1 10 2 https://theses.otagogeology.org.nz/files/original/5e7099bd4d2a0d7c0302f4c780d082bc.pdf 00d8c01817a9e57dc9c3d2d73b1871bb 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 ((159.611042297072686 -76.747334877898581,159.59952317493844 -76.747155749513155,159.60364731091903 -76.734579204102531,159.603661093366412 -76.734537135035197,159.603904830747211 -76.733793115918758,159.607394514329997 -76.723131658338772,159.609728851011255 -76.715990491823646,159.61016919719259 -76.714642541076586,159.669508573285327 -76.715454613706413,159.708653558025588 -76.715982703436609,159.769040595726864 -76.716785488101934,159.767177065568944 -76.725839214640857,159.765644925912881 -76.733273801862936,159.762266606988646 -76.749637883736639,159.757407528486851 -76.749565288902389,159.665259214356865 -76.748170937708153,159.611042297072686 -76.747334877898581)) Author last name Last name of the Author Hood Hills Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student White, J.D.L. Abstract The Abstract for this thesis Jurassic fragmentation of Gondwanaland initiated the widespread voluminous outpouring of tholeiitic magma that is recorded on four continents. In Antarctica the Ferrar Supergroup, which outcrops along the length of the Transantarctic Mountains, formed within a wet failed rift during this break-up. It includes the extensive Ferrar Dolerite sills and dykes, and the extrusive Kirkpatrick flood basalt, and explosive volcanic deposits of the Mawson Formation. The Allan Hills, in southern Victoria Land, provides excellent exposure of these volcaniclastic deposits and was the site of study for this project. A small area was mapped in detail to determine the mode of origin of a part of the Mawson Formation and its relationship to the recently described 'phreatocauldron' in the nearby Coombs Hills. The Mawson Formation in the Allan Hills has previously been interpreted as part of a regional lahar field that formed as a precursor to Kirkpatrick flood-basalt eruption. Structural relationships and componentry of the Mawson Formation in the area, supplemented with results of coal vitrinite analysis, are difficult to reconcile with a laharic origin. During field work three different lithofacies were defined; a) thick, structureless, lithic-rich ponded pyroclastic density current deposits, b) several block-rich explosion or lag breccia horizons, and; c) a diatreme-like breccia-filled conduit (Ninnis Neck), one of the sources of other Mawson Formation deposits. These deposits are here interpreted to have formed within a phreatomagmatic vent complex, created by the coalescence of multiple vents similar to and including Ninnis Neck. Phreatomagmatic activity was fuelled by Fuel-Coolant-Interaction (FCI) as Ferrar Supergroup magmas intercepted water-saturated sedimentary materials of the Beacon Supergroup. Abundant peperite fragments formed by incomplete FCI, involving mingling of Beacon Supergroup clastic debris with magma preceding explosive fragmentation. Peperitic margins on basaltic dykes provide further evidence for involvement of wet sedimentary debris. Ninnis Neck was formed by upwards-directed tephra jets late in the overall complex's history. Recycling of tephra within individual vents, such as Ninnis Neck, was important in slowing the 'drying out' process and lengthening explosive activity. Growth of the Allan Hills vent complex occurred by lateral expansion facilitated by repeated failure of Beacon Supergroup strata along the margins due to volcanic and/or tectonic activity. The vent complex is interpreted to be relatively shallow, indicated by the limited sampling depth of accidental lithic clasts. The style of volcanism expressed in the Allan Hills of a shallow, possibly broad phreatomagmatic vent complex is comparable to that of the nearby Coombs Hills, and appears to have been widespread through much of the area covered by Kirkpatrick la vas now exposed in the Transantarctic Mountains. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Victoria Land south Antarctica Allan Hills Antarctica Thesis description Number of pages, maps, CDs, etc. viii, 107, [22] leaves : col. ill., col. 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 2004Hood_Hills Creator An entity primarily responsible for making the resource Hood Hills, Simone Belinda. Date A point or period of time associated with an event in the lifecycle of the resource 2004 Title A name given to the resource Wright dykes : a geochemical study of the dyke-forming rock types of the Wright Valley, Southern Victoria Land, Antarctica Subject The topic of the resource Volcanology Igneous geology Structural geology mafic volcaniclastics magma Mawson Formation phreatomagmatic volcanic complex https://theses.otagogeology.org.nz/files/original/bbeb8ce993feccc415610f7dda148bf1.pdf 31af8ac74fedc763b3785cb8e92e9780 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author McClintock Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? MSc