1 10 9 https://theses.otagogeology.org.nz/files/original/57e00179957dc3c5a10d33062a463699.pdf 317e0a92009b8e549b0cc0d8040c2d00 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 (((169.007357194797 -44.4801048617569,168.852891876841 -44.7153959537916,168.644939480572 -44.8819889426719,168.53059861996 -44.8789917767537,168.652743501904 -44.4707082049925,169.007357194797 -44.4801048617569))) Author last name Last name of the Author Wellnitz Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Scott, J.M. Palin, J.M. Abstract The Abstract for this thesis In this thesis the chemistry and textures of void-filling hydrothermal carbonate and associated altered metamorphic and lamprophyric rock in western Otago, New Zealand, were studied. With this information a detailed model of the mobility behaviour of various elements is established. Conduits for CO2-bearing fluids were faults, joints, folds and, in the northernmost part of the study area, volcanic diatremes. The southernmost study area lies in the Shotover Valley, where many of the larger fault zones are auriferous. Throughout the studied area, many larger faults, including the gold-bearing ones, strike W to NW. In addition to these faults, there are also structures (i.e. veins and fold hinges) that trend northwards. The formation of most of the structures happened in the Oligocene -Miocene andwas closely connected to the movements along the newly forming Alpine Fault and reverse movements along the Moonlight Fault. Adjacent to the fluid conduits, the wall rock has been extensively altered. This alteration is especially obvious in greenschist and the altered rock has a pale creamy colour due to the replacement of various metamorphic phases (epidote, chlorite, actinolite) mostly by Fe-bearing carbonate and phyllosilicates. In quartzo-feldspathic greyschists the same metamorphic minerals as in greenschist are unstable in response to the incoming CO2-bearing fluid. However, as those minerals are less abundant in greyschist, the alteration is less obvious. Textural and chemical data of the individual metamorphic and hydrothermal minerals forming during replacement were obtained using SEM, microprobe and LA-ICP-MS. The hydrothermal minerals replacing metamorphic minerals describea diverse array of mineral textures, which give insight into relative solubility of the different mineral phases. The replacement reactions also attest to mobility and immobility of the different major and trace elements. For example, in the breakdown of epidote in rocks which contain metamorphic muscovite, Al is mobilised potentially in F-OH complexes and transported away from the original epidote site, whereafter carbonate forms. In cases where there is no muscovite in the rock, epidote is replaced by muscovite, hence resulting in local loss of Ca. At the same time, the REE of this epidote are also mobilised on microscopic scale (µm to mm) as the growing muscovite cannot accommodate the REE in its crystal structure. These REE are then incorporated in the ankerite replacing the chlorite. On a macroscopic scale (cm to m), Sr, Ba, Rb, K and Cs show the largest mobility during the hydrothermal alteration (sometimes up to 20 times enrichment in the altered rock compared to the unaltered rock) and are often brought into the rock by the hydrothermal fluid. The REE and Al, on the other hand, do not show any signs of mobility at thatscale. Overall, of all elements in alteration-sensitive metamorphic minerals, only titanium is shown to be immobile throughout, also on µm scale. In addition to carbonate forming in the hydrothermal alteration halo around fluid conduits, carbonate is also a common void-filling mineral, such as fractures and vesicles. The chemical composition of these carbonates shows that the different elements are controlled by various factors. Contents of Ca, Sr, Mg, Fe, Mn and according ratios show that these elements can travel metres to tens of metres in the fluid before they are precipitated in carbonate. REE contents and patterns in the carbonate are the product of the interplay between fluid- and rock-dominated processes; in cases were only little rock needs to be leached to form the carbonate, the REE patterns are very similar to the wall rock. In cases where relatively large rock volumes need to be leached to provide the main components of the void-filling carbonate, the REE content of the carbonate is dominated by fluid-controlled processes and the REE patterns reflect the relative solubility of the different REE in the fluid. Radiogenic isotopic compositions (Nd, Sr) of void filling carbonates and wall rock show that Nd and Sr in the carbonates travel different distances in the fluid conduit; Nd isotopic ratios show that the bulk of the LREE are transported for short distances in the fluid passing through the void (cm to dm), whereas Sr isotopic ratios confirm that Sr can be for transported many meters by the aqueous fluid. Stable isotope data (C, O) in conjunction with assessing the regional geological and tectonic settings permitted to reconstruct the history and sources of the fluids in the studied areas; after taking temperature effects on isotope fractionation and relative sample locations into account, it is concluded that two main fluid types were present in the studied area. One of these is a mixture of meteoric and magmatic components, while the other fluid interacted extensively with the metamorphic rock in Western Otago, but was most likely originally meteoric-derived