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D. S. Ashikhmin
D. S. Ashikhmin
A.P.Karpinsky Russian Geological Research Institute
A.P.Karpinsky Russian Geological Research Institute

Articles

Geology
  • Date submitted
    2020-05-28
  • Date accepted
    2020-05-28
  • Date published
    2020-06-30

The age of mineralization of Mayskoe gold ore deposit (Central Chukotka): results of Re-Os isotopic dating

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The article presents the results of the sulfide mineralization dating of the Mayskoe gold ore deposit using the Re-Os isotope system and isochron age estimation method of 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. Isochrones 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. While arsenopyrite is most closely associated with gold mineralization, one of the arsenopyrite varieties corrodes framboidal pyrite of the pre-ore stage, has a maximum of the crust component in the osmium isotopic composition and forms a mixing line in the isochron diagram with an apparent formation age of 458 ± 18 Ma. 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.

How to cite: Artemiev D.S., Krymsky R.S., Belyatsky B.V., Ashikhmin D.S. The age of mineralization of Mayskoe gold ore deposit (Central Chukotka): results of Re-Os isotopic dating // Journal of Mining Institute. 2020. Vol. 243. p. 266-278. DOI: 10.31897/PMI.2020.3.266
Geology
  • Date submitted
    2019-05-02
  • Date accepted
    2019-07-25
  • Date published
    2019-10-27

Composition Heterogeneity of Xenoliths of Mantle Peridotites from Alkaline Basalts of the Sverre Volcano, the Svalbard Archipelago

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The article presents the results of a study of the composition of xenoliths of mantle peridotites (seven samples), collected from the Quaternary basalts of the Sverre volcano, the Svalbard archipelago. The presence of two big (more than 15 cm in diameter) xenoliths of spinel lherzolite allowed us to consider a change in their composition in the cen- tral, intermediate, and marginal parts of the samples. It is proposed to distinguish three types of xenoliths by the distribution of trace and rare earth elements. Enrich- ment of mantle peridotites with light rare earth elements, as well as high field strength (HFS)   and large-ion lithophile (LIL) elements, is presumably associated with mantle metasomatism.

How to cite: Skublov S.G., Ashikhmin D.S. Composition Heterogeneity of Xenoliths of Mantle Peridotites from Alkaline Basalts of the Sverre Volcano, the Svalbard Archipelago // Journal of Mining Institute. 2019. Vol. 239. p. 483. DOI: 10.31897/PMI.2019.5.483
Geology
  • Date submitted
    2017-05-11
  • Date accepted
    2017-07-12
  • Date published
    2017-10-25

Geochemistry of spinels from xenoliths of mantle lherzolites (sverre Volcano, spitsbergen Archipelago)

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The paper presents the results of a study (LA-ICP-MS method) of spinel from the collection of mantle xenoliths of lherzolites (seven xenoliths) selected in quaternary alkaline basalts of the Sverre volcano, the Spitsbergen archipelago. The study of two large (more than 15 cm in diameter) xenoliths made it possible to study changes in the composition of minerals in the central, intermediate, and marginal parts of the samples of chromium diopside spinel lherzolites. The sinusoidal character of the REE distribution in spinels, which indicates the manifestation of mantle metasomatism, is established. The results obtained for the first time on the trace-element composition for spinels from mantle xenoliths in alkaline basalts of the Spitsbergen archipelago are supplemented by data on the geochemistry of spinels of mantle origin published in the world literature.

How to cite: Ashikhmin D.S., Chen Y.-S., Skublov S.G., Melnik A.E. Geochemistry of spinels from xenoliths of mantle lherzolites (sverre Volcano, spitsbergen Archipelago) // Journal of Mining Institute. 2017. Vol. 227. p. 511. DOI: 10.25515/PMI.2017.5.511