摘要
为研究黄河口和长江口沉积物的物源特征,用电子探针对两地沉积物中的绿帘石进行了单矿物主要元素分析,用电感耦合等离子体光谱对长江口绿帘石群体矿物进行了主、微量元素分析。绿帘石单矿物分析结果表明,黄河口和长江口绿帘石的主要组成元素具有相似的地球化学特征,均表现为高铁、钠而低铝、钾。绿帘石群体矿物分析结果表明,长江口沉积绿帘石的主要元素成分与单矿物的一致,但其Sr、V、Cr、Zr、Pb、REE等元素富集显著。通过8个阳离子方法计算得到黄河口和长江口沉积绿帘石的化学式分别为Ca(2.050-3.426)Fe^3+(0.106-0.606)Al(0.833-1.716)[Si(3.486-4.300)O12]OH,Ca(1.908-3.336)Fe^3+(0.094-0.607)Al(0.911-1.691)[Si(3.542-4.420)O12]OH。计算得到两地绿帘石的Xps值大多为0.19~0.30,并且TiO2含量大都小于0.2%,表明绿帘石族矿物中主要为绿帘石、少量为斜黝帘石,并且成因以岩浆成因为主,热液蚀变成因次之,变质成因较少。不同成因绿帘石的多少与河流中上游地区的地质条件密切相关。统计发现,变质成因绿帘石黄河口较长江口高出2%左右,反映其物源区更为宽泛。沉积绿帘石的元素地球化学特征可用于黄河和长江沉积物的物源判识。
In order to study provenance characteristics of sediments in estuaries of the Yellow River and Yangtze River,single mineral chemical compositions of epidotes from sediments in estuaries of the Yellow River and Yangtze River and main and trace elements of epidote separates(a certain amount of epidote grains in a sample)from sediments in the Yangtze River estuary have been analyzed by using electron microprobe and inductively coupled plasma spectrometry,respectively.The electron probe analyses of main components of individual epidote grains from sediments in estuaries of the Yellow River and the Yangtze River show that they have similar geochemical characteristics as they both have relatively high contents of Fe and Na but relatively low contents of Al and K.The analyses of the epidote separates show that the major element compositions of epidotes from sediments in the Yangtze River estuary are consistent with the electron microprobe analytical results of individual epidotes.In addition,those epidotes are significantly enriched in Sr,V,Cr,Zr,Pb,and REE.Through the eight cationic calculation method,the chemical formulas of epidotes from sediments deposited in estuaries of the Yellow River and Yangtze River are Ca(2.050-3.426)Fe3+(0.106-0.606)Al(0.833-1.716)[Si(3.486-4.300)O12]OH and Ca(1.908-3.336)Fe3+(0.094-0.607)Al(0.911-1.691)[Si(3.542-4.420)O12]OH;respectively.The epidotes from those two areas have calculated Xps values of mostly 0.19-0.30 and TiO2 contents of mostly less than 0.2%.These show that those epidote separates contain major epidote and minor clinozoisite,with their genesis of dominant magmatic,second hydrothermal alteration,and third metamorphic origins.The amounts of different genetic epidote grains are closely related to the geological conditions in the middle and upper streams of those two rivers.It was found that the content of metamorphic epidotes in sediments from the Yellow River estuary is about 2%higher than that in sediments from the Yangtze River estuary,reflecting that those epidotes were
作者
张伟
金秉福
岳伟
王孟瑶
ZHANG Wei;JIN Bing-fu;YUE Wei;WANG Meng-yao(School of Resources and Environmental Engineering,Ludong University,Yantai Shandong 264025,China;School of Geography,Geomatics and Planning,Jiangsu Normal University,Xuzhou Jiangsu 221116,China;State Key Laboratory for Estuarine and Coastal Research,East China Normal University,Shanghai 200062,China)
出处
《矿物岩石地球化学通报》
CAS
CSCD
北大核心
2020年第3期576-586,共11页
Bulletin of Mineralogy, Petrology and Geochemistry
基金
国家自然科学基金项目(41576057)。
关键词
绿帘石
地球化学
矿物成因
物源
黄河
长江
epidote
geochemistry
mineral genesis
provenance
Yellow River
Yangtze River
