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| Registros recuperados: 13 | |
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| Champilou, Jean-baptiste; Baltzer, Agnes; Murat, Anne; Reynaud, Marine; Maillet, Grégoire M.; Nardelli, Maria Pia; Metzger, Édouard. |
| In the shallow waters of the Bay of Concarneau (South Brittany, France), previous studies reported a dense settlement of the species Haploops (tube-dwelling bioengineer amphipod) that perfectly overlaps a field of pockmarks. A possible mechanistic link may therefore exist between the Haploops colonies and the shallow pockmarks. To test this hypothesis, interferometry sonar and sub-bottom profiler chirp data were acquired in two new areas located in the marine estuary of the Loire River, “La Lambarde” and “Le Croisic”. The new sites share the same sedimentary and geological characteristics as those found in the Bay of Concarneau. The three sites are similarly located in shallow and muddy environments above a faulted Middle Eocene formation that is incised... |
| Tipo: Text |
Palavras-chave: Shallow waters; South Brittany (France); Geophysics; Pockmarks; Haploops. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00502/61324/64896.pdf |
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| Baltzer, Agnes; Reynaud, Marine; Ehrhold, Axel; Fournier, Jerome; Cordier, Celine; Clouet, Helene. |
| About a decade ago, a large field of pockmarks, covering an overall area of 36 km(2) was discovered in water depths of < 30m in the central part of the Bay of Concarneau (Southern Brittany, France). This field, composed of features from 5 m to 35 m in diameter and < 1 m in depth, is characterized by unusual high densities of pockmarks, up to 5840 per square kilometre. Geophysical data correlated with sedimentary samples acquired in 2005 and 2009 show that pockmarks and their immediate surroundings are associated with dense tubes benches cover, built by a filter-feeding amphipod: Haploops nirae, forming original benthic communities. Two complementary surveys were carried out in April 2011 (Pock and Ploops) and April 2014 (Pock and Tide), on the... |
| Tipo: Text |
Palavras-chave: Géophysique; Marée; Failles; Gaz; Geophysics; Pockmarks; Tide; Turbidity; Gas; Chimneys pipes; Concarneau. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00410/52107/52938.pdf |
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| Benabdellouahed, Massinissa; Baltzer, Agnes; Rabineau, Marina; Aslanian, Daniel; Sahabi, Mohamed; Germond, Fabien; Loubrieu, Benoit; Biari, Youssef. |
| This study explores a portion of the West African margin at the junction between two well- known segments offshore Dakhla and offshore Mauritania with destructional architecture characterized by giant slides. In between these two segments, the Dakhla segment has historically been described as a constructional section. During an oceanographic Dakhla cruise (2002), high resolution seismic data, swath bathymetry and imagery were acquired around latitude 23° N, offshore Dakhla,. This new data set reveals the existence of varied and complex morphologies on the continental slope, interpreted as a "shallot-shaped" canyon, seafloor depressions or pockmarks, ridges and scarps. These morphologies are interpreted as clues of sedimentary transfers and rupture... |
| Tipo: Text |
Palavras-chave: African margin; Bathymetry; Seismic interpretation; Pockmarks; Ridges; Scarps.. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00286/39736/38214.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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| Launeau, Patrick; Giraud, Manuel; Robin, Marc; Baltzer, Agnes. |
| In shoreline monitoring, only topo-bathymetric light detection and ranging (LiDAR) can map large corridors from aerial dunes to sandbanks in shallow water. Increasing turbidity masking the formation of 532 nm laser beam echoes on the sea bed makes this challenging. Full-waveform recording all the laser beam damping functions, a turbid water column can be seen as an accumulation of layers forming a single continuum and a distinction can be made between signals ending at the bottom down to a depth of 10 m. In practice full-waveforms are converted by laser beam tracing an image cube with a grid of 1-m-wide pixels and a 0.15 m range resolution storing the mean intensities returned along incident angle. The first derivative of a wide Gaussian filter serves to... |
| Tipo: Text |
Palavras-chave: Full-waveform; Airborne LiDAR; Bathymetry; Shoreline monitoring; Turbidity. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00476/58745/61270.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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| Smeaton, Craig; Austin, William E. N.; Davies, Althea L.; Baltzer, Agnes; Abell, Richard E.; Howe, John A.. |
| Quantifying marine sedimentary carbon stocks is key to improving our understanding of long-term storage of carbon in the coastal ocean and to further constraining the global carbon cycle. Here we present a methodological approach which combines seismic geophysics and geochemical measurements to quantitatively estimate the total stock of carbon held within marine sediment. Through the application of this methodology to Loch Sunart, a fjord on the west coast of Scotland, we have generated the first full sedimentary carbon inventory for a fjordic system. The sediments of Loch Sunart hold 26.9 ± 0.5 Mt of carbon split between 11.5 ± 0.2 and 15.0 ± 0.4 Mt of organic and inorganic carbon respectively. These new quantitative estimates of carbon stored in coastal... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00355/46591/46404.pdf |
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| Benabdellouahed, Massinissa; Klingelhoefer, Frauke; Gutscher, M. -a.; Rabineau, Marina; Biari, Youssef; Hafid, M.; Duarte, J. C.; Schnabel, M.; Baltzer, Agnes; Pedoja, K.; Le Roy, P.; Reichert, C.; Sahabi, M.. |
| Re-examination of marine geophysical data from the continental margin of West Morocco reveals a broad zone characterized by deformation, active faults and updoming offshore the High Atlas (Morocco margin), situated next to the Tafelney Plateau. Both seismic reflection and swath-bathymetric data, acquired during Mirror marine geophysical survey in 2011, indicate recent uplift of the margin including uplift of the basement. This deformation, which we propose to name the Atlantic Atlas tectonic arch, is interpreted to result largely through uplift of the basement, which originated during the Central Atlantic rifting stage - or even during phases of Hercynian deformation. This has produced a large number of closely spaced normal and reverse faults, “piano key... |
| Tipo: Text |
Palavras-chave: Atlas Mountain belt; Tectonic arch; Moroccan passive margin; Submerged terraces; Uplift. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00378/48975/49382.pdf |
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| Michel, Guillaume; Dupre, Stephanie; Baltzer, Agnes; Ehrhold, Axel; Imbert, Patrice; Pitel, Mathilde; Loubrieu, Benoit; Scalabrin, Carla; Lazure, Pascal; Marie, Louis; Geldof, Jean-baptiste; Deville, Eric. |
| Inactive and mostly elongated pockmarks of 100–200 m in dimension were recently discovered on the South Aquitaine Margin continental slope. They are distributed at water depths greater than 350 m in both interfluve and sediment-wave areas, and are strongly controlled by the sedimentary morphology and architecture. Water column and seafloor backscatter and sub-bottom profiler data do not exhibit present-day or past gas evidence, e.g., massive and continuous gas releases at the seabed and fossil methane-derived authigenic carbonates. It is thus proposed that the pockmarks originated from a shallow source and result from relatively recent and short-duration gas or water expulsion events. Former near-bottom currents may have contributed to the elongation of... |
| Tipo: Text |
Palavras-chave: Pockmark; Fluid; Seabed morphology; Aquitaine slope; GIS; Currents. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00413/52491/53279.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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| 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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| Registros recuperados: 13 | |
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