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    • Livre
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    Tectonique et géodynamique actuelle de l'arc alpin : approche sismotectonique et modélisation numérique

    Delacou, Bastien
    [Neuchâtel] : [éditeur non identifié]
    2004
    Disponible
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    Titre: Tectonique et géodynamique actuelle de l'arc alpin : approche sismotectonique et modélisation numérique / Bastien Delacou
    Auteur: Delacou, Bastien
    Editeur: [Neuchâtel] : [éditeur non identifié]
    Date: 2004
    Collation: 249 p. : ill. ; 30 cm
    Sujet RERO: Géodynamique - Tectonique - Alpes centrales (chaîne) - ouest
    Note: Th. géosciences Neuchâtel et Nice, 2005 - Existe aussi en version électronique
    No RERO: R003819330
    Existe sous différentes formes: Tectonique et géodynamique actuelle de l'arc alpin
    Permalien:
    http://data.rero.ch/01-R003819330/html

    • Article
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    Active strike-slip faulting in the Chablais area (NW Alps) from earthquake focal mechanisms and relative locations

    Delacou, Bastien
    In: Eclogae geologicae Helvetiae. - Basel. - Vol. 98(2005), no 2, p. 189-199 : fig., cartes
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    Titre: Active strike-slip faulting in the Chablais area (NW Alps) from earthquake focal mechanisms and relative locations / Bastien Delacou, Nicholas Deichmann, Christian Sue, François Thouvenot, Jean-Daniel Champagnac & Martin Burkhard
    Auteur: Delacou, Bastien
    Sujet RERO: Tectonique - Séismes - Chablais (France) - Chablais (Suisse)
    Publication en relation: In: Eclogae geologicae Helvetiae. - Basel. - Vol. 98(2005), no 2, p. 189-199 : fig., cartes
    Document hôte: Eclogae geologicae Helvetiae : recueil périodique de la Société géologique suisse = Mitteilungen der Schweiz. geologischen Gesellschaft
    No RERO: R003968790
    Permalien:
    http://data.rero.ch/01-R003968790/html

    • Article
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    Brittle orogen-parallel extension in the internal zones of the Swiss Alps (South Valais)

    Champagnac, Jean-Daniel, Sue, Christian, Delacou, Bastien, Burkhard, Martin, 1957-2006
    In: Eclogae geologicae Helvetiae. - Basel. - Vol. 96(2003), no 3, p. 325-338 : ill
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    Titre: Brittle orogen-parallel extension in the internal zones of the Swiss Alps (South Valais) / Jean-Daniel Champagnac, Christian Sue, Bastien Delacou & Martin Burkhard
    Auteur: Champagnac, Jean-Daniel; Sue, Christian; Delacou, Bastien; Burkhard, Martin, 1957-2006
    Sujet RERO: Tectonique - Géologie - Failles (géologie) - Alpes (chaîne) - Valais (Suisse)
    Publication en relation: In: Eclogae geologicae Helvetiae. - Basel. - Vol. 96(2003), no 3, p. 325-338 : ill
    Document hôte: Eclogae geologicae Helvetiae : recueil périodique de la Société géologique suisse = Mitteilungen der Schweiz. geologischen Gesellschaft
    No RERO: R003580202
    Permalien:
    http://data.rero.ch/01-R003580202/html

    • Article
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    Les Alpes en mouvement

    Frei, Pierre-Yves
    Champagnac, Jean-Daniel, Delacou, Bastien, Sue, Christian
    Horizons. - 2004/12/22-24
    2004
    Disponible
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    Aucune localisation rattachée
    Titre: Les Alpes en mouvement
    Auteur: Frei, Pierre-Yves
    Contributeur: Champagnac, Jean-Daniel; Delacou, Bastien; Sue, Christian
    Date: 2004
    Description: A l'Université de Neuchâtel, trois géologues apportent des indices troublants sur l'existence d'un mouvement d'extension dans la haute chaîne alpine. Serait-ce un signe de tassement ?
    Publication en relation: Horizons. - 2004/12/22-24
    Document hôte: Horizons
    Identifiant: (DOI)

    • Article
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    Present-day geodynamics in the bend of the western and central Alps as constrained by earthquake analysis

