滇西北衙金多金属矿床成矿作用特征标志

摘要

This paper systematically summarizes the characteristic marks of metallogenesis in Beiya goldpolymetallic deposit.From interior to the outer contact of a porphy occur lenticular veins and parallel steep veins in fractural zone of fault.At the contact Skarn rings the porphyry and Au-Fe-Cu bodies here occur continuously as big lenticular and tabular body in the skarn.In outer contact Au-Fe、Pb-Ag ore bodies occur in layeroid,lenticular bodies along interformatioanal fractural zone.In the distal zone Au-Fe ore bodies occur in small lenticular veins and steep parallel veins in the fractural zone of fault.Mineral assemblage,ore elements and alteration zoning are characterized by distribution from high temperature mineral and element to the low and the skarn ore deposit.Mineralization can be divided into early skarn-late skarn-magnetite-quartz+sulfides-carbonate stages.Fluid inclusion of all the stages are divided into fluid rich inclusion,gas rich inclusion,sub-crystal-bearing inclusion and fluid-gas-sub-crystal phased inclusion riched in CO2.The mineralization is dated at 36.46 Ma-39.44 Ma which is basically coincided with that of quartz syenite porphyry(35.00 Ma-36.72 Ma).The metallogenic depth is 0.7～2.2 km.This is a porphyry-skarn Au polymetallic deposit.The carbonatite of the Beiya Formation + multi-period faulting tectonic system(contact zone tectonic,interstratified crushed zones,fault fracture zone,unconformity interface) + emplacement of the rich-alkaline magma constituted metallogenic system and metallogenic model of trinity in the Beiya gold-polymetallic deposit.%文章通过对北衙金多金属矿床成矿作用特征标志的系统总结,认为从岩体内部到外接触带,矿化样式以“脉-块体-层-脉”的内外多元结构模式产出:岩体内部Au-Fe(Cu)矿体呈透镜状脉、平行脉沿断层破碎带陡倾斜产出;岩体接触带附近的矽卡岩带围绕岩体呈环状分布,Au-Fe-Cu矿体以大透镜状、块体状在矽卡岩带中断续产出;外带Au-Fe、Pb-Ag矿体呈似层状、透镜状,沿层间破碎带产出;远程带Au-Fe矿体呈小透镜状脉、平行脉沿断层破碎带陡倾斜产出.矿体对应的矿物组合、成矿元素和蚀变分带具有自高温到低温的分布规律和矽卡岩型矿床的特征.矿床的热液成矿作用阶段可划分为早矽卡岩、晚矽卡岩、磁铁矿、石英硫化物以及碳酸盐五个热液阶段,各阶段流体包裹体划分为富液相包裹体、富气相包裹体、含子晶矿物包裹体、富含CO2三相包裹体等四类.成矿年龄为36.46 Ma 39.44 Ma,与石英正长斑岩的成岩年龄35.00 Ma-36.72 Ma基本一致.矿床成矿深度范围为0.7～2.2 km.矿床类型为斑岩-矽卡岩型金多金属矿床.北衙组碳酸盐岩(T2b)+多期断裂构造系统(接触带构造、岩性界面及层间破碎带、断裂裂隙、不整合面构造)+喜马拉雅期富碱斑岩侵位构成了“三位一体”的成矿系统和成矿模式.