Based on the analysis of the tectonophysical characteristics of the actual seismofocal zone (SFZ) in the lithosphere of the Kuril-Kamchatka region and adjacent Oceanic areas, we estimated the boundary conditions necessary for constructing the quantitative models of heat and mass transfer dynamics in compacted heterophase media under active volcanoes located over the mantle and crustal magmatic sources of the ocean–continent transition regions of the northwestern sector of the Pacific Ocean.The methodology of obtaining the information used for developing of the mathematical models of magmatogenic processes includes: 1) the study of individual porphyry deposits associated with active fluid volcanogenic systems; 2) the study of morphological structures using cosmic satellite images (Sharapov et al., 1980); 3) the study of mantle and crust xenoliths of volcanics (Kutyev, Sharapov, 1979; Sharapov et al., 2009, 2017, 2020); 4) parametric tectono-physical analysis of the modern SFZ of the studied region (Sharapov et al., 1984, 1992); 5) experimental modeling of the processes of deformation Earth's crust and lithospheric mantle rocks of modern SFZ (Sharapov et al., 1984, 1992); 6) construction of mathematical models of the petrogenesis under volcanoes (Sharapov et al., 2007, 2020)According to data on the structure of the Earth's crust under the Avacha volcano; (Koulakov et al., 2014), permeable zones are linear fractures 2-4 km wide, which are conductors of melts and magmatogenic fluids coming from magmatic systems (Koloskov et al., 2014).An analysis of the time characteristics of formation porphyric deposits in the active margins of the Pacific Ocean (Sharapov et al., 2013) showed that more than 70% of the described deposits are formed during the evolution of fluid mantle-crustal ore-magmatic systems. This study analyzes the data on the structure of the modern SFZ of Kamchatka and the Kuril Island arc, used in constructing a model of heat and mass transfer under volcanoes.Based on the analysis of the tectonophysical characteristics of the actual seismofocal zone (SFZ) in the lithosphere of the Kuril-Kamchatka region and adjacent Oceanic areas, we estimated the boundary conditions necessary for constructing the quantitative models of heat and mass transfer dynamics in compacted heterophase media under active volcanoes located over the mantle and crustal magmatic sources of the ocean–continent transition regions of the northwestern sector of the Pacific Ocean.TAn analysis of the time characteristics of formation porphyric deposits in the active margins of the Pacific Ocean (Sharapov et al., 2013) showed that more than 70% of the described deposits are formed during the evolution of fluid mantle-crustal ore-magmatic systems. This study analyzes the data on the structure of the modern SFZ of Kamchatka and the Kuril Island arc, used in constructing a model of heat and mass transfer under volcanoes.RNF grant 24-27-004

This study focuses on the ability of spinel crystals in ultramafic xenoliths, like zircon, to store the primary composition and structure when exposed to magma fluid flows or the thermal heating of ultramafic fragments in magma flows during volcanic eruptions. Mantle ultramafic rock xenoliths from explosives of the Avacha Volcano in Kamchatka have different facies of their metasomatic changes above the magma chamber. An alternative hypothesis of their source is from fragments of layered mafic intrusions containing spinels, which store initial petrogenetic records of the original magma melt. Experiments were conducted to prove this idea using a Budker Institute of Nuclear Physics (INP SB RAS) unit. Large scales of change in the composition and structure of spinel crystals were caused by the hot fluids from melted xenolith sites.

