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Geology

Geology
  • Date submitted
    2021-04-15
  • Date accepted
    2022-09-06
  • Date published
    2023-10-27

Gold-rare metal and associated mineralization in the western part of Bolshevik Island, Severnaya Zemlya archipelago

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The presented studies are aimed to determine the formation patterns of the gold-rare metal mineralization within one of the most inaccessible Arctic islands of the Russian Federation, Bolshevik Island of the Severnaya Zemlya archipela-go. The relevance of the work is determined by the high probability of discovering a significant in terms of metal reserves deposit, which is proved by many researchers on the example of known large deposits to be a typical feature of sites with gold-rare metal formation. Obviously, only the possibility of discovering and subsequent development of a deposit of a highly liquid type of mineral, gold, can ensure the profitability of mining production on Severnaya Zemlya. It is established that the main geological, mineralogical, and geochemical features of the gold-rare metal mineralization in the Kropotkinsko-Nikitinskaya metallogenic zone of Bolshevik Island correspond to that of similar ore sites in Russia and the world. The occurrences of other formation types revealed in this metallogenic zone suggest a certain zoning in their distribution: mineralization is located in the apical parts of granitoids and in the nearest halo of hornfelses. At a distance, with an exit from the hornfelsed zone, there are occurrences of a cassiterite-sulphide formation with elevated gold and silver content at the top of the ore column, together with an increased amount of polymetallic ores. Occurrences of gold-quartz and gold-sulphide-quartz formations are localized in fault zones, as a rule, farther from granitoids. The total vertical range of gold mineralization exceeds 300 m. The assignment of all types of mineralization in the Kropotkinsko-Nikitinskaya metallogenic zone of Bolshevik Island to a single hydrothermal process is emphasized by the similar isotope composition of lead galena from heterogeneous occurrences, which determines the age of all mineralization at 200-300 Ma.

How to cite: Evdokimov , A. N., Fokin , V. I., & Shanurenko , N. K. (2023). Gold-rare metal and associated mineralization in the western part of Bolshevik Island, Severnaya Zemlya archipelago. Journal of Mining Institute, 263, 687-697. https://doi.org/10.31897/PMI.2022.94
Geology
  • Date submitted
    2023-04-29
  • Date accepted
    2023-10-11
  • Date published
    2023-10-27

Pink-violet diamonds from the Lomonosov mine: morphology, spectroscopy, nature of colour

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The article presents the results of the first comprehensive study of mineralogical and spectroscopic (IR, PL, EPR) characteristics of diamonds from the Lomonosov mine (Arkhangelskaya pipe) with a unique pink, pink-violet colour. It is shown that all crystals belong to the IaA type, with a total nitrogen content in the range of 500-1500 ppm, with a low degree of aggregation. The colour is heterogeneous, concentrated in narrow twin layers. It is presumably caused by the previously described M 2 centres. The colour shade is affected by the content of P 1 paramagnetic centres ( C -defect). A positive correlation is observed between the colour saturation and the intensity of W 7 paramagnetic centres. A convergent model of the formation of pink diamonds is assumed, according to which the determining factors are the ratio and concentration of structural impurities in the diamond, its thermal history, and conditions of plastic deformation, and not the origin of the diamond and the petrochemical properties of its host rocks.

How to cite: Kriulina , G. Y., Vyatkin , S. V., & Vasilev , E. A. (2023). Pink-violet diamonds from the Lomonosov mine: morphology, spectroscopy, nature of colour. Journal of Mining Institute, 263, 715-723.
Geology
  • Date submitted
    2023-03-30
  • Date accepted
    2023-09-21
  • Date published
    2023-10-27

Mineral composition and thermobarometry of metamorphic rocks of Western Ny Friesland, Svalbard

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The results of the study of mineral composition and microstructure of representative metapelitic and calcic pelitic schist and amphibole-biotite gneiss, occurring in the northern part of the Western Ny Friesland anticlinorium, are reported. Mineral composition was analyzed with a JSM-6510LA scanning electron microscope with a JED-2200 (JEOL) energy dispersive spectrometer. Metamorphic conditions were assessed with various mineral geothermometers (garnet-biotite, Ti-in-biotite, Ti-in-muscovite, Ti-in-amphibole, garnet-amphibole, amphibole-plagioclase, and chlorite) and geothermobarometers (GASP, GBPQ, GRIPS, GBPQ, phengite, etc.). It has been shown that peak temperature and pressure for rocks of the Paleoproterozoic Atomfjella Series forming the western limb of the anticlinorium are consistent with those for the high-pressure part of the upper amphibolite facies (690-720 °С, 9-12 kbar), and the peak temperature and pressure for rocks of the Mossel Series occurring in the eastern limb and rest on the Atomfjella rock sequence, are consistent with the high-pressure part of the lower amphibolite facies (580-600 °С, 9-11 kbar). In addition to the high-temperature parageneses Ms-Bt-Grt-Pl (±Ky, St), Bt-Grt-Pl-Kfs-Cal (±Scp) and Bt-Hbl-Ep-Grt-Pl, the rocks of the both series display the low-temperature assemblage Ms-Chl-Ep-Ab-Prh-Ttn, which was formed upon transition from greenschist to prehnite-pumpellyite facies (260-370 °С).

