School of Earth Sciences - Theses
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ItemEnvironmental fate and transport of TNT in soil at the former explosives factory Maribyrnong( 2002)Highly toxic explosives compounds can potentially contaminate soil and groundwater and pose extended environmental hazard due to their persistence. Explosives contamination within soils was investigated at the former Explosives Factory at Maribyrnong (EFM), by sampling and spectrophotometric / HPLC analysis. The environmental fate and transport of 2,4,6-trinitrotoluene (TNT) was assessed via batch and microcosm testing to quantify the influence of key subsurface sinks, adsorption, and transformation, and hence evaluate natural attenuation as a remediation option. A five tonne crystalline TNT source zone was delineated within soils at the base of a TNT process waste lagoon. This source was found to be supplying aqueous TNT loading to subsurface soils and groundwater, with the resultant plume localised to the shallow clay sequence due to a combination of natural attenuation processes and hydrogeological constraints. Freundlich described sorptive partitioning was found to be the main TNT sink at EFM (KF= 29 mL/g), while transformation rates were moderate (3.86 x 10-4 hr-1) due to aerobic conditions, and TNT toxicity inhibiting microbial degradation. Slow groundwater migration toward the Maribyrnong River (0.7 m/yr) and upward hydraulic gradients within underlying sand and gravel aquifers serve to increase TNT residence time within the clay aquitard, leading to increased interaction with adsorptive substrates and microbes and/or elements of the soil matrix responsible for aerobic transformation. Remediation of the contaminated lagoon may involve removal and treatment/landfilling of the top 1m of soil, then refilling with an impermeable capping allowing ongoing natural attenuation of residual TNT at depth via anaerobic degradation and sorption.
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ItemThe origin of the South Australian Heat Flow Anomaly( 2007)The South Australian Heat Flow Anomaly is a zone of high surface heat flow (averaging 92 ± 10 mW m-2); one of several central Australian Proterozoic terranes rich in heat producing elements (HPEs). Its bulk crustal average heat production is between two and three times the global average, indicating an enormous regional enrichment of uranium, thorium and potassium. Until now the distribution of HPEs in the crust has been calculated based on surface heat production; here, a method that uses the temperature at the Moho (as calculated by seismic inversion models) is introduced and found to have good agreement with models that assume a single enriched layer in the upper crust. This layer is found to be between 15-20km. The onset of recycling of uranium through the crust and mantle at the end of the Archaean has been proposed to have produced a peak in uranium available to crust-building, at least partially contributing to the creation of a long-lived geochemical anomaly in Central Australia. However analysis of lead isotopes of K-feldspars from the SAHFA indicates that at the time that crust was first extracted from the mantle, thorium was enriched relative to uranium (not vice versa). In order to investigate more recent effects of such high heat flow, the Tertiary cooling history of the Mt. Painter Inlier is investigated using (U-Th-Sm)/He thermochronology, which has a closure temperature of ~70°C. The most recent ages recorded are ~38 ± 5 Ma, and are argued to record burial of 1400 ± 200m under basement and Cretaceous sediment.
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ItemAustralian Neoproterozoic glaciation: a study of the Sturtian glacial deposits in the Arkaroola region, Northern Flinders Ranges South Australia( 2005)The late Proterozoic Sturtian glacigenic succession exposed in the Arkaroola region of the Northern Flinders Ranges record the earliest of two global Neoproterozoic `Snowball' glacial events in the Adelaide Geosyncline, South Australia. Two stratigraphically disparate glacigenic units were recognised in the late Sturtian succession in the Arkaroola region, a subaerially deposited glacial till - the Merinjina Tillite, and an unclassified glaciomarine diamict unit. The Merinjina Tillite unit preserves a five-fold lithostratigraphy, hosting englacial melt-out deposits, glaciolacustrinal sediments and dominated by a massive to poorly-bedded tillite unit deposited directly from glacier ice. The glaciomarine diamictite preserves down-slope mass-flow deposits, as well as turbidite sequences, slumping and sediments from glacial fall-out including dropstones embedded in laminated muddy-shale and is interpreted as a basin-margin marine deposit. Palaeocurrent analyses across the Northern Flinders Ranges and stratigraphic reviews of analogous Sturtian glacigenic deposits elsewhere in the Northern Flinders Zone suggest palaeotidal influence from the north-north-west and indicate a north-north-west-sloping basin margin in the Northern Flinders Zone. Two major palaeoclimatic phases were recognised in glacigenic rocks the Arkaroola region. A glacial advance phase is represented by the advance of continental glacial sediments, across a topographically-elevated, subaerial surface and extending down-slope into a submarine basin. The other, represented regionally by dropstone shales, is interpreted as glacial retreat and the termination of Sturtian `Snowball Earth' conditions. A rise in palaeo-atmospheric temperatures is inferred, causing melting of continental and marine ice-sheets and resulting in a regionally-extensive marine transgression. The slight increase in water temperature during glacial retreat is believed to have triggered carbonate precipitation and the ultimate deposition of cap dolomites which overly the glacigenic sediments across the Adelaide Geosyncline.
