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A. E. Melnik
A. E. Melnik
student
Saint Petersburg State Mining Institute (Technical University)
student
Saint Petersburg State Mining Institute (Technical University)

Articles

Geology
  • Date submitted
    2017-09-02
  • Date accepted
    2017-11-22
  • Date published
    2018-02-25

Age and metamorphic conditions of the granulites from Capral-Jegessky synclinoria, Anabar shield

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The paper presents the results of the isotope, geochemical and thermobarometric study of plagio-crystalline schist containing in the Upper Anabar series of the Anabar Shield. Granulite complexes of the paleoplatforms are the most important issue in addressing the fundamental problem of the Earth's crust origin and its composition. The early stages of crust formation which correspond to the deeply metamorphosed rocks of the platform basements, available for study within the shields, are of particular interest. The study of the age and metamorphic conditions of granulites by the case of the Upper Ananbar series allows specifying the stages the Anabar Shield's ancient crust formation. Isotope-geochemical (U-Pb geochronology for zircon and Sm-Nd for garnet-amphibole-WR) and thermoba-rometric (Theriak-Domino) studies of plagio-crystalline schist allowed to identify two Paleoproterozoic metamorphism stages within the territory of the Anabar Shield with an age of about 1997 and 1919 million years. The peak conditions of granulite metamorphism are determined as 775±35 С and 7.5±0.7 kbar, the parameters of the regressive stage are 700  C and 7 kbar. The sequence of the rocks metamorphic transformations can be assumed: high-thermal metamorphism of the granulite facies (T ≤ 810  C) and subsequent sub-isobaric (about 7 kbar) cooling to 700  C with a water activity increase and formation of Grt-Amp paragenesis corresponding to the transition from the granulite to amphibolite facies. Data on the REE and other trace elements distribution in zircon and rock-forming minerals obtained by the ion microprobe analysis contribute significantly to the isotope-geochemical data interpretation. 

How to cite: Sergeeva L.Y., Berezin A.V., Gusev N.I., Skublov S.G., Melnik A.E. Age and metamorphic conditions of the granulites from Capral-Jegessky synclinoria, Anabar shield // Journal of Mining Institute. 2018. Vol. 229. p. 13. DOI: 10.25515/PMI.2018.1.13
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
Geology
  • Date submitted
    2009-08-26
  • Date accepted
    2009-10-27
  • Date published
    2010-02-01

Scheelites of Gavrilovskoe deposit (first find)

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The Gavrilovskoe deposit (deposit of building stone) is situated in Vyborg district, Leningrad region. There was found scheelite (CaWO 4 ) in the «Northern» quarry at the Gavrilovskoe deposit in 2008. This mineral was identified exactly in the Saint Petersburg State Mining Institute (Technical University) with Raman Spectrometer Renishaw InVia Reflex. It was for the first time that scheelite was found at this place. There was researched a form of one scheelite crystal. The simple forms of this scheelite crystal were detected. It is very interesting to compare simple forms of scheelite from the Gavrilovskoe deposit to different crystals of this mineral, described in any science literature.

How to cite: Melnik A.E. Scheelites of Gavrilovskoe deposit (first find) // Journal of Mining Institute. 2010. Vol. 186. p. 31-33.