Dissertationen zum Thema „Sedimentary“

Orientadores: Frésia Soledad Ricardi Torres Branco, Ismar de Souza Carvalho
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: O Afloramento Santa Irene tem sido considerado um dos mais significativos da Bacia Bauru, na Formação Adamantina, pela abundancia e boa conservação de fósseis associados ali encontrados, como dentes isolados de arcossauros carnívoros associados a fósseis de um dinossauro saurópode herbívoro. Os fósseis foram coletados nos anos de 1997 e 1998, na área rural do Município de Monte Alto - SP, e hoje compõem parte do acervo do Museu de Paleontologia de Monte Alto. Os dentes isolados de tal afloramento são o principal material de estudo deste trabalho, que, acrescidos a outros dados obtidos através da análise das feições bioestratinômicas e geológicas da região, permitiram tecer uma interpretação paleoecológica para o Afloramento Santa Irene. Foram analisados vinte e seis exemplares de dentes de arcossauros carnívoros, sendo dezoito deles enquadrados como Theropoda e oito como elementos dentários pertencentes aos Crocodyliformes. Os dentes de Theropoda se distinguem daqueles de Crocodyliformes por serem os primeiros mais achatados lateralmente, além de apresentarem serrilhas. Foi possível constatar que quatorze dos dezoito exemplares classificados dentro da Subordem Theropoda apresentam características pertencentes à Ceratosauria, família Abelisauridae, e Maniraptora, família Dromaeosauridae. A coleção de dentes de Crocodyliformes coletados no afloramento Santa Irene consiste de oito exemplares em geral cônicos, com estriamento ao longo da carena, podendo ou não apresentar bordos serrilhados e seção basal arredondada, sendo possível classificá-los dentro da família Trematochampsidae. Os fósseis articulados e com pouco desgaste do Aeolosaurus indicam um soterramento parcial logo após a morte ou ainda na fase de destruição de seus elementos não esqueléticos. A observação do afloramento e do seu entorno permitiu deduzir que a região apresentava rios, possivelmente, entrelaçados com deposição sazonal de sedimentos e períodos de estabilidade com a formação de solos incipientes. Durante os períodos interdeposicionais e de formação do solo, nota-se a ocorrência da precipitação de minerais, dando origem à formação de calcretes, resultado de períodos secos marcantes. O afloramento Santa Irene representa a deposição de rios que formavam barras arenosas, nas quais diversos grupos de animais buscavam água e alimento. Conclui-se que estes animais habitavam ou transitavam por aquele ambiente, pois não há sinais de que os fósseis tenham sido transportados até o local no qual foram coletados, mas sim que a carcaça do Aeolosaurus serviu de alimentação para outros animais no local de sua morte. Desta forma, o material analisado permitiu a reconstituição de um retrato impar de um ecossistema a muito extinto
Abstract: The Santa Irene outcrop has been considered one of the most significant of the Bauru Basin, in the Adamantina formation, because of abundance and good preservation of associated fossils found there, as isolated teeth of carnivorous archosaurs associated with fossils of a herbivorous sauropod dinosaur. The fossils were found in 1997 and 1998, in rural areas of the city of Monte Alto - SP, and today compose the collection of the Museum of Paleontology of Monte Alto. The isolated teeth from this outcrop is the main material of this paper, which, together with other data obtained by analysis of biostratonomic and geological features of the region, allowed to make a paleoecological interpretation of the outcrop Santa Irene. Twenty-six copies of teeth of carnivorous archosaurs were analyzed, eighteen of them being classified as Theropodomorpho and eight teeth as belonging to Crocodyliformes. The teeth of Theropodomorpho can be distinguished from those to be the first Crocodyliformes as they are more flattened laterally, besides having serrations. It was found that fourteen of the eighteen specimens classified within the suborder Theropoda fit the characteristics belonging to Ceratosauria, family Abelisauridae and Maniraptora, family Dromaeosauridae. The collection of Crocodyliformes teeth collected from the outcrop Santa Irene consists of eight copies generally conical, with streaking along the keel, presenting or not serrated edges and rounded basal section, being possible to classify them within the family Trematochampsidae. The articulated and with little wear fossils of Aeolosaurus indicate a burial soon after death or during the destruction of its non-skeletal elements. The observation of the outcrop and its surroundings allow deducing that the region had braided rivers with seasonal sediment deposition and periods of stability with the formation of incipient soils. During no deposicional intervals periods and soil formation, can be noted the occurrence of precipitation of minerals, giving rise to the formation of calcrete, result of striking dry periods. The outcrop of St. Irene was formed by rivers that formed sand bars, in which various groups of animals tried to find food and water. It can be deduced that these animals lived or transited through that environment, because there is no evidence that the fossils were transported to the location in which they were collected, but that the Aeolosaurus remains served as food for other animals at his death location. Thus, the analyzed material allowed the reconstitution of an unique portrait of an ecosystem to long extinct
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências

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Foi estudada a influência de cinza de bagaço de cana e rocha sedimentar, adicionadas a um material argiloso, durante o processo de sinterização. O material argiloso e os aditivos foram caracterizados utilizando Difratometria de Raio X, Espectrometria de flurescência de Raio X e Análise Térmica. As amostras de cinza e rocha foram moídas, peneiradas a 0,088 mm e 0,125 mm, respectivamente, e incorporadas nos teores de 0, 20, 40, 60 e 80% em massa ao material argiloso. Foram preparados corpos de prova, prensados uniaxialmente a 19 Mpa, para cada corpo de prova, em uma prensa manual. As peças foram sinterizadas nas temperaturas de 500, 800, 900, 1000, 1100 e 1200º C, usando um forno tipo mufla e, posteriormente, submetidos a análise difratométrica e a ensaios físicos e mecânicos de absorção de água, retração linear de queima, massa específica aparente, perda de massa ao fogo, porosidade aparente e módulo de ruptura à flexão. A difratometria de raios X mostrou que a cinza é composta de material cristalino, predominantemente quartzo; a rocha sedimentar apresentou, além de quartzo, argilominerais micáceos e o material argiloso teve como fase principal a caulinita, contendo ainda hidróxido de alumínio e óxidos de ferro em menores concentrações. A análise química mostrou que, além do silício, a cinza e a rocha sedimentar apresentaram concentrações de óxidos de alumínio, potássio, cálcio, ferro e magnésio, enquanto que no material, os óxidos de silício, alumínio, ferro e titânio foram predominantes. As análises térmicas das diferentes misturas mostraram algumas reações que indicam transformação (inversão do quartzo), decomposição (perda de hidróxidos) e formação de fase (mulita) durante o aquecimento das amostras. Difração de raios X sustentou as hipóteses levantadas nos termograms das amostras...
The influence of sugar cane bagasse ash and sedimentary rock, added to clay material, in the sintering process was studied. The clay material and the additives were characterized by X-ray diffraction, X-ray spectroscopy and thermal analysis. The ash and rock samples were triturated, sieved to 0.088 mm and 0.125 mm, respectively, and incorporated at 0, 20, 40, 60, and 80% in the clay material. Prismatic probes were prepared, each pressed at 19 Mpa in a manual press. The pieces were sintered at 500, 800, 900, 1000, 1100 ans 1200ºC, and then characterized by X-ray diffraction and tests for water absorption, linear shrinkage, apparent specific mass, loss on ignition, apparent porosity and flexural strength. X-ray diffraction showed that the ash was composed of crystalline material, predominantly quartz; the sedimentary rock contained, besides quartz, mica; and the main phase of the clay material was kaolinite, but also contained aluminum hydroxide and iron oxides in lower concentrations. Chemical analysis showed that, besides silicon, the ash and the sedimentary rock also contained concentrations of oxides of aluminum, potassium, calcium, iron and magnesium, while in the clay material, silicon oxide, aluminum, iron and titanium were predominant. Thermal analyses of the different of the mixtures showed some reactions that indicated transformation (inversion of the quartz), decomposition (loss of hydroxides) and phase formation (mullite) during the heating of the samples. X-ray diffraction supported the findings in the thermal analysis of the analyzed samples. The tests showed that both the ash and sedimentary rock worsened the mechanical properties of the clay material, although they contributed to the improvement of other attributes. The presence of quartz in the ash and rock hindered the formation of the mullite phase formed during the sintering process... (Complete abstract click electronic acess below)