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ItemDetrital zircon geochronology of Neoproterozoic glacials, flinders ranges, South Australia( 2009)A geochronological survey of Neoproterozoic glacial sediments in the Flinders Ranges, South Australia has traced possible source rocks and potential transport directions. A distinct change in the dominant detrital zircon populations present in the earlier Sturtian glacials and the later Marinoan glacials is clearly evident. The major zircon populations present in each of the Sturtian-age samples lie within 1500 -1800Ma, while the majority of Marinoan samples lie between 1100-1400Ma. Potential source rocks for the 1500-1800Ma population include the Gawler and Cumamona Cratons, which are local to the study area. The 1100-1400Ma. population can be traced further north to the Musgrave Inlier in addition to the Albany-Fraser belt and Pinjarra Orogen , north west of the sample localities. The change in zircon population could therefore be accounted for by a change in glacial transport direction during the respective epochs. This may indicate a difference in the severity of the glaciations. An alternative explanation for the difference in detrital zircon signatures could be a change in source rock erosion during each glacial period. Uplift of the Musgrave Inlier or similar basement terrains between the glaciations would provide younger zircons for deposition within the Marinoan sediments. The large unconformity known as `The South Ranges Movement' that is evident in much of the former Centralian Superbasin may testify to such an orogenic event having occurred. Previous studies of detrital zircons in the region provide support for this conclusion.
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ItemHeat flow modelling in the Adelaide Geosyncline, South Australia and implications for geothermal resource exploration( 2008)The central theme of this research is the continental heat flow at the surface of the Earth. Radioactive heat production in the lithosphere and heat flux from convection in the asthenosphere are first order controls on surface heat flow. Accurate heat flow determinations are essential in understanding the geodynamics of the lithosphere and refining resource exploration models, in particular those related to geothermal resources. The focus of this investigation is confined to the understanding of heat refraction as a result of the heterogeneity and anisotropy of the geological subsurface, under a steady-state heat conduction regime. Within the South Australian Heat Flow Anomaly, an area of particular significance for geothermal resource exploration is the deep seated Torrens Hinge Zone, a strip of tectonic transition between the Archaean Gawler Craton to the west and the Neoproterozoic to Cambrian sedimentary cover of the Adelaide Geosyncline to the east. (For complete abstract open document)
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ItemAltitudinal distribution of vegetation in the headwaters of the Wongungarra River, Victoria( 1993)Changes in vegetation composition with respect to altitude were investigated in the sclerophyllous forests of the Australian mountain region. Vegetation was surveyed at 148 sites along two transects which were located to maximise variation in altitude and minimise the influence of environmental factors not directly related to altitude. The measurement, simulation, and estimation of environmental variables revealed that this aim was met except at the end-points of the transects where secondary influences are present.
