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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ItemGeologic and geomorphic applications of Aster satellite imagery, northern Flinders Ranges, South Australia( 2002)Multispectal ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) satellite data has been evaluated for geologic and geomorphic interpretations within the northern Flinders Ranges, South Australia. ASTER is a new remote sensing imaging system on board NASA’s Terra satellite, launched in December, 1999. ASTER measures the reflectance of the Earth’s surface within 14 bandwidths of the visible, near infrared, short wave infrared and thermal infrared sections of the electromagnetic spectrum, with a minimum spatial resolution of 15 m. ASTER has the ability to produce digital elevation models (DEM), important for understanding the dynamics of the landscape by draping false colour images over topography. The northern Flinders Ranges is one of the most diverse geological settings on the Australian continent, making it an ideal ‘test site’ to demonstrate the capabilities of the ASTER instrument. The area contains a range of geology from Precambrian basement to Quaternary desert landforms. The ability of ASTER Level 1B data to discriminate between the large range of lithologies is assessed. Geomorphic interpretations made from exploiting the high resolution ASTER data and DEM has revealed a significant record of post Pliocene landscape development, attributed to a combination of climatic and tectonic factors. Such features as incision morphology and the identification of palaeodrainages have enabled constraints to be placed on the Quaternary degradational and aggradational events. For example, estimates of Quaternary sediment flux rates in some areas of the study area are essentially extracted from ASTER DEM data. ASTER has persisted to be extremely useful in the study of aeolian landform morphology in regions surrounding the northern Flinders Ranges. The short wave infrared has proved useful for identifying areas of high surface moisture, directly relating to the depth to water table. The application of principal component analysis to ASTER short wave infrared data is used to accurately identify specific mineralogical character.
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ItemThe stratigraphy and palaeontology of Cape Vani, Milos, Greece( 2005)Milos, dominated by Pliocene-Recent explosive calc-alkaline volcanics, is in the active Aegean Arc. This project investigated the microfauna and depositional environment of a sequence associated with the only terrestrial white smoker field in the world. White smokers occur in a volcaniclastic-hosted Mn-Fe-Ba deposit in a 1 km2 rift basin associated with dacite intrusives. Although the sediments are extensively hydrothermally altered, they have sedimentary structures and yield a variety of micro- and macrofossils. The typical microfaunal assemblage comprises Miliolinids (e.g. Quinqueloculina spp.; Triloculina spp.) and Elphidiids (Elphidium spp.). In the absence of any planktonic foraminifera, this assemblage is typical of inner shelf palaeodepths from around 10-50m. The occurrence of this fauna with echinoderm spines indicates an open marine setting with normal salinity levels. The associated coarse-grained burrowed facies with symmetrical ripples and hummocky cross stratification and a macrofauna of molluscs (e.g. pectinids, Mytilus, fish teeth) further indicates a shallow marine setting. Terrestrial artiodactyl megafauna occur at three levels in tuff and trough cross-laminated fluvial deposits suggesting close proximity to a regressive shoreline. Macrofauna were probably killed by tephra, rapidly disarticulated and removed into a shallow marine environment. The sequence is unconformably overlain by coarse-grained alluvial fan to braided river deposits deposited when Milos became emergent. Barite-silica white smokers derive from the ingress of and leaching by seawater into basement and overlying volcanics. Palaeontological-boiling data shows the fluid was at 165-140°C and the extremophile echinoderm spicule microfauna dominated because forams were unable to live in warm silica-laden turgid fluids with a high heavy metal content.
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ItemSedimentology of the late Neoproterozoic Patsy Springs Canyon, Flinders Ranges, South Australia( 2003)The Neoproterozoic Patsy Springs Canyon is located within the northern portion of the Adelaide Geosyncline, South Australia. The sedimentary structures found within the canyon fill are consistent with a deep marine origin, and include syn-sedimentary marine phosphates, marine cements, sandstones with partial Bouma sequences, abundant mudstones and various mass flow deposit types (including grain flows, debris flows and slumps). Structures indicative of tidal activity (previously interpreted to be of shallow water origin) are interspersed with Bouma sequences and mass flow deposits and are here interpreted as having been produced by deep-water tidal bottom currents. Rare structures resembling hummocky cross stratification are here interpreted as similarly being of deep-water origin. This deep water interpretation for the canyon fill contradicts previous shallow water models and alleviates the need for extraordinary changes in base level, required by such shallow water models. A deep-water submarine origin for the canyon is also more consistent with the lack of canyon-synchronous basin-wide unconformity and is more consistent with an open-ocean palaeogeography. This study has resolved some of the ambiguity surrounding the origin of the Wonoka canyons by providing sedimentological evidence to suggest that they may in fact represent ancient submarine canyons.
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ItemOrigin and formation of Ordovician sedimentary phosphates at Phosphate Hill, Mansfield, southern Australia( 2002)Ordovician sedimentary phosphatic rocks were mined for fertilizer use in the 1920’s from a small, highly deformed belt of Ordovician rocks at Phosphate Hill, near Mansfield (Warburton, 1:250,000 topographical map). The formation of the phosphate and the environmental conditions at the time of its formation have not been previously discussed in detail. It is an example of a sedimentary phosphate deposit that displays the results of both primary phosphogenesis and secondary, reworking processes. The black shale lithologies are host to the primary phosphate formation in the form of concretionary phosphates, derived from the high phosphorous content of bottom waters and the shells of the phyllocarid crustacean Caryocaris. Caryocaris has been misidentified in previous studies and their importance as the dominant bioclast at Phosphate Hill, has not been realised until now. Phosphorous enrichment within the depositional environment resulted from the extremely high organic contents within marine waters, which is illustrated by the bituminous character of some of the black shale lithologies. The depositional environment was relatively low energy, with low sedimentation rates, in isolated and stagnant marine waters. Thin alternating shale and phosphatic sand lithologies were derived from changes in the energy levels of the depositional environment which led to small turbidity currents reworking the concretionary phosphates and forming clastic phosphatic grains. Phosphate Hill has been extensively folded, fractured and faulted, with near-surface exposure resulting in the episodic precipitation of alumino-phosphatic, hydrous mineral phases. Phosphate Hill is compositionally similar to the Cheshunt sedimentary phosphate occurrence in Victoria, reflecting a similarity in environmental conditions within the Ordovician depositional marine environment.