中国东部入海河流沉积物磁性矿物化学特征及物源意义  

GEOCHEMICAL PROPERTIES OF MAGNETIC MINERAL IN THE EASTERN CHINA RIVER SEDIMENTS AND THEIR PROVENANCE IMPLICATIONS

作　　者：马骏强[1] 岳伟[1] 刘健辉[1] 刘演[1] 张丹[1] 陈静[1] 

机构地区：[1]华东师范大学河口海岸学国家重点实验室,上海200062

出　　处：《第四纪研究》2017年第1期57-66,共10页Quaternary Sciences

基　　金：国家自然科学基金项目（批准号：41301214）资助,致谢 感谢审稿专家和杨美芳老师对本文修改提出的宝贵意见.

摘　　要：大量陆源碎屑物质主要通过以长江、黄河为代表的大江大河和以瓯江、浊水溪为代表的山溪性小河流的携带输移至中国东部海域，海域沉积物的物源识别是当前的研究热点。本文通过原子吸收光谱法测试了磁性矿物中的11种元素（Ti、Fe、Cr、Mg、Al、V、Ca、Co、Zn、Mn和S），旨在探讨这些河流沉积物（〈45μm）的磁性矿物群体化学特征，提取其物源指示意义，为边缘海沉积物物源判别提供依据。研究结果表明，这些河流沉积物的磁性矿物主要是以铁氧化物（磁铁矿）为主，铁硫化物含量很低（〈2%），只有台湾浊水溪沉积物中含有相对较多的铁硫化物（主要是磁黄铁矿），为1.84%。除此之外，各河流沉积物磁性矿物中铁氧化物的化学元素组成（Ti、Mg、Ca、Al、Cr、V、Mn、Co和Zn）差异也很明显，其中黄河富含Mg和Ca，长江富含Ti，钱塘江富含Al，瓯江富含Cr，台湾浊水溪相对来说富含Al和Co，而其余元素含量远低于其他河流。从磁性矿物成因图上看，黄河沉积物中磁性矿物落在碱性岩浆岩成因区，但这并不是反映了流域磁性矿物的母岩为碱性岩浆岩，而是由于流域中黄土土壤化过程中产生的细颗粒磁性矿物中含有较高的碱土金属元素（如Mg和Ca）所致；其他河流磁性矿物成因与其流域母岩关系密切，如长江和浙闽河流主要为超基性-基性-中性岩浆岩成因，浊水溪为沉积变质-接触交代成因，都与其所处流域的磁性矿物的母岩类型较为一致。利用Ti＋V-S＋Co-Ca＋Mg三角图可以有效地区分黄河、长江和浙闽河流、浊水溪沉积物物源。磁性矿物群体中的Mn、Zn、Al、Cr元素的差异有助于进一步确定长江和浙闽河流的泥沙来源。同时，发现磁性矿物单颗粒和群体化学组成特征具有一定差异性，很可能是由于分析方法不同所造成。The Chinese marginal seas are mostly fed by terrestrial sediments not only through large rivers such as Yellow River and Yangtze River, but also through small mountainous rivers including Qiantang River, Ou River, Min River and Taiwan rivers. Sediment supplies of these small mountainous rivers to the sea have attracted more attentions recently. To trace the source of marine sediments, it is necessary to understand provenance differences among all above rivers and set up an effective provenance indicator firstly. The paper aimed to find the riverine sediment provenance differences through analyzing the geochemical properties of magnetite mineral group in the fine sediments（〈45 μm） from Yellow River, Yangtze River, Qiantang River, Ou River, Min River and Zhuoshui River. Eleven elements（Ti, Fe, Cr, Mg, Al, V,Ca, Co, Zn, Mn and S）of magnetite mineral group were measured by atomic absorption spectrometry. The results showed that：（1）Iron oxide（mainly magnetite）dominated magnetic minerals of all the rivers＇ sediments. Iron sulfide rarely existed in all the riverine sediments（〈2%）. By comparison, Zhuoshui River was richer in iron sulfide（mainly pyrrhotite） （1.84%）. （2）There were obvious differences among the rivers in many elements of magnetic mineral, such as Ti, Mg, Ca, Al, Cr, V, Mn, Co and Zn. The representative elements of magnetite mineral were Mg and Ca for Yellow River, Ti for Yangtze River, Al for Qiantang River, Cr for Ou River, Al and Co for Zhuoshui River. Notably, contents of Ti, Mg, Ca, Mn, Cr, V and Zn of the magnetic minerals were very low in Zhuoshui River compared with the other rivers. （3）In terms of magnetite genetic diagram, magnetic minerals of Yellow River, Yangtze River and Zhejiang-Fujian rivers showed an igneous origin, while magnetic minerals of Zhuoshui River originated from metamorphic rocks. Generally, magnetic minerals in the riverine sediments were mainly derived from source rocks or weathering process of the drainage basins. Magnetic minerals o

关 键 词：磁性矿物 物源 浙闽河流 台湾浊水溪 化学元素组成 

分 类 号：P737.121[天文地球—海洋地质] P595[天文地球—海洋科学]