Isotopic composition of carbon and oxygen in Chertovo Koryto gold ore deposit (Patomskoe Upland)

Isotopic compositionof carbon, oxygenised in carbonates and deoxidated in kerogen, as well as oxygen of the Chertovo Koryto gold deposit has been studied;the deposit was formed in the early-Proterozoic black-shale series. The isotopic composition of carbon in kerogen has meaning - 26.2and - 24.6‰. The ankerite from beresite and quartz veins characterised weighted mean - 18.5…- 18.2‰ and - 18.4…- 17.4‰respectively. The isotope relations of oxygen ankerite keep within a narrow range ƒ18О (14.2…15.1‰). It is supposed that weighting ofisotope composition of carbon of carbonates is caused by the mixture of isotopically light carbon kerogen in the course of its oxidationwith isotopically heavy carbon, arriving in the system with metal-bearing fluids generated in the mantle reservoirs. A number of factstestify to the possibility of existence of deep fluids: confinedness of ore deposits to the upper wall of a deep fracture, which carries outore-control and fluid-supplying functions; presence of inter-mineral dolerite dikes; presence of contrasting anomalies of phemophileelements (P, Ti, Mg, Ca, Fe, Mn) in beresite nearly frame ore-control a deep break; affinity of isotope composition of sulphur earlymetasomatic and late (in quartz veins) sulphides of ores to the meteoric standard (+1,8 …+4,7‰). The similar facts are fixed in thedeposits localised in shale (Sukhoy Log, Muruntau, Charmitan, Kedrovsky, Sovetskoe, etc.) and crystal (Irokinda, Berikulsky, etc.)substance. Isotope ratios of carbon of hydrothermal carbonates close to the mantle marks (-4.5 ‰) in many mesothermal gold depositsare consistent with the conclusion of the operation of the underlying metal-bearing solutions in systems of mineralization. In theChertovo Koryto ankerite deposits carbon isotope ratios correspond to values intermediate between isotopically light carbon of kerogenand relatively heavy mantle carbon. Possibly, addition of carbon to the area of mineralization occurred with solutions as a part of deepcarbonic acid. The isotope of carbon increased from early ankerite of beresites to late ankerite of quartz veins and veinlets, which maybe due to partial mixture of deep oxidised carbon with deoxidised carbon of kerogen slates in the course of its oxidation accompanied byberesite bleaching. The isotope composition of ankerite oxygen is thus common in magmatic hydrothermal carbonates. In othermesothermal deposits, such as the Sukhoy Log, the effect of mixture is absent. In contrast to the Chertovo Koryto deposit the deficit ofbleached (excluding kerogen) beresites here shows the functioning of deoxidised solutions unable to oxidise the carbon of kerogen.

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