Submitted by Simone Souza (simonecgsouza@hotmail.com) on 2017-11-09T15:52:59Z No. of bitstreams: 1 DISS_2014_Bruno Rodrigo Vasconcelos.pdf: 5036477 bytes, checksum: 20e651beee5cbd117234240287eef44f (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2018-02-02T15:29:02Z (GMT) No. of bitstreams: 1 DISS_2014_Bruno Rodrigo Vasconcelos.pdf: 5036477 bytes, checksum: 20e651beee5cbd117234240287eef44f (MD5) / Made available in DSpace on 2018-02-02T15:29:02Z (GMT). No. of bitstreams: 1 DISS_2014_Bruno Rodrigo Vasconcelos.pdf: 5036477 bytes, checksum: 20e651beee5cbd117234240287eef44f (MD5) Previous issue date: 2014-10-28 / Vários modelos deformacionais foram propostos para o Cinturão Paraguai diferindo principalmente quanto ao número de fases de deformação, sentido da vergência e estilo tectônico. Feições estruturais apresentadas neste trabalho indicam tectônica dominada por escamas de baixo ângulo de mergulho na fase inicial, seguida por duas fases deformacionais progressivas. A primeira fase de deformação (F1) é caracterizada por clivagem ardosiana (S1), com recristalização de minerais da fácies xisto verde, plano axial de dobras isoclinais recumbentes (D1) de direção NE associadas a zonas de falhamento reverso subhorizontais com movimentação de topo para SE. A segunda fase deformacional (F2) mostra vergência para NW, caracterizada por clivagem de crenulação (S2) plano axial de dobras abertas (D2) do acamamento e foliação S1, localmente associada a falhas reversas. A terceira fase de deformação é caracterizada por falhas e fraturas sub-verticais com direção NW mostrando movimentação sinistral, comumente preenchidas por veios de quartzo. O acervo de estruturas tectônicas e paragênese metamórfica descrita indicam que a deformação mais intensa, em nível crustal mais profundo, alcançou a fácies xisto verde durante F1. Acomodando expressivo encurtamento crustal por meio de dobras recumbente e zonas de cisalhamento de baixo ângulo com movimentação de topo para SE, em regime tectônico do tipo pelicular delgado. A fase F2 teve deformação menos intensa e se comportou de maneira rúptil-dúctil, acomodando discreto encurtamento por meio de dobras normais abertas e falhas inversas subverticais desenvolvidas em nível crustal mais raso, com vergência em direção ao Cráton Amazônico. A terceira fase deformacional (F3) foi menos intensa e acomodou encurtamento na forma de fraturas e falhas sinistrais subverticais, comumente preenchidas por veios de quartzo. / Several deformation models have been proposed for the Paraguay Belt, differing mainly in the number of deformation phases, sense of vergence and tectonic style. Structural features presented in this work indicate tectonic dominated by an initial phase of low dipping thrust sheets, followed by two progressive deformation phases. The first deformation phase (F1) is characterized by a slaty cleavage (S1), axial plane of isoclinal recumbent folds (D1) in the NE direction, with recrystallization of minerals from the greenschist facies, related to horizontal shear zones with top-to-the-SE sense of movement. The second stage shows a NW-vergence, characterized by crenulation cleavage, S0 and S1 axial planes of open folds, locally associated with reverse faults. The third deformation phase is characterized by subvertical faults and fractures in the NW direction showing sinistral movement, commonly filled by quartz veins. The collection of tectonic structures and metamorphic paragenesis described indicate that the most intense deformation, at deeper crustal level, reached the greenschist facies during F1. Accommodating significant crustal shortening through isoclinal recumbent folds and low-angle shear zones showing top-to-the SE sense of movement during a thin-skinned tectonic regime. The phase F2 showed more subtle deformation, with more competent rock types developing brittle behavior and less competent rock types developing ductile behavior, by accommodating slight shortening through normal open folds and subvertical reverse faults nucleated in shallower crustal level with vergence towards the Amazonian Craton. The third phase was less intense and shortening is accommodated in the form of fractures and subvertical sinistral faults, commonly filled by quartz veins.

