1 10 4 https://theses.otagogeology.org.nz/files/original/7672ce430b39c6b99de82ae112a7a4f8.pdf ac5f73578c5ff7f9e3d88828a86d14c7 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 ((170.2406113602338 -45.752754865914653,170.286167593748729 -45.753370537614913,170.285230837798963 -45.786689425434872,170.239670984917382 -45.785597026416852,170.2406113602338 -45.752754865914653)) Author last name Last name of the Author Bowie Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PGDipSci Advisers Who supervised/advised this student Gorman, A.R. Lee, D.E. Abstract The Abstract for this thesis In 2007, airborne geophysical surveys identified four sub-circular features presenting high magnetic intensity near Hindon, 25 km NW of Dunedin, within the Miocene Waipiata Volcanic Field (WVF). Similar magnetic anomalies within the WVF are associated with maar-diatreme structures, e.g., Foulden Maar or Gladsmuir diatreme. Subsequent excavations produced evidence that at least two of the basins contain extremely fossiliferous laminated diatomite and/or carbonaceous mudstone, deposited in former maar-lakes. Surface exposure is very limited, which means that geophysical surveys (ground-based magnetic, microgravity and seismic) are essential for accurately representing the size, depth and sediment infill. The large magnetic susceptibility of the basaltic diatreme allows for ground-based magnetic surveys to accurately characterise the size and extent of all four structures. It was found that these structures extend over an area of 16 km2 and are individual anomalies probably related to the same magma source. The relative density of rock within the maar complex then allowed for microgravity surveys to be conducted. Schist typically has a density of 2.73, basalt 2.77, volcanic breccia 2.19 and diatomite 1.53 g/cm3. The relatively low density of diatomite in the subsurface produces a negative anomaly that has been characterised by a Worden Gravimeter survey. Two maars have yielded negative anomalies related to a thickness of diatomite in the subsurface. The final geophysical method was a seismic survey conducted in Maar One. The seismic plot has revealed the thickness and lithologies of the sediment infill within Maar One. This has clarified that at least one of these deposits is a suitable candidate for full coring and paleoenvironmental studies, as at Foulden Maar some 25 km to the northwest. An integrated geophysical interpretation of Maar One has indicated that 160 to 190 m of laminated sediment is present within Maar One. Seismic and microgravity surveys have allowed for selection of an appropriate location to recover this maximum thickness. These two methods provide a generally consistent interpretation of basin thickness (although the thickest locations lie 150 m apart in the two models. A site between these points is most suitable for a drill core to be located. The Foulden core yielded 127 m of diatomite, enabling the reconstruction of a 100,000- year-long terrestrial record of climate, fossil biodiversity and ecosystems. A potential 190 m core of diatomite at Hindon suggests this record could be extended and improved. New samples of volcanic rock have been selected for radiometric dating to confirm the early Miocene age established by preliminary palynological biostratigraphy. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Hindon Maar Hindon East Otago Thesis description Number of pages, maps, CDs, etc. xvi,149 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 2015Bowie Creator An entity primarily responsible for making the resource Bowie, Elliot 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 Geophysical Characterisation of the Hindon Maar Complex Subject The topic of the resource Geophysics geophysics Hindon Maar maar https://theses.otagogeology.org.nz/files/original/99ab62d8ee34015ad8b1d54afd669882.pdf b4b0a97198b1b23dd34f27acf0db853a 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 ((-110.538039144707525 35.604813712081047,-110.324127389853018 35.663024395560669,-110.070998479941906 35.668843111302046,-109.839260745516228 35.494095647681959,-109.871347508744364 35.31896388243829,-110.174389161454911 35.084858422440377,-110.359779348995446 35.102439939710258,-110.57725629976413 35.359862293443044,-110.538039144707525 35.604813712081047)) Author last name Last name of the Author Lefebvre Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student White, J.D.L. Kjarsgaard, B. Abstract The Abstract for this thesis Maar-diatreme volcanoes are unique in that most "eruptive" activity takes place below the ground surface, thus