1 10 2 https://theses.otagogeology.org.nz/files/original/36347101a27a15b68905c727936dc7ea.pdf 9f617ebdfb01bd850084f858164a0898 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 ((168.209693133000087 -45.665156176999972,168.188347208000096 -45.664532452999936,168.186946168000077 -45.6613425099999,168.180039790000023 -45.645621837999954,168.163645185000064 -45.608280301999969,168.163984342000049 -45.608294340999976,168.126187456000025 -45.504027253999936,168.129684672000053 -45.5041328099999,168.194297864000077 -45.506042373999946,168.198291142000016 -45.506157237999957,168.198741855000094 -45.506171281999968,168.316475437000122 -45.544962533999978,168.343043887000022 -45.553694694999933,168.338410751000083 -45.615379730999962,168.337693856000101 -45.615351159999932,168.337080913000023 -45.624312624999959,168.336980158000074 -45.624367193999944,168.321991751000041 -45.632687198999974,168.276571844000046 -45.657879342999934,168.260794339000086 -45.666619754999942,168.22099839100008 -45.665478830999973,168.210260803000097 -45.665170406999948,168.209693133000087 -45.665156176999972)) Author last name Last name of the Author Hyden Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Coombs, D.S. Abstract The Abstract for this thesis The West Dome sector of the Dun Mountain ophiolite belt has been mapped on a scale of 4 inches to 1 mile (approximately 1:16000). The area covers approximately 200 sq.km. (80 sq. ml.) and has been subdivided into northwest - southeast trending structural units that are correlated with the terranes of Coombs et al.(1976a). Minor but significant variations from this trend occur. Major faults are present at the contacts of these units. The following stratigraphy (from northeast to southwest) is recognised at West Dome: A. CAPLES - PELORUS TERRANE: This terrane contains sedimentary and igneous rocks which are in fault contact. Local informal nomenclature is proposed for these strata at West Dome. Acton Downs melange: This unit comprises tectonic inclusions of meta-igneous rocks and minor sedimentary ones that have undergone at least one period of cataclasis, set in an obscure matrix. Gyzeh volcanics: They contain mainly non-pillowed metabasalts and together with the Acton Downs melange, probably represent part of a much dismembered ophiolite sequence. Diston stream sedimentary unit: It can be subdivided into a lower, mainly coarse grained sandstone assemblage, and an upper, mainly fine grained assemblage of thinly interbedded fine sandstone and mudstone. B. HUMBOLDT GROUP: This group occurs as a dismembered ophiolite sequence at West Dome, the ultramafic portion giving rise to well developed knocker topography. Red Mountain Ultramafite: This subgroup is almost completely serpentinised and is present as a melange. The tectonic inclusions are dominated by metagabbros and metadolerites, but minor metabasalts rare sedimentary rocks and albite amphibolites occur in a serpentinite matrix. The meta-igneous rocks are derived from the overlying Livingstone Subgroup but the sedimentary inclusions, some containing Atomodesma, are of unknown origin. Livingstone Subgroup: This subgroup has been divided into four informal units of which units (ii) - (iv) are considered to be stratigraphically continuous and directly comparable with the upper part of an ophiolite sequence. unit (i) comprises non-pillowed metabasalts locally intruded by metagabbros. unit (ii) is dominated by metadolerites with minor amounts of metagabbros and metabasalts. Where contacts have been observed finer grained rocks intrude coarsed grianed ones. unit (iii) contains metadolerites and meta-pillow-basalt, the latter increasing in abundance stratigraphically upwards, and passing into unit (iv) in which meta-pillow-basalt and meta-pillowbreccia are present in subequal proportions. C. BRYNEIRA GROUP: This group has been redefined to include the following formations: Upukerora Formation: comprising basic volcanogenic conglomerates, sandstones and mudstones. Howden Formation: comprising limestones and basic volcanogenic sandstones and mudstones. Annear Formation: comprising significantly more quartz-rich sandstones and siltstones Tapara Formation: comprising basic volcanogenic sandstones, siltstones and claystones. This formation has been divided into eight informal units based on distinctive lithology. Winton Formation: comprising very thin interbedaed volcanogenic sandstones ru~d mudstones. D. STEPHENS GROUP: This is a new group uniting the Countess and Snowdon Formations. These formations have similar lithologies, mainly massive sandstones, with fewer thin mudstones and thick conglomerates, and indicate a notable change in depositional character from that of the underlying Bryneira Group. A Mid- to Late-Permian age for the sedimentary strata is suggested by the occurrence of Atomodesma trabeculum Waterhouse in the Diston stream sedimentary unit, by A. trechmanni Marwick in the Annear Formation, and a rich late Permian fauna at the top of the Countess Formation. This fauna includes fragments and moulds of brachiopods, corals, bivalves, gastropods, bryozoans, echinoderms and a trilobite. Calcite