Abstract

The gold deposits of the Bodaibo ore district are enclosed in a thick (several kilometers) sequence of Riphean–Vendian carbonaceous carbonate–terrigenous deposits. Gold is concentrated at several stratigraphic levels; the largest deposit in Russia, Sukhoi Log, and its counterpart, Golets Vysochaishii, are confined to terrigenous deposits of the Riphean Khomolkho Formation. The characteristic components of the Khomolkho Formation are lenticular interlayers and layered disseminations of pyrrhotite and pyrite with clearly pronounced lithological–stratigraphic control of their distribution. The Golets Vysochaishii deposit is confined to the largest thickening of sulfide layers in carbonaceous chlorite–quartz–sericite phyllite schists of the lower part of the Khomolkho Formation. The sulfide content in the ore-bearing sequence is 5 wt %; native gold is enclosed in sulfide layers. According to the data of previous researchers, based on the distribution patterns of sulfur isotopes, sulfide ore-bearing deposits of the deposit were formed by hydrothermal–sedimentary pathways. The primary gold content of sulfide sediments is assumed in analogy with the neighboring Sukhoi Log and Verna deposits. The distribution of Au, As, Ag, and carbonaceous matter in the sulfide-bearing strata of the Golets Vysochaishii deposit is substratal, reflecting their accumulation during sedimentation. The rocks were metamorphically altered under the greenschist facies conditions, during which they recrystallized and sulfides and gold were redistributed with the rocks retaining their layered structure. There are no significant differences in the contents of the rock-forming components between the ore deposit and host rocks, which indicates the absence of metasomatic alteration in rocks associated with ore formation. Metamorphic processes at the deposits of the Khomolkho Formation were accompanied by replacement of ilmenite by rutile and pyrrhotite by pyrite, as well as a change in the composition of chlorites and carbonates with increasing iron content; these processes were regulated by the fugacity of oxygen and carbon dioxide. Metamorphic alteration, based fluid inclusion study data, took place in the temperature range 230–510°C with the participation of oxidized carbon dioxide–aqueous fluids (CO₂/CH₄ up to 17) with a salinity of 7–12 wt % equiv. NaCl and reduced (CO₂/CH₄ < 0.3) methane–nitrogen fluids with a salinity of 11–13 wt % equiv. NaCl.

中文翻译：

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Golets Vysoschaishii金矿黑页岩矿床形成特征（博代博矿区）

摘要

博代博矿区的金矿床被一个厚（数公里）的Riphean-Vendian碳质碳酸盐-陆源矿床层序包围。黄金集中在几个地层水平；俄罗斯最大的矿床 Sukhoi Log 及其对应物 Golets Vysochaishii 仅限于 Riphean Khomolkho 组的陆源矿床。Khomolkho 组的特征成分是透镜状夹层和磁黄铁矿和黄铁矿的层状分布，其分布具有明显的岩性-地层控制。Golets Vysochaishii 矿床仅限于 Khomolkho 组下部碳质绿泥石-石英-绢云母千枚岩片岩中最大的硫化物层增厚。含矿层序中硫化物含量为5wt%；天然金被包裹在硫化物层中。根据以往研究人员的资料，根据硫同位素的分布规律，该矿床的硫化物矿床是通过热液-沉积途径形成的。硫化物沉积物的原生金含量假设与邻近的 Sukhoi Log 和 Verna 矿床类似。Golets Vysochaishii 矿床含硫化物地层中的Au、As、Ag 和碳质物质的分布是地层的，反映了它们在沉积过程中的积累。岩石在绿片岩相条件下发生变质变质，在此期间它们重结晶，硫化物和金重新分布，岩石保持层状结构。矿床与母岩的成岩组分含量无显着差异，表明与成矿相关的岩石不存在交代蚀变。在 Khomolkho 组矿床的变质过程中，钛铁矿被金红石取代，磁黄铁矿被黄铁矿取代，并且随着铁含量的增加，绿泥石和碳酸盐的成分发生了变化；这些过程受氧气和二氧化碳逸度的调节。基于流体包裹体研究数据的变质蚀变发生在 230-510°C 的温度范围内，氧化的二氧化碳-水性流体（CO 在 Khomolkho 组矿床的变质过程中，钛铁矿被金红石取代，磁黄铁矿被黄铁矿取代，并且随着铁含量的增加，绿泥石和碳酸盐的成分发生了变化；这些过程受氧气和二氧化碳逸度的调节。基于流体包裹体研究数据的变质变化发生在温度为230-510°C的范围内，其中氧化了二氧化碳-水（CO 在 Khomolkho 组矿床的变质过程中，钛铁矿被金红石取代，磁黄铁矿被黄铁矿取代，并且随着铁含量的增加，绿泥石和碳酸盐的成分发生了变化；这些过程受氧气和二氧化碳逸度的调节。基于流体包裹体研究数据的变质蚀变发生在 230-510°C 的温度范围内，氧化的二氧化碳-水性流体（CO₂ /CH ₄至 17)，盐度为 7–12 wt % 当量。NaCl 和还原 (CO ₂ /CH ₄ < 0.3) 甲烷-氮流体，盐度为 11-13 wt % 当量。氯化钠。