衡阳盆地红土剖面元素地球化学特征及其古环境意义  

Geochemistry of Elements and Its Paleoenvironmental Implications from the Red Earth Profile in the Hengyang Basin

作　　者：熊平生 王鹏 张忆 张楚楚 XIONG Pingsheng;WANG Peng;ZHANG Yi;ZHANG Chuchu(Hengyang Normal University College of City and Tourism,Hengyang 421002,Hunan,China;Hengyang Normal University College of Nanyue,Hengyang 421000,Hunan,China)

机构地区：[1]衡阳师范学院城市与旅游学院,湖南衡阳421002 [2]衡阳师范学院南岳学院,湖南衡阳421000

出　　处：《山地学报》2019年第5期693-701,共9页Mountain Research

基　　金：国家自然科学基金资助项目(41471153);大学生创新创业训练计划项目(201912659001,NYD201905)。

摘　　要：为了揭示衡阳盆地红土剖面沉积的古环境信息,对高兴红土剖面进行电子自旋共振(ESR)测年和常量、微量元素测试分析.结果表明:(1)红土剖面常量元素氧化物组成以SiO2、Al2O3、Fe2O3为主,三者含量总和为89.63%.微量元素Rb、Sr、Ba、Cu含量分别与常量元素氧化物K2O、MgO、Na2O、Al2O3含量之间表现出显著的正相关性,Na2O、MgO、K2O、Al2O3含量之间呈显著正相关性,表明它们的活动性相似.(2)高兴剖面绝大多数常量元素氧化物在风化过程中表现为迁移淋失,Fe2O3、SiO2则表现为轻度富集,常量元素的迁移能力大小顺序依次为:K2O>Na2O>MgO>Al2O3>SiO2>Fe2O3.MgO、Na2O、K2O、Al2O3自剖面底部往上迁移程度逐渐减弱的变化趋势,表明沉积时期气候的湿热程度也逐渐减弱.(3)CIA值、Rb/Sr值从剖面顶部往下呈递增的趋势,而微量元素Rb含量、Sr含量、Sr/Cu值、Sr/Ba值呈现相反的变化趋势.CIA值、Rb/Sr值、Sr/Cu值、Sr/Ba值曲线共同印证了2.23 Ma以来的衡阳盆地气候演化特征,即为由炎热潮湿向温暖湿润方向的变化.Global climate and environmental changes and regional responses are hot topics of widely concerned in Geosciences areas.In order to reveal the paleoenvironmental information of red clay sediments in Hengyang Basin,major elements,trace elements and Electron Spin Resonance(ESR)dating of red clay samples from the Gaoxing profile were measured and analyzed.The results showed that:(1)SiO2,A1203 and Fe203 were the main components of major element oxides in red clay profile,and their total content was 89.63%.With slightly more than 1%,the contents of MgO,K2O,CaO and Na2 O were very low of red clay samples,except K2 O was easily adsorbed by red clay.The contents of other soluble components were all less than 1%.The percent contents of trace elements Ba,Cu,Rb and Sr were positively correlated with the contents of major elements K20,MgO,Na2 O and A1203 respectively,and the contents of Na20,MgO,K2 O and A1203 were positively correlated with each other,indicating that their activities were similar.(2)Geochemical behavior of major element oxides K2 O,MgO,Na2 O and A1203 was characterized by migration and leaching,while the element oxide of SiO2 and Fe2 O3 were slightly enriched.Relative migration ability was in the order of K2 O>Na2 O>MgO>Al2 O3>SiO2>Fe2 O3.The migration of MgO,Na2 O,K2 O,Al2 O3 from bottom to top of the profile tends to weaken gradually,indicating that the humidity and heat of the climate during the sedimentary period were also weakening gradually.(3)The values of CIA and Rb/Sr increased from top to bottom,while the contents of Rb,Sr,Sr/Cu and Sr/Ba decreased.The CIA value,Rb/Sr value,Sr/Cu value and Sr/Ba value revealed that the climate of Hengyang Basin had evolved from being hot-humid to being warm-wet since 2.23 Ma.

关 键 词：化学蚀变指数 元素迁移 微量元素 红土 衡阳盆地 

分 类 号：P595[天文地球—地球化学]