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ItemGeology and tectonothermal history of The Fishery Bay Region, Eyre Peninsula, South Australia( 1998)The Fishery Bay region, southern Eyre Peninsula, South Australia, consists of Archaean charnockitic and paragneissic sequences of the Sleaford Complex intruded by Palaeoproterozoic granitoids and two generations of mafic dykes. These rocks preserve the deformational and metamorphic effects of the Kimban Orogeny and the later Wartakan Event. Within the Fishery Bay area, five separate ductile deformation events (D1-D5) are recognised, the dominant of which (D2-D3) are associated with granulite facies metamorphism. The effects of the D3 event are pervasive throughout the Fishery Bay region, with D1 and D2 preserved only in regions of low-D3 strain. The overprinting nature or D3 is recognised in the reorientation of D2 structures. The dominant response of the area to D3 strain is a series of westerly-dipping dextral oblique reverse shears with west block-up movement. Much of the strain is localised within the paragneisses and along the margins of mafic dykes recognised in the development of a NNE-trending D3 high-strain zone termed the Cape Wiles Shear Zone. D3 observations from the Fishery Bay region correlate well with previous studies conducted on southern Eyre Peninsula which lead to the inference that D3 west block-up exhumation is responsible for the positive pressure gradient that exists from west to east across the Kalinjala Shear Zone. The pressure-temperature conditions preserved in the mineral assemblages of the paragneiss units and mafic dykes record two granulite facies metamorphic events, M2 and M3. Mineral assemblages associated with M2 and M3 are similar and passage from M2 to M3 did not result in reaction textures which indicates the proximity of the thermal conditions of these two metamorphic events. M2 corresponds to the second deformational event (D2) where peak metamorphic conditions reached pressures of 8.6±3.2 kbar at 750-900°C, The second thermobaric event correlates with the third deformation event (D3) and a metamorphic peak of 4.1±1.9 kbar at 750-850°C. The decompression of the Fishery Bay region during D3/M3 is synchronous with crustal thickening of the terrain east of the area.
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ItemThe geochronology and thermochronology of the Brockman Creek 01, Melita 01 and Melita 02 kimberlites, Western Australia( 2000-10)Due to the difficulties inherent in dating kimberlites, two independent methods are employed to confirm the unusually old ages of approximately 2 Ga for three occurrences in Western Australia. Phlogopite micas from three kimberlites were dated using 40Ar/39Ar and 87Rb/86Sr dating techniques in order to provide an estimate of the intrusion ages. The high reliability of the age estimates is indicated by the similar results produced by the 87Rb/86Sr method. Argon loss is suspected for phlogopite samples, resulting in the apparently reliable 40Ar/39Ar total fusion ages that do not correspond to previously determined emplacement ages. (For complete abstract open document)
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ItemThe potential for natural attenuation of petroleum hydrocarbons in groundwater: Shell Newport Terminal, Victoria( 2000-10)Groundwater in the fractured and jointed Quaternary Newer Volcanics basaltic aquifer system beneath the Shell Newport Terminal has been contaminated by petroleum hydrocarbons. This petroleum hydrocarbon contamination has resulted from a number of different spill incidents over the terminal's long operation. Petroleum hydrocarbon contamination has led to the formation of a light nonaqueous phase liquid (LNAPL) floating on the water table. Associated dissolved and vapour phases have also developed within the basaltic aquifer. The effectiveness of natural attenuation processes to remediate the petroleum hydrocarbon contamination has been evaluated based on the gas chromatography / mass spectroscopy analysis of LNAPL samples and changes in groundwater geochemistry. Three distinct LNAPL plumes were identified within the Shell Newport Terminal jet facility plume (kerosene source); off-site plume along High 8t (mixed source of leaded petrol, kerosene, and diesel); and black oil fuel gantry plume, which is migrating off-site to Digman Reserve (mixed source of leaded petrol, shell sol A, and diesel). LNAPL ratio analysis revealed only that the samples were degraded compared to their estimated source composition. Further interpretation of ratios was difficult due to constraints involved in source compositions, sampling limitations, heterogeneity of the groundwater system, and high transport velocities of the groundwater compared to LNAPL migration. (For complete abstract open document)
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ItemHydrogeology of the newer volcanic basalt aquifer at the Shell Terminal Newport Victoria( 2000-10)The Shell Terminal at Newport, Victoria and adjacent areas have been intensively used as terminals for large petroleum companies (BP,Ampol,Caltex, Mobil and Shell) for many years. As a consequence the groundwater is contaminated with light non-aquaeous phase liquids (LNAPLs) and an associated dissolved phase.