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| Registros recuperados: 11 | |
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| Tsang-hin-sun, Eve; Evain, Mikael; Julia, J; Lamarque, G; Schnurle, Philippe. |
| This study investigates the seismic structure and anisotropy in the crust beneath Madagascar and south-eastern Africa, using receiver functions. The understanding of seismic anisotropy is essential for imaging past and present deformation in the lithosphere-asthenosphere system. In the upper mantle, seismic anisotropy mainly results from the orientation of olivine, which deforms under tectonic (fossil anisotropy) or flow processes (in the asthenosphere). In the crust, the crystallographic alignment of amphiboles, feldspars(plagioclase) or micas or the alignment of heterogeneities such as fractures, add to a complex geometry, which results in challenges to understanding the Earth's shallow structure. The decomposition of receiver functions into back-azimuth... |
| Tipo: Text |
Palavras-chave: Crustal seismic anisotropy; Inherited structural heterogeneities; Crustal stress; Receiver function harmonics; Madagascar; Africa; EARS. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00686/79843/82668.pdf |
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| Evain, Mikael; Schnurle, Philippe; Lepretre, Angelique; Verrier, Fanny; Watremez, Louise; Thompson, Joseph Offei; De Clarens, Philippe; Aslanian, Daniel; Moulin, Maryline. |
| Deep seismic acquisitions and a new kinematic study recently highlighted the presence of continental crust in both the southern Mozambique's Coastal Plain (MCP) and further offshore in the North Natal Valley (NNV). Such findings falsify previous geodynamic scenarios based on the kinematic overlap between Antarctica and Africa plates, thus profoundly impacting our understanding East-Gondwana break-up. Using an updated position of Antarctica with respect to Africa this study reconsider the formation mechanism of East-African margins and most specifically of the Limpopo margin (LM). Coincident wide-angle and multi-channel seismic data acquired within the PAMELA project are processed to image the sedimentary and deep crustal structure along a profile that runs... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00678/79004/81397.pdf |
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| Biari, Youssef; Klingelhoefer, Frauke; Sahabi, Mohamed; Aslanian, Daniel; Schnurle, Philippe; Berglar, K.; Moulin, Maryline; Mehdi, K.; Graindorge, D.; Evain, Mikael; Benabdellouahed, Massinissa; Reichert, C.. |
| The structure of the Moroccan and Nova Scotia conjugate rifted margins is of key importance for understanding the Mesozoic break-up and evolution of the northern central Atlantic Ocean basin. Seven combined multichannel reflection (MCS) and wide-angle seismic (OBS) data profiles were acquired along the Atlantic Moroccan margin between the latitudes of 31.5° and 33° N during the MIRROR seismic survey in 2011, in order to image the transition from continental to oceanic crust, to study the variation in crustal structure and to characterize the crust under the West African Coast Magnetic Anomaly (WACMA). The data were modeled using a forward modeling approach. The final models image crustal thinning from 36 km thickness below the continent to approximately 8... |
| Tipo: Text |
Palavras-chave: Moroccan continental margin; Wide-angle seismic modeling; Deep crustal structure; Ocean continent transition. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00273/38401/36726.pdf |
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| Evain, Mikael; Afilhado, A.; Rigoti, C.; Loureiro, Afonso; Alves, D.; Klingelhoefer, Frauke; Schnurle, Philippe; Feld, Aurelie; Fuck, R.; Soares, J.; De Lima, M. Vinicius; Corela, C.; Matias, L.; Benabdellouahed, Massinissa; Baltzer, Agnes; Rabineau, Marina; Viana, A.; Moulin, Maryline; Aslanian, Daniel. |
| The structure and nature of the crust underlying the Santos Basin-São Paulo Plateau System (SSPS), in the SE Brazilian margin, are discussed based on five wide-angle seismic profiles acquired during the Santos Basin (SanBa) experiment in 2011. Velocity models allow us to precisely divide the SSPS in six domains from unthinned continental crust (Domain CC) to normal oceanic crust (Domain OC). A seventh domain (Domain D), a triangular shape region in the SE of the SSPS, is discussed by Klingelhoefer et al. (2014). Beneath the continental shelf, a ~100 km wide necking zone (Domain N) is imaged where the continental crust thins abruptly from ~40 km to less than 15 km. Toward the ocean, most of the SSPS (Domains A and C) shows velocity ranges, velocity... |
| Tipo: Text |
Palavras-chave: Santos Basin; SAo Paulo Plateau; Crustal structure; Wide-angle seismic. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00276/38715/37232.pdf |
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| Paulatto, Michele; Laigle, Mireille; Galve, Audrey; Charvis, Philippe; Sapin, Martine; Bayrakci, Gaye; Evain, Mikael; Kopp, Heidrun. |
