Vulkanologiâ i sejsmologiâ
ISSN (PRINT): 0203-0306
Media registration certificate: No. 0110147 dated 02/05/1993
Founder: Institute of Volcanology and Seismology, Far Eastern Branch of the Russian Academy of Sciences (Petropavlovsk-Kamchatsky), Russian Academy of Sciences (Moscow)
Editor-in-Chief: Sobisevich Alexey Leonidovich Doctor of Physical and Mathematical Sciences, Corresponding Member of the Russian Academy of Sciences
Number of issues per year: 6
Indexation: RISC, List of Higher Attestation Commissions, RSCI Core, white list (2nd level)
Journal of Volcanology and Seismology is an international peer-reviewed journal that publishes theoretical and experimental studies, communications, and reports on volcanic, seismic, geodynamic, and magmatic processes occurring in the areas of island arcs and other active regions of the Earth. In particular, the journal looks at present-day land and submarine volcanic activity; Neogene–Quaternary volcanism; mechanisms of plutonic activity; the geochemistry of volcanic and postvolcanic processes; geothermal systems in volcanic regions; and seismological monitoring. In addition, the journal surveys earthquakes, volcanic eruptions, and techniques for predicting them. The journal welcomes manuscripts from all countries.
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Vol 17, No 5 (2023)
Articles
Properties of Magmatism, Hydrothermal-Metasomatic and Filtration-Transport Processes in Uranium-Bearing Volcanogenic Structures
Abstract
Creation of a refined conceptual model for the formation of volcanogenic uranium deposits includes researches of the nature of magmatic, hydrothermal-metasomatic and filtration-transport processes, as well as physico-chemical conditions for the transfer and deposition of uranium. We considered these issues using the examples of the Streltsovskaya caldera and the ore field of the same name in Eastern Transbaikalia, the Xiangshan volcanic structure in South China, and the McDermitt caldera in the western United States (Oregon and Nevada states). According to the IAEA classification [Geological Classification …, 2018], these ore fields and deposits belong to the volcanogenic (volcanic-related) type. In the Streltsovsky and Xiangshan ore fields, a combination of volcanogenic in the cover and granitic (granite-related) in the basement types of deposits is observed. The main part of uranium industrial deposits of volcanic type in these regions was formed during the Mesozoic and Cenozoic epochs (although more ancient, Paleozoic, objects are known in the world). Despite different time intervals of the ore-bearing volcanogenic structures formation, many features of magmatic, hydrothermal, and filtration-transport processes in them are very similar. It is assumed that these features are due to the general influence of intraplate tectonic regimes or the evolution of the outer parts of the ocean-continent zones where magmatic activity produced volcanism of the bimodal series in the predominant sequence mafic ‒ felsic volcanics ‒ mafic, and the migration of uranium-transporting fluids was set by the joint action of seismogeodynamic and thermoconvective processes.
3-25
Geological Structure Features and Rocks Composition of Kronotsky Volcano, the Largest Stratovolcano in the Frontal Zone of the Eastern Volcanic Belt of Kamchatka
Abstract
Based on the results of 2020‒2022 field works, this paper presents a characterization of the geological structure and whole rock composition of Kronotsky volcano, one of the poorly studied eruptive centers of the Eastern Volcanic Belt (EVB) of Kamchatka. The volume of the volcanic edifice is estimated at 350 km3, that significantly exceeds the volumes of other stratovolcanoes of the frontal zone of EVB. Rocks of a volcano are presented by low-K, high-Fe tholeiitic basalts and basaltic andesites (SiO2 = 47.04–53.15 wt %; K2O = = 0.24‒0.65 wt %; FeO*/MgO = 1.2‒2.89). The basalts show extremely low contents of silica, potassium, titanium, and phosphorus in comparison with rocks of other frontal volcanoes of Kamchatka. The revealed petrochemical features were used to clarify the belonging of the objects located at the junction of Kronotsky and Krasheninnikov volcanic edifices. The obtained data will serve as the background for further petrological and geochemical studies of the volcano, and also may be used for reconstruction the sequence of volcanic events in this area, including clarification of the history of Kronotsky Lake formation.
