Manioc : Portail | resultats 1 - 20 pour la recherche: Usine du François

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Iran is an active continental domain accommodating the convergence between the Arabia and Eurasia plates. In northwestern Iran, deformation between the Central Iranian block and the Caucasus domain is mainly accommodated by right lateral strike-slip on the Tabriz fault. Cities and villages, including the city of Tabriz, have been destroyed by several strong historical earthquakes (M similar to 7). In this study, we compare the slip-rates estimated from geodetic measurements (radar interferometry and UPS) with those determined by dating a geomorphological offset of an alluvial fan along the Tabriz fault. The GPS measurements along two profiles normal to the Tabriz fault suggest a slip-rate of 7.3 +/- 1.3 mm yr(-1). The persistent scatterer radar interferometry analysis of Envisat satellite archives from 2003 to 2010 shows a velocity gradient (6 +/- 3 mm yr(-1)) across the Tabriz fault in agreement with GPS results. Moreover, it reveals that most of the area located south of the Tabriz fault is affected by subsidence, and that some sections of the fault probably act as barriers to fluid migration which may have an impact on its mechanical behaviour. West of Tabriz morphotectonic investigations on an alluvial fan surface show a right-lateral cumulative offset of 320 +/- 40 m Luminescence analyses of the coarse matrix alluvial fan deposits provide an age of 46 +/- 3 ka. This yields a slip-rate comprised between 6.5 and 7.3 mm yr(-1) along this segment. These results suggest that the Late Quaternary slip-rate is in agreement with the present-day slip-rate estimated by geodetic measurements, showing no slip-rate changes during the past 45 000 yr. Short-term variations within the 45 000 yr related to temporal earthquake clustering over few seismic cycles cannot be ruled out, but if they exist, they do not affect the geodetic and the geomorphological estimates. This study is in agreement with previous ones suggesting that long-term slip-rates (i.e. averaged over several tens of seismic cycles) are consistent with geodetic estimated slip-rates (i.e. extrapolated from few years of interseismic observations), and suggests that perturbations of fault slip-rates are related to variations over few seismic cycles.
ISSN: 0956-540X

hal-00844695
https://hal.archives-ouvertes.fr/hal-00844695
https://hal.archives-ouvertes.fr/hal-00844695v2/document
https://hal.archives-ouvertes.fr/hal-00844695/file/rizza2013.pdf
DOI : 10.1093/gji/ggt041

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Rapport présenté à l'Assemblée Générale des actionnaires du lundi 20 juillet 1953 - Usine du François
Auteur(s) : Usine du François
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Rapport présenté à l'Assemblée Générale des actionnaires du 17 novembre 1941 - Usine du François
Auteur(s) : Usine du François
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Rapport présenté à l'Assemblée Générale des actionnaires du lundi 25 avril 1960 - Usine du François
Auteur(s) : Usine du François
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Rapport présenté à l'Assemblée Générale des actionnaires du lundi 21 novembre 1949 - Usine du François
Auteur(s) : Usine du François
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Rapport présenté à l'Assemblée Générale des actionnaires du lundi 13 mai 1957 - Usine du François
Auteur(s) : Usine du François
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Contrasted styles of rifting in the eastern Gulf of Aden: A combined wide-angle, multichannel seismic, and heat flow survey
Auteur(s) : Leroy, Sylvie Lucazeau, F. d'Acremont, Elia Watremez, Louise Autin, Julia Rouzo, Stéphane Bellahsen, Nicolas Tiberi, Christel
Auteurs secondaires : Institut des Sciences de la Terre de Paris (iSTeP) ; Université Pierre et Marie Curie - Paris 6 (UPMC) - Centre National de la Recherche Scientifique (CNRS) Institut de Physique du Globe de Paris (IPGP) ; Université Pierre et Marie Curie - Paris 6 (UPMC) - Institut national des sciences de l'Univers (INSU - CNRS) - IPG PARIS - Université Paris Diderot - Paris 7 (UPD7) - Université de la Réunion (UR) - Centre National de la Recherche Scientifique (CNRS) 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 Earth and Environmental Sciences ; University of Rochester [USA] Géoazur (GEOAZUR) ; Université Pierre et Marie Curie - Paris 6 (UPMC) - Université Nice Sophia Antipolis (UNS) ; Université Côte d'Azur (UCA) - Université Côte d'Azur (UCA) - Institut national des sciences de l'Univers (INSU - CNRS) - Observatoire de la Côte d'Azur - Centre National de la Recherche Scientifique (CNRS) Domaines Océaniques (LDO) ; Centre National de la Recherche Scientifique (CNRS) - Institut d'écologie et environnement - Observatoire des Sciences de l'Univers - Université de Brest (UBO) - Institut national des sciences de l'Univers (INSU - CNRS) Environnement, Géo-ingénierie et Développement (EGID) Department of Environmental, Geographic, and Geological Sciences ; Lehman College

Éditeur(s) : HAL CCSD AGU and the Geochemical Society
Résumé : International audience
Continental rifts and passive continental margins show fundamental along-axis segmentation patterns that have been attributed to one or a number of different processes: extensional fault geometry, variable stretching along strike, preexisting lithospheric compositional and structural heterogeneities, oblique rifting, and the presence or absence of eruptive volcanic centers. The length and width scales of the rift stage fault-bounded basin systems change during the late evolution of the new plate boundary, and the role of magmatism may increase as rifting progresses to continental rupture. Along obliquely spreading ridges, first-order mid-ocean ridge geometries originate during the synrift stage, indicating an intimate relationship between magma production and transform fault spacing and location. The Gulf of Aden rift is a young ocean basin in which the earliest synrift to breakup structures are well exposed onshore and covered by thin sediment layers offshore. This obliquely spreading rift is considered magma-poor and has several large-offset transforms that originated during late stage rifting and control the first-order axial segmentation of the spreading ridge. Widely spaced geophysical transects of passive margins that produce only isolated 2-D images of crust and uppermost mantle structure are inadequate for evaluation of competing rift evolution models. Using closely spaced new geophysical and geological observations from the Gulf of Aden we show that rift sectors between transforms have a large internal variability over short distances (∼10 km): the ocean-continent transition (OCT) evolves from a narrow magmatic transition to wider zones where continental mantle is probably exhumed. We suggest that this small-scale variability may be explained (1) by the distribution of volcanism and (2) by the along-strike differences in time-averaged extension rate of the oblique rift system. The volcanism may be associated with (1) the long-offset Alula-Fartak Fracture Zone, which may enhance magma production on its younger side, or (2) channeled flow from the Afar plume material along the newly formed OCT and the spreading ridge. Oblique extension and/or hot spot interactions may thereby have a significant control on the styles of rifting and continental breakup and on the evolution of many magma-poor margins.
ISSN: 1525-2027

hal-00504866
https://hal.archives-ouvertes.fr/hal-00504866
https://hal.archives-ouvertes.fr/hal-00504866/document
https://hal.archives-ouvertes.fr/hal-00504866/file/G3-Leroy_al-2010.pdf
DOI : 10.1029/2009GC002963

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Rapport présenté à l'Assemblée Générale des actionnaires du 17 aout 1943 - Usine du François
Auteur(s) : Usine du François
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Rapport présenté à l'Assemblée Générale des actionnaires du lundi 24 mai 1954 - Usine du François
Auteur(s) : Usine du François
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