Manioc : Portail | resultats 241 - 260 pour la recherche: montagnes

Saint-Pierre. La Place Bertin après la catastrophe du 8 mai 1902
Auteur(s) : Benoit-Jeanette, A.
Année de publication :

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La Soufrière. Piton du nord

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Maison ou est né le poète Bertin. (isle de la Réunion)

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Coulée de la Rivière-Sans-Nom
Auteur(s) : Tardon d'Aste
Année de publication :

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Fig. 16 Nevis, as seen from the southwest. The young cone is built are seen in Saddle and Cone mountains.

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Le Tumuc-Humac au sud du Mont Mitaraca
Auteur(s) : Riou, Édouard (1833-1900)

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Coulée de la Rivière-Blanche. 15 Décembre 1929
Année de publication :

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Timing of formation and exhumation of the Montagne Noire double dome, French Massif Central
Auteur(s) : Roger, Françoise Teyssier, Christian Respaut, Jean-Patrick Rey, Patrice F. Jolivet, Marc Whitney, Donna, Paquette, Jean-Louis Brunel, Maurice
Auteurs secondaires : Géosciences Montpellier ; Université des Antilles et de la Guyane (UAG) - Institut national des sciences de l'Univers (INSU - CNRS) - Université de Montpellier (UM) - Centre National de la Recherche Scientifique (CNRS) Department of Geology and Geophysics (DGG) ; University of Minnesota [Minneapolis] School of Geosciences ; The University of Sydney [Sydney] Géosciences Rennes (GR) ; Université de Rennes 1 (UR1) - Institut national des sciences de l'Univers (INSU - CNRS) - Observatoire des Sciences de l'Univers de Rennes (OSUR) - Centre National de la Recherche Scientifique (CNRS) Laboratoire Magmas et Volcans (LMV) ; Université Blaise Pascal - Clermont-Ferrand 2 (UBP) - Institut national des sciences de l'Univers (INSU - CNRS) - Université Jean Monnet [Saint-Étienne] (UJM) - Centre National de la Recherche Scientifique (CNRS)

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
New U–Pb monazite, zircon, and xenotime ages date the Late Carboniferous crystallization of the anatectic Vialais granite in the Montagne Noire Axial Zone and the high-temperature deformation and metamorphism of the augen gneiss (Ordovician granite protolith) from which the granite was likely derived. The U–Pb monazite ages obtained from the augen gneiss (308 ± 3 Ma), late kinematic Vialais granite (303 ± 4 Ma), and post-kinematic leucogranite (298 ± 2 Ma), bracket the high-temperature deformation and metamorphism at ~ 310–300 Ma, clearly postdating regional contraction and nappe emplacement (> 320 Ma). The planar–linear and locally linear fabrics in the augen gneiss outline a regional-scale double dome structure (Caroux and Espinouse sub-domes) containing smaller (km-scale) upright folds. Compared to the Caroux sub-dome, the larger, migmatitic Espinouse sub-dome contains abundant leucosome, leucogranite bodies and late-kinematic intrusions (Vialais granite). The Vialais granite displays a weak magmatic foliation that defines the main layering of the Espinouse migmatite. Ellipsoidal quartz–sillimanite nodules concentrated above the roof of the granite recorded an increment of strain (vertical shortening, E–NE elongation) during granite emplacement and crystallization, consistent with the extension event that exhumed the domes. These new geochronological and structural data suggest that the Montagne Noire double dome formed in a pull-apart structure within a dextral strike–slip system. Upright folding in the sub-domes has been traditionally assigned to a regional contraction event; alternatively, we propose that local contraction is associated with the convergence of low-viscosity crust beneath the upper crust pull-apart. Dynamic models of extension of hot crust indicate that contraction at depth is generated by flow of low-viscosity orogenic crust converging and rising to fill the gap created by upper crust extension. This interpretation solves the long-standing problem of apparent coeval contraction and extension in the Montagne Noire double dome and establishes migmatite dome emplacement in strike–slip corridors as a style of late Variscan tectonics.
ISSN: 0040-1951

insu-01112009
https://hal-insu.archives-ouvertes.fr/insu-01112009
DOI : 10.1016/j.tecto.2014.12.002

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