Resumo: Foi estudada a influência de cinza de bagaço de cana e rocha sedimentar, adicionadas a um material argiloso, durante o processo de sinterização. O material argiloso e os aditivos foram caracterizados utilizando Difratometria de Raio X, Espectrometria de flurescência de Raio X e Análise Térmica. As amostras de cinza e rocha foram moídas, peneiradas a 0,088 mm e 0,125 mm, respectivamente, e incorporadas nos teores de 0, 20, 40, 60 e 80% em massa ao material argiloso. Foram preparados corpos de prova, prensados uniaxialmente a 19 Mpa, para cada corpo de prova, em uma prensa manual. As peças foram sinterizadas nas temperaturas de 500, 800, 900, 1000, 1100 e 1200º C, usando um forno tipo mufla e, posteriormente, submetidos a análise difratométrica e a ensaios físicos e mecânicos de absorção de água, retração linear de queima, massa específica aparente, perda de massa ao fogo, porosidade aparente e módulo de ruptura à flexão. A difratometria de raios X mostrou que a cinza é composta de material cristalino, predominantemente quartzo; a rocha sedimentar apresentou, além de quartzo, argilominerais micáceos e o material argiloso teve como fase principal a caulinita, contendo ainda hidróxido de alumínio e óxidos de ferro em menores concentrações. A análise química mostrou que, além do silício, a cinza e a rocha sedimentar apresentaram concentrações de óxidos de alumínio, potássio, cálcio, ferro e magnésio, enquanto que no material, os óxidos de silício, alumínio, ferro e titânio foram predominantes. As análises térmicas das diferentes misturas mostraram algumas reações que indicam transformação (inversão do quartzo), decomposição (perda de hidróxidos) e formação de fase (mulita) durante o aquecimento das amostras. Difração de raios X sustentou as hipóteses levantadas nos termograms das amostras... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The influence of sugar cane bagasse ash and sedimentary rock, added to clay material, in the sintering process was studied. The clay material and the additives were characterized by X-ray diffraction, X-ray spectroscopy and thermal analysis. The ash and rock samples were triturated, sieved to 0.088 mm and 0.125 mm, respectively, and incorporated at 0, 20, 40, 60, and 80% in the clay material. Prismatic probes were prepared, each pressed at 19 Mpa in a manual press. The pieces were sintered at 500, 800, 900, 1000, 1100 ans 1200ºC, and then characterized by X-ray diffraction and tests for water absorption, linear shrinkage, apparent specific mass, loss on ignition, apparent porosity and flexural strength. X-ray diffraction showed that the ash was composed of crystalline material, predominantly quartz; the sedimentary rock contained, besides quartz, mica; and the main phase of the clay material was kaolinite, but also contained aluminum hydroxide and iron oxides in lower concentrations. Chemical analysis showed that, besides silicon, the ash and the sedimentary rock also contained concentrations of oxides of aluminum, potassium, calcium, iron and magnesium, while in the clay material, silicon oxide, aluminum, iron and titanium were predominant. Thermal analyses of the different of the mixtures showed some reactions that indicated transformation (inversion of the quartz), decomposition (loss of hydroxides) and phase formation (mullite) during the heating of the samples. X-ray diffraction supported the findings in the thermal analysis of the analyzed samples. The tests showed that both the ash and sedimentary rock worsened the mechanical properties of the clay material, although they contributed to the improvement of other attributes. The presence of quartz in the ash and rock hindered the formation of the mullite phase formed during the sintering process... (Complete abstract click electronic acess below)
Orientador: Elson Longo da Silva
Coorientador: Silvio Rainho Teixeira
Banca: Carla dos Santos Riccardi
Banca: Marcos Augusto de Lima Nobre
O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp
Mestre

The overarching goal of this work was to trace the origins of organic matter as a possible biosignature for early life on Earth. This work documented the petrological, structural, isotopic, elemental and molecular properties of organic matter, in a suite of sediments ranging from the Eoarchean to the Phanerozoic. Particular attention was paid to iron formations which form a major part of the Precambrian sedimentological record. Optical and micro-Raman spectroscopy were used to document the petrological occurrences of organic matter and its associated diagenetic features. Focused ion beam and transmission electron microscopy were used to detail the nanoscale structures of the organic matter. Mass spectroscopic techniques were utilised to measure the isotopic, elemental and molecular properties of organic matter and its petrographically associated carbonate. The timing and possible mechanisms of organic matter formation were investigated and evaluated, against the observed attributes of the organic matter. This work has documented organic matter forming key mineral associations with apatite and carbonate, which point to the diagenetic recycling of biogenic carbon. The diagenetic cycling of organic matter is proposed, to fuel the formation of granules during organic matter, iron and sulphur cycling. This cycling is hypothesised to lead to heterogeneity in organic matter structure and preservation in sediments. Additionally, this work has demonstrated that fluid deposited graphite in metamorphosed sediments may represent redistributed, syngenetic organic matter, shedding light on the controversial origins of graphite biosignatures in Earths oldest rocks. Finally, a detailed study of microfossil structures and their associations with organic matter and biominerals in iron formations was conducted to provide evidence for the preservation of Proterozoic microfossils, and the earliest signs of life on Earth.

Theoretical models for the evolution of extensional sedimentary basins make a number of simple, testable predictions for subsidence behaviour. These are that active extension (the syn-rift) will generally be accompanied by rapid subsidence on the downthrown side of normal faults. Once faulting has ceased (the post-rift) the entire basin is predicted to subside at an exponentially decreasing rate, driven by the cooling and thickening of the lithosphere. The aim of this thesis is to determine the significance of second-order departures from this predicted subsidence. Three periods of North Sea subsidence appear to violate these simple predictions: anomalously slow Late Jurassic/Early Cretaceous subsidence, which marks the syn-rift/post-rift transition, and two periods of accelerated post-rift subsidence during the Early Paleogene and Plio-Quaternary. Subsidence data from over 300 boreholes from several basins with different rifting histories on the Northwest European continental plate have been analysed to determine the spatial and temporal distribution of these and other second-order subsidence anomalies. Uncertainties and errors in the observed subsidence calculations cannot explain the anomalous behaviour recognised. The periods of apparently anomalous subsidence are, instead, shown to be the result of geological or tectonic processes that modified either the subsidence history or record of subsidence of the basins studied. Apparent slow Late Jurassic/Early Cretaceous subsidence in the North Sea was the result of well siting and sediment starvation. Analysis of wells from the downthrown side of normal faults in several basins reveals an excellent correlation between rapid subsidence (often >1000m in 10My) and active extension (as documented from other sources of geological information). This was obscured by intense sediment starvation (sedimentation rates <20m/My) in the Central North Sea during Late Jurassic times which generated the apparent subsidence anomaly. Sedimentation rate maps reveal an expansion of the area of sediment starvation during late Jurassic times and into the Early Cretaceous. Cretaceous to Recent sedimentation patterns were then dominated by the interplay between the location and erosion history of extra-basinal sediment source areas and the remnant underfilled Jurassic rift topography.

Submarine canyons are one of the most dramatic morphological features on continental margins and enable sediment transport from the shelf to the deep sea; however, the exact processes operating within submarine canyons are poorly understood. Much of our understanding of the dynamics of sediment-laden flows in submarine canyons results from making inferences from the deposits that they leave behind in the geological record. This thesis aimed to better understand what deposits can reveal about flow processes and ultimately to test the validity of this approach for reconstructing flow dynamics. This aim was achieved by 1) analysing seafloor bedforms, 2) the detailed lithological and ichnological analysis of submarine canyon deposits, and 3) utilising turbidity current monitoring data. Construction and analysis of a global database of seafloor bedforms suggests that bedforms across all scales and a wide variety of settings can be generated by supercritical flows. The most complete dataset of monitored turbidity currents in a submarine canyon was combined with precisely located vibracores collected in Monterey Canyon. The combination of these datasets demonstrates that deposits can be used to accurately infer flow properties, and the data were further used to develop a new three-part model for turbidity current behaviour: 1) flows begin as thin, high-concentration highly energetic flows; 2) the flows become more dilute with an expanding head; and 3) the flow rapidly thickens along its length. This new model of turbidity current behaviour, along with understanding the frequency of these events, explains the distribution of benthic communities in Monterey Canyon based on the biogenic sedimentary structures identified within the sedimentary cores.

Sedimentary organic matter contains many compounds that have no obvious biogenic precursors, so their formation and occurrence are of geochemical interest. The first part of this thesis (chapters 2-5) discusses the results obtained from studying hydrocarbon racemates. Some of the compounds identified are also suggested as intermediates in the formation of alkylnaphthalenes identified in chapters 6-7. The second part of this thesis (chapters 6-11) covers the identification of a range of alkylnaphthalenes and alkylphenanthrenes in sedimentary organic matter. Possible pathways for the formation of these hydrocarbons are outlined and their application as probes into the processes of petroleum formation are described.In chapter 2 the use of permethylated cyclodextrin capillary gas chromatography columns to separate hydrocarbon racemates are reported. Chapter 3 reports the synthesis of 1,2,2,5-tetramethyltetralin and 1,2,2,5,6-pentamethyltetralin and identifies them as racemates in crude oil. They are proposed as intermediates in the formation of sedimentary alkylnaphthalenes (identified in chapters 6 and 7).The identification of isodihydro-ar-curcumene in sedimentary organic matter is described in chapters 4 and 5. It co-occurs in crude oil with dihydro-ar-curcumene and is suggested to originate from this compound via a sedimentary rearrangement process. Chiral GC-MS techniques have been used to show the presence of both enantiomers of these compounds in crude oils. The elution order of the enantiomers has been established using reference compounds of known configuration. The effects of maturity and biodegradation on dihydro-ar-curcumene and isodihydro-ar-curcumene enantiomers is reported. Optically pure dihydro-ar-curcumene from natural products undergoes rapid racemisation in the subsurface, yielding a racemic mixture before the onset of significant oil formation. 1,2-Alkyl shifts on the aromatic ring also begin at an early stage to yield isodihydro-ar-curcumene and these processes continue with increasing maturity. Laboratory experiments using proton and clay catalysts (Lewis acid catalyst) show that the alkyl shift reaction is catalysed by both proton and Lewis acids, and racemisation is only catalysed by Lewis acids. A moderately biodegraded crude oil has been shown to be depleted in the R enantiomer of dihydro-ar-curcumene and an extensively degraded oil has dihydro-ar-curcumene depleted relative to isodihydro-ar-curcumene.The identification of a number alkylnaphthalenes and their possible origins in sedimentary organic matter is described in chapters 6 and 7. In chapter 6 a previously unreported tetramethylnaphthalene (TeMN) was identified in petroleum. This compound is structurally similar to bicyclic compounds of microbial origin and these are suggested as a likely source, via a tetralin intermediate identified in chapter 3. In chapter 7 isomeric pentamethylnaphthalenes previously unreported in sedimentary organic matter are reported. These isomeric pentamethylnaphthalenes (PMNs) were identified in a number of crude oils and sediments, ranging in age from Proterozoic to Tertiary. 1,2,3,5,6-PMN is suggested to form predominantly from the aromatisation of drimanoid precursors via 1,2,2,5,6-pentamethyltetralin identified in chapter 3. In laboratory experiments, the other pentamethylnaphthalenes were generated from 1,2,3,5,6-PMN in proportions that reflect the relative stability of the isomers. By analogy, the other PMNs in sediments are suggested to arise via acid catalysed isomerisation or transalkylation processes. A maturity parameter was developed based on laboratory experiments in conjunction with observed distributions of pentamethylnaphthalenes.The formation of alkylnaphthalenes and alkylphenanthrenes through a methylation process is discussed in chapters 8-10. Several crude oils and shales which contain anomalously high concentrations of 1,6-dimethylnaphthalene, 1,2,5-trimethylnaphthalene, 1,2,7-trimethylnaphthalene, 1,2,3,5-tetramethylnaphthalene, 1,2,3,5,6-pentamethylnaphthalene, 2-methyl-6-isopropyl-1(4-methylpentyl)naphthalene, phenanthrene, 1-methylphenanthrene, 1,7-dimethylphenanthrene and retene have been shown to contain relatively high concentrations of their corresponding methylated counterparts. In laboratory experiments carried out under mild conditions, each of the alkylnaphthalenes and alkylphenanthrenes have been shown to be methylated in specific positions when heated with a methyl donor in the presence of a clay catalyst. These observations have been interpreted as evidence for a sedimentary methylation process.The effect of biodegradation on alkylnaphthalenes and alkylphenanthrenes formed from sedimentary methylation is described in chapter 11. Land-plant-derived aromatic hydrocarbons with a range of susceptibilities to reservoir biodegradation have been identified in crude oils. These compounds are the result of reactions of natural products involving aromatisation, rearrangement and methylation in the sediments (chapters 9 and 10). They are therefore suggested as markers for land-plants in severely biodegraded oils in which most of the other biologically derived compounds cannot be recognised. The order of biodegradability of these compounds has been assessed relative to their non-methylated counterparts namely 6-isopropyl-2-methyl-1-(4-methylpentyl)naphthalene and retene. The order of degradation of the four compounds is : retene < 9-methylretene ~ 6-isopropyl-2-methyl-1-(4-methylpentyl)naphthalene > 6-isopropyl-2,4-dimethyl-1-(4-methylpentyl)naphthalene. These results have been used to assess that a crude oil is a mixture of severely biodegraded and less biodegraded crude oil.

