Entropic Bounds for Multi-Scale and Multi-Physics Coupling in Earth Sciences

Regenauer‐Lieb, Klaus; Karrech, Ali; Chua, Hui Tong; Poulet, Thomas; Veveakis, Manolis; Wellmann, Florian; Liu, Jie; Schrank, Christoph; Gaede, Oliver; Trefry, M. G.; Ord, Alison; Hobbs, B. E.; Metcalfe, Guy; Lester, Daniel

doi:10.1007/978-3-642-40154-1_17

Cited by 7 publications

(7 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is achieved by expanding the area of investigation until the feature of interest, in our case porosity, stops varying. We borrow this homogenization approach from the calculation of material properties, like the elastic moduli, where the RVE provides a minimum sample size that can accurately describe the property (Hill, ; Regenauer‐Lieb et al, ).…”

Section: Methodsmentioning

confidence: 99%

Dynamic Recrystallization Can Produce Porosity in Shear Zones

Gilgannon

Poulet

Berger

et al. 2020

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

Creep cavities are increasingly recognized as an important syn-kinematic feature of shear zones, but much about this porosity needs investigation. Largely, observations of creep cavities are restricted to very fine grained mature ultramylonites, and it is unclear when they developed during deformation. Specifically, a question that needs testing is should grain size reduction during deformation produce creep cavities? To this end, we have reanalyzed the microstructure of a large shear strain laboratory experiment that captures grain size change by dynamic recrystallization during mylonitization. We find that the experiment does contain creep cavities. Using a combination of scanning electron microscopy and spatial point statistics, we show that creep cavities emerge with, and because of, subgrain rotation recrystallization during ultramylonite formation. As dynamic recrystallization is ubiquitous in natural shear zones, this observation has important implications for the interpretation of concepts such as the Goetze criterion, paleopiezometery, and phase mixing. Plain Language SummaryAt great depths inside the Earth, rocks called mylonites slowly deform and accommodate tectonic forces. Generally, these rocks are considered to have no porosity because the pressure they experience is very large. However, it is frequently documented that these mylonites focus the transport of mass, both fluid and solid, through the crust. This implies that mylonites host a permeable porosity. To better understand this paradox, we reanalyzed an old laboratory experiment that documented the formation of a mylonite. We showed that a porosity, known as creep cavities, forms synchronously with the mylonite. This is an important experimental finding because it suggests that creep cavities are a fundamental feature of mylonites. Our results showcase a rare snapshot into the dynamics of rocks important for tectonics and advance larger questions about their transport properties.

show abstract

Section: Methodsmentioning

confidence: 99%

Dynamic Recrystallization Can Produce Porosity in Shear Zones

Gilgannon

Poulet

Berger

et al. 2020

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…This is achieved by expanding the area of investigation until the feature of interest, in our case porosity, stops varying. We borrow this homogenisation approach from the calculation of material properties, like the elastic moduli, where the RVE provides a minimum sample size that can accurately describe the property (Hill, 1963;Regenauer-Lieb et al, 2014).…”

Section: Defining a Representative Microstructurementioning

confidence: 99%

Dynamic recrystallisation can produce porosity in shear zones

Gilgannon¹,

Poulet²,

Berger³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Creep cavities are increasingly recognised as an important syn-kinematic feature of shear zones but much about this porosity needs investigation. Largely, observations of creep cavities are restricted to very fine grained mature ultramylonites and it is unclear when they developed during deformation. Specifically, a question that needs testing is; should grain-size reduction during deformation produce creep cavities? To this end, we have reanalysed the microstructure of a large shear strain laboratory experiment that captures grain-size change by dynamic recrystallisation during mylonitisation. We find that the experiment does contain creep cavities. Using a combination of scanning electron microscopy and spatial point statistics, we show that creep cavities emerge with, and because of, sub-grain rotation recrystallisation during ultramylonite formation. As dynamic recrystallisation is ubiquitous in natural shear zones, this observation has important implications for the interpretation of concepts such as the Goetze criterion, palaeopiezometery and phase mixing.

show abstract

“…The concept of upper and lower bounds of elasto-plastic work is then turned into an upper/lower bound of entropy production (Regenauer-Lieb et al, 2010) for the elasto-visco-plastic deformation. The assessment of uncertainty of the solution due to the time dependence of the problem can be obtained from numerical studies where thermodynamic flux boundary conditions provide a maximum of entropy production and thermodynamic force boundary conditions yield a minimum of entropy production (Regenauer-Lieb et al, 2014). The incorporation of the entropic evolution can be expressed through the time dependence in the entropic evolution equation.…”

Section: Relaxing Isothermal Conditionsmentioning

confidence: 99%

Entropic Limit Analysis Applied to Radial Cavity Expansion Problems

Regenauer‐Lieb

2018

Front. Mater.

Self Cite

View full text Add to dashboard Cite

Analytical solutions of limit analysis design for the simple problem of plane strain expansion of a cylindrical cavity are derived and generalized into entropic extremum principles that allow a fundamental assessment of coupled thermal/hydro/mechanical/chemical (THMC) material instabilities and their effect on the upper and lower bounds of dissipation. The proposed approach integrates a thermodynamically based estimation of uncertainties in coupled deformation processes and an identification of the intrinsic material length/time scales that appear as energy eigenstates of the localization problem. Analytical limit analysis design solutions of the cavity expansion are obtained and upper and lower bound estimates are shown to coincide. This provides a robust framework for adding multiphysics feedbacks. Isothermal conditions are first relaxed and the feedback between shear heating, thermal weakening and thermal diffusion is analyzed. Then the analysis is extended to a full range of THMC localization phenomena which are described with a cascade of characteristic time/length scales derived from instabilities in the governing reaction-diffusion equations. Entropic uncertainties are estimated by alternating system constraints between thermodynamic flux and thermodynamic force on the boundaries.

show abstract

Entropic Bounds for Multi-Scale and Multi-Physics Coupling in Earth Sciences

Cited by 7 publications

References 16 publications

Dynamic Recrystallization Can Produce Porosity in Shear Zones

Dynamic Recrystallization Can Produce Porosity in Shear Zones

Dynamic recrystallisation can produce porosity in shear zones

Entropic Limit Analysis Applied to Radial Cavity Expansion Problems

Contact Info

Product

Resources

About