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In spite of a clear fan-shaped magnetic anomalies in the Eastern Algero-Balearic Basin (EABB), the way how and the time when seafloor spreading occurred are still debated. In this work, a new seismo-stratigraphic interpretation based on deep-penetration reflection seismic data correlated to reduced-to-the-pole magnetic anomalies and on-offshore litho-stratigraphic correlation of Pre-Messinian units bring new constraints on its age and mode of opening. Our results reveal that the seafloor spreading of the EABB occurred at an intermediate half-spreading rate of 3.7±0.5 cm/yr for 2.45±0.18 Myr during the Langhian-Serravallian times, i.e. after the Corsica-Sardinia block rotation and the collision of Lesser Kabylia with Africa. We revise the kinematics of the Algero- Balearic domain into three stages: (1) birth of a highly stretched continental basin accommodating the southern drift of the Kabylies driven by slab rollback between ∼23 and ∼15 Ma, (2) fast opening of a new EABB between 15.2 and 12.7 Ma by clockwise rotation of a Greater Alboran Block (GALB) promoted by slab tearing, (3) late East-West opening of the western basin in response to the westward retreat of the Gibraltar slab and westward slab tearing propagation and the concomitant migration of the GALB. The last stages match both the late formation of a Subduction-Transform Edge Propagator (STEP) faults at the toes of the Algero-Balearic margins and the post-collisional volcanic migration along the Algerian margin interpreted as related to slab tearing propagation. This new scenario favors a significant stretching and splitting of the GALB into several continental fragments resulting from the westward propagation of the arcuate subduction front by lateral tearing of a narrow slab.

This study aims to bring new constraints on the origin and age of formation of the Algero-Balearic Basin (ABB) and on its pre-Messinian evolution. Based on a seismostratigraphic interpretation of seismic data correlated with reduced to the pole magnetic anomalies and geological records of the Algerian margin, the oceanic crust of the East Algerian Basin (EAB) is dated to the Langhian - Serravallian, showing that this basin postdates the rotation of the Corso-Sardinia block and the collision of the Lesser Kabylia with Africa, with a short (~2.5 Ma) and rapid (half-rate of 3.7 cm/yr) seafloor spreading. A 4-phases evolution is proposed: (1) Aquitanian - Lower Langhian: birth of a back-arc proto-basin by southward drift of the Kabylian blocks driven by the Tethysian slab retreat; 2) Middle Langhian - Lower Serravallian: opening of a new fan-shaped oceanic basin (EAB) by clockwise rotation of the Greater Alboran Block (GAlB) and tearing of the Tethysian slab; (3) Upper Serravallian - Lower Tortonian: post-accretion magmatic activity associated with asthenospheric upwelling induced by slab tear propagation and mantle delamination; (4) Middle Tortonian - Middle Messinian: late opening of the central and western basins by westward retreat of the Gibraltar slab and migration of the GAlB, forming "STEP" (Subduction-Transform Edge Propagator) type margins north and south of the ABB. This evolution explains the late opening of the ABB and the fragmentation of the GAlB into several blocks, testifying to the prominent role of mantle dynamics and slab tearing in the genesis of this back-arc domain., Cette étude vise à apporter de nouvelles contraintes sur l’origine et l’âge de formation du Bassin Algéro-Baléarique (BAB) et sur son évolution pré-messinienne. A partir d’une interprétation sismostratigraphique de données sismiques corrélée aux anomalies magnétiques réduites au pôle et aux témoins géologiques de la marge algérienne, le plancher océanique du Bassin Est-Algérien (BEA) est daté du Langhien - Serravallien, montrant que ce bassin est postérieur à la rotation du bloc corso-sarde et à la collision de la Petite Kabylie avec l’Afrique, avec une accrétion océanique brève (~2,5 Ma) et rapide (demi-taux de ~3,7 cm/an). Une évolution en 4 phases est proposée : (1) Aquitanien - Langhien inférieur : création d’un proto-bassin d’arrière-arc par dérive vers le sud des Kabylides sous l’effet du recul du slab Téthysien; 2) Langhien moyen - Serravallien inférieur : ouverture d’un nouveau bassin océanique en éventail (BEA) par rotation horaire du Bloc du Grand Alboran (BGAl) et déchirure du slab Téthysien; (3) Serravallien supérieur - Tortonien inférieur : activité magmatique post-accrétion liée à des flux asthénosphériques par propagation de la déchirure du slab et délamination mantellique; (4) Tortonien moyen - Messinien moyen : ouverture tardive des bassins central et occidental par recul du slab de Gibraltar vers l’ouest et migration du BGAl, formant des marges de type "STEP" (Subduction-Transform Edge Propagator) au nord et sud du BAB. Cette évolution explique l’ouverture tardive du BAB et la fragmentation du BGAl en plusieurs blocs, témoignant du rôle prépondérant de la dynamique mantellique et de la déchirure des slabs dans la genèse de ce domaine d’arrière-arc.