How to cite: Gulbin , Y. L., Akbarpuran Khaiyati , S. A., & Sirotkin , A. N. (2023). Mineral composition and thermobarometry of metamorphic rocks of Western Ny Friesland, Svalbard. Journal of Mining Institute, 263, 657-673.
Geology
  • Date submitted
    2023-04-23
  • Date accepted
    2023-10-24
  • Date published
    2023-10-27

Mining Museum as a space of science and education in Mining University

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An interdisciplinary investigation is presented focusing on the study of the Mining Museum collections in relation to research, educational and social practices. Natural science and artistic exhibits are considered. The authors made an attempt to determine the significance of the mineralogical collection based on the criteria proposed by I.V.Pekov. For the first time, general statistics on the new minerals in the mineralogical museums of the USSR was collected in 1988; in subsequent years, such information was not published. Collection of the Mining Museum comprises mineral species received after 1988 and having the status of holotypes, neotypes, and cotypes. In anticipation of the 250th anniversary of Saint Petersburg Mining University its special contribution to the progress of science was noted; the merits of scientists were immortalized in the names of minerals stored in the Mining Museum collection. An important role of the Museum in recording and representation of achievements of the Mining University is shown. The authors present the Mining Museum as a special educational space where an objective image of the world is created shaped by the scientific and humanitarian environment. The Museum is regarded as a space for forming the professional identity, important for the successful work of future University graduates. The interior of the Mining Museum designed and created in the 1st half of the XIX century taking into account the ideas about the succession of scientists from different epochs, respect for scientific traditions of antiquity and achievements in the field of studying the world plays a significant role in this process. Images of thinkers of the antiquity in the interiors of the educational and public spaces of the XIX century made it possible to emphasize the importance of cultural correlation with ideas of the Enlightenment. Specific examples from the collection show how the Mining Museum was implementing the scientific and educational goals of the Mining University throughout its history.

How to cite: Dorofeev , D. Y., Borovkova , N. V., & Vasileva М. А. (2023). Mining Museum as a space of science and education in Mining University. Journal of Mining Institute, 263, 674-686.
Geology
  • Date submitted
    2023-08-14
  • Date accepted
    2023-10-25
  • Date published
    2023-10-27

Magmatic system of the Klyuchevskoy volcano according to seismic data and their geomechanical interpretation

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3D analysis of the magma transport and accumulation mechanism in the structure and basement of the Klyuchevskoy volcano preceding 11 eruptions in 2003-2021 has been performed. Using the Frac-Digger method and seismological data from the Kamchatka Branch Federal Research Center United Geophysical Survey Russia Academy of Sciences it has been shown that magma transport from the deep crustal magma chamber (−30 km) is carried out in the vertical fracturing (dykes) mode to the peripheral shallow magma chamber (+1 km). The feeding dykes orientation corresponds to geomechanical conditions of radial or N-NNE extension. This is followed by inclined dykes and sills of various orientations from the peripheral magmatic chamber. Magma accumulation in the peripheral magmatic chamber in the form of sills (in the horizontal fracturing mode at elevations of +0,3 to +2,3 km) contributes to the efficiency of magma degassing and heat exchange with meteoric waters, and to the formation of a high-pressure vapour-gas reservoir with subsequent venting of the volcano channel and its eruption. Three-dimensional analysis of the distribution of flank eruptions of the Klyuchevskoy volcano in 1932-2021 (16 cinder cones) shows their association with two main low-inclined structural surfaces. Changes in the drainage level of the magmatic system are reflected in the volumes and geochemical history of the 1932-2021 flank eruption products.

