白云鄂博地区碳酸岩脉侵位序列与稀土元素富集机制  

Intrusion sequence of carbonatite dykes and REE accumulation mechanism in Bayan Obo district

作　　者：杨奎锋[1] 范宏瑞[1] 胡芳芳[1] 王凯怡[1] 

机构地区：[1]中国科学院地质与地球物理研究所中国科学院矿产资源研究重点实验室,北京100029

出　　处：《岩石学报》2010年第5期1523-1529,共7页Acta Petrologica Sinica

基　　金：国家重点基础研究发展规划项目(2006CB403503);国家自然科学基金项目(40625010和40902028)联合资助

摘　　要：白云鄂博地区发育大量的火成碳酸岩脉。按照矿物组成,碳酸岩脉可分为白云石型、白云石-方解石共存型和方解石型。野外穿插关系表明,白云石型碳酸岩脉形成得早,而方解石型碳酸岩脉形成得晚。白云鄂博地区的碳酸岩浆存在由白云石型到共存型再到方解石型的先后结晶顺序和演化趋势。碳酸岩脉的主量、稀土和微量元素组成特征表明,随着碳酸岩脉中方解石矿物组分的增加,轻稀土元素的含量呈明显富集趋势,而长期的结晶分异作用正是稀土元素,尤其是轻稀土元素在晚期岩浆中强烈富集的内在机制。Three types of carbonatite dykes including dolomite,calcite and coexisted dolomite-calcite are distinguished by mineralogical composition in Bayan Obo rare earth element(REE) deposit district.Incision contact shows that intrusion of calcite carbonatite dykes were later than dolomite type,which indicated that carbonatite magma in Bayan Obo district had special evolution trend from dolomite through coexisted to calcite type.Moreover the content of light rare earth element(LREE) in carbonatite dykes gradually increasing with the proportion of calcite minerals from dolomite through coexisted to calcite type.Geochemical data also shows that long term crystallizational differentiation was the inner mechanism of REE(especially LREE) accumulation in the residual magma.

关 键 词：火成碳酸岩脉 侵位序列 稀土元素富集机制 白云鄂博 

分 类 号：P588.15[天文地球—岩石学]