龙首山芨岭复式岩体岩石地球化学特征及构造环境探讨  

Geochemical Characteristics of Jiling Composite Pluton in Longshou Mountain and Tectonic Environment Discussion

作　　者：汤琳[1,2] 张树明[1,3] 

机构地区：[1]核资源与环境省部共建国家重点实验室培育基地(东华理工大学),江西南昌330013 [2]广东省有色金属地质局九三一队,广东汕头515000 [3]东华理工大学放射性地质与勘探技术国防重点学科实验室,江西南昌330013

出　　处：《东华理工大学学报（自然科学版）》2015年第3期265-272,共8页Journal of East China University of Technology(Natural Science)

基　　金：国家自然科学基金项目"龙首山产于花岗岩中的碱交代型铀矿床成矿机理研究"(41172079)

摘　　要：芨岭复式岩体位于甘肃龙首山拱断带中段,产有芨岭等我国最为典型的碱交代型铀矿床,为揭示其成因意义,并初步探讨其构造环境,对芨岭复式岩体进行了地球化学研究。地球化学及岩石学研究表明,芨岭复式岩体岩石属于低硅(47.09%~73.71%)、低钾高钠(K2O/Na2O平均值<1)、准铝质高钾钙碱性系列岩石。微量元素相对富集Ba,Rb,Th,U等大离子亲石元素(LILE)且相对贫Ta,Nb,Zr,Hf,Ti,P等高场强元素(HFSE)。具有明显的Th,U富集,La,Ce正异常,Zr,Hf弱亏损,Sr,P,Ti强烈亏损特征。稀土元素含量较高且表现出轻稀土元素(LREE)富集,重稀土元素(HREE)较为平坦特征。应用微量元素构造判别图解,并结合前人对该区构造-岩浆演化的长期研究,认为芨岭复式岩体很可能形成于碰撞后构造背景。Jiling composite rock body,which is located in the center of Longshoushan,Gansu,outputs typical alkali metasomatism type uranium deposits of our country,such as Jiling deposit. In order to reveal the significance of its petrogenesis and preliminary discuss its structural environment,the geochemistry of Ji Ling composite rock body are studied. Geochemical and petrologic data show that Jiling composite rock body is characterized by low silicon( 47. 09% ~ 73. 71%),low potassium and high sodium( K2 O / Na2 O average value < 1),and it belong to metaluminous high-K calc-alkali rock. Trace elements analysis shows that it is relatively enrichment of Ba,Rb,Th,U and other large LILE,and relatively poor high field strength elements( HFSE),such as Ta,Nb,Zr,Hf,Ti and P,and trace elements has the features of obvious Th,U enrichment,La,Ce positive anomalies,Zr,Hf weak loss,Sr,P,Ti strongly depleted. With high REE contents,REE exhibit high LREE and relatively low HREE features. Application of trace element tectonic discrimination diagrams,and combined with the previous long-term studies on tectono-magmatic evolution of this district,we think that Jiling composite pluton is likely to be formed after the collision tectonic setting.

关 键 词：芨岭复式岩体 岩石地球化学 构造环境 龙首山 

分 类 号：P619.14[天文地球—矿床学]