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1
Cornwell, David Graham. "Magma-assisted continental rift margins : the Ethiopian rift". Thesis, University of Leicester, 2007. http://hdl.handle.net/2381/30462.
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Continental rifting and incipient seafloor spreading are observed either side of the main Ethiopian rift (MER). EAGLE (the Ethiopia Afar Geoscientific Lithospheric Experiment) included a 400 km-long profile containing 97 passive seismometers to investigate the change from mechanical to magmatic extension by defining the lithospheric structure and extent of magmatism beneath the rifted northern MER. Changes in crustal structure along the cross-rift profile are imaged using forward modelling, H-kappa stacking and non-linear inversion analyses of receiver functions. The lithospheric structure is inherently different beneath the north-western rift flank, rift valley and south-eastern rift flank, with contrasting crustal thickness and composition, upper mantle velocity and lithospheric anisotropy. Magmatic addition is imaged in the form of an 6--18 km-thick underplate lens at the base of the crust beneath the high Ethiopian plateau and zones of intense dyking and partial melt beneath the rift valley. The underplate layer probably formed synchronous with an Oligocene flood basalt event and therefore pre-dates the rifting by ~20 Myr. A 20--30 km-wide magmatic system pervades the entire crust beneath volcanic chains that mark the locus of current rift extension. To the southeast of the rift, a lithospheric suture is inferred, which was created during the Precambrian collision of East and West Gondwana. Collision-related lithospheric fabric is proposed to be the main source of strong anisotropy observed along the entire profile, which is locally augmented by rift-related magmatism. An active followed by passive magma-assisted rifting model that is controlled by a combination of far-field plate stresses, pre-existing lithospheric framework and magmatism is preferred to explain the evolution of the northern MER.
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Davis, Mark Jonathan. "Lithospheric stretching at rifted continental margins". Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367652.
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Trout, Mark N. "Sediment transport and deposition across active faulted rift margins". Thesis, University of Leeds, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247727.
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Stephens, Clare. "Mass flow sedimentation adjacent to rift basin margins, central Greece". Thesis, University of Leeds, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367593.
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Couzens, Timothy John. "The rift to drift transition and sequence stratigraphy at passive continental margins". Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333509.
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Most passive margins display a prominent breakup unconformity coinciding with the rift to drift transition. The unconformity, as defined by Falvey, (1974) is of broad regional extent affecting both basins and highs and is easily recognised on seismic sections. Criteria for the recognition of the breakup unconformity include an inflection in the subsidence curve, fault terminations and volcanic strata (and/or evaporites) at the level of the unconformity. Falvey considered that it was caused by "erosion during the final uplift pulse associated with pre-breakup upwelling in the mantle". It is more likely that the uplift is caused by magmatic underplating in response to the passive upwelling of the mantle and the flexural isostatic effects of erosion throughout the syn-rift phase. The primary objective has been to quantify the amount of uplift and erosion associated with the breakup unconformity / breakup megasequence boundary. This is of particular importance in hydrocarbon exploration as it quantifies the potential loss of old reservoirs and predicts the provenance of new reservoir clastics. Two data sets, from the Grand Banks and the Northwest Shelf of Australia, have been studied. In both cases there are multiple breakup events and breakup megasequence boundaries form part of a complex tectono-stratigraphy. Regional seismic lines have been interpreted, depth converted and modelled using a new technique of combined reverse post-rift and forward syn-rift modelling. The results of this process, together with seismic megasequence analysis, show that the morphology of the breakup megasequence boundary varies systematically across a passive margin. It is strongly erosional at about 70 km landward of the continentocean boundary, where regional "breakup" uplift outweighs extensionally controlled subsidence, but may be depositional on either side of this zone. A coupled, quantitative magmatic-tectonic model has been constructed by combining the Bickle-McKenzie melt generation model with the flexural cantilever model for continental extension. The magnitude of underplating can be estimated using the Bickle-McKenzie model, in which the amount of melt produced is controlled by the extension factor, ß, and the proximity of a mantle plume convection cell.
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Soares, Duarte. "Sedimentologial and stratigraphical aspects of the syn- to post-rift transition on fully separated conjugate margins". Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/68378/.
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The integration of several industry and scientific 2D seismic surveys with various well data allowed for the first time a detailed analysis of the sedimentological, stratigraphic and architectural changes recorded during syn- to post-rift transitions on passive margins. The Northwest Iberia margin and its conjugate margin of Newfoundland formed the basis for an interpretive model. Comparison with the South Australia�East Antarctica conjugate margins enabled hypothesis testing and premise refinement. The breakup unconformity concept is revised and a more comprehensive term is proposed for the stratigraphic surface recording the transition between syn- and post-rift: the lithospheric breakup surface. This new term: a) discriminates between continental crust breakup and complete lithospheric breakup as verified in several magma-poor margins, and b) takes into account the different character this surface can show according to its position on the margin. The concept of a breakup sequence is proposed as a sedimentary sequence showing a distinct architecture to strata deposited prior to the lithospheric breakup event. The breakup sequence records the depositional changes occurring across the lithospheric breakup surface due to lithospheric adjustments triggered by lithospheric breakup. Contourites were identified for the first time as being associated with lithospheric breakup, supposedly being triggered by the lithospheric plate in-plane stress release occurring at the time of lithospheric breakup. Consequently, it is proposed that contourites can be used as an indicator for established lithospheric breakup. On the East Antarctica margin, a surface usually dated as mid Eocene to early Oligocene by comparison with the conjugate South Australia margin, is dated as latest Maastrichtian�earliest Palaeocene using data from IODP Site 1356. This new date suggests that the surface is a lithospheric breakup surface, which can explain its generation and the overlying strong contouritic deposition.
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Stab, Martin. "Interactions tectono-magmatiques au cours de l’extension des marges volcaniques : nouvelle lecture de l’évolution de la province Afar en tant qu’analogue actif". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066600/document.
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Les marges passives volcaniques, qui représentent plus des trois-quarts des marges passives sur Terre, sont les témoins privilégiés des processus d'extension lithosphérique menant à l'ouverture de nouveaux bassins océaniques. Nous explorons les relations structurales et temporelles qui existent entre le développement des grandes structures qui accommodent l'extension et l'amincissement, et la production magmatique qui lui est associée pendant le développement d'une marge volcanique naissante, accessible à l'observation directe : le point triple Afar en Éthiopie. Nous produisons une nouvelle lecture de la province Afar en tant qu'analogue en devenir des marges volcaniques. L'approche combine (1) une étude de terrain et de datation du volcanisme pour caractériser le timing de la déformation crustale et le style structural du rift pendant les phases les plus précoces, (2) la détermination géochimique de l'évolution des régimes de fusion mantellique au cours de l'extension, (3) la construction d'un modèle régional qui traite de l'évolution des marges volcaniques en lien avec leur segmentation. Nous mettons en évidence un style structural de " magmatic wide rift " en Afar, associé au jeu de grands détachements. Des phases tectoniques ponctuelles alternent avec des périodes de magmatisme plus prolongées. La segmentation précoce syn-rift contrôle le style structural, la mise en place du magma et l'asymétrie des marges. Le break-up correspond à l'amincissement et le remplacement de la croûte initiale par du matériel mafique pour former la première croûte océaniqueVolcanic passive margins, that represent more than the three quarters of continental margins worldwide, are privileged witnesses of the lithospheric extension processes that form new oceanic basins. We explore the structural and temporal relationships that exist between the development of the major thinning and stretching structures and the magmatic production associated to them. To do so, we will focus our work on the Afar triple junction, Ethiopia, a nascent volcanic passive margin. The rationale of this work is threefold. First, we present fieldwork analysis with lavas geochronology to determine the timing and style of the rift formation, since the early syn-rift period to present days. Second, we determine how the melting regime evolved in response to the deformation of the crust, through a geochemical study of the pre- to syn-rift lavas. Third, we present a synthetic regional that describes the evolution of the volcanic margins in relationship with their segmentation. Central Afar deformed as a magmatic wide rift, associated with major detachment faults. Punctual tectonic phases alternate with protracted magmatic periods. Early syn-rift segmentation controls the structural style, magma emplacement and asymmetry of the margins. The break-up is reached when the initial crust is thinned and replaced by mafic material to form the first oceanic crust
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Burgess, Peter Mark. "A quantitative forward modelling analysis of the controls on passive rift-margin stratigraphy". Thesis, University of Oxford, 1994. http://ora.ox.ac.uk/objects/uuid:1249833d-ef11-4327-bdbd-5d0c40faa29e.
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A quantitative forward model has been developed to investigate the controls on the deposition, erosion, and preservation of passive rift margin stratigraphy. The model includes thermal subsidence, variable absolute sealevel, flexural isostasy, subaerial and submarine deposition on fluvial and marine equilibrium profiles, and the facility to vary sediment supply through time. Results from the quantitative model can be used to reproduce elements of the sequence stratigraphic depositional model. Conducting sensitivity tests demonstrates that variables such as sediment supply and fluvial profile behaviour are likely to be of equal importance to thermal subsidence and eustasy in passive margin stratigraphy. Sensitivity tests with the quantitative model also demonstrate the problems associated with attempting to use a discretised stratigraphic model to investigate unforced cyclicty resulting from complex interactions in stratigraphic systems. Although the model appears capable of producing such unforced cyclical behaviour, this cyclicity is shown to be due to a numerical instability within the model which occurs with certain initial conditions and assumptions. The applicability of the model to observed stratigraphy is tested by comparing specific model output to patterns of stratigraphy from the North American Atlantic margin. The results from this test demonstrate that although the model is in many respects simplistic when compared to the complexities of natural systems, it is nevertheless capable of reproducing some of the basic elements of the observed stratigraphic patterns.
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Russell, Simon Mark. "A magnetic study of the west Iberia and conjugate rifted continental margins : constraints on rift-to-/drift processes". Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4358/.
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The analysis and modelling of magnetic anomalies at the conjugate rifted continental margins of the southern Iberia Abyssal Plain (TAP) and Newfoundland Basin have revealed that the sources of magnetic anomalies are distinctly different across both each margin and between the two margins. Analyses of synthetic anomalies and gridded sea surface magnetic anomaly charts west of Iberia and east of Newfoundland were accomplished by the methods of Euler deconvolution, forward and inverse modelling of the power spectrum, reduction-to-the-pole, and forward and inverse indirect methods. In addition, three near-bottom magnetometer profiles were analysed by the same methods in addition to the application of componental magnetometry. The results have revealed that oceanic crust, transitional basement and thinned continental crust are defined by magnetic sources with different characteristics. Over oceanic crust, magnetic sources are present as lava-flow-like bodies whose depths coincide with the top of acoustic basement seen on MCS profiles. Top-basement source depths are consistent with those determined in two other regions of oceanic crust. In the southern IAP, oceanic crust, ~4 km thick with magnetizations up to +1.5 A/m, generated by organized seafloor spreading was first accreted -126 Ma at the position of a N-S oriented segmented basement peridotite ridge. To the west, seafloor spreading anomalies can be modelled at spreading rates of 10 mm/yr or more. Immediately to the east, in a zone -10-20 km in width, I identify seafloor spreading anomahes which can only be modelled assuming variable spreading rates. In the OCT, sources of magnetic anomalies are present at the top of basement and up to -6 km beneath. I interpret the uppermost source as serpentinized peridotite, and the lowermost source as intruded gabbroic bodies which were impeded, whilst rising upwards, by the lower density serpentinized peridotites. Intrusion was accompanied by tectonism and a gradual change in conditions from rifting to seafloor spreading as the North Atlantic rift propagated northwards in Early Cretaceous times. Within thinned continental crust, sources are poorly lineated, and distributed in depth. Scaling relationships of susceptibility are consistent with the sources of magnetic anomalies within continental crust. OCT-type intrusions may be present in the mantle beneath continental crust. At the conjugate Newfoundland margin, seafloor spreading anomalies can be modelled at rates of 8 and 10 mm/yr suggesting an onset age consistent with that of the IAP. In the OCT there, I propose that magnetic anomalies are sourced in near top-basement serpentinized peridotites. An absence of magmatic material and the differences in basement character (with the IAP) suggest that conjugate margin evolution may have been asymmetric.
