摘要
胶东矿集区是世界著名的金矿资源基地,截止2019年累计查明金资源储量达5000余吨,区内广泛分布的中生代花岗岩与金矿有着密切的时间、空间关系。前人利用高精度重磁、CSAMT等物探方法解译,认为焦家成矿带、招平成矿带深部可能有隐伏郭家岭期花岗岩存在。本文通过近几年勘查施工钻孔揭露的胶西北三条主要金成矿带隐伏郭家岭期花岗岩,表现为较高的Na2O+K2O(5.80%~11.27%)、Al2O3(14.01%~16.36%)含量,高的Sr含量(632×10^(-6)~1224×10^(-6))、Ba含量(1641×10^(-6)~3512×10^(-6))和高的Sr/Y比值(185~435),CaO(1.25%~2.44%)、TiO2(0.08%~0.23%)、MgO(0.17%~0.84%)、全Fe2O3(0.67%~1.94%)、Rb(46×10^(-6)~110×10^(-6)),属于高钾钙碱性-钙碱性系列。岩石的A/CNK为1.01~1.06,投点于弱过铝质区域。稀土配分模式为轻稀土富集,重稀土亏损的右倾模式,具有正铕异常,弱负铈异常。微量元素特征显示富集Ba、K、Rb、Sr、Pb等大离子亲石元素(LILE),亏损Ta、Nb、P、Ti等高场强元素(HSFE)。三山岛北部海域斑状中粒二长花岗岩和焦家金矿带斑状中粒二长花岗岩锆石SHRIMP U-Pb测年结果为126.10±1.00 Ma和127.59±0.85 Ma。岩浆锆石εHf(t)值为-27.94~-18.59,Hf同位素二阶段模式年龄tDM2为2.95~2.36 Ga(均值2.47 Ga),样品分布于球粒陨石演化线之下壳源区域,岩浆源区与郭家岭岩体落点一致。结合岩石地球化学认为,钻孔揭露的郭家岭期花岗岩既具有地壳物质来源特征,又有地幔物质的加入,是陆壳酸性岩浆与幔源基性岩浆混合作用的结果。通过已开展的钻探工程及脉岩提供的信息,认为胶西北三条主要控矿断裂带下盘有郭家岭期花岗岩存在,同时对胶西北三条主要控矿断裂带、栖霞一带、乳山市周围深部可能存在郭家岭期花岗岩范围进行推测。这对整个胶东地区郭家岭期花岗岩的分布格局有一个全新的认识,为进一步研究郭家岭期花岗岩与金矿成矿�
The Jiaodong ore concentration area is a globally famous gold resource base.By 2019,the total gold resource reserves had reached 5000 tons.The Mesozoic granite widely distributed in the area has a close temporal and spatial relationship with gold deposits.By using high-precision gravity and magnetic,CSAMT and other geophysical methods,the predecessors believe that there may be concealed Guojialing granite in the deep part of the Jiaojia and Zhaoping metallogenic belts.The concealed Guojialing granites in the three main gold metallogenic belts in Northwest Jiaodong revealed by drilling in recent years are characterized by high Na2O+K2O(5.80%~11.27%),Al2O3(14.01%~16.36%),high Sr content(632×10^(-6)~1224×10^(-6)),Ba content(1641×10^(-6)~3512×10^(-6)),high Sr/Y ratio(185~435),CaO(1.25%~2.44%)and TiO2(0.077%~23%),MgO(0.17%~0.84%),total Fe2O3(0.67%~1.94%),Rb(46×10^(-6)~110×10^(-6)),belonging to high potassium calc-alkaline series.The A/CNK of the rocks is generally 1.01~1.06,which is located in the weak peraluminous region.There are positive Eu anomalies and weak negative Ce anomalies.Trace elements are characterized by enrichment of LILE such as Ba,K,Rb,Sr and Pb,and depletion of HSFE such as Ta,Nb,P and Ti.Zircon SHRIMP U-Pb ages of the porphyry medium grained monzogranite in the northern Sanshandao and Jiaojia gold belt are 126.10±1.00 Ma and 127.59±0.85 Ma,respectively.The zirconεHf(t)values range from-27.94 to-18.59,and the two-stage Hf isotope model ages range from 2.95 Ga to 2.36 Ga(mean 2.47 Ga).The samples are distributed in the crust source area below the chondrite evolution line,and the magma source area is consistent with the fall point of the Guojialing pluton.Combined with petrochemistry,it is considered that the Guojialing granite exposed by drilling has the characteristics of both crustal material source and mantle material addition,which is the result of mixing of continental crust acidic magma and mantle derived basic magma.According to the information derived from the drilling projects and d
作者
于晓卫
王来明
任天龙
祝培刚
刘汉栋
张文
郭瑞朋
侯建华
王立功
YU Xiaowei;WANG Laiming;REN Tianlong;ZHU Peigang;LIU Handong;ZHANG Wen;GUO Ruipeng;HOU Jianhua;WANG Ligong(Shandong Institute of Geological Survey,Jinan,Shandong 250014,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2023年第2期417-432,共16页
Acta Geologica Sinica
基金
山东省地质勘查项目(编号鲁勘字[2018]19号)
山东省莱州-招远金矿整装勘查区综合研究项目(编号鲁勘字[2014]7号)
国家重点研发计划项目(编号2017YFC0601506)联合资助的成果。
