地学前缘 ›› 2020, Vol. 27 ›› Issue (5): 136-150.DOI: 10.13745/j.esf.sf.2020.5.58

• 地质过程与成矿作用示踪的成因矿物学 • 上一篇    下一篇

俄罗斯堪察加中部Baranevskoy金银矿床矿物学与流体包裹体研究

Victor M. OKRUGIN, Elena D. SKILSKAIA   

  1. SkilskaiaInstitute of Volcanology and Seismology, Far Eastern Branch of Russian Academy of Sciences, Piip Boulevard, 9, Petropavlovsk-Kamchatsky 683006, Russia
  • 收稿日期:2020-03-11 修回日期:2020-06-02 出版日期:2020-09-25 发布日期:2020-09-25

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

Victor M. OKRUGIN, Elena D. SKILSKAIA   

  1. SkilskaiaInstitute of Volcanology and Seismology, Far Eastern Branch of Russian Academy of Sciences, Piip Boulevard, 9, Petropavlovsk-Kamchatsky 683006, Russia
  • Received:2020-03-11 Revised:2020-06-02 Online:2020-09-25 Published:2020-09-25
  • About author:wideworldscience@gmail.com
  • Supported by:

    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。

关键词: 金, 矿床, 火山弧, 斑铜矿, 气液包裹体, 堪察加

Abstract:

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 Miocene-Pliocene 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-illite-pyrite 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 Au-Ag mineralization containing gold, pyrite, chalcopyrite, sphalerite, galena, tellurides, and sulfosalts. The early Cu-rich mineralization (stage I) is designated as an intermediated state, followed by later low-sulfidation Au-Ag mineralization (stages II and III). Gold was constantly deposited through from Stage I to Stage III. Crystalline gold was also found in void-space in the altered host rocks. Early gold is relatively Ag-rich with Au content of about 59%-65% compared to later gold of Stage II and III (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.

Key words: gold, ore deposit, volcanic arc, bornite, fluid inclusion, Kamchatka

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