1 10 2 https://theses.otagogeology.org.nz/files/original/7f971e7ea11eaa4070d38e1d63d2d4ca.pdf 5cf8ab101baace6e637d3ac176ca3245 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 ((167.272391025425435 -45.7166744240455,167.401345597718063 -45.725945405317304,167.392192626017447 -45.79337520995994,167.261557277289398 -45.789011287239646,167.272391025425435 -45.7166744240455)) Author last name Last name of the Author Grieve Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student Prior, D.J. Scott, James M. Abstract The Abstract for this thesis Emplacement of the Median Batholith along the Gondwana margin has been argued to have resulted through magmatic and tectonic processes. Analysis of the Grebe Mylonite Zone (GMZ) an amphibolite facies Early Cretaceous ductile shear zone, provides new insight into the kinematics, conditions and processes that played a role in its deformation and exhumation. The GMZ forms the boundary between the Outboard Median Batholith and Eastern Province and the Inboard Median Batholith and the Western Province in Fiordland, New Zealand. Three units derived from Darran Suite magmas, (1) meta-diorite, (2) meta-granodiorite and (3) meta-granite dominate the GMZ and exhibit a north striking steeply west dipping foliation and moderately south plunging lineation. The grain boundary migration (GBM) mechanism dominates quartz recrystallisation and is inferred to represent deformation temperatures of ~ 600?C and stresses of 6 to 22 MPa derived from paleopiezometry of recrystallised quartz size. Crystallographic preferred orientation (CPO) data of quartz, plagioclase and hornblende were obtained using electron backscatter diffraction (EBSD). Hornblende [100] a-axes align preferentially perpendicular to foliation with [001] c-axes aligned parallel to lineation, producing an orthorhombic symmetry that provides no information on shear sense. Plagioclase fabrics are sub divided into three groups: [a](c), hybrid-A and hybrid-B, from these fabrics it is interpreted that crystal plastic slip was accommodated on the (001), (010) and the previously unrecognised (011) planes. Weakening of the plagioclase CPO from east to west is thought to indicate a shift towards grain boundary sliding (GBS) diffusion creep deformation mechanisms. Quartz CPOs show predominantly Y-maxima fabrics, [0001] c-axis directions plot within the plane of foliation indicating < a > prism slip at ~ 600?C. Progressive rotation of quartz CPO fabrics towards the west are thought to represent an increasing temperature/strain rate gradient towards the western contact between the GMZ and the Puteketeke Pluton. Interpretation of quartz fabrics indicate an overall regional oblique sinistral west side down sense of motion relative to the Western Province. However, conflicting kinematics are observed between the units of the GMZ, strain partitioning in a dominantly coaxial strain geometry is proposed as the mechanism for the difference in kinematics. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/5983">http://hdl.handle.net/10523/5983</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. Grebe Mylonite Zone Jaquiery Stream central Fiordland Thesis description Number of pages, maps, CDs, etc. xvi, 161 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 2015Grieve Creator An entity primarily responsible for making the resource Grieve, Jason William Date A point or period of time associated with an event in the lifecycle of the resource 2015 Title A name given to the resource Deformation processes, kinematics and conditions of the Grebe Mylonite Zone, Jaquiery Stream, central Fiordland, New Zealand. Subject The topic of the resource Structural Geology Cretaceous Crystallographic Preferred Orientation (CPO) deformation conditions Fiordland mylonite zone plagioclase quartz https://theses.otagogeology.org.nz/files/original/4cd41cd263febc6c9896b0fab71cc822.pdf c832afa652d1f338b8000fd21d89aaeb 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 ((169.390912193000077 -43.773307220999975,169.377374785000029 -43.763932274999945,169.388307604000033 -43.755735631999983,169.388788090000048 -43.755375320999974,169.389268949000098 -43.755697210999983,169.391667898000037 -43.757303000999975,169.393438840000044 -43.758488332999953,169.400781631000086 -43.763402231999976,169.40227927400008 -43.764404315999968,169.405249183000024 -43.766391347999956,169.433091448000027 -43.785009184999979,169.437644424000041 -43.788051965999955,169.425937 -43.797541544999952,169.406620031000102 -43.78417953,169.390912193000077 -43.773307220999975)) Author last name Last name of the Author