Crystallization of Cpx in the Ab-Di System Under the Oscillating Temperature: Contrast Dynamic Modes at Different Periods of Oscillation

Simakin, A. G.; Devyatova, V. N.; Некрасов, А. Н.

doi:10.1007/978-3-030-42859-4_5

Cited by 6 publications

(2 citation statements)

References 26 publications

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“…As with flushing, CO 2 and H 2 O are decoupled due to their contrasting diffusivities. The control of the inter-bubble distance on CO 2 equilibration is very similar to the condition of disequilibrium Cpx growth in the Ab-Di-H 2 O system [Simakin et al, 2020]. Non-equilibrium hopper morphology of the crystal rim develops during quenching, when inter-crystalline distances exceed 5-8 µm.…”

Section: Discussionmentioning

confidence: 64%

Theoretical and Experimental Modeling of Local Scale CO2 Flushing of Hydrous Rhyolitic Magma

Simakin,

Devyatova,

Shiryaev

2023

Russian Journal of Earth Sciences

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Flushing of hydrous silicic magmas with crustal carbonic fluid may be an important factor controlling the dynamics of rhyolitic eruptions. We present combined theoretical and experimental study of the interaction of carbonic fluid with a hydrous silicic melt. The process of diffusional equilibration of a CO2 bubble with a silicic melt was simulated numerically in the spherical shell approximation. The rapid water transfer from the melt to the bubble is followed by a slower diffusion of CO2 into the melt. The water distribution in the melt becomes almost uniform over a period proportional to the diffusional unit of time 0.14τw, determined by the initial inter-bubble distance W equal the distance between neighbor bubbles centers and the water diffusion coefficient Dw in the melt (τw = W 2/Dw), while the CO2 distribution remains strongly contrasting and the melt remains undersaturated in CO2. This process was modelled experimentally with a hydrous albite melt at P = 200MPa and T = 950–1000 °C. In the first series of experiments at T = 950◦C, a glass powder was filled with pure CO2 at the beginning of the experiment, forming numerous bubbles at the run temperature. Micro-FTIR measurements showed that after 40 minutes the water content in the melt decreased from 4.9 down to 1.8 wt. % with the maximum CO2 content of 500 ppm (below saturation). After 4 hours, the crystallinity increased to 85%, and almost all of the fluid bubbles escaped. The second series of experiments CO2 interacted with a 2 mm high column of hydrous albite melt. Diffusion profiles in the quenched glass were measured using EMPA (H2O) and micro-FTIR (CO2 and H2O). The estimated diffusion coefficients in the melt for H2O (1.1 × 10−6 cm2 /s) and CO2 (1.5 × 10−7 cm2 /s) are consistent with published data. Scaling analysis predicts that in the nature, after the influx of CO2 bubbles a few millimeters in size, the maximum dehydration of rhyolitic magma with viscosity near 105 Pa s without a significant increase in CO2 content occurs after 1–30 days, i.e. a period compatible with the minimum duration of pre-eruption processes in the magma chamber.

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Section: Discussionmentioning

confidence: 64%

Theoretical and Experimental Modeling of Local Scale CO2 Flushing of Hydrous Rhyolitic Magma

Simakin,

Devyatova,

Shiryaev

2023

Russian Journal of Earth Sciences

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“…In addition to simple recharging, intra-chamber vesiculation may be a factor increasing the magma pressure in the chamber to a level sufficient to cause failure of the chamber roof and onset of an explosive eruption. The carbonic fluid transfers heat and dissolved components, thereby affecting the heat budget of the magma and its composition [Simakin and Ghassemi, 2018].…”

Section: Introductionmentioning

confidence: 99%

Theoretical and experimental modeling of local scale CO2 flushing of hydrous rhyolitic magma

Simakin¹,

Devyatova²,

Shiryaev³

2023

Preprint

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Flushing of hydrous silicic magmas with crustal carbonic fluid may be an important factor controlling the explosiveness of rhyolitic eruptions. We present combined theoretical and experimental study of the interaction of carbonic fluid with a hydrous silicic melt. The process of diffusional equilibration of a CO2 bubble with a silicic melt was simulated numerically in the spherical approximation. The rapid water transfer from the melt to the bubble is followed by a slower diffusion of CO2 into the melt. The water distribution becomes almost uniform over a period proportional to the diffusional unit of time 0.14W, determined by the initial inter-bubble distance W and the water diffusion coefficient Dw (W =W2/Dw), while the CO2 distribution remains strongly contrasting. This process was modelled experimentally with a hydrous albite melt at P=200 MPa and T=950-1000oC. In the first series of experiments at T=950oC, a glass powder was filled with pure CO2 at the beginning of the experiment, forming numerous bubbles at the run temperature. Micro-FTIR measurements showed that after 40 minutes the water content decreased from 4.9 down to 1.8 wt.% with the maximum CO2 content 500 ppm. After 4 hours, the crystallinity increases to 85%, and the fluid bubbles almost disappear. The second series of experiments CO2 interacted with a 2 mm high column of hydrous albite melt. Diffusion profiles in the quenched glass were measured using EMPA (H2O) and micro-FTIR (CO2 and H2O). The estimated diffusion coefficients for H2O (1.1×10-6 cm2/s) and CO2 (1.5e×10-7 cm2/s) are consistent with published data. Scaling analysis predicts that in natural environment the homogenization of water in rhyolitic magma after an influx of CO2 bubbles few millimeters in size lasts for 1-30 days, i.e. a period compatible with pre-eruptive processes in a magma chamber.

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Crystal Size Distribution as a Key to Understanding Protocumulus Evolution in Layered Intrusions: Experiments, Calculations, and Practice of CSD Extraction

Sobolev,

Ariskin,

Nikolaev

et al. 2023

Petrology

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Crystallization of Cpx in the Ab-Di System Under the Oscillating Temperature: Contrast Dynamic Modes at Different Periods of Oscillation

Cited by 6 publications

References 26 publications

Theoretical and Experimental Modeling of Local Scale CO2 Flushing of Hydrous Rhyolitic Magma

Theoretical and Experimental Modeling of Local Scale CO2 Flushing of Hydrous Rhyolitic Magma

Theoretical and experimental modeling of local scale CO2 flushing of hydrous rhyolitic magma

Crystal Size Distribution as a Key to Understanding Protocumulus Evolution in Layered Intrusions: Experiments, Calculations, and Practice of CSD Extraction

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