15 research outputs found
Déformation active, cinématique et mécanique de l'Est de la Sicile : Analyse morphostructurale et modélisation analogique
In Central Mediterranean, Sicily is known for its intense volcanic activity (Mount Etna, Aeolian Islands) and its major historical earthquakes (Noto, 1693, M 7.4 ; Messina, 1908, M 7.1). These events reflect a particularly active geodynamic context, controlled by deformation mechanisms and interactions between deep tectonics and surface processes (erosion, sedimentation) that are still poorly understood.During the Mesozoic, the opening of the Neo-Tethys, between the future Europe and Africa plates, shaped the geometry of the surrounding continental margins, particularly in the North African domain. The Alpine Tethys, the western branch of this ancient ocean, closed during the Cenozoic through a system of fast subductions and collisions developing in a context of slow convergence between the Africa and Eurasia plates. The Calabro-Sicilian Arc, and more generally the Apennines-Maghreb system, result from the retreat of the Alpine Tethys, followed by the continental subduction of the African and Apulian margins under the AlKaPeCa continental blocks (Alboran, Kabylia, Peloritan and Calabria) with the African and Apulian margins. These micro-continental blocks, derived from the European margin, accompanied the slab rollback towards the South-East, localizing at their front the accretion of the Alpine Tethys sedimentary cover and opening in their wakes a series of back-arc basins (Algerian-Provençal and Tyrrhenian basins). From North to South, Eastern Sicily is divided into four tectono-stratigraphic domains : 1) the Peloritain-Calabria block, detached from the Corso-Sardinian micro-continent since the opening of the Tyrrhenian 15 Ma ago, 2) the pelagic sediments of the Alpine Tethys, remnants of the oceanic accretionary prism, 3) the Meso-Cenozoic cover of the African margin accreted since the Middle Miocene, and 4) the present day foreland represented by a thick carbonate platform (Hyblean Plateau), separated from the Ionian domain by the Malta Escarpment.This thesis focuses on the crustal deformation processes and their interactions with deep dynamics based on the analysis of geological, geophysical and morpho-structural data, coupled with analytical and analogue modeling. My work first led to a new interpretation of the origin of the Hyblean Plateau (SE of Sicily). This sub-circular topographic anomaly, 1000 m high and 80 km in diameter, is inherited from an uplift phase that started in the Late Miocene, simultaneously with major magmatic episodes in this region. Unlike the commonly evoked flexural model, most of the uplift is probably related to magmatic intrusions deforming the thick Meso-Cenozoic carbonate cover. Analogue models mechanically validated the hypothesis of a tectono-magmatic scenario at the origin of the present day morphology and outlined the major effect of structural inheritance in the localization of the subsurface deformation. Based on a critical review of the available geological data, I also proposed a new tectono-stratigraphic reconstruction of the Sicilian Fold-and-Thrust Belt. Once again, analogue modeling provided strong constraints on the African margin paleogeography and mechano-stratigraphy, as well as the dynamics of the deformation and the tectonic-erosion-sedimentation interactions involved in the building of the Sicilian orogenic prism. Finally, I studied the transition zone between the Sicilian Belt and the Calabrian Prism, in its four dimensions, in order to specify the current kinematics of this potentially highly seismogenic region. Based on