| Subducting slabs carry water into the mantle and are a major gateway in the global geochemical water cycle. Fluid transport and release can be constrained with seismological data. Here we use joint active-source/local-earthquake seismic tomography to derive unprecedented constraints on multi-stage fluid release from subducting slow-spread oceanic lithosphere. We image the low P-wave velocity crustal layer on the slab top and show that it disappears beneath 60–100 km depth, marking the depth of dehydration metamorphism and eclogitization. Clustering of seismicity at 120–160 km depth suggests that the slab’s mantle dehydrates beneath the volcanic arc, and may be the main source of fluids triggering arc magma generation. Lateral variations in seismic... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00392/50321/51004.pdf |
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| Moulin, Maryline; Aslanian, Daniel; Evain, Mikael; Leprêtre, Angelique; Schnurle, Philippe; Verrier, Fanny; Thompson, Joseph Offei; De Clarens, P.; Leroy, S.; Dias, N.; The Pamela‐moz35 Team,. |
| The Natal Valley, offshore Mozambique, is a key area for understanding the evolution of East Gondwana. Within the scope of the integrated multidisciplinary PAMELA project, we present new wide‐angle seismic data and interpretations, which considerably alter Geoscience paradigms. These data reveal the presence of a 30 km‐thick crust that we argue to be of continental nature. This falsifies all the most recent paleo‐reconstructions of the Gondwana. This 30 km‐thick continental crust 1000 m below sea level implies a complex history with probable intrusions of mantle‐derived melts in the lower crust, connected to several occurrences of magmatism, which seems to evidence the crucial role of the lower continental crust in passive margin genesis. |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00598/71055/69368.pdf |
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| Loureiro, Afonso; Schnurle, Philippe; Klingelhofer, F.; Afilhado, A.; Pinheiro, Joao Marcelo; Evain, Mikael; Gallais, Flora; Dias, N. A.; Rabineau, Marina; Baltzer, Agnes; Benabdellouahed, Massinissa; Soares, J.; Fuck, R.; Cupertino, J. A.; Viana, A.; Matias, L.; Moulin, Maryline; Aslanian, Daniel; Vinicius Aparecido Gomes De Lima, M.. |
| Twelve combined wide-angle refraction and coincident multi-channel seismic profiles were acquired in the Jequitinhonha-Camamu-Almada, Jacuípe, and Sergipe-Alagoas basins, NE Brazil, during the SALSA experiment in 2014. Profiles SL11 and SL12 image the Jequitinhonha basin, perpendicularly to the coast, with 15 and 11 four-channel ocean-bottom seismometers, respectively. Profile SL10 runs parallel to the coast, crossing profiles SL11 and SL12, imaging the proximal Jequitinhonha and Almada basins with 17 ocean-bottom seismometers. Forward modelling, combined with pre-stack depth migration to increase the horizontal resolution of the velocity models, indicates that sediment thickness varies between 3.3 km and 6.2 km in the distal basin. Crustal thickness at... |
| Tipo: Text |
Palavras-chave: NE Brazil; South Atlantic Ocean; Passive margins; Wide-angle refraction seismic; PSDM; Crustal structure; Cretaceous breakup; Lower continental crust. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00428/53928/55054.pdf |
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| 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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| Pinheiro, Joao Marcelo; Schnurle, Philippe; Evain, Mikael; Afilhado, A.; Gallais, Flora; Klingelhoefer, Frauke; Loureiro, Afonso; Fuck, R.; Soares, J.; Cupertino, J. A.; Viana, A.; Rabineau, Marina; Baltzer, Agnes; Benabdellouahed, Massinissa; Dias, N.; Moulin, Maryline; Aslanian, Daniel; Morvan, Laetitia; Maze, Jean-pierre; Pierre, Delphine; Pitel-roudaut, Mathilde; Rio, I; Alves, D.; Barros Junior, P.; Biari, Youssef; Corela, C.; Crozon, Jacques; Duarte, J. L.; Ducatel, Cecile; Falcao, C.; Fernagu, Philippe; Le Piver, David; Mokeddem, Zohra; Pelleau, Pascal; Rigoti, C.; Roest, Walter; Roudaut, Mickael. |
| The structure and nature of the crust underlying the Camamu-Almada-Jequitinhonha-Sergipe-Alagoas basins System, in the NE Brazilian margin, were investigated based on the interpretation of 12 wide-angle seismic profiles acquired during the SALSA (Sergipe ALagoas Seismic Acquisition) experiment in 2014. In this work, we present two 220-km-long NW-SE combined wide-angle and reflection seismic profiles, SL 01 and SL 02, that have been acquired using 15 ocean-bottom-seismometers along each profile, offshore the southern part of the Sergipe Alagoas Basin (SAB), north of the Vaza-Barris Transfer zone. The SL 02 has a 150-km long inland continuation with 20 land-seismic-stations until the Sergipano Fold Belt (SFB). Wide-angle seismic forward modeling allows us to... |
| Tipo: Text |
Palavras-chave: South Atlantic ocean; NE Brazil; Sergipe-Alagoas basin; Passive margins; Wide-angle refraction seismics; Crustal structure; Tectonic inheritance. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00461/57263/59315.pdf |
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| Registros recuperados: 11 | |
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