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Pinto, Victor Hugo. "Linking tectonic evolution with fluid history in hyperextended rifted margins : examples from the fossil Alpine and Pyrenean rift systems, and the present-day Iberia rifted margin". Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAH018/document.
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Cette thèse est centrée sur la caractérisation des traceurs des fluides qui interagissent avec les roches du socle et les roches sédimentaires dans les systèmes riftés hyper-amincis exposés dans la Téthys alpine, les Pyrénées et Ibérie-Terre Neuve. L’étude de ces fluides est basée sur les observations géologiques, les analyses géochimiques et les données géophysiques. Deux types de fluides ont été identifiés : les fluides associés à la croûte continentale, avec une signature caractérisée par Si et Ca, ainsi que les fluides liés au manteau en exhumation, avec une signature caractérisée par Si, Mg, Fe, Mn, Ca, Ni, Cr et V. La percolation des fluides est fortement liée à la formation des failles de détachement et à l’évolution des systèmes hyper-amincis. Le flux de fluides dans ces systèmes a des implications importantes pour les changements rhéologiques, pour la nature des sédiments et pour les modifications chimiques des réservoirs de la TerreThis thesis focus in the identification of geochemical tracers and effects of fluid that interact with basement and sedimentary rocks in hyperextended systems. The investigation of such fluids is based on geological observation, geochemical analyses and geophysical data from fossil hyperextended rift systems exposed in the Alps and in the West Pyrenees, and the present-day distal margins of Iberia and Newfoundland. Two types of fluids were identified during this study. The first type, referred to as continental crust-related fluids, has a signature of Si and Ca. The second type, referred to as mantle-related fluids, has a signature of Si, Mg, Fe, Mn, Ca, Ni, Cr and V. The fluid percolation is strongly related to the formation of extensional detachment faults and the evolution of hyperextended systems. Fluid flow in these systems has major implications for the nature of sediments, rheological changes and chemical modifications of the Earth’s reservoirs throughout its evolution
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Sahota, G. "Geophysical study of the Gulf of Aden continental margins : geodynamic implications for the development of the Afro-Arabian Rift System". Thesis, Swansea University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638740.
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This thesis contains gravity, magnetic and seismic data from two surveys over the Gulf of Aden. It examines the structure of the continental margins, the seafloor spreading history of the Gulf and the geodynamic implications for the development of the Afro-Arabian Rift System. Total opening has occurred by crustal extension and seafloor spreading. The extent of seafloor spreading opening in the Gulf of Aden (and Red Sea) is greatest farthest from the Eulerian opening pole; crustal extension increases as the angular distance to the opening pole decreases. In the eastern Gulf, average B is 1.4 across the margins and the transition from continent to ocean occurs over 40 km. In the central and western Gulf, average B is 1.7 and the continent-ocean transition zone is 50-80 km wide. The transition zones are magnetically quiet. The extension mechanism changes from pure shear extension in the east to pure shear extension with dyke injection in the west. Seafloor spreading models of the Gulf show that oceanic crust has formed at Sheba Ridge axis in a single continuous episode. Oldest oceanic crust in the Gulf is about 20 Myr (anomaly 5E) and not 10 Myr (anomaly 5) as widely cited in the literature. This work does not support the 2-stage seafloor spreading models proposed for the Gulf of Aden and Red Sea. The location of rift boundary faults, continental margins, fracture zones, magnetic quiet zones and oceanic crust in the Gulf can be explained by a rift tip migrating through the lithosphere toward the Arabia-Somalia opening pole. The propagating rift focused the extension along the weakest part of the lithosphere until it split apart to form a seafloor spreading axis. The seaward magnetic quiet zone boundary is not an isochron and the age of the oldest isochron decreases poleward. Up to 10 Myr differences in the oldest isochron occur across major fractures, where oceanic crust juxtaposes magnetic quiet zone crust. Occasionally, rift tip propagation slowed across zones resistant to fracturing or 'soft zones'. Across these, plate divergence ahead of the rift tip occurred by crustal extension forming magnetic quiet zones while behind, new crust was emplaced at the oceanic rift. Major fractures temporarily separated crustal extension zones from seafloor spreading zones. Eventually the crust split apart and the rift tip continued its poleward migration; it presently lies near Lake Asal, at the western end of the Tadjurah Gulf. The evolution of the Gulf constrains the timing of plate motions in the Gulf of Aden-Red Sea area to continuous development since Late Oligocene-Early Miocene. Only the narrow axial zone of the southern Red Sea is underlain by oceanic crust formed in the last 5 Myr. The remaining opening across the flanking wide main troughs and also across the entire northern Red Sea has occurred by pure shear extension with dyke injection over the last 20 Myr. Total opening in the Gulf of Aden and plate kinematics suggest 125% extension across the northern Red Sea and Suez Gulf, a figure supported by existing field data.
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Incerpi, Nicolo. "Hydrothermal systems in distal rifted margins and their role in the thermal evolution of sedimentary successions : study of two fossil analogues in the Swiss Alps and Pyrenees". Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAH005/document.
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Les données sismiques et les forages des marges continentales distales permettent de comprendre l'architecture et l'évolution de ces domaines, dont l’évolution thermique est peu connue, même si on connaît que les systèmes hydrothermaux jouent un rôle clé dans la distribution des flux de chaleur. Cette thèse vise à étudier les produits diagénétiques dans les sédiments de pré- à post-rift, qui enregistrent l'évolution des interactions roche-fluide. Deux analogues fossiles ont été étudiés: la marge distale adriatique et le système hyper-étiré pyrénéen. Les études de terrain, pétrographiques et géochimiques révèlent une forte hétérogénéité dans la composition des fluides. Dans les premières phases de rifting, dominées par des failles normales à fort pendage, les fluides sont riches en carbonate,tandis que dans les dernières phases, caractérisées par des failles de détachement à faible pendage qui exhument les roches de la croûte continentale et du manteau, les fluides résultent riches en silice. Cette thèse a donc démontré que l'évolution tectonique des marges de rifting comporte aussi des changements spécifiques dans la chimie des fluides hydrothermauxSeismic and drill hole data from deep-water distal rifted margins allow to understand the architecture and evolution of these yet little investigated domain. Nonetheless, the thermal evolution is poorly constrained even if hydrothermal systems play a key role in determining the heat fluxes. This Thesis aims to investigate breccias, cements, veins and replacement minerals within the pre- to post-rift sediments that could testify the space-time evolution of rock-fluid interactions. Two fossil analogues are studied: the Adriatic distal margin and the Pyrenean hyper-extended system. Field, petrography and geochemical analyses reveal a strong heterogeneity in the composition of the fluids as well as their hydrothermal features. Two main types of fluids occur: carbonate-rich fluids refer to early rifting phases dominated by high-angle normal faults; silica-rich fluids are related to the last rifting stages characterized by low-angle detachment faults exhuming upper crust and mantle-related rocks. The results of this Thesis highlight how specific changes in the chemistry of the fluid system are intimate lylinked to the tectonic evolution of rifted margins
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Gimeno-Vives, Oriol. "L’évolution tectono-sédimentaire des marges de la Téthys dans le système orogenic Rifain". Thesis, Cergy-Pontoise, 2019. http://www.theses.fr/2019CERG1028.
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La chaîne du Rif (Maroc du nord) est une chaîne de montagnes située à la jonction entre Atlantique Central et domaine méditerranéen. Constituant l’extrémité occidentale des Maghrébides, il appartient à la catégorie des chaînes alpines issues de la Téthys qui se poursuivent jusqu’à l’Himalaya et au-delà. Plus précisément, le Rif résulte de la collision entre deux ensembles continentaux séparés initialement par une branche de la Téthys. Le Rif est subdivisé en trois grands domaines: (1) Les zones internes, (Rif Interne), constituées d’une pile de nappes souvent métamorphiques. (2) Le domaine des Flyschs (couverture sédimentaire de la Téthys Maghrébine). (3) Les Zones externes, héritées de l’ancienne marge passive nord-africaine.Malgré des événements compressifs spectaculaires, le Rif apparaît comme un site intéressant pour l’étude des processus de rifting et d’océanisation. En effet, des traces de la marge passive mésozoïque de l’Afrique du Nord sont remarquablement bien préservées. Ce qui même assez exceptionnel est la possibilité d’accéder à la partie la plus distale de l’ancienne marge. Cette thèse, présente une étude de terrain détaillé et de nouvelles données géo et thermo-chronologiques pour proposer une interprétation moderne du zonage paléogéographique et, en particulier, du Mésorif et de l’Intrarif.Le Mésorif montre une phase de rifting majeure pendant le Jurassique Moyen; Cette phase est typique de la Téthys Maghrébine. On observe un cortège gabbroïque supportant tectoniquement la plate-forme carbonatée du Jurassique Inférieur totalement démembrée. Des datations U-Pb sur zircon sur le gabbro révèle des âges à 195-200 Ma, c’est-à-dire à la transition Trias-Jurassique. Chronologiquement et pétrographiquement, les gabbros mésorifains au fameux événement CAMP (Central Atlantic Magmatic Province), connu autour de l’Atlantique Central et au-delà.L’Intrarif porte les traces d’un processus d’exhumation du manteau. Celui-ci affleure dans le Massif de Béni Malek sous la forme de péridotites serpentinisées et d’ophicalcites supportant stratigraphiquement le Jurassique terminal. Cette observation permet de caler dans le temps l’initiation de l’océanisation dans la Téthys Maghébine. Mises ensemble, ces observations donnent des contraintes fortes pour discuter de l’architecture et de l’évolution de la partie ouest de l’ancienne marge nord-africaine.La localisation du Rif, à l’ancienne jonction entre l’Atlantique Central et la Téthys Maghrébine permet de discuter des relations entre ces deux domaines au Mésozoïque. Mon travail se situe dans la continuation de l’étude magistrale de cet auteur. Cependant, à l’aide des nouveaux concepts et modèles développés depuis cette période, j’ai été en mesure de proposer un scénario renouvelé incluant le poly-rifting, la mise en place de gabbros et l’exhumation du manteau.A partir du Crétacé Supérieur, la marge nord-africaine va subir une histoire complètement différente et change de statut: celle-ci va rentrer en convergence à l’instar du domaine téthysien tout entier. Le Rif externe présente plusieurs caractéristiques rares dans un contexte de zones externes de chaîne de montagnes: (1) Il enregistre une déformation polyphasée avec un événement compressif précoce, pré-Oligocène, antérieur au chevauchement miocène des Zones Internes sur les Zones Externes. (2) Il inclut des Massifs Métamorphiques Externes enregistrant un gradient de type HP-BT. (3) Il inclut de grandes nappes de charriage identifiées depuis longtemps jusqu’au front de chaîne.La thèse est basée sur une étude de terrain à différentes échelles (synthèse cartographique, étude détaillée d’affleurements); elle cherche à caractériser toutes les étapes de la formation du Rif Externe depuis la formation de la marge nord-africaine jusqu’à la formation de la chaîne et l’état actuelThe Rif belt (northern Morocco) is a mountain chain at the junction between the Mediterranean and Central Atlantic Domains, representing the western edge of the Maghrebides System. It belongs to a much larger orogeny, the Mediterranean Alpine belts extending from the Western Mediterranean up to the Himalayas. The Rif belt results from the collision between two continental domains initially separated by the Maghrebian Tethys.This belt is classically subdivided into: (1) Internal zones (or Internal Rif), is an allochthonous metamorphic domain. (2) Flysch zones (the original cover of the Maghrebian Tethys). (3) External zones (or External Rif) representing the North African margin remnants.Despite spectacular compressional events, the Rif represents a remarkable place for the understanding of rifting and oceanization mechanisms and their incorporation in mountain belts, because remnants of the Mesozoic North African rifted margin are especially well preserved in its external zones. Especially, the External Rif conserves characteristics of the distal margin. This thesis presents detailed field evidence and geochronological data from two subunits of the External Rif, the Mesorif, and the Intrarif.- The Mesorif preserves a major rifting phase during the Middle Jurassic, characterizing the formation of the Mesozoic North African margin. It presents particular lithostratigraphic associations of mafic intrusive rocks overlain by dismembered and discontinuous blocks of Lower Jurassic carbonates covered by Middle to Upper Jurassic sediments. U-Pb zircon dating of 4 samples from the intrusive has been done, showing ages close to the Triassic-Jurassic boundary (195-200 Ma). From a petrographic and chronologic point of view, the intrusive magmatism, corresponds to the CAMP (Central Atlantic Magmatic Province), known around the Central Atlantic.- The Intrarif displays the exhumed mantle domain, exposed in the Beni-Malek massif, consisting on highly serpentinized peridotites exhibiting ophicalcites with uppermost Jurassic limestones resting conformably on top. This suggests that the exhumation of the mantle occurred at the distal part of the North African Mesozoic margin at this time. Altogether, these observations enable us to discuss the architecture and evolution of the western part of the North African rifted margin.Moreover, the location of the Rif, in between the Central Atlantic and the Alpine/Maghrebian Tethys, enables to investigate the connection between these two oceanic domains during the Mesozoic. However, thanks to the new concepts and models developed since this period, we are able to propose a renewed scenario for the building of this margin. As we will see this scenario implies poly-phase rifting, magmatic activity and mantle exhumation.Later on, by the Late Cretaceous, the North African margin has suffered a complete different history, passing from a passive margin to a convergence setting, affecting the whole Tethys Realm. The External Rif presents several features that are unusual in the external zones of a mountain belt:-They record poly-phase deformation events with evidence for an early and initial (pre-Oligocene) contractional event occurring before the Miocene thrusting of the Internal Units over the External Units.-They include the presence of External Metamorphic Massifs (EMM) recording a HP-LT metamorphic gradient.-They exhibit large allochthonous thrust-sheets identified since a long time across the whole External Rif.The thesis is based on the onshore study of the geodynamic evolution of the Rif belt since the earliest stages of the North African Mesozoic margin formation, through the compressional stages of mountain building, up to its present day position
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Mohamed, Hwedi Abdulsalam. "The Holocene palaeoenvironments of the rift margin in Southern Jordan (Wadi Faynan)". Thesis, University of Huddersfield, 2000. http://eprints.hud.ac.uk/id/eprint/4871/.