Advisers Who supervised/advised this student White, J.D.L. Abstract The Abstract for this thesis The Mawson Formation at Coombs Hills, Antarctica comprises mainly massive tuffbreccia (~80% vol.), includes a high proportion of accidentallithics, has steep contacts with country rock, includes rafts of bedded pyroclastic rock and country rock, and is intruded by and intermingled with dikes, sills and peperite. Massive tuffbreccia deposits are cut by steeply dipping to sub-vertical zones oftuffbreccia of contrasting componentry and grainsize to host rocks, tangled with irregular intrusions and peperite. Dikes or pods of coherent basalt metres in diameter grade, via peperite contacts, into rafts of undisrupted country rock, and into surrounding tephra comprising sedimentary debris mixed with glassy basaltic clasts. The Mawson succession is capped by planar and cross-bedded tuff, lapilli tuff and tuff breccia, which comprises ::::;1 0% of the Mawson overall. Componentry suggests quarrying of country rock from relatively shallow levels (?::::;700 m). Coombs Hills outcrop records non-explosive to explosive magma-water interaction and intrusion of associated hypabyssal complexes within a novel type of phreatomagmatic vent complex that is basaltic, large volume (kilometres3 to tens ofkilometres3 ) and oflow to negative relief. This unusual style of volcanism developed as the precursor to Ferrar LIP magmatism during Middle Jurassic fragmentation of Gondwana, when voluminous rising flood basalts intercepted equally abundant water-saturated Beacon Supergroup sediments and sedimentary rocks. Similar rocks elsewhere in the Transantarctic Mountains, and associated with other flood basalt provinces worldwide (Karoo LIP, Siberian Traps), suggest that this style of basaltic volcanism may be characteristic of environments of combined rifling and flood magmatism. Although Coombs Hills is an atypical vent complex, processes of transport and deposition within the complex were like those in other subaerial phreatomagmatic volcanoes. The bulk of deposits at Coombs Hills are most like those of lower diatremes and diatreme root zones, recording tephra jetting and churning of massive vent-filling tephra by phreatomagmatic explosions. Water-magma interaction was driven by interaction of basalt with water hosted in porous country rock and vent-filling debris. Spatial and temporal heterogeneity in availability of external water led to a variety of eruptive styles at many sites both laterally and vertically within the Coombs Hills crater. Some tephra was deposited by base surge and pyroclastic flow beyond active eruption sites, but broadening of craters via lateral quarrying recycled most of this volcaniclastic rock en masse back into the vent. Quarrying was facilitated by unstable country rock collapsing from vent margins, leading to digestion of collapsed blocks into massive vent fill and adding both mass and further external water to the volcanic system. The fundamental controls oflarge-volume phreatomagmatism at Coombs Hills were: (1) An abundant magma supply associated with emplacement and eruption ofFerrar LIP flood basalts; (2) An equally abundant shallow-level external water hosted in poorly consolidated, porous and permeable Beacon Supergroup country rock, with water supply enhanced by moderate rainfall in a humid climate; and (3) Poorly consolidated, fragile wall rock, which facilitated repeated collapse of vent margins into vents to create a broad shallow vent complex most like a nest of diatremes. Wall rock collapse and subsequent crater growth increased the supply of water-saturated sediment available to fuel eruptions, increased the potential capture of local drainage and reduced the escape of water-saturated tephra from craters, allowing recycling of water as well as pyroclasts. Implications for volcanic processes are ( 1) that recycling of water is probably as ubiquitous as recycling of pyroclasts in phreatomagmatic vents, and allows largevolume phreatomagmatic systems to grow beyond constraints imposed by far-field recharge of external water alone; (2) that the proportion of recycled water increases with vent size; and (3) that peperite is an important indicator of, and participant in, phreatomagmatic explosions, and magma-sediment interaction can promote enhanced explosivity of magma-water interaction. Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Coombs Hills Antarctica Antarctica Thesis description Number of pages, maps, CDs, etc. 1 v. (various pagings) : col. ill. (3 folded) ; 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 2001McClintock Creator An entity primarily responsible for making the resource McClintock, M. K. (Murray Kevin) 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 Phreatomagmatism at Coombs Hills, Antarctica : magma-water super-volcanism in a wet, failed rift Subject The topic of the resource Volcanology magma phreatomagmatism