1 10 6 https://theses.otagogeology.org.nz/files/original/f57202c72a162ced67fccdafdeaaf679.pdf 533af0e8fd8acab70985118085958fb1 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 ((170.386311975000012 -45.219667209999955,170.385649708000074 -45.227336381999976,170.38087069200003 -45.282484380999961,170.281612151000104 -45.280108060999964,170.278141247000121 -45.267563154999948,170.274156802000107 -45.253138011999965,170.266416873000026 -45.225111572999936,170.264574289000052 -45.21843783199995,170.255355363000035 -45.184996155999954,170.389050153000085 -45.188020043999984,170.386311975000012 -45.219667209999955)) Author last name Last name of the Author Tenney Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Coombs, D.S. Abstract The Abstract for this thesis The Flat Hill area covers approximately 115 km2, and is located northeast of Hyde, Otago. The schist basement in this area constitutes part of the eastern portion of the Triassic to Middle Jurassic Otago schists, and is sporadically overlain unconformably by a Tertiary transgressive- regressive sequence. This sequence is in turn unconformably overlain and intruded by members of the Waipiata Volcanic Formation. Quartzofeldspathic lithologies constitute the bulk of the schist types in the mapped area. Thin horizons of metachert interbedded with the quartzofeldspathic rocks comprise the only other distinctive lithology. Pistacite content of epidotes from schists in the present area range from Ps 19.2 to 29.6. Muscovites are all 2M polymorphs, and silica contents (SiiV cation contents 6.52-7.01) indicate that they are phengitic members of the muscovite-celadonite solid solution series. Chlorites are typically brunsvigite and ripodolite. All newly formed amphibole is actinolite, and garnet in metacherts is zoned with relatively spessartine-rich cores and increasing grossular and almandine components towards the rim. Curious micaceous minerals referred to as green and brown "biotites" occur in some quartzofeldspathic lithologies from the Flat Hill area. Optically and geochemically similar minerals were investigated in schists from Brighton, and a metachert from West Blackstone Hill. The brown "biotite" may represent a transitional, interlayered chlorite-biotite phase formed during progressive metamorphism. X-ray studies and geochemistry indicate the green "biotite" may be a unique> submicroscopically interlayered mi;neral comprised of chlorite and phengite components. In the light of these curious minerals, it remains unclear as to whether the present area and certain other parts of eastern Otago are in the chlorite or biotite zones. The schists in the present area were subject to three synmetamorphic and one post-metamorphic folding phase generations. Phase I is correlated I with the deformation period which produced large scale recumbent folds throughout the Haast Schist terrain. No macroscopic Phase I structures ( were recognized in the present area owing to the scarcity of mesoscopic structures associated with this phase, and also because of subsequent disruption by Phase II folding. Macroscopic, antiformal Phase II folds are inferred on the basis of overturning of Phase I lineations, and symmetry and vergence of mesoscopic Phase II folds. These large structures may be refolding limbs of earlier Phase I macrostructures. Phase Ill structures are limited to mesoscopic folds and lineations, and Phase IV structures consist of fault-related kink folds and flexures. Tertiary sediments are comprised of the marine Tiroiti Formation and the terrestrial Wedderburn Formation. The Tiroiti Formation consists of unconsolidated, variably glauconitic, bioturbated, scarcely fossiliferous, well-sorted sands and silty sands. Boulders of biocalcarenite (one algaebearing) were found, and are considered to be associated with the upper part of the Tiroiti Formation. An alternating intratidal nearshore and a deeper water, marginal marine environment is inferred for the Tiroiti Formation. A lagoonal-shoreface environment is envisaged as a likely depositional environment for the biocalcarenites. The Wedderburn Formation consists of a variety of alternating quartz sands, muddy lenses, lignites, and conglomerates ranging from very fine, well-sorted sands to gravels. The silicification of Wedderburn sediments appears to be intimately associated with overlying flow remnants. The Wedderburn Formation is thought to represent a retreating shoreline with both fluvial and shoreline processes playing important simultaneous roles in the sediment deposition. Remnants of the Waipiata Volcanic Formation cover an area of approximately 14 km2 in the area ·studied. Included are: ohawaiite, mafic phonelite, nepheline trachybasalt, mafic nepheline trachyandesite, nepheline hawaiite, and alkaline olivine diabase. Four new analyses from the Flat Hill area are compiled along with published analyses of roe~ from the Waipiata Volcanic Formation. The following lineages are recognized on the basis of geochemistry: mildly undersaturated, sodic