Articles | Volume 19, issue 10
https://doi.org/10.5194/tc-19-5095-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-19-5095-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
27 Oct 2025
Research article |
| 27 Oct 2025
| 27 Oct 2025
Folding due to anisotropy in ice, from drill-core-scale cloudy bands to km-scale internal reflection horizons
Department of Geosciences, Tübingen University, Tübingen, Germany
China University of Geosciences (Beijing), Beijing, China
Yuanbang Hu
Department of Geosciences, Tübingen University, Tübingen, Germany
Center for High Pressure Science and Technology Advanced Research, Beijing, China
M.-Gema Llorens
Geosciences Barcelona GEO3BCN-CSIC, Barcelona, Spain
Steven Franke
Department of Geosciences, Tübingen University, Tübingen, Germany
Nicolas Stoll
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Department of Environmental Sciences, Informatics and Statistics, Ca’Foscari University of Venice, Venice, Italy
Ilka Weikusat
Department of Geosciences, Tübingen University, Tübingen, Germany
Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
Julien Westhoff
Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
Department of Geosciences, Tübingen University, Tübingen, Germany
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Nicolas Stoll, Julien Westhoff, Pascal Bohleber, Anders Svensson, Dorthe Dahl-Jensen, Carlo Barbante, and Ilka Weikusat
The Cryosphere, 17, 2021–2043, https://doi.org/10.5194/tc-17-2021-2023, https://doi.org/10.5194/tc-17-2021-2023, 2023
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Impurities in polar ice play a role regarding its climate signal and internal deformation. We bridge different scales using different methods to investigate ice from the Last Glacial Period derived from the EGRIP ice core in Greenland. We characterise different types of cloudy bands, i.e. frequently occurring milky layers in the ice, and analyse their chemistry with Raman spectroscopy and 2D imaging. We derive new insights into impurity localisation and deposition conditions.
Ole Zeising, Tamara Annina Gerber, Olaf Eisen, M. Reza Ershadi, Nicolas Stoll, Ilka Weikusat, and Angelika Humbert
The Cryosphere, 17, 1097–1105, https://doi.org/10.5194/tc-17-1097-2023, https://doi.org/10.5194/tc-17-1097-2023, 2023
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The flow of glaciers and ice streams is influenced by crystal fabric orientation. Besides sparse ice cores, these can be investigated by radar measurements. Here, we present an improved method which allows us to infer the horizontal fabric asymmetry using polarimetric phase-sensitive radar data. A validation of the method on a deep ice core from the Greenland Ice Sheet shows an excellent agreement, which is a large improvement over previously used methods.
Steven Franke, Alfons Eckstaller, Tim Heitland, Thomas Schaefer, and Jölund Asseng
Polarforschung, 90, 65–79, https://doi.org/10.5194/polf-90-65-2022, https://doi.org/10.5194/polf-90-65-2022, 2022
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For over 45 years, teams composed of scientists, technicians, doctors, and cooks have been wintering in Antarctica in the service of German Antarctic research. They thus form a cornerstone of long-term scientific measurements in this remote and unique place with regard to future scientific investigations. In this article, we highlight the research being conducted at the permanently crewed Neumayer Station III and its predecessors and the role of the overwinterers in this research endeavour.
Till Sachau, Haibin Yang, Justin Lang, Paul D. Bons, and Louis Moresi
Geosci. Model Dev., 15, 8749–8764, https://doi.org/10.5194/gmd-15-8749-2022, https://doi.org/10.5194/gmd-15-8749-2022, 2022
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Knowledge of the internal structures of the major continental ice sheets is improving, thanks to new investigative techniques. These structures are an essential indication of the flow behavior and dynamics of ice transport, which in turn is important for understanding the actual impact of the vast amounts of water trapped in continental ice sheets on global sea-level rise. The software studied here is specifically designed to simulate such structures and their evolution.
