Thesis (Ph. D.)--University of Sydney, 2008. / Includes graphs and tables. Includes list of publications. Title from title screen (viewed December 16, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Division of Geology and Geophysics, School of Geosciences, Faculty of Science. Includes bibliographical references. Also available in print form.

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Στόχος της εργασίας αυτής είναι η δημιουργία ενός συγκεντρωτικού χάρτη, ο οποίος απεικονίζει βαρυτικά γεγονότα στην περιοχή του Κορινθιακού κόλπου. Με βάση τα δεδομένα που πάρθηκαν από την έρευνα που πραγματοποιήθηκε το 1983 με το σκάφος Discovery με τη χρήση του τομογράφου υποδομής πυθμένα και του ηχοβολιστή πλευρικής σάρωσης, καθώς και την επεξεργασία αυτών με το λογισμικό πρόγραμμα GIS, δημιουργήθηκε ένας χάρτης ταξινόμησης των υποθαλάσσιων βαρυτικών γεγονότων. Βάσει αυτού οδηγούμαστε σε συμπεράσματα ως προς τη συχνότητα εμφάνισης, τη γεωγραφική κατανομή αλλά και το είδος των βαρυτικών γεγονότων που εντοπίστηκαν στις καταγραφές. / This work deals with the gravitative submarine mass movements in the seismically active graben; the Gulf of Corinth. The main objective of this work is to create a detailed map of the submarine mass movements of the Gulf of Corinth based on seismic data. The seismic data, consisting of side scan sonar and subbottom profiling records, was collected in 1983 in the framework of a research cruise of the research vessel Discovery. The interpretation of the seismic data was based on certain acoustic criteria and the results were processed with GIS software led to the construction of a classified map. This paper tries to demonstrate the frequency of display, the geological distribution and the type of mass movements, based on the collected seismic data.

Στην παρούσα διπλωματική εργασία πραγματοποιήθηκε επεξεργασία και ανάλυση δεδομένων που συλλέχθηκαν κατά την περίοδο μελέτης της περιοχής της Στούπας στην Νοτιοανατολική Μεσσηνία, στον όρμο της Καλόγριας, με απώτερο στόχο την διερεύνηση του φαινομένου των υποθαλάσσιων εκροών υπογείων υδάτων. / --

Slope channel systems represent significant but highly variable deep-water stratigraphic features and reservoir targets. Variations in architecture and component facies can take place along strike, depositional dip and stratigraphically. A better understanding of these variations permits improved sedimentological and architectural models. By integrating two outcrops (San Clemente, California and Baja California, Mexico) and one subsurface example (offshore Nile Delta), this study provides an opportunity to investigate cross-channel asymmetry, stratigraphic evolution and variability, vertical facies trends, and controls of slope channel systems. This study demonstrates that cross-channel asymmetry in facies and architecture is a lithology- and scale-independent feature, and preferentially occurs at channel bends and in the upper part of slope channel systems. Facies and architectural asymmetry are generally expressed as amalgamated, coarser-grained deposits displaced to the steeper channel edge (outer bend), and finer-grained deposits dominate towards the gentler channel edge (inner bend). A comparison of the systems exposed in Mexico and buried in the subsurface reveals a similar evolutionary trend, from initial sediment erosion/bypass, through early-stage laterally amalgamated channels, late-stage sinuous channels with levees/terraces, and final abandonment. However, pronounced variations exist in the late stage (e.g., presence or absence of lobes), and abandonment stage (e.g., presence or absence of MTDs plugging and channel avulsion). Additionally, for the first time, this study quantitatively demonstrates that early-stage and late-stage architectural elements are characterized by distinct patterns in preferred vertical facies transitions, based on Markov chain analysis of vertical successions. This study also suggests that both extrabasinal factors (e.g., relative sea-level) induced flow energy cycles and intrabasinal factors (e.g., folding and faulting, MTDs, channel bends) can exert a significant control on the architecture and/or evolution of slope channel systems.

