The Relevance of Grain Dissection for Grain Size Reduction in Polar Ice: Insights from Numerical Models and Ice Core Microstructure Analysis
The flow of ice depends on the properties of the aggregate of individual ice crystals, such as grain size or lattice orientation distributions. Therefore, an understanding of the processes controlling ice micro-dynamics is needed to ultimately develop a physically based macroscopic ice flow law. We...
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| Format: | Article |
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Frontiers Media S.A.
2017-09-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | http://journal.frontiersin.org/article/10.3389/feart.2017.00066/full |
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| author | Florian Steinbach Ernst-Jan N. Kuiper Ernst-Jan N. Kuiper Jan Eichler Jan Eichler Paul D. Bons Martyn R. Drury Albert Griera Gill M. Pennock Ilka Weikusat Ilka Weikusat |
| author_facet | Florian Steinbach Ernst-Jan N. Kuiper Ernst-Jan N. Kuiper Jan Eichler Jan Eichler Paul D. Bons Martyn R. Drury Albert Griera Gill M. Pennock Ilka Weikusat Ilka Weikusat |
| author_sort | Florian Steinbach |
| collection | DOAJ |
| description | The flow of ice depends on the properties of the aggregate of individual ice crystals, such as grain size or lattice orientation distributions. Therefore, an understanding of the processes controlling ice micro-dynamics is needed to ultimately develop a physically based macroscopic ice flow law. We investigated the relevance of the process of grain dissection as a grain-size-modifying process in natural ice. For that purpose, we performed numerical multi-process microstructure modeling and analyzed microstructure and crystallographic orientation maps from natural deep ice-core samples from the North Greenland Eemian Ice Drilling (NEEM) project. Full crystallographic orientations measured by electron backscatter diffraction (EBSD) have been used together with c-axis orientations using an optical technique (Fabric Analyser). Grain dissection is a feature of strain-induced grain boundary migration. During grain dissection, grain boundaries bulge into a neighboring grain in an area of high dislocation energy and merge with the opposite grain boundary. This splits the high dislocation-energy grain into two parts, effectively decreasing the local grain size. Currently, grain size reduction in ice is thought to be achieved by either the progressive transformation from dislocation walls into new high-angle grain boundaries, called subgrain rotation or polygonisation, or bulging nucleation that is assisted by subgrain rotation. Both our time-resolved numerical modeling and NEEM ice core samples show that grain dissection is a common mechanism during ice deformation and can provide an efficient process to reduce grain sizes and counter-act dynamic grain-growth in addition to polygonisation or bulging nucleation. Thus, our results show that solely strain-induced boundary migration, in absence of subgrain rotation, can reduce grain sizes in polar ice, in particular if strain energy gradients are high. We describe the microstructural characteristics that can be used to identify grain dissection in natural microstructures. |
| first_indexed | 2024-12-12T16:22:24Z |
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| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-12T16:22:24Z |
| publishDate | 2017-09-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-514d310f18f947498793c63888f969b32022-12-22T00:18:56ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632017-09-01510.3389/feart.2017.00066269828The Relevance of Grain Dissection for Grain Size Reduction in Polar Ice: Insights from Numerical Models and Ice Core Microstructure AnalysisFlorian Steinbach0Ernst-Jan N. Kuiper1Ernst-Jan N. Kuiper2Jan Eichler3Jan Eichler4Paul D. Bons5Martyn R. Drury6Albert Griera7Gill M. Pennock8Ilka Weikusat9Ilka Weikusat10Department of Geosciences, Eberhard Karls University Tübingen, Tübingen, GermanyAlfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, GermanyDepartment of Geosciences, Utrecht University, Utrecht, NetherlandsDepartment of Geosciences, Eberhard Karls University Tübingen, Tübingen, GermanyAlfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, GermanyDepartment