1 10 4 https://theses.otagogeology.org.nz/files/original/0ff4e90adc2f6fcd3c9c773fc6263da4.pdf 5ffa0e46f9e022501daa032e99f34429 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 ((168.324185158000091 -46.590544009999974,168.324049425000112 -46.592147125999986,168.323314835000019 -46.600719178999952,168.318124152000109 -46.600528732999976,168.315823832000092 -46.600442774999976,168.311861722000117 -46.60029586,168.270814986000119 -46.598762532999956,168.272078617000034 -46.584858797999971,168.273326607000058 -46.571134626999935,168.273585456000092 -46.568270304999942,168.273651605000055 -46.567556534999937,168.274153460000093 -46.562016493999977,168.274390102000098 -46.559417117999942,168.276695517000121 -46.559499676999963,168.29353061200004 -46.560099362999949,168.300554472000044 -46.560349990999953,168.304371169000092 -46.560482666999974,168.326681021000013 -46.561270885999932,168.324483232000034 -46.58705497699998,168.324475441000118 -46.587149285999942,168.324395751000111 -46.588074279999944,168.324389444000076 -46.588150624999969,168.32437311800004 -46.588348223999958,168.324185158000091 -46.590544009999974)) Author last name Last name of the Author Elder Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Reay, A. Abstract The Abstract for this thesis In the Bluff area lower green schist facies Greenhills Group rocks of the Brook Street terrane derived from a Permian volcanic arc have been intruded ~ by igneous bodies inducing contact metamorphism. Facies of contact metamorphism are observed as pyroxene hornfels facies in assimilated xenoliths in a hybrid rock zone, further out from the intrusions hornblende hornfels are observed. At a distance of 800 m from the intrusive contacts albite-epidote facies of contact metamorphism are observed in metabasaltic dykes. Evidence for this facies comes from the mineral assemblages in the metabasalt dykes which have cut vertically through Greenhills Group metasediments very soon after the tilting of the Greenhills Group bedding associated with the intrusion of the large igneous bodies. The intrusive bodies are the Flat Hill gabbronorite and the Ocean Beach diorite which show a distinct difference in the bulk rock chemistry with the diorite appearing as a· more evolved rock. Dyke intrusion of microgabbro, quartz diorite and hornblende pegmatite is part of late stage activity associated with the cooling of the large igneous~ bodies. Granitic dykes present post date the intrusion of the large igneous bodies and the late stage dyke activity. The age of the Flat Hill gabbronorite is given as 265 M a, the oldest recorded rocks of the Brook Street terrane. - --l J Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Flat Hill Bluff Peninsula Thesis description Number of pages, maps, CDs, etc. 71 p. : 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 1994Elder Creator An entity primarily responsible for making the resource Elder, Damon Jon. Date A point or period of time associated with an event in the lifecycle of the resource 1994 Title A name given to the resource Geology of Flat Hill-Ocean Beach, Bluff Peninsula Subject The topic of the resource Areal geology Bluff Peninsula Brook Street plutonics Southland Region https://theses.otagogeology.org.nz/files/original/cd307064e2865dbd5ab1f004001f4a61.pdf 533ac794f9c43f263f1eaad17704eb87 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 Webster Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Reay, A. Abstract The Abstract for this thesis The Greenhills Ultramafic Complex lies about 12km to the south-west of Invercargill and occupies approximately 15km2 of the n~rthernmost corner of the Bluff Peninsula. It is part of the Brook St terrane" and is believed to represent the roots of a Late Permian island arc volcanic chain that has had its upper portion subsequently removed by erosion. Mossman(1970) undertook a comprehensive study of the area as the basis of a PhD thesis and concluded that the Greenhills Ultramafic Complex represents the remains of a shallow level magma chamber that was open to the atmosphere and of a hydrous nature. The Greenhills Ultramafic Complex consists of a layered structure consisting of ultramafic rocks at the base and a gabbroic portion at the top. The sequence of minerals observed is consistent with fractionation of a basaltic magma with olivine predominating and being accompanied by residual chromite in the first rock type to occur: dunite. Later in the sequence clinopyroxene begins to crystallise and the rock type becomes a wehrlite. Next in the sequence of minerals is orthopyroxene, however its modal proportion is far lower than most other layered ultramafic complexes. Skaergaard (Wager and Deer 1939)contained websterite rather than wehrlite the difference being the predominance of orthopyroxenes in the rock rather than the clinopyroxenes as occurs at Greenhills. Repeated intrusions of more felsic magma as dikes up through the base and into the intrusion pre-empted the fractional crystallisation that was occurring so that an upper gabbroic layer was deposited at the top of the sequence. Mossman concluded that the composition of the magma was basaltic and that it had affinities between calc-alkaline and tholeiitic, which at the time of his investigation was quite an innovative idea. ~] _]! _] -] -] J J J J J J J ] J l l This suggestion is investigated to try to determine whether this is a viable source magma for the observed fractionation sequence and the conclusion is that it is a viable mechanism for forming the minerals that comprise the complex. The difference between this study and that of Mossman is that it is suggested here that the corrugated contact between the wehrlite and dunite was caused by small