water. Only in the volcanic diatremes is there indication that these two fluid types mix. Outside the diatreme, the isotopic composition of the carbonate give evidence that only the second mentioned fluid type was present, including in the auriferous structures and there is no indication that the gold-bearing and magmatic system had any connection to each other OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/7300">http://hdl.handle.net/10523/7300</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. Southern Alps Thesis description Number of pages, maps, CDs, etc. 257 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 2017Wellnitz Creator An entity primarily responsible for making the resource Wellnitz, Anne Katrin (Katrin) 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 Carbonate alteration associated with lamprophyres and orogenic gold, Southern Alps, New Zealand Subject The topic of the resource Igneous geology Metamorphic geology Alteration Carbonate Fluid gold Lamprophyres New Zealand radiogenic isotopes Rare Earth Elements stable isotopes https://theses.otagogeology.org.nz/files/original/1dc9fa6fea23b8854e51de7822a4883a.pdf 8c771bf043a96260d23b307a0fb56587 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 (((167.850350833773 -46.3762799337737,167.867105449267 -46.367889677738,167.889411266548 -46.3736546885395,167.890644223913 -46.3899051356639,167.882892749382 -46.3962262417941,167.856209525306 -46.3900721193642,167.850350833773 -46.3762799337737))) Author last name Last name of the Author Galloway Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Palin, J.M. Abstract The Abstract for this thesis Oraka Point is located along the Southland coast of New Zealand at an inferred intersection between the Median Batholith and Brook Street Terrane. Plutonic rock found at Oraka Point represents the western edge of the Eastern Province and is therefore pivotal in the understanding of processes and timing for accretion of the Brook Street Terrane to the Gondwana margin (Median Batholith). Geochemical analysis of major and trace elements of samples from Oraka Point yielded granite, quartz diorite, diorite and gabbro compositions. Samples of granitic and dioritic composition exhibit geochemical signatures consistent with a calc-alkaline magma series derived from the subcontinental lithosphere. Samples of gabbroic composition exhibit a minor affinity towards a tholeiitic magma series; again derived from the subcontinental lithosphere but with an asthenosphere influence. This, along with mobile element enrichment patterns, points to a setting in which Oraka Point was likely a part of a volcanic arc complex that was transitioning from an island arc setting to an active continental margin setting. Major and trace element data shows fractionation as the dominant factor in magma evolution at Oraka Point. Magnetite and plagioclase trace element compositions along with enclaves and clots found in situ, indicate magma mixing and mingling were also key processes. However, their role to date remains undefined in the formation of rock at Oraka Point. Fractionation trends show a geochemical affinity between the Hekeia Gabbro of Oraka Point and the Hekeia Gabbro of the Longwood Range. This affinity was made prior to this research through petrographic similarities and minor geochemical work. This affinity confirms Oraka Point as being a member of the Longwood Suite. LA-ICP-MS U-Pb zircon data of five samples obtained from Oraka Diorite and Colac Granite yielded ages between 241-250 Ma confirming a mid-early Triassic setting. The age range supports previous works that aligned Oraka Point as part of a progressively decreasing age trend from east to west within basement terranes along the Southland coast. Nd isotopic ratios indicate Oraka Point being strongly affiliated to the Longwood Suite with data fields having a clear overlap. Sr isotopic ratios were less conclusive to an affinity with the Longwood Suite and exhibited a wider spread of ratios, possible indicating an as yet undescribed thermal event. The new data presented here has led to Oraka Point as being interpreted as deriving from magmas that share the volcanic arc signature of the primitive Brook Street Terrane. The data also shows evidence for a transition towards the evolved Gondwanan continental margin signature. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/7149">http://hdl.handle.net/10523/7149</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Oraka Point Southland 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 2017Galloway Creator An entity primarily responsible for making the resource Galloway, James Robert (James) 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 Igneous Petrogenesis of Plutonic Rock at Oraka Point, Southland Subject The topic of the resource Igneous geology "LA-ICP-MS Brook Street Terrane Igneous isotopic ratios Longwood Suite New Zealand Oraka Point plutonic Southland zircon dating https://theses.otagogeology.org.nz/files/original/6870cc58c5f609699075a05dcf32d6af.pdf 1f4ca4f4faae541b6ef0f14f03c69e5b 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 (((166.896830153942 -45.5692202092565,166.933581438918 -45.5711851829177,166.928399066234 -45.5940123755103,166.893837383282 -45.5904959874,166.896830153942 -45.5692202092565))) Author last name Last name of the Author Dwight Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Scott, J.M. Abstract The Abstract for this thesis The Broughton Arm