How to cite: Kiryukhin , A. V., Bergal-Kuvikas , O. V., Lemzikov , M. V., & Zhuravlev , N. B. (2023). Magmatic system of the Klyuchevskoy volcano according to seismic data and their geomechanical interpretation. Journal of Mining Institute, 263, 698-714.
Geology
  • Date submitted
    2023-04-04
  • Date accepted
    2023-06-20
  • Date published
    2023-10-09

Trace elements in the silicate minerals of the Borodino Meteorite (Н5)

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Major (EPMA) and trace (SIMS) element geochemistry in olivine, low-Са pyroxene and mesostasis from porphyritic and barred chondrules, as well as the pyroxene-olivine aggregate and matrix of equilibrated ordinary Borodino chondrite (Н5) is discussed. No differences in major element concentrations in the silicate minerals of the chondrules and matrix of the meteorite were found. The minerals of porphyritic olivine-pyroxene and barred chondrules display elevated trace element concentrations, indicating the rapid cooling of chondrule melt in a nebula, and are consistent with experimental data. The trace element composition of low-Са pyroxene is dependent on the position of a pyroxene grain inside a chondrule (centre, rim, matrix) and the composition of mesostasis is controlled by the type of the object (porphyritic and barred chondrules, pyroxene-olivine aggregate). The depletion in trace elements of low-Са pyroxene from the rims of chondrules in comparison with those from the centre and matrix of the meteorite was revealed. The chondrule rim is affected by interaction with surrounding gas in a nebula, possibly resulting in the exchange of moderately volatile trace elements in low-Са pyroxene and depletion in these elements relative to pyroxene from the centre of the chondrule or matrix of the meteorite. The mesostasis of barred and porphyritic olivine-pyroxene chondrules contains more trace elements than that of porphyritic olivine chondrule and pyroxene-olivine aggregate, suggesting the rapid cooling of these objects or their high liability to thermal metamorphism, which results in the recrystallization of chondrule glass into plagioclase. However, no traces of the elevated effect of thermal metamorphism on the above objects have been revealed. The results obtained indicate no traces of the equilibration of the trace element composition of silicate minerals in equilibrated chondrites.

How to cite: Sukhanova , K. G. (2023). Trace elements in the silicate minerals of the Borodino Meteorite (Н5). Journal of Mining Institute.
Geology
  • Date submitted
    2023-02-07
  • Date accepted
    2023-06-20
  • Date published
    2023-09-06

Origin of carbonate-silicate rocks of the Porya Guba (the Lapland-Kolvitsa Granulite Belt) revealed by stable isotope analysis (δ18O, δ13C)

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Carbonate-silicate rocks of unclear origin have been observed in granulites of the Porya Guba of the Lapland-Kolvitsa Belt within the Fennoscandinavian Shield. The present work aims to reconstruct possible protoliths and conditions of metamorphic transformation of these rocks based on oxygen and carbon isotopic ratios combined with phase equilibria modeling. Isotope analysis and lithochemical reconstructions suggest that carbonate-silicate rocks of the Porya Guba represent metamorphosed sediments (possibly marls) with the isotopic composition corresponding to the Precambrian diagenetically transformed carbonates (δ 18 O ≈ 17.9 ‰, SMOW and δ 13 C ≈ –3.4 ‰, PDB). The chemical composition varies depending on the balance among the carbonate, clay, and clastic components. Significant changes of the isotopic composition during metamorphism are caused by decomposition reactions of primary carbonates (dolomite, siderite, and ankerite) producing CO 2 followed by degassing. These reactions are accompanied by δ 18 O and δ 13 C decrease of calcite in isotopic equilibrium with CO 2 down to 15 ‰ (SMOW) and –6 ‰ (PDB), respectively. The isotopic composition is buffered by local reactions within individual rock varieties, thus excluding any pronounced influence of magmatic and/or metasomatic processes.

How to cite: Krylov , D. P., & Klimova , E. V. (2023). Origin of carbonate-silicate rocks of the Porya Guba (the Lapland-Kolvitsa Granulite Belt) revealed by stable isotope analysis (δ18O, δ13C). Journal of Mining Institute.
Geology
  • Date submitted
    2022-11-29
  • Date accepted
    2023-03-02
  • Date published
    2023-10-27

New data on the composition of growth medium of fibrous diamonds from the placers of the Western Urals

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This article presents the results of studying microinclusions of fluids/melts in diamonds from the placers of the Krasnovishersky District (western slope of the Middle/Northern Urals), which make it possible to establish the evolution of diamond-forming media in the subcontinental lithospheric mantle of the eastern margin of the East European craton. Impurity composition of the studied crystals reveals three different types of diamonds, the formation of which was associated with separated metasomatic events. Microinclusions in B-type diamonds containing A and B nitrogen defects reflect an older metasomatic stage characterized by the leading role of silicic and low-Mg carbonatitic fluids/melts. The second stage is associated with the growth of A-type diamonds containing nitrogen exclusively in the form of A-centers. At this stage, the formation of diamonds was related with low-Mg carbonatitic media, more enriched in MgO, CaO, CO 2 , and Na 2 O compared to B-type diamonds. The third stage probably preceded the eruption of the transporting mantle melt and led to the formation of C-type diamond containing A and C nitrogen defect centers and microinclusions of silicic to low-Mg carbonatitic composition. The recorded trend in the evolution of diamond-forming fluids/melts is directed towards more carbonatitic compositions. Fluids/melts are probably sourced from eclogitic and pyroxenitic mantle substrates.

