陕西东光金矿床地质特征及金的富集规律

东光金矿床处于扬子板块北部被动大陆边缘的南秦岭印支期东西向褶皱带。金矿体受控于裂隙构造带,裂隙带充填石英脉可分为两期,早期石英脉不含矿,晚期含矿石英脉规模较小,沿早期石英脉内裂隙、石英脉壁和脉旁围岩的裂隙贯入。金矿物的赋存状态以裂隙金和粒间金为主,粒度粗大,几乎全为粗、巨粒。成矿过程初步划分为4个阶段:中粗粒自形黄铁矿-石英阶段、细粒他型黄铁矿-闪锌矿-金-石英阶段、细粒他型黄铁矿-方铅矿-金-石英阶段和细粒他型黄铁矿-黄铜矿-石英阶段,主成矿期为第二和第三阶段。金矿体赋存于泥盆系星红铺组绢云母千枚岩的构造裂隙带内,矿石的含金性与硫化物的多少及脉岩的破碎程度呈正相关关系,细粒他型黄铁矿化、方铅矿化、闪锌矿化及碳酸盐化、绿泥石化蚀变叠加部位金富集程度较高,在镜下可见各类金属硫化物交代作用明显,显示了多期热液叠加成矿的特点。

Geological Characteristics and Gold Enrichment Regularity Dongguang Gold Deposit in Shaanxi Province

Dongguang gold deposit is located in EW Indosinian foldbelt at the passive continental margin of the Northern Yangtze plate. The gold ore body is controlled by the fracture zone. The quartz veins which fill in the fractured zone can be divided into two phases, early quartz vein did not bear ore and the late stage of quartz vein is ore-bearing and small in scale. The late ore-bearing quartz veins penetrated in the fractures and fissure along the early quartz vein, quartz vein wall and surrounding rocks. The occurrence of gold deposits is dominated by fissure gold and intergranular gold, and almost are coarse and giant gold particles. The process of metallogenic process can be roughly divided into 4 stages:medium and coarse grained euhedral pyrite-quartz stage, granule allotype pyrite-sphalerite-gold-quartz stage, granule allotype pyrite-galena-gold-quartz stage and granule allotype pyrite-chalcopyrite-quartz stage. The main metallogenic period is the second and third stages. Gold deposits exist in structural fracture of Sericite phyllite in Devonian System. There is a positive correlation between the gold-bearing property of the ore & the content of sulfide and the crushing degree of the vein rock. The gold enrichment exists in the superposition areas of granule allotype pyrite mineralization, galena mineralization, sphalerite mineralization, carbonate mineralization and chloritization mineralization. The metasomatism of all kinds of metal sulfides is obvious under the microscope,showing that the characteristics of multiphase hydrothermal superimposed mineralization.