Meta-Peridotite is thought to represent a multiply metamorphosed ultramafic cumulate intrusion within Central Fiordland. This unit was first recognised by the QMAP Fiordland mapping program but has not been studied until now. The ultramafic body outcrops as a two oblate lobes trending north-south, encased in a thin hornblendite rim. It is situated within Early Paleozoic metasedimentary rocks that are thought to be a part of Deep Cove Gneiss (Takaka Terrane). Evidence for a cumulate origin is seen through bulk rock analysis, which return Mg# values of 78 – 79, far below that of mantle peridotite values. The primary metamorphic mineral assemblage (M1) includes olivine, enstatite and magnetite, and is overprinted by tremolite, chlorite, serpentinite, ± magnesite ± talc ± smectite ± anthophyllite, these conditions reflect ~amphibolite facies conditions. Extremely variable olivine Mg# (78 – 93) across the outcrop suggests it was also lithologically heterogeneous. The hydrous mineralogy likely reflect a fluid-rich metamorphic event (M2). The age of M1 is unknown, but it is tentatively correlated with a metamorphic event in the Carboniferous that has been documented from published titanite grains within the Deep Cove Gneiss in nearby Vancouver Arm. The M2 event may be associated with the extensional tectonics that lead to the rifting of Zealandia from Gondwana, in the amphibolite facies adjacent (~200 m) Doubtful Sound Shear Zone. The presence of this metamorphosed ultramafic unit provides evidence for (probable) Paleozoic high-temperature melting of the mantle under Fiordland. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Central Fiordland Thesis description Number of pages, maps, CDs, etc. 101 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 2016Dwight Creator An entity primarily responsible for making the resource Dwight, Thomas (Tom) 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 Evolution of the Multiply Metamorphosed Broughton Arm Meta-Peridotite, and Implications for the Wider Fiordland Region Subject The topic of the resource Metamorphic Geology Igneous Geology metamorphism peridotite ultramafic https://theses.otagogeology.org.nz/files/original/c8122ac95331b2bedcd88163976c7415.pdf dc8934c1ab73d099baa47beb8bc8cdfa 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 ((172.29277217379618 -42.059412438243626,172.290627751644621 -42.022224672831719,172.45682957846401 -42.020271904891452,172.459986571827102 -42.250956519757139,172.291865490327581 -42.255760681111717,172.29277217379618 -42.059412438243626)) Author last name Last name of the Author Sagar Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Palin, J.M. Toy, V.G. Abstract The Abstract for this thesis Distinctive basement gneisses of the Glenroy Complex and granitoids of the Mt. Cann Pluton and McKnee Intrusives are exposed in the Alpine Fault footwall, southeast Nelson, New Zealand. These rocks comprise tectonic blocks that form a foreland thrust system that has developed adjacent to a major restraining bend (“Big Bend”) in the Alpine Fault. The age of the Big Bend and its influence on exhumation of the Australian Plate are poorly constrained. This thesis addresses this issue through integration of conventional thermobarometry, U-Pb geochronology, and 40Ar/39Ar and fission-track thermochronology. The Glenroy Complex was intruded between 127.9–121.6 Ma and metamorphism occurred at 120.6 ± 0.9 Ma. Emplacement of the McKnee Intrusives occurred in two discrete episodes at 224.8 ± 2.6 Ma and 137.8 ± 0.7 Ma. These ages, in combination with whole-rock geochemistry, suggest that the McKnee Intrusives, Glenroy Complex and Mt. Cann Pluton are correlatives of the calc-alkaline Darran Suite, HiSY Western Fiordland Orthogneiss (WFO), and HiSY Separation Point Granite, respectively. Thus, the McKnee Intrusives and Woodham Orthogneiss have been displaced ~500 km along the Alpine Fault, while the Mt. Cann Pluton is autochthonous basement over which the former units have been tectonically emplaced. Using the Woodham Orthogneiss and WFO as piercing points, a slip-rate of 22–25 mm/year is calculated for the Alpine Fault, which overlaps existing long- and short-term estimates. This suggests that the Alpine Fault slip-rate has been approximately consistent for ~23 Ma. Thermobarometry indicates that peak two-pyroxene granulite facies and retrograde metamorphism occurred at 880 ± 70 °C and 4.5 ± 1.5 kb, and 663 ± 33 °C and 2.2 ± 0.9 kb, respectively. These results, and the lack of high-pressure garnet granulite facies assemblages, indicate that the Glenroy Complex experienced a clockwise pressure-temperature path. This suggests the Woodham Orthogneiss may represent magmas emplaced at a higher structural level that loaded the WFO causing garnet granulite facies metamorphism. After partial exhumation during mid-Cretaceous continental extension, which preceded rifting of New Zealand from Pacific Gondwana, the Glenroy Complex remained at ~350 °C from ~100–80 Ma. During Late Cretaceous–Middle Eocene continental extension, the Glenroy Complex was dissected by normal faults, which initiated cooling below ~350 °C at 16–28 °C/Ma. Faults in the western Glenroy Complex were active earlier than those in the east. Consequently, the Woodham Orthogneiss experienced differential exhumation – western and eastern parts cooled from ~350–200 °C between ~80–70 Ma and ~50–45 Ma, respectively. After reaching ~200 °C, the temperature-time paths of the Glenroy Complex began to converge, because differential exhumation was no longer occurring, and cooling slowed to ~4 °C/Ma, which lead to surface exposure at ~15 Ma. The slow, consistent cooling rate suggests that the Big Bend had not yet formed. Development of the Big Bend during the Middle Miocene resulted in exhumation of the Alpine Fault hanging wall, which loaded the Australian Plate creating a foreland basin. Hence, shortly after reaching the surface, the Glenroy Complex was buried by ~3 km of sediments, which caused rapid (~44 °C/Ma) reheating to ~80 °C that lasted for ~4 Ma, causing partial annealing of apatite fission tracks. A need to accommodate shortening associated with the Big Bend resulted in the Glenroy Complex being thrust over the foreland basin eastern margin during the Late Miocene–Early Pliocene. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/4715">http://hdl.handle.net/10523/4715</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. southest Nelson Thesis description Number of pages, maps, CDs, etc. xxiv, 316 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 2014Sagar Creator An entity primarily responsible for making the resource Sagar, Matthew William (Matt) 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 Geology, petrology and thermochronology of the Glenroy Complex and associated granitoids, southeast Nelson, New Zealand Subject The topic of the resource Igneous geology Metamorphic geology 40Ar/39Ar Alpine Fault Australian-Pacific plate boundary Big Bend Darran Suite exhumation Fission-track geochemistry Glenroy Complex gneiss Gondwana granite Granulites LA-ICP-MS metamorphism Nelson New Zealand Separation Point Suite thermobarometry thermochronology U-Pb zircon geochronology Western Fiordland Orthogneiss https://theses.otagogeology.org.nz/files/original/5e7099bd4d2a0d7c0302f4c780d082bc.pdf 00d8c01817a9e57dc9c3d2d73b1871bb 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 ((159.611042297072686 -76.747334877898581,159.59952317493844 -76.747155749513155,159.60364731091903 -76.734579204102531,159.603661093366412 -76.734537135035197,159.603904830747211 -76.733793115918758,159.607394514329997 -76.723131658338772,159.609728851011255 -76.715990491823646,159.61016919719259 -76.714642541076586,159.669508573285327 -76.715454613706413,159.708653558025588 -76.715982703436609,159.769040595726864 -76.716785488101934,159.767177065568944 -76.725839214640857,159.765644925912881 -76.733273801862936,159.762266606988646 -76.749637883736639,159.757407528486851 -76.749565288902389,159.665259214356865 -76.748170937708153,159.611042297072686 -76.747334877898581)) Author last name Last name of the Author Hood Hills Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student White, J.D.L. Abstract The Abstract for this thesis Jurassic fragmentation of Gondwanaland initiated the widespread voluminous outpouring of tholeiitic magma that is recorded on four continents. In Antarctica the Ferrar Supergroup, which outcrops along the length of the Transantarctic Mountains, formed within a wet failed rift during this break-up. It includes the extensive Ferrar Dolerite sills and dykes, and the extrusive Kirkpatrick flood basalt, and explosive volcanic deposits of the Mawson Formation. The Allan Hills, in southern Victoria Land, provides excellent exposure of these volcaniclastic deposits and was the site of study for this project. A small area was mapped in detail to determine the mode of origin of a part of the Mawson Formation and its relationship to the recently described 'phreatocauldron' in the nearby Coombs Hills. The Mawson Formation in the Allan Hills has previously been interpreted as part of a regional lahar field that formed as a precursor to Kirkpatrick flood-basalt eruption. Structural relationships and componentry of the Mawson Formation in the area, supplemented with results of coal vitrinite analysis, are difficult to reconcile with a laharic origin. During field work three different lithofacies were defined; a) thick, structureless, lithic-rich ponded pyroclastic density current deposits, b) several block-rich explosion or lag breccia horizons, and; c) a diatreme-like breccia-filled conduit (Ninnis Neck), one of the sources of other Mawson Formation deposits. These deposits are here interpreted to have formed within a phreatomagmatic vent complex, created by the coalescence of multiple vents similar to and including Ninnis Neck. Phreatomagmatic activity was fuelled by Fuel-Coolant-Interaction (FCI) as Ferrar Supergroup magmas intercepted water-saturated sedimentary materials of the Beacon Supergroup. Abundant peperite fragments formed by incomplete FCI, involving mingling of Beacon Supergroup clastic debris with magma preceding explosive fragmentation. Peperitic margins on basaltic dykes provide further evidence for involvement of wet sedimentary debris. Ninnis Neck was formed by upwards-directed tephra jets late in the overall complex's history. Recycling of tephra within individual vents, such as Ninnis Neck, was important in slowing the 'drying out' process and lengthening explosive activity. Growth of the Allan Hills vent complex occurred by lateral expansion facilitated by repeated failure of Beacon Supergroup strata along the margins due to volcanic and/or tectonic activity. The vent complex is interpreted to be relatively shallow, indicated by the limited sampling depth of accidental lithic clasts. The style of volcanism expressed in the Allan Hills of a shallow, possibly broad phreatomagmatic vent complex is comparable to that of the nearby Coombs Hills, and appears to have been widespread through much of the area covered by Kirkpatrick la vas now exposed in the Transantarctic Mountains. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Victoria Land south Antarctica Allan Hills Antarctica Thesis description Number of pages, maps, CDs, etc. viii, 107, [22] leaves : col. ill., col. 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 2004Hood_Hills Creator An entity primarily responsible for making the resource Hood Hills, Simone Belinda. Date A point or period of time associated with an event in the lifecycle of the resource 2004 Title A name given to the resource Wright dykes : a geochemical study of the dyke-forming rock types of the Wright Valley, Southern Victoria Land, Antarctica Subject The topic of the resource Volcanology Igneous geology Structural geology mafic volcaniclastics magma Mawson Formation phreatomagmatic volcanic complex https://theses.otagogeology.org.nz/files/original/f85520e0eb43266068d4a9c41e908b60.pdf 594ecbd8b0b41a855daaf3a1db6508d4 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 ((176.333460732912329 -37.663987423543418,177.005428982437024 -37.86470324877925,175.703755616851822 -39.367886940547812,175.514151721838346 -39.347112241207078,175.431716503745633 -39.227295538289717,176.333460732912329 -37.663987423543418)) Author last name Last name of the Author Rowland Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Sibson, R. Abstract The Abstract for this thesis The Taupo Volcanic Zone (TVZ) is a young (~ 2 . Ma) arc-related region of continental · extension at the southern end of the Havre Trough, characterised by intense volcanism, and geothermal activity. Extension (predominantly orthogonal) is accommodated by a structurally and magmatically segmented translithospheric rift structure: the Ruaumoko Rift System, (RRS). The varying trends of extensional structures lie perpendicular to least principal str·ess trajectories in a locally heterogeneous stress field with normal dip-slip as the predominant fault mechanism. Within the onshore RRS, three 1"' order rift segments from SW to NE (S1, S2, S3) with characteristic length scale - 65 km are recognised, one of which (S2), is further partitioned into 2"d order segments of length ~ 20 km. Major accommodation zones coincide with active rhyolitic calderas (Taupo Caldera, Okataina Caldera) between the 1 '' order rift segments. Although the TVZ is currently the most active rhyolitic centre on Earth, producing c. 0.3 m3/s magma since 340 ka, convective heat transfer by aqueous fluid transport, (4200 ± 500 MW channelled through over 20 geothermal fields), is thought to be four times that transferred through volcanic eruption. Significant volumes of solutes (silica dominant) are therefore likely to be transported and redeposited within the seismically defined 6 - 8 km thick ~onvection zone, affecting permeability, rock strength and hydromechanical behaviour. Hydrological modelling within the TVZ has generally assumed flow distributed throughout a uniform rock mass or isotropic permeability within different rock layers, with topographically driven flow dominant in the near surface. This, despite the evidence from borehole data and from fossil hydrothermal systems (e.g., greywacke-hosted vein system at Kuaotunu, Coromandel) for concentrated large-volume channel flow along faults and extension fractures. Hydrothermal fluid focussing is of particular importance to the exploration industry in its search for · epithermal mineralisation, while the presence of structurally controlled directional permeability has important implications for the exploration for, and extraction of, geothermal fluids. This dissertation therefore considers structural and physical controls on fluid redistribution. It is argued that stress-controlled directional permeability characterises TVZ hydrology, with fluid focussing important near the base of the convection system and locally within cover sequences. The rifting process, in concert with large-volume volcanic·· eruptions and magrnatism, has generated, and continues to modify, a heterogeneous crustal assemblage and permeability structure. Two simple rift-related hydrological regimes are recognised: (1) Horizontal hydraulic connectivity in rift segments. Juxtaposed assemblages of highporosity pyroclastic rocks and lake sediments, low-porosity lavas, low-porosity greywacke basement, and most likely dikes in various stages of cooling, form variably linked cr2-elongate fluid compartments because of static fault-fl1,1id and dike-fluid interactions, enhancing flow along strike. Dynamic fault-fluid interactions and dikefluid interactions also drive along strike flow (e.g., 1922 Taupo swarm, 1987 Edgecumbe earthquake). Aftershock migration in the 1987 Edgecumbe sequence suggests that transient post-rupture permeabilities could exceed the typical bulk permeability in geothermal systems by several orders of magnitude. (2) Vertical hydraulic connectivity in accommodation zones. Interaction between offset rift segments induces tensile stress concentrations in accommodation zones, generating and maintaining a localised dilation zone. Additionally, damage zones at the lateral tips of seismogenic scale normal faults and interaction between fault splays should enhance vertical structural permeability in these regions. Accommodation zones may have developed above reactivated NW -trending basement structures; in which