How to cite: Gubanov , N. V., Zedgenizov , D. A., Vasilev , E. A., & Naumov , V. A. (2023). New data on the composition of growth medium of fibrous diamonds from the placers of the Western Urals. Journal of Mining Institute, 263, 645-656.
Geology
  • Date submitted
    2022-04-13
  • Date accepted
    2023-02-15
  • Date published
    2023-08-28

The impact of secondary mineral formation on Na-K-geothermometer readings: a case study for the Valley of Geysers hydrothermal system (Kronotsky State Nature Biosphere Reserve, Kamchatka)

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The temperature in the Valley of Geysers (Kamchatka) geothermal reservoir calculated using the feldspar Na-K-geothermometer has been steadily increasing over the past 10 years on average from 165 to 235 °C, which is close to the temperature values of a hydrothermal explosion of the steam and water mixture. For the analysis of chemical geothermometers, TOUGHREACT-simulation was used, with the help of which the previously known Na-K feldspar geothermometer was reproduced on a single-element model and new formulas were obtained for three Na-K geothermometers: zeolite, smectite, and based on volcanic glass. Data of chemical analysis for the period 1968-2018, in which the chloride ion is considered as an inert tracer of geofiltration processes, indicates that after 2007 a significant inflow of infiltration water (its mass fraction is estimated from 5 to 15 %) into the Geyser reservoir. It is assumed that the Na-K increased values of the feldspar geothermometer are not the result of the temperature increase in the Geyser reservoir, but the effect of smectite water dilution.

How to cite: Sergeeva , A. V., Kiryukhin , A. V., Usacheva , O. O., Rychkova , T. V., Kartasheva , E. V., Nazarova , M. A., & Kuzmina , A. A. (2023). The impact of secondary mineral formation on Na-K-geothermometer readings: a case study for the Valley of Geysers hydrothermal system (Kronotsky State Nature Biosphere Reserve, Kamchatka). Journal of Mining Institute, 262, 526-540.
Geology
  • Date submitted
    2022-12-03
  • Date accepted
    2023-02-03
  • Date published
    2023-08-28

Garnetites from Marun-Keu eclogite complex (Polar Urals): geochemistry and the problem of genesis

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A comprehensive mineralogical and geochemical characterization (XRF, ICP-MS, SEM-EDS, SIMS methods) of garnetites and their protoliths from the Marun-Keu complex (Polar Urals), one of the key objects in understanding the evolution of the Uralian Orogen, is presented. Garnetites and their protoliths from the Marun-Keu complex, Polar Urals, a key locality for understanding the evolution of the Uralian Orogen, are described mineralogically and geochemically using XRF, ICP-MS, SEM-EDS and SIMS methods. Ultramafic (in most cases) and mafic rocks are understood as protoliths for garnetites. A general trend for garnetites is an increase in total REE concentration relative to that of their protoliths. All the analyzed garnetites display a considerable decrease in Cr, Ni and Co. V concentration in the garnetites is also lower than that of the protoliths, though not so markedly. Garnets from garnetites evolving after peridotites generally exhibit elevated (relative to garnets from garnetites evolving after mafic rocks, such as porphyrites) Prp and lowered Alm content, which seems to be due to high Mg concentration in the protolith. In garnetites after peridotites a garnet exhibiting an uncommon non-differentiated REE spectrum with a considerable positive Eu-anomaly was found, which could be due to the inheritance of a REE spectrum by garnet from a precursor mineral, in this case plagioclase. Slyudyanaya Gorka garnetites were probably formed from mafic and ultramafic rocks in oceanic crust, which migrated to higher levels of the section under the influence of the crustal fluid flowing along fracturing zones.

