The Ecca Group of Karoo Supergroup is a sedimentary rock sequence that deposited between the Late Carboniferous (Dwyka Group) and the Late Permian-Middle Triassic (Beaufort Group). The Ecca Group investigated in this study is situated in the Eastern Cape Province of South Africa and it comprises mainly of shales, mudstones, siltstones and sandstones. The Ecca Group sequence contains considerable carbon content and suitable thickness to make it an ideal target for shale gas exploration. Previous studies put more emphasis on the geology and stratigraphy of the Ecca Group, this study revised the stratigraphy, and put new insight on the petrography, depositional processes, sedimentary facies, provenance, paleoweathering, tectonic setting, subsidence rates and history, electrical resistivity, source rock characteristics and diagenesis of the potentially feasible sandstone and mudrock reservoir rocks of the Ecca Group. Based on the lithological features, sedimentary structures and facies characteristics, the stratigraphy of the Prince Albert, Whitehill, Collingham and Fort Brown Formations of the Ecca Group is now subdivided into two informal members each, i.e. Lower Member and Upper Member. Furthermore, the Ripon Formation is now subdivided into three informal members. Each member has been asigned a lithological name. The grain size parameters show that most of the Ecca Group sandstones are very fine to fine grained, poorly to moderately well sorted, mostly near-symmetrical and mesokurtic in grain-size distribution. The linear discriminant function analysis is dominantly indicative of turbidity current deposits under deep marine environment for Prince Albert, Whitehill and Collingham Formations, shallow marine environment for Ripon Formation, while the Fort Brown Formation is lacustrine-deltaic deposits. Modal composition analysis and petrography studies revealed that the detrital components of the sandstones are dominated by monocrystalline quartz, feldspar and lithic fragments. The sandstones are compositionally and texturally immature and can be classified as feldspathic wacke and lithic wacke. The provenance analysis revealed plutonic and metamorphic terrains as the main source rocks with minor debris derived from recycled sedimentary rocks. The detrital modal compositions of these sandstones are related to back arc to island and continental margin of tectonic setting. Based on the detailed sedimentological analyses of outcrop and borehole data, fourteen lithofacies were identified and seven facies associations (FAs) were recognised. The facies associations are: FA 1: Shale and mudstones intercalated with siltstones, FA 2: Carbonaceous shale, mudstone with subordinate chert and sandstone, FA 3: Mudstones rhythmite with thin bedded mudstone and lenticular siltstone, FA 4: Greyish medium bedded sandstone intercalated with laminated mudstone, FA 5: Dark-grey medium to thick bedded mudstone and siltstone, FA 6: Thin to medium bedded sandstone alternated with thin bedded carbonaceous mudstone, and FA 7: Varved mudstone rhythmite intercalated with siltstone and minor sandstone. Sedimentological characteristics of the identified facies associations indicate four deposition environments, namely, deep marine basin, turbidite, shallow marine and lacustrine environments, which constitute a gradually regression sequence as a result of sea-level dropping and shallowing of the basin during the developmental processes. Geochemical analysis of the Ecca mudrocks and sandstones revealed that the rocks are of quartzose sedimentary provenance, suggesting that they were derived from a cratonic interior or recycled orogen. The petrography and geochemistry of the sandstones indicated that the source areas are composed of plutonic and metamorphic rocks with a minor component from sedimentary rocks. The geochemical diagrams and indices of weathering suggested that the granitic source rocks underwent moderate to high degree of chemical weathering. The tectonic setting discrimination diagrams support passive continental margin setting of the provenance.