Sedimentary organic matter contains many compounds that have no obvious biogenic precursors, so their formation and occurrence are of geochemical interest. The first part of this thesis (chapters 2-5) discusses the results obtained from studying hydrocarbon racemates. Some of the compounds identified are also suggested as intermediates in the formation of alkylnaphthalenes identified in chapters 6-7. The second part of this thesis (chapters 6-11) covers the identification of a range of alkylnaphthalenes and alkylphenanthrenes in sedimentary organic matter. Possible pathways for the formation of these hydrocarbons are outlined and their application as probes into the processes of petroleum formation are described.In chapter 2 the use of permethylated cyclodextrin capillary gas chromatography columns to separate hydrocarbon racemates are reported. Chapter 3 reports the synthesis of 1,2,2,5-tetramethyltetralin and 1,2,2,5,6-pentamethyltetralin and identifies them as racemates in crude oil. They are proposed as intermediates in the formation of sedimentary alkylnaphthalenes (identified in chapters 6 and 7).The identification of isodihydro-ar-curcumene in sedimentary organic matter is described in chapters 4 and 5. It co-occurs in crude oil with dihydro-ar-curcumene and is suggested to originate from this compound via a sedimentary rearrangement process. Chiral GC-MS techniques have been used to show the presence of both enantiomers of these compounds in crude oils. The elution order of the enantiomers has been established using reference compounds of known configuration. The effects of maturity and biodegradation on dihydro-ar-curcumene and isodihydro-ar-curcumene enantiomers is reported. Optically pure dihydro-ar-curcumene from natural products undergoes rapid racemisation in the subsurface, yielding a racemic mixture before the onset of significant oil formation. ++
1,2-Alkyl shifts on the aromatic ring also begin at an early stage to yield isodihydro-ar-curcumene and these processes continue with increasing maturity. Laboratory experiments using proton and clay catalysts (Lewis acid catalyst) show that the alkyl shift reaction is catalysed by both proton and Lewis acids, and racemisation is only catalysed by Lewis acids. A moderately biodegraded crude oil has been shown to be depleted in the R enantiomer of dihydro-ar-curcumene and an extensively degraded oil has dihydro-ar-curcumene depleted relative to isodihydro-ar-curcumene.The identification of a number alkylnaphthalenes and their possible origins in sedimentary organic matter is described in chapters 6 and 7. In chapter 6 a previously unreported tetramethylnaphthalene (TeMN) was identified in petroleum. This compound is structurally similar to bicyclic compounds of microbial origin and these are suggested as a likely source, via a tetralin intermediate identified in chapter 3. In chapter 7 isomeric pentamethylnaphthalenes previously unreported in sedimentary organic matter are reported. These isomeric pentamethylnaphthalenes (PMNs) were identified in a number of crude oils and sediments, ranging in age from Proterozoic to Tertiary. 1,2,3,5,6-PMN is suggested to form predominantly from the aromatisation of drimanoid precursors via 1,2,2,5,6-pentamethyltetralin identified in chapter 3. In laboratory experiments, the other pentamethylnaphthalenes were generated from 1,2,3,5,6-PMN in proportions that reflect the relative stability of the isomers. By analogy, the other PMNs in sediments are suggested to arise via acid catalysed isomerisation or transalkylation processes. A maturity parameter was developed based on laboratory experiments in conjunction with observed distributions of pentamethylnaphthalenes.The formation of alkylnaphthalenes and alkylphenanthrenes through a ++
methylation process is discussed in chapters 8-10. Several crude oils and shales which contain anomalously high concentrations of 1,6-dimethylnaphthalene, 1,2,5-trimethylnaphthalene, 1,2,7-trimethylnaphthalene, 1,2,3,5-tetramethylnaphthalene, 1,2,3,5,6-pentamethylnaphthalene, 2-methyl-6-isopropyl-1(4-methylpentyl)naphthalene, phenanthrene, 1-methylphenanthrene, 1,7-dimethylphenanthrene and retene have been shown to contain relatively high concentrations of their corresponding methylated counterparts. In laboratory experiments carried out under mild conditions, each of the alkylnaphthalenes and alkylphenanthrenes have been shown to be methylated in specific positions when heated with a methyl donor in the presence of a clay catalyst. These observations have been interpreted as evidence for a sedimentary methylation process.The effect of biodegradation on alkylnaphthalenes and alkylphenanthrenes formed from sedimentary methylation is described in chapter 11. Land-plant-derived aromatic hydrocarbons with a range of susceptibilities to reservoir biodegradation have been identified in crude oils. These compounds are the result of reactions of natural products involving aromatisation, rearrangement and methylation in the sediments (chapters 9 and 10). They are therefore suggested as markers for land-plants in severely biodegraded oils in which most of the other biologically derived compounds cannot be recognised. The order of biodegradability of these compounds has been assessed relative to their non-methylated counterparts namely 6-isopropyl-2-methyl-1-(4-methylpentyl)naphthalene and retene. The order of degradation of the four compounds is : retene < 9-methylretene ~ 6-isopropyl-2-methyl-1-(4-methylpentyl)naphthalene > 6-isopropyl-2,4-dimethyl-1-(4-methylpentyl)naphthalene. These results have been used to assess that a crude oil is a mixture of severely biodegraded and ++
less biodegraded crude oil.

A Formação Piauí registra a deposição de um sistema eólico, fluvial e marinho raso acumulado em uma bacia de sinéclise intracratônica. A caracterização das associações de fácies e do arcabouço estratigráfico foi feito através de uma descrição detalhada das fácies sedimentares e levantamento de perfis de afloramentos. As fácies foram classificadas de acordo com a textura dos grãos (tamanho e seleção) e estruturas sedimentares observadas. Medidas de paleocorrentes foram feitas nas estratificações e laminações cruzadas. Os perfis foram medidos na escala 1:50 em locais com boa exposição vertical. Seis associações de fácies foram reconhecidas, dunas e interdunas eólicas, lençóis de areia eólicos, canais fluviais, canais fluviais influenciados por maré, shoreface superior e shoreface inferior. Através da correlação das superfícies estratigráficas as associações de fácies foram organizadas em tratos de sistema, que formaram oito sequências deposicionais de alta frequência, delimitados por discordâncias subaéreas. Estas sequências são compostas por um trato de sistemas de nível baixo (TSNB), que é dominado por sistemas eólicos ou fluviais, um trato de sistemas transgressivo (TST), que é formado por canais fluviais influenciados por maré e/ou depósitos de shoreface superior e inferior com empilhamento retrogradacional, e um trato de sistemas de nível alto (TSNA), que é formado por depósitos de shoreface superior e inferior com empilhamento progradacional. Duas sequências deposicionais de mais baixa frequência foram determinadas ao observar o empilhamento das sequências de alta frequência. Ambas as sequências são formadas por uma regressão inicial seguida por uma transgressão progressiva. O principal controle das variações no nível relativo do mar durante a acumulação da Formação Piauí foi glacio-eustático. Contudo, mudanças climáticas estavam associadas com as fases glacio-eustáticas e influenciaram a deposição eólica e fluvial.
The Piauí Formation records the deposition of aeolian, fluvial and shallow marine systems accumulated in a cratonic sag basin. Characterization of the facies associations and sequence stratigraphic framework was done by detailed description of sedimentary facies and logging of outcrops. The facies were classified based on grain texture (size and selection) and sedimentary structures observed. Paleocurrent orientations were measured from cross-strata. Stratigraphic sections were measured at a 1:50 scale at outcrops with good vertical exposure. Six facies associations were recognized: aeolian dunes and interdunes, aeolian sandsheets, fluvial channels, tidally-influenced fluvial channels, upper shoreface and lower shoreface. Through correlation of stratigraphic surfaces the facies associations were organized in system tracts, which formed eight high frequency depositional sequences, bounded by subaerial unconformities. These sequences are composed of a lowstand system tract (LST), that is aeolian-dominated or fluvial-dominated, a transgressive system tract (TST) that is formed by tidally-influenced fluvial channels and/or upper and lower shoreface deposits with retrogradational stacking, and a highstand system tract (HST), which is formed by lower and upper shoreface deposits with progradational stacking. Two low frequency cycles were determined by observing the stacking of the high frequency cycles. Both sequences are formed by an initial regression followed by a progressive transgression. The main control on sedimentation in Piauí Formation was glacioeustasy, which was responsible for the changes in relative sea level. Even though, climate changes were associated with glacioeustatic phases and influenced the aeolian and fluvial deposition.