How to cite: Salimgaraeva , L. I., & Berezin , A. V. (2023). Garnetites from Marun-Keu eclogite complex (Polar Urals): geochemistry and the problem of genesis. Journal of Mining Institute, 262, 509-525.
Geology
  • Date submitted
    2022-09-26
  • Date accepted
    2023-03-23
  • Date published
    2023-06-23

A new diamond find and primary diamond potential of the Chetlas uplift (Middle Timan)

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In the previously poorly studied southeastern part of the Chetlas uplift in the Middle Timan, a new occurrence of diamond satellite minerals and a diamond grain were found in the modern channel sediments of the Uvuy River basin. In order to assess the prospects of the area under consideration for identification of diamondiferous objects of practical interest, a characteristic of chromium-bearing pyropes and chromospinelides as the main kimberlite of diamond satellite minerals are given and the diamond grain itself is described. The material for the research was 16 schlich samples, each with a volume of 8 to 15 l. The minerals were studied using optical and scanning electron microscopy, Raman spectroscopy, laser luminescence and X-ray diffraction (Debye – Sherrer method). It is shown that among the pyropes, most of which correspond in composition to minerals of the lherzolite paragenesis, there are varieties belonging to the dunite-harzburgite paragenesis, including those belonging to diamond phase stability regions. Among the studied chromospinelides, chrompicotites and aluminochromites similar in composition to those found in rocks such as lherzolites and harzburgites, as well as in kimberlites, were identified. A diamond grain found in one of the samples has the form of a flattened intergrowth with distinct octahedron faces, complicated by co-growth surfaces with other mineral grains that have not been preserved to date. The discovery of the diamond and the established signs the formation of aureoles of the diamond satellites minerals in the channel sediments of the studied area open up the prospects for discovering their primary sources here.

How to cite: Pystin , A. M., Glukhov , Y. V., & Bushenev , A. A. (2023). A new diamond find and primary diamond potential of the Chetlas uplift (Middle Timan). Journal of Mining Institute.
Geology
  • Date submitted
    2022-12-01
  • Date accepted
    2023-01-19
  • Date published
    2023-05-18

Inclusions of diamond crystals in the tourmaline of the schorl-uvite series: problems of genesis

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The mineralogical and geochemical features of diamond-bearing tourmaline crystals (schorl-uvite series) from garnet-clinopyroxene rocks of the Kumdy-Kol deposit (Northern Kazakhstan) have been studied in detail. The formation of the main rock-forming minerals (garnet + K-bearing clinopyroxene) occurred in the diamond stability field at 4-6 GPa and 950-1000 °C. Crystallization of K-bearing clinopyroxene at these parameters is possible in the presence of an ultra-potassic fluid or melt formed because of crustal material melting in subduction zones. Tourmaline crystals (up to 1 cm) containing diamond inclusions perform veins crosscutting high-pressure associations. The composition of individual zones varies from schorl to uvite within both a single grain and the sample as a whole. The potassium content in this tourmaline does not exceed 0.1 wt.% K 2 O, and the isotopic composition of boron δ 11 B varies from –10 to –15.5 ‰, which significantly differs from the previously established isotopic composition of boron in maruyamaite crystals (δ 11 B 7.7 ‰ in the core and –1.2 ‰ in the rim) of the same deposit. Analysis of the obtained data on δ 11 B in the tourmalines from the diamond-grade metamorphic rocks within the Kumdy-Kol deposit suggests the existence of two boron sources that resulted in crystallization of K-bearing tourmaline crystals (maruyamaite-dravite series) and potassium-free tourmalines of the schorl-uvite series.

How to cite: Korsakov , A. V., Mikhailenko , D. S., Zhang , L., & Xu , Y.-G. (2023). Inclusions of diamond crystals in the tourmaline of the schorl-uvite series: problems of genesis. Journal of Mining Institute.
Geology
  • Date submitted
    2022-08-22
  • Date accepted
    2023-02-02
  • Date published
    2023-08-28

Wodginite as an indicator mineral of tantalum-bearing pegmatites and granites

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In the composition of tantalum-niobates, the tin-bearing wodginite group minerals (WGM) were found: wod-ginite, titanowodginite, ferrowodginite, ferrotitanowodginite, lithiowodginite, tantalowodginite, “wolframowodginite”. We reviewed the worldwide research on WGM and created a database of 698 analyses from 55 sources including the author's data. WGM are associated with Li-F pegmatites and Li-F granites. Wodginite is the most prevalent mineral, occurring in 86.6 % of pegmatites and 78.3 % of granites. The occurrence of WGM in granites and pegmatites differs. For instance, titanowodginite and “wolframowodginite” occur three times more frequently in granites than in pegmatites, whereas lithiowodginite and tantalowodginite do not appear in granites at all. The difference between WGM in granites and pegmatites is in finer grain size, higher content of Sn, Nb, Ti, W, and Sc; lower content of Fe 3+ , Ta, Zr, Hf; higher ratio of Mn/(Mn + Fe); and lower ratio of Zr/Hf. The evolutionary series of WGM in pegmatites are as follows: ferrowodginite → ferrotitanowodginite → titanowodginite → “wolframowodginite” → wodginite → tantalowodginite; in granites: ferrowodginite → ferrotitanowodginite → “wolframowodginite” → wodginite → titanowodginite. WGM can serve as indicators of tantalum-bearing pegmatites and granites. In Russia the promising sources of tantalum are deposits of the Far Eastern belt of Li-F granites containing wodginite.