prisms, regarded as comminuted Atomodesma shells, are present in the Upukerora, Howden, Annear and Snowdon Formations, but more significantly, also in unit (iv) of the Livingstone Subgroup. Their presence strongly suggests a Permian age for the Humboldt Group. The major lithfacies recognised are conglomerate, sandstone, interbedded sandstone and mudstone, with minor amounts of limestone, pebbly sandstone and intraformational conglomerate. The lithofacies are considered to have been deposited in deep water by mass flow and turbidity currents. Modal analyses indicate the sandstones to be mainly lithic volcarenites derived from a basic to intermediate source area. The Annear Formation is exceptional because the sandstones are very significantly enriched in quartz. Bryneira and Stephens Group strata are considered to have been deposited in the axial trough of an elongate basin. Chemical analyses of red and non-red strata indicate that the red colouration varies with Fe2O3 FeO ratio. Red and non-red beds probably reflect variations in the palaeoclimate directly or indirectly attributable to Gondwanan Permian ice-age. Relict igneous minerals and ghost textures in the Red Mountain Ultramafite indicate a mainly harzburgite parent. Microprobe analyses of olivine, orthopyroxene and chromian clinopyroxene give compositions of Fo90 ; En90-92 ; Wo49 En48 Fs3 respectively and also indicate that the original opaque phase was chromian spinel. These values are directly comparable to mineral compositions from ophiolite sequences and Alpine - type ultrabasic complexes. Kizardite, chrysotile and magnetite are the major metamorphic minerals in the Red Mountain Ultramafite. Serpentinisation was probably initiated during an ocean-floor metamorphic episode, further alteration taking place during and possibly after the Rangitata Orogeny. The present mineral assemblage indicates temperatures of formation of less than 300°C and a few kilobars pressure, conditions that are comparable to those producing prehnite - pumpellyite facies assemblages in adjacent strata. Igneous textures are usually well preserved in the Livingstone Subgroup but metamorphic reconstitution is such that only three relict igneous phases now occur. Only Ca-rich pyroxene has been observed and it shows increasing alteration stratigraphically downwards, being most altered in the tectonic inclusions. Microprobe analyses of these clinopyroxenes indicate tholeiitic affinities for these rocks and using the criteria of Nisbet and Pearce (1977) the analyses suggest that the rocks were formed in an ocean-floor environment. Brown hornblende is restricted to the tectonic inclusions and is considered to have crystallised from an evolving magma. Opaque minerals invariably show alteration to sphene and this, together with microprobe data, indicates an original iron - titania oxide phase. Zeolite facies metamorphic assemblages in the southwest of the area pass northeastwards through a narrow zone of lawsonite - albite - quartz facies into an extensive area of prehnite - pumpellyite facies mineral assemblages. This low-grade regional metamorphism is associated with the Mesozoic Rangitata Orogeny. A temperature gradient of about 23C/km was operative during this event. Maximum pressures of approximately 5 kb and temperatures of approximately 380°C were attained. Prehnite - pumpellyite facies mineral assemblages overprint greenschist facies mineral assemblages in the metadolerites, metagabbros and albite amphibolites. Microprobe analyses of amphiboles from these rocks show a compositional gap within and between grains, but a miscibility gap is not developed. Amphibole compositions are governed initially by precursor mineral composition, later being modified by host rock composition. These results suggest that conditions of metamorphic equilibrium have not been attained. The meta-igneous rocks were metamorphosed under ocean-floor conditions of low pressure and of temperatures up to at least 400C, possibly reaching 600C locally. This metamorphic event was of an early Permian age, and was later overprinted during the Rangitata Orogeny. Co-existing phases in the Livingstone Subgroup include pumpellyite(Fe), albite, iron-rich epidote, chlorite, celadonite, prehnite, sphene, quartz and calcite. (Microprobe analyses are given for all but quartz and calcite). Andradite amd intermediate members of the andradite - grossularite series occur with prehnite, epidote, chlorite, quartz, calcite and an opaque phase in vesicle infillings of a non-pillowed metabasalt. Conditions of formation of this mineral assemblage involved temperatures of less than 300°C, possibly even less than 100C and pressue pressures of a few kilobars. Several models are discussed regarding the environment in which the strata at West Dome originated, and the ensuing tectonic conditions that brought about the juxtaposition of these rocks. The simplest model is that of a single Permian - Cretaceous volcanic arc - arc-trench gap - trench in which Humboldt Group (already metamorphosed under ocean-floor conditions) formed the upper plate of the subduction zone and on which Bryneira and Stephens Group strata were deposited in the arc-trench gap; Caples ·· Pelorus terrane rocks probably formed in part of the trench. All of these rocks were folded and regionally metamorphosed during the Mesozoic Rangitata Orogeny. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. West Dome Thesis description Number of pages, maps, CDs, etc. 178 leaves : ill., 3 maps (fold) ; 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 1979Hyden_G Creator An entity primarily responsible for making the resource Hyden, Graham. Date A point or period of time associated with an event in the lifecycle of the resource 1979 Title A name given to the resource Geology of the west dome sector of the Dun mountain ophiolite belt. Subject The topic of the resource Map Igneous petrology Metamorphic geology Sedimentology Paleozoic Atomodesma Dun Mountain Ophiolite ultramafic rocks https://theses.otagogeology.org.nz/files/original/34f3db306455bf51c92343cc00b05f90.pdf 29b212b55dc294eb50137fe2ab5728c6 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 ((167.319926339169086 -46.230938908774903,167.398805834655548 -45.606059936729622,169.382835275988839 -45.700576956785675,169.324976341123374 -46.652507133277147,169.256459797070193 -46.668143028945323,169.089785357096844 -46.67684854491354,168.918165602435352 -46.681561679411423,168.834286746215497 -46.624951237329611,168.787288367027259 -46.562500198257936,168.706075728260004 -46.541614033185127,168.534199032885937 -46.61718214711243,168.418719401432895 -46.634040421075177,168.303327634944111 -46.529326555638015,168.283404307689693 -46.460630430996879,168.177021531029794 -46.37759108063802,168.111448921575033 -46.36051040356714,167.997075396075331 -46.369841192340381,167.870053258651808 -46.403496022869703,167.777500347978531 -46.399295439686227,167.71310216883893 -46.317732541666942,167.645765594995908 -46.26814708107004,167.510894900373501 -46.226006468906412,167.374445943503702 -46.251506514990965,167.303455002844572 -46.240834629324425,167.299809635800045 -46.226361729467889,167.319926339169086 -46.230938908774903)) Author last name Last name of the Author Hyden Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Carter, R.M. Campbell, J.D. Abstract The Abstract for this thesis Mid-Tertiary temperate-water shelf carbonates are extensively developed in Southland and provide excellent examples of Bryozoan-dominated bioclastic sediments which can be matched with smilar bryozoan-dominated assemblages accumulating on the Otago shelf today. Tertiary sedimentation in the Southland Plains and adjacent areas can be attributed to a simple transgressive-regressive episode on which was superimposed local tectonic events and regional palaeo-oceanographic and eustatic sea-level changes. Late Cretaceous-Eocene alluvial, lacustrine and deltaic sediments uncomfortably overlie basement rocks. East of the Oreti River, marginal marine beds grade up into shallow marine mudstones of the Winton Hill Formation (early-mid Oligocene, Lwh-Ld) and highly glauconitic sandy mudstones, algal foraminiferid biomicsparrudites and glauconitic biomicrites (Waimea Member) of the Chatton Formation (late Oligocene; Ld-Lw). At Castle Rock, shallow marine mudstones underly foraminiferid-algal and bryozoan biomicsparites of the Caslte Downs FOrmation (late Oligocene-early Miocene; LD-Po). Laterla facies variations suggest a complex coastal and nearshore physiography; the disposition of coars, basement-derived detritus and algal-rich sediment suggests the presence of locally emergent basement highs. Evidence of very low sedimentation rates, periods of non-deposition, vigourous nearshore erosion is provided by abundant (oolitic) glauconite and limonite, phosphatised (intra)clasts, and a high degree of bioturbation, five omission surfaces occur at the top of the Chatton Formation at Woody Knoll. Coarse, channelised and sheet-like congrolmerates occur locally above the discontinuity (Sharks Tooth Hill Member, Forest Hill Formation) and tectonic instrability may have caused mass failure of coarse detritus. The conglomerates coincide with a change in sedimentary regime - from inner neritic calcareous sandntones, algal-foraminiferid biosparites, or bivalve-cirriped biomicsparrudites (locally formaing a submarine hard ground) to mid-outer neritic bryozoan-dominated facies (Woody Knoll Member, FOrest Hill Formation). The absence of corals and green algae, calcareouse ooids and pallets, and chemically precipitated micrite is consistent with temperate rather than troopical palalatitudes. Bryozoan rudites are the dominant facies within the Forest Hill Formation (late Oligocene-early Miocene; ?Lw··Pl), but fluctuating wind and wave-dominated hydraulic regimes and an irregular sea-floor topography gave rise to a complex mosaic of terrigenous-rich and terrigenous poor bioclastic facies. Twenty-seven traction-emplaced or in situ bioclastic or terrigenous facies and three mass-emplaced facies, plus a number of subfacies, have been recognised. Once a bryozoan-brachiopod and thence bryozoan-dominated assemblage became established through an ecological succession, bryozoans and associated