Sediments from 21 Oregon lakes were analyzed for seven metals (Fe, Mn, Zn, Cu, Co, Ni, V) in three forms (exchangeable, organic+sulfides, and oxyhydroxides+ oxides+ carbonates) using a sequential fractionation procedure. The summer epilimnetic filterable concentration of an eighth (Mo) was also determined. Sedimentary diatom remains and summer phytoplankton populations of the lakes were correlated with the 22 metal parameters and with conservative water chemistry parameters, estimators of lake productivity, and watershed geology. Both the sedimentary metals and the two populations of primary producers correlated best with the ecoregions of Omernik and Gallant (1986). A number of species possessed correlations with specific trace metal extractions or ratios of those extractions. Bloom-forming Anabaenas strongly correlated with sedimentary organic and filterable epilimnetic nickel. Possible Ni limitation of this group was observed in one Cascade lake (Lava). The ratio of organic nickel to cobalt appeared to control the abundance of several sedimentary diatoms. Organic vanadium strongly correlated with a number of diatoms, particularly in the genera, Cyclotella and Fragilaria. Possible V pollution was observed in one lake (Woahink), and frustule remains of C. stelligera significantly increased with increasing total sedimentary V concentrations there. Zinc was the trace metal most frequently found to apparently limit diatom growth. Diatoms may have developed three different responses to Zn limitation; the three groups have been labelled affinity-, velocity-, and (possibly) storage- specialists following Sommer (1985). Possible Zn pollution was observed in two lakes (Oswego and Clear). Phytoplankton and sedimentary diatoms weakly correlated with sedimentary iron by comparison to Ni, V, or Zn. Few strong relationships were observed with manganese, copper, or cobalt. No statistically significant correlations were found with molybdenum, and few correlations between a conservative chemical parameter and a species of phytoplankton were found. There was poor correlation between trace metal concentrations and lake productivity, despite frequently observed correlations between individual species and particular trace metal fractions. These findings suggest that variations in absolute trace metal concentrations, and/or ratios, may be important factors for controlling species distribution, but have relatively little influence upon lake primary productivity or standing stocks.

This project investigates the seismic response to facies variation by modelling facies variation itself, using two different modelling techniques, and then by modelling the seismic response to this variation. This study looks at a new set of attributes, examines their potential both as standard seismic attributes (a qualitative approach), and uses geostatistical analysis to further develop the ability of these attributes to differentiate the seismic response to facies variation. Sedpak, a basin modelling package was used to try to create facies models as a basis for further geophysical modelling. A case study using data from the Beryl area was unsuccessful at trying to create facies models due largely to the limited amount of input data and the scale of the models being attempted. Although an impressive package, Sedpak is most useful when modelling at a basin scale. In order to study the seismic response of sedimentary facies variation simple, deterministic models were set up using the geophysical modelling package, Gxii. An established methodology for analysing seismic data is the study of seismic attributes. The study considers some autocorrelation and power spectrum-derived functions previously described in the literature (Sinvhal and Sinvhal, 1992), and treats them as seismic attributes. Initial analysis of these new attributes in 2D showed them to be successful at detecting the presence of channels within seismic data. On the basis of this, a multivariate study was carried out. Results of this analysis show these attributes to have the potential to detect the presence of channels within seismic data. A suite of computer programs were developed to calculate 3D volumes of the new attributes, and to produce colour sections through the attribute volumes. The volumes were granted using a moving time window and calculating attribute values down through the data volume. Evaluation of the colour sections themselves to illustrate facies changes was disappointing. It is apparent that more work is needed to evaluate the window length over which the attributes are calculated.

This study aims to describe and quantify the important sedimentary processes which control the dispersal and accumulation of sediment in the Dwyryd Estuary, adjacent to Tremadog Bay in West Wales. It is shown that sedimentation in the estuary is dominantly control by fast tidal currents, and in the bay by weak tidal currents. Landward transport of coastal sediments by tidal currents is the residual sediment transport path. The spatial distribution of textural parameters of the estuarine sediments is related to the strength of tidal currents as well as the morphology and bathymetry of the study area. The estuarine sediments, predominantly sand, are very similar in texture and mineralogy to the adjacent beach sediments but markedly different to the river sediments. However, the beach sediments are slightly coarser and more poorly sorted than the estuarine sediments. In contrast, sediment in the deeper parts of Tremadog Bay are finer than both the estuarine and beach sediments due to the presence of substantial admixture of mud. The grain size distributions of most of the sediments are neither lognormal nor log-hyperbolic reflecting the great variability of hydrodynamic conditions in the study area. Using previously published flume data, a new sediment transport rate formula in the form of a power law has been developed for computation of total sediment load from the bed mean grain size and flow parameters: Uc The exponent n varies from 2.7 (for 0.93 mm sand) to 4.18 (for 0.19 mm sand). This is in contrast to the Bagnold (1966) formula which regards the exponent value (equal to 3) as constant for all grain sizes. Sediment transport patterns depend on the asymmetry between flood and ebb tidal currents due to distortion of the tidal wave on entering the estuary. Estimates of sediment budgets from surveyed profiles suggest that large amounts of sand have been transported from coastal areas into the estuary, supporting the mineralogical evidence. The estimates are of the same order of magnitude as estimates using flow velocity data and the above sediment transport formula.

Tethyan suture zones commonly undergo a change from compression to extension shortly after suturing. The mechanics and timing of this change in tectonic regime are poorly understood, and the extensional sedimentary basins of west Turkey, and , in particular, the northern Menderes massif, provide an excellent natural laboratory for the study of the crustal response to these different processes. During this study, field observations of sedimentary, structural and lithological features of the Alasehir Graben, Gördes and Selendi Basins, and their surroundings were combined with new radiometric age data to investigate the onset of N/S crustal extension in west Turkey. This timing of initiation has major implications for the driving mechanism of extension, since alternative models are time dependant. Extension driven by tectonic escape of west Anatolia requires extension to have begun in the Late Miocene, whilst extension driven by orogenic collapse of thickened crust in the region, and extension related to subduction roll-back both are postulated to have commenced in the Early Miocene. Extension in the northern Menderes massif took place on large-scale, presently low-angle (<20°), north-dipping normal (detachment) faults. Two separate detachment basin systems are recognised in the study area. The Gördes and Selendi Basins both trend NE/SW and formed by extension on the same northerly detachment system. This detachment has a strongly corrugated morphology when viewed parallel to extension, with a wavelength of ~30 km and an amplitude of ~1.5 km. The corrugations form the eastern and western margins of the Gördes and Selendi Basins and have produced 'scoop-shaped' depocentres and their characteristic NE/SW basin trend. No upper plate metamorphic lithologies are exposed within the basins and the total extension on the detachment fault system is in excess of 60 km. Syn-extensional sedimentation in the form of coarse alluvial fan conglomerates were deposited from south to north, and subsequently back rotated and tectonically emplaced against the detachment as a result of continuing extension. The initial sediments were followed by northward transported, braided-fluvial to alluvial-plain sandstones and conglomerates. These sediments unconformably overlie the syn-extensional deposits and passively onlap the basin margins.