bathymetric and seismic data, the mechanisms of the deformation at the origin of the onshore and offshore fault networks are explained by the dynamics imposed by the lower plate and those resulting from the migration of the Calabrian Arc and the oceanic accretionary prism towards the Southeast.SituĂ©e au cĆur de la MĂ©diterranĂ©e, la Sicile est connue pour son activitĂ© volcanique intense (Mont Etna, Ăźles Eoliennes) et ses sĂ©ismes historiques majeurs (Noto, 1693, M 7.4; Messine, 1908, M 7.1). Ces Ă©vĂ©nements traduisent un contexte gĂ©odynamique particuliĂšrement actif, contrĂŽlĂ© par des mĂ©canismes de dĂ©formation et des interactions entre la tectonique profonde et les processus de surface (Ă©rosion, sĂ©dimentation) encore mal connus.Au cours du MĂ©sozoĂŻque, lâouverture de la NĂ©o-TĂ©thys, entre les futures plaques Europe et Afrique, a modelĂ©e la gĂ©omĂ©trie des marges continentales, notamment dans le domaine Nord Africain. La TĂ©thys Alpine, branche occidentale de cet ancien ocĂ©an, sâest refermĂ©e durant le CĂ©nozoĂŻque via un systĂšme de subductions et de collisions rapides se dĂ©veloppant dans un contexte de convergence lente entre les plaques Afrique et Eurasie. LâArc Calabro-Sicilien, et plus gĂ©nĂ©ralement le systĂšme Apennins-MaghrĂ©bides, rĂ©sultent du retrait de la subduction de la TĂ©thys Alpine, puis de la subduction continentale des marges Africaine et Apulienne sous les blocs continentaux AlKaPeCa (Alboran, Kabylie, Peloritain et Calabre). Ces micro-bloc dĂ©rivĂ©s de la marge EuropĂ©enne ont accompagnĂ© le retrait de la subduction vers le Sud-Est, localisant Ă leur front lâaccrĂ©tion de la couverture sĂ©dimentaire de la TĂ©thys et ouvrant dans leur sillage une sĂ©rie de bassins arriĂšre-arc (bassins AlgĂ©ro-Provençal et TyrrhĂ©nien). Du Nord au Sud, la Sicile orientale est divisĂ©e en quatre domaines tectono-stratigraphiques : 1) le bloc Peloritain-Calabre, dĂ©tachĂ© du micro-continent Corso-Sarde depuis lâouverture de la Mer TyrrhĂ©nienne il y a 15 Ma, 2) les sĂ©diments pĂ©lagiques tĂ©thysiens, vestiges du prisme dâaccrĂ©tion ocĂ©anique, 3) la couverture MĂ©so-CĂ©nozoĂŻque de la marge Africaine accrĂ©tĂ©e depuis le MiocĂšne Moyen, et 4) lâavant-pays actuel reprĂ©sentĂ© par une Ă©paisse plateforme carbonatĂ©e (Plateau HyblĂ©en), sĂ©parĂ©e du domaine Ionien par lâEscarpement de Malte.Cette thĂšse sâintĂ©resse aux processus de la dĂ©formation crustale et leurs interactions avec la dynamique profonde Ă partir de lâanalyse de donnĂ©es gĂ©ologiques, gĂ©ophysiques et morpho-structurales, couplĂ©e Ă des modĂ©lisations analytiques et analogiques. Mes travaux ont dâabord conduit Ă une nouvelle interprĂ©tation de lâorigine du Plateau HyblĂ©en (SE de la Sicile). Cette anomalie topographique sub-circulaire de 1000 m dâaltitude et de 80 km de diamĂštre est hĂ©ritĂ©e dâun soulĂšvement qui a dĂ©butĂ© Ă la fin du MiocĂšne, contemporain dâĂ©pisodes magmatiques majeurs dans cette rĂ©gion. Contrairement au modĂšle flexural couramment Ă©voquĂ©, la majeure partie du soulĂšvement est probablement liĂ©e Ă des intrusions magmatiques dĂ©formant lâĂ©paisse couverture MĂ©so-CĂ©nozoĂŻque carbonatĂ©e. Des modĂšles analogiques ont permis de valider mĂ©caniquement lâhypothĂšse dâun scĂ©nario tectono-magmatique Ă lâorigine de la morphologie du Plateau HyblĂ©en, et de souligner le rĂŽle majeur de lâhĂ©ritage structural dans la localisation de la dĂ©formation en subsurface. A partir dâune revue critique des donnĂ©es gĂ©ologiques disponibles, jâai Ă©galement proposĂ© une nouvelle reconstruction tectono-stratigraphique de la ChaĂźne Sicilienne. Ici encore, la modĂ©lisation analogique a apportĂ© des contraintes fortes sur la palĂ©ogĂ©ographie et la