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Registros recuperados: 10
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Active faulting and deep crustal structure of the Eastern Sicily Margin ArchiMer
Dellong, David.
In the Ionian Sea (central Mediterranean) the slow convergence between Africa and Eurasia results in the formation of a narrow subduction zone. The nature of the crust of the subducting plate remains debated and could represent the last remnants of the Neo-Tethys ocean. The origin of the Ionian basin is also under discussion, especially concerning the rifting mechanisms as the Malta Escarpment could represent a remnant of this opening. This subduction retreats toward the south-east (motion occurring since the last 35 Ma) but is confined to the narrow Ionian basin. A major lateral slab tear fault is required to accommodate the slab rollback.This fault is thought to propagate along the eastern Sicily margin but its precise location remains controversial.This...
Tipo: Text Palavras-chave: Méditerranée; Ionien; Calabre; Géodynamique; Marge; Faille de déchirure lithosphérique; Sismicité; Sismique; Grand-angle; Bathymétrie; Gravimétrie; Modélisation; Mediterranean; Ionian; Calabria; Geodynamic; Subduction; Margin; STEP fault; Wide-angle seismic; Seismicity; Bathymetry; Gravity; Modelling.
Ano: 2018 URL: https://archimer.ifremer.fr/doc/00499/61026/64430.pdf
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Active tectonics of the Calabrian subduction revealed by new multi-beam bathymetric data and high-resolution seismic profiles in the Ionian Sea (Central Mediterranean) ArchiMer
Gutscher, Marc-andre; Kopp, Heidrun; Krastel, Sebastian; Bohrmann, Gerhard; Garlan, Thierry; Zaragosi, Sebastien; Klaucke, Ingo; Wintersteller, Paul; Loubrieu, Benoit; Le Faou, Yann; San Pedro, Laurine; Dominguez, Stephane; Rovere, Marzia; De Lepinay, Bernard Mercier; Ranero, Cesar; Sallares, Valenti.
The detailed morphology and internal structure of the Calabrian accretionary wedge and adjacent Eastern Sicily margin are imaged in unprecedented detail by a combined dataset of multi-beam bathymetry and high-resolution seismic profiles. The bathymetric data represent the results of 6 recent marine geophysical surveys since 2010 as well as a compilation of earlier surveys presented as a 2 arc-sec (60 m) grid. Several distinct morpho-tectonic provinces are identified including: the deeply incised Malta–Hyblean Escarpment, numerous submarine canyons, broad regions of relatively flat seafloor dominated by fields of sediment waves, the gently undulating anticlinal fold-and-thrust belts of the external Calabrian accretionary wedge and the adjacent portion of...
Tipo: Text Palavras-chave: Subduction; Active faults; Eurasia-Africa plate boundary; Bathymetry; Seismic profiles; Accretionary wedge.
Ano: 2017 URL: https://archimer.ifremer.fr/doc/00366/47685/47853.pdf
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Evolution Géodynamique du domaine Ouest-offshore de la Nouvelle-Calédonie et de ses extensions vers la Nouvelle-Zélande ArchiMer
Collot, Julien.
The southwest Pacific results from the fragmentation of Gondwanaland since the Cretaceous time. The purpose of the current PhD work is to deepen our understanding of the history of the New Caledonia and Fairway basins, located west of New Caledonia, in order to better constrain the geodynamical evolution of the SW Pacific from Cretaceous to Oligocene. The analysis of new geophysical data has led to distinguish 3 main phases of this fragmentation: 1 Mid Cretaceous formation of the Fairway-Aotea Basin in a continental intra-arc position. The formation of this basin reflects the initial stage of continental fragmentation of the Eastern Gondwana margin. The causes of this fragmentation are to be searched for in a major change of the dynamics of the...
Tipo: Text Palavras-chave: Subduction; Obduction; Norfolk; Lord Howe; Gondwana; Taranaki; New Caledonia; Fairway; Aotea; Magnetic; Gravity; Seismic; Subduction; Obduction; Norfolk; Lord Howe; Gondwana; Taranaki; Nouvelle Calédonie; Fairway; Aotea; Magnétisme; Gravimétrie; Sismique.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/these-6520.pdf
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Impact of lower plate structure on upper plate deformation at the NW Sumatran convergent margin from seafloor morphology ArchiMer
Graindorge, D; Klingelhoefer, Frauke; Sibuet, Jean-claude; Mcneill, L; Henstock, T; Dean, S; Gutscher, M; Dessa, J; Permana, H; Singh, S; Leau, H; White, N; Carton, H; Malod, Jacques-andre; Rangin, C; Aryawan, K; Chaubey, A; Chauhan, A; Galih, D; Greenroyd, C; Laesanpura, A; Prihantono, J; Royle, G; Shankar, U.
We present results from multibeam bathymetric data acquired during 2005 and 2006, in the region of maximum slip of the 26 Dec. 2004 earthquake (Mw 9.2). These data provide high-resolution images of seafloor morphology of the entire NW Sumatra forearc from the Sunda trench to the submarine volcanic arc just north of Sumatra. A slope gradient analysis of the combined dataset accurately highlights those portions of the seafloor shaped by active tectonic, depositional and/or erosional processes. The greatest slope gradients are located in the frontal 30 km of the forearc, at the toe of the accretionary wedge. This suggests that long-term deformation rates are highest here and that probably only minor amounts of slip are accommodated by other thrust faults...
Tipo: Text Palavras-chave: Sumatra; Tectonic; Seafloor morphology; Accretionary wedge; Subduction.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-5166.pdf
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Synthesis of the POMME physical data set: One year monitoring of the upper layer ArchiMer
Gaillard, Fabienne; Mercier, Herle; Kermabon, Catherine.
