1 10 7 https://theses.otagogeology.org.nz/files/original/c7570259e401f1aaaa72bad3c2556341.pdf 732e1fda88d764b4aa9dc9d0804fb079 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 Giacalone Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student White, James D.L. Scott, James M. Abstract The Abstract for this thesis Swinburn Volcanic Complex is the remnant of a Miocene volcano, forming part of the Dunedin Volcanic Group (~ 24 - 9Ma), on the South Island of New Zealand. It is part of the Waipiata Volcanic Field, and its basalts are distinct from most others in that field. New analyses of Swinburn rocks, which have only very few mantle nodules, are compared with other new data from peridotite-bearing basanites collected from different volcanic rocks of Dunedin Volcanic Group. Swinburn basaltic rocks are geochemically and isotopically different than any other rock so far described from the intraplate Waipiata Volcanic Field or the Dunedin Volcanic Complex. I have identified geochemical and isotopic affinities (e.g. high 207Pb/204Pb trend together with lower trace element concentrations) of Swinburn rocks with those formed from Cretaceous basaltic magmas elsewhere in Zealandia and the Hikurangi Plateau. Percolation processes have: a) metasomatized the lithosphere, leaving strong geochemical imprints (e.g. carbonatite, OIB and HIMU-like), b) locally modified the thermal gradient c) produced metasomatic cumulates (amphibole-bearing veins and/or pyroxenites) which have major and trace-element compositions suitable for the mantle source that fed the Dunedin Volcanic Group. Within the footprint of this Group, Swinburn Volcanic Complex is an anomaly. Under the Swinburn Complex, percolating fluids interacted with one part of the lithospheric mantle that had been already metasomatized by Cretaceous melts. The combination of Cretaceous and Miocene percolation through the same mantle domain formed the distinctive geochemistry of Miocene Swinburn magmas. Petrographic and geochemical differences among samples from Swinburn also reveal that more than one batch of magma was involved in the formation of the complex. By combining field evidence with new geochemical data, two effusive eruptions or eruptive periods are inferred, separated an episode of magma intrusion. Reversed polarity of the magnetic field at the time of Swinburn effusion and intrusion activity was identified by paleomagnetic analysis. A magnetometer survey suggests the presence of several buried features. There are pegmatitic domains in the Swinburn basaltic rocks. Compaction of a crystal mush, together with the buoyant separation of residual melt rich in dissolved volatiles, is interpreted as the main mechanism driving the upward movement of Swinburn segregation domains and the formation of those segregation veins and domains. Results of this multidisciplinary analysis of the Swinburn Volcanic Complex, based on petrographic, mineralogical, geochemical and geophysical investigations are summarised below. 1) Older pyroclastic rocks, and the majority of the exposed vesicular lavas, represent the first activity of the complex, whereas younger pyroclastic products and a lava exposed in the western part of the complex (G7) formed during the last event. 2) The Swinburn body was emplaced during two effusive events by the intrusion of two batches of magma with similar composition. The higher amount of magnetic minerals forming the rocks of the Main body explains the inhomogeneous magnetic signal showed by my newly produced 3D magnetic map of the area. The association of magnetic profiles with cross sections unveiled several buried features such as a fault, possible thickness variations in the body, and places where Quarry and Main rocks overlap. 3) Compaction together with the buoyant rise of volatile-rich residual melt are interpreted to have been the main mechanisms driving upward movement of segregated residual liquids to form pegmatitic domains and veins. Compaction of the lower and central parts of the emplaced magma body caused dilatation and tearing in the upper crystallising front, which were filled by residual liquid to form segregation veins. 4) The concentration of major and trace elements is similar for plagioclases and clinopyroxenes crystallised near the top and bottom of the body but different for mineral crystallised near the mid-level of it. These differences reflect slower cooling of the interior of the body, furthest from basal and top cooling surfaces. The comparison of Swinburn features with those of volcanoes elsewhere worldwide sheds light on processes that regulate the origin of melts, and formation of segregation products during cooling of emplaced magmas. Following the main aim to determine the volcanic evolution and processes of the Swinburn Volcanic Complex and how it impacts on the wider volcanological perspective, this study demonstrates that even inside a broadly monogenetic volcanic field, individual volcanic complexes may be products of multiple eruptions. They can preserve significant local heterogeneities and magma source regions distinct from those of most volcanoes in the field. OURArchive handle The handle from the Otago University Research Archive (OURArchive) https://ourarchive.otago.ac.nz/handle/10523/8768 OURArchvive access level Open Access Department The department where the student is studying primarily. Geology Thesis description Number of pages, maps, CDs, etc. 245 Pages A4 Named locality Named locality describing the field area location. Swinburn 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 Swinburn Volcanic Complex, Central Otago, New Zealand Creator An entity primarily responsible for making the resource Giacalone, Emanuele Date A point or period of time associated with an event in the lifecycle of the resource 2018 Identifier An unambiguous reference to the resource within a given context 2018Giacalone biotite geochemistry geophysics greenschist magmatism Miocene Otago Schist Swinburn Volcano Waipiata Zealandia https://theses.otagogeology.org.nz/files/original/24bab10fbed5c5ad08b7217ba43042d8.pdf 5157f0cb7ecf8172be4a9f18aba8a874 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 (((171.303052248729 -44.9961429029632,171.711890051056 -45.2063152292055,171.619362892389 -45.2985952492034,171.229720706335 -45.0664819568099,171.303052248729 -44.9961429029632))) Author last name Last name of the Author Abbey Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Gorman, A.R. Abstract The Abstract for this thesis Submarine canyons are well documented, both around New Zealand and globally, but questions remain around the processes involved in their formation and evolution as well as around how their morphology reflects their developmental history. The Waitaki Canyon, located at the edge of the passive Otago Shelf in the Canterbury Basin, southeast New Zealand, presents an opportunity to investigate the near-surface features associated with a shelf-indenting submarine canyon using high-resolution seismic data. One such high-resolution survey was conducted in early 2015, collecting approximately 270 km of boomer seismic data in a high-density survey pattern centred at the head of the Waitaki Canyon. Approximately 40 km2 of the seafloor bathymetric data was also collected during that cruise. These data were analysed, along with approximately 100 km of boomer seismic data from a previous survey in the area and a selection of lower resolution seismic data from surveys conducted by the hydrocarbon industry, to investigate the subsurface structures in the vicinity of the Waitaki Canyon for evidence of changes in the canyon’s morphology throughout the Quaternary Period. South of the Waitaki Canyon, a large (several kilometres across) asymmetrical system of infilled paleochannels is intersected by a canyon-parallel survey line and canyon-perpendicular lines. Several high-order sequence boundaries are identifed throughout the survey area, and a region of seafloor depressions is observed on a ridge near the head of the canyon. Seismic reflections from the outer parts of the across-shelf survey lines are generally conformable, and do not show evidence of significant lateral migration of the canyon’s point of incision. The preferred interpretation of the stratigraphy and structures imaged in the data is that they represent the poorly preserved upper reaches of a series of paleochannels that had their heads somewhere west of the present canyon head and curved, or kinked, in very shallow S-shapes to rejoin the present path of the canyon. The canyon-parallel survey line thus intersects this kink and then approximately follows the centreline of the infilled channel, resulting in an asymmetric subsurface feature. The more recent symmetrical features are interpreted as non-axial tributaries or vestigial remains of this larger paleochannel. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/7400">http://hdl.handle.net/10523/7400</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. Waitaki Canyon Thesis description Number of pages, maps, CDs, etc. 142 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 2017Abbey Creator An entity primarily responsible for making the resource Abbey, Cameron James (Cam) 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 The Waitaki Canyon - An investigation of the Late Quaternary development of a shelf-indenting submarine canyon using high-resolution boomer seismic data Subject The topic of the resource Geophysics Canterbury Basin canyon geophysics Otago shelf Quaternary submarine canyon Waitaki https://theses.otagogeology.org.nz/files/original/3e7e9d4d4618847e75546af375722f37.pdf 886eb1e5f0b4c0cc5a5fbbe562692a68 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 (((169.803081781456 -44.1599965354529,169.89584575211 -44.1577932769353,169.912344443123 -44.247327558642,169.982143852039 -44.2820659801661,169.934064587607 -44.3393808826585,169.799308174647 -44.2785136990548,169.803081781456 -44.1599965354529))) Author last name Last name of the Author Krause Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Gorman, A.R. Abstract The Abstract for this thesis In a New Zealand first, a multi-channel hydrophone streamer has been used in conjunction with a boomer source to seismically image post-glacial sediments in the floor of Lake Ohau, Mackenzie Basin, adjacent to the Southern Alps, New Zealand. By integrating this dataset with existing geophysical data in