title: Converging flow and anisotropy cause large-scale folding in Greenland's ice sheet.
abstract: The increasing catalogue of high-quality ice-penetrating radar data provides a unique insight in the internal layering architecture of the Greenland ice sheet. The stratigraphy, an indicator of past deformation, highlights irregularities in ice flow and reveals large perturbations without obvious links to bedrock shape. In this work, to establish a new conceptual model for the formation process, we analysed the radar data at the onset of the Petermann Glacier, North Greenland, and created a three-dimensional model of several distinct stratigraphic layers. We demonstrate that the dominant structures are cylindrical folds sub-parallel to the ice flow. By numerical modelling, we show that these folds can be formed by lateral compression of mechanically anisotropic ice, while a general viscosity contrast between layers would not lead to folding for the same boundary conditions. We conclude that the folds primarily form by converging flow as the mechanically anisotropic ice is channelled towards the glacier.
authors.affiliation: Mineralogy and Geodynamics, Department of Geosciences, Eberhard Karls University Tübingen, Wilhelmstrasse 56, 72074 Tübingen, Germany.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Bons
authors.affiliation: Glaciology Department, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Jansen
authors.affiliation: Mineralogy and Geodynamics, Department of Geosciences, Eberhard Karls University Tübingen, Wilhelmstrasse 56, 72074 Tübingen, Germany.
authors.forename: Felicitas
authors.initials: F
authors.lastname: Mundel
authors.affiliation: Paleoanthropology, Senckenberg Center for Human Evolution and Paleoenvironment, Eberhard Karls University Tübingen, Rümelinstrasse 23, 72070 Tübingen, Germany.
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Bauer
authors.affiliation: Glaciology Department, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Binder
authors.affiliation: Glaciology Department, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.|Department of Geosciences, University of Bremen, PO Box 330 440, Bremen 28334, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Eisen
authors.affiliation: Centre for Exploration Targeting, School of Earth and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, Crawley, Western Australia 6009, Australia.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Jessell
authors.affiliation: Mineralogy and Geodynamics, Department of Geosciences, Eberhard Karls University Tübingen, Wilhelmstrasse 56, 72074 Tübingen, Germany.|Glaciology Department, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Maria-Gema
authors.initials: MG
authors.lastname: Llorens
authors.affiliation: Mineralogy and Geodynamics, Department of Geosciences, Eberhard Karls University Tübingen, Wilhelmstrasse 56, 72074 Tübingen, Germany.|Glaciology Department, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Steinbach
authors.affiliation: Glaciology Department, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Steinhage
authors.affiliation: Mineralogy and Geodynamics, Department of Geosciences, Eberhard Karls University Tübingen, Wilhelmstrasse 56, 72074 Tübingen, Germany.|Glaciology Department, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Alten Hafen 26, 27568 Bremerhaven, Germany.
authors.forename: Ilka
authors.initials: I
authors.lastname: Weikusat