scale convection cells eroding the base of the magma chamber and depositing the debris by gravitational settling elsewhere in the magma chamber and this process results in the rhythmic layering observed here . This is a similar, process to that which occurred in the Skaergaard intrusion (Irvine 1987) except that the small convection cells do not occur as a consequence of double diffusive convection but simply that the magma chamber has too low a roof to allow the development of a convection cell that is the full width of the magma chamber. A time constraint has been put on the age of the intrusion by some recent work and the collection of ages for surrounding metasediments allows a clearer picture top be obtained on how and when the complex developed. The geochemical bias of this project has meant that confirmation could be obtained for multiple intrusions of magma throughout the complex because in the past the evidence had been entirely petrographical. A clearer understanding of how the Greenhills Ultramafic Complex developed and of the processes that occurred inside it while it was still crystallising. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Greenhills Thesis description Number of pages, maps, CDs, etc. 98 leaves, [1] folded leaf of plates : ill. (some col.), col. map ; 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 1994Webster Creator An entity primarily responsible for making the resource Webster, Glen Robert. Date A point or period of time associated with an event in the lifecycle of the resource 1994 Title A name given to the resource Greenhills revisited : an investigation into the geochemistry of the Greenhills Ultramafic Complex Subject The topic of the resource Geochemistry Bluff Peninsula Brook Street Greenhills Ultramafic Complex https://theses.otagogeology.org.nz/files/original/2c6a2178f020432efd5a0981051d667f.pdf da0a791e4262f9e5aade0eb50b02553e 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 ((168.241420761000086 -46.558084479999934,168.228468796000016 -46.557569936999982,168.227368622000085 -46.557525779999935,168.228399821000039 -46.543594594999945,168.229578571000047 -46.543632895999963,168.236634082000023 -46.543870775999949,168.242579599000123 -46.544068310999933,168.274727274000043 -46.545129520999978,168.273646543000041 -46.559365045999982,168.271143324000036 -46.559265550999953,168.268067209000037 -46.559143208999956,168.262250297000037 -46.558911635999948,168.241420761000086 -46.558084479999934)) Author last name Last name of the Author O'Loughlin Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Reay, A. Abstract The Abstract for this thesis Exposed along a three kilometre stretch of coastline on the southern extremities of the South Island, New Zealand are a suite of calc-alkaline to tholeiitic ultramafic and gabbroic rocks which form the southern portion of the Greenhills Ultramafic Complex (GUC). This complex consists of a layered series of dunite, wehrlite, olivine-clinopyroxenite and gabbro of Earliest Triassic age (247Ma), which intrude Lower Permian meta-sedimentary lithologies of the Greenhills Group. Accompanying the intrusion of the complex is a narrow contact metamorphic aureole which decreases rapidly in grade from pyroxene-hornfels facies metamorphism, directly adjacent to the body, to regional prehnite-pumpellyite facies metamorphism, with distance from the contact. The layered series of the GUC is stratigraphically divisible into an upper gabbroic portion of both non-cumulate and cumulate gabbroic rocks, and a lower ultramafic portion of dunite, wehrlite and olivine-clinopyroxenite. The lower ultramafic portion shows well-developed accumulate structures and textures that are typical of stratiform cumulate intrusions. Widespread slumping in the layered series in addition to discrete zones of intense brecciation, faulting, and multiple phases of dyke injection indicate recurring conditions of instability during the evolution of the complex. Textural, mineralogical, and chemical evidence suggests that two gabbro suites comprise the upper gabbroic portion. Namely, a cumulate suite (Shipwreck Gabbro) that is closely related to the lower ultramafic portion, and a non-cumulate (Barracouta Point Gabbro) suite, which is thought to have crystallised from a mixed magma. Whole rock chemistry of the layered series indicates a clear magmatic fractionation trend through dunite to gabbro, consistent with chemical fractionation from a basaltic parental magma. This trend is characterised by a systematic decrease in magnesium content with a concordant increase in silica, aluminium, calcium, and alkalis. A similar fractionation trend is exhibited by the evolution of the primary mineral phases olivine, clinopyroxene and plagioclase through the layered series. The theory that the GUC may have been derived by dry partial melting of the mantle wedge is supported by the similarity in trace element chemistry between the GUC and N-type Mid Ocean Ridge Basalt (MORB). Similarly, the trace element chemistry correlates well with recent basalts and basaltic andesites from the Tonga-Kermadec Island Arc, indicating that present day active ocean-ocean island arc subduction zones may serve as closely representative models for the evolution of remnant arcs such as that inferred for the GUC. The development of a strong tholeiitic to calc-alkaline island arc chemistry in the GUC is typical for magmatic bodies throughout the Brook Street Terrane, which are thought to represent the remnant of an ancient island arc system. A comparison of chemistry between the GUC and that of the Blashke Islands Alaskan-type intrusion from SE Alaska, indicates that these two bodies have been de1ived by fractional crystallisation of a closely similar parental magma, and thus, the GUC can be classified as a Alaskan-type Intrusion. The Greenhills Ultramafic Complex was produced as the result of crystal settling during fractional crystallisation of a basaltic parental magma produced by dry melting of the mantle wedge in an ocean-ocean island arc subduction zone. Modification of the layered body by magmatic slumping, mingling and brecciation and faulting depict recurring conditions of instability within the pluton which is considered typical of island arc subduction zones. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/5630">http://hdl.handle.net/10523/5630</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. Bluff Southland Thesis description Number of pages, maps, CDs, etc. 115 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 1998OLoughlin Creator An entity primarily responsible for making the resource O'Loughlin, Benjamin, 1977- 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 Geology of the southern portion of the Greenhills ultramafic complex Subject The topic of the resource Igneous petrology Bluff Peninsula Greenhills Complex layered intrusions ultramafics https://theses.otagogeology.org.nz/files/original/25c7c1eeea66f7f274cd106a5541b495.pdf 4f218cc2e5d1ec1dbce62833379de8c6 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 ((168.213944620626648 -46.503055367676893,168.291425198663717 -46.506850039084377,168.269467965246491 -46.56576677324562,168.198178840135995 -46.559741340039096,168.213944620626648 -46.503055367676893)) Author last name Last name of the Author Cross 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 The Greenhills Complex is a composite ultramafic to mafic layered igneous intrusion located on the Bluff Peninsula, 30 km south of Invercargill. Two principal lobes range from dunite at their base through olivine clinopyroxenite to gabbro. On the basis of crystallisation sequence, mineral composition and melt inclusion compositions (Spandler et al., 2000), the intrusion appears to have formed from primitive hydrous basaltic magmas in feeder chambers beneath an island arc volcanic complex as part of the Permian Brook Street Terrane. Dunite of the south lobe is well exposed in the Greenhills Quarry. The dominant primary mineral is cumulus olivine with minor cumulus chromian spinel, intercumulus clinopyroxene and rare orthopyroxene and plagioclase. A series of dykes of varying composition cross cut the dunite, forming small zones of plagioclase-rich rocks. A number of zircon grains extracted from a plagioclase-rich felsic dike intruding the dunite of the Greenhills complex have been dated using LA-ICP-MS analysis of U/Pb isotope ratios to an age of 261.5 ± 2.3 Ma. This is consistent with the minimum age of 246 ± 10 Ma obtained from K/Ar dating of hornblende in gabbroic rock by Aronson (1968) and the age reported by Spandler et al. (2003) of 265 Ma obtained by Kimbrough et al. (1992) using U/Pb isotope ratios. Spandler et al. (2000) report the occurrence of platinum-group minerals (PGM) in chromian spinel at one location just south of the Greenhills dunite quarry. LA-ICP-MS analysis of chromian spinel in this study has revealed ppb concentrations of PGE and ppm concentrations of gold in a small number of chromian spinel grains. Olivine in the dunite is fractured and partially replaced by serpentine and carbonate. XRD analysis of nine alteration rims of the dunite and one white vein has identified calcite, chlorite, chrysotile and other rarer phyllosilicates. L.O.I. analysis reveals the average volatile component of the dunite to be 7.74 wt% while bulk rock volatile element (CNS) analysis reveals the average concentration of naturally occurring carbonates in the dunite to be 0.6 wt% per sample with some samples having as much as 4.5 wt% carbonate and up to 11.5 wt% H2O. Recent studies have shown that natural rates of carbonation of olivine-rich peridotite (Keleman & Matter, 2008) and serpentinite mine tailings (Wilson et al., 2009) are much faster than previously thought. These rates should be further enhanced in the subsurface because the carbonation reactions are exothermic and, in the case of serpentine-bearing rock, lead to increased porosity. If the dunite has sufficient fracture permeability at depth, it is conceivable that CO2 could be injected at a flow rate sufficient for heating due to carbonation to balance cooling due to advection and diffusion in order to maintain an optimal temperature for rapid reaction. Alternatively the natural rates of carbonation of olivine at the surface can be enhanced by simply crushing and spreading on the Earth’s surface (Schuiling and Krijgsman, 2006). When mixed with a slow release fertiliser, crushed dunite could potentially act as a cheaper substitute for lime. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/2043">http://hdl.handle.net/10523/2043</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. Green Hills Southland Thesis description Number of pages, maps, CDs, etc. vi, 86 leaves : ill. (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 2011Cross Creator An entity primarily responsible for making the resource Cross, Anthony James. Date A point or period of time associated with an event in the lifecycle of the resource 2011 Title A name given to the resource Greenhills Complex Dunite: Mineralogy, Petrology, Geochemistry and Potential for Carbon Sequestration Subject The topic of the resource Petrology geochemistry Bluff Peninsula Brook Street Terrane carbon sequestration chromian spinel dunite geochronology Greenhills Complex igneous complex laser ablation inductiv petrology platinum group elements platinum group minerals U/Pb dating ultramafic zircon