1 10 2 https://theses.otagogeology.org.nz/files/original/d071397f7b3d331ae29d9f0dfbbdfe3b.pdf e6fb9cebd434b0d2df9ed209c1e42584 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author Tooley Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Prior, D.J. Abstract The Abstract for this thesis Ice deformation experiments and related numerical modelling are necessary to increase our understanding of ice sheet flow, which is of extreme importance in predicting sea level rise in relation to global warming and climate change. We present the results of high temperature (?5?) uniaxial shortening experiments and finite element modelling of ice forced through a constriction. In our experiments we applied constant loads to columnar ice polycrystals oriented with their column axis normal to the shortening direction. We deformed samples to several increments of strain, between 0% and 14%. At these conditions the crystallographic preferred orientation (CPO) of columnar ice evolves from a large circle CPO to a CPO where two clusters exist at ~30° from the shortening direction. The rotation of grains via intracrystalline glide on basal planes is responsible for the CPO evolution at low strain (< 7.2% strain). At high strain, grain boundary migration recrystallisation is dominant, encouraging the growth of optimally aligned grains and the consumption of grains poorly aligned for basal slip. Our numerical model shows heterogeneous stress and strain rate fields developed in ice pushed through a constricting narrowing channel. A significant high stress (1MPa), high strain rate (1.0 x 10?7 s?1) and low velocity (2 x 10?9 s?1) zone develops along the ice-constriction interface. An optimised CPO would rapidly develop within this zone. A less significant high stress and high strain rate zone develops further into the ice interior where the velocity is faster and the ice is in extension. Ice is an ideal analogue for quartz because of its comparable basal-slip anisotropy. We present a novel columnar ice uniaxial shortening experiment that can be used to test the results of an existing numerical model for quartz dynamic recrystallisation. By deforming ice around a wooden dowel we simulated quartz deformation around a rigid porphyroclast. The CPO at 8% strain indicates that the deformation remains approximately two-dimensional, allowing for direct comparison with the 2D model outputs. This experiment should inspire more columnar experiments of this type and provide a means to further constrain quartz deformation conditions and mechanisms. Department The department where the student is studying primarily. Geology Thesis description Number of pages, maps, CDs, etc. 123 pages A4, digital appendix with 3D models Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2016Tooley Creator An entity primarily responsible for making the resource Tooley, Lauren Date A point or period of time associated with an event in the lifecycle of the resource 2016 Title A name given to the resource Creep in Columnar Ice: Insights from Laboratory Experiments and Simple Numerical Modelling Subject The topic of the resource Structural Geology experiments ice deformation strain https://theses.otagogeology.org.nz/files/original/3c079a4363d2febcd33901a461314b01.pdf a6bccff2151a9a4a08bbfd1bbe8912be Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author Henderson Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Koons, P. Abstract The Abstract for this thesis A number of techniques are reviewed with the intention of identifying the best method for deformation analysis. The method finally adopted for deformation analysis consists of two data reduction steps. Firstly, the geodetic observation data are used to adjust the survey station coordinates. In the second step the results of the first step in conjunction with a model for the deformation are used to estimate the motion within the region. Statistical testing is emphasised throughout the coordinate adjustment phase and the deformation modelling procedure. Estimates for strain and rotation rates are presented in a different fashion to those of previous studies; contours of the measurements are superimposed on their error .surfaces. This allows improved accuracy in reading the results of the analyses. Statistical testing shows that the deformation within Marlborough is statistically compatible with a constant station velocity model. This indicates that variations of station velocity over the time between the first and last surveys are insignificant. Inhomogeneous analysis (polynomial modelled velocity) is found to be superior to the method of forming many homogeneous strain rate estimates. Polynomial based deformation models appear to be a reasonable representation of motion within regions where survey stations are evenly spaced and where the discontinuous part (eo-seismic deformation) of the velocity surface is much smaller than the continuous part (inter-seismic deformation). In regions where survey stations are not evenly distributed or the complexity of the polynomial model is not easily adjusted to the amount of available information, then connected low-order polynomial surfaces appear to be a reasonable method of modelling the motion. The results of the analyses suggest a shear strain rate maximum over the Clarence and Awatere faults. Most of the Marlborough Fault Zone east of the Wairau Fault is experiencing shear strain rates of at least 3 x 10-7 I year. Generally the shear strain rate results are compatible with previous geodetic shear strain rate estimates within the region. Dilatational strain rate estimates are generally of low precision, however, significant variations of the dilatation rate surface are found. The geodetic results indicate that rotation rates are progressiyely more clockwise towards the west within the southern portion of the Marlborough Fault Zone. This trend is not carried on into Marlborough, where the relative rotation becomes progressively more clockwise towards the south. The orientation of the principal axis of horizontal s~ear strain over most of the study region is found to be statistically compatible with a model of shear strain release on the major faults. However, average inter-seismic shear strain rates, estimated from the slip-rates of major faults, are incompatible with the geodetic measurements. The geodetic measurements of dilatational strain rate are also found to be generally incompatible with the shape of the dilatational strain rate surface approximated from uplift rates. A different relationship ' between tectonic rotation rates and geodetic measurements from that described by Lamb (1987) is presented. Estimated relative tectonic rotation rates are found to be of very low precision and are not statistically significant. The total relative velocity over the Marlborough Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. South Island Thesis description Number of pages, maps, CDs, etc. 179 leaves : ill., maps ; 30 cm. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 1995Henderson Creator An entity primarily responsible for making the resource Henderson, Christopher Mark. Date A point or period of time associated with an event in the lifecycle of the resource 1995 Title A name given to the resource Geodetic analysis of horizontal crustal deformation within the northern South Island, New Zealand Subject The topic of the resource Geophysics crustal deformation geodetic South Island strain