冀北小扣花营银矿床地质特征及成矿远景

Geological characteristics and metallogenic prospect of Xiaokouhuaying silver deposit in north Hebei province

冀北小扣花营银矿床赋存于侏罗统张家口组二、三段的火山碎屑岩、火山碎屑熔岩。银矿体严格受NW向构造破碎带控制,形状受剪裂构造的变化制约,多呈"S"状延伸。通过硫同位素样品测试,32S/34S变化范围为22.282~22.384,δ34S变化范围为-2.79‰^-7.32‰,证明矿液来自低温火山热液。经样品测温,辉银矿、方铅矿、闪锌矿等主要造矿矿物起爆温度240~330℃,说明矿物形成温度为中低温,且具有硅化、重晶石化、碳酸盐化等中低温围岩蚀变,为浅成中低温热液型银矿床。

Xiaokouhuaying silver deposit in north Hebei province is hosted in the second and third member of Zhangjiakou formation of Jurassic Series, which mainly consist of pyroclastic rocks and lavas. The silver orebodies deposits are strictly controlled by NW-strike structural fracture zone, which mainly extend as S-shape controlled by shear fractures. The sulfur isotope composition（32 S/34 S） of the silver ores is in the range of 22.282~22.384 and the range ofδ34 S is-2.79‰ to-7.32‰, wich prove that ore fluids are from low temperature volcanic hydrothermal solution. The decrepitation temperatures of the main ore-forming minerals such as argentite, galena, sphalerite are 240℃ to 330℃. Besides there are middle-low temperature wall rock alterations such as silicification, barite mineralization and carbonation in the deposit. So we consider that Xiaokouhuaying is a medium-low temperature hydrothermal type silver deposit