摘要
胶东是我国最重要的金矿集区,其中"焦家式"破碎带蚀变岩型金矿是区内最重要的金矿床类型。寺庄金矿床位于胶东金矿集区焦家金矿田南部,是典型的"焦家式"金矿,沿NE向焦家断裂发育大规模的热液蚀变带,金矿体均产于这些蚀变带内。热液蚀变空间分带明显,距离焦家断裂由近到远向下盘依次发育黄铁绢英岩化、绢英岩化、钾长石化蚀变带。时间上,钾长石化为成矿前蚀变,绢英岩化和黄铁绢英岩化叠加在钾长石化蚀变之上,为成矿期蚀变,伴随金矿化。质量平衡计算表明:钾长石化过程,主量元素SiO_2、Al_2O_3、Fe_2O_3、FeO、MgO、CaO、Na_2O、P_2O_5,成矿元素Au、Ag,亲铜元素As、Hg、Sb、Bi和稀土元素均从玲珑黑云母花岗岩中迁出;而K_2O、MnO和Cu从流体中迁入玲珑黑云母花岗岩。绢英岩化和黄铁绢英岩化过程元素迁移行为高度相似,主量元素SiO_2、Fe_2O_3、FeO、MgO、CaO、K_2O、MnO,成矿元素Au、Ag,亲铜元素As、Hg、Cu、Sb、Bi和轻稀土元素均从流体中迁入钾长石化花岗岩,而主量元素Al_2O_3、Na_2O和重稀土元素均从钾长石化花岗岩中迁出。二长石温度计估算钾长石化蚀变形成的温度约为392～449℃。玲珑黑云母花岗岩(δEu=1.45)和钾长石化花岗岩(δEu=1.38)具有明显的Eu正异常,绢英岩(δEu=0.97)和黄铁绢英岩(δEu=0.93)具有轻微的Eu负异常,指示钾长石化发生于相对氧化环境下,而绢英岩化和黄铁绢英岩化发生于相对还原环境下。综合分析表明,成矿前高温、氧化、碱性流体作用于玲珑黑云母花岗岩形成大范围面状钾长石化蚀变;成矿期中低温、还原、弱酸性的流体与钾长石化花岗岩发生水岩反应,形成绢英岩化和黄铁绢英岩化,在此过程中硫化作用引起金硫络合物分解,导致金沉淀富集成矿。
The "Jiaojia-type" gold deposit which is dominated by disseminated-and stockwork-style gold mineralization is the most significant gold deposit type in Jiaodong Peninsula which is the largest and the most important gold province in China.The Sizhuang gold deposit,located at the southern part of the Jiaojia goldfield in the northwestern Jiaodong Peninsula,is one of the most typical "Jiaojia-type" gold deposits.Hydrothermal alteration zones from the fresh granite to the ore-controlling Jiaojia Fault at the eposit include the distal K-feldspar alteration,intermedium sericite-quartz alteration and proximal pyrite-sericite-quartz alteration.Ore is hosted in the pyrite-sericite-quartz alteration and sericite-quartz alteration zone in the footwall of the Jiaojia Fault.The detailed geological observations in the field and under the microscope show that K-feldspar alteration occurred before the gold mineralization and sericite-quartz alteration and pyrite-sericite-quartz alteration which were companied by the gold mineralization partially overprinted the K-feldspar alteration.Mass-balance calculations indicate complex behaviors of different types of elements during fluid-rock interaction.SiO2,Al2 O3,Fe2 O3,FeO,MgO,CaO,Na2 O,P2 O5,Au,Ag,As,Hg,Sb,Bi and REEs were brought out from fresh Linglong biotite granite,while K2 O,MnO and Cu were brought in from fluid during the K-feldspar alteration.Behaviors of different elements during pyrite-sericite-quartz alteration and sericite-quartz alteration are highly similar.SiO2,Fe2 O3,FeO,MgO,CaO,K2 O,MnO,Au,Ag,As,Hg,Cu,Sb,Bi and LREE were brought in from fluid,while Al2 O3,Na2 O and HREE were brought out from the Kfeldspar altered granite.Studies on two-feldspar geo-thermometer reveal that the temperature of K-feldspar alteration ranges from 392℃to 449℃.Obvious Eu positive anomalies were found in the Linglong biotite granite(δEu = 1.45) and the K-feldspar altered granite(δEu =1.38),while weak Eu negative anomalies were found in sericite-quartz altered rocks(δEu =0.97) and pyrit
作者
刘向东
邓军
张良
林少一
周明岭
宋宇宙
徐晓磊
连琛芹
UU XiangDong;DENG Jun;ZHANG Liang;UN ShaoYi;ZHOU Mingling;SONG YuZhou;XU XiaoLei;UAN ChenQin(State Key Laboratory of Geological Process and Mineral Resources,China University of Geosciencesy Beijing 100083,China;No.6 Exploration Institute of Geology and Mineral Resources of Shandong Province,Weihai 264209,China;Jiaojia Gold Company,Shandong Gold Mining Stock Co.,Ltd.,Laizhou 261441,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2019年第5期1551-1565,共15页
Acta Petrologica Sinica
基金
国家重点研发计划项目(2016YFC0600107-4)
国家自然科学基金项目(41572069)
高等学校学科创新引智计划项目(B07011)联合资助
关键词
热液蚀变作用
质量平衡
二长石温度计
寺庄金矿床
胶东
Hydrothermal alteration
Mass balance
Two-feldspar geo-therm om eter
Sizhuang gold deposit
Jiaodong gold Province
