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- Experimental petrology and volcanology, Hydrogeology, Engineering geology Natural Hazards Geodesy and Geophysics Numerical modeling of hydrological and geological processes, Geology, Earth Sciences, Structural Geology, Tectonics, and 11 moreGeodynamics, Analogue Modelling, Volcanology, Raman Spectroscopy, Analogue Modeling, Geobarometry, Amphibole, Magma, Amphiboles, Experimental Petrology, and Granite (Earth Sciences)edit
This paper presents the results of theoretical and experimental investigations of the system rubidium feldspar-quartz-water at a pressure of 1 kbar. It was found that rubidium leucite (RbAlSi2O6) rather than feldspar is stable both in the... more
This paper presents the results of theoretical and experimental investigations of the system rubidium feldspar-quartz-water at a pressure of 1 kbar. It was found that rubidium leucite (RbAlSi2O6) rather than feldspar is stable both in the dry and hydrous systems. Near the eutectic point of the dry system, the liquidas of RbAlSiO4 approaches that of RbAlSi2O6. The latter phase crystallizes owing to the heterogeneity of initial glass obtained at a temperature of 1500°C. The water solubility in RbAlSi3O8 melt is 4.2 ± 0.15 wt % at 1300°C and a water pressure of 1 kbar. The eutectic composition contains 53 ± 2 mol % quartz (recalculated to RbAlSi3O 8 and Si6O12) at a water pressure of 1 kbar. A comparison of the sodium, potassium, and rubidium systems reveals a systematic shift of eutectic composition toward quartz and simultaneous depression of the quartz liquidus. This is related to an increase in the activity of an aluminosilicate phase (leucite in the rubidium system) and a concurre...
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Sodium-silicate glasses with varying water contents were studied by 23Na NMR and 1H NMR spectroscopy. The 23Na NMR spectrum is made up of two Gaussian-Lorentzian components corresponding to rigidly bound and free Na ions. The rigidly... more
Sodium-silicate glasses with varying water contents were studied by 23Na NMR and 1H NMR spectroscopy. The 23Na NMR spectrum is made up of two Gaussian-Lorentzian components corresponding to rigidly bound and free Na ions. The rigidly bound Na is allocated in the disilicate-like domains corresponding to Q3 species of sodium-silicate glasses. Unbound Na is associated with Q2 and Q1 species. It was shown that, during water dissolution, some hydroxyls are incorporated into the disilicate unit of the structure to form NaHSi2O5, while others hydrate silica (Q4species). Our 23Na NMR data are consistent with available data on Q speciation and the proportions of water species in sodium-silicate glasses in the frameworks of a proposed detailed structural scheme of water dissolution.
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The solubility of Pt in CO-CO2 fluid was studied experimentally at P = 50–200 MPa and T = 950 °C. A mixture of MgC2O4 and MgCO3 was used as a source of the fluid. Upon the reaction of the Pt capsule walls and the fluid, a carbonyl of... more
The solubility of Pt in CO-CO2 fluid was studied experimentally at P = 50–200 MPa and T = 950 °C. A mixture of MgC2O4 and MgCO3 was used as a source of the fluid. Upon the reaction of the Pt capsule walls and the fluid, a carbonyl of platinum is formed. The use of the high-temperature quartz ceramics as a fluid trap avoids the effect of mechanical contamination with Pt from the eroded capsule walls. The total content of platinum in the porous fluid traps was measured by the Electrothermal Atomic Absorption (ET-AAS) method. In some experiments, the local analysis of traps was carried out by the Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) method. The composition of fluid in bubbles captured in an albite glass trap was studied by micro-Raman spectroscopy. On the capsule walls and MgO, Pt “whiskers” of submicron diameter were observed, which were formed as a product of carbonyl decomposition during quenching. About 5–15% of carbonyl withstands quenching resul...
