摘要
近年来,利用黄铁矿微量元素揭示金矿成矿作用已取得了重要进展。对华北克拉通南缘熊耳山地区上宫造山型金矿开展黄铁矿结构特征与微量元素研究,探讨Au的赋存状态和沉淀机制。上宫金矿受区域NE向断裂系统控制,成矿过程可分为4个阶段:石英—粗粒黄铁矿阶段、烟灰色石英—细粒黄铁矿阶段、乳白色石英—方解石—多金属硫化物阶段和石英—方解石—萤石—黄铁矿阶段,金矿化主要发生在第二、三阶段。矿相学观察和黄铁矿微量元素特征表明,Au主要以不可见金形式赋存于黄铁矿中,仅第三阶段发育少量可见金。第二阶段黄铁矿发育复杂的核—幔—边结构,核部和幔部内侧环带是溶蚀的产物,幔部黄铁矿的微量元素体现两类不同特征:第一类幔部黄铁矿的Pb、Se、Tl含量最高,As、Te、Au、Ag、Sb含量较高,结合第三阶段可见金与碲铅矿、碲金矿共生的现象,指示低熔点亲铜元素熔体在Au的迁移和沉淀过程中起到重要作用;第二类幔部黄铁矿的Au、As、Te、Ag含量最高,Tl、Sb含量较低,As/Sb、Ag/Co比值较高,Tl/Cu比值较低,指示流体沸腾可能是导致Au沉淀的机制。第二、三阶段绝大部分黄铁矿Co、Ni含量变化范围很大,但Co/Ni比值恒定,支持水岩反应与流体沸腾一样,也是导致Au沉淀的机制。
Great progress about gold mineralization has been made recently by using pyrite trace elements.Textures and trace elements of pyrite from the Shanggong orogenic gold deposit in the Xiong'ershan were used to discuss gold occurrence and precipitation in this study.The Shanggong gold deposit is controlled by NE-trending faults and includes four stages of quartz-coarse-grained pyrite,quartz-fine-grained pyrite,quartz-calcite-sulfides,and quartz-calcite-fluorite-pyrite stages with gold mineralization in the second and third stages.Ore petrography and pyrite trace elements suggest that most gold is invisible in pyrite and minor amounts of visible gold is in the third stage.Pyrite of the second stage shows complex core-mantle-rim zoned texture.Resorbed cores and As-rich mantles represent a corrosion product.The mantles of zoned pyrite have two types according to trace element compositions.The first has the highest Pb,Se,and Tl and high As,Te,Au,Ag,and Sb abundances,indicating that the melts of low-melting point chalcophile elements play an important role for gold mobilization and precipitation combined with visible gold occurred with altaite and calaverite in the third stage.The second displays the highst Au,As,Te,and Ag but low Tl and Sb contents with high As/Sb and Ag/Co and low Tl/Cu values,suggesting fluid boiling.Pyrite in the second and third stages has large ranges of Co and Ni contents with invariable Co/Ni values.These observations probably favors both fluid-rock interaction and fluid boiling for gold precipitation.
作者
郭祥清
Guo Xiangqing(Zijin Mining Group Co.,Ltd.,Xiamen 361008,China)
出处
《资源环境与工程》
2025年第6期675-684,共10页
Resources Environment & Engineering
关键词
华北克拉通
上宫金矿
黄铁矿
微量元素
水岩反应
流体沸腾
North China Craton
Shanggong gold deposit
pyrite
trace element
fluid-rock interaction
fluid boiling