Orientador: Wanilson Luiz Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-10T09:37:28Z (GMT). No. of bitstreams: 1 Nizoli_EricoCasare_M.pdf: 798360 bytes, checksum: a2063e7c4651b7ef1228b1884a953131 (MD5) Previous issue date: 2007 / Resumo: Os estuários são geralmente ambientes redutores, nos quais atividades antrópicas podem resultar em altos níveis de metais nos sedimentos. Nestes sedimentos o sulfeto é uma fase importante no controle da concentração de metais livres, sendo que a maioria dos sulfetos reativos em sedimentos ocorre como bisulfetos e monosulfetos de ferro, sendo estes últimos os mais reativos. Devido à maior insolubilidade dos sulfetos, elementos como Cd, Cu, Ni, Pb e Zn deslocam o Fé do FeS para formar seus respectivos sulfetos, mais estáveis. A razão entre SVA (sulfetos volatilizados por acidificação) e MSE (metais simultaneamente extraídos, extraídos a frio com uma solução diluída de HCl) é freqüentemente utilizada como um indicador do potencial de biodisponibilidade dos referidos metais em sedimento de ambientes anaeróbicos. Quando a concentração molar de SVA excede a concentração dos MSE, a biodisponibilidade não é considerada significativa. O sistema estuarino de Santos-Cubatão tem sido considerado um ambiente sedimentar seriamente poluído, devido à emissão não controlada de efluentes industriais e urbanos. Neste sistema, os sedimentos do rio Morrão contêm expressiva contaminação multi-elementar. Com o objetivo de quantificar a contaminação de metais e verificar o papel do SVA no controle de biodisponibilidade dos MSE no rio Morrão, testemunhos de sedimentos de dois ambientes sedimentares (permanentemente submerso e exposto a atmosfera durante as menores marés) foram amostrados no inverno e no verão. Os resultados mostraram alta concentração de metais totais e metais simultaneamente extraídos (Cd, Cu, Pb, Zn, Ni e Fe), bem como diferenças sazonais no controle da iodisponibilidade destes metais. Condições redutoras e neutras têm favorecido a formação e estabilidade do SVA no estuário estudado. Não foi observada relação entre o tamanho das partículas (granulometria) e a perda por ignição (matéria orgânica) com a concentração de SVA. No entanto, estes fatores demonstraram ser importantes no controle das concentrações de metais totais e MSE, ambas altamente associadas com os sedimentos silte-argilosos. A razão _MSE/SVA foi freqüentemente superior a 1, principalmente no verão, mas uma variação significativa entre os sedimentos expostos e submersos não foi observada. Considerando os sulfetos como os principais elementos controladores da biodisponibilidade de metais em estuários, conclui-se que os sedimentos do rio Morrão apresentam metais biodisponíveis à biota ali existente. Palavras-chave: Geoquímica de sedimentos; sulfetos; metais; estuário / Abstract: Estuaries, in general, reducer environments in which anthropogenic activities could result in high metal levels in the sediments. Sulfides are important phases in the control of the concentration of some free metals in those sediments. The majority of sulfides in sediments occurs as iron bisulfides and iron monosulfide, being the last the most reactive. Due to their higher insolubility, elements such as Cd, Cu, Ni, Pb, and Zn displace iron in FeS to form their respective more stable sulfides. The ratio of AVS (monosulfide analytically denominated acid volatile sulfide) to SEM (simultaneously extracted metals, extracted to cold with a solution of diluted HCI) is frequently used as an indicator of potential sediment bioavailability of those metals in anaerobic environments. Where AVS molar concentrations exceed those of SEM, bioavailability has not been considered significant. The sediments in the estuarine system of Santos-Cubatão have been reported as seriously polluted, due to the uncontrolled emission of industrial effluents and urban wastes. In this system, the sediments of the Morrão River contain expressive multi-elementary concentration. The objective of this study was to quantify the metal contamination and to verify the role of the AVS in the control of the bioavailability of SEM in the Morrão River. Sediment cores from two sedimentary environments (permanently subaqueous and exposed to atmosphere during the lower tides) were sampled in the winter and summer. High total and simultaneously extracted metal concentrations of Cd, Cu, Pb, Zn, Ni, and Fe were recorded, as well as seasonal differences in the control of the bioavailability of these metals. Reducer and neutral conditions favored the formation and the stability of AVS in the studied estuary. No relationship between grain-size and loss-on-ignition (organic matter) in respect to AVS concentrations was observed. However, these factors were important by controlling total-metal and SEM concentrations, both highly associated with silt-clay sediments. The values of _SEM/AVS ratio were frequently > 1, mainly in the summer, but significant variation between exposed and subaqueous sediments was / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências

Several sediment characteristics were analyzed to determine their suitability for use as potential normalization factors for the bioavailability of neutral organic compounds sorbed to sediments. Percent organic carbon, cation exchange capacity and particle surface area were measured sediment characteristics that varied sufficiently to encompass the range in observed sediment toxicity. Laboratory sediment toxicity test data using fluoranthene suggest that there is no biologically significant correlation between sediment toxicity and sediment characteristics (organic carbon, cation exchange capacity, particle size distribution, particle surface area). Fluoranthene amended sediments with similar organic carbon contents do not yield similar toxicities due to sorbed fluoranthene and thus do not support the organic carbon normalization approach for evaluating sediment quality or for sediment criteria development.