How to cite: Alekseev , V. I. (2023). Wodginite as an indicator mineral of tantalum-bearing pegmatites and granites. Journal of Mining Institute, 262, 495-508. https://doi.org/10.31897/PMI.2023.19
Geology
  • Date submitted
    2021-12-21
  • Date accepted
    2022-06-20
  • Date published
    2022-11-10

Scientific justification of the perforation methods for Famennian deposits in the southeast of the Perm Region based on geomechanical modelling

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The article presents the results of analysing geological structure of the Famennian deposits (Devonian) in the Perm Region. Numerical modelling of the distribution of inhomogeneous stress field near the well was performed for the two considered types of perforation. With regard for the geometry of the forming perforation channels, numerical finite element models of near-wellbore zones were created considering slotted and cumulative perforation. It is ascertained that in the course of slotted perforation, conditions are created for a significant restoration of effective stresses and, as a result, restoration of reservoir rock permeability. Stress recovery area lies near the well within a radius equal to the length of the slots, and depends on the drawdown, with its increase, the area decreases. From the assessment of failure areas, it was found that in case of slotted perforation, the reservoir in near-wellbore zone remains stable, and failure zones can appear only at drawdowns of 10 MPa and more. The opposite situation was recorded for cumulative perforation; failure zones near the holes appear even at a drawdown of 2 MPa. In general, the analysis of results of numerical simulation of the stress state for two simulated types of perforation suggests that slotted perforation is more efficient than cumulative perforation. At the same time, the final conclusion could be drawn after determining the patterns of changes in permeability of the considered rocks under the influence of changing effective stresses and performing calculations of well flow rates after making the considered types of perforation channels.

How to cite: Chernyshov , S. E., Popov , S. N., Varushkin , S. V., Melekhin , A. A., Krivoshchekov , S. N., & Ren , S. (2022). Scientific justification of the perforation methods for Famennian deposits in the southeast of the Perm Region based on geomechanical modelling. Journal of Mining Institute, 257, 732-743. https://doi.org/10.31897/PMI.2022.51
Geology
  • Date submitted
    2022-02-22
  • Date accepted
    2022-09-15
  • Date published
    2022-11-10

The problem of the genesis of the Mesoarchean aluminosilicate rocks from the Karelian craton and their possible use as a quartz-feldspar raw material

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The article presents original data obtained in the study of the chemical and mineral compositions of the Late Archean aluminosilicate rocks (formerly called silicites) from the Koikari and Elmus structures of the Vedlozero-Segozero greenstone belt of the Karelian craton (Central Karelia). A comprehensive study of these formations revealed their complex genesis as a result of the late imposition of hydrothermal and metamorphic alteration on sedimentary and volcanic-sedimentary rocks of feldspar-quartz composition. Due to the superimposed metasomatic (temperature?) impact on feldspar-quartz siltstones, Fe was removed from microinclusions in quartz and feldspar and its oxides were concentrated along the grain boundaries. Minerals such as monazite, parisite, allanite are also located either along the grain boundaries of quartz and feldspars, or together with calcite they fill microfractures, which makes it possible to get rid of them when preparing quartz-feldspar concentrates using various beneficiation technologies. According to most indicators limited by GOSTs, individual samples in their natural form meet the requirements for quartz-feldspar raw materials for use as part of batch in the production of diverse types of glass. Additional beneficiation of the feedstock (grinding, screening into narrow classes and further magnetic separation) leads to a decrease in Fe 2 O 3 content to normalized values. The resulting quartz-feldspar concentrates with various particle sizes can be used in the production of building material and fine ceramics (sanitary and ceramic products, facing and finishing tiles, artistic, household porcelain and faience). The homogeneity of the mineral and chemical composition, the possibility of compact extraction and beneficiation (including in mobile small-sized installations) increase the prospects and competitiveness of this non-traditional feldspar raw material from Central Karelia.