mĂ©cano-stratigraphie de la marge Africaine, ainsi que sur la dynamique de la dĂ©formation et les interactions tectonique-Ă©rosion-sĂ©dimentation associĂ©es Ă la construction du prisme orogĂ©nique. Enfin, jâai Ă©tudiĂ©e la zone de transition entre la ChaĂźne Sicilienne et le Prisme Calabrais dans ses quatre dimensions, afin de prĂ©ciser la cinĂ©matique actuelle de cette rĂ©gion Ă fort potentiel sismique. Sur la base de donnĂ©es bathymĂ©triques et sismiques, les mĂ©canismes de la dĂ©formation Ă lâorigine des rĂ©seaux de failles Ă terre et en mer sont expliquĂ©s par la dynamique imposĂ©e par la plaque infĂ©rieure et celle issue de la migration de lâArc Calabrais et du prisme dâaccrĂ©tion vers le Sud-Est
Active deformation, kinematics and mechanics of Eastern Sicily : morphostructurale analysis and analogue modeling
SituĂ©e au cĆur de la MĂ©diterranĂ©e, la Sicile est connue pour son activitĂ© volcanique intense (Mont Etna, Ăźles Eoliennes) et ses sĂ©ismes historiques majeurs (Noto, 1693, M 7.4; Messine, 1908, M 7.1). Ces Ă©vĂ©nements traduisent un contexte gĂ©odynamique particuliĂšrement actif, contrĂŽlĂ© par des mĂ©canismes de dĂ©formation et des interactions entre la tectonique profonde et les processus de surface (Ă©rosion, sĂ©dimentation) encore mal connus.Au cours du MĂ©sozoĂŻque, lâouverture de la NĂ©o-TĂ©thys, entre les futures plaques Europe et Afrique, a modelĂ©e la gĂ©omĂ©trie des marges continentales, notamment dans le domaine Nord Africain. La TĂ©thys Alpine, branche occidentale de cet ancien ocĂ©an, sâest refermĂ©e durant le CĂ©nozoĂŻque via un systĂšme de subductions et de collisions rapides se dĂ©veloppant dans un contexte de convergence lente entre les plaques Afrique et Eurasie. LâArc Calabro-Sicilien, et plus gĂ©nĂ©ralement le systĂšme Apennins-MaghrĂ©bides, rĂ©sultent du retrait de la subduction de la TĂ©thys Alpine, puis de la subduction continentale des marges Africaine et Apulienne sous les blocs continentaux AlKaPeCa (Alboran, Kabylie, Peloritain et Calabre). Ces micro-bloc dĂ©rivĂ©s de la marge EuropĂ©enne ont accompagnĂ© le retrait de la subduction vers le Sud-Est, localisant Ă leur front lâaccrĂ©tion de la couverture sĂ©dimentaire de la TĂ©thys et ouvrant dans leur sillage une sĂ©rie de bassins arriĂšre-arc (bassins AlgĂ©ro-Provençal et TyrrhĂ©nien). Du Nord au Sud, la Sicile orientale est divisĂ©e en quatre domaines tectono-stratigraphiques : 1) le bloc Peloritain-Calabre, dĂ©tachĂ© du micro-continent Corso-Sarde depuis lâouverture de la Mer TyrrhĂ©nienne il y a 15 Ma, 2) les sĂ©diments pĂ©lagiques tĂ©thysiens, vestiges du prisme dâaccrĂ©tion ocĂ©anique, 3) la couverture MĂ©so-CĂ©nozoĂŻque de la marge Africaine accrĂ©tĂ©e depuis le MiocĂšne Moyen, et 4) lâavant-pays actuel reprĂ©sentĂ© par une Ă©paisse plateforme carbonatĂ©e (Plateau HyblĂ©en), sĂ©parĂ©e du domaine Ionien par lâEscarpement de Malte.Cette thĂšse sâintĂ©resse aux processus de la dĂ©formation crustale et leurs interactions avec la dynamique profonde Ă partir de lâanalyse de donnĂ©es gĂ©ologiques, gĂ©ophysiques et morpho-structurales, couplĂ©e Ă des modĂ©lisations analytiques et analogiques. Mes travaux ont dâabord conduit Ă une nouvelle interprĂ©tation de lâorigine du Plateau HyblĂ©en (SE de la Sicile). Cette anomalie topographique sub-circulaire de 1000 m dâaltitude et de 80 km de diamĂštre est hĂ©ritĂ©e dâun soulĂšvement qui a dĂ©butĂ© Ă la fin du MiocĂšne, contemporain dâĂ©pisodes magmatiques majeurs dans cette rĂ©gion. Contrairement au modĂšle flexural couramment Ă©voquĂ©, la majeure partie du soulĂšvement est probablement liĂ©e Ă des intrusions magmatiques dĂ©formant lâĂ©paisse couverture MĂ©so-CĂ©nozoĂŻque carbonatĂ©e. Des modĂšles