No presente trabalho buscou-se compor um quadro geológico-estrutural da Faixa Paraguai meridional e compreender as relações estratigráficas entre os litotipos da Formação Puga e grupos Cuiabá e Corumbá. Foram realizados trabalhos de reconhecimento geológico e perfis geológico-estruturais de detalhe, com análise estrutural e petrográfica, em conjunto com a integração de dados e mapas existentes, análise de imagens de satélite, fotos aéreas e modelos digitais de terreno. A Faixa Paraguai meridional evoluiu como um típico fold-andthrust belt. A evolução geológica do cinturão principia por processos de rifteamento, provavelmente no final do Criogeniano, evoluindo para mar restrito e margem passiva até o final do Ediacarano. A fase rifte é caracterizada pelas formações Puga e Cerradinho. A fase margem passiva está representada pelas formações Bocaina, Tamengo e Guaicurus. Propõe-se que o Grupo Cuiabá na área estudada seja constituído por depósitos marinhos profundos, turbidíticos distais depositados comitantemente aos sedimentos do Grupo Corumbá. O processo colisional responsável pela inversão da bacia com a deformação e metamorfismo associados ocorreu durante o Cambriano, com magmatismo pós-colisional no Cambriano Superior. O estilo estrutural torna-se progressivamente mais complexo de oeste para leste. São observadas até três fases de dobramento coaxiais sobrepostas com eixos subhorizontais de direção N-S. Associam-se a sistemas de falhas de empurrão com deslocamento da capa para oeste. As lineações de estiramento e indicadores cinemáticos observados sugerem que a convergência colisional em direção ao bloco Rio Apa que deu origem à faixa móvel não foi completamente frontal, existindo algum grau de obliquidade, com vetores de convergência em torno de WNWENE. Os micaxistos do Grupo Cuiabá mostram o estilo estrutural mais complexo, com três fases de dobramentos coaxiais e foliações tectônicas mais intensas. Haveria correlação temporal entre S3 gerada nos micaxistos, comumente referidos como Grupo Cuiabá, a leste com a foliação S2 gerada na porção central e a clivagem S1 gerada no limite da área cratônica a oeste, padrão que pode ser explicado pela migração do front deformacional de leste para oeste. É sugestivo que as principais falhas de empurrão coincidam com limites bacinais importantes, onde ocorrem variações de espessura e representatividades das formações basais. No processo de inversão da bacia provavelmente os empurrões reativaram as antigas falhas lístricas principais do estágio rifte. / This work aims to characterize the geological and structural context of the Southern Paraguay Folded Belt, and to understand the stratigraphic relationships between the Puga Formation, Corumbá and Cuiabá groups. Regional geological reconnaissance work and detailed geological-structural field sections were carried out, with petrographic and structural analysis, together with integration of existing data and maps and analysis of satellite images, aerial photos and digital terrain models. The southern Paraguay Belt is a typical fold-andthrust belt. Its geological evolution began with rifting (Puga and Cerradinho formations), probably at the end of Criogenian, and evolved to restricted sea and passive margin (Bocaina, Tamengo and Guaicurus formations) in the late Ediacaran. It is proposed that the Cuiabá Group in the study area consists of distal marine deposits coeval with the Corumbá Group. The collisional process responsible for basin inversion and associated deformation and metamorphism occurred in the Cambrian, with post-collisional magmatism in the Upper Cambrian. The structural style becomes increasingly complex from west to east. Up to three overprinted coaxial folding phases are observed with north / south upright axial planes dipping to east and axes plunging gently to North or South. A system of thrust faults is associated with displacement of the hangwall to the west. Down-dip to oblique and strike-slip stretching lineations are also observed, with kinematic indicators showing movement varying from inverse to sinistral. This suggests that the collisional convergence toward the Rio Apa block which generated the mobile belt was not strictly frontal, but had some degree of obliquity, with convergence vectors around SSW - ENE. The Cuiabá Group mica-schists show the most complex structural style with three superimposed coaxial fold phases and more intense tectonic foliations. It is proposed that there would be time correlation between the S3 foliation in the mica-schists in the easternmost area, with the S2 foliation in the central area and the S1 cleavage at the limit of the cratonic area to the west. This pattern can be explained by the westward migration of the deformational front. It is suggestive that the main thrusts coincide with major basin boundaries, where greater variations in thickness and expression of the basal formations occur. During the basin inversion the thrusts probably reactivated the former main listric faults of the rift stage.

