A new look at old debates about the Corbières (NE-Pyrenees) geology: salt tectonics and gravity gliding

In the Corbières area, a large-scale nappe has been identified at the beginning of the 20th century: the “Nappe des Corbières Orientales” (NCO) resting over a thick Triassic sole. This geological object is located at the NE of the Pyrenees, close to the Gulf of Lions. At this place, the chain changes in orientation from E-W to NE-SW and presents in detail, a great complexity. The existence of the nappe itself has never been contested. However, due to its overall complexity, several controversies exist regarding the style and chronology of deformation of its substratum in the so-called the “Pinède de Durban” in particular. We show that the new concepts of salt tectonics can clarify these old debates. Indeed, the rise of the Triassic salt during Mesozoic rifting episodes results in the development of characteristic sedimentary sequences (halokinetic sequences) on top of salt walls. It is along one of these, coinciding with the prolongation of the Cévenole Fault System, that the NCO has been individualized. During its Cenozoic emplacement, a gravity-gliding component, explaining the importance of the observed translation, could result from an uplift preceding the rifting at the origin of the Gulf of Lions

Extensional vs contractional Cenozoic deformation in Ibiza (Balearic Promontory, Spain): Integration in the West Mediterranean back-arc setting

Based on field work and seismic reflection data, we investigate the Cenozoic tectono-sedimentary evolution offshore and onshore Ibiza allowing the proposal of a new tectonic agenda for the region and its integration in the geodynamic history of the West Mediterranean. The late Oligocene-early Miocene rifting event, which characterizes the Valencia Trough and the Algerian Basin, located north and south of the study area respectively, is also present in Ibiza and particularly well-expressed in the northern part of the island. Among these two rifted basins initiated in the frame of the European Cenozoic Rift System, the Valencia Trough failed rapidly while the Algerian Basin evolved after as a back-arc basin related to the subduction of the Alpine-Maghrebian Tethys. The subsequent middle Miocene compressional deformation was localized by the previous extensional faults, which were either inverted or passively translated depending on their initial orientation. Despite the lateral continuity between the External Betics and the Balearic Promontory, it appears from restored maps that this tectonic event cannot be directly related to the Betic orogen, but results from compressive stresses transmitted through the Algerian Basin. A still active back-arc asthenospheric rise likely explains the stiff behavior of this basin, which has remained poorly deformed up to recent time. During the late Miocene a new extensional episode reworked the southern part of the Balearic Promontory. It is suggested that this extensional deformation developed in a trans-tensional context related to the westward translation of the Alboran Domain and the coeval right-lateral strike-slip movement along the Emile Baudot Escarpment bounding the Algerian Basin to the north. (C) 2016 Elsevier B.V. All rights reserved

Extreme Mesozoic crustal thinning in the Eastern Iberia margin: The example of the Columbrets Basin (Valencia Trough)

Eastern Iberia preserves a complex succession of Mesozoic rifts partly or completely inverted during the Late Cretaceous and Cenozoic in relation with Africa-Eurasia convergence. Notably, the Valencia Trough, classically viewed as part of the Cenozoic West Mediterranean basins, preserves in its southwestern part a thick Mesozoic succession (locally ≈10 km thick) over a highly thinned continental basement (locally only ≈3.5 km thick). This subbasin, referred to as the Columbrets Basin, represents a Late Jurassic-Early Cretaceous hyperextended rift basin weakly overprinted by subsequent events. Its initial configuration is well preserved allowing us to unravel its 3-D architecture and tectonostratigraphic evolution in the frame of the Mesozoic evolution of eastern Iberia. The Columbrets Basin benefits from an extensive data set combining high-resolution seismic reflection profiles, drill holes, seismic refraction data, and expanding spread profiles. The interactions between halokinesis, involving the Upper Triassic salt, and extensional deformation controlled the architecture of the Mesozoic basin. The thick uppermost Triassic to Cretaceous succession displays a large-scale 'syncline' shape, progressively stretched and dismembered toward the basin borders. We propose that the SE border of the basin is characterized by a large extensional detachment fault acting at crustal scale and interacting locally with the Upper Triassic décollement. This extensional structure accommodates the exhumation of the continental basement and part of the crustal thinning. Eventually, our results highlight the complex interaction between extreme crustal thinning and occurrence of a prerift salt level for the deformation style and tectonostratigraphic evolution of hyperextended rift basins

Les reliques téthysiennes en Méditerranée orientale: les bassins Ionien, d'Hérodote et du Levant

National audienc

Géodynamique du nord de l'Algérie

CERGY PONTOISE-BU Neuville (951272102) / SudocSudocFranceF

Le relief des Atlas marocains (contribution des processus asthénosphériques et du raccourcissement crustal, aspects chronologiques)

Le but de cette thèse est l étude des mouvements verticaux et la caractérisation des processus à l origine de ces mouvements au sein d une chaîne de montagnes intracontinentale. Le Haut Atlas au Maroc culmine à plus de 4000 m à 500 km au Sud de la limite de plaque. Nous montrons que deux processus sont à l origine d un tel relief. Un amincissement de la lithosphère explique 1000 m de la topographie du Haut Atlas, de l Anti-Atlas et du Moyen Atlas. Sa géométrie est allongée NE-SW. Le raccourcissement crustal est le deuxième mécanisme à l origine de ces reliefs. Il s exprime sous la forme de structures variées en raison d une stratigraphie mécanique contrastée, contrôlée par l héritage structural complexe de cette région. Une approche thermochronologique combinée aux données géologiques m a permis d établir une chronologie des mouvements verticaux liés à deux phases de raccourcissement (Eocène Sup. et Plio-Quaternaire) et à l amincissement lithosphérique (Miocène Inférieur à Moyen).We focus on vertical movements and processes at their origin in an intracontinental mountain belt. The High Atlas belt, situated at more than 500 km from the plate boundary, culminates at more than 4000 m. Two mechanisms explain this relief. A lithospheric thinning explains 1000 m of the High Atlas, Anti Atlas and Middle Atlas belts relief. The thinned area is elongated in a NE/SW direction. Crustal shortening is the second process at the origin of the relief of the belts. In the High Atlas, a wide variety of structures can be observed. I show that the complex structural inheritance led to the development of multiple décollement levels. A thermochronological approach, combined with the geological data, allows me to propose the chronology of the vertical movements in the belts and their foreland. Two tectonic phases took place during Upper Eocene and Plio-Quaternary, and the uplift related to the thinning of the lithosphere occurred during Lower to Middle Miocene.CERGY PONTOISE-BU Les Cerclades (951272104) / SudocCERGY PONTOISE-BU Neuville (951272102) / SudocSudocFranceF

Couplages socle-couverture et style de la déformationau front des orogènes (Comparaison entre le Minervois (front des Pyrénées, France) et le Potwar (front de l'Hymalaya, Pakistan))

CERGY PONTOISE-BU Les Cerclades (951272104) / SudocSudocFranceF