The Programme Ocean Multidisciplinaire Meso Echelle (POMME) experiment was designed to describe and quantify the role of mesoscale processes in the subduction of mode waters in the northeast Atlantic. During 1 year ( September 2000 - October 2001), in situ measurements were conducted over a 8 degrees square area centered on 18 degrees W, 42 degrees N. We present the synthesis of the physical data set collected during this experiment. To improve time and space coverages, these measurements are combined with satellite information from sea surface temperature and altimetry. Daily fields of temperature, salinity, and stream function are produced over a seasonal cycle with a simplified Kalman filter. We analyze the annual cycle of the upper layer. The 1 year...
Tipo: Text Palavras-chave: Upper ocean seasonal cycle; Mesoscale; Northeast Atlantic; Subduction; Mode water; Mixed layer.
Ano: 2005 URL: http://archimer.ifremer.fr/doc/2005/publication-455.pdf
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Tectonic expression of an active slab tear from high-resolution seismic and bathymetric data offshore Sicily (Ionian Sea) ArchiMer
Gutscher, Marc-andre; Dominguez, Stephane; Mercier De Lepinay, Bernard; Pinheiro, Luis; Gallais, Flora; Babonneau, Nathalie; Cattaneo, Antonio; Le Faou, Yann; Barreca, Giovanni; Micallef, Aaron; Rovere, Marzia.
Subduction of a narrow slab of oceanic lithosphere beneath a tightly curved orogenic arc requires the presence of at least one lithospheric scale tear fault. While the Calabrian subduction beneath southern Italy is considered to be the type example of this geodynamic setting, the geometry, kinematics and surface expression of the associated lateral, slab tear fault offshore eastern Sicily remain controversial. Results from a new marine geophysical survey conducted in the Ionian Sea, using high-resolution bathymetry and seismic profiling reveal active faulting at the seafloor within a 140 km long, two-branched fault system near Alfeo Seamount. The previously unidentified 60 km long NW trending North Alfeo Fault system shows primarily strike-slip kinematics...
Tipo: Text Palavras-chave: Slab tear; Subduction; Mediterranean; Bathymetry; Seismics; Active faults.
Ano: 2016 URL: https://archimer.ifremer.fr/doc/00318/42924/42421.pdf
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Temporal magma source changes at Gaua volcano, Vanuatu island arc ArchiMer
Beaumais, Aurelien; Bertrand, Herve; Chazot, Gilles; Dosso, Laure; Robin, Claude.
Gaua Island (also called Santa Maria), from the central part of the Vanuatu arc, consists of a large volcano marked by a caldera that hosts the active Mount Garet summit cone. In this paper, a geochemical study including Sr, Nd, Pb and Hf isotopic compositions of 25 lavas emitted since 1.8 Ma is presented, with a focus on the volcanic products that preceded (old volcanics, main cone and pyroclastic series) and followed (Mount Garet) the caldera forming event. All lavas show an island arc signature with enrichment in LILE and depletion in HFSE. Post-caldera lavas define a medium-K calc-alkaline trend, whereas lavas from the former main cone have high-K calc-alkaline compositions. Compared to the pre-caldera volcanic suite, the Mount Garet lavas have...
Tipo: Text Palavras-chave: Gaua; Vanuatu; Geochemistry; Isotopes; Subduction; Mantle source.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00319/43052/42557.pdf
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Temporal source evolution and crustal contamination at Lopevi Volcano, Vanuatu Island Arc ArchiMer
Beaumais, Aurelien; Chazot, Gilles; Dosso, Laure; Bertrand, Herve.
Here we present a new geochemical study of Lopevi volcano, one the most active volcanoes in the Vanuatu island arc. We focus on the temporally well-defined sequence of lava flows emitted since 1960, and for the first time, on pre-1960 volcanic products, including high-MgO basalts and felsic andesites, the most evolved lavas sampled so far on this island. This work reports the first Pb and Hf isotopic study of lavas from Lopevi island. These lavas display correlations between differentiation indexes such as SiO2 content and isotopic ratios. The felsic andesites extend the known correlations with both the least (Sr-Pb) and the most (Nd-Hf) radiogenic isotopic compositions on the island. Our results confirm that the rising magma interacted with the sub-arc...
Tipo: Text Palavras-chave: Lopevi; Vanuatu; Geochemistry; Isotopes; Subduction; Mantle source.
Ano: 2013 URL: http://archimer.ifremer.fr/doc/00167/27801/26223.pdf
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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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Thermal modeling of the SW Ryukyu forearc (Taiwan): Implications for the seismogenic zone and the age of the subducting Philippine Sea Plate (Huatung Basin) ArchiMer
Gutscher, M. -a.; Klingelhoefer, Frauke; Theunissen, T.; Spakman, W.; Berthet, T.; Wang, T. K.; Lee, C. -s..
Subduction mega-thrust earthquakes in the SW Ryukyu trench pose a seismic and tsunami hazard. One of the objectives of this study is to estimate the downdip width of the seismogenic zone using numerical modeling to determine the temperature distribution along the plate interface. However, this approach depends strongly on the thermal parameters of the subducting slab. While the Philippine Sea plate (PSP) subducting beneath the central and eastern Ryukyu arc is of Eocene age (35–50 Ma), its age west of the Gagua Ridge is uncertain, with proposed ages ranging from Lower Cretaceous (140 Ma) to Upper Eocene (35 Ma). Since the sparse available heat flow data are insufficient to resolve this debate, both end-member hypotheses are tested as input parameters. We...
Tipo: Text Palavras-chave: Subduction; Finite-element modeling; Forearc thermal structure; Seismogenic zone.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00324/43522/43054.pdf
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