云南个旧芦塘坝—阿西寨地区深部矿化的浅部表征:构造蚀变与原生晕指示

Surface Indicators for Deep Mineralization in the Lutangba-Axizhai Area of Gejiu,Yunnan Province:Implications from Tectonic Alteration and Primary Geochemical Halos

层间氧化矿是个旧高松矿田重要的锡矿化类型。加强该类型矿化的研究与勘探工作有望成为缓解老矿山资源危机、提升矿产储量的有效手段之一。本文选择具有层间氧化矿良好成矿条件的芦塘坝—阿西寨地区为研究区,开展地表构造蚀变和原生晕地球化学研究,为该地区层间氧化矿的勘查提供新的依据。野外地质调查表明,研究区地表矿化蚀变明显受断裂控制,特别是NE向断裂与EW向断裂交汇部位蚀变强烈,主要由铁泥质蚀变和方解石脉构成。蚀变岩及围岩中13种关键元素组合分析揭示Cd、As、Sb、Pb和Zn对寻找Sn矿体有良好的指示意义。根据地表原生晕地球化学综合异常分布,结合构造蚀变带特征,圈定出Ⅰ至Ⅳ4个成矿靶区。通过对比分析各靶区原生晕的前缘晕、近矿晕和尾晕的元素组合特征,推测Ⅰ和Ⅱ号靶区深部层间氧化矿找矿潜力较好;Ⅲ号靶区地表氧化矿已被剥蚀,但深部有可能存在硫化矿;Ⅳ号靶区深部可能有少量剩余的未被剥蚀的氧化Sn矿体。

Interlayer oxidized tin ore is a significant mineralization type in the Gaosong orefield at Gejiu.Enhancing the study and exploration for this type of tin mineralization is important to relieve resource crisis and increase the reserve for exhausting mines.We study the surface tectonic alteration and primary geochemical halo in the Lutangba-Axizhai area which shows beneficial mineralization conditions for interlayer oxidized deposits,to provide a new basis for their exploration.Field geological survey exhabits that the surface mineralization/alteration is mainly composed of iron alteration,argillization and calcite veins.It is commonly controlled by faults,especially at the intersection of NE-and EW-trending ones.The integrated analysis of 13 key elements in the altered rocks and wallrocks suggests that Cd,As,Sb,Pb and Zn are potential indicators for Sn orebody.The integrated anomaly distribution of primary geochemical halos in combination with the characteristics of structural alteration zones delineate four metallogenic target zones(ⅠtoⅣ).Comparation and analysis on the front-,near-and rear-halo element combination characteristics of primary geochemical halos in each target area shows that target zoneⅠandⅡseem to have deep interlayer oxidized tin ore prospecting potential;target zoneⅢwith the oxidized ore is probably eroded on the surface,and have deep sulfide ore potential;target zoneⅣlikely has small amount of uneroded remnant orebodies at depth.