Alkalic porphyry style Au-Cu deposits of the Cadia district are associated with Late-Ordovician monzonite intrusions, which were emplaced during the final phase of Macquarie Arc magmatism at the end of the Benambran Orogeny. N-striking faults, including the curviplanar, northerly striking, moderately west-dipping basement thrust faults of the Cadiangullong system, developed early in the district history. NE-striking faults formed during rifting in the late Silurian. Subsequent E-W directed Siluro- Devonian extension followed by regional E-W shortening during the Devonian Tabberabberan Orogeny dismembered these intrusions, thereby superposing different levels porphyry Au-Cu systems as well as the host stratigraphy. During the late Silurian, the partially exhumed porphyry systems were buried beneath the Waugoola Group sedimentary cover sequence, which is generally preserved in the footwall of the Cadiangullong thrust fault system. The Waugoola Group is a typical rift-sag sequence, deposited initially in local fault-bounded basins which then transitioned to a gradually shallowing marine environment as local topography was overwhelmed. Basin geometry was controlled by pre-existing basement structures, which were subsequently inverted during the Devonian Tabberabberan Orogeny, offsetting the unconformity by up to 300m vertically. In the Waugoola Group cover, this shortening was accommodated via a complex network of minor detachments that strike parallel to major underlying basement faults. For this reason, faults and folds measured at the surface in the sedimentary cover can be used as a predictive tool to infer basement structures at depth. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Cette thèse traite de l’enregistrement de la déformation, à différentes échelles de temps et d’espace dans la chaîne plissée de Malargüe et le bloc de San Rafael, situés dans la partie septentrionale du bassin de Neuquén en Argentine. La première partie du travail comprend une analyse de la déformation finie (chaîne de Malargüe) et de la déformation active (bloc de San Rafael) à l’échelle macroscopique. De manière générale, les coupes structurales régionales proposées mettent clairement en évidence le rôle l’héritage structural lié aux structures générées lors de l’ouverture du bassin au Jurassique. Nous montrons également que les mécanismes de soulèvement actuels du bloc de San Rafael à l’est reprennent les modalités de la déformation d’âge Miocène dans la chaîne. Contrairement au mode de structuration des prismes critiques classiques caractérisés par la localisation de la déformation le long d’un niveau de décollement, la structuration de la chaîne est ici issue d’une déformation distribuée plus largement dans la lithosphère. A l’échelle de l’endommagement mesoscopique, la fracturation régionale nous a permis d’enregistrer les différents champs de contraintes régionaux liés aux phases de raccourcissement depuis le domaine pré-plissement jusqu’à la phase syn-plissement. Ces différentes phases sont en accord avec la cinématique de la convergence de la plaque Nazca depuis le Crétacé supérieur. A l’échelle microscopique, l’analyse des propriétés de susceptibilité magnétique des roches met en évidence, d’une part, une compartimentalisation de la déformation à l’échelle de la matrice liée à l’héritage structural extensif. D’autre part, la distribution spatiale de cet endommagement ne démontre pas l’existence de gradient clair des fabriques magnétiques depuis l’avant-pays vers les zones internes ce qui confirme le caractère atypique du système Andin à la latitude de 35°S. Ce dernier étant principalement contrôlé par une déformation distribuée, liée à l’héritage structural et singulièrement différente de celle attendu dans le cadre de la théorie du prisme critique. / This PhD project deals with multiscale record of the tectonic signal in the Malargüe fold-and-thrust-belt (MFTB) located in the northern part of the Neuquén basin (Argentina). The first results presented rely on the study of the macroscopic finite strain in the fold-belt and the characterization of the active deformation of the San Rafael Block uplift. The cross-sections we produce show