    Delacou, Bastien
    Sue, Christian, Champagnac, Jean-Daniel, Burkhard, Martin
    Geophysical Journal International. - 2004/158/2/753-774
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    Titre: Present-day geodynamics in the bend of the western and central Alps as constrained by earthquake analysis
    Auteur: Delacou, Bastien
    Contributeur: Sue, Christian; Champagnac, Jean-Daniel; Burkhard, Martin
    Sujet: active tectonics - buoyancy forces - earthquake focal mechanisms - orogen-perpendicular extension - stress inversion - western/central Alps
    Description: The contrasted tectonics of the western/central Alps is examined using a synthesis of 389 reliable focal mechanisms. The present-day strain regime is mapped and interpolated for the entire Alpine belt based on a newly developed method of regionalization. The most striking feature is a continuous area of extension which closely follows the large-scale topographic crest line of the Alpine arc. Thrusting is observed locally, limited to areas near the border of the Alpine chain. A majority of earthquakes within the Alps and its forelands are in strike-slip mode. Stress inversion methods have been applied to homogenous subsets of focal plane mechanisms in order to map regional variations in stress orientation. The stress state is confirmed to be orogen-perpendicular both for s3 in the inner extensional zones and s1 in the outer transcurrent/transpressional zones. Extensional areas are well correlated with the part of the belt which presents the thickest crust, as shown by the comparison with the Bouguer anomaly and the average topography of the belt. In the northwestern Swiss Alps, extension is also correlated with currently uplifting zones. These observations and our strain/stress analyses support a geodynamic model for the western Alps in which the current activity is mostly a result of gravitational ‘body' forces. Earthquakes do not provide any direct evidence for ongoing convergence in the Alpine system, but a relationship with ongoing activity of complex block rotations of the Apulian microplate cannot be ruled out
    Publication en relation: Geophysical Journal International. - 2004/158/2/753-774
    Document hôte: Geophysical Journal International
    Identifiant: 10.1111/j.1365-246X.2004.02320.x (DOI)

    • Article
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    Origin of the current stress field in the western/central Alps : role of gravitational re-equilibration constrained by numerical modeling

    Delacou, Bastien
    Sue, Christian, Champagnac, Jean-Daniel, Burkhard, Martin
    Deformation Mechanisms, Rheology and Tectonics : from Minerals to the Lithosphere. - 2005/243/295-310
    2005-05-20
    Disponible
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    Aucune localisation rattachée
    Titre: Origin of the current stress field in the western/central Alps : role of gravitational re-equilibration constrained by numerical modeling
    Auteur: Delacou, Bastien
    Contributeur: Sue, Christian; Champagnac, Jean-Daniel; Burkhard, Martin
    Date: 2005-05-20
    Description: We interpret the strain and stress fields of the western / central Alpine arc on the basis of 2.5D finite element modelling and a recent seismotectonic synthesis. Models have fixed boundary forces and different crustal geometries, so that they respond to buoyancy forces (variations in gravitational potential energies). The seismotectonic regime, characterized by orogen-perpendicular extension in the high topographic core of the belt and local orogen-perpendicular compressional / transpressional deformation in the external zones, appears to be very close to the modelled gravitarional regime. Rotation of Apulia has a minor effect on the current strain or stress fields of the Alpine realm. Nevertheless, it could help to explain the orogen-parallel dextral faulting that is observed all along external zones, from the northern Valais to the Argentera external crystalline massif. Our results highlight the consequences for the Alpine realm of ongoing convergence between the African and European plates. Our interpretation is that collision is no longer ongoing and that buoyancy-driven stresses dominate the present-day geodymamics of the western / central Alps.
    Publication en relation: Deformation Mechanisms, Rheology and Tectonics : from Minerals to the Lithosphere. - 2005/243/295-310
    Document hôte: Deformation Mechanisms, Rheology and Tectonics : from Minerals to the Lithosphere
    Identifiant: (DOI)

    • Article
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    Brittle deformation in the inner NW Alps : from early orogen-parallel extrusion to late orogen-perpendicular collapse

    Burkhard, Martin
    Champagnac, Jean-Daniel, Delacou, Bastien, Sue, Christian
    Terra Nova. - 2004/16/232-242
    2004
    Disponible
    Plus…
    Aucune localisation rattachée
    Titre: Brittle deformation in the inner NW Alps : from early orogen-parallel extrusion to late orogen-perpendicular collapse
    Auteur: Burkhard, Martin
    Contributeur: Champagnac, Jean-Daniel; Delacou, Bastien; Sue, Christian
    Date: 2004
    Description: Internal parts of the Alps have undergone widespread extensional deformation in the course of their Neogene exhumation history. Palaeostress inversion methods are used to map the prevailing stress fields and their evolution through time. Here we present new data from 100 sites with a total of about 2000 faults/striae couples, covering a large portion of the inner north-western Alps. Palaeostress tensors are mostly extensional, although one-third of them are transcurrent. The dominant direction of minimum horizontal stress axes (3) is in an orogen-parallel (N30° to N70°) orientation around the bend of the north-west alpine arc. A comparison between this older (Neogene, post-metamorphic) stress field with the current stress and strain field determined from seismotectonics and geodesy indicates a change in deformation mode from early orogen-parallel extrusion to a late and ongoing orogen-perpendicular spreading.
    Publication en relation: Terra Nova. - 2004/16/232-242
    Document hôte: Terra Nova
    Identifiant: 10.1111/j.1365-3121.2004.00555.x (DOI)