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Fresh magma input is necessary attribute of the volcanic activity. Ascending from the depth magma would come into the contact with cooled partially solidified one and may cause its melting (e.g., Izbekov et al., 2004). Viscosity contrast... more
Fresh magma input is necessary attribute of the volcanic activity. Ascending from the depth magma would come into the contact with cooled partially solidified one and may cause its melting (e.g., Izbekov et al., 2004). Viscosity contrast can prevent continuous mixing in the system to keep gravity unstable stratification for some period of time. We consider condition of the convective overturn in the two-layered system composed of the layer of superheated rhyolitic magma overlaid by partially solidified denser counterpart. Temperature at the lower contact of the system is set constant and larger than liquidus one due to contact with more basic and hotter magma. At first problem is treated analytically via analysis of the growth of infinitesimal exponential disturbance of interface in the two layer system with variable viscosity contrast and thicknesses ratio with proper boundary conditions. Time of RTI exponent and melting time for layer half width (at H=200 m, rhyolite material para...
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Large-volume sub-liquidus silicic rocks are erupted in caldera environments with short repose time. Modern in situ isotopic methods have recently permitted analysis of isotopic and trace elemental abundances on micron to smaller scale and... more
Large-volume sub-liquidus silicic rocks are erupted in caldera environments with short repose time. Modern in situ isotopic methods have recently permitted analysis of isotopic and trace elemental abundances on micron to smaller scale and demonstrate strong crystalline heterogeneity. We review recent discoveries of isotopically (O, U-Pb) zircons in large volume ignimbrites (Snake River Plain, Kamchatka, and Iceland). We report results from a long-duration isotope exchange experiment with natural zircon and rutile that was held for 4 months at 850°C and 0.3 kbars in a silica-rich solution doped with 18O, 2H, 7Li and 10B. The length-scales of in-diffusion were examined by depth profiling using time-of-flight (TOF) and Cameca 1270 high sensitivity dynamic SIMS. Rutile and zircon developed ~2 µm and ≤0.13µm Fickian profiles, respectively, suggesting that rutile diffusion coefficients were at ~400 times greater than zircon's, and both are consistent with the wet diffusion coefficient...
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Processes of the intrachamber magma degassing precede degassing in the conduit on the final stages of eruption and may be of no less importance. Appearance of the free fluid phase at the depth can be responsible for intrachamber elements... more
Processes of the intrachamber magma degassing precede degassing in the conduit on the final stages of eruption and may be of no less importance. Appearance of the free fluid phase at the depth can be responsible for intrachamber elements transport, pressure buildup and local magma oxidation. We interpret phenocrysts zonality in Shiveluch andesites in terms of such degassing based on our experimental data. High magnesium andesite of Shiveluch volcano (Kamchatka) was studied at PH2O=2 kbar. Bulk hydrous glass was prepared in the series of operations including hydrothermal reducing of the initially melted oxidized rock powder under hydrothermal conditions and remelting. The Fe2+/Fe3+ ratio in the final hydrous glass was estimated with Mossbauer spectroscopy. It corresponds to fO2 = NNO - NNO+2 in the andesite melt at the experimental PT parameters. Short experiments yield crystals grown from the melt with Fe2+/Fe3+ ratio close to the initial value. Liquidus temperature of amphibole was...
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Abstract We present the results of coupled analogue and numerical models that provide new insights into the relationships between volcanoes and thrusts. The effects of both upper-crustal magma chambers and the load of volcanoes on the... more
Abstract We present the results of coupled analogue and numerical models that provide new insights into the relationships between volcanoes and thrusts. The effects of both upper-crustal magma chambers and the load of volcanoes on the geometry of thrust systems were investigated. Analogue modelling points to a strong influence exerted by a magma chamber on thrust geometry, which, as suggested by the numerical models used to rationalize these results, is related to the stress redistribution around the weak heterogeneity. The low- ...