that structural inheritance related to the Jurassic extension is the main parameter controlling the belt structure. In addition we proposed that the building mechanisms that controlled the MFTB evolution by Miocene times are the same than those triggering the present day San Rafael block uplift. The second part of this work is dedicated to mesoscopic strain pattern analysis recorded by fracture networks. Throughout the MFTB, we are able to describe the occurrence of four main fractures sets emplaced in several stress regime that are linked (1) to the inheritance and (2) to the well-known compression phases from pre-folding to syn-folding settings. Finally the third part of this work describes the microscopic damage recorded by the anisotropy of magnetic susceptibility method. We mainly evidence that there is no clear gradient of magnetic fabrics from foreland to hinterland and that deformation is compartmentalized by structural inheritance. This atypical pattern of magnetic fabrics succession reveals that the matrix damage is governed by the same strain distribution as those observed at macroscopic scale thus providing a supplementary argument to consider the Andean system at these latitudes as singularly different from a classical Coulomb wedge.

La péninsule de la Gaspésie (Québec, Canada) présente un potentiel pétrolier dans les roches datées de l'Ordovicien tardif au Dévonien inférieur. Dans l'est de la ceinture de Gaspé, des puits producteurs de gaz prouvent la présence de réservoirs pétroliers. Des nouvelles études structurales et des études de bassin dans la ceinture de Gaspé permettent de mieux évaluer le potentiel pétrolier de cette région. Nous présentons ici une nouvelle méthodologie pour la prospection d'hydrocarbures dans les régions de piémont de type « fold and thrust belt » comme la ceinture de Gaspé. Nous avons développé cette méthodologie en la testant au niveau de la partie centrale de la ceinture de Gaspé. Nous avons intégré les données géologiques et géophysiques disponibles pour l'étape d'imagerie sismique 2D afin de construire une image sismique directement en profondeur, ce qui a permis d'améliorer l'interprétation structurale, notamment la caractérisation des structures profondes et des failles majeures. Ce travail est suivi d'une modélisation de bassin afin d'évaluer le potentiel pétrolier. Cette étude s'effectue en plusieurs étapes : 1) La construction du modèle structural : L'intégration des données géologiques dans l'étape de la migration en profondeur avant sommation permet d'améliorer le rendu des images sismiques. Ces nouvelles images sont plus fiables et, étant migrées directement en profondeur, rendent les interprétations plus proches de la géometrie réelle du sous-sol. Ces informations permettent de construire un modèle géologique plus complexe et de mieux contraindre le modèle structural de la ceinture acadienne. Les nouvelles interprétations ont permis en particulier, de mieux comprendre la relation entre les ceintures acadienne et taconienne. 2) L'évolution du modèle structural : il a été possible de valider la cohérence de la géométrie structurale grâce aux techniques de restauration. Cependant ce procédé n'a été appliqué qu'au niveau du Synclinal du Lac des Huit-Miles sur les successions stratigraphiques siluro-dévoniennes de la ceinture acadienne : les formations cambroordoviciennes ont été déformées par les orogenèses taconiennes et acadiennes ce qui rend impossible leur restauration. Ce scénario cinématique a été utilisé pour comprendre l'évolution géodynamique de la ceinture de Gaspé et ainsi permettre de proposer une nouvelle géométrie plus favorable à la production et à la migration des hydrocarbures. 3) Évaluation du système pétrolier : Suite à l'étape de restauration, la modélisation de bassin avec le logiciel Temis2D® a été appliquée à la succession stratigraphique Silurien-Dévonien du synclinal du Lac des Huit-Milles et à l'anticlinal de Causapscal. Temis2D® a permis de prédire l'évolution de la roche mère et le degré de maturation ainsi que la génération et l'expulsion des hydrocarbures, en utilisant le modèle structural et les données géochimiques des puits de la ceinture de Gaspé.

