Termální konvekce s inerciálními částicemi a pohyblivým fázovým rozhraním

• Thesis title in Czech: Termální konvekce s inerciálními částicemi a pohyblivým fázovým rozhraním
• Thesis title in English: Particle-laden convective flow with a moving phase boundary
• Key words: termální konvekce|magma|krystalizace
• English key words: thermal convection|magma|crystallization
• Academic year of topic announcement: 2024/2025
• Thesis type: dissertation
• Department: Department of Geophysics (32-KG)
• Supervisor: RNDr. Vojtěch Patočka, Ph.D.
• Advisors: doc. RNDr. Ondřej Souček, Ph.D.

Guidelines

Igneous rocks are important sources of rare earth elements. Much effort has been invested in inferring magmatic processes from igneous textures (for a review, see Jerram et al., 2018), but even basic aspects of the solidification process remain poorly understood: it is not clear whether crystallization proceeds mainly along the walls of intrusions (in-situ), or whether newly forming crystals are stirred by convecting magma before settling (e.g., Holness et al., 2017, 2022). Despite this knowledge gap, physical models of the underlying particle-laden flow are simplistic, with the most common model being the Stokes' law, while the petrology of magmatic intrusions has been subject to numerous studies. The student will build a paramatrized as well as direct numerical model of solidifying magmatic reservoir that accounts for non-trivial particle dynamics, and analyze detectable signatures that convection leaves in fully solidified bodies.

In first stage of the project, the student will construct a parametrized model of a cooling magma chamber (building on the work of Jarvis and Woods, 1994), in which the nucleation and growth of crystals will be governed by experimentally determined kinetic laws (e.g., Hort, 1997), and particle dynamics will be approximated by the settling law from Patočka et al., 2022. The boundary conditions will be determined by solving the 1D heat equation in the surrounding host rock (e.g., Annen et al., 2002). In the second stage, a direct numerical model of the solidification process will be constructed by modifying an already existing geodynamic code (CH4 or StagYY, see Calzavarini, 2019, and Tackley, 2008). Direct numerical model will allow the student to (i) assess the role of the viscosity increase with increasing solid fraction, (ii) investigate the role of latent heat release on the convective vigor of the fluid, and (iii) study the re-entrainment of crystals from the surface of an already accumulated sediment. Although in a different parameter range, the resulting numerical tool has potential applications also in the study of other particle-laden convective flows with phase change at boundaries, e.g. in the study of a boiling water body with an ice cover that is subject to low atmospheric pressure (see Brož et al., 2023).

References

Annen, C., Sparks, R.S.J., 2002. Effects of repetitive emplacement of basaltic intrusions on thermal evolution and melt generation in the crust, Earth and Planetary Science Letters, Volume 203, Issues 3–4.

Brož, P., Krýza, O., Patočka, V., Pěnkavová, V., Conway, S. J., Mazzini, A., et al., 2023. Volumetric changes of mud on Mars: Evidence from laboratory simulations. Journal of Geophysical Research: Planets, 128, e2023JE007950.

Calzavarini, E., 2019. Eulerian–Lagrangian fluid dynamics platform: the ch4-project. Softw. Impacts 1, 100002.

Jarvis, R.A., Woods, A.W., 1994. The nucleation, growth and settling of crystals from a turbulently convecting fluid. J. Fluid Mech. 273, 83–107.

Jerram, D.A., Dobson, K.J., Morgan, D.J., Pankhurst, M.J., 2018. Chapter 8 - the petrogenesis of magmatic systems: using igneous textures to understand magmatic processes. In: Burchardt, S. (Ed.), Volcanic and Igneous Plumbing Systems. Elsevier, pp. 191–229.

Holness, M.B., Farr, R., Neufeld, J.A., 2017. Crystal settling and convection in the Shiant Isles Main Sill. Contrib. Mineral. Petrol. 172, 7.

Holness, M.B., Nicoli, G., Rust, A., Neufeld, J., 2022. The Microstructural Record of Convection in the Little Minch Sill Complex, Scotland, Journal of Petrology, Volume 63, Issue 11.

Hort, M., 1997. Cooling and crystallization in sheet-like magma bodies revisited J. Volcanol. Geotherm. Res., 76 (1997), pp. 297-317, 1.

Patočka, V., Tosi, N. & Calzavarini, E. (2022). Residence time of inertial particles in 3D thermal convection: implications for magma reservoirs. Earth and Planetary Science Letters 591, 117622.

Tackley, P.J., 2008. Modelling compressible mantle convection with large viscosity contrasts in a three-dimensional spherical shell using the Yin-Yang grid, Phys. Earth planet. Inter., 171(1–4, SI), 7–18.