄河改道经清水沟入海、1986年龙羊峡水库建设、2002年黄河调水调沙及2007年左右调水调沙能力减弱等自然和人类活动与过程.在3个钻孔中,这些磁学和岩性特征变化显著的界面可以作为黄河口沉积物定年的参考点.The Yellow River has shifted frequently in the downstream region since 1885;it has flowed into the sea through the Qingshuigou channel from 1976 onward,thus forming the latest delta lobe(1976–present).During the past~40 years,the sediment load of the Yellow River has been greatly reduced because of human and natural activities,such as reservoir construction,soil and water conservation,and river avulsion.Beginning in 2002,the water-sediment regulation scheme(WSRS)has also changed the sediment loading patterns of the Yellow River.Several studies have reported on the erosion and deposition characteristics of the latest lobe of the Yellow River Delta over the past several decades,based on remote sensing methods and water-depth measurements.However,continuous sedimentary records of delta erosion and deposition and their responses to natural and human activities in the watershed are lacking.Here,we obtained three sediments cores,YD01,YD02,and YD03,from the subaqueous delta of the latest lobe of the Yellow River Delta.These cores contain sediments deposited from 1976 to 2018.We analyzed the environmental magnetism and lithological characteristics of these cores,and investigated their responses to natural and human activities in the watershed of the Yellow River,as well as possible applications to sediment dating in the Yellow River Delta.The results show that frequency-dependent susceptibility(χ_(fd)%)and anhysteretic remanent magnetization susceptibility(χ_(ARM))values were high in core sediments deposited from 1976 to 1996,indicating abundant contents of fine single-domain(SD)and superparamagnetic(SP)magnetic particles,and therefore a dominant sediment supply from the Chinese Loess Plateau.Small decreases in χ_(fd)% and χ_(ARM) in sediments deposited after 1986 revealed slight reduction of the sediment load from the Yellow River,which was likely caused by sediment retention related to the construction of the Longyangxia Reservoir.Rapid rises in χ_(fd)% and χ_(ARM) occurred in core YD01 sediments deposited duri

关 键 词：黄河三角洲 调水调沙 环境磁学 黄河改道 泥沙来源 

分 类 号：P512.2[天文地球—地质学] P597.3P343.5