Basal freeze-on generates complex ice-sheet stratigraphy

Large, plume-like internal ice-layer-structures have been observed in radar images from both Antarctica and Greenland, rising from the ice-sheet base to up to half of the ice thickness. Their origins are not yet understood. Here, we simulate their genesis by basal freeze-on using numerical ice-flow...

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Bibliographic Details
Published in:Nature communications 2018-11, Vol.9 (1), p.4669-13, Article 4669
Main Authors: Leysinger Vieli, G. J.-M. C., Martín, C., Hindmarsh, R. C. A., Lüthi, M. P.
Format: Article
Language:English
Subjects:
639/766/189
704/106/125
Computer simulation
Fluctuations
Flux
Heat
Humanities and Social Sciences
Hypotheses
Ice
Ice cover
Ice sheets
Ice thickness
Mathematical models
multidisciplinary
Radar
Radar imaging
Science
Science (multidisciplinary)
Stratigraphy
Structure-function relationships
Topography
Water availability
Water flow
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Summary:Large, plume-like internal ice-layer-structures have been observed in radar images from both Antarctica and Greenland, rising from the ice-sheet base to up to half of the ice thickness. Their origins are not yet understood. Here, we simulate their genesis by basal freeze-on using numerical ice-flow modelling and analyse the transient evolution of the emerging ice-plume and the surrounding ice-layer structure as a function of both freeze-on rate and ice flux. We find good agreement between radar observations, modelled ice-plume geometry and internal layer structure, and further show that plume height relates primarily to ice-flux and only secondarily to freeze-on. An in-depth analysis, performed for Northern Greenland of observed spatial plume distribution related to ice flow, basal topography and water availability supports our findings regarding ice flux and suggests freeze-on is controlled by ascending subglacial water flow. Our results imply that widespread basal freeze-on strongly affects ice stratigraphy and consequently ice-core interpretations. Subsurface ice-sheet radar images reveal large plume-shaped bodies rising from the base, with their origin not yet understood. Here, the authors show that freeze-on of water at the ice-sheet base combined with ice-flux explains the vertical extent, shape and structure of the observed plumes.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-018-07083-3