faunas covered considerable areas of the sea-floor during a period of tectonic quiescence. Fragmented bryozoan skeletons, mostly cylindrical branching forms, provided adequate substrate for growth of successive colonies and although in situ colonies were rare, broken colonies have not been transported far from their living site. Nodular, free-living hemispherical and hermit bryozoan colonies are particularly conspicuous. Eocene-Oligocene sedimentation patterns west of the Oreti River contrasted with that exposed in the Forest Hill - Fernhill district and at Castle Rock. Rapidly subsiding flysch basins developed in the Waiau and Te Anau areas, coinciding with inception of the Alpine Fault oblique continental plate boundary. Smaller N-NNE trending fault-controlled basins were also established, and rapidly filled, east of the Longwoods (Oreti-Aparima basin) and east of the Takitimu Mountains (Braxton basin). The sequence at Clifden and in the Alton Burn records sedimentation on the margin of the Waiau flysch basin. Basal (Eocene) non-marine and marginal marine carbonaceous mudstones and sandstones with thin lignite horizons are overlain by richly microfossiliferous early-mid Oligocene (Lwh-Ld) deep--water mudstones. These sediments, probably deposited on the basinal slope, correspond to the period of maximum transgression further east; they grade up into late Oligocene sandy mudstones and bryozoan-molluscan-foraminiferid biosparites (Te Karara Formation). Emplacement of thick conglomerates (Sharks Tooth Hill Member) heralded an abrupt change in sedimentary regime - from off shore mudstcnes to shallower, neritic bryozoan rudites (Woody Knoll Member). The apparently younger age of the Forest Hill Formation at Clifden (Po-Pl) compared to that at Forest Hill (?Lw-Pl) is consistent with westward progradation of the carbonate shelf across the now-filled Oreti-Aparima basin and the partially, if not totally submerged Longwoods basement high. Neritic channels provided a conduit for transporting bioclastic sediments into the still subsiding Waiau basin. A gradual increase in terrigenous detritus towards the top of the Forest Hill Formation reflects gradual shoaling. At Forest Hill, the limestones are overlain by inner neritic sandy mudstones and carbonaceous facies, and the regressive sequence mirrors that of the transgression. At Clifden, the limestones are overlain by neritic sandstones (mid-Miocene). Sedimentation rates of the order of 1-2 cm/1000 years are considered likely for the Forest Hill Formation. Such low rates of deposition in a temperate water envirorunent periodically gave rise to CaCO3 undersaturation. Consequent sea-floor dissolution of aragonitic and some high-Mg calcite skeletons was arrested only by early lithification in micritic sediments, or by low permeability (e.g. in terrigenous mud-rich sediments). The observed diagenetic sequence within ·the Forest Hill and Castle Downs formations can be explained by restricted submarine cementation, or close to the sediment-water interface (soft sediment to a depth of several cms was widespread). With shallow burial (tens of metres), ferroan calcites were widely precipitated (phreatic zone). Evidence of subsequent uplift east of the Longwoods is provided by vadose goethite cements which postdate early ferroan calcite rim cements and predate mesogenetic, pore--filling ferroan sparrites. At Castle Rock, the position of a fossil water table can be delineated on the basis of goethite distribution. A more complex diagenetic sequence occurs in facies associated with a submarine hardground at Forest Hill.. Six distinct cement generations are recognised, including ferromanganese and haematite/goethite phases. Oligocene-Miocene limestone turbidites of the Waiau and Braxton basins are of comparable lithology to the bioclastic limestones of the Forest Hill and Castle Downs formations, but the turbidites possess quite different diagenetic histories which reflect their different depositional and diagenetic environments. The role of compaction is probably the single most important factor in diagenesis of the limestones. Coarse calcarenite to calcirudite grade bioclastic sediments have been sufficiently compacted to reduce high initial porosities to less than 10%. Dissolution of aragonitic skeletons, interpenetrative grain contacts, and selective intergranular solution of bioclasts within terrigenous clay-rich horizons, provided sufficient carbonate solutions to further reduce this porosity to less than 2%. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Southland Thesis description Number of pages, maps, CDs, etc. 487 p., 44 leaves of plates : 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 1979Hyden_FM Creator An entity primarily responsible for making the resource Hyden, Fiona Mary. Date A point or period of time associated with an event in the lifecycle of the resource 1979 Title A name given to the resource Mid-tertiary temperate shelf bioclastic limestones, Southland, New Zealand. Subject The topic of the resource Mineralogy Paleontology Sedimentology Cenozoic brachiopods bryozoa glauconite limonite paleoecology