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This paper reports the results of an experimental investigation of the influence of iron oxidation state in the water-saturated andesite melt of Shiveluch Volcano (Kamchatka) on amphibole composition. Experiments with durations of 2–4 h... more
This paper reports the results of an experimental investigation of the influence of iron oxidation state in the water-saturated andesite melt of Shiveluch Volcano (Kamchatka) on amphibole composition. Experiments with durations of 2–4 h were carried out at a pressure of 2 kbar and temperatures close to the amphibole liquidus (950°C). The degree of iron oxidation (NNO and NNO +
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A new model is proposed for passive degassing from sub-volcanic magma chambers. The water content in stably stratified shallow magma chamber will be equated to its solubility at the upper boundary by convection. Water from a lower layer... more
A new model is proposed for passive degassing from sub-volcanic magma chambers. The water content in stably stratified shallow magma chamber will be equated to its solubility at the upper boundary by convection. Water from a lower layer high in water content can enrich the contact zone of the upper layer and lead to further convective overturn of this boundary
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Research Interests: Geology, Materials Science, Migration, Igneous petrology, Finite Element, and 15 moreMultidisciplinary, Finite Element Analysis, Geometry, Porosity, Porous Media, Power Law, Laboratory experiment, Redistribution, Composite Material, Partial Melting, Magma, EXTRACTION, Plastic deformation, Qualitative Modeling, and Mechanical Property
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"The existence of high-temperature bilayer polymorphs that are isochemical to framework alkaline-earth feldspars suggests the possibility of a similar topology occurring in structures of analogous aluminosilicate melts.... more
"The existence of high-temperature bilayer polymorphs that are isochemical to framework alkaline-earth feldspars suggests the possibility of a similar topology occurring in structures of analogous aluminosilicate melts. The local connectivity of an aluminosilicate network of the bilayer hexagonal anorthite CaAl2Si2O8 type in aluminosilicate glasses and melts is confirmed by the data available in the literature. The presence of bilayer regions in the structure of the materials under investigation leads to a local loss of network connectivity which is similar to that observed upon depolymerization. A model of the viscosity of an anorthite melt is proposed from analyzing the results obtained from calculating the fractions of the normal and bilayer components of the anorthite structure. This model adequately describes the empirical data on the equilibrium constant for the transformation of the normal component into the bilayer component of the structure. The equilibrium constant is determined to be K= 1.608–2640/T, which corresponds to the enthalpy of transformation (+50.6 kJ/mol)."
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We here present results of geochemical investigation and modeling of remelting conditions of rocks that have undergone chemical change in the process of hydrothermal alteration inside of large caldera complexes with high heat flux.... more
We here present results of geochemical investigation and modeling of remelting conditions of rocks that have undergone chemical change in the process of hydrothermal alteration inside of large caldera complexes with high heat flux. Similar conditions exist in rift zones and ...
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Nickel is a strongly compatible element in olivine, and thus fractional crystallization of olivine typically results in a concave-up trend on a Fo–Ni diagram. ‘Ni-enriched’ olivine compositions are considered those that fall above such a... more
Nickel is a strongly compatible element in olivine, and thus fractional crystallization of olivine typically results in a concave-up trend on a Fo–Ni diagram. ‘Ni-enriched’ olivine compositions are considered those that fall above such a crystallization trend. To explain Ni-enriched olivine crystals, we develop a set of theoretical and computational models to describe how primitive olivine phenocrysts from a parent (high-Mg, high-Ni) basalt re-equilibrate with an evolved (low-Mg, low-Ni) melt through diffusion. These models describe the progressive loss of Fo and Ni in olivine cores during protracted diffusion for various crystal shapes and different relative diffusivities for Ni and Fe–Mg. In the case when the diffusivity of Ni is lower than that for Fe–Mg interdiffusion, then olivine phenocrysts affected by protracted diffusion form a concave-down trend that contrasts with the concave-up crystallization trend. Models for different simple geometries show that the concavity of the d...