Ph.D. (Aquatic Health) / Please refer to full text to view abstract

M.Sc. / Please refer to full text to view abstract

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In the recent years, the shale gas discourse has become central to discussions about future energy supply in South Africa. In particular, the Permian black shales of the Lower Ecca Group formations in the Karoo Basin are considered potential source rocks for shale gas. The research presented in this thesis advances the understanding of the shale gas potential of mainly the Prince Albert, Whitehill and Tierberg/Collingham Formations. These shale sequences were sampled from eight deep boreholes spread across the main Karoo Basin and geochemically analysed at the GFZ - Helmholtz Centre Potsdam, Germany. Three key questions guided the study, these are: (i) what is the lithology of the sequence; (ii) where in the basin do the shale sequences attain maximum thickness at optimum depth i.e. beneath 1000-1500m; and (iii) and their shale characteristics. To evaluate these, borehole core logging, petrology and organic geochemistry were used extensively. Petrology involved the use of thin section, scanned electron and transmission electron microscopy for mineralogy as well as the identification of sedimentary features, organic matter and nano-scale porosity. These were coupled with standard organic geochemistry techniques such as Rock Eval. analysis, open pyrolysis gas chromatography and thermovaporisation to quantify the free gas, total organic carbon (TOC), present-day gas generative potential and kerogen type. The results show that the Whitehill Formation, away from the CFB and not intruded by dolerite, has the most potential for shale gas. Microscopic studies of this pyritic black shale reveal the occurrence of porous amorphous matter, indicating thermal maturity within the gas generation zone (i.e. > 1.1 percent Ro, 120ºC). The TOC content is consistently high within the Whitehill (exceeding industry requirement of 2 percent), attaining maximum of 7.3 percent. The highest yields of free and desorbed gas, especially methane, were emitted within this formation (S1 and nC1 peaks); mostly within its dolomitic units. In addition, dissolution porosity within dolomite units of the Whitehill Formation was identified as the predominant type of porosity. Thus, it is deduced that the dolomitic units of Whitehill Formation potentially contain the greatest volumes of free gas. HI values attain maximum of 25 mg HC/g TOC, whereas the OI values 26 mg CO2/g TOC. Such low HI and OI values are typically attributed to the dominance of Type IV kerogen, and consistent with overmaturity. Open pyrolysis (GC) show the main the chemical compound of the organic matter to be m-p-xylene, consistent with a mix of Type III, Type I/II and Type IV kerogen. Lithologically, the Whitehill Formation is composed of ~ 35 quartz, 13 percent feldspar, 26 percent illite and ~ 23 percent dolomite with variable amounts of pyrite. The dominance of quartz is directly proportional to the brittleness of the rock. Thus it can be deduced that the Whitehill Formation is relatively brittle and therefore fraccable. Burial trends indicate increasing depth (from ground level) to the top of the Whitehill Formation towards the south and south-eastern portion of the basin. It is in the southern region where thicknesses of this black shale exceeding 50m occur at depths more than 1500m; 1000m beneath fresh water aquifers. It therefore concluded that Whitehill Formation in the southern portion of Karoo Basin, but away from the thermo-tectonic overprint of the Cape Orogeny, is the most probable shale gas reservoir in South Africa.

This study investigates the morphologic approach to sediment transport analysis and applies it to the Vedder River, British Columbia. The approach is based on the assumption that changes in channel morphology indicate sediment transport in the river. Despite the connection between these phenomena, only a few studies have examined this relation. The procedures, assumptions and limitations of the morphologic approach are discussed. It is more straightforward to construct a sediment budget for bed material than for wash material, as bed material travels relatively small distances. The Vedder River is a cobble gravel river with dyked banks. Therefore it is a good location for a study of the morphologic approach as bed material can be distinguished easily from wash material. The results of this study are important as aggradation in Vedder River has resulted in major flooding problems. Cross-section survey data were used to estimate volume changes along the Vedder River for incorporation into sediment budgets for several periods over the last decade. The construction of a sediment budget requires knowledge of at least one transport rate or transfer distance. Although the zero downstream transport assumption used in this study was found to be incorrect, it was retained as there are no transport rate measurements. Furthermore, the transport assumption is probably within the error ranges of the sediment budgets. Most of the errors in the sediment budgets were attributed to uncertainty in volume change estimates. When volume change estimates were calculated for different sets of cross-sections, the values varied significantly. This indicates that there is bias in the results. It is difficult to evaluate the degree of bias without a knowledge of actual channel changes. It. was found that the uncertainty in the transport estimates at Vedder Crossing ranged from ±8% to ±25%. These values compare favourably with error analysis results of direct measurements in the Fraser River (see McLean and Church, 1989). An analysis was performed to evaluate the cross-section density that is necessary to obtain a reasonable representation of actual channel changes. The average distance between cross-sections should be relatively smaller in reaches which have large variability in channel change patterns. It was suggested that cross-section spacing in the Vedder River should average between 250 and 300 m. The sediment budget results provide valuable information about the patterns of channel change and the magnitude of flows responsible for large amounts of deposition in the Vedder River. It was found that significant aggradation occurs during exceptional flood events. Most of the material is deposited in the several kilometers immedatiately upstream of the Vedder Canal. The morphologic approach provides a good method for evaluating the sediment transport regime of a river. The usual management time-scale ranges from several years to decades, which is coincident with the time-scale of this approach. Furthermore, the total field effort is less than that required for direct measurements. / Arts, Faculty of / Geography, Department of / Graduate