Orientador: Jose Ricardo Pelaquim Mendes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Instituto de Geociencias / Made available in DSpace on 2018-08-12T14:15:08Z (GMT). No. of bitstreams: 1 Melo_AndreVerasde_M.pdf: 5529810 bytes, checksum: 4537025b6d5ddedffce982368776dbbd (MD5) Previous issue date: 2008 / Resumo: O cenario de producao em campos de petroleo tem apresentado nos anos recentes condicoes cada vez mais severas e complexas. Muitas descobertas em regioes de maior profundidade e com formacoes geologicas mais diversas tem demandado solucoes tecnológicas que beiram a fronteira do conhecimento, de forma que a producao tem andado lado a lado com o desenvolvimento de novas tecnologias. Assim, a necessidade do aumento do fator de recuperação para justificar os investimentos nestas condicoes sao desafios presentes nos novos projetos de pocos, de elevacao artificial e de recuperacao secundaria, o que vem levando ao desenvolvimento de solucoes submarinas e integradas, como o caso do separador submarino VASPS. No entanto, o controle de processos continuos, como a vazao de producao, a temperatura e a pressao, ainda e tratado da mesma forma que era feito quando do comeco da producao offshore em campos de oleo leve. Este trabalho visa permitir a melhoria de desempenho operacional do sistema VASPS, mensurada pelos custos totais gerados pelo sistema e pelos proventos gerados na producao de oleo e gas, bem como propor novas metodologias de sistemas de controle para sistemas similares, utilizando tecnologias recentes de controle inteligente. Vale ressaltar que o problema de controle e atualmente tratado em campo com solucoes de automacao, sem o estudo devido, causando danos a equipamentos que exigem intervencoes custosas. Os controladores propostos neste trabalho visam minimizar os esforcos aos quais estes atuadores estao expostos, provendo uma maior vida util as tecnologias de elevacao artificial de alta vazão e podendo ser aplicado de forma modular a outros processos relacionados. / Abstract: The oil production scenario has been becoming more and more complex and severe in the recent years. Plenty discoveries in deeper and more diversified formations have been requiring cutting edge technological solutions., such that the production has been deployed side by side with the technological development. Thus, the need for the enhancement of the recuperation factor in order to justify the investment in these new conditions are actual challenges within the recent design of wells, artificial lift systems and secondary recuperation projects, which has been leading to the development towards subsea integrated solutions, such as the VASPS subsea separator. However, the control of continuous processes, i.e. flow, temperature and pressure, is still dealt the same way it was done when the offshore production in light oil fields began. This work envisions the enhancement of the operational performance of the VASPS system, measured as a function of the total costs implied by the technology, altogether with the receipts generated in the gas and oil production, as well as the delivering of new methodologies for the design of controllers using late technologies of intelligent control. Also, it is worth recalling that nowadays the control task is dealt with automation solutions, without the proper handling, causing failures in equipments that require expensive rig intervention for workover. The controllers proposed in this work are designed to minimize the control effort, to which these actuators are exposed, providing extended lifetime to the high level production artificial lift technologies, being also able to be applied to other related processes in a modular form. / Mestrado / Explotação / Mestre em Ciências e Engenharia de Petróleo

The Numidian Flysch Formation is a regionally extensive series of deep marine sandstones and mudstones which crop out in Spain, Morocco, Algeria, Tunisia, Sicily, and southern mainland Italy. The formation is dated as Oligocene to mid Miocene and represents an approximately linear series of submarine fans characterised by a quartz rich petrofacies. Their unique regional extent is nearly twice the length of the Angolan margin although issues surrounding provenance and basin context have hampered understanding. The Numidian Flysch Formation was deposited into the Maghrebian Flysch Basin (MFB) which was a foreland basin remnant of the neo-Tethys ocean in the western portion of the present day Mediterranean Basin. The basin was bordered to the north by an active margin which consisted of a southward verging accretionary prism, underlain by European crustal blocks which rode above northwards subducting oceanic crust. To the south, the African margin formed a passive-margin to the basin.The huge amount of geophysical and outcrop data which is becoming increasingly available suggests that submarine slope systems are more complex than previously thought, including topographically complex slopes, a wide variety of density flow types, and flow transformations. This thesis aims to review the sedimentology of the Numidian Flysch Formation in Sicily and Tunisia in light of these developments. Constraining the provenance and basin context of the formation is therefore of paramount importance, and this is also addressed.Commonly used evidence for the provenance of Numidian Flysch sandstones include its quartz rich petrology, an Eburnian and Pan-African age detrital zircon suite, its structural position within the foreland fold and thrust belt, and complex palaeocurrent orientations. when reviewd in their entirety and placed in context of other basin successions, the Numidian Flysch is constrained to a depositional location in the south of the basin, with polycyclic sediment sourced from African basement. The Numidian Flysch Formation is therefore a 'passive margin' sequence as opposed to a flysch sensu stricto. The timing of Numidian Flysch deposition is also coincidental with uplift of the Atlas chain in North Africa, during a period of significantly wetter conditions. A switch from carbonate to clastic deposition results from these conditions, and the Numidian Flysch Formation is considered an offshore extension of this regional sedimentation.Characterisation of outcrops in Sicily and Tunisia shows remarkably similar lithofacies and depositional elements. Sinuous upper slope channel complexes are entrenched within slope deposits to a depth of 100 m and occur within channel systems up to 5.7 km in width. They are filled predominantly with massive ungraded sandstones interpreted to aggrade through quasi-steady turbidity currents, interbedded with normally graded turbidites. Channel elements are subseismic in scale, are nested within complexes and show sinuosity. Coupled with lateral offset stacking, this strongly affects the architecture and facies heterogeneity of channel complexes. When compared to globally reviewed data, the thickness of channel elements as shown through their frequency distribution also suggests a fundamental control upon the degree of slope incision which is as yet unconstrained.In lower slope settings, channel complexes stack aggradationally with a width of over 1000 m. They are also predominantly filled with massive sandstones in fining upwards cycles, and show heterogeneous margins and large scale slumping. In central Sicily, large channel complexes are overlain by a stacked lobe complex, in turn overlain by a channel lobe transition zone. This progression coupled with palaeocurrent variability suggests intraslope deformation strongly impacts transiting flows through changes in flow capacity. Salt tectonics, present in Algeria and Tunisia is a possible forcing mechanism.Taken in context, the sections in Sicily record a proximal to distal palaeogeographic trend which is reconstructed towards the north/northeast once well constrained tectonic rotations are taken into account. Given regional similarities, controls upon slope architecture are interpreted to be similar throughout the basin, and deposits in Sicily therefore provide a good analogue for the remainder of the basin. These results therefore allow for a better constrained fan architecture, along with the allogenic controls upon them. Given the continental extent of this formation, the Numidian Flysch Formation provides a unique opportunity to study controls upon fan architecture once provenance and intraslope topography is factored in.