The paper presents a non-isothermal model of hydrodynamic heating of lithospheric rocks above magma chambers in application to the seismic focal zone of the Kamchatka region and associated volcanic arcs. The effect of convective heating of mantle and crustal rocks on dynamics of metasomatic changes and convective melting was studied. In the existing models of ore-forming systems, fluid mass transfer is determined mainly by the retrograde boiling of magmas in meso-abyssal intrusive chambers. Analysis of the manifestations of deposits of the porphyry formation of the Pacific Ocean active margins shows the decisive participation in their formation of mantle-crust ore-igneous systems. The model of convective heat-mass transfer in fluid mantle-crust systems coupled with magma chambers is designed with the consideration of effects of interphase interaction in rocks of permeable zones above igneous fluid sources. Numerical simulation of the dynamics of fluid systems under the volcanoes of the frontal zone of Kamchatka shows altered ultramafic rocks in metasomatic zoning and the presence of facial changes in the mineral composition of wehrlitized rocks. In the mantle wedge of the northwestern margin of the Pacific Ocean, over which epicontinental volcanic arcs developed in the post-Miocene stage, there is possible combination of the products of different-time and different-level igneous systems in the same permeable "earth's crust-lithospheric mantle" transition zones. Assuming that the "cratonization" of volcanic sections of the continental Earth's crust follows the "metasomatic granitization" pattern, the initial element of which is the wehrlitization of mantle wedge ultramafic rocks, the processes of metasomatic fertilization of mantle wedge rocks were investigated using a flow-through multiple-reservoir reactor. In the seismically active regions of the Pacific transition lithosphere, specific conditions for heating of areas of increased permeability above mantle fluid sources should be recorded. Metasomatic columns in such fluid systems can describe the formation of at least three levels of convective melting of metasomatized mantle wedge substrates, as well as the formation of a region of high-temperature fluid change of mafic intrusion rocks in the Earth's crust. The work was financially supported by the Russian Foundation for Basic Research, grants No. 19-05-00788.

—For a multirate approximation, we have determined the dynamics of rock heating by a magmatic-fluid flow in a flat permeable zone cutting the cratonic lithosphere of the Siberian Platform from a magma chamber at a depth of 50 km to the Earth’s surface. This dynamics is compared with the dynamics of infiltration metasomatism in a three-layer lithosphere section: (1) harzburgitic mantle (depth 50–40 km), (2) crystalline basement (39–7 km), whose composition was simulated by the section of rocks hosting the skarn deposits of the Aldan Shield, and (3) platform cover (6–0 km), with its simplified rock compositions specified on the basis of the rock compositions in the southern and northern parts of the trap area of the Siberian Platform. Numerical modeling of the metasomatic transformation of rocks was performed in a multireservoir flow reactor, using the Selektor software. The initial composition of fluids in a magmatic source varied from highly reduced (water–methane) to ordinary (water–acid) (lg pO2 from –13.0 to –12.0). The obtained balances of the interacting phases show no significant change in the mass of aluminosilicate rocks in the mantle and Earth’s crust sections and a significant loss of their mass under replacement of carbonate and sulfate deposits.

The experimental results presented below shine a light upon the physics of phase transition processes during melting, intensive evaporation, and subsequent explosive destruction of stony meteorites entering the Earth's atmosphere.

Comprehensive studies of mineralogy, fluid and melt inclusions, and gas phase in minerals from a representative collection of peridotite xenoliths that underwent metasomatism and convective partial melting in the mantle wedge beneath Avacha Volcano were used to simulate interactions between mantle wedge material and magmatic fluids of constant and variable compositions at different depths, as well as metasomatic effects of fluids derived from subduction slabs. The obtained virtual dynamic patterns of metasomatic zoning across the mantle wedge show how composition variations of fluids and PT conditions at their sources influence the facies of metasomatized mantle wedge harzburgite. The compositions of the Avacha xenoliths and crustal rodingite from Kamchatka compared with results of physicochemical modeling suggest that eruptions of Avacha Volcano brought metasomatized material of the upper mantle wedge to the surface. The rocks underwent multistage metasomatism along cracks in a relatively narrow temperature range. Such processes are apparently common to seismically deformed permeable lithosphere above magma reservoirs. However, the mineralogical zoning of the Kamchatka crustal rhodingites differs from that in cracked metasomatic peridotite above the sources of magmatic fluids in the mantle wedge beneath the Kamchatka arc.

A quantitative analysis of sublimation of intensely fractured rocks in the mantle wedge was performed using a model of planar fracture channel. The use of dimensionless variables allowed us to analyze the influence of the Nusselt and Sherwood criteria on temperature and variation of the rates of dissolution of minerals and films on fracture walls and estimate both linear and mass sublimation rates. The results of this study predict relatively high rates of major element dissolution and remobilization by flows of magmatic and metamorphic gases over wide temperature range. Physical modeling of this process using natural mantle rock samples confirms the plausibility of the proposed model at least for the case of metamorphic-driven remobilization of elements from gas-liquid inclusions in metasomatized ultramafic rocks. This model provides a satisfactory explanation for the observed local heterophase alterations within ultramafic rocks that have experienced multistage deformation beneath volcanoes of the Kamchatka volcanic front.

