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published_or_final_version / Applied Geosciences / Master / Master of Science

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Thesis (M. Sc.)--University of Adelaide, Dept. of Economic Geology, 1985. / Includes bibliographical references (leaves 48-51).

Thesis (doctoral)--Universität Göttingen, 1974. / Vita. Includes bibliographical references (p. 112-125).

Thesis (Ph.D.)--York University, 2005. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves196-212). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNR11592

Magister Scientiae - MSc / In areas of transported overburden there is frequently a weak relationship between soil and the underlying mineralized bedrock. Vegetation has the capability to absorb metals from the underlying substrate via its extensive root systems. These metals are translocated to the various organs of the plant such as leaves, twigs bark and roots without negatively impacting on the normal functioning of the plant. The analysis of the vegetation may therefore be used to locate deeply buried mineral targets. The main focus of this investigation was to determine the suitability of A. karroo and B. albitrunca for biogeochemical prospecting for gold in the Blue Dot Mine area. The appraisal of the suitability for both plant species requires an understanding of element absorption and distribution patterns in relation to variable composition of bedrock and associated underlying gold mineralization. / South Africa

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Marginal zones of salt diapirs and canopies are complex geological environments, with rapid spatial variations in lithology, strain, and fluid-assisted alteration. These complex zones can contain economically attractive hydrocarbon accumulations. However, they are difficult to image seismically due to the irregular geometry of salt bodies and the large property contrast between salt and the surrounding sediments. I present an integrated and multiscale approach to build realistic models of salt margins that represent the geological heterogeneity and seismic anisotropy in such complex zones. Structural field data and petrophysical measurements are used to constrain such models. A suite of evaporite samples of various compositions are used to predict the seismic anisotropy from their crystal preferred orientations (CPOs) and elastic properties. Ultrasonic seismic velocities are measured to calculate the relative contribution of the shape preferred orientations to the seismic anisotropy of such samples. Calculation of the seismic anisotropy produced by thinly interlayered evaporites provides a link between small-scale compositional heterogeneity with large-scale seismic anisotropy. Integration of outcrop structural models, petrophysical measurements and the characterisation of seismic anisotropy of salt is possible through seismic modelling. My results suggest that the seismic anisotropy of these samples is strongly controlled by their CPOs, which ranges from 3 to 7% for halite, from 8 to 10% for anhydrite, and from 13 to 22% for gypsum. Predictions indicate that the contribution of a small amount (< 10 %) of anhydrite can moderately alter the seismic anisotropy of polycrystalline evaporite. A small amount of anhydrite interlayered with halite yields anisotropy parameters with magnitudes of = −0.014, = −0.044, and = −0.193, which agree with those parameters calculated for polycrystalline salt. Such calculations of seismic anisotropy at grain scale enable the study of the propagation of seismic waves through salt margins. Seismic images generated from outcrop models of salt diapir flanks show moderate image degradation if anisotropy of salt is neglected during seismic migration. This methodology provides a foundation for the characterisation of seismic anisotropy of salt with which models of salt margins can be improved.