Copies of author's previously published articles inserted. / Bibliography: leaves 142-159. / xiv, 159, [47] leaves : ill., maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Focuses on understanding the controls of distribution of continental deformation from the perspective of structural and metamorphic investigations, using the 500 Ma Adelaide Fold Belt in South Australia as a case study. Of particular interest is the relative roles of compositional, thermal and structural controls on the distribution of deformation at the scale of an orogen. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1999?

2 fold. maps and reprint of Journal article in end pocket of vol. 2. / 2 v. : photos., diags., maps ; 31 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Mineralogy, 1979

Copies of author's previously published articles inserted. / Bibliography: leaves 142-159. / xiv, 159, [47] leaves : ill., maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Focuses on understanding the controls of distribution of continental deformation from the perspective of structural and metamorphic investigations, using the 500 Ma Adelaide Fold Belt in South Australia as a case study. Of particular interest is the relative roles of compositional, thermal and structural controls on the distribution of deformation at the scale of an orogen. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1999?

No description available.

The nature of the Ediacaran macrobiota (c. 580-541 Ma) remains puzzling. These first assemblages of large, complex fossils may have included early animals; giant microbial forms; and organisms representing radically different body plans that went extinct. Discoidal impressions – some forming the base of Ediacaran fronds but most found as isolated discs – dominate the Ediacaran macrobiota. However round markings may also be formed in a variety of abiogenic ways. This study investigates the nature and biogenicity of discoidal impressions from two Ediacaran successions: the c. 560-Ma upper Burway Formation, Longmyndian Supergroup, Shropshire, UK; and several sites on the Bonavista and Avalon Peninsulas, Newfoundland, Canada, ranging in age from 565–c. 560 Ma. The investigation involved fieldwork, photography, serial grinding through cross-sections, and optical and scanning electron microscopy. It concludes that several Longmyndian discoidal forms are pseudofossils formed by sediment injection resulting from small-scale fluid escape inferred to be driven by microbial mat sealing. Turning to clearly biogenic impressions, comparison of the varied morphologies of holdfast discs associated with fronds preserved under ash and sand from several Newfoundland sites leads to a generic model of their architecture as consisting of enclosed chambers, a complex construction perhaps for strength or possibly symbiosis. Detailed observations of the rayed disc Hiemalora suggest that it may have had an amoeboid lifestyle. Finally, the key Ediacaran taxon Aspidella is separated from the discs Ediacaria and Spriggia, with which it has been synonymized, and interpreted as a possible polyp-like animal capable of limited movement. This thesis thus demonstrates that the earliest reported Ediacaran discoidal impressions are abiogenic, produced by mat-influenced processes particularly relevant to the Precambrian, and proposes models and interpretations for several key Ediacaran forms that have important implications for both the nature and diversity of the Ediacaran macrobiota, and early animal evolution.

Iron-formations are ferruginous sedimentary rocks which have their source from fumarolic activity associated with submarine volcanism, with deposition of iron as oxides, hydroxides, and hydrous oxide-silicate minerals in shallow and/or deep marine sedimentary systems. The Precambrian ironformations of southern Africa have a wide age range, but are more prominently developed before 1.SGa. These iron formations occur in greenstone belts of the Kaapvaal and Zimbabwean cratons, in the Limpopo mobile belt, in cratonic basins and in the Damara mobile belt. The Archaean-Proterozoic sedimentary basins and greenstone belts host iron ore deposits in iron-formation. Iron formations have a lengthy geological history. Most were subjected to intense, and on occasions repeated, tectonic and metamorphic episodes which also included metasomatic processes at times to produce supergene/hypogene high grade iron ores. Iron-formations may be enriched by diagenetic, and metamorphic processes to produce concentrating-grade ironformations. Uplift, weathering and denudation, have influenced the mineral association and composition of the ores, within which magnetite, haematite and goethite constitute the major ore minerals. The iron resources of the southern Africa region include the Sishen deposits, hosting to about 1200 Mt of high grade direct shipping ore, at >63% Fe. Deposits of Zimbabwe have more than 33 000 Mt of beneficiable iron-formation. The evaluation of an iron ore prospect involves many factors which must be individually assessed in order to arrive at an estimate of the probable profitability of the deposit. Many of these are geological and are inherent in the deposit itself. Other factors are inherent aspects of the environment in which the ore is formed. Although the geological character of the ore does not change, technological advances in the processing techniques may have a great effect on the cost of putting the ore into marketable form. Geochemical, geophysical and remote sensing methods would be used for regional exploration. Chip sampling and drilling are useful for detailed exploration. Purely geological exploration techniques are applicable on a prospect scale in the exploration of iron ore deposits. Regional exploration targeting should choose late Archaean greenstone belts containing oxide facies iron-formation or Early Proterozoic basins located at craton margins as they are both known to host high-grade haematite orebodies formed by supergene/hypogene enrichment. Most types of iron ore deposits in southern Africa are described and classified. An attempt is made to emphasize the major controls on mineralisation, in the hope that these may be applicable to exploration both in the southern African region and within analogous settings around the world.

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<p> The northwestern Melville Peninsula in the area of 69°34'N/84°50'W consists of Precambrian Shield rocks that have suffered multiple metamorphic events, including a high grade metamorphic event in the late Archean, ranging from upper amphibolite to granulite grade locally. The oldest unit present is a tonalite-granodiorite-granite suite showing both foliation and lineation and a somewhat migmatic texture. This biotite-hornblende orthogneiss has produced a Rb-Sr whole rock age date of 2.55 +/- 0.2 Ga. Field relationships indicate that this is a metamorphically induced age rather than an emplacement age. A coarse grained granitic pegmatite associated with the orthogneiss has produced a Rb-Sr isochron indicating an age of 1.83 +/- 0.06 Ga. Petrographic and field evidence indicate that this represents the emplacement age of the pegmatite. </p> / Thesis / Bachelor of Science (BSc)