    • Article
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    Active strike-slip faulting in the Chablais area (NW Alps) from earthquake focal mechanisms and relative locations

    Delacou, Bastien, Deichmann, Nicholas, Sue, Christian
    Eclogae geologicae Helvetiae, 2005, Vol.98(2), p.189 [Revue évaluée par les pairs]
    e-periodica (Swiss Electronic Academic Library Service (SEALS))
    Disponible
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    Titre: Active strike-slip faulting in the Chablais area (NW Alps) from earthquake focal mechanisms and relative locations
    Auteur: Delacou, Bastien; Deichmann, Nicholas; Sue, Christian
    Sujet: Geology
    Description: Byline: Bastien Delacou (1), Nicholas Deichmann (2), Christian Sue (1), Francois Thouvenot (3), Jean-Daniel Champagnac (1), Martin Burkhard (1) Keywords: Western Alps; Chablais; Prealpes; seismotectonics; relative location; active faulting Abstract: The Chablais area is characterized by a complex geological setting, resulting from the transport of nappes of various internal origins (the Prealpine nappes), thrusted in Oligocene times onto the Helvetic cover of the external zones of the Alps. While the structural setting and timing of nappe emplacement are well understood, current tectonics and associated faulting remain unclear. The detailed analysis of the Bonnevaux and SamoA<<ns earthquakes, presented in this study, constitutes a significant contribution to the active tectonics of the Chablais area. The associated seismotectonic regime appears to be constant with depth, both focal mechanisms yielding a strike-slip regime, one in the crystalline basement at around 17 km depth and the other probably cross-cutting the cover/basement interface at around 5km depth. Relative location techniques, applied in this study to the seismic sequence associated to the SamoA<<ns earthquake, represents the best way to identify active faults in a region where neotectonic evidence is scarce and controversial. The resulting seismic alignment corresponds to the E-W oriented nodal plane inferred from the SamoA<<ns main shock focal mechanism, thus defining an active near vertical E-W dextral fault. This strike-slip regime, compared to the current regional stress field, corresponds to the one observed in the Jura/Molasse basin area but contrasts with the exclusively dextral and NE-SW-oriented transcurrent regime of the Wildhorn/Martigny region. Abstract (French) La region du Chablais est caracterisee par une configuration geologique et structurale complexe, resultant de la mise en place de nappes de charriage de provenances variees (nappes Prealpines) chevauchantes sur les unites externes Helvetiques durant l'Oligocene. Alors que l'historique de la mise en place de ces nappes est bien compris, le regime tectonique actuel reste a definir. L'analyse detaillee des seismes de Bonnevaux et de SamoA<<ns presentees dans cette etude donne une bonne image du regime tectonique actuel de cette region. Le regime sismotectonique associe a ces seismes apparait stable en fonction de la profondeur, de type decrochant, l'un au niveau du socle cristallin (17 km de profondeur), l'autre intersectant probablement l'interface socle/couverture (5 km de profondeur). Les techniques de relocalisations relatives, appliquees dans cette etude dans le domaine temporel sur la sequence sismique associee au choc de SamoA<<ns, representent le meilleur, si ce n'est l'unique, moyen d'identifie des failles actives dans une region ou les indices neotectoniques sont rares et controverses. L'alignement sismique ainsi defini correspond au plan nodal E-W du mecanisme au foyer du choc principal, permettant de definir une faille dextre, subverticale, orientee E-W. Ce regime decrochant, replace dans son contexte tectonique regional, correspond a celui observe dans la region Jura/Plateau Molassique, caracterise par un systeme de decrochements conjugues (dextre oriente E-W, senestre oriente NW-SE) et contraste avec celui exclusivement dextre, oriente NE-SW, observe au niveau de l'alignement Wildhorn/Martigny. Abstract (German): Das Chablaisgebiet zeichnet sich durch einen komplexen geologischen Aufbau aus, welcher Resultat des Transportes eines aus Einheiten unterschiedlicher interner Herkunft aufgebauten Deckenstapels (die voralpinen Decken) ist, der im Oligozan uber die helvetische Bedeckung der externen Zone des Alpenbogens geschoben wurde. Wahrend strukturgeologischer Aufbau und zeitlicher Ablauf der tektonischen Bewegungen relativ gut bekannt sind, bleiben die tatsachlichen Verschiebungen und die damit verbundene Bruchtektonik weitgehend unklar. Die in der vorliegenden Studie im Detail untersuchten Erdbeben von Bonnevaux und SamoA<<ns ergeben ein ziemlich genaues Bild der aktiven Tektonik im Gebiet des Chablais. Das damit verbundene seismotektonische Regime erscheint in Abhangigkeit der Tiefe konstant. Die Herdmechanismen beider Erdbeben deuten auf ein Blattverschiebungsregime hin, wobei eines im kristallinen Sockel in ca. 17 km Tiefe lokalisiert wurde und das andere hochstwahrscheinlich die Ubergangsszone zwischen Bedeckung und Sockel in ca. 5 km Tiefe uberschneidet. Die in dieser Studie angewendeten relativen Lokalisierungstechniken (in der Zeitdomane) fur die seismische Sequenz des SamoA<<ns-Erdbebens reprasentieren den besten (wenn nicht den einzigen) Ansatz zur Identifizierung aktiver Bruche in einer Region in welcher neotektonische Indizien sparlich vorhanden und kontrovers sind. Die Ausrichtung der daraus resultierenden seismischen Linie ist in guter Ubereinstimmung zu der dextralen E-W orientierten Verwerfung, welche dem Herdmechanismus entnommen werden kann. Dieses Regime ist gut mit dem regionalen Stressfeld und der aktiven Tektonik im Gebiet Jura/Molassebecken vergleichbar, unterscheidet sich aber deutlich vom rein dextralen NE-SW gerichteten Blattverschiebungsregime im Gebiet Wildhorn/Martigny. Author Affiliation: (1) Institut de Geologie, Universite de Neuchatel, rue Emile Argand 11, CP-2, CH-2007, Neuchatel, Switzerland (2) Swiss Seismological Service, ETH-ZA>>rich, CH-8093, Zurich, Switzerland (3) Laboratoire de Geophysique Interne et Tectonophysique (LGIT), Maison des Geosciences, CNRS/UJF, Campus Universitaire, 1381 rue de la Piscine, BP 53, FR-38041, Grenoble Cedex 1, France Article History: Registration Date: 01/01/2005 Online Date: 23/11/2005 Article note: Manuscript received February 5, 2005 Revision accepted August 14, 2005
    Fait partie de: Eclogae geologicae Helvetiae, 2005, Vol.98(2), p.189
    Identifiant: 0012-9402 (ISSN); 1420-9128 (E-ISSN); 10.5169/seals-169170 (DOI)

