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Registros recuperados: 6
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High-resolution seismic imaging in deep sea from a joint deep-towed/OBH reflection experiment: application to a Mass Transport Complex offshore Nigeria ArchiMer
Ker, Stephan; Marsset, Bruno; Garziglia, Sebastien; Le Gonidec, Y.; Gibert, D.; Voisset, Michel; Adamy, J..
P>We assess the feasibility of high-resolution seismic depth imaging in deep water based on a new geophysical approach involving the joint use of a deep-towed seismic device (SYSIF) and ocean bottom hydrophones (OBHs). Source signature measurement enables signature deconvolution to be used to improve the vertical resolution and signal-to-noise ratio. The source signature was also used to precisely determine direct traveltimes that were inverted to relocate source and receiver positions. The very high accuracy of the positioning that was obtained enabled depth imaging and a stack of the OBH data to be performed. The determination of the P-wave velocity distribution was realized by the adaptation of an iterative focusing approach to the specific...
Tipo: Text Palavras-chave: Controlled source seismology; Seismic tomography; Acoustic properties; Submarine landslides; Atlantic Ocean.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00044/15510/12959.pdf
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Imaging proto-oceanic crust off the Brazilian Continental Margin ArchiMer
Klingelhoefer, Frauke; Evain, Mikael; Afilhado, A.; Rigoti, Caesar; Loureiro, Afonso; Alves, D.; Lepretre, Angelique; Moulin, Maryline; Schnurle, Philippe; Benabdellouahed, Massinissa; Baltzer, Agnes; Rabineau, Marina; Feld, Aurelie; Viana, A.; Aslanian, Daniel.
During the Sanba (Santos basin seismic transect) experiment in 2010–2011, a 380-km-long combined wide-angle and reflection seismic profile has been acquired using 30 ocean-bottom seismometers, a 4.5 km seismic streamer and a 8900 in.3 airgun array. The Sanba 3 profile crosses the southern flank of the Sao Paulo Plateau, the Sao Paulo Ridge and the easternmost Santos Basin in an east–west direction. Its eastern end is located on undisturbed oceanic crust. Tomographic and forward modelling of the wide-angle seismic data reveals that the sedimentary thickness is variable with only 1–2 km on top of the ridge and thickening to 4–5 km in the basin. Crustal thickness at the ridge is about 18 km and the relative layer thickness and velocity gradients indicate a...
Tipo: Text Palavras-chave: Controlled source seismology; Seismic tomography; Mid-ocean ridge processes; Continental margins: divergent; Continental tectonics: extensional; Crustal structure; South America.
Ano: 2015 URL: http://archimer.ifremer.fr/doc/00242/35296/33826.pdf
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Shallow subsurface morphotectonics of the NW Sumatra subduction system using an integrated seismic imaging technique ArchiMer
Ghosal, Dibakar; Singh, S. C.; Martin, J..
In subduction zones, shallow subsurface structures are the manifestation of the plate interactions at depth. However, significant water depths, rough bathymetry and presence of heavily deformed accretionary wedge materials hamper imaging of the near-surface features to a great extent using conventional imaging techniques. In this study, we show results using an integrated processing technique to a multichannel seismic data set acquired in 2006 from the northwestern offshore Sumatra. We start with first downward continuing the 12-km-long surface streamer data to the seafloor, followed by a high-resolution traveltime tomography of refracted phases to determine a detailed velocity-depth model of subsurface, which in turns, is used for pre-stack depth...
Tipo: Text Palavras-chave: Controlled source seismology; Seismic tomography; Subduction zone processes; Continental margins: convergent; Folds and folding.
Ano: 2014 URL: https://archimer.ifremer.fr/doc/00290/40094/39185.pdf
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Structure across the northeastern margin of Flemish Cap, offshore Newfoundland from Erable multichannel seismic reflection profiles: evidence for a transtensional rifting environment ArchiMer
Welford, J. Kim; Hall, Jeremy; Sibuet, Jean-claude; Srivastava, Shiri P..
P>We present the results from processing and interpreting nine multichannel seismic reflection lines collected during the 1992 Erable experiment over the northeastern margin of Flemish Cap offshore Newfoundland. These lines, combined into five cross-sections, provide increased seismic coverage over this lightly probed section of the margin and reveal tectonically significant along-strike variations in the degree and compartmentalization of crustal thinning. Similar to the southeastern margins of Flemish Cap and the Grand Banks, a transitional zone of exhumed serpentinized mantle is interpreted between thinned continental and oceanic crust. The 25 km wide transitional zone bears similarities to the 120 km wide transitional zone interpreted as exhumed...
Tipo: Text Palavras-chave: Controlled source seismology; Continental margins: divergent; Continental tectonics: extensional; Submarine tectonics and volcanism; Crustal structure; Atlantic Ocean.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00017/12776/11313.pdf
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Structure and rifting evolution of the northern Newfoundland Basin from Erable multichannel seismic reflection profiles across the southeastern margin of Flemish Cap ArchiMer
Welford, J. K.; Smith, J. A.; Hall, J.; Deemer, S.; Srivastava, S. P.; Sibuet, Jean-claude.
We present the results from processing and interpreting five lines from the 1992 Erable multichannel seismic reflection experiment extending from the southeastern margin of Flemish Cap into the northern Newfoundland Basin. These profiles reveal significant along strike variations in the rifting styles experienced by Flemish Cap. In the southwest, a 100-km-wide transition zone is identified between thinned continental crust and thin oceanic crust. Similar to the conjugate Galicia Bank and Iberian margins, this transition zone contains a section of deep basement adjacent to a series of shallower ridges and is interpreted as exhumed serpentinized mantle. Along strike towards the northeast, this transition zone pinches out completely within 100 km and is...
Tipo: Text Palavras-chave: Controlled source seismology; Submarine tectonics and volcanism; Continental margins: divergent; Continental tectonics: extensional; Crustal structure; Atlantic Ocean.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00001/11202/7876.pdf
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The crustal structure of the north-eastern Gulf of Aden continental margin: insights from wide-angle seismic data ArchiMer
Watremez, Louise; Leroy, Sylvie; Rouzo, Stephane; D'Acremont, E.; Unternehr, P.; Ebinger, C.; Lucazeau, F.; Al-lazki, A..
P>The wide-angle seismic (WAS) and gravity data of the Encens survey allow us to determine the deep crustal structure of the north-eastern Gulf of Aden non-volcanic passive margin. The Gulf of Aden is a young oceanic basin that began to open at least 17.6 Ma ago. Its current geometry shows first- and second-order segmentation: our study focusses on the Ashawq-Salalah second-order segment, between Alula-Fartak and Socotra-Hadbeen fracture zones. Modelling of the WAS and gravity data (three profiles across and three along the margin) gives insights into the first- and second-order structures. (1) Continental thinning is abrupt (15-20 km thinning across 50-100 km distance). It is accommodated by several tilted blocks. (2) The ocean-continent transition...
Tipo: Text Palavras-chave: Controlled source seismology; Continental margins: divergent; Crustal structure; Indian Ocean.
Ano: 2011 URL: http://archimer.ifremer.fr/doc/00200/31102/29507.pdf
Registros recuperados: 6
Primeira ... 1 ... Última
 

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