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Wolfenden, Ellen. "Evolution of the southern Red Sea Rift : birth of a magnetic margin". Thesis, Royal Holloway, University of London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405194.
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Kirkland, David Andrew. "The influence of syn-rift structural segmentation over the post-rift geological evolution of the equatorial Gulf of Guinea rifted continental margin". Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343853.
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Kirkland, David Andrew. "The influence of syn-rift structural segmentation over the post-rift geological evolution of the equatorial Gulf of Guinea rifted contenental margin". Online version, 1999. http://ethos.bl.uk/OrderDetails.do?did=1&uin=uk.bl.ethos.343853.
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Moy, David John. "The architecture, growth and tectono-stratigraphic significance of rift-oblique lineaments on the NE Atlantic Margin". Thesis, Durham University, 2010. http://etheses.dur.ac.uk/178/.
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Fault domain boundaries are characteristic features of segmented rift systems and have been recreated in analogue models. Two end member conceptual models of fault domain boundaries currently exist. 1) Accommodation zones, which are broad regions of overlapping normal faults and which trend oblique to the rift axis. 2) Transfer zones, which are discrete sub-vertical fault systems that directly link en-echelon normal fault domains. These structures are commonly believed to segment natural rift systems on a variety of scales and impact directly upon the stratigraphic and magmatic evolution of a basin. The NE Atlantic Margin is a volcanic passive margin which has undergone a series of rift events culminating with continental breakup in the Early Cenozoic. From potential field, seismic reflection, seismic refraction and ocean bottom seismometer datasets, a series of rift-oblique lineaments (loosely referred to as ‘transfer zones’) have been identified which are commonly inferred to compartmentalise and laterally offset structural highs and depocentres developed within the Mesozoic – Cenozoic rift basins. A range of hypotheses are proposed to explain the origin of these lineaments, including fault domain boundaries, basin-wide strike-slip faults and other, non-tectonic origins. Using well-calibrated 2D and 3D seismic data, this study critically assesses the structural, stratigraphic and magmatic evidence for the rift-oblique lineaments in the Faroe-Shetland Basin and Vøring Basin, both located upon the NE Atlantic Margin. Results from the Faroe-Shetland Basin show structures previously attributed to basin-wide strike-slip deformation can be more simply explained as igneous intrusions, hydrothermal vent complexes, gas chimneys and/or faults that transfer extensional strain between en-echelon rift segments (i.e. fault domain boundaries). There is little evidence to suggest that activity along a series of discrete, basin-wide lineaments controlled Paleocene sedimentation in the basin. In the northern Vøring Basin, a previously identified fault domain boundary (the Rym Accommodation Zone) is analysed to understand if, and how strain is transferred between two adjacent fault domains. The results of this study highlight major differences between the offset rift segments in view of the style of rifting, timing, the loci of faulting, the relative uplift and subsidence histories as well as the impact of variations in the deep crustal structure. Analyses reveal that strain is not fully transferred across the fault domain boundary, with significant variation in beta factors calculated for each rift segment. The structural style within the Rym Accommodation Zone is complex, with the rotation of normal fault orientations, major relay ramp formation and rift perpendicular normal oblique faulting observed, elements that are not present in most existing conceptual models of accommodation zones. The results also imply that transfer zones may be an integral part of a larger accommodation zone rather than an opposite end member as previously believed. In the final aspect of the study, a second rift-oblique lineament is analysed in the northern Vøring Basin: the Gleipne Lineament. Results highlight the close structural relationship between the Gleipne Lineament and underlying basement structure, with the lineament acting as a conduit for sediment to enter the Vøring Basin during phases of rifting. Under periods of minimal upper crustal deformation, the lineament exerted a lesser control upon basinal sedimentation. The Rym Accommodation Zone in contrast did not source sediment into the Vøring Basin, instead, it compartmentalised the basin during rifting which increased the complexity of the predicted basin fill. Increased Late Paleocene intrusive and extrusive igneous deposits are observed along the strike of both lineaments but are not directly linked to active tectonic deformation. In conclusion, rift-oblique lineaments are unlikely to be basin-wide features and each appears to be unique in its structural style and geological origin. In turn, this means that different lineaments are likely to have different impacts upon the stratigraphical and magmatic development of a basin. Previous inferences that basin-wide lineaments have controlled sediment entry and transport within rift basins on the NE Atlantic Margin need to be substantiated on a case-by-case basis. The results of this study are further considered and discussed to predict the nature of rift-segmenting structures in the sub-basalt region of the Faroe-Shetland Basin, which is poorly resolved by current 2D and 3D seismic imaging.
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Baurion, Céline. "Architecture sédimentaire et dynamique post-rift des marges conjuguées du Golfe d'Aden oriental". Paris 6, 2012. http://www.theses.fr/2012PA066708.
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Ce travail présente une analyse combinée des domaines continentaux et marins sur les marges conjuguées du golfe d’Aden oriental au cours des derniers 20 Ma. L’objectif principal de la thèse est de comprendre l’évolution de l’architecture sédimentaire au cours des toutes premières étapes de formation des bassins profonds et des marges continentales étirées. Les mécanismes contrôlant la mise en place d’une sédimentation gravitaire dans les stades précoces de la subsidence sont précisés. Il s’agit d’une étude intégrée, prenant en compte les processus tectono-sédimentaires opérant depuis les bassins versants jusqu’à la pente continentale et le bassin profond. Cette étude nous a permis de mieux contraindre l’évolution de la sédimentation et des structures post-rift des marges continentales étirées à partir des données multifaisceaux, de sismique réflexion et très haute résolution, de l’analyse de carottes sédimentaires et de la datation par cosmonucléides de terrasses marines quaternaires. L’interaction des facteurs de contrôle externes (climat, eustatisme) et la permanence de la segmentation structurale sont à l’origine de la variabilité latérale des structures des marges conjuguées du golfe d’Aden oriental sur des distances relativement courtes. Les structures majeures héritées de la phase de rifting rejouent au cours d’une phase post-rift de soulèvement des marges. Ce travail de thèse constitue un modèle d’évolution tectono-sédimentaire qui permettra de mieux contraindre l’architecture sédimentaire des marges continentales à des stades plus avancésThis thesis presents a combined analysis of continental and marine domains of the conjugate margins of the eastern Gulf of Aden along the last 20 Ma. The main objective of the research is to understand the evolution of the sedimentary architecture in the early stages of the formation of deep basins of stretched continental margins. The mechanisms monitoring the implementation of gravity-driven sedimentation during the early subsidence stages are specified. This integrated study, takes into account the tectono-sedimentary processes operating from the watershed to the continental slope and the deep basin. This study has allowed us to constrain the post-rift evolution of the sedimentation and related structures of these stretched continental margins, through multibeam data, seismic reflection, Chirp data, analysis of sedimentary cores and cosmogenic nuclides dating of Quaternary marine terraces. The interaction between external controlling factors (climate, eustasy) and the durability of the structural segmentation are responsible of the lateral variability of the sedimentary structures over short distance along the conjugate margin of the eastern Gulf of Aden. The main structures inherited from the rifting stage are reactiviated during a post-rift uplift of the margins. This study constitutes a model of the tectono-sedimentary evolution, which will enable to better constrain the sedimentary architecture of continental margins in more advanced stages of evolution
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Sibuet, Jean-Claude. "Contribution à l'étude des mécanismes de formation des marges continentales passives". Brest, 1987. http://www.theses.fr/1987BRES2016.
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Les modeles de formation et d'evolution des marges continentales passives n'ont pu etre elabores, modifies et testes que parce que de nombreux leves geologiques et geophysiques de detail ont ete acquis. D'ou : au cours de l'episode de rifting, les directions des mouvements des plaques amerique du nord, europe et iberie sont identiques aux directions d'ouverture du domaine oceanique adjacent. Il faut quantifier l'extension totale resultant du rifting ce qui necessite de mieux apprehender les processus de formation des marges. Les donnees de la marge ouest-iberique sont cependant compatibles avec le modele d'etirement uniforme. Ce type de marge pourrait etre considere comme l'evolution finale d'un bassin intra-continental symetrique cree par etirement uniforme. En ce qui concerne la marge nord-gascogne, on suppose qu'une surface de decollement, traversant toute la croute superieure jusqu'a l'interface fragile-ductile, a fonctionne des le debut de la phase de rifting. Les failles limitant les blocs bascules sont alors des failles antithetiques. Ce type de marge pourrait etre considere comme l'evolution finale d'un bassin intra-continental asymetrique. A titre d'hypothese, on propose un modele de formation de marge continentale par etirement uniforme.
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Deschamps, François. "Évolution post-rift et enregistrement des mouvements verticaux le long des marges passives : effets des processus intrinsèques aux marges passives". Rennes 1, 2010. https://hal-insu.archives-ouvertes.fr/tel-01137274.
