7 research outputs found
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 â10 km thick) over a highly thinned continental basement (locally only â3.5 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 dĂ©collement. 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
Valencia basin at the boundary between the Iberian and Mediterranean domains : tectono-sedimentary evolution from the Mezoique to the Cenozoique
Le Bassin de Valence, situĂ© Ă lâest de lâIbĂ©rie et sĂ©parĂ© du Bassin AlgĂ©rien par le Promontoire BalĂ©ares, rĂ©sulte dâune Ă©volution polyphasĂ©e dans lâespace et dans le temps. Son histoire cĂ©nozoĂŻque, celle dâun bassin dâarriĂšre-arc Oligo-MiocĂšne, est Ă prĂ©sent reconnue. Toutefois cette extension se surimpose Ă plusieurs phases de rift observĂ©es Ă terre du Permien au CrĂ©tacĂ© infĂ©rieur. Cette histoire plus ancienne demeure mĂ©connue en mer malgrĂ© son importance dans lâhĂ©ritage structural du bassin. Au sud du Bassin de Valence, le Bassin de Columbrets en tĂ©moigne en rĂ©vĂ©lant dâĂ©paisses sĂ©quences mĂ©sozoĂŻques jusquâalors incluses dans un « socle acoustique » indiffĂ©renciĂ©. Ce domaine permet donc le dĂ©chiffrage du mĂ©canisme des Ă©vĂšnements tectoniques qui se sont succĂ©dĂ© du MĂ©sozoĂŻque Ă lâEst de lâIbĂ©rie dâune part, au CĂ©nozoĂŻque en MĂ©diterranĂ©e occidentale dâautre part.BasĂ© sur une stratĂ©gie dâĂ©tude terre-mer, ce travail vise une meilleure comprĂ©hension (1) des processus tectoniques tertiaires modelant le sud du Bassin de Valence et la MĂ©diterranĂ©e occidentale (2) de la rĂ©ponse sĂ©dimentaire Ă des processus dâextension et dâhyper-extension au MĂ©sozoĂŻque (3) de lâimportance de lâhalocinĂšse lors la mise en place des structures sĂ©dimentaires et tectoniques.LâĂ©tude structurale dâIbiza, lâĂźle la plus mĂ©ridionale du Promontoire BalĂ©are, reconsidĂšre le calendrier tectonique de la rĂ©gion ainsi que son intĂ©gration dans lâhistoire gĂ©odynamique de la MĂ©diterranĂ©e occidentale. Le rift Oligo-MiocĂšne dĂ©crit dans le Bassin de Valence et initiĂ© par le SystĂšme de Rifts CĂ©nozoĂŻques EuropĂ©ens a Ă©tĂ© observĂ© sur Ibiza. Cet Ă©vĂšnement est suivi au MiocĂšne Moyen dâune dĂ©formation compressive localisĂ©e par les failles normales prĂ©cĂ©demment formĂ©es. La comparaison avec le calendrier tectonique des Kabylies en AlgĂ©rie montre que cette dĂ©formation compressive, qui Ă©pargne le Bassin AlgĂ©rien, rĂ©sulte de la convergence Europe-Afrique. Des cartes rĂ©tro-tectoniques intĂšgrent ces Ă©vĂšnements dans le contexte gĂ©odynamique de la MĂ©diterranĂ©e occidentale depuis lâOligocĂšne.LâĂ©tude des sĂ©ries MĂ©sozoĂŻques effectuĂ©es Ă terre et en mer (grĂące Ă lâinterprĂ©tation de donnĂ©es sismiques et de forages) rĂ©vĂšle plusieurs phases de rifting du Permien au CrĂ©tacĂ© infĂ©rieur. Un Ă©pisode majeur Jurassique supĂ©rieur Ă CrĂ©tacĂ© infĂ©rieur est Ă lâorigine de lâĂ©paisse sĂ©quence sĂ©dimentaire du Bassin de Columbrets. DocumentĂ©e Ă terre, cette phase ayant conduit Ă lâouverture de la partie sud de lâAtlantique Nord est Ă lâorigine de bassins ibĂ©riques ou pĂ©ri-ibĂ©riques tels Maestrat, CamĂ©ros ou Parentis.Un amincissement majeur de la croĂ»te est visible sous lâĂ©paisse sĂ©quence mĂ©sozoĂŻque, la rĂ©duisant Ă 5km. Le mĂ©canisme dâextension voire dâhyper-extension proposĂ© invoque une faille de dĂ©tachement Ă pendage NW qui sâenracine dans la croĂ»te infĂ©rieure litĂ©e. Une reprĂ©sentation des structures en 3D a Ă©tĂ© rĂ©alisĂ©e afin de comprendre lâĂ©volution du Bassin de Columbrets.Lâarchitecture sĂ©dimentaire du Bassin de Columbrets est Ă©galement contrĂŽlĂ©e par le mouvement des sĂ©ries salifĂšres depuis leur dĂ©pĂŽt au Trias supĂ©rieur jusquâĂ lâactuel. La partie septentrionale du bassin se caractĂ©rise par une halocinĂšse surtout liĂ© aux dĂ©formations extensives de la rĂ©gion. En revanche au sud du front chevauchant des BĂ©tiques, le sel est aussi remobilisĂ© en compression. La gĂ©omĂ©trie et la rĂ©partition des structures salifĂšres dĂ©crites Ă terre et en mer dĂ©pendent fortement de lâĂ©paisseur initiale de la couche de sel dans le bassin; cette observation apporte des Ă©lĂ©ments de rĂ©ponse sur la palĂ©ogĂ©ographie des sĂ©ries du Keuper au sud du Bassin de Valence.Au final cette Ă©tude aborde dâune part des thĂšmes liĂ©s au mĂ©canisme de formation des bassins intracontinentaux et plus particuliĂšrement la relation entre hyper-extension, signature sĂ©dimentaire et halocinĂšse. Dâautre, elle permet une meilleure intĂ©gration du sud du Promontoire BalĂ©are et du Bassin de Valence dans la gĂ©odynamique Ouest- MĂ©diterranĂ©enne.The Valencia