a three-dimensional framework, a seismic stratigraphy has been defined, which, when combined with geological data will help develop a better understanding of climate variability in New Zealand since the retreat of glacier from the Ohau valley at the end of the last ice age. Lake Ohau exhibits sedimentary units typical of deglaciation and subsequent post-glacial deposition. The seismic stratigraphic units correspond to changing depositional environments; ice-contact and sub-glacial outwash and till; pro-glacial glacio-lacustrine meltwater deposits; post-glacial lacustrine deposits, are defined from the six seismic facies identified. Further- more, Lake Ohau exhibits multiple deformation structures, in particular, a landslide caused by catastrophic slope failure soon after the Ohau glacier had receded. Further structures present are multiple gravity flows, originating from the Ben Ohau range and slump deposits present along the eastern margin. Natural gas is a common and widespread feature within the Ohau stratigraphy and indicates the change from a pro-glacial to a post-glacial depositional regime. The results reveal that Lake Ohau has recorded the process of de-glaciation since the Last Glacial Maximum, with no active faulting, thus providing an excellent, undisturbed sedimentary record of the last ?18,000 years, when combined with well-hole control. This study allowed comparison of the different seismic surveys, demonstrating that CHIRP and multi-channel seismic data, respectively, provide quality images of high resolution and good depth penetration. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/7029">http://hdl.handle.net/10523/7029</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. Lake Ohau Canterbury Thesis description Number of pages, maps, CDs, etc. xvi, 147 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 2016Krause Creator An entity primarily responsible for making the resource Krause, Michael Anthony (Mike) 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 Characterising change in post-glacial climate using seismic imaging of Lake Ohau sediments Subject The topic of the resource Geophysics Paleoclimatology geophysics Lake Ohau paleoclimate Seismic seismic stratigraphy https://theses.otagogeology.org.nz/files/original/7672ce430b39c6b99de82ae112a7a4f8.pdf ac5f73578c5ff7f9e3d88828a86d14c7 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 ((170.2406113602338 -45.752754865914653,170.286167593748729 -45.753370537614913,170.285230837798963 -45.786689425434872,170.239670984917382 -45.785597026416852,170.2406113602338 -45.752754865914653)) Author last name Last name of the Author Bowie Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PGDipSci Advisers Who supervised/advised this student Gorman, A.R. Lee, D.E. Abstract The Abstract for this thesis In 2007, airborne geophysical surveys identified four sub-circular features presenting high magnetic intensity near Hindon, 25 km NW of Dunedin, within the Miocene Waipiata Volcanic Field (WVF). Similar magnetic anomalies within the WVF are associated with maar-diatreme structures, e.g., Foulden Maar or Gladsmuir diatreme. Subsequent excavations produced evidence that at least two of the basins contain extremely fossiliferous laminated diatomite and/or carbonaceous mudstone, deposited in former maar-lakes. Surface exposure is very limited, which means that geophysical surveys (ground-based magnetic, microgravity and seismic) are essential for accurately representing the size, depth and sediment infill. The large magnetic susceptibility of the basaltic diatreme allows for ground-based magnetic surveys to accurately characterise the size and extent of all four structures. It was found that these structures extend over an area of 16 km2 and are individual anomalies probably related to the same magma source. The relative density of rock within the maar complex then allowed for microgravity surveys to be conducted. Schist typically has a density of 2.73, basalt 2.77, volcanic breccia 2.19 and diatomite 1.53 g/cm3. The relatively low density of diatomite in the subsurface produces a negative anomaly that has been characterised by a Worden Gravimeter survey. Two maars have yielded negative anomalies related to a thickness of diatomite in the subsurface. The final geophysical method was a seismic survey conducted in Maar One. The seismic plot has revealed the thickness and lithologies of the sediment infill within Maar One. This has clarified that at least one of these deposits is a suitable candidate for full coring and paleoenvironmental studies, as at Foulden Maar some 25 km to the northwest. An integrated geophysical interpretation of Maar One has indicated that 160 to 190 m of laminated sediment is present within Maar One. Seismic and microgravity surveys have allowed for selection of an appropriate location to recover this maximum thickness. These two methods provide a generally consistent interpretation of basin thickness (although the thickest locations lie 150 m apart in the two models. A site between these points is most suitable for a drill core to be located. The Foulden core yielded 127 m of diatomite, enabling the reconstruction of a 100,000- year-long terrestrial record of climate, fossil biodiversity and ecosystems. A potential 190 m core of diatomite at Hindon suggests this record could be extended and improved. New samples of volcanic rock have been selected for radiometric dating to confirm the early Miocene age established by preliminary palynological biostratigraphy. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Hindon Maar Hindon East Otago Thesis description Number of pages, maps, CDs, etc. xvi,149 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 2015Bowie Creator An entity primarily responsible for making the resource Bowie, Elliot Date A point or period of time associated with an event in the lifecycle of the resource 2015 Title A name given to the resource Geophysical Characterisation of the Hindon Maar Complex Subject The topic of the resource Geophysics geophysics Hindon Maar maar https://theses.otagogeology.org.nz/files/original/50a4e0dcbcb448d739a5885be5fffe2d.pdf a01e79eeebff68593b9b672813d98afc 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 ((168.129798292555108 -46.866871216132274,168.820674424231555 -47.046643615102241,167.316313010076215 -47.462810187680944,166.457614591019961 -47.27869004424592,166.586064309207472 -47.143061179637222,167.535415726265455 -47.28057919503506,168.170908449822406 -47.10438777292449,168.255900278215876 -47.050791999815083,168.214104112528958 -46.972840710925077,167.985700127705314 -46.922555499295029,167.98099675628842 -46.898533089273009,168.125922291052632 -46.909573671999979,168.129798292555108 -46.866871216132274)) Author last name Last name of the Author Lennon Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Gorman, A.R. Abstract The Abstract for this thesis The sedimentary basins that have developed to the east and west of Stewart Island are linked through similar tectonic and depositional processes during their formation. The sediment supply and tectonic rifting phases are common to both basins, while sedimentation rates and tectonic subsidence define their unique characteristics. To the east, the Great South Basin is the Campbell Plateau's largest sedimentary basin; it has accumulated up to 8.6 km of sediment since it was formed during mid-Cretaceous rifting related to the separation of New Zealand from western Antarctica. West of Stewart Island lies the Solander Basin, which formed during the Cretaceous - late Eocene extensional regime that led to the opening of the Tasman Sea. Hydrocarbon exploration using seismic and well data has suggested that some of the rift basins formed by the spreading of the Tasman Sea and the break-up of Gondwana have become significant petroleum basin depocentres. In this thesis, high-resolution seismic data have been used in conjunction with existing data to further investigate the geological history and hydrocarbon potential of these basins. Several specific features are addressed as outlined below. On the southeastern side of Stewart Island, a detachment fault associated with late Cretaceous rifting from Gondwana has previously been proposed for the region. Information on the offshore geometry and extent of this, the Sisters Shear Zone, is limited - particularly with regard to its morphology and geological history. Recent work has allowed the dating of rifting episodes across the zone, but its general form is still mostly unknown. This study investigates the shear zone using high-resolution seismic imaging to reconstruct seafloor morphology and shallow fault geometry. High frequency, sub-bottom images were acquired aboard the University of Otago's R/V Polaris II, while seismic processing and interpretation techniques have been employed to investigate the shallow geometry and location of the offshore segment of this proposed detachment fault. On the west side of Stewart Island, a 240-km-long line of multi-channel seismic reflection data, recorded aboard R/V Maurice Ewing in 1996, has imaged several complex structural features along the shelf adjacent to the Solander Basin. Reprocessing of these data and further high-resolution imaging focuses on faulting that appears to outcrop on the seafloor, as well as inferred erosional features on the shelf margin. The collection of high-frequency boomer data in January 2009 has improved the resolution and interpretability of these features. Direct comparison of single-channel boomer data and multi-channel reflection data has revealed several near surface features which are below the Rayleigh resolution limit of the older low-frequency data, including a Bottom Simulating Reflection and turbidity/contour current erosional features. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/5058">http://hdl.handle.net/10523/5058</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. Stewart Island Thesis description Number of pages, maps, CDs, etc. xiv, 114 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 2014Lennon Creator An entity primarily responsible for making the resource Lennon, Tim 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 Linking Shallow and Deep Features on the Shelf East and West of Stewart Island Subject The topic of the resource Geophysics Boomer gas gas hydrate geophysics Great South Basin Hydrate New Zealand oil Seismic seismic stratigraphy sequence stratigraphy shelf margin Solander Basin Stewart Island https://theses.otagogeology.org.nz/files/original/9412452d7853be3c9b7f7db9d5ecea16.pdf 849601d711c08df160664c194fdb1528 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 ((170.49208587144679 -45.875505277967079,170.708448802772551 -45.754309756642918,170.757785817279682 -45.77958032861909,170.555098806497938 -45.900209980862101,170.49208587144679 -45.875505277967079)) Author last name Last name of the Author Shears Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Smith, A. Gorman, A.R. Abstract The Abstract for this thesis Urban tidal inlets often lend themselves to economically important port development. In many cases, such inlets are artificially deepened and maintained for continuous human use. A range of ecological, hydrological, sedimentological and financial impacts can result from such manipulation. A good understanding of a sedimentary system provided by a comprehensive sediment budget allows informed decisions and planning and encourages sustainable coastal management. The aim of this research was to develop, for the first time, a sediment budget for Otago Harbour, on the southeast coast of New Zealand. Otago Harbour is a highly modified tidal inlet that occupies two river-incised (and/or fault-incised) volcanic valleys. Previous research has investigated many sediment inputs and outputs for Otago Harbour but there is a lack of research relating to sediment storage, thickness and sedimentation rate. This thesis assesses sediment thickness throughout Otago Harbour using three complementary methods: (1) a geometric bedrock model, (2) land-based gravity anomaly profiling, and (3) marine seismic reflection surveying. The geometric model, developed from topography and bore records using a maximum bedrock depth of 120 m (sea level at the last glacial maximum), estimated a maximum sediment volume in Otago Harbour of almost 5 billion m3 . Land gravity surveys (at Aramoana, Upper Harbour Basin and St Kilda/St Clair) and marine seismic reflection surveys refined this estimate to 1.62 billion m3 . Gravity modelling found the maximum sediment thickness to be -100 m at the modem harbour entrance and > 70 m at the St Kilda paleo-river mouth, whereas the seismic survey found the greatest basement depth ( -76 m) just inside the entrance at Harington Point. Taken together, these findings suggest that the sediment package accumulated at a rate of -90,000 m3/y since the last glacial maximum (equivalent to -2 mm/y). However, this rate of storage no longer occurs because of the current dredging regime. In the present sediment budget, sediment entering the harbour on the flood tide (619,000 m3/y) is the dominant sediment input to the system (626,000 m3/y), though most of it exits the harbour on the ebb tide (516,000 m3/y). The difference is more than compensated for by seafloor dredging, which removes more sediment than the net 111 amount entering the harbour (-28,000 m3/y), thus removing stored sediment. As a result, the harbour's sedimentary system is in deficit, and the deficit is likely to increase in the future if dredging continues at the same long-term rate (244,000 m3/y). Otago Harbour can no longer be deemed an "infilling harbour"; human intervention has overturned that natural balance. Instead, the system's deficit may explain recent erosion at Te Rauone Beach. Furthermore, the lack of carbonate sediment accumulation, due also to changes in early seafloor processes, means that Otago Harbour plays a reduced role in preservation of carbonate information and sequestering of atmospheric C02. Human activities in other urban tidal inlets may have caused similar deficits. As modelled for Otago Harbour, the next century promises to bring a great deal of change (climate, ocean chemistry, urban development) with unexpected consequences for urban tidal inlets. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Otago Harbour Thesis description Number of pages, maps, CDs, etc. xvi. 170 p. ill (some col) maps folded in pocket. 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 2010Shears Creator An entity primarily responsible for making the resource Shears, Amy Date A point or period of time associated with an event in the lifecycle of the resource 2010 Title A name given to the resource Characterisation of the sediment budget of Otago Harbour: a geophysical and sedimentological study Subject The topic of the resource Geophysics sedimentology geophysics modified tidal inlet sediment budget sedimentology. https://theses.otagogeology.org.nz/files/original/203daaad11c692ef4ff01ba6bd47f6a1.pdf d421ad951a92085726593646cf2d162f 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 Wilson Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Koons, P. Landis, C.A. Abstract The Abstract for this thesis A series of high resolution single channel seismic (SCS) lines from the Canterbury Bight are presented, that extend from the Rangitata River mouth to beyond the shelf break, penetrate up to 150m, and sample 7 (possibly 8) sea-level cycles. Sediments on the outer shelf comprise a series of prograding foresets deposited during periods of late sea-level regression and