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Les marges passives sont des structures lithosphériques intra-plaques, assurant la transition entre une croûte continentale non amincie et une croûte océanique. Du fait de leur position en bordure des continents, les marges passives sont soumises à des flux sédimentaires externes au système, produits par l'érosion de reliefs continentaux en amont de la marge, et elles sont affectées par une déformation complexe et de faible intensité qui intègre la déformation produite par les processus intrinsèques au système (ex : isostasie flexurale, subsidence thermique) mais aussi les déformations intra-plaques, et enfin les déformations en limite de plaque. Les bassins sédimentaires des marges passives en domaine marin et les données de dénudation en domaine continental enregistrent donc, de manière indépendante, des processus locaux, régionaux ou globaux. Jusqu'à présent, les études publiées sur les marges passives ont le plus souvent été segmentées entre, d'une part, les domaines non aminci et de transition, et d'autre part, le domaine aminci des marges passives. Pour approfondir nos connaissances sur le comportement et l'enregistrement post-rift des marges passives, nous avons réalisé, à l'aide d'un nouveau modèle numérique 3D couplant des processus thermiques, de l'isostasie flexurale et des processus de surface, une nouvelle étude intégrant la marge depuis le domaine continental non aminci jusqu'au domaine aminciPassive margins are intra-plate lithospheric structures located at the transition between continental and oceanic crust. Because of their location on the border of continents, passive margins record sediment transfer, produced by erosion of continental relief far from the margins, and complex and low intensity deformations produced by intrinsic processes (eg, flexural isostasy, thermal subsidence), intra-plate deformations, and plate boundary deformation. The sedimentary accumulation in basins and the continental denudation result in local, regional, and global processes with complex coupling. Up to the present, published studies on passive margins have generally been segmented between, unstretched and transitional domains and stretched domain of passive margin. To improve our understanding of post-rift deformation and recording of passive margin, we have done a new study incorporating the margin since unstretched domain to stretched domain. We used in this study, a new 3D numerical model coupling thermal processes, the flexural isostasy and surface processes
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Delpech, Pierre-Yves. "Rifting jurassique sur la bordure occidentale du dome de barrot (alpes occidentales francaises) : evolution geodynamique d'un secteur de la marge nord-tethysienne". Paris 6, 1988. http://www.theses.fr/1988PA066189.
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L'analyse des variations laterales de facies permet de reconstituer un schema du secteur du haut-var coherent a condition de placer un accident de direction n 20-30 a vergence ouest ayant joue en faille normale au cours du lias et du dogger et limitant un domaine de bassin a l'ouest et une plate-forme a l'est. Les manifestations tectonosedimentaires observees suggerent, outre les deformations dues a la tectonique distensive, l'existence d'une halocinese precice le long du faisceau de failles n 20-30. Ainsi au jurassique la region du dome de barrot serait limitee a l'ouest par rapport au bassin subalpin. La confrontation des donnees paleogeographiques mesozoiques d'une part, et des resultats geophysiques et structuraux d'autre part, nous incite a envisager l'existence d'une zone transformante a jeu dextre au jurassique
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Leroy, Marie. "Mécanismes de déformation post-rifting des marges passives : Exemple des marges péri-atlantiques et modélisation". Rennes 1, 2004. https://tel.archives-ouvertes.fr/tel-00008495.
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De nombreuses marges passives, et notamment celles de l'océan Atlantique, présentent des indices de déformation post-rift, caractérisée par de la surrection et du raccourcissement horizontal, qui se répercute sur la géométrie des systèmes sédimentaires. Différents mécanismes ont été envisagés dans la littérature pour expliquer ces déformations. La modélisation nous permet d'en tester certains. Le ridge-push, la tectonique régionale, l'influence des points-chauds, et de la rhéologie des marges, ont ainsi été testés grâce à des modèles analogiques et numériques. Il résulte des observations naturelles dans l'océan Atlantique et des modélisations, que la déformation récente des marges passives est liée à des associations différentes de mécanismes selon chaque marge. Cependant certains mécanismes pourraient favoriser ces déformations (ridge-push ou compression régionale, points chauds mis en place lors de leur formation ou postérieurement).
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Leroy, Marie. "Mécanismes de déformation post-rifting des marges passives : exemple des marges péri-atlantiques et modélisation /". Rennes : Géosciences-Rennes, 2005. http://catalogue.bnf.fr/ark:/12148/cb39998257g.
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Nadin, P. A. "Cretaceous-tertiary post-rift subsidence across the NE Atlantic margin : an analysis using quantitative 2-D and reverse stratigraphic modelling". Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283040.
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Papadimitriou, Nikolaos. "Geodynamics and synchronous filling of a rift type-basin evolved through compression tectonics (The western margin of the Levant Basin)". Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066540/document.
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La Méditerranée orientale doit sa complexité aux mouvements tectoniques des plaques Africaines, d’Arabie et d'Eurasie. Les récentes découvertes pétrolières du bassin Levantin (2009) renforcent la nécessité d’une approche combinée sismique/terrain pour comprendre l’évolution de son remplissage. L’intégration des données de sismique 2D et des données de terrain a permis de proposer des modèles conceptuels 3D qui, couplées aux données de puits, ont permis de définir les sources sédiementaires et les principales phases de remplissages correspondantes aux grands évènements géodynamiques. Ainsi l’évolution du bassin du Levan est marquée par la transition d’une sédimentation carbonate vers une sédimentation mixte (silicoclatisque/carbonaté) au cours du Crétacé. Seul le mont Ératosthène, situé sur une tête de bloc basculé hérité du rifting thétysien, conserve une sédimentation carbonatée superficielle jusqu’au Crétacé supérieur, liée à sa distance des sources silicoclastiques. Celui-ci présente 4 séquences de sédimentation carbonatée alternant superficielle et profonde: La fin du Jurassique moyen, le Crétacé inférieur, le Crétacé supérieur suivie et le Miocène. L'amorce de la collision Miocène en les plaques Eurasienne et Africaine coïncide avec le soulèvement d'Eratosthène avec une phase paroxysmique au cours du Miocène supérieur suivi par son basculement vers le nord en avant de l’ile de Chypre. Nous montrons que la collision a provoqué la formation de petits bassins au sud de Chypre ; un bassin piggyback (Polis Basin) et un bassin flexural (bassin de Limassol) ; contrôlés par la distribution des sédiments mésozoïquesThe Eastern Mediterranean owes its complex nature to the movement of Africa, Arabia and Eurasia. The recent gas discoveries in the Levant Basin (2009) provoked the necessity of necessity of conducting a combined (seismic and field) study to better understand the geological evolution of the Basin. The combination of geophysical and field data allows the conceptualization of onshore and, offshore 3D models in order to characterize the tectonostratigraphic evolution of this area and eventually trace the main sources and pathways that contributed to the infilling of the Levant Basin. The evolution of the Levant Basin is marked by the transition from a pure carbonate system to a mix system (carbonate /siliciclastic) during the Cenozoic. The Eratosthenes block corresponds to a fault block platform. Four major seismic sequences, characterized by periods of aggradation, retrogradation and progradation, punctuated by major unconformities and drowning surfaces have been recognized on the Eratosthenes Seamount. These periods are: the Late Jurassic; the Early Cretaceous, the Late Cretaceous and the Miocene. The initiation of the collision during the Miocene between the African and Eurasian plates coincides with the uplift of the Eratosthenes Seamount with a peak during the upper Miocene (pre-Messinian Salinity Crisis) followed by its northward tilting under Cyprus thrusting. We show that the collision of the two plates caused the formation of small basins in southern part of Cyprus; a piggyback basin (Polis), and a flexural basin (Limassol) that were controlled by the different substratum of the Mesozoic sediments
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MacLachlan, Kate. "The Wild Bight Group, Newfoundland Appalachians : a composite early to middle-Ordovician ensimatic arc and continental margin arc-arc rift basin /". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0011/NQ36208.pdf.
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Thomas, Bruno. "Marges continentales sardes : géologie, géodynamique". Paris 6, 1986. http://www.theses.fr/1986PA066307.
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La richesse géologique des marges sardes apporte d'importantes informations qui permettent d'affiner : les étapes de l'expansion et du fractionnement d'un arc complexe; la cinématique du rapprochement relatif des plaques européenne, apulienne et africaine; la succession des évènements tectoniques en particulier le contact avec la collision entre les lithosphères continentales et les éléments d'un arc dispersé.
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Bidault, Marie. "Structure des croûtes profondes à déformation syn-magmatique en contexte extensif". Thesis, Brest, 2019. http://www.theses.fr/2019BRES0021/document.
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Les profils de sismique réflexion de Marges Passives Volcaniques imagent une croûte inférieure réflective formée de deux domaines distincts. Ces réflecteurs sont interprétés comme des intrusions mafiques associées à la formation de la marge. Les observations géophysiques ne permettent pas de comprendre les conséquences associées à la mise en place de ces magmas sur la rhéologie et la déformation effective de la croûte inférieure des marges volcaniques. Cette thèse explore deux exemples géologiques de croûte inférieure à l’affleurement qui ont été affectés par d’importants volumes magmatiques pendant leur histoire extensive : la Zone d’Ivrée (Alpes italiennes) et la province de Seiland (Calédonides finmarkiennes). Une étude approfondie de terrain, associée à des analyses géochimiques et isotopiques ainsi qu’à des expériences de déformation en Presse Paterson permet, (1) de définir la structure synthétique finie d’une croûte inférieure extensive affectée par un ou plusieurs épisodes magmatiques intenses et d'identifier dans la Zone d’Ivrée une croûte moyenne ductile, dans laquelle s’enracinent les failles de la croûte supérieure, (2) de montrer l’évolution de la rhéologie et de la déformation ductile de la croûte inférieure relativement à la mise en place des magmas (3) de caractériser à partir de Seiland l’interface croûte manteau dans un contexte d’extension synmagmatisme mafique. L’ensemble des résultats montre la complexité des relations, à la fois structurales, spatiales et temporelles, entre les magmas et roches mafiques et la déformation en extension dans la croûte inférieureSeismic reflection profiles of Volcanic Passive Margins show a two-domain reflective lower crust. The particular reflectors are interpreted as mafic intrusions associated to the margin evolution.From those geophysical observations it is not possible to understand the consequences of mafic magma emplacement on the rheology and effective deformation of volcanic margins lower crust. This thesis explores two geologic examples of outcropping lower crusts affected by important volumes of magma during their extensional story: the Ivrea Zone (Italian Alps) and Seiland (Finmarkian Caledonides). An important field study associated to geochemical and isotopic analyses, and to Patersonapparatus deformation experiences led to (1) define a synthetic structure of an extensional lower crust affected by one or more major magmatic events and to indentify a ductile middle crust in the Ivrea Zone where roots the upper crust faults, (2) show the rheologic and deformation evolution of the lower crust in relation to magma emplacement timing, (3) characterize, from Seiland observations, the crustmantle interface in an extensional System. The whole study shows the complexity of the temporal, spatial and structural relationships between mafic rocks (as magma and as crystallised rock) and extensional deformation in the lower crust
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Abdelmalak, Mohamed Mansour. "Transition spatio-temporelle entre rift sédimentaire et marge passive volcanique : l’exemple de la baie de Baffin, Centre Ouest Groenland". Le Mans, 2010. http://cyberdoc.univ-lemans.fr/theses/2010/2010LEMA1030.pdf.