How to cite: Kondrashova , N. I., Bubnova , T. P., & Medvedev , P. V. (2022). The problem of the genesis of the Mesoarchean aluminosilicate rocks from the Karelian craton and their possible use as a quartz-feldspar raw material. Journal of Mining Institute, 257, 720-731. https://doi.org/10.31897/PMI.2022.65
Geology
  • Date submitted
    2022-04-29
  • Date accepted
    2022-07-21
  • Date published
    2022-11-10

Deep structure, tectonics and geodynamics of the Sea of Okhotsk region and structures of its folded frame

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The use of the zonal-block model of the earth's crust for the construction of regional tectonic schemes and sections of the earth's crust based on a complex of geological and geophysical data makes it possible to consider the resulting maps and sections as tectonic models. The main elements of such models are blocks with an ancient continental base and interblock zones formed by complexes of island arcs, an accretionary prism, or oceanic crust. The developed geotectonic model of the Sea of Okhotsk region reflects the features of the deep structure, tectonics, and geodynamics. The Cimmerian Novosibirsk-Chukotka, Verkhoyansk-Kolyma, Kolyma-Omolon, and Amur folded regions and the Alpides of the Koryak-Kamchatka and Sakhalin-Sikhote-Alin folded regions are developed along the northern, western, and southern boundaries of the Sea of Okhotsk megablock with a continental crust type. From the east, the megablock is limited by oceanic basins and island arcs.

How to cite: Egorov , A. S., Bolshakova , N. V., Kalinin , D. F., & Ageev , A. S. (2022). Deep structure, tectonics and geodynamics of the Sea of Okhotsk region and structures of its folded frame. Journal of Mining Institute, 257, 703-719. https://doi.org/10.31897/PMI.2022.63
Geology
  • Date submitted
    2021-04-04
  • Date accepted
    2022-04-26
  • Date published
    2022-07-26

Vendian age of igneous rocks of the Chamberlain valley area (Northern part of the Wedel Jarlsberg Land, Svalbard Archipelago)

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The geological structure, structural relations with the underlying complexes, mineral composition, age and origin of sedimentary-volcanogenic and intrusive formations of the Chamberlain valley area (northern part of the Wedel Jarlsberg Land, Svalbard Archipelago) are considered. As a result of the studies, two stages of the Late Precambrian endogenous activity in this area have been identified. For the first time the Vendian ages (593-559 Ma) of intrusive (dolerites) and effusive (basalts, andesites, tuffs) rocks were determined by U-Pb-method (SHRIMP-II) for Svalbard Archipelago. At the same time, the Grenville ages for large bodies of gabbro-diorites, metadolerites bodies (1152-967 Ma), and metagranites (936 Ma) were determined for the first time for this area, which correlates well with the ages of magmatic formations obtained earlier in the southern part of Wedel Jarlsberg Land. A detailed petrographic and petrochemical characterization of all the described objects were compiled and the paleotectonic conditions of their formation were reconstructed. Based on these data, the Chemberlendalen series, which is dated to the Late Vendian, and the Rechurchbreen series, which the authors attribute to the Middle Riphean and correlate with the lower part of the Nordbucht series are distinguished. The data obtained indicate a two-stage Precambrian magmatism in this area of the Svalbard archipelago and, most importantly, provide evidence for the first time ever of endogenous activity on Svalbard in the Vendian time. This fact makes it possible to reconsider in the future the history of the formation of folded basement of the Svalbard archipelago and the nature of the geodynamic conditions in which it was formed.

How to cite: Sirotkin , A. N., & Evdokimov , A. N. (2022). Vendian age of igneous rocks of the Chamberlain valley area (Northern part of the Wedel Jarlsberg Land, Svalbard Archipelago). Journal of Mining Institute, 255, 419-434. https://doi.org/10.31897/PMI.2022.20
Geology
  • Date submitted
    2022-01-28
  • Date accepted
    2022-04-26
  • Date published
    2022-07-26

On the presence of the postmagmatic stage of diamond formation in kimberlites

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On nowadays multiphase and the facies heterogeneity of the formations are distinguished at the study of kimberlite pipes. Most researchers associate the formation of diamonds only with the mantle source. To date, satellite minerals with specific compositions associated with kimberlite diamonds have been identified as deep mantle diamond association. They are extracted from the concentrate of the kimberlites heavy fraction and may reflect the diamond grade of the pipe. For some minerals in the diamond association, however, they can not be reliable. Some researchers also revealed shallow diamond associations, related to the formation of serpentine, calcite, apatite, and phlogopite. There is recent data on the formation of diamonds in rocks of the oceanic crust. In the last years microdiamonds were identified in chromites of the oceanic crust in association with antigorite formed at 350-650 °C and 0.1-1.6 GPa. As a result, the authors established a postmagmatic kimberlitic stage of diamond formation associated with secondary mineral associations based on the experimental and mineralogical data for the conditions of the shallow upper mantle and crust. Mineralogical and petrographic studies of Angolan kimberlite pipe show that antigorite is the indicator mineral of this stage.

