Pratique d’une activité physique de loisir chez les patients atteints de sclérose en plaques en région Centre-Val de Loire

International audienc

Imagerie sismique de la zone de collision hercynienne dans le Sud-Est du Massif armoricain (projet Armor 2/programme Géofrance 3D)

The structure of the Hercynian collision zone in the southeast of the Armorican Massif is illustrated by a 70-km long deep seismic profile acquired in September 2000. The profile images a previously unknown south-dipping thrust that brought the Champtoceaux Domain on top of the Central Armorican Domain during Carboniferous times. Dextral strike-slip motions along the South Armorican Shear Zone, which is downward cut by the thrust zone, are partly coeval with northward thrusting. A major discontinuity, hidden by the thrust front, is also imaged in the lower crust between the Champtoceaux area and the Central Armorican Domain. These new data lead to a structural and kinematic re-interpretation of this part of the Hercynian collision zoneLa structure de la zone de collision hercynienne dans le Sud-Est du Massif armoricain est illustrée par un profil sismique en écoute longue de 70 km de long, acquis en septembre 2000. Le profil met en évidence une structure chevauchante à vergence nord, inconnue jusqu'à présent, qui fait chevaucher, pendant le Carbonifère, le domaine de Champtoceaux sur le domaine Centre-Armoricain. Les déplacements décrochants dextres le long du cisaillement Sud-Armoricain, recoupé à sa base par le chevauchement, sont au moins en partie synchrones des mouvements chevauchants vers le nord. Une discontinuité majeure, oblitérée par le front du chevauchement, est mise en évidence entre le domaine de Champtoceaux et le domaine Centre-Armoricain. Ces données nouvelles conduisent à une profonde ré-interprétation structurale et cinématique de cette portion de la collision hercynienn

Notice explicative Carte géol. France (1/50 000), feuille Argelès-sur-Mer – Cerbère (1097). Orléans : BRGM, 189 p. Carte géologique par Calvet M., Autran A., Wiazemsky M., Laumonier B., Guitard G. (✝) (2014).

Notice de la Carte géologique de Franc

Carte géologique de la France à 1:50 000. 5, Marquise

Document cartographique, 2eme édition ;Ellipsoïde de Clarke, amorce du quadrillage kilométrique UTM, amorce des quadrillages kilométriques Lambert. - Fond topographique IGN. Carte de base : Carte topographique de la France à 1:50 000, feuille 210

Tectonic and sedimentary architecture of the Karukera spur: A record of the Lesser Antilles fore-arc deformations since the Neogene

International audienceThe Karukéra spur is an easternmost submerged rise of the Lesser Antilles fore-arc in the Guadeloupe archipelago, culminating about 4000 m above the fore-arc basin 150 km west of the deformation front. The analysis of 3500 km 2D high-resolution multichannel seismic reflection and multibeam bathymetric data, and the study of 14 core samples, allow for the first time to reconstruct its sedimentary anatomy and tectonic evolution. Seven seismic units (US1 to US7) are evidenced, organised into four major depositional sequences separated by erosional surfaces. Units US1 to US4 thicken to the south-southeast on the spur. The sedimentary deposits rest upon a deeply eroded metamorphic basement of the Caribbean Plate as in La Désirade Island. Sequence 1 (units US1 and US2) remains unknown in its lower part because it does not outcrop. Its upper part comprises early Miocene shallow water carbonates. Sequence S2 (Unit US3) only comprises an upper Miocene transgressive systems tract deposited into basinal environment. It is bounded by major erosional surfaces SB2 and SB3. Sequence 3 (US4 to US6) is Zanclean to Pleistocene. It is dominantly composed of shallow water, reefal deposits. Sequence 4 corresponds to recent deposits. The Karukéra spur experienced three main extensional episodes with alternations between uplift and subsidence periods. Uplifts are responsible for emersions and erosions. Subsidence severely drowned shallow water deposits. The first extensional episode led to the formation of horsts and grabens in the basement, prior to early Miocene deposits. The second extensional episode occurred during upper Miocene, in accordance with data in surrounding islands. The third tectonic episode developed since Calabrian. Noticeable is the constant reactivation of N130°–N150°, N150°–N180° and N40° trending faults since early Miocene and the neoformation of E–W trending faults since Calabrian. Our results suggest that at the latitude of Guadeloupean archipelago the Lesser Antilles subduction zone is an erosional margin because of the successive sweepings of the Santa Lucia then Tiburon Ridges