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Les marges passives volcaniques permettent d’étudier les mécanismes de rupture de la lithosphère continentale en présence d’un manteau anormalement chaud. Alors que ces marges ne sont généralement étudiées qu’à partir des moyens de prospection géophysique, les côtes du Groenland (Province Magmatique Nord-Atlantique) présentent un exemple onshore des parties proximales de ce type de marges. La thèse présentée se focalise sur l’évolution structurale et thermique de ces marges, en intégrant l’extension et le développement des bassins sédimentaires pré-magmatiques. La marge SE de la Baie de Baffin (Centre Ouest Groenland) expose un rift sédimentaire Crétacé qui a évolué en marge passive volcanique, lors de la rupture lithosphérique entre le Groenland et la plaque Nord Américaine à l’Eocène. Tous les contacts et les structures tectoniques sont visibles à terre, en coupe et en plan sur une zone d’affleurement d’environ 200x300 km : contact socle /faille bordière du rift, recouvrement et cachetage des formations sédimentaires par les formations volcaniques, développement d’un prisme de type SDR pendant le break–up Eocène. Le développement du système sédimentaire Crétacé/ Paléocène inférieur est caractérisé par la succession de deux épisodes de rifting séparés par un épisode de subsidence thermique. Le premier épisode, qui date du Crétacé inférieur réactive des structures du socle de direction WNW-ESE à NW-SE. Le deuxième épisode d’extension, d’âge Crétacé supérieur, est caractérisé par des failles subméridiennes et une extension générale E-W. Cet épisode tectonique précède le magmatisme paléogène. La transition du stade « rift sédimentaire » au stade « marge volcanique » est caractérisée par la focalisation de la déformation vers l’ouest (i. E. Vers le domaine océanique) avec une flexuration syn-magmatique de la croûte et une formation d’un prisme de SDR interne dont on présente la structure 3D. Le développement de ce prisme est contrôlé par un détachement à pendage vers le continent. L’extension au niveau de la marge est généralement perpendiculaire à la direction de la flexure à l’exception de la zone de Nuussuaq qui représente un segment d’ouverture oblique. Une direction d’extension postérieure à la flexure, syn-magmatique et subméridienne est également identifiée. Cette extension, datée du début de l’Eocène (C24), coïncide avec le changement de direction d’ouverture entre la plaque Groenland et la plaque Nord Américaine et le début de l’océanisation dans la Baie de Baffin. Afin de contraindre l’évolution thermique du bassin sédimentaire avant et pendant le magmatisme, une étude couplée de RockEval de réflectance de la vitrinite et de minéralogie magnétique est entreprise dans les formations argileuses de la marge. La matière organique identifiée est de type III et on met en évidence un gradient de maturation de l’est vers l’ouest, en bon accord avec la paléogéographie du bassin sédimentaire. L’aimantation rémanente isotherme (IRM) à haute température (HT) et à basse température (BT) ainsi que l’étude de la susceptibilité magnétique d’échantillons d’argilites, montre l’existence de phases magnétiques particulières, comme la goethite, la greigite, la magnétite et la pyrrhotite. Ces minéraux magnétiques permettent de contraindre l’évolution thermique du bassin en association avec les données de Rock-Eval et de réflectance de la vitrinite. Finalement, nous présentons un modèle thermo-structural de ce type de marge qui est confronté aux modèles de la marge offshore de Vøring au large de Norvège, marge analogue à fort potentiel en hydrocarburesLithosphere extension and consecutive breakup above a melting mantle lead to the formation of volcanic passive margins. All volcanic margins developed in continental areas subjected to long-term extension, leading to the formation of sedimentary basins. While these volcanic margins are usually offshore and are studied only by geophysical methods, the Greenland coasts offer an onshore proximal part of volcanic margins. The objective of this work is to the study of the spatio-temporal transition between a sedimentary basin to a volcanic-type passive margin. It considers the case of the geological example of the SE Baffin Bay area (the central west Greenland margin), especially its structural and thermal evolution. The study area is characterised by a rifted sedimentary basin which evolves to a volcanic margin associated with the Eocene lithosphere breakup between the Greenland plate and North America. All the structures can be observed in an outcropping area of about 200x 300 km: the rift border faults along the basement, the tectonized sedimentary pile, the overlapping and sealing of the sedimentary basin by Palaeocene volcanic traps and the Eocene inner SDR whose development is coeval with the lithosphere breakup. The development of the Cretaceous/Lower Paleocene sedimentary basin is characterized by two successive rifting episodes separated by a thermal subsidence period. The first rifting episode was initiated in the lower Cretaceous following ~N020E extension. This episode is poorly constrained and seems to be controlled by the inheritage structure of the Greenland Precambrian basement. The second rifting episode of Late Cretaceous presents an E-W to N060 extensional trend. This episode predates the extrusion of Paleocene hyalloclastites in a residual lacustrine basin. The transition from a sedimentary rifting 'stage' to a volcanic margin stage is characterized by the concentration of deformation to the west (i. E. Towards the oceanic crust). This syn-magmatic rifting episode is characterized by the oceanward flexure of the thick piles of Paleogene basalts and the onset formation of Seaward dipping reflectors (SDR) which establish the 3D structure. The development of the SDR is accommodated by arrays of continentward dipping detachment faults localized in the continent-ocean transition area. The syn-magmatic extensional trend is generally orthogonal to the margin flexure. This stage is followed by a more homogenous N-S syn-magmatic extension, which presents an Eocene (C24) age. This extension is the result of the probable earliest stage of oceanization in the Baffin Bay and then a global plate reorganisation in the North Atlantic area. A combined study of RockEval, vitrinite reflectance and magnetic mineralogy is performed from claystones samples collected in the area to assess the thermal evolution of sedimentary basin before and during magmatism. The RockEval and vitrinite reflectance indicated a predominance of type III organic matter and showed an oceanward increasing maturity, as a consequence of the increasing burial depth. The study of the isothermal remnant magnetization (IRM) at high and low temperatures and the study of magnetic susceptibility of claystones showed the existence of special magnetic assemblages with increasing burial. This indicator was used to constrain the thermal evolution combined to data from Rock-Eval and vitrinite reflectance. The results show that the sediments are immature to early mature, implying a moderate impact of local magmatic intrusions in the maturation of organic matter. A thermo-structural model of the west Greenland margin is also presented and completed by the structural study of the analogue Vøring margin
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Campanile, Daniel J. "The post-breakup evolution of the western Indian high-elevation passive margin". Thesis, Connect to e-thesis, 2007. http://theses.gla.ac.uk/38/.
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Thesis (Ph.D.) - University of Glasgow, 2007.Ph.D. thesis submitted to the Department of Geographical and Earth Sciences, Physical Sciences Faculty, University of Glasgow, 2007. Includes bibliographical references. Print version also available.
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Ye, Jing. "Evolution topographique, tectonique et sédimentaire syn- à post-rift de la marge transformante ouest africaine". Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30218/document.
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Cette thèse présente la première étude Source-to-Sink de la marge Atlantique Equatoriale africaine au Méso-Cénozoïque. Nous avons dans un premier temps produit, à partir d'une nouvelle méthode intégrant les limites d'érosion des dépôts préservés dans les bassins et leur extension initiale minimum, une nouvelle reconstruction paléogéographique et structurale couplant pour la première fois le continent ouest africain et l'Atlantique Equatoriale au cours du Méso-Cénozoïque. Ceci nous permet de suivre l'évolution depuis 200 Ma des domaines en érosion (sources) et en sédimentation (puits) à l'échelle continentale. Nous montrons en particulier qu'au Crétacé supérieur la zone correspondait à un grand bassin intracratonique Saharien qui exportaient ses sédiments à la fois vers la Téthys et vers l'Atlantique Equatoriale. La fragmentation de ce bassin a eu lieu à l'Oligocène par le soulèvement du bouclier du Hoggar qui a isolé les petits dépôt-centres résiduels actuels. Le développement de cette topographie particulière est issu de la superposition de différentes longueurs d'onde de déformation à l'échelle continentale combinant les bourrelets marginaux longeant la marge équatoriale et un bombement de type " point chaud ".Nous avons ensuite caractérisé, à partir de l'interprétation des données sismiques et des puits, la segmentation de la marge continentale équatoriale en segments transformants et divergents et l'architecture stratigraphique post-rift du prisme stratigraphique associée au Crétacé Supérieur. Nous montrons que les parties proximales (dépôts de plateforme et pente continentale) des prismes stratigraphiques du Crétacé Supérieur ne sont préservés que le long des segments divergents de la marge, et pas le long des segments transformants. Nous interprétons cette différence de préservation comme résultant de mouvements verticaux post-rift plus importants dans les domaines proximaux des segments transformants empêchant la préservation des termes proximaux des systèmes sédimentaires. La caractérisation des architectures stratigraphiques post-rifts a ensuite permis la quantification des volumes sédimentaires préservés dans ces bassins de marges passives. En parallèle, de nouvelles données de thermochronologie basse-température (AFTA et (U-Th-Sm/He sur apatite) acquises à l'Université de Glasgow sur les échantillons de trois profils perpendiculaires à la marge équatoriale ont permis de quantifier l'histoire de l'érosion et les volumes dénudés sur le domaine continental au cours du Méso-Cénozoïque. Ces données montrent que le seul événement thermique majeur enregistré correspond au refroidissement lié à la dénudation d'une topographie syn-rift le long de la marge. Le bilan d'érosion et d'accumulation montre que les ordres de grandeur des volumes dénudés et accumulés sont comparables à l'échelle de la marge équatoriale au cours du Méso-Cénozoïque. Certaines périodes (Crétacé Supérieur et depuis le Miocène Supérieur), montrent cependant un excès d'accumulation qui pourrait être associé à la remobilisation de sédiments précédemment stockés dans des bassins intracontinentaux ou sur la plateforme de la margeThis PhD thesis presents the first source-to-sink study of the African Atlantic Equatorial margin. We established new Meso-Cenozoic paleogeographic and structural reconstructions, integrating the West African sub-continent and the Equatorial Atlantic Ocean, based on a new mapping method defining both erosion limits of preserved deposits and their minimum original extension. We show the evolution over 200 Myrs of the eroding (sources) and accumulating domains (sinks) at continental scale. We demonstrate in particular that during the Cretaceous, a large Saharan intracratonic basin was exporting sediments toward both the Tethys and the future Atlantic Equatorial Ocean. The fragmentation of this basin occurred in the Oligocene, by the growth of the Hoggar swell that isolated the present-day small residual depot-centers. The development of this specific "basin and swell" topography results from the superimposition of various deformation wavelength at continental scale combining a marginal upwarp along the equatorial margin and a hot spot swell. We then characterized, from the interpretation of seismic data and well logs, the segmentation of the Equatorial Atlantic passive margin and the stratigraphic architecture of the post-rift Upper Cretaceous sedimentary wedge. We show that the proximal parts of the Late Cretaceous sedimentary wedge are only preserved along divergent segments of the margin and not along transform segments. We interpret this differential preservation as the result of a greater uplift, during the early post-rift, in the proximal parts of the transform segments preventing the preservation of the proximal terms of the sedimentary systems. The transform segments are associated with narrow necking zone, resulting in greater flexural uplift than divergent segments showing wider necking zones, in particular during the early post-rift. The characterization of the stratigraphic architecture of the post-rift sedimentary wedge then allowed for the quantification of accumulation history in the passive margin basins. New low-temperature thermochronological data (AFTA and Apatite (U-Th-Sm)/He) acquired at the University of Glasgow on the samples of three regional transects perpendicular to the margin allowed for the quantification of the denudation history and eroded volume on the continental domain. These data shows that the major thermal event recorded by those samples is the cooling phase related to the erosion of a rift-related topography along the margin. Erosion and accumulation budgets fall within the same order of magnitude. During some given periods (Late Cretaceous and since the Late Miocene), excess in accumulation may be associated with the reworking of sediments previously stored within intracontinental basins or on the shelf of the margin
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Cogné, Nathan. "Réactivation post-rift de la marge sud-est du Brésil". Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00739050.
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La marge du sud-est du Brésil est une marge passive élevée présentant des évidences d'activité magmatique et tectonique post-rift (intrusions alcalines et bassins sédimentaires). Nous avons mené une étude structurale et de thermochronologie (traces de fission et U-Th/He sur apatite) pour contraindre les âges, l'amplitude, les directions de contraintes et les causes de ces réactivations. La modélisation des données thermochronologiques nous a permis de mettre en évidence deux phases d'exhumation généralisée sur la région au Crétacé Supérieur et au Néogène. Une troisième phase durant le Paléogène est concentrée le long des bassins tertiaires. Au total, depuis la zone côtière jusqu'à la Serra da Mantiqueira, l'exhumation post-rift atteint 4.5 km. Une étude des profils sismiques du bassin de Taubaté, et des données d'affleurement a montré que les bassins tertiaires se formaient en transtension senestre au Paléogène, avec des contraintes compressives orientées SW-NE puis étaient réactivés en transpression dextre durant le Néogène sous l'effet de contraintes compressives E-W. Les âges, comme la cinématique des réactivations sont compatibles avec ceux inférés pour d'autres zones de la plaque sud-américaine ainsi qu'avec la cinématique de la convergence Nazca-Amérique du Sud. Nous avons donc conclu qu'un état compressif de l'ensemble de la plaque sud-américaine, sous l'effet des forces de ridge-push et de traction mantellique, était responsable de la réactivation des zones de faiblesses héritées, et provoquait les différentes phases de réactivation de la marge sud-est du Brésil, provoquant sa surrection et façonnant ainsi la topographie que nous connaissons aujourd'hui.
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Ndong, Ondo Simplice Marin. "Interaction entre la tectonique gravitaire extensive et la sédimentation sur la marge passive sud-gabonaise au cours de l'albo-turonien : application sur les structures gravitaires extensives kilométriques". Dijon, 2002. http://www.theses.fr/2002DIJOS036.