Enhancement methods applied on various satellite images (ASTER, ETM and RADAR SAT-1) facilitated the identification and mapping of tectonic fractures in the Zagros fold-and-thrust belt in southwest Iran. The results of the fracture analysis on these enhanced images reveal four principal fracture sets within each fold structure: (i) an axial set defined by normal faults oriented parallel to the fold axial trace, (ii) a cross-axial, extensional fracture set oriented perpendicular to the fold axial trace, (iii) and two sets of intersecting shear fractures, oriented at an acute angle to the cross-axial set. Study of the enhanced images also revealed five fracture sets along the Kazerun fault zone: (i) Riedel R- and R'-shear fracture sets, (ii) extensional T fracture set oriented at a high angle to the trace of the main Kazerun fault, (iii) oblique, synthetic P-shear fracture set, at a low angle to the trace of the main Kazerun fault, and (iv) synthetic Y-shear displacement fracture set, oriented sub-parallel to the main trace of the fault. The estimated mean azimuths of the shortening that developed the fold- and fault-related fracture systems are remarkably close, and are oriented perpendicular to the general NW-SE trend of the Zagros fold-and-thrust belt. The sampling and analysis of the fold- and fault-related fracture systems were done in a GIS environment. This study shows that an analysis of enhanced satellite images can reveal significant information on the deformation style, timing, and kinematics of the Zagros fold-and-thrust belt. This study suggests that the Zagros orogenic belt, which has mainly been forming since Miocene, due to the convergence of the Iranian and Arabian subplates, has evolved both by thin- and thick-skinned tectonics. Reconfiguration of the Precambrian basement blocks, and the ensuing slip and rotation along the Precambrian faults during the Zagros orogeny, have deformed the folds, and redistributed the fold-related fractures through rigid-body rotation.

The Late Cretaceous Trail Member of the Ericson Sandstone represents a regionally extensive fluvial system that transported sediments from the Sevier fold and thrust belt and Uinta Mountain uplift to the Western Interior Seaway. The Trail Member is a petroleum reservoir target that has unpredictable production rates due to the unknown behavior and connectivity of channel sandstones. The abundant outcrop, wellbore, and core data available allows for a comprehensive analysis of how the fluvial architecture, connectivity, and reservoir quality change along 65 km of depositional dip. Observations made at Flaming Gorge and Clay Basin (most landward field locations) suggest a highly mobile fluvial system that was influenced by both autogenic channel clustering and allogenic forcing. Evidence is seen for movement along the Sevier fold and thrust belt and early Laramide uplift of the Uinta Mountains. Specifically, three zones identify temporal tectonic changes throughout deposition of the Trail Member. The Upper and Lower Trail zones represent times of low accommodation as the fluvial system must avulse and move laterally to find available space. The Middle Trail zone represents a higher accommodation setting with internal autogenic channel clustering. This shows that on a finer timescale, autogenic processes control sediment distribution, while on a longer timescale, external drivers, specifically tectonics, control the distribution of sediment in the Trail fluvial system. Significant changes were observed within the Trail Member towards the basin. At Northern Colorado, lenticular, fluvial-dominated sands are still common, preserved organic and woody material, mud cracks, and increased bioturbation are observed that are not present elsewhere. The sandstone channels are slightly wider, have more common occurrences of low flow-regime sedimentary structures such as ripples and mud cracks, and appear to be more individually isolated with thin fine-grained material surrounding the channels. On a larger scale, photogrammetric analysis shows a rapid lateral change (0.3 km) from a sand-rich, channel-dominated expression to a mud-rich, channel-poor character. These observations suggest a lower energy fluvial system focused within a possible incised valley showing that the fluvial system is being influenced primarily by eustatic forces, rather than tectonics. Subsurface data from twelve wells located north of the Northern Colorado locality show a rapid (15 km) increase in thickness (97 m to 182 m) and decrease in net-to-gross (89.3% to 65.3%). Early subsidence of the Washakie sub-basin just east of the wells could account for the rapid increase in accommodation. Another possible explanation for the rapid thickness increase to the northeast could be the presence of an incised valley. These possibilities show the complexity of the environment within which the Trail Member fluvial system deposited sediments.

