Foreword
The venue of the Variscan 2015 conference at the University Rennes, and its theme, "correlations and plate dynamics", are the occasion to recall that, some 40 years ago, was convened in this university (25 September to 6 October 1974), under the aegis of CNRS and IGCP-UNESCO, an international meeting entitled: “La Chaîne varisque d'Europe moyenne et occidentale”. Thanks to large scale correlations, the purpose of this conference was namely to build a synthetic geodynamic reconstruction of the Variscan (or Hercynian) orogen. Although numerous recent studies emphasize the continuing advancement in the knowledge of the environment and processes that are at the origin of the Variscan belt, today we are still trying to reach a convincing and acceptable synthesis.
Let us remember that, in the 1970s, in spite of the ideas already established by Suess, Kossmat and Stille about the Variscan zonation in Central Europe, the first attempts of reconstructions using plate tectonics concept were essentially performed on the Alpine belt. Both modern and traditional views on the Variscan belt were proposed at the 1974 meeting, where coexisted, on the one hand, plate tectonic reconstructions and, on the other, geosynclines. In the same time, geochronological data started to be easily available and thus contributed to better constrained models.
Among the main topics discussed were: i) the reworking of the Precambrian in the Variscan orogen because a better knowledge of the basement of the Paleozoic sediments prior to the Variscan tectonics was considered to be an absolute prerequisite to decipher the complexity of Variscan structures; ii) the eoVariscan period where the first geochronological data shed light on the importance of the magmatic events between 500 and 400 Ma, that were quite underestimated up to that moment. The first essays to apply plate tectonics models to the Devonian paleogeography led to different interpretations that questioned the place, the position and the direction of the subduction zones; iii) in the main Variscan regions, different reconstructions proposed to bridge the gap between the dismembered segments. A test was carried out on the Southern Variscan Branch using late Variscan strike slips postdating the opening of oceanic zones between continental blocks, and iv) the non European Paleozoic chains, Urals, Mauritanides and Appalachians, were also considered and correlations proposed.
Most of these issues are still topical at present, as exemplified by the contributions to the present conference. Concurrently, new concepts allow alternative views of the processes involved in building the orogen. As an example, the consideration of the Varisan orogen as an assemblage of successively accreted magmatic arcs rather than a collision of large continents allows to better explain some of the observed geological features. The concept of subduction rollback as an explanation of the juxtaposition of high-pressure rocks with migmatite complexes is another example. New geochronological methods help to better constrain the metamorphic and magmatic events and understand some existing data in a different way, etc. We could possibly regret the almost complete lack of contribution dealing with the sedimentary record of the Carboniferous-Permian times that could shed a different light on the understanding of the orogen. The involvement of this aspect into the research of the Variscan belt should in our opinion be particularly encouraged in the future.
The first day of the present meeting deals with the geology of some of the key regions of the orogeny and examines how the gap between regional discrete information on dispersed fragments can be filled to arrive to a general seamless and coherent Variscan reconstruction from Morrocco to the Bohemian Massif passing through the Iberian peninsula, the Pyrénées, Corsica and Sardinia, the Alps, the French Massif Central, Armorican Massif and other less studied regions like the Turkish Pontides.
The second day, more thematic, examines the history from the pre-Variscan heritage to the Variscan oceans and arcs, subduction environment and the related HP metamorphism, and processes underwent from the collision to the collapse of the orogen.
The morning of the third day is devoted to the granite magmatism so characteristic of the Variscan orogeny, and its relationship with ore genesis, an important topic if one keeps in mind that the Industrial revolution in the XIXth century was made possible thanks to the Variscan ores and carbon and that European economy could still draw some benefits from these resources.
