On the post-25 Ma geodynamic evolution of the western Mediterranean

We present a tectonic synthesis and an animation of the tectonics of the western Mediterranean since the Oligocene. This work is based on data derived from different geological datasets, such as structural geology, the distribution of metamorphic rocks, magmatic activity, sedimentary patterns, palaeomagnetic data and geophysics. Reconstruction was performed using an interactive software package (PLATYPLUS), which enabled us to apply rotational motions to numerous microplates and continental terranes involved in the evolution of the western Mediterranean basins. Boundary conditions are provided by the relative motions of Africa and Iberia with respect to Europe, and the Adriatic plate is considered here as an African promontory. The reconstruction shows that during Alpine orogenesis, a very wide zone in the interface between Africa and Europe underwent extension. Extensional tectonics was governed by rollback of subduction zones triggered by gravitational instability of old and dense oceanic lithosphere. Back-arc extension occurred in the overriding plates as a result of slow convergence rates combined with rapid subduction rollback. This mechanism can account for the evolution of the majority of the post-Oligocene extensional systems in the western Mediterranean. Moreover, extension led to drifting and rotations of continental terranes towards the retreating slabs in excess of 100-800 km. These terranes - Corsica, Sardinia, the Balearic Islands, the Kabylies blocks, Calabria and the Rif-Betic - drifted as long as subduction rollback took place, and were eventually accreted to the adjacent continents. We conclude that large-scale horizontal motions associated with subduction rollback, back-arc extension and accretion of allochthonous terranes played a fundamental role during Alpine orogenesis.

Reconstruction of the tectonic evolution of the western Mediterranean since the Oligocene

Alluvial deposits of the Guadalope-Matarranya system (Oligocene, Ebro basin, Spain) and the Wasatch Formation (Eocene, western Colorado), provide time-integrated records of the process of river-channel avulsion. These sequences consist of isolated channel-belt sandstones incised into, and abruptly overlain by, flood-plain siltstones, indicating deposition by avulsive river systems. The geometry and distribution of channel incisions suggest that avulsion was not controlled by tectonics, climate, or base-level changes, but formed by autocyclic processes. Measurements from 221 channel fills in the Guadalope-Matarranya system and 38 from the Wasatch Formation allow us to statistically characterize channel geometries we infer to be associated with establishment and abandonment of individual river avulsions. Paleoflow depths in both systems average 1.4 to 1.6 m. Aggradation height (superelevation) of channel margin levees are, on average, 0.6 and 1.1 times paleoflow depth in the Guadalope-Matarranya and Wasatch systems, respectively. These results are consistent with values from recently avulsed modern rivers and suggest that (1) flow depth is the appropriate parameter against which to scale the critical superelevation necessary for channel avulsion; and (2) the increase in potential energy due to channel perching drives the lateral instability that is needed for avulsion to be successful. Numerous stacked channel fills indicate repeated reoccupation of the same site by avulsing channels. These reoccupation channels indicate that inherited flood-plain topography, here abandoned channel forms, was an important control on the arrival site of newly avulsed channels. Comparison of our results to others suggests two end-member types of avulsion can take place. Incisional avulsion, seen here, is characterized by an early incision phase followed by infilling by migrating bar forms. Aggradational avulsion begins with aggradation followed in time by stream integration into a single downcutting channel. We suggest that the type of avulsion is strongly influenced by whether or not the adjacent flood plain is well or poorly drained. In both cases subsequent aggradation and channel perching increase the chances that some triggering event will lead to avulsion.

Interpreting avulsion process from ancient alluvial sequences: Guadalope-Matarranya system (northern Spain) and Wasatch Formation (western Colorado)

The role of slab detachment processes in the opening of the western–central Mediterranean basins: some geological and geophysical evidence

