Deformation Microstructures : Antarctic Ice from EPICA Dronning Maud Land and Artificial Creep TestIce
The primary objective of this thesis is the investigation of microstructures obtained from samples from the EPICA Dronning Maud Land ice core from Antarctica. The goal is to gain understanding of deformation processes an deformation-related recrystallization mechanisms using these structures. The st...
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Universität Bremen
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ftsubbremen:oai:media.suub.uni-bremen.de:Publications/elib/2441 2023-05-15T13:42:31+02:00 Deformation Microstructures : Antarctic Ice from EPICA Dronning Maud Land and Artificial Creep TestIce Deformationsmikrostrukturen im Eis Hamann, Ilka Miller, Heinrich Spiegel, Cornelia 2007-12-20 application/pdf https://media.suub.uni-bremen.de/handle/elib/2441 https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000108890 eng eng Universität Bremen FB5 Geowissenschaften https://media.suub.uni-bremen.de/handle/elib/2441 urn:nbn:de:gbv:46-diss000108890 info:eu-repo/semantics/openAccess ice microstructures subgrain boundaries recrystallization flow deformation 550 550 Earth sciences and geology ddc:550 Dissertation doctoralThesis 2007 ftsubbremen 2022-11-09T07:09:49Z The primary objective of this thesis is the investigation of microstructures obtained from samples from the EPICA Dronning Maud Land ice core from Antarctica. The goal is to gain understanding of deformation processes an deformation-related recrystallization mechanisms using these structures. The structures are visualized with the new microstructure mapping method using the preferred sublimation along defect regions in the crystal. This method enables observation in high resolution as well as overview over a significant sample volume. In order to provide unambiguous proof of their deformational origin and to offer interpretation and characterization, experimental reproduction of the microstructural features are performed using creep tests.Subgrain boundaries and grain-boundary morphology are identified as the most direct effects of deformation and recrystallization processes, which are still easily observable. They can be used additionally to the conventional parameters (grain size, crystal-orientation distribution) to determine these mechanisms. Different sbugrain-boundary types observed in experimentally deformed samples as well as in natural ice indicate several formation processes.Results obtained from this new and novel data suggest a profound reconsideration of the classical tripartition of recrystallization regimes described in the literature in ice sheets. Instead, dynamic recrystallization in two of its forms (rotation recrystallization and strain-induced migration recrystallization) dominates the microstructure evolution in all depth regions of the EDML ice core.Results of systematic microstructure analysis of creep-test samples demonstrate the correlation of grain-substructure evolution and strain hardening during primary creep. Subgrain boundaries and dislocation walls acting as obstacles for dislocation motion was identified thereby as a main process of strain hardening in ice.The comparison of results from experimentally and naturally deformed ice enables a specification of the well-known ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Antarctica Dronning Maud Land EPICA ice core Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) Antarctic Dronning Maud Land |
institution |
Open Polar |
collection |
Media SuUB Bremen (Staats- und Universitätsbibliothek Bremen) |
op_collection_id |
ftsubbremen |
language |
English |
topic |
ice microstructures subgrain boundaries recrystallization flow deformation 550 550 Earth sciences and geology ddc:550 |
spellingShingle |
ice microstructures subgrain boundaries recrystallization flow deformation 550 550 Earth sciences and geology ddc:550 Hamann, Ilka Deformation Microstructures : Antarctic Ice from EPICA Dronning Maud Land and Artificial Creep TestIce |
topic_facet |
ice microstructures subgrain boundaries recrystallization flow deformation 550 550 Earth sciences and geology ddc:550 |
description |
The primary objective of this thesis is the investigation of microstructures obtained from samples from the EPICA Dronning Maud Land ice core from Antarctica. The goal is to gain understanding of deformation processes an deformation-related recrystallization mechanisms using these structures. The structures are visualized with the new microstructure mapping method using the preferred sublimation along defect regions in the crystal. This method enables observation in high resolution as well as overview over a significant sample volume. In order to provide unambiguous proof of their deformational origin and to offer interpretation and characterization, experimental reproduction of the microstructural features are performed using creep tests.Subgrain boundaries and grain-boundary morphology are identified as the most direct effects of deformation and recrystallization processes, which are still easily observable. They can be used additionally to the conventional parameters (grain size, crystal-orientation distribution) to determine these mechanisms. Different sbugrain-boundary types observed in experimentally deformed samples as well as in natural ice indicate several formation processes.Results obtained from this new and novel data suggest a profound reconsideration of the classical tripartition of recrystallization regimes described in the literature in ice sheets. Instead, dynamic recrystallization in two of its forms (rotation recrystallization and strain-induced migration recrystallization) dominates the microstructure evolution in all depth regions of the EDML ice core.Results of systematic microstructure analysis of creep-test samples demonstrate the correlation of grain-substructure evolution and strain hardening during primary creep. Subgrain boundaries and dislocation walls acting as obstacles for dislocation motion was identified thereby as a main process of strain hardening in ice.The comparison of results from experimentally and naturally deformed ice enables a specification of the well-known ... |
author2 |
Miller, Heinrich Spiegel, Cornelia |
format |
Doctoral or Postdoctoral Thesis |
author |
Hamann, Ilka |
author_facet |
Hamann, Ilka |
author_sort |
Hamann, Ilka |
title |
Deformation Microstructures : Antarctic Ice from EPICA Dronning Maud Land and Artificial Creep TestIce |
title_short |
Deformation Microstructures : Antarctic Ice from EPICA Dronning Maud Land and Artificial Creep TestIce |
title_full |
Deformation Microstructures : Antarctic Ice from EPICA Dronning Maud Land and Artificial Creep TestIce |
title_fullStr |
Deformation Microstructures : Antarctic Ice from EPICA Dronning Maud Land and Artificial Creep TestIce |
title_full_unstemmed |
Deformation Microstructures : Antarctic Ice from EPICA Dronning Maud Land and Artificial Creep TestIce |
title_sort |
deformation microstructures : antarctic ice from epica dronning maud land and artificial creep testice |
publisher |
Universität Bremen |
publishDate |
2007 |
url |
https://media.suub.uni-bremen.de/handle/elib/2441 https://nbn-resolving.org/urn:nbn:de:gbv:46-diss000108890 |
geographic |
Antarctic Dronning Maud Land |
geographic_facet |
Antarctic Dronning Maud Land |
genre |
Antarc* Antarctic Antarctica Dronning Maud Land EPICA ice core |
genre_facet |
Antarc* Antarctic Antarctica Dronning Maud Land EPICA ice core |
op_relation |
https://media.suub.uni-bremen.de/handle/elib/2441 urn:nbn:de:gbv:46-diss000108890 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766168716416909312 |