Pavel Pitra et Philippe Rossi
Contribution list
Aerden D., Sayab M. Porphyroblast inclusion trail: the key to Variscan correlations between Iberia, Armorica and beyond
Aertgeerts G., Lorand J.P., Monnier C., Lahondère D., La C. New petrological constraints on amphibolites and serpentinised peridotites from the variscan Champtoceaux Complex, southern Armorican Massif, France
Aguilar C., Montserrat L., Reche J., Štípská P., Schulmann K., Muñoz J.A., Casas J.M, Powell R. Open-system processes during decompression: An example from contact aureole migmatites from the Roc de Frausa Massif (Eastern Pyrenees)
Aretz M., Herbig H.G. The palaeogeographical position of the Eastern Moroccan Meseta in Mississippian times: new data and model from the Jerada Massif (NE Morocco)
Avigad D., Rossi P., Gerdes A. Origin of "Pan-African" micaschist from Variscan Corsica: detrital zircon U-Pb-Hf constrains on provenance and Cadomian paleogeography
Ballèvre M. How fresh-water bivalves record the growth and collapse of the Variscan belt
Ballouard C., Poujol M., Jolivet M., Dubois C., Hallot E., Boulvais P., Tartèse R., Dabard M.P., Ruffet G. Geochronological and thermochronological constraints on the Carboniferous magmatism of the Armorican Massif: from the source to the exhumation.
Baptiste J., Martelet G., Faure M., Beccaletto L., Perrin J. Up-to-date regional gravity and aeromagnetic data to unravel the geological patterns of the pre-Mesozoic substratum of the Paris Basin
Bouenitela V., Ballèvre M. Migmatite xenoliths and garnet xenocrysts in the Pouldu microgranitic dykes: (Southern Armorican Domain, western France): a window into the lower crust.
Broska I., Bezak V., Petrik I. Genesis and tectonic evolution of the West-Carpathian Variscan granites
Calassou T., Závada P., Schulmann K., Hasalová P., Štípská P. Microstructural and anisotropy of magnetic susceptibility records of a granite intrusion in Bohemian massif (Central Sudettes, Variscan orogenic belt)
Casini L., Maino M., Cuccuru S., Funedda A., Oggiano G., Puccini A., Rossi P. Early Permian necking of the Corsica-Sardinia massif
Castro A., Pereira F., Fernández C. Granite magmatism of the European Variscan belt. An overview
Chardon D., Roques D., Aretz M. Kinematic reappraisal of nappe tectonics and late orogenic sedimentation in the Southern French Massif Central
Chelle-Michou C., Laurent O., Moyen JF., Block S., Gardien V., Paquette J.L., Couzinié S. New U-Pb and Hf zircon data from the eastern Massif Central: From Gondwana to Pangea in a nutshell
Cochelin B., Chardon D., Denèle Y., Gumiaux C., Le Bayon B. Variscan strain field and kinematics of the Pyrenees
Coke C., Dias R., Amaral F., Romão J., Ribeiro A. Cambro-Ordovician unconformities in the Central Iberian zone : extensional or compressional process ?
Couzinié S., Laurent O., Moyen J.F., Zeh A., Vézinet A., Villaros A. Mg-K magmatic suites as a tool to scan the composition of the Variscan orogenic mantle, case studies from the French Massif Central
Cruciani G., Franceschelli M. Amphibole-bearing migmatite from NE Sardinia (Italy) and its constraints on Variscan partial melting
De Poulpiquet J. Is the magnetic Ibero-Armorican arc the trace of a Cambro-Ordovician aborted rift ?
Dewey J. Ophiolite Enigma resolved?
Dias R., Moreira N., Ribeiro A. Dextral strike-slip tectonics in Iberia and the Pangeia Assemblage: evidences of the Tardi-Variscan Deformation event in South Portuguese Zone
Dias R., Ribeiro A., Coke C., Moreira N., Romão J. Central Iberian Arc : just a model ?
Dias Da Silva Í., Gonzalez-Clavijo E., Diez-Montes A. Lateral escape tectonics in the Variscan Orogen: A new approach for the emplacement of the Allochthonous terranes and for the birth of the Central Iberian Orocline.