lineages; moderately undersaturated, sodic lineages; relatively potassic, variably undersaturated ( lineages; and a highly undersaturated,sodic lineage." A distinctly alkali- poor olivine basalt also occurs, and may result from a unique lineage. Due to the ubiquity of lherzolite nodules in rocks of the Waipiata Volcanic Formation, they are considered to represent high pressure lineages of mantle derivation as distinguished from the more diverse Dunedin magmas which have been at least partially derived as a result of crustal level differentiation processes. Examination of Mg-values and variation diagrams for lherzolite-bearing alkaline rocks of the Waipiata Volcanic Formation has revealed examples of magmas representing both possible primary melts or slightly fractionated derivations of such liquids, and related, more highly evolved high pressure derivatives. The mineralogy of a lherzolite nodule from the Flat Hill mafic phonolite suggests latest equilibration temperature and pressure at 870-991 °C and 12-16 kilobars, respectively. These conditions should serve to establish a minimum depth of fractionation and derivation for the host mafic phonolite. The frequent association of megacrysts with the magmas of the Waipiata Volcanic Formation is important when considering the fractionation of the different high pressure lineages which have been recognized. The presence of titaniferous ferroan paragasite megacrysts in the Flat Hill mafic phonolite implies an amphibole-dominated fractionation model for the high pressure derivation of the evolved members of the moderately undersaturated, sodic lineages. Removal of titanomagnetite may play a subordtpate role in the fractionation processes controlling the derivation of both the mildly and the moderately undersaturated,sodic lineages of the Waipiata Volcanic Formation. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Flat Hill Thesis description Number of pages, maps, CDs, etc. 156 leaves : illus. map(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 1977Tenney Creator An entity primarily responsible for making the resource Tenney, Stephen Michael. Date A point or period of time associated with an event in the lifecycle of the resource 1977 Title A name given to the resource Geology of the Flat Hill area, Otago, New Zealand. Subject The topic of the resource Map Igneous petrology Metamorphic geology Sedimentary petrology Structural geology metachert quartzofeldspathic schist Waipiata Volcanics https://theses.otagogeology.org.nz/files/original/2d7b27fadb190bc781f62b800a597b32.pdf 7ffcea9458df1b66ef9bd80ea1411068 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 ((168.417304580585125 -45.153316362439639,168.272038230924636 -44.792974796932569,168.658304091917216 -44.709261509929178,168.828564358117575 -45.052879697941094,168.417304580585125 -45.153316362439639)) Author last name Last name of the Author Paterson Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Henley, R.W. Norris, R.J. Coombs, D.S. Abstract The Abstract for this thesis The Glenorchy lode field, comprising scheelite (CaWo4) bearing quartz lodes, is one of many gold tungsten and antimony mineralized lode fields within the Haast Schist of the South Island of New Zealand. The lode fields in the Otago schists are more abundant and were more productive than those elsewhere in the Haast Schist. The Otago schist belt is composed mainly of metasediments (psanunitic and pelitic schists) with subordinate amounts of metavolcanic rock and metachert; metamorphic grade ranges from pumpellyite-actinolite facies to the biotite zone of the greenschist facies, while amphibolite facies rocks occur in the Alpine schists adjacent to the Alpine Fault to the northwest. The origin of the epigenetic Au and W mineralization has been debated since the early 1900's when the model invoking passage through the schist of metalliferous emanations from an underlying magma was in vogue. However, the absence in the schists of suitable igneous rocks, that could be interpreted as being spatially and temporally associated with the mineralization, prompted other ore genesis models. Secretion of the Au and W from the country rocks by meteoric waters was proposed, but since the 1960's, :geological opinion has favoured an origin connected with regional metamorphism. Both geochemical and petrological approaches are utilized in this thesis in an attempt to elucidate the controls on W mineralization at Glenorchy. In the Glenorchy field, the lodes consist of quartz-calcitescheelite veins in crushed, folded, sulphide-bearing schist bounded by clay selvages. Scheelite is sporadically distributed in the quartz veins. Ore shoots are parallel to the dip and strike of the Glenorchy Lode, the most productive lode in the field. The lodes dip 15-30° NE, cutting the SW-dipping schistosity at an angle of 60-70°, and with the subsidiary lodes comprise a subhorizontal flattened network. It is tentatively concluded that the lodes originated by passage of ore-forming fluids along