Des modèles géométriques ont été proposés pour reconstruire la géométrie de plis associés aux rampes (par exemple pli sur flexure de faille), en identifiant en particulier la profondeur de niveau de décollement et le déplacement total sur la rampe. Ces méthodes de reconstruction géométrique sont appliquées pour des plis partiellement érodés. Au cours de l'érosion, le cut-off de la rampe peut être érodé et, par conséquent, le déplacement sur la rampe est difficile à quantifier. Dans cette thèse, nous développons onze modèles thermo-géométriques. Les modèles combinent les données géométriques et les données d’enfouissement pour proposer une évolution cinématique d’un pli avec cut-off érodé. Nous supposons que la mise en place d'une unité tectonique produit une anomalie thermique dans le mur de la faille, et que cette anomalie thermique pourrait indiquer une épaisseur de bloc chevauchant. Les modèles fournissent une estimation de la profondeur de décollement et le déplacement total sur une rampe érodée, qui ne dépend pas de taux d’érosion. Dans le cas de chevauchements actifs, les modèles proposent un taux de déplacement et un âge de l'initiation de la faille en fonction de taux d'érosion. Ces données sont utilisées pour proposer un développement cinématique de coupes érodées. Nous appliquons les modèles sur les plis érodés et actif à Taiwan dans les zones de Choshui et Miaoli. On propose des coupes régionales équilibrées en utilisant la technique de modélisation directe. Dans la section Choshui, nous proposons un niveau de détachement de ~5 km à ~14 km, marquée par deux sauts successifs de rampes de ~5 km and ~4 km. En supposant un taux d'érosion à 4 mm/an, l'âge de l’initiation de chevauchement active est entre 3,3 Ma dans la partie intérieure de prisme (Chevauchement de Tili) à 0,9 Ma dans la partie extérieur (Chevauchement de Chelungpu). Le raccourcissement totale sur la coupe de Choshui est ~100 km et le taux de déplacement calculé est ~1 cm/an. Pour tester nos modèles thermo-géométriques dans une chaîne plissée inactive, on applique nos modèles sur les plis érodés associés aux failles de Pine Mountain et Jones Valley dans la chaîne plissée des Appalaches. L'application des modèles thermo-géométriques nous permet d’estimer une quantité de déplacement sur les deux failles et expliquer de manière satisfaisante l'anomalie thermique dans le mur des failles de Pine Mountain et Jones Valley. Afin d'améliorer la description de l’anomalie thermique qui se développe dans le soubassement des failles, on a étudié l'évolution des minéraux magnétiques des roches argileuses le long de quatre sections dans la chaîne plissée à Taiwan. On a remarqué que la greigite (Fe3S4) domine l'assemblage magnétique dans les roches enfouies à moins à moins de de 70°C. La magnétite (Fe3O4) se développe pour des températures d’enfouissement de ~50°C et domine l’assemblage magnétique jusqu'à ~350° C. A partir ~300°C, la pyrrhotite monoclinique (Fe7S8) se développe aux dépens de la magnétite, et à ~350°C, la magnétite n'est plus détecté. Ces résultats peuvent être utilisés en complément d'autres géothermomètres pour identifier les anomalies thermiques dans une gamme de de 50-70°C et de 300-350°C où les caractéristiques des minéraux magnétiques sont identifiées / Geometric models have been proposed to account satisfactorily for ramp-related folds (e.g. fault-bend fold), identifying in particular detachment depth and total shortening. These methods of geometric reconstruction are applied on partially eroded folds. During erosion, the fault cut-off may be removed and as a result, the displacement is difficult to quantify. In this thesis, we develop 11 thermo-geometric models combining geometric description of folds and burial data to propose kinematic evolution of folds with eroded cut-offs. We assume that the emplacement of a tectonic unit