School of Earth Sciences - Theses

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    The geology and geochemistry of the Agnew Intrusion: implications for the petrogenesis of early Huronian mafic igneous rocks in Central Ontario, Canada
    Vogel, Derek Christian ( 1996-07)
    The Early Proterozoic Agnew Intrusion is a well-preserved leucogabbronoritic to gabbronoritic layered intrusion that is a member of the East Bull Lake suite of layered intrusions (ca. 2490-2470 Ma) occurring in central Ontario. These intrusions are related to the development of the Huronian Rift Zone, which may be part of a much more widespread rifting event that involved the Fennoscandian Shield. Structural data suggest that these intrusions have been subjected to ductile deformation and are erosional remnants of one or more sill-like bodies originally emplaced along the contact between Archaean granitic rocks of the Superior Province and an Early Proterozoic Huronian continental flood basalt sequence in the Southern Province.
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    The development of a high quality historical temperature data base for Australia
    Torok, Simon James ( 1996)
    A high quality, historical surface air temperature data set is essential for the reliable investigation of climate change and variability. In this study, such a data set has been prepared for Australia by adjusting raw mean annual temperature data for inhomogeneities associated with station relocations, changes in exposure, and other problems. Temperature records from long-term stations were collaborated from the set of all raw data held by the Australian Bureau of Meteorology. These long-term records were extended by combining stations and manually entering previously unused archived temperature measurements. An objective procedure was developed to determine the necessary adjustments, in conjunction with complementary statistical methods and station history documentation. The objective procedure involved creating a reference time series for each long-term station, from the median values at surrounding, well-correlated stations. Time series of annual mean maximum and mean minimum temperatures have been produced for 224 stations, and the adjusted dataset has been made available to the research community. The adjusted data are likely to be more representative of real climatic variations than raw data due to the removal of discontinuities. The adjusted data set has been compared with previously used temperature data sets, and data sets of other parameters. The adjusted data set provides adequate spatial coverage of Australia back to 1910. Additional adjusted data are available prior to this date at many stations. Trends in annual mean maximum, minimum, the mean of the maximum and minimum, and the range between the maximum and minimum, have been calculated at each site. Maximum and minimum temperatures have increased since about 1950, with minimum temperatures increasing faster than maximum temperatures.
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    Transport, attenuation, and degradation of organic chemicals in a basaltic aquifer system near Melbourne, Australia
    Finegan, James Michael ( 1996)
    Groundwater in the Pliocene to Pleistocene fractured and jointed Newer Volcanics basaltic aquifer system beneath Melbourne's industrialised western suburbs is extensively contaminated by a wide variety of organic and inorganic compounds. Groundwater in Tertiary sediments underlying the Newer Volcanics is probably also contaminated by the same sources. The main objectives of this research were 1) to assess the types, concentrations, and distribution of contaminants in the Newer Volcanics aquifer system in Melbourne's western suburbs and at a selected contaminated site and 2) to determine contaminant transport, attenuation, and degradation processes affecting organic contaminants in this aquifer system. Contaminants detected in the Newer Volcanics aquifer system during this research include phenols, volatile organic compounds, polynuclear aromatic hydrocarbons, polychlorinated biphenyls, metals, and inorganic anions. The groundwater flow system in the study area comprises a single heterogeneous and anisotropic unconfined aquifer, and includes both the Newer Volcanics and underlying sedimentary units (the Brighton Group and the Werribee Formation), although hydraulic connection of these units to the volcanics is irregular. Groundwater flow in the Newer Volcanics is through vesicular and/or scoriaceous lava flow tops and bottoms, in intercalated fluvial deposits, and through the fractured and jointed lava flows. Locally (scale of less than I km square), the basaltic aquifer system may consist of hydraulically separated shallow and deep aquifer zones that are connected on a larger scale. The deep aquifer zones may be semi-confined to confined. Groundwater in the study area is recharged via throughflow from upgradient and infiltration of rainfall. Discharge from the Newer Volcanics in the study area is primarily to underlying sedimentary formations, but also to surface water features and directly to Port Phillip Bay. Several mechanisms which reduce contaminant concentrations are possible in the Newer Volcanics aquifer system. These include volatilisation, dispersion and diffusion, transient storage, matrix diffusion, sorption, hydrolysis, and biodegradation. However, the nature of porosity in the Newer Volcanics may significantly extend the lifetime of contaminant plumes via the processes of transient storage and matrix diffusion. The primary mechanisms of attenuation and degradation of organic contaminants in the Newer Volcanics aquifer system are probably biodegradation, matrix diffusion, sorption, and dispersion (for non-reactive contaminants) in order of decreasing effect. Biodegradation at the water table and discharge areas will also be significant because of atmospheric contact and increased dissolved oxygen concentrations. Because of the relative lack of organic carbon in the basaltic aquifer system, sorption will occur mainly to mineral surfaces in clay-rich zones and within the rock matrix (concurrent with matrix diffusion). In some cases, relatively undiluted contaminants may be transported along preferred flow paths to discharge locations where they may pose a potential threat to the environment prior to degradation or attenuation. It was found, at least with phenols and volatile organic compounds in groundwater at a study site, that contaminants are degraded and/or attenuated rapidly, probably via biodegradation, matrix diffusion, and sorption. Biodegradation testing of groundwater at this study site confirmed the existence of microorganisms in the aquifer system capable of aerobic degradation; indirect evidence may indicate the presence of anaerobes.