1 10 3 https://theses.otagogeology.org.nz/files/original/e85e8c9fe7d80858c4e21de3fd56adba.pdf 128149cf1aa08f62c84c5b56eda712a6 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 Location WKT (WGS84) The location stored in WKT (WGS84) format MULTIPOLYGON (((174.516292314169 -80.7113702485974,170.914290973674 -80.6857239691589,170.772115898609 -79.9224712681925,174.638031600643 -79.9844705027868,174.516292314169 -80.7113702485974))) Author last name Last name of the Author van Haastrecht Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Gorman, A.R. Ohneiser, C. Abstract The Abstract for this thesis The Ross Ice Shelf (RIS) is the largest ice shelf in the world. It buttresses ice flow from both the East Antarctic Ice Sheet (EAIS) and the West Antarctic Ice Sheet (WAIS). Today the RIS does not appear to be retreating or advancing. Understanding what controls the ice shelf’s stability, and how it may respond to future warming and oceanic change is vital, as its collapse would accelerate global sea level rise. Understanding the rates at which physical processes occurred in the past during ice shelf and ice sheet retreat can improve our models for future climate change. This study aimed to answer two main research questions: first, to characterise seafloor bathymetry and substrates in the vicinity of a future hot water drill site and make informed decisions concerning seafloor coring/sampling locations, and second, to characterise the roughness of the ice shelf’s basal surface. Field work was conducted during the 2015/2016 Antarctic field season as opposed to the 2014/2015 season, after a one year delay due to logistical constraints. As a result, this study focussed on reprocessing previous data, survey design, and modelling, conducted prior to data collection in Antarctica. The preliminary work involved a comparative study between conventional spiked geophone data and snow streamer on data previously collected on the McMurdo Ice Shelf (MIS), and a detailed survey design for the November 2015 survey. Synthetic shot records were generated to test the effect of ice thickness variations. The snow streamer and weight drop seismic source data acquisition system were an effective method of data collection on the RIS. This combined system allowed for rapid data collection, and facilitated the collection of 45.8 km of multichannel seismic reflection data. The seismic data are interpreted to reveal two seismic facies, separated by an erosion surface, of at least 180 m thickness. The upper seismic facies is characterised by two cycles of high-amplitude, mostly continuous, horizontal strata, and the lower facies is characterised by irregular, discontinuous, dipping strata. The two seismic facies and erosion surface are interpreted to reflect the change in glaciation regime that occurred in the late Pliocene (approximately 3 Ma), where the lower sedimentary packages consists of sediments deposited under a warmer, wet-base regime and overlying sediments that were deposited by colder, dry-base glaciers. It is unlikely that deeper bedrock structures were imaged in this study. From the seismic data alone, it is recommended that any future hot water drill site locations are positioned close to the South Pole Overland Traverse (SPOT) road and the 2015 season base camp. The basal ice interface was not imaged distinctly in this study, likely due to the interference of surface waves and the presence of marine ice. It lies within as a seismically opaque zone in the upper 200 ms, after which the signal changes character to low- to moderate-amplitudes in the water column. It is hypothesised that this is due to either the presence of marine ice, surface waves obscuring the reflection, or a combination of the two. The RIS data also display a relatively strong intra-ice multiple (modelled in the synthetic shot records), and contain strong surface waves, which were a significant aspect of the shot records. Due to the nature of collecting data close to the end of this study, several processing and analysis options still need to be investigated for these data including, but not limited to, better analysis of the surface waves and of the intra-ice multiple characterise ice properties, and calculations of reflection and transmission co-efficient values derived from the intra-ice multiple and seafloor. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/7032">http://hdl.handle.net/10523/7032</a> OURArchvive access level Open Access Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Ross Ice Shelf Antarctica Thesis description Number of pages, maps, CDs, etc. 173 pages A4 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 2017van_Haastrecht Creator An entity primarily responsible for making the resource van Haastrecht, Laurine Nathalie (Laurine) Date A point or period of time associated with an event in the lifecycle of the resource 2017 Title A name given to the resource Vulnerability of the Ross Ice Shelf: Seismic Site Characterisation and Drilling Recommendation Subject The topic of the resource Geophysics Ross Ice Shelf seismic survey snow streamer https://theses.otagogeology.org.nz/files/original/d0a3a2042d28edca51a0aab8c3a8573d.pdf 92ff7f04e664b18fa767581e119e001b 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 Location WKT (WGS84) The location stored in WKT (WGS84) format MULTIPOLYGON (((170.564411096478 -45.5386272690959,170.559627119514 -45.5301419507655,170.559900945011 -45.5238127978249,170.568560274751 -45.5209967573922,170.573787365999 -45.5223463862715,170.579072506025 -45.5255070079308,170.579847091468 -45.5311439598299,170.571779808488 -45.5359263420047,170.564411096478 -45.5386272690959))) Author last name Last name of the Author Mawson Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Ohneiser, C. Abstract The Abstract for this thesis The Waipiata Volcanics comprise a monogenetic volcanic field in East Otago. A paleomagnetic study was conducted on Mt MacKenzie, a maar-diatreme volcano of this field, to determine the emplacement processes of a massive lapilli tuff and a basalt dike. Samples were collected from the basalt and closely spaced samples were collected in a transect through the tuff perpendicular to the dike. Paleomagnetic techniques used included anisotropy of magnetic susceptibility (AMS), thermal and alternating field demagnetisation, and hysteresis and isothermal remanent magrnetisation (IRM). AMS data indicate flow fabrics in the tuff orient steeply upwards out of the volcano; this is interpreted to have formed as a result of a debris jet up through the tuff. Thermal demagnetisation data reveal two magnetisation components, with an inflection point at 110-230°C. Alternating field (AF) demagnetisation data show the same components, with an inflection point at 3-20 mT. The two demagnetisation components are inferred to indicate that the intruding dike completely reset the magnetisation of the tuff and both were later overprinted by a viscous remanent magnetisation (VRM). Hysteresis data show saturation magnetisations of 8.89 × 10-2 Am2/kg to 2.60 × 10-1 Am2/kg, remanence magnetisations of 3.39 × 10-3 Am2/kg to 6.19 × 10-2 Am2/kg, and coercivities of 3.04 × 10-3 T to 1.91 × 10-2 T, consistent with mineralogy containing magnetite and maghemite. They display decreasing coercivity and concentration with distance from the dike, which could signify hydrothermal alteration processes while the dike was still hot. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. East Otago Thesis description Number of pages, maps, CDs, etc. 45 pages A4, A3 map in back pocket, Digital appendices 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 2016Mawson Creator An entity primarily responsible for making the resource Mawson, Jasmine 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 Paleomagnetism of the Waipiata Volcanics at Mt Mackenzie Subject The topic of the resource Paleomagnetics Volcanism AMS IRM VRM https://theses.otagogeology.org.nz/files/original/729bc8f856bc2972df381425d44f9bb3.pdf 487485504695e8b5f0115beac8325460 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 Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((166.091533061044828 -50.734988116718661,166.162539879670106 -50.722165330054374,166.174423866050915 -50.71990211904938,166.181257158219893 -50.733291185792147,166.109061940956565 -50.748184358540186,166.091533061044828 -50.734988116718661)) Author last name Last name of the Author Einvik-Heitmann Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PGDipSci Advisers Who supervised/advised this student Moy, C. Ohneiser, C. Abstract The Abstract for this thesis A sediment core (14PL001 – 39P4), collected from the Hanfield Inlet on the subantarctic Island of Auckland Island by a scientific research group from the University of Otago, have been subject to an environmental magnetic study by the use of u-channel samples. Lithostratigraphic analyses was carried out on the core, which contain the transition from a lacustrine environment to a marine environment through an inter-bedded sequence which was correlated to regional sea-level curves, indicating a date of ~8ka. High-resolution magnetic measurements of natural remanent magnetisation intensity, anhysteric remanent magnetisation intensity and magnetic susceptibility, and a stepwise alternating field demagnetisation were performed on the u-channels. Declination, inclination and median destructive field were determined throughout the core by the use of a principal component analysis of orthogonal component vectors. Chemical alteration of titanomagnetites and authigenic growth of pyrrhotite and greigite dominated a larger interval, complicating environmental interpretations. Magnetic mineralogy were therefore further investigated on sub samples by measuring thermomagnetic behaviour and isothermal remanent magnetisation together with energy dispersive spectroscopy. A proxy sensitive to magnetic grain size changes, related to the Holocene westerly wind variability was developed by plotting the measurements of the anhysteric remanent magnetisation intensity on the magnetic susceptibility measurements. The proxy together with sedimentary and mineralogical observations support the suggested pattern of a strong core in the westerly winds for the early Holocene, succeeded by a weak core for the late Holocene. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Hanfield Inlet Auckland Islands Thesis description Number of pages, maps, CDs, etc. 86 pages A4 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 2014Einvik-Heitmann Creator An entity primarily responsible for making the resource Einvik-Heitmann, Vegar Date A point or period of time associated with an event in the lifecycle of the resource 2014 Title A name given to the resource Unravelling the Secrets of the Subantarctic Auckland Island Inlets: An Environmental Magnetic Study of a Holocene Sediment Core Subject The topic of the resource Paleoclimatology 14PL001-39P4 Environmental magnetism Holocene paleomagnetism sediment core