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Orientador: Alessandro Batezelli / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-27T00:28:20Z (GMT). No. of bitstreams: 1 Brito-Silva_KarlaEvenny_M.pdf: 4860012 bytes, checksum: 225791fa027f57898ca7b289e0e9b618 (MD5) Previous issue date: 2014 / Resumo: Estudos voltados para a reconstrução paleoambiental e paleoclimática usando paleossolos vêm crescendo a partir do aumento e melhoramento das técnicas de investigação. Os paleossolos são potencialmente um meio mais direto de fazer reconstruções paleoclimáticas e paleoambientais visto que os solos formam-se na superfície da Terra, em contato direto com a atmosfera e são dependentes das condições climáticas vigentes. Os paleossolos analisados neste trabalho fazem parte da Formação Santo Anastácio ¿ Bacia Bauru e a partir das análises macroscópicas, microscópicas e mineralógica dos mesmos foi possível definir o ambiente de formação de tal unidade, bem com seu paleoclima. O paleossolo (Geossolo Santo Anastácio) caracteriza-se por uma coloração avermelhada, conteúdo carbonático na forma de nódulos e rizoconcreções, elevado conteúdo de quartzo como esqueleto, um plasma composto por argilominerais e óxidos e hidróxidos de ferro, ilita e vermiculita como argilominerais. Acima destes encontramos os depósitos flúvio-lacustres da Formação Araçatuba (Grupo Bauru). As propriedades dos paleossolos nos indicam um ambiente bem drenado, com características oxidantes, com pouca, mas relevante presença de água, em clima semiárido. A presença de um paleossolo remete-nos a uma estabilidade no terreno, o qual propicia um ambiente favorável à pedogênese. A passagem do Grupo Caiuá (Formação Santo Anastácio), para o Grupo Bauru (Formação Araçatuba) é marcada por uma reestruturação tectônica, a qual é responsável por uma mudança paleoambiental. Enquanto o Geossolo Santo Anastácio é indicativo de um ambiente subaéreo, os depósitos flúvio-lacustres da Formação Araçatuba nos indicam um ambiente subaquoso. Se tal disposição mostrar continuidade ao longo da bacia, o mesmo poderá ser útil como marco estratigráfico / Abstract: Paleoevironmental and paleoclimatic reconstructions by paleossols have increase in recent studies due to a new and better technics of investigation. Paleossols are a direct way to do paleoclimatic and paleoenvironmental reconstructions due to the direct contact wirh the atmosfera, witch from soils, and are directly related with climatic changes. The analysed paleossoils in this study are part of Santo Anastácio Formation ¿ Bauru Basin. Macroscopic, microscopic and mineralogical analysis allowed an paleoenvironmental reconstruction and a climatic definition for this unit. This paleossoil (Santo Anastácio Geosol) is characterized by a redish color, carbonatic nodules and rhizoconcretions, high concentrations of quartz as skeleton, plasm composed by clay minerals and iron oxides and hidroxides, illite and vermiculite with clay minerals. Above this soil e found fluvio-lacustrine deposits from Araçatuba Formation (Bauru Group).This properties show us a well draines soil, with oxidant characteristics, low concentration of water in a semi-arid environment. Pedogeneses is favored by a ground stability which leads to a paleossol. Caiuá Group (Santo Anastácio Formation) ¿ Bauru Group (Araçatuba Formation) transition is marked by a tectonic restructuration witch is responsable for a paleoenvironmental change. While Santo Anastacio Geossoil indicates a subaerial environment, the fluvio-lacustrines deposits from Araçatuba Formation show us a subaqueous environment. If this combination remain all over the basin, this could be an important stratigraphic mark / Mestrado / Geologia e Recursos Naturais / Mestra em Geociências

The Malay and Penya Basins, offshore Peninsular Malaysia, were formed during the early Oligocene as a result of regional dextral shear deformation caused by the indentation of India into Eurasia in the early Tertiary. Pre-existing basement inhomogeneities exerted a strong control on basin development. The Penyu Basin developed, initially, as isolated grabens and half-grabens at basement fault intersections, in response to roughly N-S extension. The major structures which include low-angle listric normal faults, pull-apart rhomb grabens and flower structures, suggest that "thin-skinned" crustal extension and strike-slip tectonics have played an important role in basin evolution. Basement faults in the Malay Basin are oblique (E-W trending) to the basin trend (NW-trending). The Basin developed by transtension of NW-trending sinistral shear zone, in which fault-bounded blocks rotate in response to the shear deformation, producing a series of E-trending half-graben depocentres. The Basins were subjected to transpressive inversion during the middle-late Miocene, as a result of rotation of the regional stress field, caused by progressive indentation of India into Eurasia. Subsidence analysis suggests that lithospheric stretching was the dominant process of basin formation. The high heat flows (85-100 mW m⁻²) are consistent with stretching factors, β, of 1.2 to 4.3. In the Malay Basin, uplift of the basin flanks preceeded subsidence during the rifting phase as a result of non-uniform stretching and lateral heat flow from the centre of the Basin. Both basins are undercompensated isostatically and characterised by low negative free-air gravity anomaly in the order of -20 mGal. Undercompensation suggests that the basins were formed, partly, by "thin-skinned" crustal extension which did not involve stretching of the subcrustal lithosphere.