Duchêne S., Samalens N., Severac J.L., Driouch Y., Ntarmouchant A., Dahire M. A window to the crust below Moroccan Massif Central: high temperature crustal xenoliths trapped in Permian lavas
Edel J.B., Schulmann K. Paleomagnetic constraints on the evolution of the Variscan belt in Carboniferous-Permian times
Eguiluz L., Martinez-Torres L.M., Sarrionadia F., Carracedo M., Gil Ibarguchi I. The Ibero-Armorican Belt: an evolving island-arc along northern Gondwana between ca. 650 and 480 Ma
Eguiluz L., Sarrionadia F., Martinez-Torres L.M., Carracedo M., Gil Ibarguchi J.I. Variscan evolution of the Ibero-Armorican Belt
Faure M., Rossi P., Li X., Fréville K., Melleton J., Lin W. Variscan orogeny in the Eastern Variscan Branch: New structural and geochronological insights from Corsica and surrounding areas
Franceschelli M., CRUCIANI G., MONTOMOLI C., CAROSI R., PUXEDDU M. A review of Variscan metamorphism and deformation in northern Sardinia, Italy
Franke W. Variscan oceans: how many, where and when?
Fréville K., Faure M., Trap P., Melleton J., Blein O., Li X. Petro-structural evolution of the Belledonne massif: Implications for the Variscan orogenic evolution
Friedel C.H. Geothermobarometry of very low-grade Devonian metabasalts of the Elbingerode Complex (Harz Mountains, Germany) - implications of chlorite and phengite composition
Friedel C.H., Huckriede H., Leiss B., Zweig M. Sedimentary vs. tectonic mélanges – a case study from the Harz Mountains (eastern Rhenohercynian Belt)
Galy C., Vanderhaeghe O. When a partially molten orthogneiss meets a syntectonic granite along the Northern flank of the Canigou massif, Axial Zone of the Pyrenees
Gloaguen E. Ore deposits around the Ibero-Armorican arc and their relations to the Variscan orogeny
Gomez-Barreiro J., Duran Oreja M., Martinez Catalan J. R., Gonzalez Clavijo E., Diez Montes A. The sole thrust of the Lower Allochthon to the west of the Morais Complex (Portugal): Correlation with the Lalín-Forcarei thrust in the Órdenes Complex (Spain).
Gutierrez-Alonso G., Fernandez-Suarez J., Henderson B., Pastor-Galan D., Lopez Carmona A., Murphy J.B., Weil A.B., Pereira M.F. , Fernandez-Lozano J. Another model for the Western Europe Paleozoic Variscan evolution: questioning redundant subduction and oceans
Hasalova P. Pervasive melt flow in the continental crust: examples from Variscan Orogeny
Janak M. Variscan metamorphic evolution of the Western Carpathians: Tatric and Veporic units
Karaoui B., El Ouardi H., Mahmoudi A. Evidence of E-W dextral shear zones in the Bas Draâ inlier (Western Anti Atlas, Morocco): Macro - to microtectonic arguments and geodynamic implications
Kretschmer S., Franke W., Wemmer K., Königshof P., Gerdes A. Tectono-metamorphic evolution of the Mouthoumet Massif (S-France): interference of orogenic accretion and anorogenic crustal extension
Kroner U., Romer R.L., Hallas P., Stephan T. Extrusion tectonics from an intracontinental subduction zone: The late orogenic granites of the Saxo-Thuringian Zone
Kunz B.E., Manzotti P., Von Niederhäusern B., Burn M., Giuntoli F., Engi M. Permian high-temperature metamorphism in continental units of the Western Alps (Italy)
Labrousse L., Duretz T, Ganzhorn A.C., Gerya T. Partial melting and continental subduction: coupling metamorphic reactions and collisional dynamics
Laurent O., Couzinie S., Vanderhaeghe O., Zeh A., Moyen J.F., Villaros A., Gardien V. U–Pb dating of Variscan igneous rocks from the eastern French Massif Central: southward migration of coeval crust- and mantle- melting witnesses late-orogenic slab retreat