will result in a thermal anomaly in the footwall, and that this thermal anomaly might indicate a thickness of the overriding unit. The models provide an estimation of the detachment depth and the total shortening on an eroded ramp, independent of the erosion rate. In the case of active thrusts, the models provide an estimation of the slip rate and the age of the initiation of the thrust as a function of the erosion rate. These data are used to unravel the kinematic development of eroded cross-sections. We apply the models on eroded folds from Taiwan underlined by active thrusts in the Choshui and Miaoli sections. We propose regional balanced cross-sections using forward modeling technique. In the Choshui section, we propose a detachment profile with a depth between ~ 5 km and ~ 14 km, marked by two steps of ~ 5 km. Assuming erosion rate at 4 mm/a, the age of initiation of the active thrusts is ranging from 3.3 Ma inward (Tili thrust) to 0.9 Ma outward (Chelungpu thrust). The total shortening from the whole section is ~100 km and the calculated slip rate is about 1 cm/a. To test our models in a non-active fold-and-thrust belt, we study eroded folds associated to the Pine Mountain thrust and Jones Valley thrust from the Appalachian belt. The application of the thermo-geometric models provides a value of the total shortening and explains satisfactorily the thermal anomaly in the footwall of the Jones Valley thrust. In order to improve the description of the thermal anomaly, we have studied the evolution of magnetic minerals of argillaceous rocks in four sections from the Taiwan thrust belt. We found that the iron sulfide greigite (Fe3S4) is dominating the magnetic assemblage in the less buried rocks (<70°C). The magnetite (Fe3O4) develops at burial temperature of ~50°C and is dominating the magnetic assemblage up to ~350°C. By ~300°C, the monoclinic pyrrhotite (Fe7S8) develops at the expense of magnetite, and at ~350°C, the magnetite is no longer detected. These results can be used complementary to other geothermometers to identify thermal anomalies in the range 50-70°C and 300-350°C where characteristic magnetic minerals are identified

L’Anatolie fait partie d’un vaste domaine orogénique qui s’étend des Alpes à l’Himalaya. Les sutures ophiolitiques rencontrées marquent les cicatrices de plusieurs domaines océaniques (branches de la Néotéthys Nord), interdigités entre plusieurs blocs crustaux au cours du Mésozoïque. La fermeture de ces domaines au Crétacé supérieur est accompagnée de la mise en place de bassins tertiaires syn-orogéniques dont fait partie le Bassin de Sivas, limité au nord par le bloc du Kırşehir et au Sud par les Taurides. Une étude structurale de terrain, complétée d’analyses géochimiques, biostratigraphiques et thermochronologiques ainsi que l’étude de 700 km de lignes sismiques 2D inédites, a été menée pour tenter de comprendre (i) le contexte géodynamique régional et (ii) l’architecture tectono-sédimentaire de ce bassin.L’étude des ophiolites présentes le long de la bordure sud du Bassin de Sivas met en évidence des péridotites intensément serpentinisées. La partie supérieure de l’ophiolite présente des brèches et ophicalcites caractéristiques de l’exhumation mantellique, alors que l’analyse géochimique des corps magmatiques révèle un environnement de supra-subduction, daté à circa 90 Ma (U-Pb sur zircon). Ces analyses démontrent la présence d’un domaine océanique embryonnaire entre le Kırşehir et les Taurides, dont la fermeture s’initie le long d’ancienne failles de détachement. L’obduction de la nappe de péridotite et de son mélange frontal sur la marge Nord des Taurides entre le Turonien et le Maastrichtien, permet de former le « socle ophiolitique » commun aux bassins est-anatoliens. L’analyse détaillée de la partie centrale du bassin, en carte et à l’aide de lignes sismiques 2D