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Analysis of the spatial relations of gold ore occurrences and the enclosing geological environment in the Chukotka Autonomous Okrug (ChAO) has shown that Au-quartz ore occurrences in turbidites are located predominantly in areas of the Early Cretaceous granitoid magmatism with the thick collision-type continental crust. The Cu-Au porphyry deposits are located in areas with complete development of Early Cretaceous magmatism within the outer zone of the Okhotsk-Chukchi volcanoplutonic belt (OChVB). The Au-Ag epithermal deposits are located in the areas of the Late Cretaceous granitoid magmatism within the inner and outer zones of the OChVB. The prospects of island-arc complexes for searching for Kuroku-type Au-bearing ore objects are available. [ABSTRACT FROM AUTHOR]

The first data on study of individual fluid inclusions in the Zhilnoye deposit have been obtained. It has been found that the gold-bearing quartz veins of the deposit were formed by heterogeneous hydrothermal fluids with low salt concentrations (0.2-3.6 wt% equiv. NaCl under intermediate temperature conditions of 246-350°C). The fluid pressure was 80-160 bar corresponding to 0.3-0.6 km depths of formation under hydrostatic conditions. The parameters of the mineral-forming fluids of the Zhilnoye deposit correspond to typical parameters of the fluids of epithermal deposits. [ABSTRACT FROM AUTHOR]

The Au mineralization of Alyarmaut Rise was formed from the ore-forming fluids of two types strongly differing in pressure. The first type of fluid is similar to fluids of the orogenic Au-quartz deposits in terms of the physicochemical parameters and composition. These fluids were formed at a high pressure from heterogeneous, carbon dioxide-aqueous fluids with a low salinity at a depth of 5-7 km. The second type of fluid, which is also heterogeneous, has a shallower origin with a wide range of salinity variation and a small amount of carbon dioxide. This type of fluid is similar to the fluids of epithermal deposits. The wide range of pressure variation characterizing the mineralization of the rise indicates the vertical displacement of the block of the host rocks followed by erosion. Judging by the presence the secondary halos of Au, Ag, As, Sb, Pb, Zn, and Cu in the Upper Paleozoic carbonate-terrigenous rocks of the Alyarmaut Rise, there are prospects to reveal sites with new epithermal Au-Ag mineralization, which are essential for the area and unusual for the Anyui-Chukotka Fold System. [ABSTRACT FROM AUTHOR]

Ores of epithermal Au-Ag deposits of the Okhotsk-Chukotka volcanoplutonic belt are characterized by enrichment in a wide spectrum of elements in relation to the average upper crustal values. The data obtained show that the host volcanic rocks are the most likely sources of minor elements and REEs for the fluids that formed epithermal Au-Ag deposits of the Okhotsk-Chukotka volcanoplutonic belt. [ABSTRACT FROM AUTHOR]

The results of studying fluid inclusions in the quartz of ore body no. 6 from the Sovinoye deposit developed by the underground mine workings at a depth of 80 m from the surface are considered. The investigations showed that the ore in the Sovinoye deposit was formed at average temperatures during several stages from weakly concentrated hydrotherms saturated with Na, Cl, Mg, and Fe ions. Such ore-forming conditions are typical of mezothermal gold-quartz veined deposits in the terrigeneous quartz-carbonate strata. The results of FI study by modern methods do not contradict the previously offered metamorphogenic-magmatogenic model of ore formation for the Sovinoye deposit. [ABSTRACT FROM AUTHOR]

The article presents a study on Kupol gold (Au)-silver (Ag) epithermal deposit for ore-forming fluid which is the largest deposit in Northeastern Russia located in the outer zone of the Okhotsk-Chukotka volcanogenic belt in Chukotka, Russia. A graph between temperature and concentration for ore-forming fluid of the Kupol and Dvoinoi deposits is also presented. It discusses the gold-silver vein zone, an important structural peculiarity of Kupol deposit which is controlled by thick and long dykes and sills of rhyolite. A table showing the results of the study of fluid inclusions in minerals of the Kupol and Dvoinoi deposits is also presented.