摘要
弗雷斯尼洛贱金属-银矿床由交代的柱状、席状和浸染状硫化物矿体,以及赋存于白垩纪海相沉积岩和火山岩中的脉状矿体组成。该矿床以石英二长岩岩株为中心呈带状分布,离岩株越近越富集贱金属,但Ag的含量却越亏损。靠近该岩株的围岩发生了硅化和钙质硅化蚀变作用,局部被硫化物交代。而脉状矿体的围岩由远及近依次呈现出钾化、绢英岩化、泥化和青磐岩化蚀变。柱状、席状矿体和深部矿脉中的石英和方解石均一温度范围为240~350℃,浅部矿脉中的石英、方解石和闪锌矿的温度范围为140~275℃。柱状、席状和脉状矿床中的S同位素分析显示,方铅矿δ34S值介于-4.1‰^-8.0‰之间,而闪锌矿介于-2.0‰^-5.0‰之间。S同位素差异的出现可能与成矿流体p H值的轻微变化或氧逸度的增加有关。
The Fresnillo base metal- silver ore deposit consists of replacement chimney and manto orebodies, disseminated sulfide orebodies, and vein orebodies hosted mainly in Cretaceous marine sedimentary and volcanic rocks. The deposit exhibits southeastward zoned distribution away from a small quartz monzonite stock, and shows increasing silver content and decreasing base metal values with the distance from the stock. Wall rocks adjacent to the stock exhibit silicification and calc-silicate alteration that have been partially replaced by the sulfide minerals. Wall rocks of the vein orebodies exhibit potassic, phyllic, argillic, and propylitic alteration with increasing distance from the orebodies. Homogenization temperatures of quartz, calcite and spharelite in chimney, manto, and deep vein orebodies range from 240℃ to 350℃, while their homogenization temperatures in shallow and distal vein orebodies are between140℃ and 275℃. Galena δ^34S values from all orebodies at Fresnillo vary between-4.1‰ and-8.0‰, while sphalerite δ^34S values range between-2.0‰ and-5.0‰. The contrasting δ^34S values between galena and sphalerite might have resulted from a slight variation in ore fluid p H（as indicated by the wall rock alteration assemblages） or by increased log fo2.
出处
《地质通报》
CAS
CSCD
北大核心
2015年第6期1057-1064,共8页
Geological Bulletin of China
基金
中国地质调查局项目(编号:1212010811029
1212011220911)