26-45
Tephra from the Island Intra-Plate-Oceanic Volcano Cumbre-Vyaha (Eruption 2021)
Abstract
Comprehensive mineralogical and geochemical studies of a representative sample of tephra from the Cumbre-Vyaha volcano (2020–2021 eruption), which has a gravel-psammitic granulometric composition and is characterized by an anomalously high degree of particle vesicularity, have been carried out. In terms of bulk chemical composition, this tephra corresponds to the transition from alkaline picrobasalts to alkaline basalts, differing fundamentally from the tephra ashes of marginal continental volcanoes. The studied tephra contains 45 trace elements with a total content of up to 2333 ppm, which exceeds that in the tephra of island-arc volcanoes. According to the ratio of geochemical criteria, tephra from Cumbre-Vyaha correspond to the average values for within-plate volcanoes in the oceans. The geochemical feature of the studied tephra is a strong enrichment in lanthanides, noble and platinoid metals. H2, CO, CO2, H2O, CH4, C2H4, C2H6, C3H6, C3H8 were found in the composition of the lithogenic gas phase separated by heating from the studied tephra. The proportions between inorganic components in the gas phase generally correspond to the boundary region between crustal and mantle-crustal derivatives, but a relatively low water content is found. Olivine of composition Fo73–84, essentially diopside clinopyroxene, andesine-bytovnite plagioclases, chrome spinels, phase-homogeneous solid solutions of ilmenite in magnetite, phases of Ni-Cu-bearing native iron, quartz, and sodium hydroxyl chlorides were identified and studied in microlites. In addition, dispersed carbon matter with carbon isotopic composition δ13СPDB = –30…–24‰ was found in the Cumbre-Vyaha tephra, which corresponds to the carbon isotope composition in abiogenic carbonaceous substances of volcanic origin. The totality of the results of mineralogical and geochemical studies characterizes the Cumbre-Vyaha volcano as a typical representative of within-plate oceanic plume volcanoes.
46-62
Conditions of Formation of Epithermal Mineralization of the Kyplatap Volcanic Field (Central Chukotka)
Abstract
The article considers the geochemical features and conditions of the formation of substantially silver mineralization of the Kyplatap volcanic field (KVF), of the Chaunsky zone, of the Central Chukchi Sector, of the Okhotsk-Chukchi volcanic belt (OChVB). New data on the composition, distribution and grade of trace elements, including REE in ores, are presented. The noticeable enrichment REE of the studied samples, the predominance of light lanthanides over heavy ones, very low Eu/Sm ratios (\( \ll {\kern 1pt} 1\)), weakly inclined near–chondrite spectra with obvious Eu minima are typical for the epithermal ore-forming system of the KVF. The Ce/Ce* vary from slightly negative to moderately positive values (from 0.81 to 1.38), and the Eu/Eu* vary from 0.28 to 0.7. This combination of Ce/Ce* and Eu/Eu* indicates the oxidative conditions prevailing during ore formation. The results of thermo- and cryometric studies of fluid inclusions in quartz allowed us to establish that the ore-forming fluid contained Na, Mg and K chlorides, epithermal mineralization was deposited by homogeneous hydrothermal fluids with salt concentrations (0.3–6.2 wt. %-eq. NaCl), fluid density – 0.60–0.87 g/cm3, at temperatures from 203 to 343°C, water vapor pressure varied from 40 to 140 bar. The obtained geochemical and thermometric data confirm the assumption put forward earlier – that the studied mineralization of KVF belongs to the intermediate sulfidation epithermal class. These data point to andesite magmas and meteoric waters as the most likely sources of fluids. The information in the article is of practical importance for regional predictive metallogenic constructions, prospecting and evaluation of epithermal Au–Ag deposits.
63-73
Model of the Seismic Rupture Surface of the Chignik Earthquake (Alaska, USA) 07.29.2021 Based on SAR Interferometry and GNSS Data
Abstract
The paper presents a new rupture model for the Mw = 8.2 “Chignik” earthquake, which occurred off the coast of the Alaska Peninsula on 29.07.2021. The model is based on the Earth’s surface displacement fields obtained by InSAR (Interferometric synthetic aperture radar) method using images of the ESA Sentinel-1 satellites from 17.07 to 10.08.2021 and data on horizontal displacements at nearest permanent GPS sites from 18.07 to 08.08.2021. Obtained displacement fields include both coseismic and part of postseismic displacements. When constructing a model of the seismic rupture surface, we used F. Pollitz’s solution of the problem of the displacement fields at the surface of a spherical radially stratified planet caused by displacements on a rectangular discontinuity located inside it. For the regularization of the inverse problem, we added the condition that the direction of slip on each element of the fault plane is close to the rake angle, determined from seismological data. In the constructed model, the seismic rupture area was approximated by a single plane with a length of 225 km along the strike, 126 km along the dip, divided into 48 identical rectangles. According to the constructed model, the type of displacements is almost pure thrust, and displacements, in general, occurred throughout all the source area. The maximum displacement was 5.7 m, with an average displacement over the entire plane of 2.2 m, which is close to the USGS and GCMT estimates derived from seismological data.
74-83
Fundamentals of the Phenomenological Theory of Earthquakes
Abstract
Phenomenology is a unity of principles and methods for investigating the essence of phenomena. This article is a brief review of a series of works carried out by the authors over the past ten years. The general thrust of the works is that phenomenological ideas of physics are used to analyze earthquakes. A perfect model of phenomenological theory is thermodynamics. Maxwell’s electrodynamics is also a perfect example of phenomenological theory. Earthquake phenomenology is still far from reaching that level. In the system of rational knowledge of geodynamics, we have so far reached the status of a preliminary view of the subject, methods, and tasks of the future phenomenological theory of earthquakes. Nevertheless, already at this stage it is clearly visible the perspective of the proposed approach to the construction of the theory. The article shows by concrete examples that it is useful to use phenomenological representations of general physics when searching for the bases of the theory and when processing and analyzing specific manifestations of seismicity.
84-94