analogiques ont permis de valider mĂ©caniquement lâhypothĂšse dâun scĂ©nario tectono-magmatique Ă lâorigine de la morphologie du Plateau HyblĂ©en, et de souligner le rĂŽle majeur de lâhĂ©ritage structural dans la localisation de la dĂ©formation en subsurface. A partir dâune revue critique des donnĂ©es gĂ©ologiques disponibles, jâai Ă©galement proposĂ© une nouvelle reconstruction tectono-stratigraphique de la ChaĂźne Sicilienne. Ici encore, la modĂ©lisation analogique a apportĂ© des contraintes fortes sur la palĂ©ogĂ©ographie et la mĂ©cano-stratigraphie de la marge Africaine, ainsi que sur la dynamique de la dĂ©formation et les interactions tectonique-Ă©rosion-sĂ©dimentation associĂ©es Ă la construction du prisme orogĂ©nique. Enfin, jâai Ă©tudiĂ©e la zone de transition entre la ChaĂźne Sicilienne et le Prisme Calabrais dans ses quatre dimensions, afin de prĂ©ciser la cinĂ©matique actuelle de cette rĂ©gion Ă fort potentiel sismique. Sur la base de donnĂ©es bathymĂ©triques et sismiques, les mĂ©canismes de la dĂ©formation Ă lâorigine des rĂ©seaux de failles Ă terre et en mer sont expliquĂ©s par la dynamique imposĂ©e par la plaque infĂ©rieure et celle issue de la migration de lâArc Calabrais et du prisme dâaccrĂ©tion vers le Sud-Est.In Central Mediterranean, Sicily is known for its intense volcanic activity (Mount Etna, Aeolian Islands) and its major historical earthquakes (Noto, 1693, M 7.4 ; Messina, 1908, M 7.1). These events reflect a particularly active geodynamic context, controlled by deformation mechanisms and interactions between deep tectonics and surface processes (erosion, sedimentation) that are still poorly understood.During the Mesozoic, the opening of the Neo-Tethys, between the future Europe and Africa plates, shaped the geometry of the surrounding continental margins, particularly in the North African domain. The Alpine Tethys, the western branch of this ancient ocean, closed during the Cenozoic through a system of fast subductions and collisions developing in a context of slow convergence between the Africa and Eurasia plates. The Calabro-Sicilian Arc, and more generally the Apennines-Maghreb system, result from the retreat of the Alpine Tethys, followed by the continental subduction of the African and Apulian margins under the AlKaPeCa continental blocks (Alboran, Kabylia, Peloritan and Calabria) with the African and Apulian margins. These micro-continental blocks, derived from the European margin, accompanied the slab rollback towards the South-East, localizing at their front the accretion of the Alpine Tethys sedimentary cover and opening in their wakes a series of back-arc basins (Algerian-Provençal and Tyrrhenian basins). From North to South, Eastern Sicily is divided into four tectono-stratigraphic domains : 1) the Peloritain-Calabria block, detached from the Corso-Sardinian micro-continent since the opening of the Tyrrhenian 15 Ma ago, 2) the pelagic sediments of the Alpine Tethys, remnants of the oceanic accretionary prism, 3) the Meso-Cenozoic cover of the African margin accreted since the Middle Miocene, and 4) the present day foreland represented by a thick carbonate platform (Hyblean Plateau), separated from the Ionian domain by the Malta Escarpment.This thesis focuses on the crustal deformation processes and their interactions with deep dynamics based on the analysis of geological, geophysical and morpho-structural data, coupled with analytical and analogue modeling. My work first led to a new interpretation of the origin of the Hyblean Plateau (SE of Sicily). This sub-circular topographic anomaly, 1000 m high and 80 km in diameter, is inherited from an uplift phase that started in the Late