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MAGALHÃES, José Ricardo Gonçalves. "Compartimentação tectono-sedimentar da Bacia da Paraíba, a partir da integração de métodos potenciais e interpretação sísmica de dados OFFSHORE". Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/17212.
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Vários trabalhos têm tentado abordar a evolução das margens conjugadas do Atlântico, incluindo o nordeste do Brasil e o oeste da África. Entretanto, o avanço de pesquisas anteriores tem sido dificultado em razão da falta de dados na região marginal da porção oriental do nordeste do Brasil, principalmente na área inserida entre a Zona de Cisalhamento de Pernambuco e o Alto de Touros. Este fato tem imposto limitações ao desenvolvimento de modelos regionais sobre a evolução geotectônica e paleogeográfica desta região, assim como na correlação com sua contraparte na África. Nesta dissertação é apresentada uma investigação realizada com base em dados gravimétricos, magnéticos e sísmicos regionais. Os resultados mostraram que esta região representa um alto do embasamento com a orientação regional das principais estruturas tectônicas (ENE-WSW), ortogonais as estruturas desenvolvidas durante o processo de abertura das bacias da Paraíba e da Plataforma de Natal (NNE-SSW e NNW-SSE). Sobre o embasamento continental formou-se uma plataforma estreita com uma cobertura sedimentar pouco espessa (0,8-2,5 km) e uma quebra abrupta da plataforma, criando uma vasta zona de bypass através do talude. A análise de uma seção sísmica profunda revelou que a crosta continental afinada (crosta transicional) representa uma estreita zona e que o limite crosta continental-oceânica (COB) está localizado a aproximadamente 100 km a leste da atual linha de costa, na Bacia da Paraíba, e a 70 km, na Bacia da Plataforma de Natal. A modelagem geofísica, integrada com a interpretação sísmica, indica que esta região é caracterizada por um afinamento abrupto da crosta continental, com a consequente ascensão súbita da Moho. Também há evidências da existência de uma zona de crosta continental extremamente afinada, a qual foi interpretada como crosta proto-oceânica. Estes novos dados demonstram que esta área apresenta fortes similaridades com margens rifteadas não vulcânicas ou pobres em magma.
Several studies have tried to address the evolution of the Atlantic conjugate margins, including Northeast Brazil and West Africa. However, past research advances has been hindered by a lack of data for the marginal region in the eastern portion of northeastern Brazil, extending from the Pernambuco Shear Zone to the Touros High. This situation has imposed serious limitations on the development of a regional view of the geotectonic and paleogeographic evolution of this area and on correlations with regional counterparts in Africa. Here, we present an investigation using regional gravimetric, magnetic and seismic data. The results show that this region represents a basement high with regional orientation of tectonic structures (ENE-WSW) orthogonal at structures developed during the open processes of the Paraíba and Natal Platform Basins (NNE-SSW and NNW-SSE). The continental basement forming a narrow platform with a thin sedimentary cover (0.8-2.5 km) and an abrupt shelf break, which created a large bypass zone towards the slope. The analysis of a deep seismic section revealed that thinned continental crust (transitional crust) occupies a narrow zone and that the continental-oceanic boundary (COB) is located approximately 100 km to the east of the present coastline, at Paraíba Basin, and 70 km, at Natal Platform Basin. Geophysical modeling integrated with interpretation of the seismic data suggests that this region is characterized by an abrupt thinning of continental crust, with an accompanying sudden rise of the Moho. There are also indications for the existence of a zone of extremely thinned continental crust, which was interpreted as protooceanic crust. Our findings suggest that the study area shows strong similarities to nonvolcanic or magma-poor rifted margins.
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Miller, Nathaniel Clark. "Evolution of oceanic margins : rifting in the Gulf of California and sediment diapirism and mantle hydration during subduction". Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82316.
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Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2013.Cataloged from PDF version of thesis.
Includes bibliographical references.
This thesis investigates three processes that control the evolution of oceanic margins. Chapter 2 presents seismic images of a ~2-km-thick evaporite body in Guaymas Basin, central Gulf of California. In rifts, evaporites form under conditions unique to the latest stages of continental rupture, and the presence, age, thickness, and shape place new constraints on the history of early rifting there. Chapter 3 presents numerical experiments that show that diapirs can form in sediments on the down-going plate in subduction zones and rise into the mantle wedge, delivering the sedimentary component widely observed in arc magmas. Chapter 4 presents measurements of seismic anisotropy from wide-angle, active-source data from the Middle America Trench that address the hypothesis that the upper mantle is hydrated by seawater flowing along outer-rise normal faults. These measurements indicate that the upper mantle is ~1.57 to 6.89% anisotropic, and this anisotropy can be attributed to bending-related faulting and an inherited mantle fabric. Accounting for anisotropy reduces previous estimates for the amount of water stored in the upper mantle of the down-going plate from ~2.5 to 1.5 wt%, a significant change in subduction zone water budgets.
by Nathaniel Clark Miller.
Ph.D.
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Winter, Lawrence Stephen. "The genesis of ‘giant’ copper-zinc-gold-silver volcanogenic massive sulphide deposits at Tambogrande, Perú : age, tectonic setting, paleomorphology, lithogeochemistry, and radiogenic isotopes". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/773.
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The ‘giant’ Tambogrande volcanogenic massive sulphide (VMS) deposits within the Cretaceous Lancones basin of northwestern Perú are some of the largest Cu-Zn-Au-Ag-bearing massive sulphide deposits known. Limited research has been done on these deposits, hence the ore forming setting in which they developed and the key criteria that permitted such anomalous accumulation of base-metal sulphides are not understood.
Based on field relationships in the host volcanic rocks and U-Pb geochronology, the deposits formed during the early stages of arc development in the latest Early Cretaceous and were related to an extensional and arc-rift phase (~105-100 Ma, phase 1). During this time, bimodal, primitive basalt-dominant volcanic rocks were erupted in a relatively deep marginal basin. Phase 1 rhyolite is tholeiitic, M-type, and considered to have formed from relatively high temperature, small batch magmas. The high heat flow and extensional setting extant during the initial stages of arc development were essential components for forming a VMS hydrothermal system. The subsequent phase 2 (~99-91 Ma) volcanic sequence comprises more evolved mafic rocks and similar, but more depleted, felsic rocks erupted in a relatively shallow marine setting. Phase 2 is interpreted to represent late-stage arc volcanism during a waning extensional regime and marked the transition to contractional tectonism.
The Tambogrande deposits are particularly unusual amongst the ‘giant’ class of VMS deposits in that deposition largely occurred as seafloor mound-type and not by replacement of existing strata. Paleomorphology of the local depositional setting was defined by seafloor depressions controlled by syn-volcanic faults and rhyolitic volcanism. The depressions were the main controls on distribution and geometry of the deposits and, due to inherently confined hydrothermal venting, enhanced the efficiency of sulphide deposition.
Geochemical and radiogenic isotope data indicate that the rhyolites in the VMS deposits were high temperature partial melts of the juvenile arc crust that had inherited the isotopic signatures of continental crust. Moreover, Pb isotope data suggest the metal budget was sourced almost wholly from mafic volcanic strata. Therefore, unlike the implications of many conventional models, the felsic volcanic rocks at Tambogrande are interpreted to have only played a passive role in VMS formation.
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Allard, Patrick. "Géochimie isotopique et origine de l'eau, du carbone et du soufre dans les gaz volcaniques zones de Rift, marges continentales et arcs insulaires". Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375955010.
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Lovecchio, Juan Pablo. "Seismic stratigraphy of the offshore basins of Argentina : characterization and modeling of the South Atlantic passive margin dynamics". Electronic Thesis or Diss., Sorbonne université, 2018. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2018SORUS506.pdf.
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Ce mémoire traite de la formation et de l'évolution des bassins de la marge Atlantique argentine. Trois stades de rifting superposés ont été identifiés dans les bassins des Malvinas et de Colorado/Salado. Le premier événement de rifting est associé à la réactivation extensive, durant le Trias tardif, des chevauchements paléozoïques de la phase de Ventania-Cape. Un deuxième stade de rifting (Jurassique inférieur / moyen) a induit les failles contrôlant les principaux dépocentres et intersectant les structures plus anciennes. Finalement, l’extension du Crétacé inférieur liée à l’ouverture de l’Atlantique Sud s’est concentrée en périphérie de la marge continentale actuelle et a abouti à la mise en place de SDRs. L’évolution du bassin Malvinas a été caractérisée d’un point de vue sismique. Des nouveaux âges zircon U-Pb contraignent le rifting au Jurassique. Le nouveau modèle de rupture du Gondwana présenté ici met l'accent sur l'évolution des bassins mésozoïques péri-atlantiques. L’évolution post-rupture de la marge Atlantique argentine a également été étudiée via l’interprétation sismique et la caractérisation stratigraphique. Après la rupture Hauterivien / Barrémien, trois étapes d'évolution de la marge ont été identifiées. Le Crétacé est marqué par la subsidence thermique des principaux dépocentres. La marge devient une plate-forme continentale unique après la transgression régionale Maastrichtienne-Danienne. Le stade d’expansion du Paléogène est caractérisé par un affaissement et un apport sédimentaire centré au nord dans la région de Salado, tandis que le stade d’expansion du Néogène se caractérise par un comportement cylindrique de l’ensemble de la marge et par l’influence notable des courants de contourThis work is focused on basin formation and evolution in the Argentinean South Atlantic Margin and the Mesozoic breakup of SW Gondwana. Rifting evolution was studied in the Malvinas and Colorado/Salado basins. Three superimposed rifting events were identified in the latter. The first rifting event is associated with the Late Triassic extensional reactivation of Late Paleozoic thrusts of the Ventania-Cape fold belt. A second and main rifting stage (Early-Middle Jurassic) is related to faults forming the main depocenters and intersecting the older structures. Finally, Early Cretaceous extension linked to the opening of the South Atlantic Ocean focused on the outer continental fringe and produced emplacement of SDRs. The rifting evolution of the Malvinas basin was seismically characterized. New zircon U-Pb ages constrain rifting in the Jurassic. A new model for Gondwana breakup is presented with focus on the evolution of the Mesozoic peri-Atlantic basins. The post-breakup evolution of the Argentinean South Atlantic margin was also studied via seismic interpretation and stratigraphic characterization. Three stages of drift evolution were identified. After the Hauterivian/Barremian breakup, the Cretaceous drift unit is conditioned by the thermal subsidence over the main depocenters. Only after the Maastrichtian-Danian regional transgression, the margin becomes a single continental platform. The Paleogene drift stage is characterized by subsidence and sedimentary input centered in the Salado area, while the Neogene drift stage is characterized by a cylindrical behavior and the remarkable influence of contour currents
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Bulois, Cédric. "Marges polyriftées : réactivations et conditions aux limites. Exemples de la Mer de Corail (Papouasie Nouvelle Guinée) et du Bassin de Porcupine (Irlande)". Thesis, Brest, 2016. http://www.theses.fr/2016BRES0106.
