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Registros recuperados: 6
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The "lost Inca Plateau": cause of flat subduction beneath Peru? ArchiMer
Gutscher, Marc-andre; Olivet, Jean-louis; Aslanian, Daniel; Eissen, Jp; Maury, Rene.
Since flat subduction of the Nazca Plate beneath Peru was first recognized in the 1970s and 1980s a satisfactory explanation has eluded researchers. We present evidence that a lost oceanic plateau (Inca Plateau) has subducted beneath northern Peru and propose that the combined buoyancy of Inca Plateau and Nazca Ridge in southern Peru supports a 1500 km long segment of the downgoing slab and shuts off arc volcanism. This conclusion is based on an analysis of the seismicity of the subducting Nazca Plate, the structure and geochemistry of the Marquesas Plateau as well as tectonic reconstructions of the Pacific¿Farallon spreading center 34 to 43 Ma. These restore three sub¿parallel Pacific oceanic plateaus; the Austral, Tuamotu and Marquesas, to two Farallon...
Tipo: Text Palavras-chave: Nazca Plate; Subduction; Nazca Ridge; Peru; Reconstruction.
Ano: 1999 URL: http://archimer.ifremer.fr/doc/1999/publication-360.pdf
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Mantle exhumation at magma-poor passive continental margins. Part I. 3D architecture and metasomatic evolution of a fossil exhumed mantle domain (Urdach Iherzolite, north-western Pyrenees, France) ArchiMer
Lagabrielle, Yves; Asti, Riccardo; Fourcade, Serge; Corre, Benjamin; Poujol, Marc; Uzel, Jessica; Labaume, Pierre; Clerc, Camille; Lafay, Romain; Picazo, Suzanne; Maury, Rene.
In two companion papers, we report the detailed geological and mineralogical study of two emblematic serpentinized ultramafic bodies of the western North Pyrenean Zone (NPZ), the Urdach massif (this paper) and the Saraille massif (paper 2). The peridotites have been exhumed to lower crustal levels during the Cretaceous rifting period in the future NPZ. They are associated with Mesozoic pre-rift metamorphic sediments and small units of thinned Paleozoic basement that were deformed during the mantle exhumation event. Based on detailed geological cross-sections and microprobe mineralogical analyses, we describe the lithology of the two major extensional fault zones that accommodated: (i) the progressive exhumation of the lherzolites along the Cretaceous basin...
Tipo: Text Palavras-chave: North Pyrenean Zone; Urdach; Mantle exhumation; Fluid-rock interactions; Listvenites; Greenschist facies; Detachment faults; Late Cretaceous.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00637/74920/76106.pdf
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Young rift kinematics in the Tadjoura rift, western Gulf of Aden, Republic of Djibouti ArchiMer
Daoud, Mohamed A.; Le Gall, Bernard; Maury, Rene; Rolet, Joel; Huchon, Philippe; Guillou, Herve.
The Tadjoura rift forms the westernmost edge of the westerly propagating Sheba ridge, between Arabia and Somalia, as it enters into the Afar depression. From structural and remote sensing data sets, the Tadjoura rift is interpreted as an asymmetrical south facing half-graben, about 40 km wide, dominated by a large boundary fault zone to the north. It is partially filled up by the 1-3 Myr old Gulf Basalts which onlapped the older Somali Basalts along its shallower southern flexural margin. The major and trace element analysis of 78 young onshore lavas allows us to distinguish and map four distinct basaltic types, namely the Gulf, Somali, Goumarre, and Hayyabley Basalts. These results, together with radiometric age data, lead us to propose a revised...
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Ano: 2011 URL: http://archimer.ifremer.fr/doc/00200/31103/29502.pdf
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A low delta7 Li lower crustal component: Evidence from an alkalic intraplate volcanic series (Chaine des Puys, French Massif Central) ArchiMer
Hamelin, Cedric; Seitz, Hans-michael; Barrat, Jean-alix; Dosso, Laure; Maury, Rene; Chaussidon, Marc.
The intraplate volcanic suite of the Chaine des Puys (French Massif Central) shows a complete petrologic range, from alkali basalts to trachytes. The significant variations of trace elements and radiogenic isotopes along the series strongly support the occurrence of crustal assimilation associated with fractional crystallization (AFC). The least contaminated basalts are clearly related to a HIMU-type reservoir (Pb-206/Pb-204>19.6; Sr-87/Sr-86<0.7037; epsilon(Nd)>+4). The behavior of radiogenic isotopes suggests that the most likely crustal contaminants are meta-sediments located in the lower crust. The Li isotopic compositions of the lavas range from high delta Li-7 (> + 7 parts per thousand) in basalts to lighter values in more evolved lavas...
Tipo: Text Palavras-chave: Trachytes Basalts HIMU Assimilation and fractional crystallization (AFC) Lower crust Li; Sr; Nd and Pb isotopes.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6853.pdf
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How wide is the seismogenic zone of the Lesser Antilles forearc? ArchiMer
Gutscher, Marc-andre; Westbrook, Graham; Marcaillou, Boris; Graindorge, David; Gailler, Audrey; Pichot, Thibaud; Maury, Rene.
The Lesser Antilles subduction zone has produced no recent strong thrust earthquakes, making it difficult to quantify the seismic hazard from such events. The Lesser Antilles arc has a low subduction rate and an accretionary wedge that is very wide at its southern end. To investigate the effect of the wedge on seismogenesis, numerical models of forearc thermal structure were constructed along six transects perpendicular to the arc in order to determine the thermally predicted width of the seismogenic zone. The geometry of each section is constrained by published seismic profiles and crustal models derived from gravity and seismic data and by earthquake hypocenters at depth. A major constraint on the deep part of the model is that mantle temperature beneath...
Tipo: Text Palavras-chave: Zone sismogène; Séisme chevauchant; Modélisation thermique; Prisme d’accrétion; Petites Antilles; Seismogenic zone; Thrust earthquake; Thermal modeling; Accretionary wedge; Lesser Antilles.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00140/25140/29432.pdf
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Unusual seismic activity in 2011 and 2013 at the submarine volcano Rocard, Society hot spot (French Polynesia) ArchiMer
Talandier, Jacques; Hyvernaud, Olivier; Maury, Rene.
We analyze two seismic events that occurred on 27 May 2011 and 29 April 2013 at the Rocard submarine volcano which overlies the Society hot spot. The Polynesian Seismic Network recorded for the first time unusual associated short-and long-period signals, with perfectly monochromatic (0.0589 Hz) Rayleigh wave trains of long period and duration. None of the numerous observations of long-period (10-30 s) signals previously associated with volcanic activity in Japan, Italy, Mexico, Indonesia, Antarctica, and the Hawaiian Islands have the characteristics we observed at Rocard. We propose a tentative model for these unusual and rather enigmatic signals, in which the movement of lava excited the resonance of a shallow open conduit under a high hydrostatic...
Tipo: Text
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00639/75083/75614.pdf
Registros recuperados: 6
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