One - Printed Volume.- 1 The Mediterranean Area and the Surrounding Regions: Active Processes, Remnants of Former Tethyan Oceans and Related Thrustbelts.- Abstract.- 1.1 Introduction.- 1.2 Mediterranean Fold-and-thrust Belts.- 1.3 Mediterranean Marine Basins.- 1.4 Geological-geophysical Baseline.- 1.4.1 Heat Flow.- 1.4.2 Crustal and Lithospheric Structure.- 1.4.3 Gravity.- 1.4.4 Magnetic Field.- 1.4.5 Seismicity.- 1.4.6 Geodetic Data.- 1.4.7 Stress Field.- 1.5 Global Dynamics and Active Processes Exemplified in the Mediterranean.- 1.5.1 Subduction of the Eastern Mediterranean Lithosphere beneath the Calabrian and Aegean.- 1.5.2 Rifting and Passive Margin Development in Back-arc Regions and Other MediterranRelated to Tectonic Wedges, Tilted Blocks and Sedimentary Loadingean Domains.- 1.5.3 Mud and Salt Diapirism (Eastern Mediterranean Ridge, Alboran Sea, Nile Delta).- 1.5.4 Sea-level Changes, Salinity Crisis, Flooding (Messinian Mediterranean versus Pleistocene Black Sea).- 1.6 Record of Ancient Dynamics of the Tethyan Oceans, Ophiolitic Sutures, Mantle Tomography versus Paleogeography of the Mediterranean Realm.- 1.6.1 Collisional vs. Intracontinental Thrust Belts and Oceanic Sutures.- 1.6.2 Plate Dynamics and Palinspastic Restorations: Demise of the Concept of a Single Tethys.- 1.6.3 Cenozoic Magmatism in the Mediterranean Region.- 1.7 Conclusions.- Acknowledgements.- 2 A Tomographic View on Western Mediterranean Geodynamics.- Abstract.- 2.1 Introduction.- 2.2 The Global Tomography Model BS2000.- 2.3 Interpretation of Model BS2000 for the Western Mediterranean Mantle.- 2.3.1 Alps, Apennines, and the Western Mediterranean.- 2.3.2 The Betic-Rif and Alboran Region.- 2.4 Analysis: the Geodynamic Evolution of the Western Mediterranean.- 2.4.1 Tomographic Evidence for Slab Roll-back.- 2.4.2 Northern Apennines and Alpine-Tethys Subduction.- 2.4.3 Slab Detachment beneath the Central-southern Apennines.- 2.4.4 Calabria Subduction.- 2.4.5 The North African Margin.- 2.4.6 Betic-Rif and Alboran Region: I. Subduction and Roll-back of Predominantly Oceanic Lithosphere.- 2.4.7 Betic-Rif and Alboran Region: II. Development of Arc Geometry and Subduction Roll-back.- 2.4.8 Synthesis of Tomographic Constraints on the Geodynamic Evolution of the Western Mediterranean Region.- 2.5 Summary.- Acknowledgements.- Appendix 1 (CD-ROM).- Appendix 2 (CD-ROM).- 3 The TRANSMED Transects in Space and Time: Constraints on the Paleotectonic Evolution of the Mediterranean Domain.- Abstract.- 3.1 Introduction.- 3.2 The Western Tethys Main Plate Tectonic Constraints.- 3.2.1 The East Mediterranean-Neotethys Connection.- 3.2.2 The Apulia-Adria Problem.- 3.3 The Geodynamic Evolution of Greater Apulia and Surrounding Regions.- 3.3.1 Paleotethys Evolution (Figs. 3.2-3.6).- 3.3.2 Cimmerian Events and Triassic Marginal Oceans (Figs. 3.6-3.9).- 3.3.3 The Jurassic Oceans: Alpine Tethys, Central Atlantic and Vardar (Figs. 3.8-3.11).- 3.3.4 The Cretaceous Oceans: North Atlantic and the Pyrenean Domain (Figs. 3.10-3.14).- 3.4 The TRANSMED Transects in Space and Time.- 3.4.1 Transects I-II-III West.- 3.4.2 Transects IV-V-VI.- 3.4.3 Transects III East, VII and VIII.- 3.5 Conclusions.- Acknowledgements.- Appendix 3 (CD-ROM).- References: Preface, Chapters 1, 2 and 3.- References: CD-ROM.- Transect I: Iberian Meseta - Guadalquivir Basin - Betic Cordillera - Alboran Sea - Rif - Moroccan Meseta - High Atlas - Sahara Domain.- Transect II: Aquitaine Basin - Pyrenees - Ebro Basin - Catalan Coastal Ranges - Valencia Trough - Balearic Promontory - Algerian Basin - Kabylies - Atlas - Saharan Domain.- Transect III: Massif Central - Provence - Gulf of Lion - Provencal Basin - Sardinia - Tyrrhenian Basin - Southern Apennines - Apulia - Adriatic Sea - Albanian Dinarides - Balkans - Moesian Platform.- Transects IV, V and VI: The Alps and Their Forelands.- Transect VII: East European Craton - Scythian Platform - Dobrogea - Balkanides - Rhodope Massif - Hellenides - East Mediterranean - Cyrenaica.- Transect VIII: Eastern European Craton - Crimea - Black Sea - Anatolia C2014 Cyprus - Levant Sea - Sinai - Red Sea.