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Various geodynamic mechanisms can lead to the penetration of siliceous carbonates into the mantle wedge. Their thermal decomposition in the “mantle olivine autoclave” can be a mechanism for the formation of diamond erupted in subduction... more
Various geodynamic mechanisms can lead to the penetration of siliceous carbonates into the mantle wedge. Their thermal decomposition in the “mantle olivine autoclave” can be a mechanism for the formation of diamond erupted in subduction zone of Kamchatka. Using the theory of poro-elasticity, we showed that rapid heating of a mixture of sideritic dolomite and silica at 150-200oC can lead to an increase in pressure by 2-3 GPa. With the initial parameters P = 2 GPa and T = 830oC, the carbonic fluid produced during the reaction would get into the PT stability field of the diamond. The growth of diamond in the PT field of metastable graphite can be enhanced by microparticles of native Ni and Mn formed by the thermal decomposition of gaseous carbonyls. The corresponding abundant micro-inclusions of Ni and Mn are found in Kamchatka diamonds.
Complex core-rim zoning of Mg-Fe-Ni-Ca-Cr-Al-P in high-Mg olivine crystals from a tuff ring of Shiveluch volcano, Kamchatka, enables reconstruction of the entire olivine crystallization history from mantle conditions to eruption.... more
Complex core-rim zoning of Mg-Fe-Ni-Ca-Cr-Al-P in high-Mg olivine crystals from a tuff ring of Shiveluch volcano, Kamchatka, enables reconstruction of the entire olivine crystallization history from mantle conditions to eruption. Bell-shaped Fo and Ni profiles in crystal cores were formed by diffusion after mixing with evolved magma. Diffusion proceeded to the centres of crystals and completely equilibrated Fo and Ni in some crystals. Diffusion times extracted from Fo and Ni core profiles range from 100 to 2000 days. During subsequent mixing with mafic mantle-equilibrated melt, the cores were partially dissolved and overgrown by Fo olivine. Times extracted from Fo and Ni diffusion profiles across the resorption interface between the core and its overgrowth range within 1-10 days, which corresponds to the time of magma ascent to the surface. The overgrowth shows identical smooth Fo-Ni decreasing zoning patterns for all crystals towards the margin, indicating that all crystals shared ...
The initial temperatures, the cooling rates, and the solidification rates existing during the formation of the Zhamanshin and the Boltyshskaia astroblemes are estimated on the basis of modeling these processes in melted impactites and by... more
The initial temperatures, the cooling rates, and the solidification rates existing during the formation of the Zhamanshin and the Boltyshskaia astroblemes are estimated on the basis of modeling these processes in melted impactites and by comparing experimental results with data on petrographic and petrochemical details of melted impactites. It is shown that melted impactites formed under different conditions display different
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Abstract Historical basaltic eruptions of Tolbachik volcano (Kamchatka) are of a medium to high potassic type. The potassic character of magmatism can be attributed to the influence of CO 2 –CO-rich fluid at or near the magma generation... more
Abstract Historical basaltic eruptions of Tolbachik volcano (Kamchatka) are of a medium to high potassic type. The potassic character of magmatism can be attributed to the influence of CO 2 –CO-rich fluid at or near the magma generation depths. Decarbonatization reactions in the mantle under Tolbachik producing a column of the carbonic fluids may be connected with the recent accretion of Kronotsky paleoarc with carbonates dragged under the mantle wedge. With thermodynamic modeling, we show that reduced carbonic fluid at fO 2 4 . This carbonyl is expected to become thermally stable near the magmatic temperatures at pressures above 1 GPa. In the crust, it is predicted to be thermally stable within the PT field of the amphibolite facies. We connect the particles of native Ni and Ag–Pt alloy observed in the volcanic aerosols from the 2012–13 Tolbachik eruption with flushing of the ascending Tolbachik magma with reduced carbonic fluids enriched with PGE and Ni. Native metals may form by the thermal decomposition of the carbonyls and other carbon-bearing compounds dissolved in the fluid.
