赛马碱性杂岩体的岩浆演化与稀土富集  

Magmatic evolution and rare earth element enrichment of Saima alkaline complex,Liaoning,China

作　　者：付瑞鑫 李宁波[1,3] 牛贺才[1,3] 单强[1,3] 赵旭[1,3] 刘堃 FU RuiXin;Li NingBo;NIU HeCai;SHAN Qiang;ZHAO Xu;LIU Kun(CAS Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;Center of Excellence for Deep Earth Sciences,Chinese Academy of Sciences,Guangzhou 510640,China;Xinshun Mining Co.,Ltd.Sichuan,Chengdu 610041,China)

机构地区：[1]中国科学院广州地球化学研究所矿物与成矿重点实验室,广州510640 [2]中国科学院大学,北京100049 [3]中国科学院深地科学卓越创新中心,广州510640 [4]四川鑫顺矿业股份有限公司,成都610041

出　　处：《岩石学报》2023年第10期2951-2967,共17页Acta Petrologica Sinica

基　　金：国家重点研发计划项目(2021YFC2901705);国家自然科学基金项目(41930424);广东省科技计划(2020B1212060055)联合资助.

摘　　要：赛马碱性杂岩体位于我国辽东半岛,是一个典型的铀-铌和稀土多金属矿化杂岩体,富含重稀土,其复杂的演化过程和稀土元素富集机制仍没有得到有效约束。本文对该碱性杂岩体中角闪辉石正长岩、正长岩、黑云正长岩、云霓霞石正长岩和异霞正长岩5类岩石及锆石的元素地球化学特征进行了系统研究,并开展了特征矿物包裹体的显微岩相学研究,旨在限定杂岩体母岩浆的演化路径,揭示稀土元素的富集机制。研究结果显示,赛马碱性杂岩体的母岩浆经历了由钾质碱性(角闪辉石正长岩、正长岩和黑云正长岩),到钾质过碱性(云霓霞石正长岩),向钠质过碱性(异霞正长岩)的充分演化。在演化过程中赛马碱性杂岩体母岩浆的体系状态发生了明显变化,碱性岩浆演化受流体不饱和的纯岩浆体系的控制,而过碱性岩浆岩则形成于流体过饱和的岩浆体系,且异霞正长岩母岩浆流体的饱和程度明显高于云霓霞石正长岩的母岩浆。研究还显示,钾质碱性岩浆稀土元素的地球化学行为主要受控于磷灰石等矿物的分离结晶,而成矿的钠质过碱性岩浆稀土、锆和铌等元素的富集成矿则主要受富CO_(2)的高盐度岩浆热液的控制。The Saima alkaline complex(petrologically including hornblende-pyroxene syenite,syenite,biotite syenite ijolite syenite and lujauvrite)with uranium and rare earth element(REE)mineralization is located in the Liaodong Peninsula,China.In this study,an integrated study of petrography,whole rock geochemistry,zircon geochemistry and fluid inclusion were presented to constrain the petrogenesis and metallogenic mechanism of this complex.The results show that the parent magma of the complex has undergone a progressive evolution from potassium alkaline(hornblendite syenite,syenite,and biotite syenite)through potassium peralkaline(ijolite syenite)to sodium alkaline(lujauvrite).This evolution process is mainly controlled by the transition from volatile-undersaturated to oversaturated conditions.The peralkaline rocks generate in the latest stage were formed in the volatile oversaturated condition,and the magma of the mineralized lujauvrite contains more fluids than that of the ijolite syenite.The geochemical behavior of the REE in the alkaline rocks were mainly controlled by the fractional crystallization of apatite,but the enrichment and mineralization of REE,Zr,and Nb in the mineralized lujauvrite were controlled by the evolution of the CO_(2)-rich and high-salinity magmatic-hydrothermal fluids.

关 键 词：赛马碱性杂岩体 岩浆演化 岩浆热液 稀土元素 富集成矿 

分 类 号：P588.15[天文地球—岩石学] P618.7[天文地球—地质学]