俄罗斯堪察加中部Baranevskoy金-银矿床矿物学与流体包裹体研究  

Mineralogy and fluid inclusions study of the Baranevskoye gold-silver deposit,central Kamchatka,Russia

作　　者：Victor M.Okrugin Elena D.SKilskaia 

机构地区：[1]Institute of Volcanology and Seismology,Far Eastern Branch of Russian Academy of Sciences,Piip Boulevard,9,Petropavlovsk-Kamchatsky 683006,Russia

出　　处：《地学前缘》2020年第5期136-150,共15页Earth Science Frontiers

基　　金：The Japanese Government Scholarship(MEXT);The Russian Academy Foundation(Grant 12-05-31369);Far East Ressian Research(Grants 12-Ⅲ-B-08-168,13-Ⅲ-B-08-193,14-Ⅲ-B-08-192)。

摘　　要：Baranevskoy金-银矿床产于巴尔喀什火山的火山口,该火山坐落在堪察加中部矿区东南部。本文基于矿物学原理和流体包裹体数据分析探讨了Baranevskoy金-银矿床的成矿环境及其物理化学条件。Baranevskoy金-银矿床的围岩为中新世—上新世的安山岩和玄武岩。热液蚀变活动随深度逐渐变化,从而可以进一步划分出最深部的石英带、中部的石英-绢云母(明矾石)-黄铁矿-铁钛氧化物带及其伴生的石英-绢云母-伊利石-黄铁矿矿物组合和浅部的石英-冰长石-水云母-黏土矿物-碳酸盐岩带。成矿早期存在密集浸染的铜矿化,主要矿石矿物有黄铜矿、斑铜矿、砷黝铜矿-黝铜矿,并在Rhzavaya矿脉中存在少量的自然金。其中砷黝铜矿-黝铜矿系列以砷黝铜矿和黝铜矿两个端员作为代表,且以黝铜矿为主。成矿后期产出代表晚期金-银矿化的自然金、黄铁矿、黄铜矿、闪锌矿、方铅矿、碲化物和硫酸盐等标志性矿物。早期铜矿化(第一期)被认为是中硫阶段,紧随其后的为低硫型金-银矿化(第二期和第三期)。金从第一期到第三期都有沉淀。经研究发现,自然金也赋存于变质围岩的岩石裂隙内。早期的自然金相对富银,其中金的摩尔分数为59%~65%,低于后期(第二、第三期)自然金中金的摩尔分数(64%~72%)。流体包裹体显微测温结果显示,位于中部(Central)矿脉的包裹体均一温度为190~280℃,Rzhavaya矿脉的包裹体为190~240℃,产出自然金的蚀变围岩中石英的包裹体温度为230~310℃。包裹体总体表现出低盐度(0.9%~2.4%NaCleq)特征,推测存在大气水的混入。The Baranevskoye gold-silver deposit occurs within the caldera of the Balkhach volcano in the south-east part of the Central Kamchatka mining district.The host rocks are andesite,basalt of MiocenePliocene age.The hydrothermal alteration varies as a function of depth and is subdivided into deepest quartize zone,intermediate zones of quartz-sericite(alunite)-pyrite-Fe-Ti-oxides and quartz-sericite-illitepyrite associations,and shallow quartz-adularia-hydromica-clay-carbonate zone.Mineralogical study reveals three major stages of mineralization.The early stage is present by a highly disseminated copper-rich mineralization with main ore minerals of chalcopyrite,bornite,tennantite-tetrahedrite,and rare gold occurring in the Rzhavaya vein.Tennantite-tetrahedrite series is represented by two end-members of tennantite and tetrahedrite with tetrahedrite preponderating.Later stages are characterized by advanced AuAg mineralization containing gold,pyrite,chalcopyrite,sphalerite,galena,tellurides,and sulfosalts.The early Cu-rich mineralization(stageⅠ)is designated as an intermediated state,followed by later lowsulfidation Au-Ag mineralization(stagesⅡandⅢ).Gold was constantly deposited through from StageⅠto StageⅢ.Crystalline gold was also found in void-space in the altered host rocks.Early gold is relatively Agrich with Au content of about 59-65%compared to later gold of StageⅡandⅢ(Au 64-72%).Fluid inclusion microthermometry shows homogenization temperatures between 190-280℃for the Central vein,190-240℃for the Rzhavaya vein and 230-310℃for the quartz of the altered host rocks associated with crystalline gold.Low salinity of the fluid inclusions(0.9-2.4 wt.%NaCl eq.)suggests an influx of the meteoric waters.Based on mineralogical and fluid inclusions data the physicochemical conditions of the ore formation are discussed.

关 键 词：金 矿床 火山弧 斑铜矿 气液包裹体 堪察加 

分 类 号：P618.51[天文地球—矿床学] P618.52[天文地球—地质学]