江汉平原湖相沉积物元素地球化学记录揭示的12.8 cal. ka BP以来气候环境演变  

Evolution of climate in the Jianghan Plain:evidence from elemental geochemical records oflacustrine sediments since 12.8 cal.ka BP

作　　者：罗文菁 吴立 朱诚[2] 马春梅[2] 路曙光 李晨晨 李肖雪 LUO Wenjing;WU Li;ZHU Cheng;MA Chunmei;LU Shuguang;LI Chenchen;LI Xiaoxue(School of Geography and Tourism,Anhui Normal University,Wuhu 241002,China;School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China)

机构地区：[1]安徽师范大学地理与旅游学院,芜湖241002 [2]南京大学地理与海洋科学学院,南京210023

出　　处：《地球环境学报》2024年第2期290-305,共16页Journal of Earth Environment

基　　金：国家自然科学基金项目(41771221,41977389);安徽省“十四五”规划重点项目(2022BFAFZ01365);国家重点研发计划(2020YFC1521605)。

摘　　要：以江汉平原JZ-2010湖相沉积剖面为研究对象,AMS14C年代数据为框架,通过对湖相沉积物的元素地球化学记录进行综合分析与对比研究,重建了江汉平原冰消期末至全新世以来的古环境演化过程,并探讨了区域气候变化的可能驱动因素。结果表明:12.8—9.1 cal.ka BP,研究区气候总体上温凉偏干,但有逐渐向暖湿变化的趋势;9.1—6.3 cal.ka BP,气候温暖湿润,水热配置均匀;6.3—4.4 cal.ka BP,气候前期较为暖湿,后期有逐渐向干旱转变的趋势;4.4—1.3 cal.ka BP,气候经历4.2 ka冷干事件后逐渐向温暖湿润转变。硅铝率、CIA和Rb/Sr指标的变化趋势与太阳辐射量、北大西洋赤铁矿染色颗粒及底栖有孔虫壳体δ^(13)C记录之间存在较好的对应关系,揭示出江汉平原12.8 cal.ka BP以来的气候变化受控于北大西洋深水流的变化,同时,中晚全新世以来气候变化趋势与北半球夏季太阳辐射变化趋势较为吻合,太阳辐射主要通过季风环流间接影响区域气候变化。Background,aim,and scope The Jianghan Plain is a typical flood plain composed of inter-river depressions,with alternating fluvial and lacustrine sediments that are sensitive to climate change and contain a large amount of paleoclimate information.Therefore,it is an ideal place to study paleoclimate.Previous studies have mostly concentrated on magnetic susceptibility,particle size,and pollen assemblages.However,it is insufficient to reconstruct the climatic and environmental evolution of Jianghan Plain from the end of the deglacial to the Holocene through the combination of regular trace elements in lacustrine sediments and geochemical analysis methods on a longer time scale.Based on the analysis oflacustrine sedimentary geochemical elements,we aimed to reconstruct the climatic and environmental evolution of the Jianghan Plain from the end of the deglacial to the Holocene and discuss the possible driving factors of this change.Materials and methods A lacustrine sedimentary section(numbered JZ-2010)in Jingzhou,with a thickness of 637 cm was selected for sampling,which was composed of silty clay rich in organic matter.Furthermore,only the lacustrine sedimentary section in the middle and lower parts was sampled,and that in the upper part was not discussed due to flood disturbances.The lacustrine sedimentary section in the middle and lower parts was further subdivided into nine layers,and 206 samples were collected from bottom to top at 2 cm intervals.X-ray fluorescence spectroscopy(XRF)was used to determine the composition of geochemical elements.To establish the sedimentary chronosequence,six samples were collected from the middle and lower parts of the section for accelerator mass spectrometry radiocarbon(AMS 14C)dating.The samples ware jointly performed by the AMS 14C Sample Preparation Laboratory of Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,and the State Key Laboratory of Nuclear Physics and Technology,Peking University.Results The results showed that from 12.8 to 9.1 cal.ka BP,the climate o

关 键 词：江汉平原 湖相沉积 元素地球化学 环境演变 

分 类 号：P512.2[天文地球—地质学] P595P532