Evolution of submarine channel and lobe systems above dynamic stepped slopes

Submarine slopes with stepped profiles record sandy channel and lobe systems across depocentres and muddy bypass-prone ramps. The widely applied fill-and-spill model predicts the depositional architecture of stepped slope successions. However, this model implies a constant topographic configuration over the lifespan of a turbidite system. In contrast, the impact of dynamic slopes, with spatially variable topographic configurations, on patterns of erosion and deposition remains poorly investigated. This thesis aims to document deep-water sedimentation patterns above stepped slopes subject to active extensional salt tectonics using comprehensive subsurface datasets from the Campos Basin, offshore Brazil. Extensive seismic mapping and well correlation of two Oligocene-Miocene deep-water successions support the interpretation of large-scale structural controls on the configuration of depocentres, and relationships between seismic geomorphology, depositional architecture, thicknesses and stacking patterns, and lithology/facies distribution above a dynamic slope topography. In the Marlim Unit area, high-resolution stratigraphic models capture the impact of subtle lateral and basinward tilting, and fluctuations in the sediment supply, which result in complex stratigraphic patterns with multiple phases, and multiple entry and exit points. Furthermore, extreme variations in the thickness of buried channel-fills are documented for the first time, which are interpreted to record a transient uplift related to salt tectonics in an otherwise subsiding depocentre. In the Albacora depocentre area, salt structures reactivated by extension and contraction formed subtle seabed topography that defined the edges of the depocentre. An elongate depression, later filled by sand-prone turbidites, developed immediately after the emplacement of a regional-scale mass transport complex. This contrasts with the role of mass wasting processes in active salt basins, which are a product of slope deformation and not a cause. In summary, models of dynamic topographic deformation on the stratigraphic evolution of intraslope depocentres are developed, which can be applied to the extensional domains of salt basins globally

Tectônica e sedimentação na bacia do Paraná : um estudo de caso na região Charqueadas-Triunfo (RS) - fase 1: análise estratigráfica

26

Quantitative analysis of a footwall‐scarp degradation complex and syn‐rift stratigraphic architecture, Exmouth Plateau, NW Shelf, offshore Australia

Interactions between footwall‐, hangingwall‐ and axial‐derived depositional systems make syn‐rift stratigraphic architecture difficult to predict, and preservation of net‐erosional source landscapes is limited. Distinguishing between deposits derived from fault‐scarp degradation (consequent systems) and those derived from long‐lived catchments beyond the fault block crest (antecedent systems) is also challenging, but important for hydrocarbon reservoir prospecting. We undertake geometric and volumetric analysis of a fault‐scarp degradation complex and adjacent hangingwall‐fill associated with the Thebe‐2 fault block on the Exmouth Plateau, NW Shelf, offshore Australia, using high resolution 3D seismic data. Vertical and headward erosion of the complex and fault throw are measured. Seismic‐stratigraphic and seismic facies mapping allow us to constrain the spatial and architectural variability of depositional systems in the hangingwall. Footwall‐derived systems interacted with hangingwall‐ and axial‐derived systems, through diversion around topography, interfingering or successive onlap. We calculate the volume of footwall‐sourced hangingwall fans (VHW) for nine quadrants along the fault block, and compare this to the volume of material eroded from the immediately up‐dip fault‐scarp (VFW). This analysis highlights areas of sediment bypass (VFW > VHW) and areas fed by sediment sources beyond the degraded fault scarp (VHW > VFW). Exposure of the border fault footwall and adjacent fault terraces produced small catchments located beyond the fault block crest that fed the hangingwall basin. One source persisted throughout the main syn‐rift episode, and its location coincided with: (a) an intra‐basin topographic high; (b) a local fault throw minimum; (c) increased vertical and headward erosion within the fault‐scarp degradation complex; and (d) sustained clinoform development in the immediate hangingwall. Our novel quantitative volumetric approach to identify through‐going sediment input points could be applied to other rift basin‐fills. We highlight implications for hydrocarbon exploration and emphasize the need to incorporate interaction of multiple sediment sources and their resultant architecture in tectono‐stratigraphic models for rift basins