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A new speciation scheme for melts of the albite composition is proposed. It is assumed that at melting albite decomposes into structural units with tridymite like arrangement of silica-alumina network forming six-membered rings. Alumina... more
A new speciation scheme for melts of the albite composition is proposed. It is assumed that at melting albite decomposes into structural units with tridymite like arrangement of silica-alumina network forming six-membered rings. Alumina clustering is expected with formation of the nepheline like complex with Al:Si ratio equal to unity and pure silica rings. Some feldspar like units survive in the albite melt. Equilibrium is established in accordance with the reaction 3NaAlSi3O8 Na3Al3Si3O12+Si6O12. We suggest to calculate the mole fraction of each unit based on the oxygen basis corresponding to its structure (12 or 8). The constant of the disproportionation reaction as a function of temperature is estimated to fit the melting diagram of the dry Q-Ab binary at ambient pressure: ln(K)=-6.033+ 6841.55/T. The proposed scheme is coherent with reported data on the noble gas solubility and infrared spectra of the albite melt.
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Metamorphic mafic metavolcanic rocks from the upper stream of Krutogorova river (SW Kamchatka) are characterized geochemically. In accordance with presented data these mafic rocks along with Ni ore-bearing rocks of the... more
Metamorphic mafic metavolcanic rocks from the upper stream of Krutogorova river (SW Kamchatka) are characterized geochemically. In accordance with presented data these mafic rocks along with Ni ore-bearing rocks of the kortlandite-gabbronorite formation from Kuvalorog (Kamchatka) had been formed at the melting of the undepleted mantle during adiabatic decompression (without involvement of the subductive fluids and melts). Relatively large formation depth (P=8 kbar) of the small kortlandite-gabbro-norite inrusions is confirmed by means of our new amphibole barometer, formation depth of the subvolcanic sills of Krutogorova river is substantially smaller (P=2-4 kbar). Physical mechanism of the primitive mantle melts formation is discussed based on the results of the simplified numerical modelling of the subduction initiation and slab delamination. Geochemical and numerical data stay for the formation of the picrobasaltic magmas in the ascending upper mantle flows caused by the complica...
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Melting phase relations were studied for a hawaiitic composition with 2.4±0.1 wt % water under a pressure of 600 bar and oxygen fugacity near the Ni–NiO buffer. These conditions correspond to the degassing and eruption of Etna Volcano,... more
Melting phase relations were studied for a hawaiitic composition with 2.4±0.1 wt % water under a pressure of 600 bar and oxygen fugacity near the Ni–NiO buffer. These conditions correspond to the degassing and eruption of Etna Volcano, Sicily. The experimental liquidus temperatures of olivine ( 1120°C ) and clinopyroxene (1105°C) are in agreement with the values calculated by the MELTS software package. The growth rates of olivine and clinopyroxene were estimated by the quench method using forsterite and diopside seeds. At an undercooling of ΔT= 25±5 K, lathlike clinopyroxene grew at a rate of (2.0–2.5)×10–5cm/s and contained 6.5–8.5 wt % Al2O3. Under similar conditions, diopside seeds are evenly overgrown at an order of magnitude lower rate, (2–3)×10–6cm/s. At ΔT ≈ 5K (T= 1100°C), diopside seeds are evenly overgrown with the formation of growth steps on the surface of crystals. The growth rate of olivine is low, 7×10–7cm/s at 1075°C (ΔT= 45±5 K) . This is consistent with the small amount of olivine forming during cooling of hydrous hawaiite melt calculated by the MELTS program.