Lemirre B., De Saint Blanquat M., Duchêne S., Poujol M. Signification of the late-Variscan high temperature event: a view from the Pyrenees
Li B., Massonne H.J P-T evolution of Variscan high-pressure rocks from the Northern Malpica-Tuy shear zone in NW Spain
Linnemann U. The Cadomian orogen: constraints of timing, orogenic zoning, and crustal growth based on U-Pb and Hf isotpes of detrital and magmatic zircon
Lom N., Can Ülgen S., Özgül N., Sunal G., İşseven T., Natal’in B.A., Celâl Şengör A.M. The eastern extent of the Hercynian orogenic belt: The history of the Istanbul Zone before and during the assembly of the Pangaea
López-Carmona A., Abati J., Pitra P., Lee J.K.W., Gutiérrez-Alonso G., Fernández-Suárez J. High-pressure rocks in the Variscan belt of Western Europe: the Malpica-Tui Complex (NW Iberian Massif)
López-Carmona A., Rubio Pascual F.J., Arenas R. P–T constraints in the internal domains of the Variscan Orogen through pseudosection modelling: the Barrovian section of Somosierra (Central Iberian Massif)
Lotout C., Pitra P., Poujol M., Ruffet G., Tondella E., Van Den Driessche J. Variscan subduction of an Ordovician granite : the Lévézou Massif, French Massif Central
Maierová P., Schulmann K., Guillot S., Lexa O., Štípská P., Čadek O., Janoušek V. Linking PT evolutions of Bohemian Massif and Tibetan granulites through numerical modelling: insight to geodynamics of internal orogens
Manzotti P., Ballèvre M., Poujol M. Detrital zircon gochronology in blueschist facies meta-conglomerates from the Western Alps: implications for the late Carboniferous to early Permian palaeotopography
Martinez Catalan J. R., Gonzalez Clavijo E., Meireles C., Diez Fernández R., Bevis J. Detrital zircon U-Pb ages in Variscan syn-orogenic deposits of NW Iberia: Relationships between sedimentation and emplacement of the Allochthon
Melleton J., Gloaguen E. Timing of rare-elements (Li-Be-Ta-Sn-Nb) magmatism in the European Variscan belt
Moreira N., Pedro J.C., Romão J., Dias R., Araújo A., Ribeiro A. The Neoproterozoic-Cambrian transition in Abrantes Region (Central Portugal): Litostratigraphic correlation with Cambrian Series of Ossa-Morena Zone
Moyen J.F., Couzinié S., Mintrone M., Vanderhaeghe O., Chelle-Michou C., Laurent O., Block S., Gardien V., Paquette J.L., Zeh A., Poujol M. Rifting the Gondwana: record of a ultra-thinned continental margin in the French Massif Central
Nardin E., Chardon D., Aretz M., Berger J., Poujol M. Ordovician reorganization of the European Gondwana: Towards an integrated magmatic – sedimentary – structural scheme across the Variscan domain
Okay A.I., Topuz G. Variscan orogeny in the Pontides, northern Turkey
Pereira I., Dias R., Bento dos Santos T., Mata J. Figueira de Castelo Rodrigo – Lumbrales Anatectic Complex (Iberia): the role of shearing on exhuming high grade rocks
Peresty V., Lexa O., Jerabek P. The effect of rheology on the strain partitioning in the crustal section at the western margin of the Teplá-Barrandian Unit
Pérez-Caceres I., Martinez Poyatos D.J., Fernando Simancas J., Azor A. Structural and geochronogical advances in the Variscan evolution of SW Iberia
Pochon A., Gapais D., Gumiaux C., Branquet Y., Gloaguen E., Cagnard F., Martelet G. Geographical and lithological relationships between high-density magnetic lithologies and Variscan Sb ± Au mineralizations in the Armorican belt (France)
Rahimi G., Massonne H.J. Petrology and age-dating of a Variscan garnet-bearing micaschist from the northern Fichtelgebirge, Germany