forming large conduit structures filled with pyroclastic deposits that are large relative to their volcanic edifices. These small-volume volcanoes are traditionally divided into three main levels based on common divergences in geometry and internal architecture at different depths: feeder dike, diatreme structure (conduit structure) and tephra ring (surface deposits). Although maar-diatreme volcanoes worldwide show generally very similar characteristics despite many different magma compositions, there is no consensus on how these volcanoes excavate the country rock and develop during an eruption. This study aims to determine the processes and relative timing of activity taking place below the ground surface by combining detailed mapping of three exemplary exposures of diatremes at different structure levels, from dike-widening transition to well-formed diatreme, within the Hopi Buttes volcanic field. Observations from different volcanoes are readily related to one another because the field had homogeneous preeruption hydrology, wall-rock stratigraphy, and magma composition, with a narrow range of eruption ages. Castle Butte Trading Post (CBTP) comprises four closely spaced narrow spatter-dikes and wider maar-diatremes ~150 m below the pre-eruptive surface. The spatter-dikes consist of bedded, variably welded deposits plus wall-rock debris in multiple NEyounging sequences demarcated by truncation surfaces. They reveal a shallow plumbing cycle of pulsating, weak, hot spatter fragmentation, concurrent wall-rock failure and periodic slips that truncated down dropped bedded deposits from repeated magma withdrawal and diversions during progressive NE fissure extension and vent stepping. Both Standing Rocks West (SRW) and East (SRE) diatremes, exposed ~300 m below the pre-eruptive surface, are part of a single larger volcanic complex formed along a series of irregularly offset NW-SE trending dikes. SRW comprises dominantly multiple, structureless irregular columns of well-mixed, poorly sorted juvenile-rich lapilli tuff deposits that contain abundant recycled material; they truncate local marginal layered deposits and peripheral country rock breccia. SRW mostly records late-stage activity of multiple, small-volume, explosions and jets within loose pyroclastic debris, which resulted in gradual mixing, recycling and remobilization of cognate diatreme debris, incremental addition of juvenile material and a well-formed diatreme. In contrast, SRE comprises predominantly country rock lithic-rich breccia of coarse inhomogeneously mixed wall-rock blocks, cross-cut by domains of lapilli tuff deposits that are overlain by spatter deposits and cross-cut by irregularly distributed dikes. SRE shows a progressive transition from fissure to diatreme, but an overall evolution from explosive to weak eruption styles, thus reflecting an arrested diatreme. Instead of simply representing vertical differences of a diatreme structure, CBTP, SRE and SRW reveal much volcano-to-volcano variation, and even within-eruption variation in eruption processes and intensity. Variability in eruption intensity is inferred at all scales i.e. between different en echelon dike systems, between the structures formed along segments within these systems and between the vents for individual volcanoes at the surface. These Hopi Buttes volcanoes show that the roots of weakly and strongly explosive small volcanoes are shared with changes in explosive intensity over short distances and not necessarily systematic variations in behaviour through time. The evolution of the shallow plumbing during an eruption involves local feedback effects that critically affect eruption style over short times and distances. Neither magma composition nor country-rock hydrology can be considered as the primary control on inter-eruption variation or on changes through a single eruption in the Hopi Buttes volcanic field. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/4268">http://hdl.handle.net/10523/4268</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. Hopi Buttes volcanic field Navajo Nation Arizona USA. Thesis description Number of pages, maps, CDs, etc. x, 279 leaves plus papers. Maps in colour 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 2013Lefebvre Creator An entity primarily responsible for making the resource Lefebvre, Nathalie Date A point or period of time associated with an event in the lifecycle of the resource 2013 Title A name given to the resource Volcanology of maar-diatreme volcanic vent complexes, Hopi Buttes Volcanic Field, Navajo Nation, Arizona, USA Subject