胶西北花山岩体岩石成因与地质意义:来自地球化学、年代学与Sr-Nd同位素的约束  

Petrogenesis and Geological Significance of Huashan Pluton in Northwestern Jiaodong:Constraints from Geochemistry,Chronology and Sr-Nd Isotopes

作　　者：迟乃杰 单伟 张晨西 赵艳 高华丽[3] 郭广军 马祥县 孙雨沁 李敏 王秀凤 CHI Naijie;SHAN Wei;ZHANG Chenxi;ZHAO Yan;GAO Huali;GUO Guangjun;MA Xiangxian;SUN Yuqin;LI Min;WANG Xiufeng(Shandong Institute of Geological Sciences,Key Laboratory of Gold Mineralization Processes and Resource Utilization,MNR,Shandong Provincial Key Laboratory of Metallogenic Geological Process and Resource Utilization,Shandong Ji'nan 250013,China;Zoucheng Bureau of Natural Resources and Planning,Shandong Ji'ning 250000,China;Shandong Institute of Geological Surveying,Shandong Ji'nan 250013,China)

机构地区：[1]山东省地质科学研究院,自然资源部金矿成矿过程与资源利用重点实验室,山东省金属矿产成矿地质过程与资源利用重点实验室,山东济南250013 [2]邹城市自然资源与规划局,山东济宁250000 [3]山东省地质调查院,山东济南250013

出　　处：《山东国土资源》2023年第10期1-11,共11页Shandong Land and Resources

基　　金：国家自然科学基金项目(编号:42272104,42272122,42172094);山东省地质勘查项目(鲁勘字[2020]7号、鲁勘字[2022]12号);省部级重点实验室开放课题(kfkt201810)联合资助。

摘　　要：胶东金矿成矿作用独具特色,是世界第三大金矿区。关于金的来源等问题一直是地学研究热点,与金成矿具有时空关系的同期岩浆岩的成因研究是金来源研究中的重要方向。本文选择焦家金矿带南端的伟德山期花山隐伏岩体为研究对象,首次系统开展了岩相学、地球化学及LA-MC-ICP-MS锆石U-Pb年代学及Sr-Nd同位素研究。结果表明:花山岩体岩性主要为二长花岗岩,为高钾钙碱性系列过铝质花岗岩,具有轻稀土富集、重稀土元素亏损、铕负异常的特征,其化学特征与同期的周官岩体具有一定的差异,表现出同时期的多批次岩浆脉冲的特征;LA-MC-ICP-MS的U-Pb年龄为(118.07±0.52)Ma,可以代表岩体结晶年龄。岩体^(87)Sr/^(86)Sr值为0.712189,表明其有幔源物质的参与;而(^(87)Sr/^(86)Sr)i为0.709729,ε_(Nd)(t)的值为-20.63,亏损地幔模式年龄(t_(DM2))为3808Ma,显示其有新太古代胶东岩群基底的参与;花山岩体为壳幔混合成因,即早先幔源岩浆底侵,与下地壳胶东岩群熔融形成的岩浆发生混合,形成年轻的中酸性岩浆;岩浆继续上侵,受到玲珑期花岗岩的同化混染而形成。Jiaodong gold deposit area is the third largest gold deposit area in the world.The origin of gold has always been a hot topic in geoscience.The study of the genesis of contemporaneous magmatic rocks with spatiotemporal relationships with gold mineralization is an important direction in the study of gold sources.In this paper,selecting Huashan concealed rock mass in Weideshan period in southern Jiaojia gold deposit as the research object,petrography,Geochemistry and LA-MC-ICP-MS zircon U-Pb chronology and Sr-Nd Isotope studies has been carried out systematically for the first time.It is showed that the lithology of Huashan rock mass is mainly composed of monzogranite,a high potassium calcium alkaline series of peraluminous granite,characterized by light rare earth enrichment,heavy rare earth element depletion,and europium negative anomaly.Its chemical characteristics are somewhat different from those of Zhouguan rock mass during the same period,with the characteristics of multiple batches of magma pulses during the same period.The U-Pb age of LA-MC-ICP-MS is(118.07±0.52)Ma,which can represent the crystallization age of the rock mass.The Sr value of the rock mass is 0.712189,indicating the involvement of mantle derived materials;And(^(87)Sr/^(86)Sr)i is 0.709729.The value of ε_(Nd)(t)is-20.63,and the depleted mantle model age(t_(DM2))is 3808 Ma,indicating the involvement of the basement of Neoarchean Jiaodong group.The Huashan rock mass is of crust mantle mixing origin,which means that the mantle derived magma was initially subducted and mixed with the magma formed by the melting of the Jiaodong rock group in the lower crust,forming young intermediate acidic magma.The magma continued to invade and was formed by assimilation and contamination of Linglong period granite.

关 键 词：花山岩体 岩石成因 锆石U-PB SR-ND同位素 胶西北 

分 类 号：P545[天文地球—构造地质学]