case, formation of vertical pipe-like conduits is probable under the current stress regime. Porosity destruction through mineral deposition occurs within boiling zones in the geothermal systems (e.g., Ohakuri) and is inferred near the base of the convective zone throughout the rift system. This, coupled with the expected increase in low-porosity rock types with depth (greywacke, intrusions, unfractured andesite), suggests that focussed flow exploiting structural 111 ,I ,,1 permeability will predominate at depths approaching the base of the convection system. Localised overpressured fluid compartments are likely to develop under these conditions, leading to episodic fault-valving through distributed fault-fracture meshes, with subsequent self-sealing. The peak in seismic swarm events at commensurate depths throughout the rift system (4 - 6 km) may relate to this process. The spatial distribution of geothermal plumes within the RRS has previously been described as , 'uniform' and similar to the pattern produced by the heating of a fluid saturated isotropic porous medium from below. However, pattern inspection demonstrates that the plumes are not uniformly distributed, notwithstanding a local area of regular spacing coincident with the highheat flux low-fault density Taupo-Reporoa Basin. Departures from uniform spacing can be explained by rift-related fluid redirection and, to a lesser extent, exploitation of caldera-related structural permeability. Moreover, the Taupo-Reporoa Basin, bounded by seismogenic-scale normal faults, contains a thick sequence of low-density low-porosity pyroclastic rocks, beneath which basalt sill formation seems likely. The regular spacing of plumes in this region may therefore reflect the presence of a localised sill at depth, which acts as a hotplate heating the overlying fluid saturated porous medium. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Taupo Volcanic Zone Thesis description Number of pages, maps, CDs, etc. xv, 262 p. : ill. (some col.), maps (some col., some folded) ; 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 2001Rowland Creator An entity primarily responsible for making the resource Rowland, Julie V. (Julie Varina) Date A point or period of time associated with an event in the lifecycle of the resource 2001 Title A name given to the resource Hydrothermal fluid redistribution in a magmatic continental rift : the Ruaumoko rift system, Taupo volcanic zone, New Zealand Subject The topic of the resource Structural geology Igneous geology Volcanology continental rift fluid movement hydrothermal fluids magmatic continental rift magmatism rifts Ruaomoko Rift System https://theses.otagogeology.org.nz/files/original/75b5f961d259e77ab56d70cfa3fb8830.pdf 0807399922b65521b24443691f74fdcb 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 (((170.609321054418956 -45.455228026503654,170.611023917892567 -45.452763714561065,170.716139093469394 -45.531125784359006,170.609321054418956 -45.455228026503654)),((170.321698845852012 -45.867905864741019,170.169807260542541 -46.14620484708496,169.747845574527219 -46.19021751020783,169.904071956453322 -45.874492024406827,169.881739752211161 -44.930247273080035,170.609321054418956 -45.455228026503654,170.321698845852012 -45.867905864741019))) Author last name Last name of the Author Németh Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student White, J.D.L. Reay, A. Abstract The Abstract for this thesis The Miocene Waipiata Volcanic Field (WVF), New Zealand, is an eroded phreatomagmatic volcanic field. Three different types of vent or vent complex were recognized. Vent-filling deposits comprising predominantly lava, preserved in the form of plugs, necks, lava lake remnants, lava flows, or dykes, were classified as Type 1 vents. Type 1 vents are inferred to be the remnants of scoria cones, most of them with thin basal phreatomagmatic pyroclastic deposits. Vents represented by predominantly pyroclastic infill are classified as Type 2 vents. Type 2 vents are inferred to have been the substructures of phreatomagmatic tuff ring/maar volcanoes, many of which may have had associated scoria cones. Type 3 vent complexes are groups of closely spaced or overlapping vents, with voluminous preserved lava flows. Type 3 vent complexes are the remnants nested maars and tuff rings with associated magmatic explosive and effusive products. Pyroclastic rocks of most of the Waipiata vents record initial phreatomagmatic explosive activity fuelled by groundwater followed by Strombolian-style eruptions. Erosion rates for the WVF are 5 to 50 m per million years. Cenozoic sedimentary cover was widespread and still complete ( e.g. 200 – 400 m thick Oligocene marine units) at the time of volcanism, although over much of the field no Cenozoic sedimentary rock units remain today . Vent alignments largely follow the basement structural pattern of the Otago Schist, defining NESW and NW-SE trends. The longest vent alignment, traceable in ~ 30 km, coincides with and is parallel to the largest fault zone in the Otago region, the NW-SE trending Waihemo- fault zone. The total volume of magma erupted in the WVF is estimated to have been ~ 9 to 40 km^3 DRE. A systematic compositional sequence exists at each volcano, with initial phreatomagmatic eruptive products being differentiated tephrite and phonotephrite composition, whereas subsequent lava flows and dykes are of primarily basanite. Basanite was parental to the tephrite and phonotephrite. Basanite generated beneath