The topic of the resource Volcanology diatreme fissure Hopi Buttes maar monogenetic root zone shallow plumbing volcanism https://theses.otagogeology.org.nz/files/original/db8f0802f3d5f71185c426200dd501a1.pdf 1c947017f58671c90aa4b78f0fbbe979 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 ((170.187137494384501 -45.510032427669636,170.200030816787518 -45.506181643648311,170.210429485329627 -45.501375358354139,170.219528718734324 -45.497131876199923,170.256736333604664 -45.498032182761428,170.252450519762476 -45.542583979714777,170.186017827729188 -45.540965555793733,170.187137494384501 -45.510032427669636)) Author last name Last name of the Author Kaulfuss Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Lee, D.E. Wilson, G.S. Gorman, A.R. Abstract The Abstract for this thesis Foulden Maar is a latest Oligocene-earliest Miocene maar-diatreme volcano located in a vent cluster of the monogenetic Waipiata Volcanic Field in Otago, New Zealand. The present–day erosion level exposes a 1000 x 650 m wide maar crater that is filled by fossiliferous diatomite. At nearby Gladsmuir, stratified phreatomagmatic pyroclastic tuff, lapilli tuff and breccia of the upper diatreme zone of a second maar–diatreme volcano are capped and transected by coherent basanite that indicates late–eruptive magmatic explosive and effusive activity. Other volcanic remnants in the vicinity represent eroded lava plugs and lava flow units of similar age but without genetic relation to Foulden Maar. The pre–eruptive stratigraphy above the schist basement is largely eroded in the area but a sedimentary sequence consisting of unconsolidated late Eocene–Oligocene glauconitic sands and fluvial–palustrine sediments of presumably late Oligocene–early Miocene age (Dunstan Formation) can be reconstructed from local erosion remnants and accidental lithic clasts in maar tephra at Gladsmuir and reworked maar tephra at Foulden Maar. At Foulden Maar, a ~188 m thick crater–infilling sequence was investigated in surface pits and two drilling cores. Four distinct lithozones (LZ 1–4) were recognized, each including a characteristic assemblage of lithofacies types that reflect the post–eruptive sedimentation history of the maar crater and the environmental factors that operated during the crater–infilling period. A massive breccia rich in country rock fragments in an ash and mud matrix in the basal LZ 1 was deposited by a voluminous, cohesive mass–flow in the central part of the immediate post–eruptive crater, when the crater walls and the inner slopes of the tephra rim were steep and unstable. A 62 m thick sequence of massive or graded, coarse to fine–clastic lithofacies types in lithozone 2 represents subaqueously emplaced debris flow and turbidity current deposits. The existence of a maar lake at this depositional stage is evidenced by textural features of lithofacies types in LZ 2 and by limnic microfossils such as sponge spicules and algal remains. Mainly dense and blocky, vitric ash and lapilli–sized clasts that are present in LZ 2 are reworked juvenile clasts of the tephra rim and exhibit textural features that are in agreement with a phreatomagmatic explosive eruption style at Foulden Maar. Quartz sand grains and glauconite, mud– and sandstone clasts and lignite fragments found in mass–flow horizons in LZ 2 represent accidental lithic clasts of the tephra rim and support inferences about the pre–eruptive stratigraphy from field mapping. Facies types in lithozone 3, at 115.18–101.55 m in core FM 2, include massive and stratified clastic mass–flow deposits with smaller grain–size and bed thickness than in LZ 2. They reflect sedimentation mainly from turbidity currents and minor cohesive debris flows from proximal slopes of the maar lake basin. Deep, meromictic conditions and seasonally increased bioproductivity within the maar lake are evidenced by thin intervals of laminated diatomite in LZ 3. Lithozone 4 consists of 106 m of laminated and non–laminated diatomite that indicates a biogenic fall–out sedimentation mainly controlled by bioproductivity of diatoms and sponges, and sporadic mass–flow events within the maar lake basin. The preserved lamination, the presence of organic matter, articulated fish and insects, and the absence of bioturbation confirm a calm and anoxic sedimentary environment at the lake bottom. The constant composition and thickness of lamination throughout LZ 4 reflects stable environmental conditions over a period of ~127,000 years, during which time mass–flow events decreased in frequency due to infilling of the lake basin. At this depositional