Basin, located east of Iberia and separated from the Algerian Basin by the Balearic promontory, underwent a poly-phased tectonic evolution in space and time. The Cenozoic evolution of the basin has been widely discussed, the most classical interpretation being an Oligo-Miocene aborted back-arc basin. However, this extensional tectonic regime postdated several rifting events from the Permian to the Lower Cretaceous. This older evolution remains poorly understood offshore, despite its influence on the tectonic inheritance of the basin. The Columbrets Basin, in the southernmost part of the Valencia Basin, exhibits a thick Mesozoic sequence that was considered to belong to an undifferentiated âacoustic basementâ. Hence, the Columbrets Basin is a key study area to unravel the successive Mesozoic to Cenozoic tectonic events in Eastern Iberia and Western Mediterranean.Our study integrates onshore and offshore data to better constrain (1) the Cenozoic tectonic processes that led to the current morphology of the southern Valencia Basin and the Western Mediterranean (2) the sedimentary records Mesozoic extensional to hyper-extensional processes and (3) the importance of the halokinesis in the sedimentary and tectonic architectures.Ibiza Island, located on the southernmost part of the Balearic Promontory, questions the standard tectonic agenda of the area and its integration in the Western Mediterranean geodynamic frame. The Oligo-Miocene rifting phase described in the Valencia basin is initiated by the European Cenozoic Rift System (ECRIS) and has been observed in Ibiza. This event is followed by a Middle Miocene contractional phase reactivating the inherited normal faults. The comparison with the tectonic history of the Kabylies in Algeria shows that this stage that does not affect the Algeria basin, results from the convergence between Europe and Africa. A set of retro-tectonic maps integrates these events in the geodynamic context of West Mediterranean.The Mesozoic units were studied onshore and offshore (using drilling and seismic data); it reveals several rifting phases from the Permian to the Lower Cretaceous. A major Upper Jurassic to Lower Cretaceous event was responsible for the deposition of the thick sequence present in the Columbrets Basin. This tectonic event led to the opening of the southern part of the north Atlantic but is also at the origin of several Iberian or peri-iberian basins such as Maestrat, Cameros, or Parentis basins.A major crustal thinning has been observed underneath the thick Mesozoic sequence, reducing the crustal thickness to 5 km. The proposed extensional and even hyper-extensional mechanism used a NW dipping detachment fault rooting deeply into the layered lower crust. A 3D geometrical model of the structures illustrates the evolution of the Columbrets Basin.The sedimentary architecture of this basin is also controlled by salt movements from their deposition during the Late Triassic to current times. The northern part of the Basin is characterized by salt movements mainly linked to the extensional deformations of the area. South of the Betics Front, the salt is remobilized by compressional deformations. The geometry and the location of the salt structures described onshore and offshore depend on the initial thickness of the salt in the basin; this observation gives evidence for the paleogeography of the Keuper sequences in the south of Valencia Basin.Finally, this study documents the mechanisms leading to the formation of intracontinental basins and especially the relationships between hyperextension, sedimentary filling and halokinesis. On the other hand, our study allows a better integration of the southern part of the Balearic Promontory and Valencia Basin in the geodynamic frame of the West Mediterranean
Extreme Mesozoic Crustal Thinning in the Eastern Iberia Margin: The Example of the Columbrets Basin (Valencia Trough)
International audienceEastern 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 â10 km thick) over a highly thinned continental basement (locally only â3.5 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 dĂ©collement. 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
Extreme Mesozoic Crustal Thinning in the Eastern Iberia Margin: The Example of the Columbrets Basin (Valencia Trough)
International audienceEastern 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 â10 km thick) over a highly thinned continental basement (locally only â3.5 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 dĂ©collement. 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