长白山地区火山岩中稀土元素特征及赋存状态初探  

Characteristics of Rare Earth Elements in Volcanic Rocks from Changbai Mountain

作　　者：姜赟赟[1,2] 来雅文[1] 段太成[2] 石厚礼[1] 

机构地区：[1]吉林大学地球探测科学与技术学院,吉林长春130026 [2]中国科学院长春应用化学研究所,国家电化学和光谱研究分析中心,吉林长春130022

出　　处：《岩矿测试》2013年第5期825-831,共7页Rock and Mineral Analysis

基　　金：中央高校基本科研业务费“长白山富稀土火山岩稀土元素存在状态研究”项目(20110341);国家自然科学基金资助项目(21275138);国土资源部行业专项“深部探测技术与实验研究”项目(SinoProbe-04-05-02)

摘　　要：长白山地区位于滨太平洋新生代火山区,区内粗面玄武岩广泛分布,面积近20000 km2。该区粗面玄武岩中稀土元素含量很高,如何开采利用不仅取决于其含量,还取决于其赋存状态,但这方面的研究迄今未见报道。本文采用电感耦合等离子体光谱法分析长白山地区火山岩中的主量元素,获得其岩相组成信息,采用电感耦合等离子体质谱法分析稀土元素,由此得到其地球化学特征,并结合分级提取实验,初步探讨长白山火山岩中稀土元素赋存状态。元素分析结果表明,研究区内火山岩的岩性主要以粗面玄武岩和粗面岩为主,稀土元素的总量(∑REEs)为211～893μg/g,其中以粗面岩显著富集稀土元素;粗面岩的δEu为0.06～0.69,具有强烈的负铕异常特性,轻稀土元素与重稀土元素总量比值(∑LREEs/∑HREEs)为3.80～5.61,反映了该区轻、重稀土元素分馏程度较高,且具有富集轻稀土元素的特性。稀土元素的主要赋存状态为磷酸盐结合态(52.9%～88.5%)、碳酸盐结合态(14.6%～43.8%)、氧化物结合态(6.04%～18.4%),而以硅酸盐结合态和离子吸附态存在的稀土元素所占比例最少。分级提取实验分析结果表明,样品的稀土元素总量提取率为91.1%～108%,表明此分级提取方法适合于火山岩中稀土元素赋存状态的分析,为类似火山岩中稀土元素的赋存状态研究提供一种可行性参考方法。Changbai Mountain is located in the circum-pacific Cenozoic volcanic region,where basalt is widely distributed over nearly 20000 km 2,and in which,high contents of rare earth elements（REEs） have been reported.As it is known,the value for utilization of such REE resources depends not only on their contents but also on their existing characteristics,however,no related reports have been made in this respect about the REEs in the Changbai Mountain area so far.In this work,using Inductively Coupled Plasma-Atomic Emission Spectrometry（ICP-AES） and Inductively Coupled Plasma-Mass Spectrometry（ICP-MS）,the main component elements and rare earth elements in the volcanic rocks from Changbai Mountain were both accurately determined,the results revealing that the composition of the rocks is similar to lithofacies of basalt and trachyte,and the amount of the REEs was as high as 211-893 μg / g,with REEs enrichment being more easily found in the latter.Furthermore,negative europium anomalies（δEu） of 0.06-0.69 were observed,and the ratios of light rare earth elements and heavy rare earth elements（∑LREEs / ∑HREEs） had a range of 3.80-5.61,which meant that the LREEs were prone to be more enriched.Finally,a grade extraction procedure was carried out to study the REEs existing phases,the results show that the REEs mainly exist as phosphate phase（52.9%-88.5%）,carbonate phase（14.6%-43.8%） and oxides（6.04%-18.4%）,while those of silicate phase and ion adsorption phase were the least.The grade extraction procedure was proven to be accurate,with recovery yields of 91.1%-108%,providing a feasible strategy for similar analytical purposes.

关 键 词：长白山火山岩 粗面玄武岩 粗面岩 稀土元素 赋存状态 

分 类 号：P588.14[天文地球—岩石学]