of Geosciences, Eberhard Karls University Tübingen, Tübingen, GermanyDepartment of Geosciences, Utrecht University, Utrecht, NetherlandsDepartament de Geologia, Universitat Autònoma de Barcelona, Barcelona, SpainDepartment of Geosciences, Utrecht University, Utrecht, NetherlandsDepartment of Geosciences, Eberhard Karls University Tübingen, Tübingen, GermanyAlfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, GermanyThe flow of ice depends on the properties of the aggregate of individual ice crystals, such as grain size or lattice orientation distributions. Therefore, an understanding of the processes controlling ice micro-dynamics is needed to ultimately develop a physically based macroscopic ice flow law. We investigated the relevance of the process of grain dissection as a grain-size-modifying process in natural ice. For that purpose, we performed numerical multi-process microstructure modeling and analyzed microstructure and crystallographic orientation maps from natural deep ice-core samples from the North Greenland Eemian Ice Drilling (NEEM) project. Full crystallographic orientations measured by electron backscatter diffraction (EBSD) have been used together with c-axis orientations using an optical technique (Fabric Analyser). Grain dissection is a feature of strain-induced grain boundary migration. During grain dissection, grain boundaries bulge into a neighboring grain in an area of high dislocation energy and merge with the opposite grain boundary. This splits the high dislocation-energy grain into two parts, effectively decreasing the local grain size. Currently, grain size reduction in ice is thought to be achieved by either the progressive transformation from dislocation walls into new high-angle grain boundaries, called subgrain rotation or polygonisation, or bulging nucleation that is assisted by subgrain rotation. Both our time-resolved numerical modeling and NEEM ice core samples show that grain dissection is a common mechanism during ice deformation and can provide an efficient process to reduce grain sizes and counter-act dynamic grain-growth in addition to polygonisation or bulging nucleation. Thus, our results show that solely strain-induced boundary migration, in absence of subgrain rotation, can reduce grain sizes in polar ice, in particular if strain energy gradients are high. We describe the microstructural characteristics that can be used to identify grain dissection in natural microstructures.http://journal.frontiersin.org/article/10.3389/feart.2017.00066/fullice microstructure modelingcryo-ebsdfabric analyserice deformationdynamic recrystallizationgrain size evolution |
| spellingShingle | Florian Steinbach Ernst-Jan N. Kuiper Ernst-Jan N. Kuiper Jan Eichler Jan Eichler Paul D. Bons Martyn R. Drury Albert Griera Gill M. Pennock Ilka Weikusat Ilka Weikusat The Relevance of Grain Dissection for Grain Size Reduction in Polar Ice: Insights from Numerical Models and Ice Core Microstructure Analysis Frontiers in Earth Science ice microstructure modeling cryo-ebsd fabric analyser ice deformation dynamic recrystallization grain size evolution |
| title | The Relevance of Grain Dissection for Grain Size Reduction in Polar Ice: Insights from Numerical Models and Ice Core Microstructure Analysis |
| title_full | The Relevance of Grain Dissection for Grain Size Reduction in Polar Ice: Insights from Numerical Models and Ice Core Microstructure Analysis |
| title_fullStr | The Relevance of Grain Dissection for Grain Size Reduction in Polar Ice: Insights from Numerical Models and Ice Core Microstructure Analysis |
| title_full_unstemmed | The Relevance of Grain Dissection for Grain Size Reduction in Polar Ice: Insights from Numerical Models and Ice Core Microstructure Analysis |
| title_short | The Relevance of Grain Dissection for Grain Size Reduction in Polar Ice: Insights from Numerical Models and Ice Core Microstructure Analysis |
| title_sort | relevance of grain dissection for grain size reduction in polar ice insights from numerical models and ice core microstructure analysis |
| topic | ice microstructure modeling cryo-ebsd fabric analyser ice deformation dynamic recrystallization grain size evolution |
| url | http://journal.frontiersin.org/article/10.3389/feart.2017.00066/full |
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