Show simple item record

dc.contributor.advisorPrior, David John
dc.contributor.authorCraw, Lisa
dc.date.available2018-06-12T20:49:42Z
dc.date.copyright2018
dc.identifier.citationCraw, L. (2018). Causes and Consequences of Heterogeneous Flow Behaviour in Ice (Thesis, Master of Science). University of Otago. Retrieved from http://hdl.handle.net/10523/8092en
dc.identifier.urihttp://hdl.handle.net/10523/8092
dc.description.abstractMany ice flow models treat polar ice as chemically pure and mechanically isotropic, while in reality it can have pre-existing crystallographic preferred orientations, soluble impurities, and mechanical heterogeneities which affect its behaviour. As a result, our predictions of ice flow behaviour can be inaccurate. We performed fixed-rate uniaxial compression experiments on both natural Antarctic ice and laboratory-made ice containing natural soluble impurities, alongside samples of pure, initially isotropic ice for comparison. In addition, we performed shear experiments on pure laboratory ice, and developed an entirely novel method of analysing changing local shear directions across a plane of a sample. All deformed samples were analysed using cryo- Electron Backscatter Diffraction to produce robust microstructural data. The results show that all ice containing soluble impurities, regardless of microstructure, behaves more weakly than pure ice, with a flow law stress exponent of n≈4 rather than the commonly assumed value of n≈3. Additionally, in natural ice strain is accommodated heterogeneously, as some grains fully recrystallise within strains of <0.2, while others do not recrystallise and show little evidence of strain accumulation. This heterogeneity is only seen in natural ice, and is therefore assumed to be a result of its larger grain size or irregular impurity distribution. Kinematic analysis of sheared pure ice samples shows that local shear directions can vary significantly relative to the imposed shear direction, without microstructure being significantly affected. The analytic methods developed for kinematic analysis may be applied to other materials.
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectice deformation
dc.subjectice microstructure
dc.subjectstructural geology
dc.subjectglaciology
dc.titleCauses and Consequences of Heterogeneous Flow Behaviour in Ice
dc.typeThesis
dc.date.updated2018-06-12T04:41:59Z
dc.language.rfc3066en
thesis.degree.disciplineDepartment of Geology
thesis.degree.nameMaster of Science
thesis.degree.grantorUniversity of Otago
thesis.degree.levelMasters
otago.interloanyes
otago.openaccessAbstract Only
 Find in your library

Files in this item

FilesSizeFormatView

There are no files associated with this item.

This item is not available in full-text via OUR Archive.

If you would like to read this item, please apply for an inter-library loan from the University of Otago via your local library.

If you are the author of this item, please contact us if you wish to discuss making the full text publicly available.

This item appears in the following Collection(s)

Show simple item record