pre-existing normal faults developed during the early stages of uplift of the schist pile. Both syn- and post-mineralization deformation is recognized within the lode. The petrography and mineralogy of the unaltered Mt Judah schists are described, and this section forms the basis for later characterization of the hydrothermal alteration. Psarnmitic and thin-bedded (alternating pelitic-psarnmitic) schists are dominant on Mt Judah, and are within pumpellyite-actinolite facies. East of Bonnie Jean Creek the schists are in greenschist facies, and the abundance of pelitic schists and greenschists increases eastwards. From the composition of paragonitic muscovite, and existing experimental data on the upper stability limit of pumpellyite, the temperature of metamorphism in the Mt Judah schists 0 was about 400 c, although oxygen isotope data suggest the temperature could have been as high as 445°C, The petrography and mineralogy of the altered schists are described, and the changes in minimal abundance and mineral composition with hydrothermal alteration are discussed. The Mineralogical alteration zone is generally 1.5-2 m \dde and is characterized by alteration of ea-silicates (amphiboles, pumpellyite, epidote) to aggregates of chlorite and calcite, serpitization of albite, and deposition of sulphides, kaolinite, and calcite. Metamorphic sulphides, stilpnonelane, sphene and rutile were als0 altered DY the hydrothermal fluids. The mineral compositions of schist minerals were not affected, except. for chlorite which displays an increased compositional range in the altered schists, with a tendency for increased MgO and decreased FeO contents. Two alteration zones arc recognized - sericite-carbonate zone and a marginal zone. Major element and trace element analyses of the bulk schists in four traverses perpendicular to the lode show that the altered schists are depleted in CiiO, Fe 2 o3 , sio2 , Sr, and Y, and enriched in co2 , K2o, H2o, FeO, S, Rb, Cs, W, As 1 and Sb relative to the unaltered schists. Mass balance calculations suggest the ea and Sr in the scheelite, the Fe in the sulphides, and half the Si in the quartz within the lodes originated from the altered schists adjacent to the lode. S, C, As, W, Sb, Rb, Cs, and some Si were introduced to the lodes in the Mt Judah area by the ore-forming fluid from a source deeper in the schist pile. Oxygen isotope analyses of schist and lode minerals are presented. Adjacent to the lode there is an aureole up to 10 m wide in which the values of the quartz, albite, and muscovite are high relative to those in the unaltered schists. Oxygen isotope fractionations indicate a temperature range o.f 3500 -2800 C for h 018 . hn t mineralization, o18 enrichment aureole suggests the ore-forming fluid was previously in equilibrium with schists at deeper levels in the pile at temperatures exceeding 420°C~ The isotope composition of the fluid (oo18 == 8.sro0) is compatible with both metamorphic and magmatic derivation. The isotope aureole and the decrease in oxidation state of the altered schists (indicated by increased 2+ . Fe /total Fel have resulted from interaction between the schists and relatively large volumes of fluid transported up\va:t'ds in major conduits in the schist pile. Because of the lack of spatial relationship between mineralization and contemporaneous igneous activity,it is concluded that the mineralization was a consequence of various processes associated with burial metamorphism. The feasibility of such an marigin is examined. Dehydration and decarbonation reactions during metamorphism in schisto of higher grade than greenschist facies are capable of producing sufficient fluid consisting mainly of H2o, with considerable co2 component. It is suggested that the fluid was trapped in the schist pile during burial, and that an increase in permeability consequent upon microhydraulic fracturing induced by rapid uplift, allowed migration of the fluids to existing planes of weakness (faults) which were then opened up as main channel ways by further hydralic fracturing. Metal- enriched horizons as sources of Au, W, and Sb are considered not essential to ore genesis, as pervasive leaching of the metals from all lithologies in the schist belt during mineral transformation reactions associated with progressive metamorphism is all that is required for development of potential ore-forming fluids. The antipathetic distribution of Au and W mineralization is a consequence of depositional rather than source parameters. Rich scheelite deposits were formed in fractiones cutting ea-mineral enriched rocks such as psammitic schists of pumpellyiteactinolite to lower greenschist facies, as a result of reaction between the fluid and wall rocks. Hydrogen metasomatism associated with sericitization of feldspar may have resulted in gold deposition, together with minor scheelite deposition,' at lower crustal levels and higher temperatures. Consequently, the ore-forming fluid depositing scheelite at higher crustal levels would be relatively depleted in Au. The lode fields appear to be preferentially developed near hinge - zones of macroscopic nappes, but the orientation of the lode structures is related to the NE,-SW.