In this thesis, I investigate the seismic structure of oceanic lithosphere and asthenosphere with a particular focus on seismic anisotropy, using high-resolution surface waves recorded on ocean-bottom seismometers (OBS) in the Pacific and Atlantic Oceans. The NoMelt (~70 Ma) and Young OBS Research into Convecting Asthenosphere (ORCA) (~43 Ma) OBS experiments located in the central and south Pacific, respectively, provide a detailed picture of ``typical'' oceanic lithosphere and asthenosphere and offer an unprecedented opportunity to investigate the age dependence of oceanic upper mantle structure. The Eastern North American Margin Community Seismic Experiment (ENAM-CSE) OBS array located just offshore the Eastern U.S. captures the transition from continental rifting during Pangea to normal seafloor spreading, representing significantly slower spreading rates. Collectively, this work represents a diverse set of observations that improve our understanding of seafloor spreading, present-day mantle dynamics, and ocean basin evolution. At NoMelt, which represents pristine relatively unaltered oceanic mantle, we observe strong azimuthal anisotropy in the lithosphere that correlates with corner-flow induced shear during seafloor spreading. We observe perhaps the first clear Love-wave azimuthal anisotropy that, in addition to co-located Rayleigh-wave and active source Pn constraints, provides a novel in-situ estimate of the complete elastic tensor of the oceanic lithosphere. Comparing this observed anisotropy to a database of laboratory and naturally deformed olivine samples from the literature leads us to infer an alternative ``D-type'' fabric associated with grain-size sensitive deformation, rather than the commonly assumed A-type fabric. This has vast implications for our understanding of grain-scale deformation active at mid-ocean ridges and subsequent thermo-rheological evolution of the lithosphere. At both NoMelt and YoungORCA we observe radial anisotropy in the lithosphere with Vsh > Vsv indicating subhorizontal fabric, in contrast to some recent global models. We also observe azimuthal anisotropy in the lithosphere that parallels the fossil-spreading direction. Estimates of radial anisotropy in the crust at both locations are the first of their kind and suggest horizontal layering and/or shearing associated with the crustal accretion process. Both experiments show asthenospheric anisotropy that is significantly rotated from current-day absolute plate motion as well as rotated from one another, at odds with the typical expectation of plate-induced shearing. This observation is consistent with small-scale density- or pressure-driven convection beneath the Pacific basin that varies in orientation over a length scale of at most ~2000 km and likely shorter. By directly comparing shear velocities at YoungORCA and NoMelt, we show that the half-space cooling model can account for most (~75%) of the sublithospheric velocity difference between the two location when anelastic effects are accounted for. The unaccounted for ~25% velocity reduction at YoungORCA is consistent with lithospheric reheating, perhaps related to upwelling of hot mantle from small-scale convection or its proximity to the Marquesas hotspot. While lithospheric anisotropy is parallel to the fossil-seafloor-spreading direction at both fast-spreading Pacific locations, it is perpendicular to spreading at the ENAM-CSE in the northwest Atlantic where spreading was ultra-slow to slow. Instead, anisotropy correlates with paleo absolute plate motion at the time of Pangea rifting ~180–195 Ma. We propose that ultra-slow-spreading environments, such as the early Atlantic, primarily record plate-motion modified fabric in the lithosphere rather than typical seafloor spreading fabric. Furthermore, slow shear velocities in the lithosphere may indicate that normal seafloor spreading did not initiate until ~170 Ma, 10–25 Myr after the initiation of continental rifting, revising previous estimates. Alternatively, it may shed new light on melt extraction at ultra-slow spreading environments.