Vjeran Višnjević, Reinhard Drews, Clemens Schannwell, Inka Koch, Steven Franke, Daniela Jansen, and Olaf Eisen
The Cryosphere, 16, 4763–4777, https://doi.org/10.5194/tc-16-4763-2022, https://doi.org/10.5194/tc-16-4763-2022, 2022
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Alfons Eckstaller, Jölund Asseng, Erich Lippmann, and Steven Franke
Geosci. Instrum. Method. Data Syst., 11, 235–245, https://doi.org/10.5194/gi-11-235-2022, https://doi.org/10.5194/gi-11-235-2022, 2022
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We present a mobile and self-sufficient seismometer station concept for operation in polar regions. The energy supply can be adapted as required using the modular cascading of battery boxes, wind generators, solar cells, or backup batteries, which enables optimum use of limited resources. Our system concept is not limited to the applications using seismological stations. It is a suitable system for managing the power supply of all types of self-sufficient measuring systems in polar regions.
Maria-Gema Llorens, Albert Griera, Paul D. Bons, Ilka Weikusat, David J. Prior, Enrique Gomez-Rivas, Tamara de Riese, Ivone Jimenez-Munt, Daniel García-Castellanos, and Ricardo A. Lebensohn
The Cryosphere, 16, 2009–2024, https://doi.org/10.5194/tc-16-2009-2022, https://doi.org/10.5194/tc-16-2009-2022, 2022
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Polar ice is formed by ice crystals, which form fabrics that are utilised to interpret how ice sheets flow. It is unclear whether fabrics result from the current flow regime or if they are inherited. To understand the extent to which ice crystals can be reoriented when ice flow conditions change, we simulate and evaluate multi-stage ice flow scenarios according to natural cases. We find that second deformation regimes normally overprint inherited fabrics, with a range of transitional fabrics.
Julien Westhoff, Giulia Sinnl, Anders Svensson, Johannes Freitag, Helle Astrid Kjær, Paul Vallelonga, Bo Vinther, Sepp Kipfstuhl, Dorthe Dahl-Jensen, and Ilka Weikusat
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We present a melt event record from an ice core from central Greenland, which covers the past 10 000 years. Our record displays warm summer events, which can be used to enhance our understanding of the past climate. We compare our data to anomalies in tree ring width, which also represents summer temperatures, and find a good correlation. Furthermore, we investigate an outstandingly warm event in the year 986 AD or 991 AD, which has not been analyzed before.
Nicolas Stoll, Maria Hörhold, Tobias Erhardt, Jan Eichler, Camilla Jensen, and Ilka Weikusat
The Cryosphere, 16, 667–688, https://doi.org/10.5194/tc-16-667-2022, https://doi.org/10.5194/tc-16-667-2022, 2022
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We mapped and analysed solid inclusion in the upper 1340 m of the EGRIP ice core with Raman spectroscopy and microstructure mapping, based on bulk dust content derived via continuous flow analysis. We observe a large variety in mineralogy throughout the core and samples. The main minerals are sulfates, especially gypsum, and terrestrial dust minerals, such as quartz, mica, and feldspar. A change in mineralogy occurs around 900 m depth indicating a climate-related imprint.
Steven Franke, Daniela Jansen, Tobias Binder, John D. Paden, Nils Dörr, Tamara A. Gerber, Heinrich Miller, Dorthe Dahl-Jensen, Veit Helm, Daniel Steinhage, Ilka Weikusat, Frank Wilhelms, and Olaf Eisen
Earth Syst. Sci. Data, 14, 763–779, https://doi.org/10.5194/essd-14-763-2022, https://doi.org/10.5194/essd-14-763-2022, 2022
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The Northeast Greenland Ice Stream (NEGIS) is the largest ice stream in Greenland. In order to better understand the past and future dynamics of the NEGIS, we present a high-resolution airborne radar data set (EGRIP-NOR-2018) for the onset region of the NEGIS. The survey area is centered at the location of the drill site of the East Greenland Ice-Core Project (EastGRIP), and radar profiles cover both shear margins and are aligned parallel to several flow lines.