The detailed 3D hydrogeological modelling of sedimentary media that form important aquifers is very complex because of: (1) the natural intrinsic heterogeneity of the geological media, (2) the need for integrating reliable 3D geological models that represent this heterogeneity in the hydrogeological modelling process and (3) the scarcity of comprenhensive tools for the systematic management of spatial and temporal dependent data. The first aim of this thesis was the development of a software platform to facilitate the creation of 3D hydrogeological models in sedimentary media. It is composed of a hydrogeological geospatial database and several sets of instruments working within a GIS environment. They were designed to manage, visualise, analyse, interpret and pre and post-process the data stored in the spatial database. The geospatial database (HYDOR) is based on the Personal Geodatabase structure of ArcGIS(ESRI) and enables the user to integrate into a logical and consistent structure the wide range of spatio-temporal dependent groundwater information from different sources and different formats. A set of applications in the database were established to facilitate and ensure the correct data entry in accordance with existing international standards. The set of analysis tools was developed as an extension of ArcMap environment (ArcGIS).This set of tools was separated into three main modules represented by different toolbars. The first toolbar, termed HEROS, allows the user to exploit the geological data stored in the database and facilitate the generation of 3D geological models. Detailed stratigraphic columns of the selected boreholes can be generated using customized queries. The automatic creation of a geological profile is possible by displaying the borehole lithological columns, the geophysical and geotechnical field-test results, and the defined stratigraphic units.The second toolbar, which is known as QUIMET, is composed of a set of instruments for analysis that cover a wide range of methodologies for querying, interpreting and comparing groundwater quality parameters. They include, among others, chemical time-series analysis, ionic balance calculations, correlation of chemical parameters, and calculation of various common hydrogeochemical diagrams. Moreover, it is also possible to perform a complete statistical analysis of the data including descriptive statistical univariate and bivariate analyses.The last toolbar (HYYH) was designed to analyse and visualise different hydrogeological measurements and hydraulic field test results. Contour maps and further spatial operations of the depth or thickness of the aquifers could be generated using customized queries. Likewise, piezometric maps can be created for the selected points and for the selected period of time with another command included in this toolbar. Additionally, multi-criteria query forms enable the user to analyse and visualise different data and interpretations derived from hydraulic tests. The interpreted data and calculations can be easily stored and consulted in the same platform and can be used to build an updatable model database for further interpretations. Thus, each new study does not have to start from scratch. The second aim of this thesis is to implement this modelling platform in the urban area of Barcelona (NE, Spain) to structure all the available data and to set up a working framework of groundwater resources in terms of both quantity and quality. Concretely, in the Besòs Delta area (NE Barcelona), the integration of the available data into the HYDOR database and the use of the aforementioned instruments and methods allowed us to: 1) delimit the geological units by means of sequence stratigraphic subdivision, 2) generate the 3D facies belt-based model of the Delta built on the basis of this geological characterisation and 3) use this model to constrain the distribution of hydraulic parameters and thus obtain a consistent hydrogeological model.
La modelización hidrogeológica tridimensional de los medios sedimentarios (p.ej. sedimentos aluviales, deltas) que suelen constituir acuíferos importantes es compleja debido principalmente a tres factores: (1) la heterogeneidad natural intrínseca del medio, (2) la necesidad de integrar un modelo geológico tridimensional que represente dicha heterogeneidad adecuadamente en los procesos de modelización hidrogeológica y (3) la escasez de herramientas apropiadas para gestionar grandes cantidades de datos hidrogeológicos espacio- temporales. El primer objetivo de esta tesis ha sido el desarrollo de una plataforma software en un entorno GIS que facilite la realización de modelos hidrogeológicos 3D. Está compuesta por una base de datos geoespacial y un conjunto de herramientas que permiten al usuario gestionar, visualizar, analizar, interpretar y pre-post procesar los datos almacenados en dicha base de datos. El modelo de bases de datos propuesta en esta tesis (HYDOR) se ha implementado en una base de datos geoespacial del tipo Personal Geodatabase (ArcGIS, ESRI) y permite la integración en una estructura coherente y lógica de un amplio rango de tipos de información hidrogeológica procedentes de diversas fuentes y con diferentes formatos. Los diferentes instrumentos desarrollados para explotar los datos almacenados en la base de datos se han creado como una extensión de ArcMap (ArcGIS; ESRI) y se reagrupan formando tres barras de herramientas. La primera barra de herramientas (HEROS) además de facilitarnos el análisis y la interpretación de los datos geológicos almacenados en la base de datos, nos permite generar modelos geológicos tridimensionales. Entre las funciones de dichas herramientas, está la de poder visualizar la información geológica aportada por los sondeos en forma de columna estratigráfica así como la generación automática de perfiles geológicos que muestran las diferentes columnas estratigráficas de los sondeos seleccionados. Información útil como los resultados de los ensayos geofísicos así como las unidades geológicas definidas aparecen también en la pantalla del mismo perfil geológico. Este entorno es óptimo para que el usuario analice y defina las superficies de correlación, las diferentes unidades geológicas y las posibles fallas. Estos elementos espaciales se pueden visualizar en tres dimensiones. Finalmente, otra herramienta nos proporciona la parametrización hidráulica inicial (para el modelo hidrogeológico) de las diferentes unidades geológicas partiendo de las características texturales de las mismas. La segunda barra de herramientas, QUIMET, cubre un amplio rango de metodologías para consultar, interpretar y comparar diferentes parámetros hidroquímicos. Además nos permite desarrollar un análisis estadístico completo en el que se incluyen entre otros, análisis estadísticos univariante, bivariante y generación de matrices de correlación de diferentes compuestos químicos. La última barra de herramientas (HYYH) se ha diseñado para visualizar y analizar los datos hidrogeológicos entre los que se incluyen los procedentes de ensayos hidráulicos. Usando estas herramientas se pueden generar mapas de isolineas y otras representaciones espaciales que nos permitan visualizar la profundidad o el espesor de los acuíferos. Del mismo modo, se pueden obtener mapas piezometricos de los puntos seleccionados para un intervalo de tiempo determinado por el usuario. Finalmente, otra herramienta nos permite consultar las interpretaciones procedentes de ensayos hidráulicos. La información obtenida usando todas estas herramientas, también se almacenan en la base de datos constituyendo de este modo una base para futuras interpretaciones. El segundo objetivo de esta tesis ha sido la aplicación de esta plataforma software en la gestión de los datos disponibles del área urbana de Barcelona (NE de España) obteniendo con ello una herramienta apropiada de gestión de los recursos hídricos de esta zona tanto en términos de calidad como de cantidad. Concretamente en la zona del Delta del Besòs (NE de Barcelona), la aplicación de esta plataforma de gestión nos ha facilitado lo siguiente: (1) la delimitación de unidades geológicas basadas en criterios de estratigrafía secuencial, (2) la generación de un modelo geológico tridimensional de facies basado en dichos criterios estratigráficos, (3) el uso del modelo geológico obtenido par establecer la distribución espacial de los parámetros hidráulicos que nos han servido para generar un modelo hidrogeológico consistenete del complejo deltaico. Este modelo se ha calibrado además con datos incluidos también en la base de datos y que proceden de diversos puntos tanto de gestión como de producción durante de los últimos 100 años. Todo esto ha supuesto una mejora significativa en la caracterización geológica del Delta del Besòs lo que nos ha llevado a mejorar su caracterización hidrogeológica.
La modelització hidrogeològica tridimensional dels mitjans sedimentaris que solen constituir aqüífers importants (p.ex. sediments al·luvials, deltes) és complexa. Això es deu principalment a tres factors: (1) l'heterogeneïtat natural intrínseca del medi, (2) la necessitat d'integrar un model geològic tridimensional que representi adequadament l’heterogeneïtat en els processos de modelització hidrogeològica i (3) l'escassetat d'eines apropiades per gestionar grans quantitats de dades hidrogeològiques espai-temporals. El primer objectiu d'aquesta tesi ha estat el desenvolupament d'una plataforma software en un entorn GIS que faciliti la realització de models hidrogeològics 3D. Està composta per una base de dades geoespacial i un conjunt d'eines que permeten que l’usuari gestioni, visualitzar, analitzi, interpreti i pre-post processi les dades emmagatzemades en la base de dades. El model de bases de dades proposada en aquesta tesi (HYDOR) s'ha implementat en una base de dades geoespacial de tipus Personal Geodatabase (ArcGIS , ESRI), que permet la integració d'un ampli rang de tipus d'informació hidrogeològica procedents de diverses fonts i formats en una estructura coherent i lògica. Les diferents eines desenvolupades per l’explotació de les dades emmagatzemades a la base de dades s'han implementat com una extensió d’ArcMap (ESRI). Aquestes eines es reagrupen en tres barres diferents. La primera barra d'eines, HEROS, ens permet analitzar i interpretar les dades geològiques emmagatzemades a la base de dades, permetent alhora la creació de models geològics tridimensionals. També s'han desenvolupat eines que permeten visualitzar la informació geològica aportada pels sondejos en forma de columna estratigràfica, així com generar automàticament perfils geològics per mostrar diferents columnes estratigràfiques de sondejos preseleccionats. A la pantalla del mateix perfil geològic també apareix informació útil com són els resultats dels assaigs geofísics o les unitats geològiques definides. Aquest entorn és òptim perquè l'usuari analitzi i defineixi les superfícies de correlació, les diferents unitats geològiques i les possibles falles. Els elements espacials definits es poden visualitzar en tres dimensions. Finalment, una altra eina ens proporciona la parametrització hidràulica inicial de les diferents unitats geològiques (per al model hidrogeològic) partint de les seves característiques texturals. La segona barra d' eines, QUIMET, inclou un ampli rang de metodologies de consulta, interpretació i comparació de diferents paràmetres hidroquímics. A més a més, també ens permet desenvolupar un anàlisi estadístic complet en el que s'inclouen, entre altres, anàlisis estadístics univariant, bivariant i generació de matrius de correlació de diferents compostos químics. L'última barra d' eines, HYYH, s'ha dissenyat per a visualitzar i analitzar les dades hidrogeològiques, entre d’altres, els procedents d'assajos hidràulics. Amb aquestes eines es poden generar mapes d'isolínies i altres representacions espacials que permeten visualitzar la profunditat o l'espessor dels aqüífers. De la mateixa manera, es poden obtenir mapes piezomètrics per a un interval de temps i de punts determinats per l'usuari. Finalment, una altra eina ens permet consultar les interpretacions procedents d'assajos hidràulics. La informació obtinguda de totes aquestes eines s'emmagatzema a la base de dades, constituint d'aquesta manera una base per a futures interpretacions. El segon objectiu d'aquesta tesi és l'aplicació d'aquesta plataforma software a la gestió de les dades disponibles de l'àrea urbana de Barcelona (NE de Espanya), obtenint una apropiada eina de gestió dels recursos hídrics d’aquesta zona, tant en termes de qualitat com de quantitat. Concretament a la zona del Delta del Besòs (NE de Barcelona), l'aplicació d'aquesta plataforma de gestió ens ha facilitat (1) la delimitació d'unitats geològiques basades en criteris d’estratigrafia seqüencial, (2) la generació d'un model geològic tridimensional de fàcies basat en aquests criteris estratigràfics i (3) l'ús del model geològic obtingut per a establir la distribució espacial dels paràmetres hidràulics que ens han servit per generar un model hidrogeològic consistenet del complex deltaic. Aquest model s'ha calibrat amb dades incloses a la base de dades i que procedeixen de diversos punts, tant de gestió com de producció, durant els últims 100 anys. Tot això ha suposat una millora significativa de la caracterització geològica del Delta del Besòs, el que ens ha portat a millorar la seva caracterització hidrogeològica.

The starting point for this Dr. Ing. thesis was the requirement for models describing basin scale overpressure for use in basin modelling studies. It is necessary to identify, understand and describe both the generating mechanisms and the fluid flow in sedimentary basins in order to meet this requirement.