The topic of this diploma thesis is design of a personal submarine for scientific purposes. The main goal is to solve analysed problems, meet the technical requirements, adequate ergonomic solution and morphology for the environment in which the vessel will be employed.

Understanding the past sensitivity of ice sheets and sea level rise in a warmer climate is essential to future coastal planning under the threat of climate change, as accurately modeling impending scenarios depends primarily on data from the past. Extreme warm events during the Quaternary and Neogene periods hold much of the information needed to predict future global climate conditions due to anthropogenic and natural forcings, and may provide unique glimpses of how much future sea level rise can be expected on both short- and long-term timescales. Constraining global mean sea level (GMSL) during past warm periods becomes increasingly difficult the further back in time one goes, especially as precise dating of globally distributed paleoshorelines, along with long-term vertical displacement rates, is essential for establishing GMSL and ice volume history. However, placing chronological constraints on shorelines beyond the limit of U-series radiometric dating (~600 kyr), or at high latitude sites lacking coral, has remained elusive. Even relatively recent warm periods, such as the Last Interglacial (~117-129 ka) has proved challenging for reconstructing GMSL, primarily due to uncertainties in long-term vertical deformation rates and timing of when the highstand occurred. The first two chapters of this thesis address the dating of carbonate shorelines older than ~500 kyr through refinement of the strontium isotope stratigraphy dating methodology. I apply these techniques to a well-known location with numerous uplifted fossil shorelines (Cape Range, Western Australia) to provide the first geochemically derived ages on three fossil shorelines spanning the Pleistocene to the Miocene. Accurate dating and mapping at this location allows correction of long-term vertical displacement. In the last chapter, I use these rates of uplift, in conjunction with twenty new 230Th/U-ages on corals from Western Australia, to refine the timing and peak elevation of the Last Interglacial sea level highstand. Chapter 1 re-evaluates strontium isotope stratigraphy dating techniques for chronologically constraining fossil shorelines from ~0.5 to >30 Ma. Using marine terraces from South Africa, Western Australia, and the Eastern United States as examples, this chapter presents a refined sampling and dating methodology to overcome limitations on diagenetically altered samples, which are ubiquitous in older carbonate shorelines. Discussion on best practices for constraining maximum or minimum ages includes a novel scoring methodology for alteration and a sequential leaching procedure that is specifically suited for shallow-water biogenic carbonate fauna. In Chapter 2, I apply the revised strontium isotope stratigraphy dating methodology to three previously unknown aged terraces in Cape Range, Western Australia. The results obtained show Late-Miocene, Late-Pliocene and Mid-Pleistocene shorelines, which I then use to reconstruct the vertical uplift history of the anticlinal structure and relative rates of deformation. This study is the first to directly date the three terraces, and provides the deformation history necessary for constraining Last Interglacial sea level at Cape Range. In addition, we are able to place maximum relative sea level constraints on all three of these older shorelines. Chapter 3 builds upon the previous chapter by focusing on the Last Interglacial sea level history along ~300 km of coastline in Western Australia (Cape Range and Quobba). This chapter presents new U-series ages on multiple coral heads that are among the highest in-situ corals ever dated in Western Australia, with ages spanning from ~125.3 – 122.6 ka. Detailed geomorphic analysis, particularly at Cape Range, constrains the relative sea level highstand to 6.9 ± 0.4 m. When glacial isostatic adjustment models are applied to the age and elevation data, the resulting Eemian GMSL highstand occurred between 125.5-123.0 ka and reached an elevation between 4.9 and 6.7 m. This is later in the Interglacial and lower in elevation than many recent studies suggest. This dissertation focuses on refining sea level highstands from the Last Interglacial to the Late Miocene in a relatively small (but historically important) region of Western Australia. However, the methodologies presented here provide a powerful multi-proxy dating and mapping approach, which, when applied to regions with multiple marine terraces, can greatly improve the reliability of younger shoreline elevations by reducing neotectonic and dynamic topography uncertainties. The carbonate screening techniques and 87Sr/86Sr stratigraphy dating described here are applicable to a wide range of marine carbonates, with the ability to place accurate chronologic constraints on shorelines from 0.5 to >30 Ma. As I show in chapter 3, when combined with 230Th/U-dating on Late Pleistocene coral in places where multiple marine terraces exist, valuable long-term vertical deformation constraints can allow for far more accurate analysis of sea level in younger paleo shorelines (i.e. Last Interglacial).