WVF appears to have “failed” to reach the surface, instead being captured en route and stored to produce tephrite phonotephrite via 15-25 % crystal fractionation of olivine and clinopyroxene. Many attempted eruptions of parental basanite "failed", and that each successful eruption at the surface involved both a newly-injected basanite from depth, and a transected and entrained remnant of melt evolved from magma captured at shallower depths from a preceding "failed" eruption. Significant amount of magma was underplated beneath or injected into the crust of the WVF. The Otago crust is density and rheologically stratified, and in the Miocene lay within a mild extensional (strike- slip) tectonic regime; this combination was responsible for the entrapment of magma at various levels in the Waipiata – Dunedin region. The WVF-wide trend in magma evolution at individual vents has also been demonstrated from the mild extension-related Late Miocene Bakony- Balaton Highland Volcanic Field (BBHVF), Hungary. Recognition of this pattern at two unrelated fields may suggest that initial injection, with subsequent entrainment to produce dual-source monogenetic eruptions may be common in intracontinental alkaline basaltic volcanic fields. It is suggested that the lithospheric density and rheological structure, together with the state of stress, play an important role in fostering magma injection and entrapment in areas where the crust is 1) strongly density stratified, 2) relatively thin, 3) hot (high heat flow), and 4) the crustal stress regime mildly extensional, preferably with strike slip movements. These conditions were shared by the WVF and the BBHVF, with the result that magmas, processes of storage and differentiation, and ultimate eruption and volcano formation were in many ways remarkably similar. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Waipiata Otago north Thesis description Number of pages, maps, CDs, etc. 2 v. : ill. (some col.), maps (1 folded, col.) ; 30 cm. + 1 computer disk. 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 2001Nemeth Creator An entity primarily responsible for making the resource Németh, Károly, 1969- Date A point or period of time associated with an event in the lifecycle of the resource 2001 Title A name given to the resource Phreatomagmatic volcanism at the Waipiata volcanic field, Otago, New Zealand Subject The topic of the resource Volcanology Igneous geology Structural geology Map basanite erosion Hungary maar New Zealand phreatomagmatic scoria tephrite vent https://theses.otagogeology.org.nz/files/original/836fdc7023cebe4d711743e0c42a62e6.pdf 1442c6c519ba6dbd380899c010bd6192 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 ((166.953199937504422 -46.262588680125532,167.333227804747679 -45.605702691953184,167.724360227187248 -44.869476354585174,168.051614409440219 -44.919890560696075,167.251214671966778 -46.335178624757489,166.953199937504422 -46.262588680125532)) Author last name Last name of the Author Smith Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Cooper, A.F. Abstract The Abstract for this thesis This report is a synthesis of the Eastern Fiordland Belt. The Eastern Fiordland Belt is bounded to the west by a fault system defined: (i) At Lake Te Anau by the fault which separates the Paleozoic Lake Roxburgh Tonalite to the west from the Eastern Fiordland Volcanics to the east (King 1984). (ii) At Lake Manapouri by a 50 m wide mylonite zone parallel to the eastern shore of South Arm (Turner 1937a). (iii) In the Grebe Valley by the Grebe Fault (Powell 1992). The eastern boundary lies beneath Cenozoic sediment in the Te Anau and W aiau Basins and is probably faulted (Turnbull and U ruski 1993). The Eastern Fiordland Belt is divided into three main rock groups. (1) The Eastern Fiordland Volcanics consist of a scattered series of exposures of low grade, typically greenschist facies, metavolcanic sediments, dykes, and lavas (e.g. Loch Burn Formation). The unit, dominated by volcanic sediments, crops out largely as fault-bound slivers. New occurrences of non-volcanigenic and volcanic-derived metamorphosed sediments are described from the Snag Burn, and the northern shore of South Fiord, Lake Te Anau. In the Lake Monowai area a metasedimentary xenolith within the Western Southland Orthogneiss, and metavolcanic conglomerate float boulders from the Lill Burn are included within the Eastern Fiordland Volcanics. The Eastern Fiordland Volcanics have calcalkaline affinity and are Mid-Triassic in age (Kimbrough in King, 1984). Correlation of the Eastern Fiordland Volcanics with the Largs Terrane (north eastern Fiordland) and Paterson Group (Stewart Island) is suggested on the basis of similar petrography, geochemistry and tectonic setting. (2) The Western .Southland Orthogneiss is the most volumetrically significant group in the Eastern Fiordland Belt. It consists of a suite of amphibolite facies orthogneisses, typically hornblende-plagioclase-biotite dioritic and gabbroic assemblages. In the Lake Monowai area the Western Southland Orthogneiss contains an unusual peralkaline A-type granite, informally termed the Tangney Granitoid Gneiss (Powell, 1993). Detailed geochemical and petrological investigation of the Western Southland Orthogneiss in the Lake Monowai area suggests that the Tangney Granitoid Gneiss is derived from the same magmatic protolith as the surrounding mafic orthogneiss via fractional crystallisation. (3) The Eastern Fiordland Granitoids consist of an