School of Earth Sciences - Theses
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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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ItemMobility of base metals through regolith, Broken Hill, N.S.W.( 1993)Regolith profiles over and around zones of Pb-Zn mineralisation were investigated at Maybell and Stirling Vale, located in the Broken Hill region, N.S.W. Metasediments and metavolcanics of the Proterozoic Willyama Supergroup crop out in the study areas, with quartz-gahnite horizons hosting mineralisation. Desert loam soils in the study areas have a transported origin. Locally transported sheetwash deposits overlie a relict aeolian deposit which sits on relatively fresh Proterozoic bedrock. Mineralogy of the regolith profile is consistent with depth and landscape position. Quartz-gahnite horizons form topographic highs in both areas, containing up to 13.5% Zn. Gossanous material is associated with the quartz-gahnite rocks. No base metal containing secondary minerals were present in this weathered material but there were high proportions of iron oxides containing substantial amounts of base metals. Surrounding soils were anomalous in Zn, Cu and their pathfinders Cd and As, which outlines a mobilisation of base metals. Similar anomalies were expressed in stream sediments. Calcrete in the area, contained no anomalous levels of Zn, due to the low solubility of Zn at high pH. The majority of base metals in soils were associated with amorphous iron oxides and silicates (presumably gahnites). These metal bonding sites indicate, dispersion haloes in the regolith are due to a combination of physical and chemical dispersion. In this example of transported regolith profiles in an arid terrain, Zn and Cu are both physically and hydromorphically dispersed from weathering quartz-gahnite horizons.
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ItemThe Buchan group sediments and their application to industrial uses( 1993)Technological advancements in the paper industry, which utilise calcium carbonate rather than kaolin as coaters and fillers, is the motivation behind establishing suitable limestone resources in Victoria. The relatively pure Buchan Group Limestones in East Gippsland have practical applications in this industry. The two major controls on the geochemistry of the carbonates are: a) the depositional environment; b) the diagenetic history. The two main units analysed, including the Buchan Caves Limestone, and the Murrindal Limestone, have been deposited in environments conducive to the formation of relatively clay-poor carbonates. The predominant low-energy subtidal conditions prevailing in the deposition of the Buchan Caves Limestone, permitted higher concentrations of clay and organic matter. The Murrindal Limestone harbours sediments that are both clay-rich (McLarty Member) as a result of quiet lagoonal conditions, and extremely clay poor (Rocky Camp Member), the consequence of a high-energy, biohermal environment. In both units, burial and diagenesis are the mechanisms by which further impurities are added, transported or transformed throughout the carbonate profile. Statistical evaluations with respect to the calcium oxide, content, indicate that the Rocky Camp Member is a very high- grade resource. Both the Buchan Caves, and the McLarty Member Limestones are variable grade resources which vary from low- to highgrade. However, Si02,, Fe203, MnO, and MgO content determines the potential application of the Buchan Group Sediments to the paper industry. In all units, mean contaminant values are high, and generally exceed the specifications of the paper industry for fillers and coaters. Potential quarry locations are identified at Murrindal and in South Buchan. These sites offer a combination of very high-grade limestones, relative lack of impurities, and conform to the regulations of quarry development operations.