period, the lake was surrounded by a subtropical evergreen forest. The lack of fluvial and eolian sediments in the studied sequence indicates a small catchment area for the crater sedimentation and a hydrologically closed system for the maar lake. Four tephra beds present in LZ 3 and 4 indicate nearby strombolian eruptions contemporaneous with maar lake sedimentation. In addition to previous paleontological studies that were mainly focussed on plant fossils, numerous new arthropods, fish, and trace fossils discovered and described in this study provide valuable new insights into the paleoecosystem at Foulden Maar and a novel perspective on the terrestrial biodiversity of Zealandia about 23 million years ago. Arthropods were a key component of the forest ecosystem at the maar lake, including representatives of the Coleoptera, Hymenoptera, Isoptera, Hemiptera, Diptera, possibly Blattodea, Araneae and Acari. Among 13 confirmed insect families, the curculionid beetles (weevils) and Formicidae (ants) are most diverse. The majority of insects are ground–dwelling, forest litter and wood–living taxa with low dispersal ability. Flying and aquatic insects are rare. Arthropod–plant interactions on plant fossils include external foliage feeding, galling, leaf mining, piercing–and–sucking and seed predation as well as foliar domatia and flowers with insect pollination syndrome, which indicates a well established terrestrial ecosystem in Zealandia at the Oligocene–Miocene boundary. The taxonomic composition of the arthropod taphocoenosis is in agreement with a warm temperate to subtropical paleoclimate. Collectively, these fossils represent the first pre–Quaternary terrestrial arthropod fauna from New Zealand. The first evidence of larval stages of Galaxias effusus Lee, McDowall & Lindqvist 2007 supports previous suggestions that this fish species was non–migratory and locked to the maar lake. The predominance of juvenile stages of this species is likely related to seasonal diatom blooms. Anguilla sp. described in this study represents the first non–European fossil of freshwater eels. It contradicts previous suggestions of an absence of Anguilla from Miocene New Zealand and challenges the timing of radiation of freshwater eels determined from molecular phylogeny. Three morphotypes of coprolites can be linked to ontogenetic stages of Galaxias effusus and Anguilla sp. but most of the morphologically and compositionally diverse coprolite types found in this study represent vertebrate taxa that are currently not known from body fossils. Together, the fossil plants and animals from Foulden Maar provide a unique window into a mid-latitude, low elevation southern New Zealand terrestrial ecosystem. Some of the plants and animals have close living representatives in the modern New Zealand biota, but many taxa are now extinct in New Zealand. This is the first detailed account of a pre-Quaternary maar deposit in the Southern Hemisphere. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/3838">http://hdl.handle.net/10523/3838</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. Foulden Maar central Otago. Thesis description Number of pages, maps, CDs, etc. iv, 322, [38] pages : illustrations (some colour), maps (some colour), ; 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 2013Kaulfuss Creator An entity primarily responsible for making the resource Kaulfuss, Uwe Date A point or period of time associated with an event in the lifecycle of the resource 2013 Title A name given to the resource Geology and Paleontology of Foulden Maar, Otago, New Zealand Subject The topic of the resource Paleontology Late Oligocene Early Miocene Waipiata volcanics Anguilla diatreme Field fossil Foulden insects lake maar Miocene New Zealand pyroclastic Sediment volcanic Waipiata https://theses.otagogeology.org.nz/files/original/75b5f961d259e77ab56d70cfa3fb8830.pdf 0807399922b65521b24443691f74fdcb Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format MULTIPOLYGON (((170.609321054418956 -45.455228026503654,170.611023917892567 -45.452763714561065,170.716139093469394 -45.531125784359006,170.609321054418956 -45.455228026503654)),((170.321698845852012 -45.867905864741019,170.169807260542541 -46.14620484708496,169.747845574527219 -46.19021751020783,169.904071956453322 -45.874492024406827,169.881739752211161 -44.930247273080035,170.609321054418956 -45.455228026503654,170.321698845852012 -45.867905864741019))) Author last name Last name of the Author Németh Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student White, J.D.L. Reay, A. Abstract The Abstract for this