胶东大疃刘家铍矿床碱性岩岩石成因及对成矿的制约:锆石U-Pb年代学、地球化学及Sr-Nd-Hf同位素证据  

Petrogenesis of alkaline rocks in Datuanliujia Be deposit,Jiaodong Peninsula,and its constraint on mineralization:Evidence from zircon U-Pb geochronology,geochemistry and Sr-Nd-Hf isotopes

作　　者：唐文龙 邹键 张锋 党智财 TANG WenLong;ZOU Jian;ZHANG Feng;DANG ZhiCai(Tianjin Center,China Geology Survey(North China Center of Geoscience Innovation),Tianjin 300170,China;Exploration Institute of Geology and Mineral Resources,Yantai 264004,China)

机构地区：[1]中国地质调查局天津地质调查中心(华北地质科技创新中心),天津300170 [2]山东省第三地质矿产勘查院,烟台264004

出　　处：《岩石学报》2024年第8期2429-2449,共21页Acta Petrologica Sinica

基　　金：天津市自然科学基金面上项目(22JCYBJC01370);山东省第三地质矿产勘查院科研项目(SYKJ-202203)联合资助。

摘　　要：胶东大疃刘家铍矿床位于华北板块东南缘,矿体受NW向断裂控制,圈定的7条矿体呈透镜状产出,赋存于中细粒正长岩中。矿石矿物主要为羟硅铍石,与绢云母、方解石、重晶石、褐铁矿等蚀变矿物密切共生。Be与Mo、Rb、Cs、REE等元素具有良好的正相关性,与CaO呈负相关关系,矿床成矿专属性明显。矿区内正长花岗岩为高硅、富碱、高钾、贫镁铁岩石,为准铝质-弱过铝质岩石;正长岩具有低硅、富碱、高钾特征,为准铝质岩石。两类岩石均具有轻重稀土分馏明显,轻稀土富集,无明显负Eu异常的稀土元素特征,稀土及微量元素配分模式相同,微量元素具有富集大离子亲石元素,亏损Nb、Ta、Ti等高场强元素的特征。正长花岗岩锆石LA-ICP-MS U-Pb定年表明其侵位于200.3±1.3Ma,全岩Sr-Nd同位素组成比较均一,ε_(Nd)(t)值为-15.8~-15.4,Hf同位素组成变化范围较大,ε_(Hf)(t)为-25.5~-7.75;正长岩锆石LA-ICP-MS U-Pb定年表明其侵位于200.9±1.4Ma,ε_(Hf)(t)值为-23.2~-15.7。地球化学研究指示正长岩为经历了华南陆壳交代的华北富集岩石圈地幔低程度部分熔融的产物,正长花岗岩来源于俯冲的华南陆壳,二者为华南板块与华北板块碰撞折返阶段岩浆作用的产物。The Datuanliujia is a Be deposit,which is hosted in the medium-fine grain syenite on the southeastern margin of the North China Block.The deposit is controlled by NW fault and contains 7 orebodies with lenticular shapes.The ore mineral is bertrandite,which is associated with sericite,calcite,barite and limonite.The deposit has obvious metallogenic specialization,and Be,Mo,Rb,Cs,REE elements have a good positive correlation,but a negative correlation with CaO.The syenogranite have high SiO_(2),and alkalis,but low magnesium and iron,belong to metaluminous-weakly peraluminous series.The syenite have high alkalis,but low SiO_(2),belong to metaluminous series.All rocks are obvious light and heavy rare earth fractionation,light rare earth enriched,and no obvious negative Eu anomaly.Trace elements show LILEs enriched,negative Nb,Ta,and Ti anomalies,depleted in HFSEs,and possess of the same partition pattern for rare earth and trace elements.Zircon LA-ICP-MS U-Pb dating gives the emplacement age of 200.3±1.3Ma for syenogranite.Theε_(Nd)(t)values varying from-15.8 to-15.4 for the syenogranite,but in-situ analyses of zircons show that the syenogranites have heterogeneous Hf isotopic compositions andε_(Hf)(t)varying from-25.5 to-7.5.Zircon LA-ICP-MS U-Pb dating gives the emplacement age of 200.9±1.4Ma for syenite.The in-situ analyses of zircons show that the syeniteε_(Hf)(t)varying from-23.2 to-15.7.The geochemical studies indicated that syenite are derived from partial melting of the enriched lithospheric mantle of North China Block which undergone continental crust metasomatism in South China Block,syenogranite are derived from subducted continental crust of South China Block.Both of them are formed in the stage of exhumation.

关 键 词：地球化学 矿床地质 LA-ICP-MS锆石U-PB定年 SR-ND-HF同位素 大疃刘家铍矿床 胶东 

分 类 号：P588.15[天文地球—岩石学] P597.3[天文地球—地质学] P618.72