All of the models developed are based upon a study area consisting of fault bounded pressure compartments. A reservoir simulator has applied a lateral cross fault transmissibility model and by defining the overpressure history in some of the pressure compartments it has been possible to model the overpressure through geological time. A simpler model estimating the present day overpressure distribution based upon the same fault transmissibility model is developed. This model is able to provide a snapshot of the main present day pressure trends. This model has further been developed to a full pseudo 3D-pressure simulator including generation and dissipation of pressure through time. Due to the quantification of generation and dissipation of overpressure it is possible to model hydraulic fracturing and leakage through the overlying seals. In addition to the models describing the overpressure, an algorithm that converts the pressure compartments into a quadrangle grid system is developed.

The main part of the work in this thesis deals with quantifying basin scale generation and dissipation of overpressure. Different models are developed based upon the available literature and knowledge achieved during this work. All the models used are thoroughly described. The pressure simulator PRESSIM is developed in order to test, improve and reject different models. Several simulations of the overpressure history in the North Viking Graben and the Haltenbanken area offshore Norway are presented. The modelled overpressures are calibrated to the observed pressures revealed by exploration wells. In general, the results are very satisfactory due to relatively small deviations between the modelled and observed overpressures. The simulations provide an increased knowledge of the mechanisms generating and dissipating the overpressure and form a good basis for discussing the nature of the overpressure. In addition, the results suggest which mechanisms are the most important in the different parts of the basin. The pressure simulator PRESSIM can be used to test and verify alternative pressure generation models and flow descriptions in a basin. It is possible to model the position and timing of the hydraulic fracturing because the pressure simulations are based upon a water budget for each pressure compartment.

Remote sensing has transformed coral reef science in the last decades. It is now possible to audit reef health and geomorphology at global scale and very high spatial resolution. This work utilizes the vast and no-cost archive of imagery housed within Google Earth (GE). GE was used to interrogate the morphometric properties (size, shape, complexity, etc) of the components that combine to yield a reef environment (reef structures, sediment sheets, and so forth). The data populated a morphometric database for reefs globally that are partitioned by their architecture. The database has been investigated using information theory. The aim of the work is to identify whether motifs of carbonate platforms within these reef types are predictable on the basis of environmental parameters. The results are relevant to assess depositional patterns to develop rules for predicting how facies are distributed in modern systems and ancient reservoirs.

The record of climate change in Signedalen and Krossfjorden, northwest Spitsbergen, since the Late Weichselian glacial maximum, has been constructed using an integrated analysis of lacustrine, terrestrial and marine sediments. Thirty-four piston cores were taken from two series of linked lakes in Signedalen, fed by three small cirque glaciers. Six further cores were taken from the fjord inlet, Signehamna, into which meltwater from the linked glacier-fed lakes and a further two glaciers drain. Signehamna drains into Lilliehookfjorden, which with Mollerfjorden, combines to form Krossfjorden, from which 16 .cores were made available. Cores were analysed for moisture content, loss-on-ignition, bulk density, grain size, magnetic susceptibility, infra-red stimulated luminescence, by X-radiography and by radioisotopic dating methods, 210Pb and 14C. Bathymetric maps were constructed following echo sounding survey of the lakes. Seventy-two water samples from the linked lakes were used to assess contemporary environmental conditions, and to aid interpretation of sedimentary structures within core sediments. Results of lichenometric survey of moraine ridges and pro-talus deposits in and around Signedalen were analysed using discriminant analysis, and compared with Werner's (1988) lichen growth curve in order to establish a chronology of moraine stabilisation. Seismic records of Krossfjorden have revealed evidence of glacier advance at least as far as the sill separating Krossfjorden from the outer parts of the fjord and shelf associated with the Late Weichselian glacial maximum (Sexton et al., in press). Overlying the basal unit of a possible till , or sediments associated with rapid glacier retreat, is a blanket of homogeneous sediment formed by ice-distal deposition during the Holocene. There is no evidence of Younger Dryas glacier expansion preserved in the marine sediments, or in terrestrial moraines. Denudation rates calculated from lacustrine sediment accumulation infer the presence of smaller glaciers in Signedalen during the Younger Dryas than at present. The early to mid Holocene appears to have been characterised by relatively warm conditions, with much reduced glacier presence in Signedalen. Evidence of Neoglacial cooling, between approximately 3,000 yr BP and 1,500 yr BP, is found in lichenometric recorckof talus deposits, although precise dating of the inception, and duration of this cooling is problematic. No moraine sediments are recorded from this period. The Little Ice Age maximum, dated by licheno~etry to AD 1890, was the most extensive glacier advance to have affected the cirque glaciers of Signedalen and the tidewater glaciers of Krossfjorden, and is associated with the highest denudation rates recorded in the lacustrine sediments. It also appears to have been responsible for the formation of rock glaciers within the protalus deposits of Signedalen. Since this date, a general retreat of glaciers has been interrupted periodically by still-stands or slight readvances when climatic conditions deteriorated.

The response of salt marshes to sea level rise is dependent upon the availability of an adequate sediment supply and the subsequent rate of accretion of sediment on the salt marsh surface. On the north Sefton coast, the geomorphology and sedimentology of the area has resulted in the continued expansion of salt marsh within the outer reaches of the Ribble Estuary, enhanced by human activities over the last 200 years. The area has undergone significant human alteration in that time.

This paper presents PDEs that describes sedimentation by a system of diffusion and transportation equations. These PDEs are implemented with a semi-implicit scheme and solved on a Graphics Processing Unit (GPU). The equations are solved with the iterative solvers (conjugate gradient and biconjugate gradient stabilized method) provided by the software ViennaCL. The timings from these operations are compared with a CPU implementation. Before using the iterative solvers, a sparse matrix and a right hand side vector is set. The sparse matrix and the right hand side vector are efficiently updated on the GPU. The implicit terms of the PDEs are stored in the sparse matrix and the explicit terms in the right hand side vector. The sparse matrix is stored in the compressed sparse row (CSR) format. Algorithms to update the sparse matrix for the PDEs, which have Neumann or a mix of Neumann and Dirichlet boundary conditions, are presented. As the values in the sparse matrix depend on values from the previous results, the sparse matrix has to be updated frequently. Considerable time is saved by updating the sparse matrix on the GPU instead of on the CPU (slow data transfers between CPU and GPU are reduced). The speedup for the GPU implementation was found to be 8-10 and 12-18 for the GPUs GTX 590 and K20m respectively, depending on grid size. The high speedup is due to the CPU model of the CPUs used for timings being an older model. If a newer CPU model were used, the speedup would be lower. Due to limited access to newer hardware, a more accurate value for speedup comparison has not been acquired. Indications still prove that the GPU implementation is faster than the sequential CPU implementation.
Den här uppsatsen presenterar PDEer som beskriver sedimentering av ett system av diffusion och transport ekvationer. Dessa PDEerna blir implementerade med en halvimplicit metod och löst med en grafikprocessor (GPU). Ekvationerna är lösta med iterativa lösare (CG och BiCGStab) från mjukvaran ViennaCL. Tidsmätningarna från dessa operationerna blir jämförda med en CPU-implementation. För användandet av de iterativa lösarna blir en gles matris och en vektor på höger sida satt. Den glesa matrisen och vektorn blir effektivt uppdaterat av GPUen. De implicita termerna blir lagrat i den glesa matrisen och de explicita termerna i vektorn på höger sida. Den glesa matrisen är sparat i det komprimerade glesa rad (CSR) formatet. Algoritmer för att uppdatera den glesa matrisen för PDEs som har Neumann, eller Neumann och Dirichlet randvillkor blir presenterade. Eftersom värdena i den glesa matrisen beror på värdena från det förra resultatet, måste den glesa matrisen uppdateras ofta. Avsevärt med tid sparas av att uppdatera den glesa matrisen på GPUen istället för på CPUen (långsamma data överföringar mellan CPU och GPU reduceras). Accelerationen för GPU-implementationen konstaterades vara 8-10 och 12-18 för GPUena GTX 590 och K20m beroende på storleken på rutnätet. Den höga accelerationen beror på att CPU-modellen som användes till tidmätning är en äldre modell. Om en nyare CPU modell användes, ville accelerationen bli lägre. På grund av begränsad tillgång till nyare hårdvara, har inte mer exakta värden för acceleration kunnat uppdrivas. Indikationer visar dock att GPU-implementationen är snabbare än den sekventiella CPU-implementationen.

Safety, optimisation and the sustainability are the most important aspects for the design of any foundation system. An optimised and safe design of foundation systems for high-rise structures in difficult soil and groundwater conditions is based on a reduction of construction material used, construction time spent, energy consumed and the adequate consideration of the soil-structure interaction. This is also important for the high-rise structures like skyscrapers and bridge piers in Dubai, UAE. Due to the large loads most of these structures are founded in the Dubai sedimentary rock. Up to now the rock mechanical parameters for these rock layers have been defined on the very conservative side which led to over-dimensioned foundations in many cases. In a large research program the bearing behaviour of Dubai Sandstone and Dubai Siltstone has been investigated by field and laboratory tests, by in-situ pile load tests and the numerical back-analysis using the Finite-Element-Method (FEM). The comprehensive research investigations show, that the stiffness and strength of Dubai sedimentary rock is more than 20 times higher as it is assumed up to now. The thesis presents the scope of research, the epoch-making results and the significance for the engineering practice. The geotechnical data used in this thesis is collected from geotechnical investigation reports (195 boreholes) and static load tests (116) from more than 45 towers in Business Bay and Downtown Dubai as well as a case study evaluating one project located in Business Bay.