How to cite: Simakov , S. K., & Stegnitskiy , Y. B. (2022). On the presence of the postmagmatic stage of diamond formation in kimberlites. Journal of Mining Institute, 255, 319-326. https://doi.org/10.31897/PMI.2022.22
Geology
  • Date submitted
    2022-02-24
  • Date accepted
    2022-05-25
  • Date published
    2022-07-26

Litsa uranium ore occurrence (Arctic zone of the Fennoscandian Shield): new results of petrophysical and geochemical studies

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Mineralogical, petrophysical and geochemical studies have been carried out to determine the sequence and formation conditions of uranium mineralization within the Litsa ore occurrence (Kola Region). Mineralogical studies show the following formation sequence of ore minerals: uraninite – sulfides – uranophane, coffinite, pitchblende. Two stages of uranium mineralization are distinguished: Th-U (1.85-1.75 Ga) and U (400-300 Ma). The distribution of physical properties of rocks in the area is consistent with the presence of two temporal stages in the formation of mineralization with different distribution and form of uranium occurrence in rocks. The factors that reduce rock anisotropy are the processes of migmatization and hydrothermal ore mineralization, which heal pores and cracks. Fluid inclusions in quartz studied by microthermometry and Raman spectroscopy contain gas, gas-liquid and aqueous inclusions of different salinity (1.7-18.4 wt.% NaCl-eq.). According to homogenization temperatures of inclusions in liquid phase, the temperature of the Paleoproterozoic and Paleozoic stages of uranium mineralization at the Litsa ore occurrence is ~ 300 and 200 °С, respectively. Correlations of the spatial distribution of elastic anisotropy index with an elevated radioactive background allow using this petrophysical feature as one of the prognostic criteria for uranium and complex uranium mineralization when carrying out uranium predictive work.

How to cite: Il’chenko , V. L., Afanasieva , E. N., Kaulina , T. V., Lyalina , L. M., Nitkina , E. A., & Mokrushina , O. D. (2022). Litsa uranium ore occurrence (Arctic zone of the Fennoscandian Shield): new results of petrophysical and geochemical studies. Journal of Mining Institute, 255, 393-404. https://doi.org/10.31897/PMI.2022.44
Geology
  • Date submitted
    2022-02-26
  • Date accepted
    2022-04-27
  • Date published
    2022-07-26

Type intrusive series of the Far East belt of lithium-fluoric granites and its ore content

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The evolution and ore content of granitoid magmatism in the Far East belt of lithium-fluoric granites lying in the Russian sector of the Pacific ore belt have been studied. Correlation of intrusive series in the Novosibirsk-Chukotka, Yana-Kolyma and Sikhote-Alin granitoid provinces of the studied region allowed to establish the unity of composition, evolution, and ore content of the Late Mesozoic granitoid magmatism. On this basis, a model of the type potentially ore-bearing intrusive series of the Far East belt of lithium-fluoric granites has been developed: complexes of diorite-granodiorite and granite formations → complexes of monzonite-syenite and granite-granosyenite formations → complexes of leucogranite and alaskite formations → complexes of rare-metal lithium-fluoric granite formation. The main petrological trend in granitoid evolution is increasing silicic acidity, alkalinity, and rare-metal-tin specialization along with decreasing size and number of intrusions. At the end of the intrusive series, small complexes of rare-metal lithium-fluoric granites form. The main metallogenic trend in granitoid evolution is an increasing ore-generating potential of intrusive complexes with their growing differentiation. Ore-bearing rare-metal-granite magmatism of the Russian Far East developed in the Late Cretaceous and determined the formation of large tungsten-tin deposits with associated rare metals: Ta, Nb, Li, Cs, Rb, In in areas with completed intrusive series. Incompleteness of granitoid series of the Pacific ore belt should be considered as a potential sign of blind rare-metal-tin mineralization. The Far East belt of lithium-fluoric granites extends to the Chinese and Alaskan sectors of the Pacific belt, which allows the model of the type ore-bearing intrusive series to be used in the territories adjacent to Russia.

How to cite: Alekseev , V. I. (2022). Type intrusive series of the Far East belt of lithium-fluoric granites and its ore content. Journal of Mining Institute, 255, 377-392. https://doi.org/10.31897/PMI.2022.21
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