Tectônica e sedimentação na bacia do Paraná : um estudo de caso na região Charqueadas-Triunfo (RS) - fase 1: análise estratigráfica

26

Análise estratigráfica e estrutural do intervalo carbonoso portador de CBM : eo-permiana da Bacia do Paraná

O termo Coal Bed Methane (CBM) refere-se ao metano gerado nas camadas de carvão e é um alvo exploratório na indústria do petróleo. Desde os anos setenta quando o CBM foi visto como uma fonte de energia economicamente viável estudos foram direcionados no entendimento de sua ocorrência, distribuição, viabilidade, produtividade e recuperação (Flores, 1997). Atualmente o CBM é produzido economicamente e investigado em diversas bacias carboníferas do mundo. No Brasil as principais acumulações de carvão são de idade Permiana e fazem parte da Formação Rio Bonito da Bacia do Paraná. De várias jazidas de carvão conhecidas a Jazida de Santa Terezinha, nordeste do estado do Rio Grande do Sul, é a que certamente apresenta o maior potencial para CBM. Seu condicionamento como um baixo estrutural com camadas de carvão de espessuras significativas ocorrendo entre 400m e 1000m de profundidade conferiram a jazida uma situação favorável para geração de metano. Uma boa quantidade de dados geológicos provenientes de diversos poços testemunhados foi utilizada para caracterização estratigráfica do intervalo carbonoso da jazida. A descrição detalhada de testemunhos deu embasamento para análise de fácies e sistemas deposicionais permitindo o reconhecimento de parasseqüências, cujo empilhamento evidenciou uma seqüência deposicional dominantemente transgressiva apresentando na base depósitos aluviais, na porção intermediária sistemas lagunares/paludais com formação de turfeiras, e no topo depósitos marinhos. A análise estrutural revelou uma forte compartimentação tectônica das camadas de carvão, deslocadas por falhamentos normais de alto rejeito. A integração de dados estratigráficos com a determinação do padrão de estruturação atual e demais complexidades forneceu elementos para o reconhecimento de uma zona com melhores condições para exploração de CBM na Jazida de Santa Terezinha.Coal bed methane (CBM0 refers to the methane gas generated in coal beds and is a worldwide target in the petroleum industry. Since the Seventies when CBM was seen like a economically viable energy source studies had been directed to understand it’s occurrence pattern, distribution, viability, productivity and recovery (Flores, 1997). Nowadays CBM is economically produced and investigated in several coaly basins around the world (USA, China). In Brazil the main coal accumulations are of Permian age being part of the Rio Bonito Formation of Parana Basin. From all known coalfields the Santa Terezinha coalfield, in the northeastern region of Rio Grande do Sul state, certainly is the one that presents greater potential to CBM. The structural conditioning and the good thickness of coal beds occurring in depths between 400m and 1000m emplaced the coalfield in a favorable situation to methane generation. Tens of cored wells were utilized to the stratigraphic characterization of the coal bearing interval. A detailed description of cores supplied informations to facies and depositional environments analysis allowing the recognition of parasequences with a dominant retrogradational pattern characterizing a manly transgressive depositional sequence showing aluvial deposits at the base, marsh and lacustrine deposits in middle portion and marine strata on top. The structural analysis revealed a strong tectonic compartmentation of coal beds, displaced by normal faults with high slip. The integration of stratigraphic data with the determination of actual structural patterns and other complexities allowed the recognition of a zone with better conditions to CBM exploration in the Santa Terezinha coalfield

Análise tectono-estratigráfica do intervalo eo-permiano da Bacia do Paraná : estudo de caso na região de Rio Pardo-RS

08

Análise tectono-estratigráfica do intervalo eo-permiano da Bacia do Paraná : estudo de caso na região de Rio Pardo-RS

08

Xenólitos mantélicos da região de Pali Aike, Patagônia Chilena

26

Xenólitos mantélicos da região de Pali Aike, Patagônia Chilena

26