Miocene, simultaneously with major magmatic episodes in this region. Unlike the commonly evoked flexural model, most of the uplift is probably related to magmatic intrusions deforming the thick Meso-Cenozoic carbonate cover. Analogue models mechanically validated the hypothesis of a tectono-magmatic scenario at the origin of the present day morphology and outlined the major effect of structural inheritance in the localization of the subsurface deformation. Based on a critical review of the available geological data, I also proposed a new tectono-stratigraphic reconstruction of the Sicilian Fold-and-Thrust Belt. Once again, analogue modeling provided strong constraints on the African margin paleogeography and mechano-stratigraphy, as well as the dynamics of the deformation and the tectonic-erosion-sedimentation interactions involved in the building of the Sicilian orogenic prism. Finally, I studied the transition zone between the Sicilian Belt and the Calabrian Prism, in its four dimensions, in order to specify the current kinematics of this potentially highly seismogenic region. Based on bathymetric and seismic data, the mechanisms of the deformation at the origin of the onshore and offshore fault networks are explained by the dynamics imposed by the lower plate and those resulting from the migration of the Calabrian Arc and the oceanic accretionary prism towards the Southeast
Crustal rheology of southern Tibet constrained from lake-induced viscoelastic deformation
International audienc
Evolution of a drainage network in collisional context - Insights from experimental modeling of the Southern Alps, New Zealand
Laboratory models of river pattern evolution over a deforming template - Application to the Southern Alps, New Zealand
Structural and tectono-stratigraphic review of the Sicilian orogen and new insights from analogue modeling
International audienceThe Apennines-Sicilian-Maghrebian fold-and-thrust belt originated from the subduction of the Alpine Tethys and the later collision of drifted continental blocks against the African and Apulian paleomargins. From North to South, the Sicilian Fold-and-Thrust Belt (SFTB) is divided in four main tectono-stratigraphic domains: (1) the Calabro-Peloritan
Slip distribution of the 29 December 2020 Mw 6.4 Petrinja earthquake (Croatia) from dense geodetic benchmarks and optical image correlation measurements
International audienceThe intracontinental Mw 6.4 Petrinja earthquake (Croatia) of December 29th, 2020, is one of the strongest earthquakes recorded in slowly deforming Eastern Europe. In low strain contexts, sparse seismic monitoring and the rare occurrence of strong earthquakes often prevent the detailed analysis of coseismic rupture. Discontinuous right-lateral coseismic surface rupture and extensive damages reported in the area suggest a relatively shallow seismogenic source for the Petrinja earthquake. Here, we leverage dense near field measurements from optical image correlation and numerous geodetic benchmarks for cadastral and engineering purposes to model the surface and subsurface slip distribution of the Petrinja earthquake. Optical image correlation based on pre-event (7th December 2017) WorldView and post-event (12th and 20th February 2021) Pleiades satellite images is used to refine the trace of the segmented surface rupture and derive coseismic displacements in the very near-field ( 3 m, is localized on the northern section at depth < 5 km. In conclusion, this study not only provides new constrains on the seismogenic source of the Petrinja earthquake, it also underlines the potential of optical image correlation and cadastral GNSS measurements to retrieve a dense surface displacement field in the epicentral area of moderate intracontinental earthquakes