Regorda A., Marotta A.M., Roda M., Lardeaux J.M., Spalla M.I. Effects of mantle hydration and viscous heating on the dynamics of mantle wedge in a subduction system: differences and similarities of 2D model predictions with examples from the Variscan crust
Ribeiro M.A., Areias M., Ferreira J., Martins H., Sant’Ovaia H. Geological and petrological constraints on the variscan evolution of the NW area of Port-Viseu Belt
Romer R.R., Kroner U. Chemical character of Variscan granites of the Saxo-Thuringian Zone
Rubio Pascual F. J, Martin Parra L. M, Diez Montes A., Diez Fernandez R., Gallastegui G., Valverde Vaquero P., Rodriguez Fernandez L R., Heredia N Metamorphic records of partial subduction and continental collision in and around the parautochthon of the NW Iberian Massif
SEGHIR E.M., El Ouardi H., Lindhorst J., Chaponniere P., Kamburov D. The structural control of the tin mineralisation at the Bou El Jaj project (NE of the central Hercynian massive)
Siman P., Hirata T. I – Type tonalite Evolution: new isotopic and geochronological ICP –MS / TIMS data interpretation from the Central Western Carpathians, Slovakia.
Soares A., Dias R. Fry and RF/Φ strain methods constraints and fold transection mechanisms; an example of progressive deformation in the Iberian Variscides
Stephan T., Hallas P., Kroner U., Buske S. Crustal-scale 3D modelling of the Allochthonous Domain of the Saxo-Thuringian Zone: constraints from high-resolution 2D seismic profiles
Stremtan C.C., Ryan J. G., Savov I. Mantle-crust interaction recorded in the latest Variscan plutons of the Romanian Southern Carpathians
Teyssier C., Whitney D.L, Roger F., Rey P.F., Trap P. Coeval eclogitization and migmatization during orogenic collapse (Montagne Noire dome)
Thiéblemont D. High-Sr – Low-Yb (“adakitic”) Namuro-Westphalian peraluminous granites from South-Brittany: evidence for high-pressure crustal melting at the “collapse stage” of the Variscan orogen
Thiéry V., Rolin P., Dubois M., Goncalves P. New UHP evidences from the inner part of the Variscan belt: geology of the Chavanon sequence, French Massif Central
Topuz G. Early to Late Carboniferous granite and gabbro intrusions in the eastern Pontides and its relations with the Variscan Orogeny in the Central Europe
Trap P., Cenki-Tok B., Roger F., Rabin M., Fréville K., Carry N., Paquette J.L. Strain partitioning during migmatitic dome formation in the Variscan Montagne Noire massif (Southern French Massif Central)
Wafik A., Traoré K., Nzaou Mabika N., Saquaque A. Contribution to the geological and metallogeneny study of Bakoudou Golden Ore Deposit (Gabon)
Warren C., Mottram C. M., Mcdonald C.S., Regis D. Progress and pitfalls in linking age to stage in metamorphic rocks
Wernert P., Štípská P., Chopin F., Schulmann K., Bosch D., Bruguier O., El Houicha M., Corsini M., Ghienne JF. Tectonometamorphic evolution of the intracontinental orogeny exemplified by the Rehamna massif (Morocco, Variscan belt)
Závada P., Jeřábek P., Hasalová P., Racek M., Konopásek J., Lexa O.
Extrusion of anatectic lower crust from orogenic infrastructure: an example from the Eger crystalline unit (Bohemian Massif, Czech Republic)
Zucali M., Spalla I., Roda M., Zanoni D. Pre-Alpine contrasting tectono-metamorphic evolution within the Southern Steep Belt (Central Alps)
Zurbriggen R. Metagreywacke gneiss terranes rich in peraluminous granitoids – indications for a unique type of early Paleozoic orogeny
Dernière mise à jour le 04.09.2015