-directed extensional tectonic regime existing after the major phases of deformation and metamorphism. The ore genesis model developed here is compared with the models for Au and w mineralization in other metamorphic belts throughout the world. It is concluded that in most of the other belts, the ore-forming vii metals and fluids originated within the metasediment-metavolcanic piles, but that igneous intrusion rather than regional metamorphism was the driving force for the mineralization process. The ore genesis model may be useful in a general sense in future mineral exploration in the Haast Schist, but the patterns of chemical and mineralogical variation around the lodes are probably too restricted to have any immediate application. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/5233">http://hdl.handle.net/10523/5233</a> OURArchvive access level Open Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Glenorchy Thesis description Number of pages, maps, CDs, etc. xx. 266p. Ill. Plates. Maps in text. 30cm. 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 1977Paterson Creator An entity primarily responsible for making the resource Paterson, Colin J. Date A point or period of time associated with an event in the lifecycle of the resource 1977 Title A name given to the resource A geochemical investigation of the origin of scheelite mineralisation, Glenorchy, New Zealand. Subject The topic of the resource Mineralogy Geochemistry Metamorphic geology gold mineralisation Otago Schist oxygen isotopes quartz veins scheelite mineralisation https://theses.otagogeology.org.nz/files/original/d2dc14f4f42721cbbc64d577cb85d732.pdf 9a45eab207110a04876eb210d3d57421 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 ((167.750947518000089 -45.672537530999932,167.771232940000118 -45.673209100999941,167.804444767000064 -45.674299777999977,167.852921214000048 -45.675878882999939,167.977451905000066 -45.679834625999945,167.974903611000059 -45.731002883999963,167.974233196000114 -45.744460572999976,167.974212637000051 -45.744878888999949,167.972531214000014 -45.77860390799998,167.934033066000097 -45.777525256999979,167.875973756000121 -45.775875945999985,167.856026041000064 -45.775302456999952,167.857748234000042 -45.750481171999972,167.799490304000074 -45.74869285699998,167.764810292000107 -45.747613443999967,167.744806195000024 -45.746986053999933,167.750947518000089 -45.672537530999932)) Author last name Last name of the Author Houghton Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Landis, C A Abstract The Abstract for this thesis The Takitimu Group consists of Lower Permian basaltic, andesitic and rhyodacitic lava flows, primary and redeposited pyroclastic rocks and epiclastic sediments. Two suites of intrusive rocks cut the Takitimu Group strata in the central Takitimu Mountains. These are informally named here the White Hill and MacKinnon Peak Intrusive suites. This thesis is principally a study of sedimentation, volcanism, mineralogy and petrology of the Takitimu Group, mineralogy and petrology of the intrusive rocks and low grade metamorphism. The Takitimu Group forms the oldest beds exposed on the western limb of the Southland Syncline. The Takitimu Group crops out as a homoclinal sequence in the central Takitimu Mountains. Strata strike north-south and are partly overturned, dipping predominantly between 80°W and 85°E. These strata are subdivided here into five formations described in ascending stratigraphic order. The Brunel Formation consists of predominantly red-brown mudstone and silt-laminite with minor intercalated tuff, litharenite, hyaloclastite and near the top of the formation thin basaltic and rhyodacitic lava flows. The Chimney Peaks Formation is made up of interbedded volcaniclastic arenites and rudites and basaltic and rhyodacitic lava flows. Basaltic lava flows, sills and pillow lavas predominate in the Heartbreak Formation. The MacLean Peaks Formation is a sequence of volcaniclastic sediments and interbedded basaltic and andesitic lava flows. The Elbow Formation consists of predominantly volcaniclastic breccias and conglomerates and subordinate andesitic and basaltic lava flows or sills, and litharenites. Stratigraphic columns are provided for each formation and a detailed column is provided for a 1 200 m sequence in the upper MacLean Peaks Formation. Fourteen lithological groupings (or lithofacies) were recognised in the Takitimu Group within four broad categories: (1) massive and autobrecciated lava flows, (2) pyroclastic and hyaloclastic rocks, (3) epiclastic and reworked pyroclastic arenites and rudites, (4) lutites. Lava flows form slightly less than one quarter of the 14 km sequence in the central Takitimu Mountains. Brecciated lava flows and pillow lavas are common. Individual flows rarely exceed 100 m in thickness but may be separated by