This thesis consists of six published papers. The present-day stress tensor has been determined using petroleum well data in the Gippsland and Otway Basins in Southeast Australia (Papers 1 and 4) and the Cooper Basin in Central Australia (Paper 5). In the Gippsland Basin, the present-day stress regime is transitional between one of reverse and strike-slip faulting and the maximum horizontal stress (SHmax) is oriented ~139°N. The present-day stress regime in the Victorian sector of the Otway Basin is also transitional between one of reverse and strike-slip faulting and SHmax is oriented ~135°N. Horizontal stresses are lower in the South Australian sector of the Otway Basin where the stress regime is one of strike-slip faulting and SHmax is oriented ~124°N. The orientations of SHmax in Southeast Australia are consistent with focal mechanism solutions, neotectonic structures and modelling of plate-boundary forces (Paper 4). Closure pressures from mini-frac injection tests are commonly used to determine the minimum horizontal stress (Shmin) magnitude. However, in high stress basins such as the Cooper and Gippsland Basins, these pressures may not reliably yield Shmin (Papers 2 and 5). In the Cooper Basin, high closure pressures (>18 MPa/km) were observed in tests where pressure-declines indicated complex hydraulic fracture growth. Closure pressures in these injections are unlikely to be representative of Shmin. They are believed to reflect the normal stress incident on pre-existing planes of weakness that are exploited by hydraulic fluid during the mini-frac injection (Paper 5). Sub-horizontal fabrics that are open at the wellbore wall were observed on image logs in the Cooper and Gippsland Basins (Papers 2 and 5). This fabric is believed to be at least partially responsible for the complex growth of hydraulic fractures observed in the Cooper Basin. The occurrence of these sub-horizontal fabrics and knowledge of rock strength have been used to constrain the magnitudes of SHmax and Shmin independently of mini-frac injections in the Cooper and Gippsland Basins (Papers 2 and 5). The present-day stress tensor is often quoted as a single gradient at a sedimentary basinor petroleum field-scale. Image logs and mini-frac data from Central and Southeast Australia indicate significant stress differences between stratigraphic units (Papers 3 and 5). Finite element modelling of the stress distribution between interbedded sands and shales in the Gippsland Basin indicates that stress is ‘partitioned’ to ‘hard’ lithological units in high stress areas. This accounts for the observation that borehole breakout only occurs in hard, cemented sandstones in the Gippsland Basin (Paper 3). A generic ‘mechanical stratigraphy’ derived from knowledge of wellbore failure (from image logs), rock strength and rock properties in individual rock units in the Cooper Basin allows an approximation of the present-day stress-state to be made directly from image-logs for individual rock units prior to mini-frac injection (Paper 6). This is important for predicting and understanding hydraulic fracture growth and containment. When considered together, the papers comprising this thesis provide significant new data on the orientation and magnitude of present-day stresses in Central and Southeast Australia. They also provide insight into the tectonic origin of those stresses and their distribution within sedimentary basins. In particular the papers develop and use new methods for constraining the present-day stress in regions of high tectonic stress. They also discuss implications for problems in petroleum development including wellbore stability and hydraulic fracturing. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1283781 / Thesis(Ph.D.) -- Australian School of Petroleum, 2007