What is it about?

The results of the sulfide mineralization dating of the Mayskoe gold ore deposit (Central Chukotka) using the Re-Os isotope system are discussed and isochron age method is applied to the main sulfide minerals: arsenopyrite, pyrite, and antimonite. The complex multistage formation of the studied sulfides, as well as the close intergrowths of genetically different mineral phases, did not allow obtaining a single rhenium-osmium isochron corresponding to the formation time of sulfide mineralization.

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Why is it important?

Isochrons for single minerals, collected from each sulfide sample, turned out to be the result of isotopically distinct components mixture (radiogenic crustal and non-radiogenic mantle) and do not make sense from the geochronological point of view. In terms of geology, the most significant result of the study is an age estimation of 128.8 ± 4.4 Ma, obtained for the sulfide mineralization of Mayskoe deposit using Re-Os isotope dating of single fractions of pyrite and antimonite of the ore mineralization stage.

Perspectives

The initial osmium isotopic composition of the studied sulfides indicates a mixed mantle-crust source of sulfide mineralization. The issue of simultaneous ore genesis and granitoid magmatism in the Mayskoe deposit remained unresolved (the age of granitoids according to the U-Pb zircon system is 108 Ma). However, a possible solution could be the further determination of the Re-Os isochron age of the ore mineralization sulphides from the single paragenesis of a specific sample containing both arsenopyrite and pyrite (+ antimonite) with gold.

Boris V Belyatsky
Karpinsky Geological Institute (VSEGEI)

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This page is a summary of: The age of mineralization of Mayskoe gold ore deposit (Central Chukotka): results of Re-Os isotopic dating, Journal of Mining Institute, June 2020, Saint-Petersburg Mining University,
DOI: 10.31897/pmi.2020.3.266.
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