as little as 2 m of sediment. Category two consists of basic tuffs and lapilli tuffs, rhyodacitic vitric tuffs, agglomerates, hyaloclastites and massive tuff breccias. The volcaniclastic arenites and rudites show typical sedimentary structures described from classical turbidite terrains. Normal graded- and reverse graded-arenites are recorded. The former closely resemble nonvolcaniclastic turbidites. Normal graded, reverse-to-normally graded and massive rudites are present. Category four is subdivided into silt-laminites and red-brown mudstones. The former are principally distal turbidites, the latter are the products of 'background' sedimentation. The lithofacies occur in six associations which are related to a model for sedimentation and volcanism in modern island-arc systems. In this model the active volcanic chain is flanked by volcaniclastic aprons on the margins of fore-arc and marginal basins. Submarine and subaerial volcanism produces thick sequences of lavas and pyroclastic rocks near the vents. Lahars, avalanches, pyroclastic flows and epiclastic mass flows transport clastic material onto the apron where it is redistributed by mass flows and particularly turbidity currents. Pyroclastic fall deposits and wedges of hyaloclastite and pillow lava also accumulate on the aprons. The volcanic rocks form a reasonably continuous series of calcalkaline rocks (with a possible break in composition at 62-66% silica). They show weak iron-enrichment on an AFM diagram. The suite is subdivided here on the basis of silica content with the boundaries taken to coincide with major mineralogical changes. Basalts and basaltic andesites range in texture from uniformally fine-grained to porphyritic and holocrystalline to near hyaline but strongly plagioclase-phyric basalts predominate. Basalts contain combinations of plagioclase, diopsitic augite, olivine, magnetite and volcanic glass. Andesitic lavas are typically weakly porphyritic and contain phenocrysts of plagioclase, augite, hypersthene and rarely magnetite in a groundmass of plagioclase, augite, pigeonite, magnetite and occasionally volcanic glass. A single hornblende andesite is recorded from the top of the Elbow Formation. Rhyodacites contain plagioclase phenocrysts set in intergranular quartz, alkali feldspar, magnetite and ilmenite. Twenty-five new chemical analyses are presented here as are representative full and partial analyses of plagioclase and pyroxenes and full analyses of magnetites. The Takitimu Group shows a number of features typical of calcalkaline suites namely it is high in alumina, low in titania, shows little or no absolute iron enrichment and the majority of the analysed specimens are quartz-normative. Harker variation diagrams reveal Al(2)O(3), FeO*, MgO, CaO and MnO decrease with increasing silica, Na(2)O and K(2)O increase and TiO(2) and P(2)O(5) remain approximately constant. The chemistry of aphanitic and porphyritic basalts is widely different. The aphanitic rocks are characterised by high total iron and Na(2)O and the porphyritic rocks by high Al(2)O(3) and CaO. Some trace element abundance in ten rocks were determined by spark source spectroscopy; other trace elements were determined by X-ray fluorescence in eleven rocks. The analysed specimens are preferentially enriched in light REE and show low abundances of nickel and chromium relative to alkaline and tholeiitic suites. The porphyritic basalts lack positive europium anomalies suggesting they are not partly cumulus. A crystal fractionation model is presented for basaltic to andesitic lavas. The chemistry of rhyodacitic lavas cannot be generated by removal of observed phenocryst minerals from the andesites and an independent origin is favoured for the acidic rocks. The White Hill Intrusives consist of coarsely-crystalline predominantly concordant bodies of gabbro, diorite, basic granophyre and aplite. The suite was probably emplaced over a wide time interval from Middle Permian to Upper Triassic and may have formed from several distinct but similar magma batches. Differentiation of the sills has taken place partly in situ and partly prior to emplacement. Sixteen new chemical analyses of specimens are presented here together with electron microprobe analyses of plagioclase, pyroxenes, magnetite, hornblende and olivine. The White Hill Intrusives show strong similarity in chemistry and mineralogy to the volcanic rocks of the Takitimu Group. The White Hill Intrusives also closely resemble basic intrusive rocks of the Longwood Complex, MacKay and Tasman Intrusives which intrude strata correlative of the Takitimu Group. The period of time in which the White Hill Intrusives were emplaced was therefore a period of extensive intrusive activity throughout the Brook Street terrain. The MacKinnon Peak Intrusive suite is mineralogically distinct from all other intrusive rocks in the Takitimu Mountains. The suite consists of a swarm of high-alumina basaltic dykes charged with cognate xenoliths and phenocrysts of anorthite, salitic