    • Article
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    Brittle orogen-parallel extension in the internal zones of the Swiss Alps (South Valais)

    Champagnac, Jean-Daniel, Sue, Christian, Delacou, Bastien
    Eclogae geologicae Helvetiae, 2003, Vol.96(3), p.325 [Revue évaluée par les pairs]
    e-periodica (Swiss Electronic Academic Library Service (SEALS))
    Disponible
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    Titre: Brittle orogen-parallel extension in the internal zones of the Swiss Alps (South Valais)
    Auteur: Champagnac, Jean-Daniel; Sue, Christian; Delacou, Bastien
    Sujet: Geology
    Fait partie de: Eclogae geologicae Helvetiae, 2003, Vol.96(3), p.325
    Identifiant: 0012-9402 (ISSN); 1420-9128 (E-ISSN); 10.5169/seals-169024 (DOI)

    • Dissertation
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    Current tectonic and geodynamic setting of the alpine arc - Insights from seismotectonics and numerical modelling

    Delacou, Bastien
    Hyper Article en Ligne (CCSd), Hyper Article en Ligne Open Access (CCSd)
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    Titre: Current tectonic and geodynamic setting of the alpine arc - Insights from seismotectonics and numerical modelling
    Auteur: Delacou, Bastien
    Date: 09 December 2004
    Sujet: Sciences of the Universe ; Earth Sciences ; Applied Geology ; Sciences of the Universe ; Earth Sciences ; Geophysics ; Sciences of the Universe ; Earth Sciences ; Tectonics ; Sciences of the Universe ; Earth Sciences ; Tectonics ; Seismotectonics ; Alps ; Numerical Modelling ; Geodynamics ; Geodesy ; Tectonique ; Sismotectonique ; Alpes
    Description: The current tectonic regime of the western/central Alps is examined from the compilation of a synthetic database of 389 focal mechanisms. This synthesis reveals the major role of extensionnal tectonics, characterising the whole 'high' core of the belt. The directions of extension are orogen-perpendicular in these areas, while fan-shapped directions of compression are found in external domains, in a general transcurrent mode of deformation (shifted locally to extension or compression).br /A model of gravitationnal re-equilibration is advanced and tested with finite element numerical modellings, firstly in 2.5D and secondly in 2D (ECORS profile). These modelling studies reveal the major role of gravitationnal body forces, producing a tectonic regime close to the one analysed in our seismotectonic analysis and interpreted as a current post-collisionnal setting in the western/central alpine belt.br /Quantifications of deformation show slow deformations, of the...