A quantitative model describing the dynamics of the process of metasomatic wehrlitization of ultramafics is put forward. It is elaborated for the process taking place in permeable fault zones over a time span of 50 kyr with fluid source depths in the range of 150–50 km at initial temperatures of 1000–1200°C. The possibility of existence of two physical–chemical facies of this process has been demonstrated: one occurs at the level of garnet and the other is at the level of spinel depth facies. Their realization is related to the dependence of the activity of Mg–Ca–Si metasomatism against variation in the composition of low–molecular hydrocarbons in a fluid under conditions of changing T and P in a system.

Software modeling flow multireservoir systems was used to study the dynamics of carbonatization of lithospheric mantle with flows of magmatic fluids directed from a chamber in the upper mantle to the permeable zone, which dissects continental lithosphere. It has been shown that the region of physicochemical conditions of carbonatization in depleted mantle rocks corresponds to the narrow range of the compositions of hypothetical fluids. If the total content of the fluid is similar to 4 wt.% and the contents of SiO2 and Ca are 0.5-0.1 moles, (1) the ratio of the molar fractions of Si to Ca is less than unity; (2) the ratios of molar fractions in the C-H-O system are 1: 2: 3 or 2: 1: 2; (3) -8 < log p(O2) < -11; and (4) CO2 content in the fluid is higher than H2O content by a factor of 1.5-2, and chlorine significantly dominates over fluorine. If the content of the fluid phase is lower and this phase has a lower major-element content by an order of magnitude, the carbonatization becomes stronger as Ca content decreases. (C) 2015, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

A two-dimensional mathematical model is proposed to describe the crystallization of magmatic bodies with roof complicated by apophyses, around which fluidogenic ore deposits could be formed during retrograde boiling of cotectic melts. The most favorable environments for the formation of productive ore-forming systems were numerically simulated Among them are magmatic gas flows and fluid systems of mixed type. Magmatic fluid systems related to the retrograde boiling of cotectic melts in presence of localized sink of volatiles into permeable zones from apophyses in the chamber roof would evolve by two ways: (1) at L 2/h < 1 for intrusion thickness (L 2) and height of apophysis (h), the systems exist as high-temperature quasistationary fluid systems discharging on the surface of volcanic edifices; (2) at L 2/h > 1, the central part of the stock is overcooled and magmatic fluid system ceases to be active after all gas dissolved in the upper half of the stock has been exhausted. Such cases are favorable for the formation of fluid systems of mixed type.

Integrate statistical processing of more than 1000 isotope dates tracing the history of circum-Pacific magmatic ore systems and related mineral deposits in volcanoplutonic belts allows the following inferences: (1) magmatic ore systems (MOS) of volcanic arcs generate monoand polycyclic volcanoplutonic deposits (VPD) with notably different formation times (longevities); (2) the MOS chronology bears periodicity of events in the post-Paleozoic history of the Pacific continental margin; (3) the time series of magmatic ore systems from different circum-Pacific segments show quasi-periodic patterns but the respective metallogenic epochs within the same time intervals have different phases and amplitudes, especially over the past 30 Myr; (4) each mineral type of VPD has its own periodicity; (5) the periodicity in formation times of mono- and polycyclic VPD differs from that in the times of their origin.

The depths of mantle melting zones can be constrained by forward (in terms of physicochemical thermodynamics) or inverse (in terms of equilibrium thermodynamics) modeling. However, there is discrepancy in this respect between fluid-dynamic models of decompression melting in convecting upper mantle and thermodynamic models of basaltic magma sources beneath mid-ocean ridges. We investigate the causes of the mismatch in melting depth predictions with reference to the magmatic systems of the Basin and Range Province in the western margin of North America. The inverse solutions turn out to represent melts from different substrates (depth facies) in the lithospheric mantle, while modeling decompression melting in convecting fertile upper mantle refers to the depths the faults in spreading zones never reach. The discrepancy between forward and inverse solutions may be due to the fact that the respective depth estimates correspond to different levels of the same mantle–crust magmatic systems.