inédites et de thermochronologie basse température [AFTA et (U-Th)/sur apatite], a permis de proposer un modèle d’évolution cinématique sur la base de coupes équilibrées. La propagation de la déformation vers le Nord, initiée dès l’Eocène inférieur, permet l’isolation progressive du bassin et une forte accumulation d’évaporites à l’Eocène supérieur. Les dépôts de l’Oligo-miocène sont ensuite contrôlés par l’halocinèse, permettant la mise en place de deux générations de mini-bassins salifère, séparés d’une canopée. Les géométries dans le domaine halocinétique, et les variations latérales dans le bassin, montrent le contrôle exercé par (i) le bassin pré-évaporite affleurant le long de la moitié sud du bassin et (ii) l’épaisseur du niveau de sel initial.L’intégration de ces observations à l’échelle régionale met en évidence un contrôle du raccourcissement crustal, dans les Taurides et les bassins tertiaires, lié à la fermeture de la Néotéthys Sud, en générant l’émergence de structures de socles. La collision enregistrée à l’Oligocène supérieur - Miocène lors de l’indentation de la plaque Arabe le long des Taurides est contemporaine de la déformation du Bassin de Sivas et des bassins adjacents. / Anatolia is part of a vast orogenic domain that extends from the Alps to the Himalayas. Numerous ophiolitic sutures defined the remnants of several oceanic domains (Northern and southern Neotethys), between continental fragments formed during Mesozoic time. Oceanic closure during Late Cretaceous is recorded by the establishment of syn-orogenic tertiary basins, including the Sivas Basin bounded to the north by the Kırşehir block and to the south by the Taurides. An extended study based on field and completed by geochemistry, biostratigraphy and thermochronology analyzes and more than 700 km unpublished seismic data, was conducted to resolve (i) the regional geodynamic context and (ii) the tectono-sedimentary architecture of this basin.The ophiolites located along the southern edge of the Sivas Basin are made of serpentinized peridotites. The upper part of the ophiolite present breccias and ophicalcites commonly described as associated to mantle exhumation environment, while the geochemical analysis of the magmatic bodies reveals a supra-subduction environment dated at circa 90 Ma (U-Pb on zircon). These observations are in agreement with an embryonic ocean domain located between the Kırşehir and the Taurides, the closure which was initiated along fossil detachment faults. The obduction of the peridotite nappe and its frontal mélange on the northern margin of the Taurides between the Turonian and the Maastrichtian allows forming the “ophiolitic basement” of the east-anatolian basins.A detailed map and cross-section analysis, supported by 2D seismic lines and low-temperature thermochronology [AFTA and (U-Th) / on apatite], resulted in a kinematic evolution model and the realization of balanced cross-sections. The propagation of the deformation towards the north, initiated in the Lower Eocene, results in the progressive isolation of the basin and a strong accumulation of evaporites during the Upper Eocene. The Oligo-Miocene depocenters were controlled by halokinesis, forming two generations of mini-basins, separated by a salt canopy. The geometries in the halokinetic domain and the lateral variations in the basin show the control exerted by (i) the pre-evaporite basin outcropping along the southern half of the basin and (ii) the thickness of the initial salt level.Integration at the regional scale within the Taurides highlights the propagation of crustal shortening related to the Southern Neotethys closure, which formed linear tectonic basement exhumation. The collision recorded in the Upper Oligocene - Miocene during the indentation of the Arabic plate along the Taurides is contemporaneous to the deformation the Sivas Basin.