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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... |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00678/79004/81397.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... |
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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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| Lepretre, Angelique; Klingelhoefer, Frauke; Graindorge, David; Schnurle, Philippe; Beslier, M. O.; Yelles, K.; Deverchere, Jacques; Bracene, R.. |
| The origin of the Algerian margin remains one of the key questions still discussed in the Western Mediterranean sea, due to the imprecise nature and kinematics of the associated basin during the Neogene. For the first time, the deep structure of the Maghrebian margin was explored during the SPIRAL seismic survey. In this work, we present a N-S transect off Tipaza (west of Algiers), a place where the margin broadens due to a topographic high (Khayr-al-Din Bank). New deep penetration seismic profiles allow us to image the sedimentary sequence in the Algerian basin and the crustal structure at the continent-ocean boundary. Modeling of the wide-angle data shows thinning of the basement, from more than 15km in the continental upper margin to only 5–6km of... |
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Palavras-chave: Algerian margin; Crustal structure; Wide-angle seismic data; Multiphased tectonic evolution; Western Mediterranean back-arc basins; Contractional reactivation. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00152/26333/24412.pdf |
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| Collot, Jean-julien; Sanclemente, Eddy; Nocquet, Jean-mathieu; Lepretre, Angelique; Ribodetti, Alessandra; Jarrin, Paul; Chlieh, Mohamed; Graindorge, David; Charvis, Philippe. |
| Whether subducted oceanic reliefs such as seamounts promote seismic rupture or aseismic slip remains controversial. Here we use swath bathymetry, prestack depth-migrated multichannel seismic reflection lines, and wide-angle seismic data collected across the central Ecuador subduction segment to reveal a broad similar to 55kmx50km, similar to 1.5-2.0km high, low height-to-width ratio, multipeaked, sediment-bare, shallow subducted oceanic relief. Owing to La Plata Island and the coastline being located, respectively, similar to 35km and similar to 50-60km from the trench, GPS measurements allow us to demonstrate that the subducted oceanic relief spatially correlates to a shallow, similar to 80kmx55km locked interplate asperity within a dominantly creeping... |
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Palavras-chave: Seamount subduction; Interseismic coupling; Seismic imaging; Slow slip event; Megathrust earthquake. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00638/75038/75652.pdf |
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