lowstand. When the sea-level was lowest the river appears to have deposited lobate sands onto the most recent foreset, building out a shore-face barrier. Rapid sea-level rise submerges and preserves these features. Periods of stillstand are observed as either elongate, locally prograding sands that overlie the transgressive erosion surface, or wave cut erosion features. During periods of sea-level highstand marine and fluvial sediments interfinger in a complex manner. Deposition in the Canterbury Bight, during the Late Quaternary, appears to be bimodal; during sea-level regression and lowstand, sediments are actively deposited within 20km of the present-day coastline and at the paleo-shelf edge. A gap of non-deposition developed and widened with sea-level fall - this encouraged the development of the regressive sequence boundary. During sea-level transgression, this gap narrowed and a marine ravinement surface developed that reoccupied and may have eroded the resgressive sequence boundary. During periods of sea-level highstand, deposition occurs at the coast where wave-action and longshore currents redistribute the sediment. I use the term Depositional Shoreline Break Point (DSBP) to represent the position where sea-level reached its minimum. DSBP features are recognised on all seismic dip-lines, and are used to determine the age of sediments and associated unconformities. A fuzzy-logic based numerical model is used to simulate sediment deposition in the Canterbury Bight during the most recent sea-level cycle. The results are consistent with the idea that the sediments are predominantly deposited during periods of relatively slow sea-level regression. I propose the transgressive surface as a seismically recognisable horizon that separates successive sediment sequences. Power spectra of topography and Bouguer gravity data from the central South Island exhibit the effects of deformation associated with oblique convergence between the Australian and Pacific plates. For cross-sections perpendicular to the length of the South Island, at wavelengths (λ > 60 ± 20km), topography correlates well with Bouguer Gravity suggesting that long wavelength topographic features are associated with, or may even cause, lithospheric density variations. Bouguer gravity anomalies in the Canterbury Basin are likely to be the result of shallow sediment density variations. Short wavelength (λ < 60km) periodic loads (topography) are only partially compensated by a relatively rigid (Tᵉ > 5km) lithosphere. Bouguer gravity observations suggest that the central South Island topography is compensated (and in places over-compensated) at depth, implying that either the elastic plate rigidity has been overestimated, or other mechanisms for isostatic compensation are occurring. A 2D numerical model allows for the consideration of distributed loads and restoring forces, thereby applying more realistic input parameters. The model that best fits seismic and gravity contraints corresponds to a broken elastic plate (Tᵉ = 30-40km) loaded with topography and a subsurface load (equivalent to between 50 and 80km subducted cold mantle-lithosphere). The accommodation of sediments in the Canterbury Basin is discussed in terms of subsidence, compaction, bathymetric effects, and elastic flexure. Modelling of thermal subsidence indicates that ≈ 93% of the total thermal subsidence occurred by the middle Oligocene (30Ma), with only ≈ 193m since then. For regions where the dominant mode of sediment deposition is progradation, petroleum well data are likely to overestimate subsidence rates. The load of the Neogene sediment body resulted in ≈395m compaction of sediments at the Clipper 1 petroleum well (4507 total compacted thickness). Elastic flexure of the Canterbury Basin, by emplacement of the Neogene sediment load, is determined considering two conceptual models; the first considers a single load, the second, a stacked sequence of prograding clinoforms. The flexural model that best fits gravity and seismic control corresponds with a broken plate (Tᵉ = 30km) loaded with topography, subsurface load (equivalent to 50km subducted cold mantle-lithosphere) and the Neogene sediment package. The present-day Moho relief is determined assuming that, by the early Miocene (20Ma), the central South Island and Canterbury Basin lithosphere had reached a state of isostatic equilibrium, and that the Moho relief would reflect bathymetry at that time. Present-day Moho relief is the combination of paleo-Moho relief and best-fit elastic flexure. The results indicate a ≈ 3.4° westward dipping Moho. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/5850">http://hdl.handle.net/10523/5850</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. Canterbury Basin Thesis description Number of pages, maps, CDs, etc. 157 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 1998Wilson Creator An entity primarily responsible for making the resource Wilson, David, 1967- Date A point or period of time associated with an event in the lifecycle of the resource 1998 Title A name given to the resource Canterbury basin : a geophysical and stratigraphic investigation Subject The topic of the resource geophysics geophysics stratigraphy