Partial melting in polycrystalline ice: pathways identified in 3D neutron tomographic images

Wilson, Christopher J. L.; Peternell, Mark; Salvemini, Filomena; Luzin, Vladimir; Enzmann, Frieder; Moravcova, Olga; Hunter, Nicholas J. R.

In frozen cylinders composed of deuterium ice (inline-formulaTm+3.8inline-formulaC) and 10 % water ice (inline-formulaTm 0inline-formulaC), it is possible to track melt pathways produced by increasing the temperature during deformation. Raising the temperature to inline-formula+2inline-formulaC produces water (Hinline-formula2O) which combines with the Dinline-formula2O ice to form mixtures of HDO. As a consequence of deformation, HDO and Hinline-formula2O meltwater are expelled along conjugate shear bands and as compactional melt segregations. Melt segregations are also associated with high-porosity networks related to the location of transient reaction fronts where the passage of melt-enriched fluids is controlled by the localized ductile yielding and lowering of the effective viscosity. Accompanying the softening, the meltwater also changes and weakens the crystallographic fabric development of the ice. Our observations suggest meltwater-enriched compaction and shear band initiation provide instabilities and the driving force for an enhancement of permeability in terrestrial ice sheets and glaciers.

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Wilson, Christopher J. L. / Peternell, Mark / Salvemini, Filomena / et al: Partial melting in polycrystalline ice: pathways identified in 3D neutron tomographic images. 2024. Copernicus Publications.

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