The transmed atlas : the mediterranean region from crust to mantle : geological and geophysical framework of the mediterranean and the surrounding areas

La chaine iberique et la chaine cotiere catalane se sont developpees durant le Paleogene par l'inversion des rifts mesozoiques. Ces rifts appartiennent au systeme de bassins de la plate-forme peri-tethysienne nord-occidentale. Celle-ci a evolue pendant l'ouverture de la Tethys alpine et de l'Atlantique nord, a la suite de la rupture de la Pangee. Le bassin iberique s'est developpe durant le cycle de rifting du Permien superieur-Trias en meme temps que l'ouverture des systemes de rift de la Tethys et de l'Arctique-Atlantique nord vers l'ouest et le sud, respectivement. Pendant le Jurassique superieur et moyen, l'evolution du bassin iberique a ete controlee par une subsidence thermique post-rift. Le magmatisme alcalin, Trias superieur a Jurassique moyen, qui est evident dans le sud-est du bassin iberique, s'est produit probablement en relation avec la plume magmatique de l'Atlantique central. Le rifting a recommence pendant l'Oxfordien superieur et a persiste jusqu'au debut de l'Albien superieur. Ce cycle de rifting peut etre subdivise en trois pulsations qui ont controle le developpement des bassins de Cameros, Maestrat, Columbrets et iberique sud-occidental. Il n'existe pas de preuves de magmatisme syn-rift au Cretace inferieur. Ce deuxieme cycle de rifting coincide avec une activite similaire dans le domaine de l'Atlantique nord et culmine durant l'Aptien moyen avec la separation entre l'Iberie, l'Amerique du Nord et l'Europe. L'ouverture des bassins oceaniques de l'Atlantique nord et du Golfe de Gascogne ont eu lieu aussi durant cette etape. De l'Albien superieur au Maastrichtien, le bassin iberique a subside en reponse a la re-equilibration thermique post-rift de la lithosphere. La contraction intraplaque s'est produite en Iberie cratonique a la suite de la collision pyreneenne et des premieres phases de l'orogenese Betique. Ceci a controle ensuite le developpement des chaines iberique et cotiere catalane durant l'Eocene et l'Oligocene moyen. Le raccourcissement total de l'ecorce durant le Paleogene en chaine iberique est estime d'environ 75 km soit environ 20%, et a ete responsable de la formation d'une racine de 43 km de profondeur. Cette etude est basee sur une analyse pluridisciplinaire qui integre des donnees de sismique reflexion et de sondage, la biostratigraphie, la sedimentologie, la stratigraphie sequencielle, l'analyse de subsidence, la geologie structurale, ainsi que des donnees de gravite, magnetiques, et de sismique refraction.

Evolution of the Mesozoic Central Iberian Rift System and its Cainozoic inversion (Iberian chain)

The Neogene structure of the eastern Iberian margin: Structural constraints on the crustal evolution of the Valencia trough (western Mediterranean)

Evolution of the central Catalan margin of the Valencia trough (western Mediterranean)

During the Palaeogene Alpine compression three units were differentiated in the studied area (south of the Ebro Basin): the Catalan Coastal Range, dominated by NE–SW major basement faults with a sinistral movement; The Iberian Range, where the important basement faults have a NW–SE direction and a reverse movement (often with a dextral component); the Linking Zone, between these two ranges, where an E–W dominant structural direction is marked by an array of folds and thrusts (with a northward vergence) in the Mesozoic cover.From the analysis of both these major structures and the small-scale structures, it can be deduced that the compression in the studied area has evolved from a NW–SE direction (lower-middle Eocene) to a N–S direction and to a NE–SW one (uppermost Oligocene). The major structures are due to the N–S compression. Later, the stress-field progressively changed to a distensive regime.We suggest a relation between the compressive phases and the displacement direction of the Iberian Plate with reference to the European Plate.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756800029940

Joan Guimerà

Papers

Evolution of the Mesozoic Central Iberian Rift System and its Cainozoic inversion (Iberian chain)

The Neogene structure of the eastern Iberian margin: Structural constraints on the crustal evolution of the Valencia trough (western Mediterranean)

Evolution of the central Catalan margin of the Valencia trough (western Mediterranean)

Palaeogene evolution of deformation in the northeastern Iberian Peninsula

Paleogene Strike-Slip Deformation and Sedimentation Along The Southeastern Margin of the Ebro Basin