pyroxene and tschermakitic hornblende. The phenocryst mineralogy suggests these phases crystallised under conditions of high P(H(2)O). Chemical analyses of four dykes and a xenolith are presented here, together with representative full and partial analyses of all mineral phases. The model for the formation of the MacKinnon Peak dykes presented in Chapter 6 postulates that crystal fractionation in a shallow-level magma chamber led to the formation of adcumulate layers which were overlain by a transitional zone of close-packed crystals with interstitial fluid. Disruption of the chamber and cumulus layers followed and the dykes were emplaced as 'crystal-mush' probably with the aid of retrogressive boiling and volatile streaming. Four hornblende concentrates from the dykes yield K/Ar cooling ages of 231-242 my. The Takitimu Group is subdivided into two metamorphic zones. The upper zone contains zeolite facies assemblages. Analcime, albite, chlorite, epistilbite, heulandite, laumontite, natrolite, stilbite, thomsonite and yugawaralite have been recorded from this zone. Prehnite-quartz occurs in shear zones and fractures in the upper zone. The lower zone contains prehnite-pumpellyite facies assemblages. Actinolite, albite, chlorite, epidote, prehnite and pumpellyite have widespread distribution in this zone. Hematite, sphene and andradite also occur in some rocks. Chemical analyses of most of the phases listed above are presented in Chapter 7. The degree of metamorphic reconstitution is variable and is nowhere complete. Textural evidence suggests reaction of volcanic glass with entrapped seawater has occurred forming chlorite and/or montmorillonite and presumably leaving fluid enriched in SiO(2), Al(2)O(3), Na(2)O and CaO. Ultimately the fluid chemistry evolved to a stage where albite and hydrated calcium aluminosilicate phases formed. Contrasting assemblages in and adjacent to shear zones and in the host rocks, in the central Takitimu Mountains, are a function of either reduced P(H(2)O)/P(total) or higher temperatures in the shear zones. The White Hill Intrusives were probably a major source of heat during metamorphism. The Takitimu Group probably experienced a variety of thermal gradients with an initial but short-lived period of high temperature gradients during plutonism followed by a longer period of burial under a moderate geothermal gradient. In the final chapter a synthesis and geological history for the volcanic and associated intrusive rocks is presented and comparison made with published models for the evolution of Tertiary-Recent sequences formed in the vicinity of present day island arcs. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/3991">http://hdl.handle.net/10523/3991</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. Takitimu Mountains Thesis description Number of pages, maps, CDs, etc. 2 v. : illus. maps (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 1977Houghton Creator An entity primarily responsible for making the resource Houghton, Bruce Frank Date A point or period of time associated with an event in the lifecycle of the resource 1977 Title A name given to the resource Geology of the Takitimu group and associated intrusive rocks, central Takitimu Mountains, western Southland, New Zealand Subject The topic of the resource Map Igneous petrology Metamorphic geology Sedimentology epiclastic rocks Permian lavas pyroclastic rocks zeolite https://theses.otagogeology.org.nz/files/original/e4a0dea3bd65426147608a887c296804.pdf f56c94fb02c3d40dba26e6568f421050 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 ((171.044311836751405 -44.116279021172488,171.088587346195197 -44.117266834042972,171.103378618880583 -44.161343771946399,171.039864816155216 -44.160747704552463,171.02722374613748 -44.172678591188038,171.003738861770557 -44.172270471483905,171.005543466451428 -44.158009582896362,171.044311836751405 -44.116279021172488)) Author last name Last name of the Author Hitching Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Advisers Who supervised/advised this student Landis, C.A. Abstract The Abstract for this thesis Argillitic metasiltstone, metagreywacke, conglomerate, chert, metavolcanics and marble comprise the Torlesse rocks at Kakahu. These rocks are situated forty kilometres north west of Timaru, cover an outcrop area of twenty five square kilometres, are overlain unconformably by Tertiary sediments to the south and east, and are separated from Tertiary rocks to the north and west by the Rapuwai fault. Metasiltstone and metagreywacke comprise approximately 60% and 30% of the Torlesse rocks of Kakahu respectively. These rocks belong to textural zone 2B, except for those on the far west of the field area, which are 2A. Pumpellyite is abundant in all metasiltstones and metagreywackes. Prehnite is common in the 2A rocks but occurs only spasmodically in those of textural grade 2B. Point counting indicates that the Kakahu metagreywackes are quartzofeldspathic and are broadly typical of Torlesse metagreywackes. The