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Cette étude documente la succession de phases de rift qui se sont formées le long d'une marge continentale dont l'évolution géologique a été particulièrement longue. Ce type d'évolution géologique est bien admise dans la littérature mais reste encore peu comprise en terme de processus géologiques. Ici, il est spécifiquement étudié comment ce type de rifts peut évoluer au cours du temps et il est tout particulièrement mis en évidence les processus de réactivation de failles et la formation des éléments géologiques associés dans l'évolution des bassins en extension. Cette étude résume les résultats principaux de deux projets de recherche menés sur(1) le Bassin de Porcupine (offshore irlandais) qui s'est formé pendant la propagation du système de rift nord-atlantique et (2) la région de la Mer de Corail (Papouasie Nouvelle Guinée) dont l'évolution en contexte de supra-subduction est liée à l'affrontement des plaques Pacifique et Australie. Ces deux projets de recherche discutent spécifiquement de l'enregistrement sédimentaire et de l'évolution des failles à partir de données sismiques corrélées à des données de puits, de magnétisme ou de gravimétrie.Les deux bassins ont évolué en bordure d'orogènes depuis le Paléozoïque supérieur. Il est démontré que l'extension s'est initiée au long de structures anciennes qui ont été réactivées lors de l'étalement orogénique mis en évidence par la migration de dépocentres. L'extension s'est ensuite développée de façon discontinue au cours de divers épisodes extensifs pulsés. Les premiers épisodes montrent en général des bassins étroits, plus ou moins discrets et qui sont remplis de dépôts continentaux qui passent progressivement à des environnements marins. L'extension est d'abord diffuse puis localisée le long de failles bordières qui accommodent l'ensemble de l'extension et le boudinage de la croûte. Au fur et à mesure que l'extension progresse, l'influence structurale de la croûte continentale diminue et la déformation évolue vers l'océan avant le stade ultime de déchirure continentale de façon très localisée. Le rifting se termine en général dès que les conditions aux limites changent, résultant en la production de bassins océaniques en propagateur qui sont transversaux aux bassins néoformés. Dans les marges classiques de type atlantique (p.ex. Bassin de Porcupine), ceci est lié à la propagation de croûte océanique dans des bassins plus ou moins perpendiculaires tels que le Golfe deGascogne dont l'ouverture stoppe la déformation extensive. Dans les zones en supra-subduction (par ex. Mer de Corail), la fin de l'extension est plutôt liée à un changement dans la dynamique de subduction qui peut contrôler l'ensemble de la propagation de l'océanisation.Ainsi, il apparait que l'extension migre progressivement depuis une zone initiale en réactivant d'anciennes structures orogéniques quelles que soit les conditions géodynamiques initiales. Ici, il est proposé qu'une phase de déformation souligne un mégacycle extensif durant lequel des grabens individuels, des bassins riftés ou des systèmes de rifts se forment successivement et surimposent les uns aux autres. Chaque mégacycle peut se définir sédimentologiquement et tectoniquement. La surimposition montre en général une déformation qui évolue progressivement vers l'océan par la réactivation spécifique de structures pré-existantes.L'initiation de l'extension et le passage d'un mégacycle à un autre est en général lié par un changement des conditions aux limitesThis study documents the succession of rifting phases that evolve along continental margins of longstanding history. This type of evolution, well admitted in the literature, remains poorly understood in terms of geological processes. Herein, the way rifts evolve through is specifically studied to highlight the fault reactivation processes and the formation of associated geological elements during the evolution of extensional basins. This study summarises some principal results of two research projects focussing on (1) the Porcupine Basin (offshore Ireland) that formed from the North-Atlantic rift propagation and (2) the Coral Sea region (Papua New Guinea) which the evolution within a supra-subduction context links to the convergence of the Pacific and Australian lithospheric plates. These two research projects specifically discuss the sedimentary record and the faulting evolution from seismic data correlated to wells, magnetism and gravimetry.Both basins evolved from the Late Palaeozoic on sides of orogens since the Late Palaeozoic. It is demonstrated that extension initiated along old structures that were reactivated during a general orogenic collapse evidenced by migration of depocentres. Then, extension discontinuously developed during several rifting events that are usually internally pulsed. The first rift events are usually very narrow and discreet, and evolve in a continental domain. Deformation progressively passes to localized normal faulting implying that major bounding faults progressively accommodate the extension. As long as extension progresses, the influence of continental structures tend to decrease and the deformation evolves oceanward prior continental tear. Extension generally stops once boundary conditions change, resulting in oceanic crust that may propagate transversally (oceanic propagators).Along classical Atlantic-type margins (e.g. Porcupine Basin), this links to the propagation of the oceanic crust but internal crosscutting oceanic basins (e.g. Bay of Biscay) stop the deformation prior to seafloor spreading that form the overall oceanic crust.In supra-subduction zones (e.g. Coral Sea), it is rather related to a change in the dynamics of the subduction which may control the overall direction of the spreading propagation.Thus, extension migrates progressively away from the initial deformation core by reactivating pre-existing structures, whatever geodynamic conditions are but with a general decrease in the influence of old continental fabrics. Herein, it is proposed herein that a deformation phase expresses as an extensional megacycle during which graben, basins or rift settings develop successively and overprint the ones another. Each extensional megacycle may be defined sedimentologically and tectonically. Their overlap generally shows an oceanward migration which reactivates specific pre-existing structures. The initiation of extension and the evolution from a megacycle another is generally linked associated to a variation of the boundary conditions
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Arab, Mohamed. "Analyse des systèmes pétroliers de l'offshore algérien oriental : quantification, modélisation stratigraphique et thermique". Thesis, Brest, 2016. http://www.theses.fr/2016BRES0130/document.
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La marge algérienne est un domaine complexe, bordé au sud par les zones internes des Maghrébides (AlKaPeCa) qui chevauchent les zones externes telliennes vers le sud. La partie offshore de ce système constitue un bassin d‘arrière arc où s‘est déposée une série sédimentaire mio-pliocène reposant sur un substratum de nature et d‘origine variables spatialement. L'objectif de ce travail a consisté à analyser et modéliser le fonctionnement des systèmes pétroliers et à quantifier les volumes d‘hydrocarbures accumulés. Avant de procéder aux différentes modélisations numériques, stratigraphiques et thermiques, un modèle géologique conceptuel a été élaboré sur la base des données de géologie de terrain et de sismiques. La continuité terre- mer du socle kabyle a permis une extrapolation stratigraphique entre des formations oligo-miocènes en affleurement et les unités acoustiques définies dans le bassin offshore. L‘analyse tectonique dans les deux domaines a abouti à une évolution en trois phases : (1) syn-rift où le bassin a été ouvert en transtension à partir de l‘Oligocène supérieur-Aquitanien, (2) phase post-rift durant laquelle il y a eu le développement des bassins intra-arcs, la collision AlKaPeCa- Afrique et le magmatisme, (3) phase d‘inversion où la marge devient active essentiellement à partir du Quaternaire. En définissant l‘ensemble des éléments des systèmes pétroliers avec des incertitudes variables, la simulation du fonctionnement de ces derniers par modélisation de bassin 2D/3D a montré des possibilités d‘accumulation d‘huile et de gaz majoritairement près de la marge, entre 20 et 65 km de la côte avec un maximum de portée de 70 km dans le golfe de BejaiaThe Algerian margin is a complex domain, limited to the south by the Maghrebian internal zones (AlKaPeCa) that overthrust the external Tellian zones southward. The offshore part of this system constitutes a back-arc basin, where a mio-pliocene sedimentary series were deposited over a substratum of laterally variable origin and nature. The goal of the present work consisted in analyzing and modelling the petroleum system at work and calculating hydrocarbon volumes. Before proceeding to different numerical basin, stratigraphic and thermal modelling, a conceptual geological model is required and was performed based on field geological studies and stratigraphic and structural interpretations of the seismic profiles. The extension of the continental crust beyond the foot of the margin, allows determining a chronostratigraphic model by extrapolation of the outcroping oligo-miocene formations onshore to the acoustic pre-messinian units defined in the offshore basin. Besides, a tectonic analysis in both onshore and offshore domains gave rise to three main steps of evolution: (1) syn-rift phase where the basin was opened by transtension since Late Oligocene- Aquitanian, (2) post-rift phase in which intra-arc basins were developed, AlKaPeCa and Africa docked and magmatism activity took place, (3) inversion phase where the margin became active mainly since Quaternary times. After defining the different petroleum system elements taking into account variable uncertainties, the 2D/3D petroleum system model depicts possibilities of oil and gas accumulations mainly close to the margin, between 20 to 65 km from the coastline to the north with a maximum range of 70 km in the Bejaia Gulf
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Anka, Zahie. "Evolution de l'éventail sous-marin du Zai͏̈re (Congo) depuis le cretage : Intéraction avec la marge continentale du golfe de Guinée". Montpellier 2, 2004. http://www.theses.fr/2004MON20025.
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Dupont, Pierre-Luc. "Pétrologie et géochimie des ensembles magmatiques pharusien I et II, dans le rameau oriental de la chaîne pharusienne (Hoggar, Algérie) : Implications géodynamiques pour l'évolution d'une chaîne mobile au protérozoïque supérieur". Nancy 1, 1987. http://www.theses.fr/1987NAN10332.
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Au pharusien I, la série de timesselarsine révèle l'épanchement de basaltes, d'affinité transitionnelle a faiblement alcaline dont le site géodynamique serait celui d'un "rift" en domaine continental. Vient ensuite une série ultrabasique/basique dont le site le plus probable est celui d'arc insulaire ou de bassin marginal. Le troisième épisode est représenté par deux ensembles : un lié à un domaine de type arc insulaire, l'autre montrant une évolution vers une marge continentale active. Au pharusien II, la série d'anded est intrudée par des dolérites et des roches volcaniques en liaison avec un site de type arc insulaire. La série d'Irrellouchem est liée à un site d'arc insulaire ou de marge continentale active. Les données isotopiques du strontium obtenues sur ces deux séries impliquent une contribution mantellique importante. Le dernier épisode pharusien est représenté par les roches du batholite de Tin Tekadiouit
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Nirrengarten, Michael. "Modes de déformation et implications cinématiques des marges hyper-étirées : les exemples du sud de l'Atlantique Nord". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAH014/document.
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Les modes de déformation des systèmes de rift hyper-étirés pauvres en magma évoluent dans le temps et dans l’espace. Ainsi les structures et architectures observées varient le long d’une section en profondeur ainsi que sur une carte. Cette étude vise à caractériser les modes de déformation des systèmes hyper-étirés et leur propagation en utilisant les exemples du sud de l’Atlantique Nord. L’architecture de la terminaison de la croûte continentale a été comparée à la théorie du prisme critique de Coulomb car sa forme est prismatique, la déformation finale est cassante/frictionnelle et ce prisme glisse sur un décollement basal. Cette théorie met en évidence le comportement distinct des deux marges conjuguées. De plus, elle contraint l’architecture crustale, permet l’intégration des failles contre-régionales et explique la formation des blocs allochtones dans un modèle de failles en séquence. L’intégration des modes de déformation dans un modèle évolutif 3D impose un contexte cinématique fiable, ce qui n’est pas le cas de l’ouverture océanique du sud de l’Atlantique Nord. Ceci est dû à l’interprétation de l’anomalie J comme un isochrone. L’investigation de cette anomalie indique une formation polygénique et polyphasée incohérente avec un isochrone ou une limite de domaine. Ainsi l’anomalie J est inutilisable pour les reconstructions cinématiques. L’évolution de la déformation de rift a été analysée grâce à une nouvelle reconstruction cinématique du sud de l’Atlantique Nord. Il apparait alors que la déformation de la croûte continentale est segmentée alors que la propagation de la croûte océanique forme un V. L’approche développée dans cette thèse pose également de nouvelles questions géodynamiques quant à l’influence de l’héritage et l’effet des points tripleDeformation modes of magma-poor hyper-extended rift systems evolve through time and space. Hence the observed structures and architectures vary along a depth section as well as on a map. This study aims to characterize the deformation modes of hyper-extended systems and their propagation using the examples of the southern North Atlantic. The architecture of the continental crust termination has been compared to the critical Coulomb wedge theory because it has a wedge shape, the final deformation is brittle/frictional and this wedge is gliding over a basal detachment. This theory highlights the distinct behavior of the two conjugate margins. Moreover it constrains crustal architecture of the continental crust termination, integrates continentward dipping faults and explains the formation of extensional allochthons in a sequential faulting model. The integration of deformation modes in an evolving 3D model necessitates a reliable kinematic context, which is not the case for the opening of the southern North Atlantic Ocean. This is linked to the interpretation of the J-magnetic anomaly as an oceanic isochron. Re-investigations of this anomaly revealed its polygenic and polyphased formation, which is inconsistent for an oceanic isochrons or a domain boundary making it unusable for plate reconstruction. The evolution of rift deformation has been analyzed with a new plate reconstruction of the southern North Atlantic. It appears that the continental crust deformation is segmented whereas oceanic crust propagates in a V-shape. The approach developed in this thesis also asks new geodynamical questions on the influence of inheritance and the effect of triple junction
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Thinon, Isabelle. "Structure profonde de la Marge Nord Gascogne et du Bassin Armoricain". Phd thesis, Université de Bretagne occidentale - Brest, 1999. http://tel.archives-ouvertes.fr/tel-00605279.