Green Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Koons, P. Abstract The Abstract for this thesis Petrogenesis of the system Na20-CaO-MgO-Al203-Si02-H20 (NCMASH) is examined at 18 to 30kbar, 700°C for the purpose of modelling quartz-bearing eclogitic gneiss. Phases synthesised are quartz, kyanite, paragonite, omphacite, Na-amphibole and talc. Trioctahedral Na-mica is not synthesised in NCMASH and Na-amphibole is stable in water-saturated conditions. Omphacite progressively changes composition from jadeite49diopsides1 at 18kbar to jadeite7odiopside3o at 30kbar and Na-amphibole becomes enriched in the glaucophane end member, although the range is compressed such that all compositions are more than 95% glaucophane, 5% tremolite. At 18kbar the stable assemblage is omphacite+paragonite+Na-amphibole+quartz+H20 and probably garnet. Kyanite appears in a quartz+H20-saturated system between 18 and 22kbar via the reaction paragonite+garnet+Na-amphibole=kyanite. Above 24kbar, paragonite is lost via the reaction paragonite=2omphacite+jadeite exchange (NaA1Ca_tMg_t)+kyanite+H20 and NaAlCa-tMg_l becomes unbuffered. Na-amphibole is lost between 27 and 30kbar by the reaction Na-amphibole (near glaucophane composition)=2omphacite+0.64jadeite exchange+ talc. The paragonite and Na-amphibole breakdown reactions in the NCMASH experimental system are compatible with observations of correlative natural assemblages. A petrogenetic grid derived from the NCMASH experimental results is applic:able to quartzofeldspathic and quartzbearing basic compositions in the eclogite facies. The petrogenetic grid is integrated with others interpreted from natural paragenetic relationships showing the relationships between different quartz-bearing eclogite facies terrains in terms of chiefly continuous reactions. Haast Schist at Mariners Peak in south Westland was metamorphosed during the Mesozoic Rangitata Orogeny producing an amphibolite facies assemblage in quartzofeldspathic schist. Compositional variation with increasing metamorphic grade across a structural section is interpreted in terms of 3 continuous equilibria involving the consumption of epidote, quartz, NaK_t and AlAl(Fe,Mg)_tSLt and the production ofplagioclase, garnet, CaAlNa_tSLt. TiSLt. MnFe_l and CaFe_l· The major compositional zoning of garnet is CaFe_l enrichment toward the rim and is compatible with pro grade growth in the matrix assemblage. During the Rangitata Orogeny, the tectonic burial of schist now exposed within 5km of the Alpine Fault was rapid and isothermal, at least for the final lOkm of burial to about 20-30km. Rangitatan deformation was a continuum of synmetamorphic, nappe-forming, ductile Matukituki folding and later, largely post-metamorphic, ductile Manorburn folding. After Rangitatan tectonism ceased, the geotherm relaxed and the crust was thinned. The high grade schist did not re-equilibrate during uplift, but pegmatite with a cooling age of 60-65Ma indicates localised partial melting at a deeper level. Mid to late Cenozoic Kaikouran wrenching and uplift associated with the Pacific-Australian plate boundary folded and sheared the schist, but reequilibration was limited to incipient biotite growth in the cores of some folds. A zone of mylonitisation adjacent to the Alpine Fault is bounded by a strain rate contour and the brittle-ductile transition, both of which evolved as rapid uplift advected heat. The total Kaikouran exhumation at the Alpine Fault is 10-17km and declines rapidly in a lOkm wide zone adjacent to the fault. Relative uplift was accommodated by spaced slip parallel to schistosity without retrogressive reaction. At present, much of the tectonic shortening may be accommodated by thickening of the upper crust. At Mariners Peak the Rangitata Orogen involved rapid vertical tectonics, but did not generate a thermal regime compatible with eclogite facies metamorphism. In contrast, it is likely that eclogite facies conditions currently exists under the Southern Alps. The thermal regimes of both orogens must be accounted for if a single model encompasses all continental collisions. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Moeraki River Westland Thesis description Number of pages, maps, CDs, etc. xi, 277 p. : 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 1992Green Creator An entity primarily responsible for making the resource Green, David Colin, 1960- Date A point or period of time associated with an event in the lifecycle of the resource 1992 Title A name given to the resource High pressure petrology and evolution of the Haast schist, New Zealand Subject The topic of the resource Petrology Haast Schist mylonite zone petrology