Deep Origin of the DomeâShaped Hyblean Plateau, Southeastern Sicily: A New TectonoâMagmatic Model
International audienceSoutheastern Sicily is characterized by a prominent topography known as the Hyblean Plateau. It is commonly considered as a flexural bulge formed by the northwest plunging of the HybleanâMalta platform beneath the Sicilian Fold and Thrust Belt. However its noncylindrical shape and multiphase uplift history correlated to the Late Miocene and PlioâPleistocene volcanism outline a possible magmatic control on the Hyblean Plateau topographic expression. We argue, using 2âD flexural models, that the flexural bending alone is unlikely to explain the high anomalous elevation of the Hyblean Plateau. Moreover, topographic analysis show that the Hyblean Plateau has a dome shape composed of radially tilted preserved surfaces defining individual blocks. The block edges seem to be related to deepâseated inherited faults. Using an analogue modeling approach, we show that magmatic intrusions beneath the thick MesoâCenozoic sedimentary cover can reproduce the firstâorder morphology of the Hyblean Plateau when a structural inheritance is imposed. Accordingly, we propose a tectonoâmagmatic model that favors mafic sill intrusions as the major uplift source for the topographic anomaly. However, to explain the strong positive Bouguer anomaly, a deeper highâdensity intracrustal body is needed. Moho uprising related to Mesozoic rifting or mafic lower crust underplating/intraplating since the Late Cretaceous can be evoked. The small wavelength of the topography and the deep intracrustal mass anomaly makes the lithospheric elastic stresses sufficiently high to maintain a nonisostatic state over the geological time scales
Present-Day Surface Deformation of Sicily Derived From Sentinel-1 InSAR Time-Series
International audienceThe Quaternary geodynamics of the Central Mediterranean region is controlled by the migration of narrow orogenic belts within the slow Nubia-Eurasia plate convergence. As testified by the occurrence of major volcanic and seismic events, the Eastern Sicilian Margin is presently one of the most active regions. Using a Permanent-Scatterer approach, we process Sentinel-1 satellite images acquired from 2015 to 2020 to provide an island-wide quantification of surface displacements at a high spatiotemporal resolution. We then convert the calculated mean surface velocities along the ascending and descending satellite line of sight into the ITRF2014 reference frame by using GNSS velocity data derived from regional stations. The resulting pseudo-3D velocity field mainly highlights a general uplift of about 1.5 ± 0.5 mm/yr of the Nebrodi-Peloritani range and its differential motion with respect to mainland Sicily along the CefalĂč-Etna seismic zone. Permanent/Persistent-Scatterer (PS) vertical velocities in the Eastern Hyblean region reveal a long wavelength eastward downbending of the margin, including the inferred epicentral area of the 1693 Noto earthquake. Compared to Quaternary coastal uplift rates, these results confirm the relative low activity of Western Sicily, a potential slow uplift of South-Central Sicily and a significant discrepancy along the Eastern Hyblean margin were PS-derived vertical velocities that appear 2-3 mm/yr lower than the Quaternary rates. Over the 2015-2020 timespan, transient processes are also captured, notably on Mount Etna, showing both magmatic pressurization uplift and collapse of the eastern flank, but also all over Sicily where numerous gravitational mass movements and anthropogenic ground subsidence are detected