Nicolas Stoll, Jan Eichler, Maria Hörhold, Tobias Erhardt, Camilla Jensen, and Ilka Weikusat
The Cryosphere, 15, 5717–5737, https://doi.org/10.5194/tc-15-5717-2021, https://doi.org/10.5194/tc-15-5717-2021, 2021
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We did a systematic analysis of the location of inclusions in the EGRIP ice core, the first ice core from an ice stream. We combine this with crystal orientation and grain size data, enabling the first overview about the microstructure of this unique ice core. Micro-inclusions show a strong spatial variability and patterns (clusters or horizontal layers); roughly one-third is located at grain boundaries. More holistic approaches are needed to understand deformation processes in the ice better.
Tamara Annina Gerber, Christine Schøtt Hvidberg, Sune Olander Rasmussen, Steven Franke, Giulia Sinnl, Aslak Grinsted, Daniela Jansen, and Dorthe Dahl-Jensen
The Cryosphere, 15, 3655–3679, https://doi.org/10.5194/tc-15-3655-2021, https://doi.org/10.5194/tc-15-3655-2021, 2021
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We simulate the ice flow in the onset region of the Northeast Greenland Ice Stream to determine the source area and past accumulation rates of ice found in the EastGRIP ice core. This information is required to correct for bias in ice-core records introduced by the upstream flow effects. Our results reveal that the increasing accumulation rate with increasing upstream distance is predominantly responsible for the constant annual layer thicknesses observed in the upper 900 m of the ice core.
Sebastian Hellmann, Melchior Grab, Johanna Kerch, Henning Löwe, Andreas Bauder, Ilka Weikusat, and Hansruedi Maurer
The Cryosphere, 15, 3507–3521, https://doi.org/10.5194/tc-15-3507-2021, https://doi.org/10.5194/tc-15-3507-2021, 2021
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In this study, we analyse whether ultrasonic measurements on ice core samples could be employed to derive information about the particular ice crystal orientation in these samples. We discuss if such ultrasonic scans of ice core samples could provide similarly detailed results as the established methods, which usually destroy the ice samples. Our geophysical approach is minimally invasive and could support the existing methods with additional and (semi-)continuous data points along the ice core.
Paul D. Bons, Tamara de Riese, Steven Franke, Maria-Gema Llorens, Till Sachau, Nicolas Stoll, Ilka Weikusat, Julien Westhoff, and Yu Zhang
The Cryosphere, 15, 2251–2254, https://doi.org/10.5194/tc-15-2251-2021, https://doi.org/10.5194/tc-15-2251-2021, 2021
Short summary
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The modelling of Smith-Johnson et al. (The Cryosphere, 14, 841–854, 2020) suggests that a very large heat flux of more than 10 times the usual geothermal heat flux is required to have initiated or to control the huge Northeast Greenland Ice Stream. Our comparison with known hotspots, such as Iceland and Yellowstone, shows that such an exceptional heat flux would be unique in the world and is incompatible with known geological processes that can raise the heat flux.
Sebastian Hellmann, Johanna Kerch, Ilka Weikusat, Andreas Bauder, Melchior Grab, Guillaume Jouvet, Margit Schwikowski, and Hansruedi Maurer
The Cryosphere, 15, 677–694, https://doi.org/10.5194/tc-15-677-2021, https://doi.org/10.5194/tc-15-677-2021, 2021
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We analyse the orientation of ice crystals in an Alpine glacier and compare this orientation with the ice flow direction. We found that the crystals orient in the direction of the largest stress which is in the flow direction in the upper parts of the glacier and in the vertical direction for deeper zones of the glacier. The grains cluster around this maximum stress direction, in particular four-point maxima, most likely as a result of recrystallisation under relatively warm conditions.
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Short summary
What causes folds in ice layers from the km scale down to the scale visible in the drill core: buckle folding due to variations in viscosity between layers, or the effect of mechanical anisotropy of ice due to an alignment of the crystal-lattice planes? Power spectra of folds in ice, a biotite schist, and numerical simulations show that folding in ice is due to the anisotropy, as the folds are self-similar, meaning that there is no characteristic fold scale that would result from buckle folding.
What causes folds in ice layers from the km scale down to the scale visible in the drill core:...