thesis The Miocene Waipiata Volcanic Field (WVF), New Zealand, is an eroded phreatomagmatic volcanic field. Three different types of vent or vent complex were recognized. Vent-filling deposits comprising predominantly lava, preserved in the form of plugs, necks, lava lake remnants, lava flows, or dykes, were classified as Type 1 vents. Type 1 vents are inferred to be the remnants of scoria cones, most of them with thin basal phreatomagmatic pyroclastic deposits. Vents represented by predominantly pyroclastic infill are classified as Type 2 vents. Type 2 vents are inferred to have been the substructures of phreatomagmatic tuff ring/maar volcanoes, many of which may have had associated scoria cones. Type 3 vent complexes are groups of closely spaced or overlapping vents, with voluminous preserved lava flows. Type 3 vent complexes are the remnants nested maars and tuff rings with associated magmatic explosive and effusive products. Pyroclastic rocks of most of the Waipiata vents record initial phreatomagmatic explosive activity fuelled by groundwater followed by Strombolian-style eruptions. Erosion rates for the WVF are 5 to 50 m per million years. Cenozoic sedimentary cover was widespread and still complete ( e.g. 200 – 400 m thick Oligocene marine units) at the time of volcanism, although over much of the field no Cenozoic sedimentary rock units remain today . Vent alignments largely follow the basement structural pattern of the Otago Schist, defining NESW and NW-SE trends. The longest vent alignment, traceable in ~ 30 km, coincides with and is parallel to the largest fault zone in the Otago region, the NW-SE trending Waihemo- fault zone. The total volume of magma erupted in the WVF is estimated to have been ~ 9 to 40 km^3 DRE. A systematic compositional sequence exists at each volcano, with initial phreatomagmatic eruptive products being differentiated tephrite and phonotephrite composition, whereas subsequent lava flows and dykes are of primarily basanite. Basanite was parental to the tephrite and phonotephrite. Basanite generated beneath WVF appears to have “failed” to reach the surface, instead being captured en route and stored to produce tephrite phonotephrite via 15-25 % crystal fractionation of olivine and clinopyroxene. Many attempted eruptions of parental basanite "failed", and that each successful eruption at the surface involved both a newly-injected basanite from depth, and a transected and entrained remnant of melt evolved from magma captured at shallower depths from a preceding "failed" eruption. Significant amount of magma was underplated beneath or injected into the crust of the WVF. The Otago crust is density and rheologically stratified, and in the Miocene lay within a mild extensional (strike- slip) tectonic regime; this combination was responsible for the entrapment of magma at various levels in the Waipiata – Dunedin region. The WVF-wide trend in magma evolution at individual vents has also been demonstrated from the mild extension-related Late Miocene Bakony- Balaton Highland Volcanic Field (BBHVF), Hungary. Recognition of this pattern at two unrelated fields may suggest that initial injection, with subsequent entrainment to produce dual-source monogenetic eruptions may be common in intracontinental alkaline basaltic volcanic fields. It is suggested that the lithospheric density and rheological structure, together with the state of stress, play an important role in fostering magma injection and entrapment in areas where the crust is 1) strongly density stratified, 2) relatively thin, 3) hot (high heat flow), and 4) the crustal stress regime mildly extensional, preferably with strike slip movements. These conditions were shared by the WVF and the BBHVF, with the result that magmas, processes of storage and differentiation, and ultimate eruption and volcano formation were in many ways remarkably similar. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Waipiata Otago north Thesis description Number of pages, maps, CDs, etc. 2 v. : ill. (some col.), maps (1 folded, col.) ; 30 cm. + 1 computer disk. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2001Nemeth Creator An entity primarily responsible for making the resource Németh, Károly, 1969- Date A point or period of time associated with an event in the lifecycle of the resource 2001 Title A name given to the resource Phreatomagmatic volcanism at the Waipiata volcanic field, Otago, New Zealand Subject The topic of the resource Volcanology Igneous geology Structural geology Map basanite erosion Hungary maar New Zealand phreatomagmatic scoria tephrite vent