甘肃滴水山金矿不同构造-岩相带岩石地球化学特征及构造控矿机理探讨

摘要

滴水山金矿床位于北祁连加里东褶皱带的西段,分布于北西西向剪切带内,通过野外实地观察和镜下鉴定、样品测试,对该剪切带内Au2矿体构造-岩相特征及其地球化学元素变化特征进行了研究,结果表明:①该剪切带存在2期变形,早期为由北向南斜冲的韧-脆性剪切变形,晚期为斜向下滑的脆性变形.②根据元素分析结果,Au元素含量从安山质晶屑凝灰岩带→糜棱岩化安山质晶屑凝灰岩带→蚀变碎裂岩带→金矿化蚀变碎裂岩带逐步增高.根据相关性分析,Au与Ag相关性最好,其次为Pb、Mo,与As、Hg相关性一般.研究认为,滴水山金矿床北西西向剪切带早期韧-脆性变形有利于成矿元素的活化迁移,为Au元素的运移和初步富集提供了通道,晚期脆性变形主要形成各种张裂隙和构造破碎带,由于构造体制发生转换,导致Au元素的再次富集形成金矿体.%Located at the western section of Calidonian Fold Belt in North Qilian Mountain,the Dishuishan gold deposit is distributed in NWW fault zone.The paper has studied the structurallithofacies characteristics and its geochemical elements variation of Au2 orebody through field survey and microscopic observation and sample testing.The result show that:①There are two periods of deformation occurred in this shear zone,the early deformation is the ductile-brittle shear deformation in the process of oblique thrust from north to south,and the late deformation is brittle deformation in the process of oblique slide.②According to the results of elemental analysis,the content of gold is gradually increased from andesitic crystal tuff facie zone→ mylonitize andesitic crystal tuff facie zone→ altered cataclastec rock facie zone→ gold mineralization altered cataclastic rock facie zone,and which is significantly enriched in quartz vein.Furthermore,according to the correlation analysis,Au and Ag correlation is best,which is followed by Pb,Mo and has general correlation with the As and Hg.Research suggests that early ductile-brittle deformation in NWW fault zone is advantageous to the activation migration of ore-forming elements and provides the place for the preliminary enrichment of gold;late brittle deformation was mainly formed various tension fissure and tectonic fracture zone,with the enrichment of gold element to form gold orebodies by the transition of tectonic regime.