only sedimentary structure seen in these rocks is laminated, often graded, bedding. Conglomerate is uncommon and was found at only three localities. Pebbles are predominantly well rounded intrabasinal Torlesse-type siltstones, but rare chert, granophyre, and rhyolite pebbles were also found. Fourteen occurrences of chert are recorded, and these may be subdivided as follows: i) Bedded, coloured cherts up to 160 m thick. These cherts are bedded on a scale of 2- 50 cm, and grading and alternations with thin laminae of chloritic slate occur at several localities. These features suggest that these cherts are probably siliceous turbidites. A relict radiolarian texture is observed in some thin sections. ii) Non bedded, grey or yellow grey cherts from l m to approximately 20 m in thickness. iii) Red and pink cherts intercalated with hematitic metavolcanics and white marble in the lower Kakahu River gorge. Two lithologies of intercalated metavolcanics and marble crop out in the lower Kakahu River gorge. The westernmost lithology is a 140 m thick sequence of sixteen bedded units of tuffaceous greenschist, grey marble and metasiltstone. The second lithology which lies directly to the east of the former is 90.m thickness of intercalated poorly schistose hematitic metavolcanics·and pure white marble. In places the white marble is present as irregular lensoidal masses within the metavolcanics - these were probably originally masses of calcareous sediment which infiltrated into primary voids between submarine pillows. The Kakahu Marble is a 30 m thick, pure grey marble which has yielded a fauna of Pennsylvanian conodonts. Conodonts of the same age have also been obtained from the grey marble which is interbedded with tuffaceous greenschist and metasiltstone in the lower Kakahu River gorge. No other identifiable fossils were found in the Torlesse rocks of Kakahu. Three phases of folding are recognised. F1 folds are tight mesoscopic folds which are preserved only in the bedded cherts and interbedded metavolcanic and marble rocks. Macroscopic F2 folding was accompanied by the formation of the regional schistosity (S 2). S2 was macroscopically folded during F3 deformation. The resistant marker lithologies (i.e. cherts, intercalated metavolcanics and marbles, the Kakahu Marble) are traceable along strike for up to 500 m; their boundaries appear to have been tectonically sheared off. Evidence of transposition and shearing is ubiquitous in the metasiltstones and metagreywackes, and the rocks comprise a tectonic melange in the sense of Cowan (1974). Some marker lithologies have boundaries with metasiltstone that are parallel to sand laminae observed in the metasiltstone. As the only two fossil localities at Kakahu, which are 1 kilometre apart, are Pennsylvanian in age, and as one of these fossil localities is interbedded with typical Kakahu metasiltstone, it is likely that all the Torlesse rocks of Kakahu are likewise of Pennsylvanian age. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Kakahu Thesis description Number of pages, maps, CDs, etc. 93 leaves : illus. (part. col.) map (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 1977Hitching Creator An entity primarily responsible for making the resource Hitching, Keith David. Date A point or period of time associated with an event in the lifecycle of the resource 1977 Title A name given to the resource Torlesse geology of Kakahu, South Canterbury, New Zealand. Subject The topic of the resource Map Sedimentary petrology Structural geology chert marble Rapuwai Fault Torlesse Supergroup https://theses.otagogeology.org.nz/files/original/0e2eac5b9aab782d57946d1e9b0c05cb.pdf bc37b08ce84b9c21c6a96413b1c6604d 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 ((168.213377871000034 -46.565700191999952,168.214060116000041 -46.557405323999944,168.217821658000048 -46.511592170999961,168.218198352000059 -46.507015809999984,168.218319479000115 -46.505542745999946,168.245670756000095 -46.506568539999932,168.269926317000113 -46.507473603999983,168.276119789000063 -46.507701963999978,168.308518527000047 -46.508899737999968,168.31725596900003 -46.50922174599998,168.321683454000095 -46.50938255899996,168.34214192100012 -46.510131805999947,168.362239911000074 -46.510863331999985,168.375571644000047 -46.511346449999962,168.372649464000119 -46.54766768099995,168.372550423000121 -46.548880272999952,168.371264784000118 -46.564855757999965,168.369080545000088 -46.59192885899995,168.368697228000087 -46.596694074999959,168.368218649000028 -46.602622457999985,168.368137789000116 -46.60361047899994,168.366162357000121 -46.628096466999978,168.2360569330001 -46.623031932999936,168.208753472000012 -46.621949633999975,168.21201411800007 -46.582312442999978,168.213377871000034 -46.565700191999952)) Author last name Last name of the Author Graham Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? BSc(Hons) Abstract The Abstract for this thesis A segment of the Brookstreet terrain (Coombs et. al., 1976) is described from the Bluff