Il significato del materiale vulcaniclastico in bacini ricchi in sequence torbiditiche sembra essere assodato ed ambiguo nello stesso tempo. Il problema si pone quando il sistema area sorgente-bacino depositionale non risulta perfettamente preservato e/o differenti cicli magmatici sono registrati nel record stratigrafico, e risulta pragmaticamente difficile interpretare il segnale vulcaniclastico. Il problema principale riguarda discriminare la produzione di sedimento sin-magmatica da quella post-magmatica, tettonicamente controllata, nei depositi distali. In questo lavoro abbiamo preso in considerazione cinque formazioni esposte tra il bacino Giurassico continentale chiamato Cañadón Asfalto basin (Provincia del Chubut, Argentina), il bacino oligocenico degli Appennini settentrionali (Val d'Aveto, Piacenza – Italia), la Molassa Oligocenica Alpina (Francia e Svizzera) e l'avanfossa oligocenica alpina (Como – Italia). Le Formazioni considerate sono Las Leoneras e Lonco Trapial (Argentina), la Formazione della Val d'Aveto Formation (Appennini), le arenarie di Taveyanne (Francia e Svizzera) ed il Conglomerato di Villa Olmo (Como). Si è portato avanti un lavoro di terreno atto a misurare le colonne stratigrafiche nei bacini, effettuare il conteggio litologico dei clasti su conglomerati, correlare i depositi e ricostruirne le geometrie deposizionali. Più di 150 campioni sono stati selezionati tra strati arenitici e pelitici, clasti ignei, metamorfici e sedimentari, i quali sono stati tagliati per sezioni sottili, osservati al microscopio, analizzati mineralogicamente (diffrazione raggi X) e chimicamente (fluorescenza), minero-chimicamente tramite SEM-EDS e paleomagneticamente, in modo da ottenere qualsiasi tipo di indizio di attività sin-vulcanica della zona. Quando sono stati riconosciuti, depositi di flusso piroclastici primari preservati sott'acqua sono stati inoltre approfonditamente caratterizzati, per definire i possibili meccanismi che ne permettono la preservazione al passaggio aria/acqua. Le arenarie sono state composizionalmente analizzate tramite i metodi Folk e/o Gazzi-Dickinson, oppure tramite analisi XRD se di grana troppo minuta. La petrografia dei clasti ignei, sedimentari e metamorfici è stata utilizzata per studi di provenienza del detrito. Tutti i dati sono stati correlati a livello regionale prima, generale poi per considerazioni geodinamiche e sedimentologiche. Come mostrato nella tesi, il vulcanismo risulta dare vita ad un segnale molto forte, il quale cannibalizza il record stratigrafico, ma di breve durata, essendo legato all'attività dei centri vulcanici (media della vita 1 milione di anni). Il segnale tettonico, invece, pur avendo un impatto minore rispetto a quello vulcanico sul breve termine, è più duraturo ed ampio.

A change in fluvial style and a change in the stacking pattern of fluvial channel sandstone bodies occur across the Buckley□Fremouw formational contact in the central Transantarctic Mountains in Antarctica. Strata in the Buckley Formation are characterized by thick floodplain deposits in the Middle to Upper Permian Buckley Formation; whereas, stacked interconnected sandstone bodies occur in the Triassic Fremouw Formation (Barrett et al., 1986; Isbell & Macdonald, 1991a, 1991b; Collinson et al., 1994; Isbell et al., 1997; 2005). Such changes in fluvial stacking patterns have been attributed to changes in the creation of accommodation within basins due to changes in relative sea level, changes in accommodation due to tectonism, and changes in sediment flux associated with loss of vegetation and increased erosion rates following the end-Permian mass extinction event. To explain the changes in the Buckley-Fremouw Formation in Antarctica, Isbell & Macdonald (1991a, 1991b) and Isbell et al. (1997) argued for changing tectonic conditions in the basin while Retallack et al. (2006) suggested the changes were associated with the P□T mass extinction event causing the loss of peat forming plants. This study found that the change in the accommodation across the PTB was a result of tectonism based on evidence of changing sandstone composition, changing paleocurrent orientations, and changing fluvial stacking patterns between the Buckley Formation and the Fremouw Formation. This suggests differential subsidence in the Transantarctic foreland basin with an under-filled basin in the Late Permian changing to an over-filled basin in the Early Triassic.

In this dissertation, a fully depth-dependent 2D kinematic model of the litho­sphere is developed. This forward model forms the basis of an inversion scheme capable of recovering the temporal and spatial strain rate history of a basin from present-day observed stratigraphic and subsidence data. The inversion scheme does not assume any a priori form for the strain rate distribution and unlike previous inversion schemes does not assume that the strain rate is invariant with depth (White and Bellingham, 2002). The depth-dependent inversion is applied to two sedimentary basins. Data from the Northern North Sea is used to benchmark the new code against the previous 2D inversion scheme and the Gulf of Suez is studied in detail using newly collated stratigraphic profiles from across the region. The Gulf of Suez is found to have stretched by 12-18 km in two rift phases at 23-18 Ma and 14-11 Ma. Depth­-dependent stretching appears to be more important in the Southern Gulf than in the north. In the south, stretching factors beneath uplifted regions are higher in the mantle than in the crust. Data from three passive margins is also inverted. The inversion scheme provides little evidence for depth-dependent stretching in the Eastern Black Sea. However, the stratigraphic data from the Pearl River Mouth basin and Angolan Margin can be more faithfully reproduced when depth-dependent effects are included. In all cases, recovered strain rates and timings of rift events are consistent with published values. Using the inversion scheme developed within this dissertation allowed results to be obtained with no a priori assumptions about the form or timing of the rifting periods.

Integrated analysis of whole-rock and mineral geochemical data from black shale and metamorphosed black shale demonstrates the importance of sulfides as trace-element hosts and reveals the influence of depositional environment on whole-rock and mineral chemistries. Detailed analysis of Fe-sulfide contents provides evidence of considerable elemental redistribution during diagenesis and metamorphism, indicating that such sulfides plausibly serve as a source of metals and other elements to epigenetic fluids. Spatial and temporal analysis of the distribution of Phanerozoic black shale, phosphorite, and ironstone suggests a related geologic origin coupled to marine upwelling. Organic-rich sedimentary rocks from diverse geologic settings in China, Canada, US Great Basin, and US Mid-Continent were studied along with regionally metamorphosed black shale (Maine) and contact metamorphosed carbonaceous argillite (Nevada). Assessment of whole-rock geochemistry in these samples was supplemented with analysis of a large geochemical database compiled from published sources. Both the studied sample suite and literature database reveal systematic elemental enrichments and depletions that can be related to depositional environment. Regionally metamorphosed black shale demonstrates trace-element loss with metamorphism (Au, As, and Sb), an observation that fits well with models proposing black-shale-derived mineralizing fluids. Compositional and textural features of sedimentary and metamorphic sulfides were investigated utilizing petrographic and in situ analysis methods. Concentrations of As, Se, Ni, Co, Cu, Zn, V, Cr, and Mo in sulfides were acquired by electron microprobe. Au, Pt, and sulfur isotope contents were measured in Fe-sulfide by SIMS. Fe-sulfide data demonstrate a complex history of pyrite growth due to diagenetic, metamorphic and hydrothermal processes. Sulfur isotopes reflect bacterially mediated growth of framboidal pyrite and redistribution of this sulfur with advanced diagenesis and metamorphism. Early framboidal pyrites are enriched in many trace metals. Later diagenetic and metamorphic pyrites are typically lower in trace metal content and demonstrate recrystallization to coarser crystals. Comparison of trace elements in framboidal and coarse overgrowth pyrites shows systematic elemental changes (losses: Au, Pt, Ni, Cu, Zn, V and Cr; gains: Se; variable: As and Mo). This pattern is found in many black shales, regardless of bulk chemistry or depositional environment. Metamorphic replacement of pyrite by pyrrhotite results in similar losses from the sulfide fraction of the rock. Mass balance of the whole-rock trace inventory indicates that Fe-sulfide is an important host for As, Se, Ni, Co, and Au. These mass balance results, combined with evidence of trace element redistribution during diagenesis and metamorphism, point to a possible sourcing of metals, sulfur and other elements from black shale.

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Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (ANP)
A Formação Rio Bonito é a unidade inferior do Grupo Guatá, Eopermiana da Bacia do Paraná. Compreende, da base para o topo, os membros Triunfo, Paraguaçu e Siderópolis. No Estado do Paraná, a espessura da Formação Rio Bonito diminui para norte, principalmente em conseqüência do adelgaçamento e acunhamento do Membro Triunfo, que desaparece no sul do Estado de São Paulo. Para investigar estas variações de espessura e de fácies na Formação Rio Bonito, foi escolhida uma área no nordeste do Estado do Paraná onde a unidade apresenta bons afloramentos e poços para correlação, além de existirem importantes ocorrências de carvão. Para atingir os objetivos propostos, foram levantados perfis estratigráficos verticais e confeccionadas seções estratigráficas, levantados dados de paleocorrentes, caracterizadas associações de fácies sedimentares, correlacionados dados de superfície com os de perfis de poços, interpretados os paleoambientes de sedimentação e comparado o empilhamento estratigráfico da área estudada com o de áreas adjacentes. Cinco associações de fácies foram caracterizadas, permitindo constatar que a parte inferior da Formação Rio Bonito no nordeste do Estado do Paraná apresenta espessuras variáveis por ser o produto de preenchimento sedimentar uma sobre superfície deposicional irregular. Devido à existência de paleovales na superfície do topo do Grupo Itararé, de estruturas sedimentares produzidas por correntes de maré e de paleocorrentes bipolares para norte e sul, a parte inferior da Formação Rio Bonito foi interpretada como produto de preenchimento de vales incisos por depósitos aluviais e de canais de maré (associações de fácies 1 e 2, Membro Triunfo), sobrepostos retrogradacionalmente por lamitos e arenitos de canais de maré da zona central do estuário (associação de fácies 3)...
The Rio Bonito Formation is the lowermost unit of the Guatá Group, Early Permian of the Paraná Basin. It comprises from the bottom to the top, the Triunfo, Paraguaçu and Siderópolis Members. In the State of Paraná, the thickness of the Rio Bonito Formation decreases northwards, mainly because of the thinning and wedging out of the Triunfo Member, which disappears in the south of the State of São Paulo. To investigate thickness and facies variations in the Rio Bonito Formation, an area in the northeast of the State of Paraná was chosen wherein the unit presents good outcrops and wells for correlation, besides the existence of important coal beds. To reach the proposed objectives, vertical stratigraphic profiles and stratigraphic sections were made, paleocurrents data were obtainded, sedimentary facies were characterized, correlation between surface and well profile data were performed, sedimentation paleoenvironments were interpreted and the local stratigraphic succession correlated with adjacent areas. Five facies associations were characterized, being possible to observe that the thickness variations of the Rio Bonito Formation in the northeast of the State of Paraná resulted from sedimentation on an irregular depositional surface. Due to the existence of paleovalleys and the sedimentary structures produced by tide currents and bipolar paleocurrents towards the north and south, the lower portion of the Rio Bonito Formation was interpreted as a product of incised-valleys filled-up by estuarine alluvial and tidal channels deposits (facies associations 1 and 2, Triunfo Member). The succession is retrogradational and the basal section is overlayed by mudstones and sandstones of tidal-channels from the innermost portion of the estuary (facies association 3)...(Complete abstract click electronic access below)