Research Interests: Geology and Geochemistry
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Research Interests: Geology, Geochemistry, Geophysics, Rheology, Finite Element, and 13 moreDamage Mechanics, Strain Rate, Tectonophysics, Power Law, Laboratory experiment, Partial Melting, Fluid flow, Time Dependent, Strain localization, Numerical Model, Constitutive model, Theoretical Model, and Numerical Calculation
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The common concept of thermal convection in a magma chamber cooling from above involves only buoyancy due to thermal expansion of the melt neglecting the effect of a solid-liquid phase transition. Whereas, in a crystallizing magma at... more
The common concept of thermal convection in a magma chamber cooling from above involves only buoyancy due to thermal expansion of the melt neglecting the effect of a solid-liquid phase transition. Whereas, in a crystallizing magma at equilibrium, the total effect of crystal fractionation and cooling on the melt density is often negative, melt can become denser only due to
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ABSTRACT A new model is proposed to numerically simulate transfer of melt between microscopic pores and macroscopic veins in a deforming porous matrix. Matrix rheology is assumed to be visco-elastic. Darcy flow of porous melt through the... more
ABSTRACT A new model is proposed to numerically simulate transfer of melt between microscopic pores and macroscopic veins in a deforming porous matrix. Matrix rheology is assumed to be visco-elastic. Darcy flow of porous melt through the matrix is calculated in accord with the theory of poroelasticity. Veins of melt are described separately. The model is realized using a code for a 2-D rectangle that is deformed at a constant strain rate. We reproduce in 2-D the main analytical results derived by Sleep (1988) but add calculations concerning the flow and local compaction processes around veins with different inclinations to the maximum (compressive) deviatoric stress. Inclusions perpendicular to σ1 tend to close while those parallel to σ1 tend to grow. Surrounding regions either compact or dilate and inclined veins propagate parallel to σ1. The incremental porosity decreases exponentially with distance from the vein walls by a factor equal to the compaction length. Local redistribution of melt from microscopic pores to macroscopic veins strongly enhances melt segregation into the vein networks which can lead to bodies sufficiently massive to become buoyant.
Research Interests: Geology, Geochemistry, Geophysics, Flow, Generation, and 5 moreRock, Deformation, Mantle, Magma, and Dikes
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ABSTRACT Water incorporation in the natural and experimental nepheline crystals was studied with IR methods. Synthetic nepheline was produced at PH2O=2 kbar. Water content in nepheline was measured with SIMS method comprising 0.33 wt.% in... more
ABSTRACT Water incorporation in the natural and experimental nepheline crystals was studied with IR methods. Synthetic nepheline was produced at PH2O=2 kbar. Water content in nepheline was measured with SIMS method comprising 0.33 wt.% in experimental crystal. We estimate the integral molar absorption coefficient K1 = 4500 \pm 600.0 l/mol cm^2 in the section inclined on 45^o to c-axis. The integral molar absorption coefficient for synthetic nepheline in the section perpendicular to c-axis was found to be K2 = 6000 \pm 500 l/mol cm^2.
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Cooling of magmatic intrusions within the upper crust is associated with convection and crystallization. A one-dimensional crystallization model, with sedimentation, in the upper boundary layer is presented. The sedimentation velocity is... more
Cooling of magmatic intrusions within the upper crust is associated with convection and crystallization. A one-dimensional crystallization model, with sedimentation, in the upper boundary layer is presented. The sedimentation velocity is assumed to be constant. A two-component, two-phase system is considered, assuming thermodynamic equilibrium. A steady-state solution for the system of equations of conservation of energy and mass is found.
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As the magma ascends from its depth of generation to the surface, it is often stored in a series of chambers along the way. The rheological contrast between the viscous magma in the magmatic chambers and the surrounding rocks disturbed... more
As the magma ascends from its depth of generation to the surface, it is often stored in a series of chambers along the way. The rheological contrast between the viscous magma in the magmatic chambers and the surrounding rocks disturbed the stress field which can give rise to various modes of rock failure at magmatic pressures less than the lithostatic stress, leading to an eruption. Different modes of mechanical failure of the chamber walls are considered depending on the geometry and the sign the relative pressure. Relaxation of viscous stress around magmatic chambers, which is important on the time scale of weeks to months is considered in the analysis of stability with application to both large and extra‐large magmatic chambers such as Yellowstone. The effects of a strong deep CO2 flux in Yellowstone are considered in detail. The analysis shows that variations in the flow rate around the observed mean value of 40 kg/m2/yr in the hydrothermally active areas can change the composition of the magma for several hundred thousand years, and cause periodic uplift and subsidence of the caldera surface with a period of several decades.