福建近岸海域表层沉积物稀土元素地球化学特征及其物源指示意义  

RARE EARTH ELEMENT CHARACTERISTICS OF SURFACE SEDIMENTS IN THE FUJIAN COASTAL AREA AND THEIR IMPLICATIONS FOR PROVENANCE

作　　者：李波[1,2] 孙桂华 钟和贤[1,2] 李顺 王艳[3] 赵利 李学杰[1,2] LI Bo SUN Guihua ZHONG Hexian LI Shun WANG Yana ZHAO Li LI Xuejie(Guangzhou Marine Geological Survey. China Geological Survey, Guangzhou 510075, China Key Laboratory of Marine Mineral Resources, Ministry of Land and Resources,Guangzhou 510075,China Guangdong Nonferrous Metals Geological Exploration Institution,Guangzhou 510080,China)

机构地区：[1]中国地质调查局广州海洋地质调查局,广州510075 [2]国土资源部海底矿产资源重点实验室,广州510075 [3]广东省有色地质勘查院,广州510080

出　　处：《海洋地质前沿》2017年第8期47-56,共10页Marine Geology Frontiers

基　　金：国土资源部海底矿产资源重点实验室开放基金课题(KLMMR-2014-A-12);中国地质调查局项目(GZH201200501;DD20160138;DD20160140;DD20160227)

摘　　要：对福建东部近岸海域173个表层沉积物进行稀土元素(REE)含量分析,探讨稀土元素分布特征及影响因素,揭示沉积物物源信息。结果表明,研究区表层沉积物稀土元素总量(ΣREE)分布范围为35.25~296.98μg/g,平均值171.05μg/g,与长江、闽江沉积物的ΣREE非常接近。轻重稀土元素含量比值(LREE/HREE)的变化范围为7.56~16.35,平均值11.27,轻稀土明显富集。REE球粒陨石标准化配分模式以及(La/Sm)CN、(Gd/Yb)CN比值显示,配分曲线为右倾负斜率,LREE内部分异明显,HREE内部分异小,存在中等程度Eu负异常(分布在0.55~1.06,平均值0.80),Ce异常不明显(分布在0.71~1.19,平均值1.00),与上陆壳REE特征相似。REE上陆壳标准化配分模式显示沉积物与上陆壳之间分异不明显,其源岩以上陆壳长英质岩石为主。综合分析认为,研究区表层沉积物REE富集和分布主要受沉积物粒度控制,REE趋向于在细粒组分中富集,局部可能受生物碳酸盐及重矿物含量制约。Rare-earth elements （REE） are analysis for 173 surface sediment samples collected from the Fujian coastal area in order to disclose the controlling factors onto the distribution pattern of REE and their provenance. The total content of rare-earth elements （EREE） for bulk samples ranges from 35.25 to 296.98μg/g with a mean value of 171.05μg/g. The average EREE content of the bulk sedi- ments is quite close to the sediments from the Yangtze and Minjiang Rivers. On the other hand,the ratio of light REE/heavy REE （LREE/HREE） ranges between 7.56 and 16.35 with a mean of 11.27. The enrichment of LREE is quite pronounced in surficial sediments. Both the chondrite -normalized patterns and the ratios of （La/Sm）cN, （Gd/Yb）CN of REE of the sediments from the study area show an accordant steep right-dipping REE distribution pattern with significant fractionation of light REE and weak fractionation of heavy REE. In addition,observed are a moderate negative Eu anomaly ran- ging from 0.55 to 1.06 with a mean value of 0.80 and a less obvious Ce anomaly ranging from 0.71 to 1.19 with a mean value of 1.00. These features are rather similar to the upper continental crust. The upper continental crust-normalized patterns of REE of the sediments show no significant fractionation with respect to the upper continental crust. Therefore, the source of sediments is dominantly from the continental crust consisting of felsic rocks. The enrichment and distribution of REE is generally con- trolled by grain size of sediments. It seems that REE are more enriched in fine-grained fractions. In some areas,REE composition of the sediments is influenced by carbonate and heavy minerals.

关 键 词：福建近岸海域 闽江 表层沉积物 稀土元素 物源 

分 类 号：P736.4[天文地球—海洋地质]