Orientador: Wanilson Luiz Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-27T06:38:54Z (GMT). No. of bitstreams: 1 Volpato_Juliano_M.pdf: 8591527 bytes, checksum: 58b14d8c8d308419f349e7d957c88674 (MD5) Previous issue date: 2015 / Resumo: A existência de sedimentos altamente enriquecidos principalmente por Fe e P, provenientes das indústrias siderúrgica e de fertilizantes localizadas próximas ao estuário do rio Morrão, um dos principais receptores de efluentes industriais do Sistema Estuarino de Santos-Cubatão (São Paulo Brasil), juntamente com as condições físico-químicos do meio, constitui elementos especiais para avaliar se as condições formadoras de minerais como magnetita, hematita, pirita e vivianita podem ser influenciadas por contribuições químicas antrópicas. Este trabalho analisou as condições de formação desses minerais nos sedimentos superficiais do estuário do rio Morrão, na sua relação com a geoquímica dos sedimentos, condições físico-químicas, texturas sedimentares e conteúdo de matéria orgânica. A coleta de sedimentos de superfície consistiu em uma malha amostral de 10 x 10 m, em três transectos paralelos que cruzaram perpendicularmente o canal do rio Morrão. Os resultados mostraram que os sedimentos do rio Morrão encontram-se enriquecidos em diversos elementos químicos dentre os quais Fe, P, elementos terras raras (ETR) e vários metais-traço. O ambiente sedimentar do rio Morrão mostrou-se favorável à autigênese e coexistência de minerais como hematita, magnetita, pirita e vivianita. As fases minerais hematita e magnetita ocorrem amplamente no ambiente, já as fases minerais pirita e vivianita têm sua distribuição mais restrita. Os locais mais favoráveis à ocorrência de pirita e vivianita foram áreas de menor energia de fluxo, tais como planícies de intermaré lamosa, onde há altos teores de enxofre, ferro, fósforo, matéria orgânica e sedimentos finos / Abstract: The presence of sediments highly enriched by contaminant elements, mainly Fe and P, derived from a steel plant and fertilizer industries located near the Morrão River Estuary, the most anthropogenically influenced estuary of the Santos-Cubatão Estuarine System (São Paulo, Brazil), together with the environment physic-chemical conditions constitute special elements to evaluate if the forming conditions of mineral such as magnetite, hematite, pyrite and vivianite can be influenced by the anthropogenic input into the environment. This work studied the forming conditions of these minerals in the superficial sediments of the Morrão River Estuary in its relation with sediment geochemistry, physicochemical conditions, sedimentary texture, and organic matter content. The sample collection comprised a 10 by 10 meters grid composed of three parallel transects crossing perpendicularly the Morrão River channel. The results showed the sediments of Morrão River Estuary are enriched by several chemical elements among which Fe, P, REE and multiple trace elements. The sedimentary environment of the Morrão River showed to be propitious to the authigenesis and coexistence minerals such as hematite, magnetite, pyrite, and vivianite. Magnetite and hematite broadly occur in the environment, and pyrite and vivianite have restrict distribution. Moreover, the places more favorable to the pyrite and vivianite occurrence are areas with low water flux action, such as the intertidal mudflats, where concentrations of S, Fe, P, organic matter, and fine sediments are high / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências

Concern over sediment toxicity has increased the need for toxicity test information with organisms that inhabit sediments. Oligochaetes are exposed to toxicants through feeding and direct body contact with aquatic sediments. Chronic testing with oligochaetes has historically focused on tubificids with test lengths of one year or more to encompass several generations. Most naidid oligochaetes have generation times of three to seven days and could provide chronic information in a matter of weeks. The cosmopolitan distributed naidid, Pristina leidyi, was evaluated for use as a toxicity test organism. Results of research conducted includes culture methods, effects of temperature on reproduction, growth rates in a reference sediment, acute toxicity tests, and chronic toxicity tests.