It is common practice to assume values for basal heat flow or basal temperatures as a lower boundary condition for thermo-kinematic models of crustal tectonics. Here, we infer spatial and temporal variations of the paleo-basal temperature from integrated modelling of thermochronological ages, to relate the inferred variations to the geodynamic setting. To this end, we consider the Argentine Precordillera as a natural laboratory, given that its kinematic evolution is relatively well constrained and therefore, the focus can be placed on the variations of its basal thermal state. By means of a simple Monte Carlo sampling approach with thermochronological data as constraints, we infer the paleo-basal temperature history. This is compared to estimates posed by models existing in the literature concerning flat-slab subduction. Our results imply that, given the kinematic models used to date in the area, extremely low temperature gradients (

International audience; The natural variability of geometry and dynamics of subduction zones leads to a variety of mantle and crustal processes that may influence the genesis of ore deposits in the overriding plate. These complex interactions cannot be fully represented by two-dimensional (2D) models but require that the spatial and temporal evolution of ore deposits be examined in a detailed 3D tectonic framework. We compare and discuss the geodynamic and metallogenic evolution of the eastern Mediterranean subduction zone since the late Cretaceous by integrating a newly compiled metallogenic database with a recent kinematic reconstruction model. The resulting paleotec-tonic maps identify (1) a late Cretaceous Cu-rich metallogenic period with large deposits formed above a linear and stable subduction zone that produced large amounts of potentially fertile magmas in a narrow magmatic arc and (2) a late Eocene-Miocene Pb-Zn-followed by Au-rich metallogenic period with generally smaller deposits spread over a wide back-arc basin that was opened due to subduction retreat and lateral slab tearing. Supported by high-resolution numerical modeling, the proposed dynamic arc and back-arc metallogenic models emphasize (1) the influence of 3D slab dynamics and associated asthenospheric flow on ore distribution in space and time and (2) the importance of exhuming metamorphic domes in extensional back-arc setting to focus metal-bearing fluid circulations. These models differ from collision and post-collision models and may be valid on the western and eastern terminations of the whole Tethyan orogenic belt (i.e. Mediterranean and southeast Asia) where fast 3D subduction dynamics has influenced the geodynamic and metallogenic evolution of the overriding plate.

International audience; The relationship between subduction dynamics and crustal deformation in the Mediterranean region has been recently studied using three-dimensional (3D) numerical models. Such models require, however, a detailed information concerning the past geological evolution. We use stratigraphic, petrologic, metamorphic, structural, paleomagnetic and magmatic data to build new kinematic reconstructions of the eastern Mediterranean region since the late Cretaceous using the principle of non-rigid domains. The motions of the 56 deforming domains defined in this work are calculated based on published paleomagnetic rotations, the directions and amounts of displacement on crustal-scale shear zones and the burial and exhumation histories of the main metamorphic units. Extracted from these reconstructions, paleotectonic maps and lithospheric-scale cross-sections illustrate that the present-day subduction zone has been continuously retreating southward since the late Cretaceous and has accreted several small continental domains in the process. We find evidence for two back-arc-related extensional events: (1) slow extension along the Balkans and the Pontides in the late Cretaceous while the trench was long and linear and (2) faster extension in the Rhodope-Aegean-west Anatolian region since the Eocene-Oligocene. Rapid rotation of the Hellenides between 15 and 8 Ma probably indicates a slab tearing event below western Anatolia that could have further accelerated this extensional kinematics. Spatial distribution and the geochemical signature of magmatic centers integrated in these reconstructions allow us to trace mantle-related processes revealing the deep dynamics that controls both the magma genesis and the crustal deformation.