基于XRF岩芯扫描的贵州喀斯特地区晚全新世泥炭古环境研究  

APPLICATION OF XRF CORE SCANNING METHOD IN LATE HOLOCENE ENVIRONMENT CHANGE STUDY DERIVED FROM A PEAT CORE FROM SOUTHWESTERN GUIZHOU,SOUTHWESTERN CHINA

作　　者：杨欢 曾蒙秀 彭海军[2] 李凯[3] 李凤全[1] 朱丽东[1] 邓伯龙 廖梦娜 倪健[3] Yang Huan;Zeng Mengxiu;Peng Haijun;Li Kai;Li Fengquan;Zhu Lidong;Deng Bolong;Liao Mengna;Ni Jian(College of Geography and Environment Sciences,Zhejiang Normal University,Jinhua 321004,Zhejiang;State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,Guizhou;College of Chemistry and Life Sciences,Zhejiang Normal University,Jinhua 321004,Zhejiang;Wetland Protection Center of Guizhou Province,Guiyang 550001,Guizhou)

机构地区：[1]浙江师范大学地理与环境科学学院,浙江金华321004 [2]中国科学院地球化学研究所环境地球化学国家重点实验室,贵州贵阳550081 [3]浙江师范大学化学与生命科学学院,浙江金华321004 [4]贵州省湿地保护中心,贵州贵阳550001

出　　处：《第四纪研究》2020年第5期1154-1169,共16页Quaternary Sciences

基　　金：国家自然科学基金面上项目(批准号:41971111和41773140);国家重点基础研究发展计划项目(批准号:2016YFC0502101)共同资助。

摘　　要：文章选取发育于贵州喀斯特地区的兴义泥炭为研究对象,对钻孔上部300 cm岩芯进行高分辨率XRF连续扫描,并测定了样品含水量、色度(亮度L*、红度a*、黄度b*)和碳酸盐含量。通过对Rb、Ti、Zr、Al、Si、Ca、Sr、Mg等元素含量及其比值、色度和其他代用指标的综合分析,结合主成分分析方法,探讨XRF岩芯扫描在兴义泥炭研究中使用的可行性,并进一步分析兴义泥炭化学元素的来源、指示意义及所记录的古环境演化过程。基于AMS14C测年构建的年代框架,发现:1)XRF岩芯扫描的Ca元素含量与气量法测定的碳酸盐含量具有较好的一致性。XRF岩芯扫描和分光测色计获得的L*、b*相关性高,尽管这两种方法获得的a*存在差异,但其数值表现上相似性仍较高;2)晚全新世以来兴义泥炭的地球化学元素主要来源于周边碳酸盐岩风化、淋溶、随流水搬运而最终沉积到湿地的物质;3)兴义泥炭Sr/Ca比值处于高值,Si/Al、Rb/Sr比值处于低值时,气候偏干,反之则指示气候偏湿润。此外,兴义泥炭Al、Si、Ca、Sr、Mg、Rb/Sr、Si/Al、Sr/Ca的变化趋势与烧失量、腐殖化度等具有较好的一致性;4)晚全新世以来兴义地区总体上呈现出由湿润向干转变的趋势,3270~2700 cal.a B.P.由湿润持续转干,2300~1670 cal.a B.P.降水持续减少,与西南季风主控区众多古环境记录能较好地对应,并揭示了2700~2300 cal.a B.P.降水稳步增加的过程。对兴义泥炭进行XRF岩芯扫描能挖掘其蕴含的物质来源、物质变化特征等多方面信息,有助于拓展XRF岩芯扫描分析方法在泥炭沉积中的应用,并能深化对西南地区古环境演化历史的认识及丰富泥炭研究档案。X-ray fluorescence(XRF)core scanning is a method that has been widely used in loess,marine and lacustrine sediments.The application of this method in peat needs to be further enhanced.In this study,a 300-cm peat drilling core XY1801(25.28°N,104.82°E;1317 m.a.s.l.)from Xingyi peatland in karst region,southwestern Guizhou Province was selected to scan with high resolution XRF.Furthermore,the water content,chromaticity(L*,a*,b*)and carbonate content in Xingyi peat were also measured.Based on the analysis of contents and ratios of Rb,Ti,Zr,Al,Si,Ca,Sr,Mg,chromaticity,humification and other proxies of Xingyi peat,and in combination of the principal component analysis method,this paper discussed the material source of elements,the environmental significances of element contents/ratios,and the recorded paleoenvironment evolution history in and around Xingyi peatland during Late Holocene.Based on the chronological framework constructed by AMS14C dating,the results are shown below.(1)XRF core scanning analysis can achieve ideal results in the research of Xingyi peat,and the element records greatly corresponding to the data obtained by traditional methods.The content of Ca from XRF core scanning coincides well with the carbonate content measured by gas volume method.Furthermore,the variation trend of L*and b*obtained by XRF core scanning and colorimeter is also coincident.The correlation coefficient of L*observed from these two methods is 0.99(P<0.01),and that of b*is 0.91(P<0.01).Moreover,the measured results of a*from these two methods have slightly different due to the influence of sample characteristics and the difference during experimental process.However,the numerical similarity of a*is still high,the correlation coefficient is 0.92 at the 0.01 significance level.(2)Through the analysis of the contents of geochemical elements in Xingyi peat,carbonate weathering process and weathering profiles in karst region,it can be found that the sources of geochemical elements in Xingyi peat are mainly from proximal material.G

关 键 词：贵州泥炭 XRF岩芯扫描 元素地球化学 喀斯特地貌 古环境重建 

分 类 号：P534.63[天文地球—第四纪地质学] P941.78[天文地球—古生物学与地层学]