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Vol. 18 (2015 year), No. 3

Fedoseev S. V., Zakharova A. A.
Diversification of companies' activity of the Arctic fuel and energy complex

The analysis of diversification role in company's activity has been considered. Special attention has been paid to the levels of strategy for a diversified company of the fuel and energy complex

(in Russian, стр.6, fig. 3, tables. 2, ref 7, Adobe PDF, Adobe PDF 0 Kb)

Vol. 24 (2021 year), No. 2, DOI: 10.21443/1560-9278-2021-24-2

Voytekhovsky Y. L. , Zakharova A. A.
Petrographic structures: Khibiny ijolites and urtites

In addition to the standard description of the structures and textures of crystalline rocks the mathematical approaches have been proposed based on a rigorous determination of the petrographic structure through the probabilities of binary intergrain contacts. In general, the petrographic structure is defined as an invariant aspect of rock organization, algebraically expressed by the canonical diagonal form of the symmetric Pij matrix and geometrically visualized by structural indicatrices – surfaces of the 2nd order. The agreed nomenclature of possible petrographic structures for an n-mineral rock is simple: the symbol Snm means that there are exactly m positive numbers in the canonical diagonal form of the Pij matrix. New types of barycentric diagrams have been proposed. To describe the massive texture, the concept of Hardy – Weinberg equilibrium has been proposed. This boundary classifies barycentric diagrams into areas within which canonical types of Рij matrices and topological types of structural indicatrices are preserved. The change in the organization of the rock within a type is quantitative, the transition from one type to another means structural restructuring. The methods are used to describe ijolites and urtites of the Khibiny massif, the Kola Peninsula. In the modern taxonomy of rocks, the boundaries between them are mostly conditional and are drawn according to the contents of rock-forming minerals, for example, between ijolites and urtites – according to the contents of nepheline and pyroxene. The strict definition of the petrographic structure proposed by the authors makes it possible to introduce into petrography the constitutional principle (structure + composition), which is successfully acting in mineralogy.

(in Russian, стр.7, fig. 4, tables. 0, ref 14, AdobePDF, AdobePDF 0 Kb)

Vol. 25 (2022 year), No. 1, DOI: 10.21443/1560-9278-2022-25-1

Zakharova A. A., Voytekhovsky Yu. L., Kompanchenko A. A., Neradovsky Yu. N.
Methodology for determination of petrographic structures using the MIU-5M device

The authors develop a statistical method for determining the structures of rocks. A mathematically rigorous definition of the petrographic structure through the probabilities of binary intergranular contacts is proposed. The petrographic structure is defined as an invariant aspect of rock organization algebraically expressed by the canonical diagonal form of symmetric matrix of contact probabilities and visualized by structural indicatrices – 2nd order surfaces. A consistent nomenclature of petrographic structures has been proposed. Earlier the method showed itself well in describing the structures of ijolites and urtites of the Khibiny Mountains, as well as amphibolites of the islands of Keretsky Archipelago (the White Sea). Mass application of the method is restrained by the routine procedure of calculating the probabilities of intergranular contacts in petrographic thin sections under a microscope. The problem of modern optical structure analyzers is assignment different sections of the same anisotropic mineral to different minerals, and separation blocks of a mineral individual to different individuals. The paper describes the experience of using the domestic MIU-5M device for scanning petrographic thin sections by the linear method of Rosival. The combination of visual control and minimum automation of the process allows us to achieve convergence of the structural types with results obtained by manual processing of image of petrographic thin section. Additionally, thin sections have been studied, for which the structural types differ with various methods of counting. It has been revealed that the presence of poikilitic ingrowths and features of the mineral composition (the existence of hypergene changes or minerals with similar optical properties) affect the statistics of probabilities. Recommendations are given on the selection of the scanning step depending on the grain size in the studied rock.

(in Russian, стр.7, fig. 4, tables. 0, ref 10, AdobePDF, AdobePDF 0 Kb)