intrusive suite of Cretaceous granitoid rocks which post-date regional amphibolite facies metamorphism. The granitoids are generally massive, non-foliated, and either granite or granodiorite composition. The Eastern Fiordland Granitoids are correlated with the northern part of the Rakeahua Batholith (Stewart Island) and the Separation Point Batholith (Nelson region). The bases of these correlations are the similar Cretaceous ages, petrography, geochemistry and structural position. The Early Cretaceous magmatic and tectono-metamorphic history of Eastern Fiordland has important implications for the evolution of the relative plate motions and Me so zoic terrane accretion along the New Zealand segment of Gondwana. In particular there are implications for Early Cretaceous collision, metamorphism and formation of the zone of enigmatic rocks, fault bounded between New Zealand's Eastern and Western Provinces, termed the Median Tectonic Zone. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/3230">http://hdl.handle.net/10523/3230</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Fiordland Thesis description Number of pages, maps, CDs, etc. 110 leaves (some folded) : ill. (some col.), maps some col.) ; 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 1993Smith_B Creator An entity primarily responsible for making the resource Smith, Bruce Alexander. Date A point or period of time associated with an event in the lifecycle of the resource 1993 Title A name given to the resource Eastern Fiordland geology Subject The topic of the resource Igneous geology Metamorphic petrology Fiordland Fiordland Complex Lake Manapouri Lake Monowai Lake Te Anau tectonics https://theses.otagogeology.org.nz/files/original/0e3deab3f1035eb7f19a1f4adfeca2d7.pdf b33fb7a5f450f569c62215115cefb6be 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 ((161.301669644104408 -77.903250131472902,161.176623976081089 -77.903986808103056,161.175966465343151 -77.902143184156301,161.167108352889613 -77.877251309256465,161.308033053877068 -77.875251639617318,161.316036961821965 -77.875135909040566,161.385368619156054 -77.874123718749161,161.390151357286271 -77.884033168102974,161.357194941527723 -77.891201136751889,161.301669644104408 -77.903250131472902)) Author last name Last name of the Author Morrison Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Coombs, D.S. Cooper, A.F. Norris, R.J. Koons, P. Abstract The Abstract for this thesis At Terra Cotta Mountain, in the Taylor Glacier region of southern Victoria Land, basement granitoids of the Granite Harbour Intrusives are overlain by approximately 1000 metres of Beacon Supergroup sediments. A thick (237 metre) Ferrar Dolerite sill is intruded along the unconformity between the basement and overlying sediments. Numerous other Ferrar Dolerite dikes intrude the Beacon Supergroup and represent later phases of intrusion. In-situ differentiation in the sill has involved the removal of phenocrysts from the upper zone of the sill by crystal settling, and the migration of the differentiated liquid to form a granophyric zone approximately 40 m below the top of the sill. However, differences between the calculated bulk composition of the sill and the composition of the chilled margins indicate that the sill did not crystallize from a single, homogeneous intrusion of magma. The apparent inhomgeneity of the magma may be the result of flow differentiation, or the later intrusion of a more phenocryst-rich magma. The sill is truncated by the intrusion of a large dike. The dike interior is distinguished from the margins by a relative depletion in Cr. A model is favoured whereby the large dike acted as a magma conduit to higher levels. The low Cr concentrations in the interior of the dike reflect a depletion of Cr in the magma with time. Geochemistry indicates a trend towards a more basic composition from the oldest to youngest dolerite intrusion. Crystal fractionation may account for much of the geochemical variation between the intrusive events. However, the poor correlations between many trace elements are consistent with the additional involvement of open system processes. The "decoupling" of Cr and highly incompatible elements is similar to the theoretical behaviour predicted for the products of a periodically replenished, tapped and fractionating magma chamber. The Ferrar Dolerite samples from Terra Cotta Mountain exhibit large ion lithophile element-enrichment and depletions in Nb, Sr, P and Ti. The similarity of the trace element characteristics of the dolerite from Terra Cotta Mountain with those of other Ferrar Group rocks from the central Transantarctic Mountains and northern Victoria Land, as well as with the Tasmanian Dolerites, supports current ideas that the trace element signature of the Ferrar Group is inherited from a uniformly enriched mantle source region. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Terra Cotta Mountain Antarctica Victoria Land Thesis description Number of pages, maps, CDs, etc. ix. 266 p., ill., 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 1989Morrison Creator An entity primarily responsible for making the resource Morrison, AD Date A point or period of time associated with an event in the lifecycle of the resource 1989 Title A name given to the resource Ferrar dolerit intrusions at Terracotta Mountain, suothern Victoria Land, Antarctica. Subject The topic of the resource Igneous geology Antarctica Ferrar Dolerite Taylor Group Terra Cotta Mountain Windy Gully