Peninsula, Southland. The basement rocks include Lower-Permian volcanogenic sediments and dykes of the Greenhills Group with interbedded calcarenites and flows. The rocks are steeply dipping and are locally deformed into open, steeply-plunging folds. An intrusive body of gabbronorite with associated late-stage derivatives occurs in the Southern part of the area and is surrounded by a transition zone of partially assimilated metasediment and a wide metamorphic aureole. The metamorphic grade of the country rock is predominantly hornblende-hornfels facies but locally increases to pyroxene-hornfels facies. The gabbronorite is intruded along the Western coastline by a suite of quartz diorite and granitic dykes. Temperature estimates for the intrusive rocks are included and are derived from experimental data and microprobe analysis of pyroxene and magnetite-ilmenite pairs respectively. A cryptic variation trend in the gabbronorite is investigated. Previous geologic work on the Bluff Peninsula is summarised and the mutual relationships and possible genesis of the various intrusive bodies is discussed. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Ocean Beach Thesis description Number of pages, maps, CDs, etc. 130 leaves : illus., maps (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 1977Graham Creator An entity primarily responsible for making the resource Graham, I. J. Date A point or period of time associated with an event in the lifecycle of the resource 1977 Title A name given to the resource Geology of Ocean beach, Southland, New Zealand. Subject The topic of the resource Map Igneous petrology Metamorphic geology dyke gabbro-norite intrusion Greenhills Group https://theses.otagogeology.org.nz/files/original/9b849cc8e009331869325a2d57c6dc7a.pdf 40d0bdbe4b9c69e73feea2e419ee6db2 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 ((170.188408172110627 -46.053471126147116,170.211224774378337 -46.055459410881326,170.213191938413445 -46.084322600848004,170.209514818354336 -46.109713914512632,170.191020076296269 -46.150220670148563,170.144117716737156 -46.189160250394401,170.087512766991637 -46.209163460003133,170.075888375549596 -46.19553069616822,170.136481771809571 -46.151343063713625,170.173886612152529 -46.116791800585304,170.18570949240285 -46.086363526347618,170.187455077563243 -46.065497665836297,170.188408172110627 -46.053471126147116)) Author last name Last name of the Author Bejnar Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PGDipSci Advisers Who supervised/advised this student Norris, R.J. Abstract The Abstract for this thesis The southern most coastal exposure of Tuapeka Group rocks is in the Bull Creek area, south of Milton, south Otago. Four mapping units were separated because of sedimentological or structural differences. Massive homogeneous sandstones and siltstones are (from four point counted thin sections) dacitic feldspathic psammites. Related rocks include thick bedded sandstones, rhythmicly bedded siltstones and argillites with fossil worms, colour banded argillites and bedded radiolarian cherts. Black chert nodules from one area were studied geochemically. 2000 ppm tungsten and about 500 ppm native silver occur in these iron and manganese rich radiolarian chert cobbles. The rocks are metamorphosed to upper prehnite - pumpellyite to lowest pumpellyite - actinolite facies; they belong to textural zones 1 and 2A (after Bishop, l972A). Despite the low degree of metamorphism, the rocks are often structurally complex. Six phases of deformation have been identified. 1) Extensive soft sediment deformation caused sedimentary melange in some isolated areas. 2) Isoclinal folding and shearing disrupted the area. Because of the double deformation of the sedimentary melange areas, granules to blocks of the various lithologies are strewn around in an argillite matrix. This is mapped as a broken formation. 3) A deformation overturned the sequence. 4) Normal faulting occurred. 5) Low angle shear zones with well developed long quartz fibers formed. 6) The area was crossed by joints and veins. The placement of what is here labelled 3 and 5 are not definite; they each may have occurred one earlier. The principal quadratic extensions determined from deformed radiolaria are 1.34, 1.10 and 0.68. Most of the elongation probably occurred during phase 2. The geologic history and possible plate tectonic associations are discussed. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Bull Creek Thesis description Number of pages, maps, CDs, etc. 91 leaves : illus. map (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 1977Bejnar Creator An entity primarily responsible for making the resource Bejnar, Tor John Stark. Date A point or period of time associated with an event in the lifecycle of the resource 1977 Title A name given to the resource Geology of the Tuapeka group, Bull creek area, South Otago, New Zealand. Subject The topic of the resource Map Geochemistry Metamorphic petrology Structural geology chert textural zone Tuapeka Group