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La formation et l'évolution de la Marge continentale passive Nord Gascogne et du Bassin Armoricain sont fortement liées à l'ouverture du golfe de Gascogne et à la formation des Pyrénées. L'étude des structures tectono-sédimentaires, calées aux forages profonds DSDP et pétroliers, ainsi que l'étude de leurs prolongements dans les domaines émergés adjacents (Bassin de Parentis et les bassins de la Manche), ont permis de montrer l'évolution spatio-temporelle de la couverture sédimentaire. Un polyphasage tectonique lors du rifting et deux phases compressives pyrénéennes ont été identifiés. Des événements tectono-sédimentaires catastrophiques auraient affectés la marge à la fin du rifting. Le Bassin Armoricain serait un bassin sédimentaire jeune, ayant toutes les caractéristiques structurales d'une zone de Transition Océan/Continent effondrée à la fin du rifting ou lors de l'initiation de l'accrétion océanique. L'étude des structures crustales a permis de connaître la géométrie de la marge : la distance domaine océanique/domaine continental non-aminci est constante le long de la marge ; l'amincissement crustal s'effectue exclusivement sous l'étroite pente continentale, inférieure à 50 km de large ; les blocs basculés, situés au pied de la pente, ont un rôle mineur dans les processus d'amincissement crustal. Les modèles géodynamiques actuels d'une marge passive n'expliquent pas la géométrie de la Marge Nord Gascogne. Or cette géométrie, similaire à celle du Bassin de Parentis, n'est pas atypique ; nous pensons que l'amincissement est induit par d'autre processus géodynamique que l'extension pure.
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Gharbi, Mohamed. "Relationship between the southern Atlas foreland and the eastern margin of Tunisia (Chotts-Gulf of Gabes) : tectono-sedimentary, fault kinematics and balanced cross section approaches". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4340/document.
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L'architecture structurale de l’avant-pays sud atlasique tunisien est caractérisée par un style tectonique mixte résultant de la réactivation de failles normales connectées avec le socle, de la mise en place de décollements dans la couverture sédimentaire ainsi que d’un diapirisme non négligeable. La géométrie et l’orientation des structures extensives préexistantes, issues du rifting Trias à Turonien, contrôlent la déformation de la couverture sédimentaire au cours des phases compressives d’âge fini-mésozoïque et cénozoïque. En effet, la marge tunisienne a enregistrée une longue période de rifting, de la fin du Permien-Trias jusqu’au Turonien. Une inversion tectonique s’est initiée probablement pendant le Crétacé supérieur. Les compressions tectoniques tertiaires se sont produites au cours de trois périodes: l’Eocène, le Mio-Pliocène et le Plio-Quaternaire. Notre étude montre une variation temporel du champ de contrainte régional, d’un régime tectonique compressif de direction NW-SE d’âge Mio-Pliocène à un régime tectonique compressif de direction N-S à NNE-SSW d’âge Quaternaire à l’actuel. Ce changement de régime tectonique a lieu, soit à la fin du Pliocène, soit au début du Quaternaire. Et une variation spatiale du champ de contrainte, de la compression (Domaine atlasique de la Tunisie) à la transtension (Golfe de Gabès), semble se faire progressivement du Nord vers le Sud-Est. Cette étude souligne le rôle prépondérant des failles profondes héritées et acquises au cours de l'évolution de la marge passive sud téthysienne. Dans ce domaine, la restauration de notre coupe équilibrée montre un raccourcissement modéré en surface de l’ordre de 8.1 km (~7,3%)The structural architecture of the Tunisian foreland consists in a mixed tectonic style with deep-seated basement faults, shallower décollements within sedimentary cover and salt diapirism. Structural geometry and orientation of the pre-existing Triassic-Turonian extensional structures controlled subsequent contractional deformation within the sedimentary cover. The rifting of the margin started in the late Permian–Triassic and continued up to the Turonian. From the inversion of the successive compressions, the development of ENE-trending thrust-related anticlines such as the Orbata and Chemsi structures are controlled by the reactivation of the inherited Mesozoic faults. Geologic data from this region indicate that the positive tectonic inversion occurred probably during Late Cretaceous period. The Cenozoic tectonic compressions in the southern Atlassic domain occurred during three periods: Late Eocene, Late Miocene and Plio-Quaternary. The Fault kinematic analysis reveals a temporal change in states of stress that occurred during the Late Cenozoic. A paleostress (Miocene-Pliocene) state is characterized by a regional compressional tectonic regime with a mean N134±09°E trending compressional axis (σ1). A modern (Quaternary to present-day) state of stress also corresponds to compressional tectonic regime with a regionally mean N05±10°E trending horizontal σ1. This study underlines the predominant role of inherited basement structures acquired during the evolution of the southern Tethyan margin, and their influence on the geometry of the Atlassic fold-and-thrust belt. At the southern Atlas of Tunisia our restoration shows a surface shortening of ~8.1 km (~7.3%)
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Vaillant, Pascal. "L'extrémité occidentale de la marge nord Gascogne : contexte stratigraphique, structural et cinématique, implications géodynamiques". Brest, 1988. http://www.theses.fr/1988BRES2026.
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Geologie marine: bathymetrie, sismique, draguages, carottages, plongees, forages de la region situee dans le prolongement de la bretagne et de la cornouaille britannique. Les resultats confrontes aux traits geologiques des domaines emerges voisins permettent de reconstituer les domaines avant l'ouverture de l'atlantique nord. En tenant compte des contraintes cinematiques, un essai d'evolution tectonique est propose
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Rosa, Alessandro La. "Strain partitioning between border faults and axial magmatic segments in the Afar Rift". Doctoral thesis, 2021. http://hdl.handle.net/2158/1234394.
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Continental break-up is a key stage of the rifting process as it marks the transition to ocean seafloor spreading. Predictive models of the rift-to-seafloor spreading transition suggest that, during incipient continental break-up, the rift margins deactivate and extension focuses at the rift axis along a series of en-echelon magmatic segments which are offset by either transform or non-transform faults. However, how strain is partitioned between the rift margins and axial magmatic segments during the last phases of the rifting process remains poorly understood. Furthermore, how and when transform and non-transform offsets form during the rifting process is still unclear. Northern Afar, in the East African Rift System, is the ideal place to address these open questions as it shows these processes occurring during the final stages of continental rifting exposed at surface. In this thesis, I adopted a multi-disciplinary approach based on InSAR, seismicity and structural analyses to investigated the tectonic deformation and the fault kinematics at the offset between the two axial magmatic segments of Erta Ale and Tat’Ali (Afrera Plain) and also along the North-Western Afar Margin.
The results show that the Afrera Plain is an active rift-linkage zone characterized by en-echelon, oblique, left-lateral faults striking in a ~NS direction. The structural architecture of the Afrera Plain is characterized by dominant East-dipping faults at the center and dominant West-dipping faults at the eastern tip, close to the Tat’ Ali segment. Such structural architecture is consistent with a kinematic model of rift-linkage where Erta Ale and Tat’ Ali segments interact trough a right-lateral transfer zone characterized by en-echelon oblique faults, striking in a ~NS-direction. Furthermore, InSAR time-series and models, combined with seismic data, have revealed great variability in the fault behavior. Faults at the center of the Afrera Plain are characterized by dominant stick-slip faulting with episodic slip events accompanied by ML ≥ 5 earthquakes. Conversely, a more complex fault behavior encompassing creep, micro-seismicity and episodic slip characterize the tips of the linkage zone. Such heterogenous fault behavior could be likely influenced by the high heat flows and the strong hydrothermal circulation at the Afrera Plain. Intense seismicity also characterizes the North-Western Afar Margin. Here ongoing tectonic extension along active border faults generate moderate seismicity with several Mw > 5 earthquakes occurred in the past decades. Recently, a ML 5.3 seismic sequence occurred in March-April 2018 rupturing the deep portion (15-30 km) of crustal border faults. The analysis of focal mechanism and relocated seismicity shows that slip occurred along major West-dipping faults and minor conjugate East-dipping faults. The fault kinematics has dominant normal component associated with both minor left- and right-later components. Deep seismicity in the area is focused below the Dergaha marginal graben where there is geophysical evidence of partial melt in the lower crust. Such observations suggest that deep seismicity along the North-Western Afar Margin could be triggered by fluids migration in the lower crust associated with magmatic processes. Conversely, seismicity outside the Dergaha graben is shallower (< 15 km) and likely associated to brittle faulting in the upper crust. The results of this thesis provide one the few direct observations of the tectonic processes occurring at the interaction between two magmatic segments in Afar. Furthermore, they provide new contributions towards the understanding of the kinematic of rift margins in Afar during incipient continental break-up suggesting that fluid migration in the crust may play a role in influencing the fault activity along the North-Western Afar Margin.
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Scott, Deborah Lee. "Oblique lithospheric extension : a comparative analysis of the East African rift and some Australian margins". Phd thesis, 1994. http://hdl.handle.net/1885/140502.
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Kinney, Sean Thomas. "Re-evaluating the timescale of rift and post-rift magmatism on the Eastern North American Margin via zircon U-Pb geochronology". Thesis, 2021. https://doi.org/10.7916/d8-hwtn-b231.
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The modern plate tectonic paradigm provides a predictive model to understand what mediates dynamic processes at both plate margins and intraplate settings. At some locations on the Earth, the geological record provides evidence of apparent violations of this theoretical framework. In this dissertation, I examine a region on the rifted continental margin of Eastern North America, where at least four distinct episodes of magmatism occurred (in the Late Triassic, Early Jurassic, Early Cretaceous) since the onset of rifting and ultimate breakup of the supercontinent Pangea. It also coincides with a present-day low seismic velocity anomaly in the upper mantle. No other region on the Eastern North American Margin has a record of such anomalous dynamic processes occurring and persisting for more than 200 Myr. In this dissertation, I primarily use zircon U-Pb geochronology to establish the basic chronological framework in which magmatic and magmatic-hydrothermal systems in this region existed and persisted, establishing the temporal parameter space in which it will be possible to test geodynamic mechanisms for their formation.
In Chapter 2, I use ultra-high precision zircon U-Pb geochronology via Chemical Abrasion-Isotope Dilution-Thermal Ionization Mass Spectrometry (CA-ID-TIMS) to test whether the onset of magmatism in the largest igneous body in this region (the White Mountain Batholith) is linked to the eruption of the vast flood basalts within the Central Atlantic Magmatic Province (CAMP) and whether its apparent duration is indeed > 50 Myr, as previous workers using whole rock K-Ar and mineral Ar-Ar geochronologic methods suggest. My work uncovered a previously unknown episode of rift-related magmatism in the region that precedes the both the CAMP and the emplacement of the White Mountain Batholith by 3 – 5 Myr.
In Chapter 3, I use a combination of high-precision zircon U-Pb geochronology and absolute plate motion models to test whether the Cretaceous igneous province in this region resulted from hot spot magmatism as North America moved over the purported Great Meteor Hotspot. These results cannot falsify the hotspot hypothesis and the new zircon U-Pb ages therefore provide the best available chronological constraints for one of the longest-lived hot spot tracks on the Earth.
In Chapter 4, motivated by the confirmation of age discrepancies between low- and intermediate-temperature chronometers and the zircon U-Pb ages presented in Chapter 2, I use a combination of both CA-ID-TIMS and LA-ICP-MS zircon U-Pb geochronologic techniques to place constraints on the timing and duration of magmatism for the Late Triassic-Early Jurassic province. The results of this chapter demonstrate that the magmatism of the White Mountain Magma Series occurs in discrete pulses through much of the Jurassic. Together with zircon Hf isotopic analyses from select samples, I synthesize these age results and construct a hypothesis testing framework in which it will be possible for future investigators to unravel the geodynamic complexities in this region. I provide recommendations for future work and emphasize the need for unified approaches coupling geochronology, geochemistry, and geophysics, to test the range of possible mechanisms responsible for these episodes of anomalous tectono-magmatic activity.