Features of Ore Formation of Epithermal Ag-Au Teploe Deposit (Northeast Russia)

The paper presents the results of studying the distribution of major, rare, and rare earth elements in the terrigenous rocks, wall-rock metasomatites, and ore zones of the orogenic Malo-Tarynsky gold deposit (Upper Kolyma folded area, Northeast Russia). Hydromicatization, carbonatization, sulfidization, and silicification played an important role in the formation of metasomatites and ore zones leding to different mobility of macroelements with a predominance of acidic low-temperature carbonic-calcium metasomatism. Increase in the proportion of quartz in wall-rock metasomatites and ore zones involved the loss of the most of the rock-forming elements: К, Na, Al, Fe, Mg, and Тi, and Ca and CO2 were supplied. The ores and metasomatites of the deposit are characterized by As-Au-Sb-W geochemical specialization with low Bi, Co, Ni, Cr, Cu, and Zn and high Li, Ag, Cd, and Sc concentrations. The distribution spectra of REE contents in modified rocks are similar to that of REE in Upper Triassic host rocks showing some tendency to decreasing their amount. The removal of rare earth elements during the formation of metasomatites and ores was established. The values of the Eu/Eu* (0.61–0.88) and Ce/Ce* (0.6–1.3) anomalies indicate slightly reducing conditions of the ore formation with a limited involvement of oxidized meteoric water.

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Base metal mineralization of the Kolyma terrain in Northeast Russia: Overview and genetic classification

LITOSFERA ◽

10.24930/1681-9004-2019-19-5-717-730 ◽

2019 ◽

Vol 19 (5) ◽

pp. 717-730

Author(s):

A. N. Glukhov

Keyword(s):

Porphyry Copper ◽

Copper Deposit ◽

Genetic Classification ◽

Northeast Russia ◽

Ore Formation ◽

Quartz Veins ◽

Cyclic Changes ◽

Academy Of Sciences ◽

Far Eastern ◽

Base Metal Mineralization

Research subject. The Prikolyma terrain located in the Northeastern part ofRussia constitutes a long-lived Precambrian thrust-faulted structure hosting numerous Cu, Pb and Zn deposits of different types.Materials and methods. The mineralization of the terrain was examined during a course of research and exploration works over the 2007–2012. The rock geochemistry was studied using ICP-OES analysis at the Stuart Geochemistry and Essay laboratory (Moscow). The microprobe analysis of minerals was carried out at the facilities of the Far Eastern Branch of the Russian Academy of Sciences (Magadan) using a Camebax X-ray microanalyzer. The isotopic ratios of sulphur in sulphides were measured using a Finnigan MAT 253 isotope mass spectrometer.Results. The porphyry-copper deposit Nevidimka is represented by skarns and sulphide-quartz stockworks embedded in porphyry granites. The vein deposits Opyt and Glukhoye constitute sulphide-carbonate-quartz veins, the composition of which corresponds to copper-polymetallic ores of the peripheral parts of the copper-porphyry formation. These deposits feature a similar geochemistry and composition of sulphides and sulphur isotopes, which is characteristic of the Riphean complexes of the Prikolyma terrain. The stratiform Pb-Zn veins Nadezhda-3 and Khaya enclosed in Proterozoic dolomites represent parallel-bedding disseminated sulphides. The composition of these ores indicates their diagenetic origin. Tne stratiform copper deposit Oroyok is embedded in Proterozoic shales and can be referred to sediment-hosted copper deposits of a transgressive type.Conclusions. The diversity of Cu-Pb-Zn mineralization types in the Prikolyma terrain is established to have resulted from multiple cyclic changes of the geodynamic ore formation regime. During each such cycle, syngenetic mineralization was followed first by epigenetic and then by vein mineralization. The mobile, thrust-faulted structure caused repeated rejuvenation of ores, which inherited the geochemical features of hosting rocks.

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