I seek to reconstruct the balance between sediment storage and yield across multiple drainage basin scales in a large (1 230 km2) watershed in the Northern Cascade range, British Columbia and Washington. Chilliwack Valley and surrounding area has been the site of numerous studies that have detailed much of its Quaternary sedimentary history. In the present study this information is supplemented by reconstruction of the morphodynamic trajectory of the river valley though the Holocene Epoch, and development of a sediment transfer model that describes the relaxation from the Fraser glaciation. The total Holocene sediment yield is estimated from basins across several scales using field and remotely sensed evidence to constrain the historical mass balance of delivery to higher order tributary basins. Rates of hillslope erosion are estimated using a diffusion-based relation for open slopes and delimitating the volume evacuated from major gully sources. Digital terrain models of paleo-surfaces are constructed to calculate total sediment erosion and deposition from tributary valleys and the mainstem. Chilliwack Lake has effectively trapped the entire post-glacial sediment load from the upper catchment (area = 334 km2), allowing to compare this "nested" system with the larger catchment. Rates of lake sediment accumulation are estimated using sediment cores and paleomagnetism. These are compared with accumulation rates in the terminal fan inferred from radiocarbon dating of fossil material, obtained by sonic drilling in the apex gravels. A sediment budget framework is then used to summarize the net transfer of weathered material and glacial sediments from the hillslope scale to the mainstem. The long-term average sediment yield from the upper basin is 62 +/- 9 t/km2/yr; contemporary yield is approximately 30 t/km2/yr. It is found that only 10-15% of the material eroded from the hillslopes is delivered to mouths of the major tributaries; the remaining material is stored at the base of footslopes and within the fluvial sedimentary system. Since the retreat of Fraser Ice from the mouth of the valley, Chilliwack River delivered over 1.8 +/- 0.21 km3 of gravel and sand to Vedder Fan in the Fraser Valley. In the sediment budget developed here, roughly 85% of that material is attributed to glacial sources, notably the Ryder Uplands and glacial valley fills deposited along the mainstem, upstream of Tamihi Creek. In tributary valleys, local base-level has fallen, leading to the evacuation of deep glacial sedimentary fills. Many of the lower reaches of major tributaries in upper Chilliwack Valley (e.g. Centre and Nesakwatch Creeks) remain primarily sediment sinks for slope-derived inputs, since base-level fall has not been initiated. In distal tributaries (Liumchen, Tamihi and Slesse creeks), paraglacial fans have been incised or completely eroded, entrained by laterally active channels. A transition from transport-limited to supply-limited conditions has been effected in many of these reaches. Slesse Creek has struck an intermediate balance, as it continues to remobilize its considerable sediment stores. It functions today as the sedimentary headwaters of Chilliwack Valley. Using grain size data and fine-sediment geochemical data gathered from Chilliwack River over the course of several field seasons, a simple finite-difference, surface-based sediment transport model is proposed. The aim of the model is to integrate the sediment-balance information, as inferred from estimates of hillslope erosion and valley storage, and physical principles of sediment transport dynamics to reproduce the key characteristics of a system undergoing base-level fall and reworking its considerable valley fill during degradation. Such characteristics include the river long profile, the river grain-size fining gradient, the percentage of substrate sand, and the diminution of headwater granite lithology in the active load. The model is able to reproduce many of the characteristics, but is not able to satisfy all criteria simultaneously. There is inevitably some ambiguity as to the set of parameters that produce the "right" result, however the model provides good insight into long-term interactions among parameters such as dominant discharge, grain size specifications, abrasion rates, initial topography, hiding functions, and hydraulic parameters.

The Re-Os organic-rich sedimentary rocks (ORS) geochronometer has the potential to provide precise depositional ages and vital information on the Os isotope composition of palaeo-seawater. This thesis presents new geochronology data from Proterozoic sedimentary successions and insights into Re-Os systematics of organic-rich sedimentary rocks and petroleum products such as bitumen and oil. New Re-Os ORS geochronology from two drill cores indicate that the Proterozoic Atar Group of the Taoudeni basin, Mauritania is ~200 Ma older than previous estimates (1107 ± 12 Ma, 1109 ± 22 Ma and 1105 ± 37 Ma). Furthermore, this data also provides precise Re-Os geochronology data from sedimentary rocks that have experienced flash pyrolysis and demonstrate that the Re-Os systematics are not disturbed by the effects of very rapid heating. Coupled with palaeomagnetic data the Re-Os geochronology suggests that a reassessment of the role of the West African craton during the assembly of Rodinia is required. New Re-Os geochronology for the Ballachulish Slate Formation of the Dalradian Supergroup, Scotland yields a depositional age of 659.6 ± 9.6 Ma. The Re-Os age represents a maximum age for the glaciogenic Port Askaig Formation and represents the first successful application of the Re-Os geochronometer in sedimentary rocks with low Re and Os abundances (<1 ppb and <50 ppt, respectively). This new age suggests that the Port Askaig Formation may be correlative with Sturtian glaciations rather than middle Cryogenian events. Laboratory-based hydrous pyrolysis experiments were employed to evaluate the complexation of Re and Os in ORS and their transfer behaviour into petroleum. The findings from these experiments demonstrate that the Re-Os geochronometer is not disturbed by thermal maturation of whole rocks. Furthermore, the data support the hypothesis that the isotope composition of oils and bitumens can be used to fingerprint petroleum to specific source rocks.

This thesis uses forward modelling to investigate the formation of intercratonic basins upon accretionary crust. It began from the hypothesis that accretionary crust forms with a near normal thickness crust, but a thin lithosphere inherited from the terranes that compose it. After the accretion process has ceased the lithosphere stabilises and begins to cool, causing it to grow thicker and this in turn drives subsidence of the accretionary crust. A 1-D finite difference computer code was developed to model conductive heat flow through a column of cooling lithosphere and asthenosphere. To test the hypothesis, the subsidence produced by the modelling of this process was compared to the observed subsidence from backstripping numerous basins situated on accretionary crust The model produced a good fit to the subsidence in a detailed case study of two of the Palaeozoic basins in North Africa. The study was then extended to test the applicability of to accretionary crust globally. It found that while using measured values of the crust and lithospheric thickness for each region the model produced subsidence curves that matched the observed subsidence in each basin. It makes a more coherent argument for the formation of these basins that is able to explain a wider variety of features than other proposed subsidence mechanisms such as slow stretching or dynamic topography. These results suggest that such subsidence is an inherent property of accretionary crust which could influence the evolution of the continental crust over long time periods. The model was used to investigate the subsidence of the West Siberian Basin and found the subsidence patterns to be consistent with the decay of a plume head which thinned the lithosphere. This subsidence patterns indicate the plume material thinned the lithosphere over an area of 2.5 million km2 resulting in uplift before it cooled and subsided.

Sedimentary basins form when water-borne sediments in shallow seas are deposited over periods of millions of years. Sediments compact under their own weight, causing the expulsion of pore water. If this expulsion is sufficiently slow, overpressuring can result, a phenomenon which is of concern in oil drilling operations. The competition between pore water expulsion and burial is complicated by a variety of factors, which include diagenesis (clay dewatering), and different modes (elastic or viscous) of rheological deformation via compaction and pressure solution, which may also include hysteresis in the constitutive behaviours. This thesis is concerned with models which can describe the evolution of porosity and pore pressure in sedimentary basins. We begin by analysing the simplest case of poroelastic compaction which in a 1-D case results in a nonlinear diffusion equation, controlled principally by a dimensionless parameter lambda, which is the ratio of the hydraulic conductivity to the sedimentation rate. We provide analytic and numerical results for both large and small lambda in Chapter 3 and Chapter 4. We then put a more realistic rheological relation with hysteresis into the model and investigate its effects during loading and unloading in Chapter 5. A discontinuous porosity profile may occur if the unloaded system is reloaded. We pursue the model further by considering diagenesis as a dehydration model in Chapter 6, then we extend it to a more realistic dissolution-precipitation reaction-transport model in Chapter 7 by including most of the known physics and chemistry derived from experimental studies. We eventually derive a viscous compaction model for pressure solution in sedimentary basins in Chapter 8, and show how the model suggests radically different behaviours in the distinct limits of slow and fast compaction. When lambda << 1, compaction is limited to a basal boundary layer. When lambda >> 1, compaction occurs throughout the basin, and the basic equilibrium solution near the surface is a near parabolic profile of porosity. But it is only valid to a finite depth where the permeability has decreased sufficiently, and a transition occurs, marking a switch from a normally pressured environment to one with high pore pressures.