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| Klingelhofer, Frauke; Geli, Louis; Matias, Luis; Steinsland, N; Mohr, J. |
| A series of eight high-resolution seismic refraction profiles from the ultra-slow spreading (16 mm yr(-1) full spreading rate) Mohns Ridge in the Norwegian-Greenland Sea has been treated with modern inversion methods. The profiles were shot parallel to the ridge at an off-axis distance of 0-135 km corresponding to crustal ages of 0-22 Ma. The resulting models are constrained by synthetic seismograms and gravity modelling.The crustal thickness in all profiles is well below the global average for typical oceanic crust, and shows a high variability with a mean thickness of 4.0 +/- 0.5 km. This is mainly due to a very thin and variable lower crustal layer (Layer 3). Generally, the crust is thicker beneath basement highs and thinner beneath basins, implying... |
| Tipo: Text |
Palavras-chave: Seismic refraction; Oceanic crust; Mohns Ridge; Mantle. |
| Ano: 2000 |
URL: https://archimer.ifremer.fr/doc/2000/publication-681.pdf |
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| Jaffal, Mohammed; Klingelhoefer, Frauke; Matias, Luis; Teixeira, Fernando; Amrhar, Mostafa. |
| During the SISMAR cruise (spring 2001), new deep seismic data were acquired on the Atlantic Moroccan margin. The purpose of the present work is to analyse and to interpret a part of the data consisting of four wide-angle seismic profiles (4, 5, 8 and 10) recorded offshore El Jadida. Lines 4 and 5, perpendicular to the margin, show a crustal thickness of 35 km under the western Moroccan Meseta which thins progressively seaward where it reaches a minimum thickness of 10 km. The calculated velocity models show that this crust consists of two crustal layers overlain by a sedimentary cover corresponding to the post-Paleozoic sediments, characterised by a low velocity. The detailed shallow structure is obtained primarily from multichannel seismic data. Half... |
| Tipo: Text |
Palavras-chave: Morocco; Passive margin; Gravity; OBS; Velocity model; Deep seismic. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6588.pdf |
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| Klingelhoefer, Frauke; Biari, Youssef; Sahabi, Mohamed; Aslanian, Daniel; Schnabel, Michael; Matias, Luis; Benabdellouahed, Massinissa; Funck, Thomas; Gutscher, Marc-andre; Reichert, Christian; Austin, James A.. |
| Deep seismic data represent a key to understand the geometry and mechanism of continental rifting. The passive continental margin of NW-Africa is one of the oldest on earth, formed during the Upper Triassic–Lower Liassic rifting of the central Atlantic Ocean over 200 Ma. We present new and existing wide-angle and reflection seismic data from four study regions along the margin located in the south offshore DAKHLA, on the central continental margin offshore Safi, in the northern Moroccan salt basin, and in the Gulf of Cadiz. The thickness of unthinned continental crust decreases from 36 km in the North to about 27 km in the South. Crustal thinning takes place over a region of 150 km in the north and only 70 km in the south. The North Moroccan Basin is... |
| Tipo: Text |
Palavras-chave: Moroccan continental margin; Wide-angle seismic; Passive margins; Deep structure; Plate reconstruction. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00316/42685/42058.pdf |
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| Moulin, Maryline; Aslanian, Daniel; Olivet, Jean-louis; Contrucci, Isabelle; Matias, Luis; Geli, Louis; Klingelhoefer, Frauke; Nouze, Herve; Rehault, Jean Pierre; Unternehr, Patrick. |
| Deep penetration multichannel reflection and Ocean Bottom Seismometer wide-angle seismic data from the CongoAngola margin were collected in 2000 during the ZaïAngo cruise. These data help constrain the deep structure of the continental margin, the geometry of the pre-salt sediment layers and the geometry of the Aptian salt layer. Dating the deposition of the salt relative to the chronology of the margin formation is an issue of fundamental importance for reconstructing the evolution of the margin and for the understanding of the crustal thinning processes. The data show that the crust thins abruptly, from a 3040 km thickness to less than 10 km, over a lateral distance of less than 50 km. The transitional domain is a 180-km-wide basin. The pre-salt sediment... |
| Tipo: Text |
Palavras-chave: Deep seismic reflection and refraction; Sub salt imaging; Transitional domain; Crustal structure; Non volcanic passive continental margin. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/2005/publication-349.pdf |
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| Hensen, Christian; Duarte, Joao C.; Vannucchi, Paola; Mazzini, Adriano; Lever, Mark A.; Terrinha, Pedro; Géli, Louis; Henry, Pierre; Villinger, Heinrich; Morgan, Jason; Schmidt, Mark; Gutscher, Marc-andre; Bartolome, Rafael; Tomonaga, Yama; Polonia, Alina; Gràcia, Eulàlia; Tinivella, Umberta; Lupi, Matteo; Çağatay, M. Namık; Elvert, Marcus; Sakellariou, Dimitris; Matias, Luis; Kipfer, Rolf; Karageorgis, Aristomenis P.; Ruffine, Livio; Liebetrau, Volker; Pierre, Catherine; Schmidt, Christopher; Batista, Luis; Gasperini, Luca; Burwicz, Ewa; Neres, Marta; Nuzzo, Marianne. |
| Marine transform faults and associated fracture zones (MTFFZs) cover vast stretches of the ocean floor, where they play a key role in plate tectonics, accommodating the lateral movement of tectonic plates and allowing connections between ridges and trenches. Together with the continental counterparts of MTFFZs, these structures also pose a risk to human societies as they can generate high magnitude earthquakes and trigger tsunamis. Historical examples are the Sumatra-Wharton Basin Earthquake in 2012 (M8.6) and the Atlantic Gloria Fault Earthquake in 1941 (M8.4). Earthquakes at MTFFZs furthermore open and sustain pathways for fluid flow triggering reactions with the host rocks that may permanently change the rheological properties of the oceanic... |
| Tipo: Text |
Palavras-chave: Transform faults; Fractures zones; Coupling of seismicity and fluid flow; Microbial life; Heat flow; Fluid geochemistry; Seafloor observation systems; Seismic precursors. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00489/60085/63422.pdf |
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| Matias, Luis; Olivet, Jean-louis; Aslanian, Daniel; Fidalgo, Luis. |
| PLACA was developed as a general purpose computer program for the earth scientist that has to manipulate the rigid plate tectonics theory, from the representation of plate reconstructions to the determination of best-fit poles using magnetic anomalies, fracture zones or volcanic alignments. In the "forward" mode PLACA has the features of most available demonstration software plus the ability of simulating mid-oceanic ridges (MOR) as dynamic segments that move with a fraction of the relative motion between two plates. The movement can be illustrated by the generation of flow lines, plate trajectories and/or pseudo-magnetic anomalies on the ocean floor. The evolution of simple triple junctions of the R-R-R type can also be studied. In the "modifying" mode,... |
| Tipo: Text |
Palavras-chave: Precision; Confidence region; Fortran; Plate tectonics; Tectonophysics. |
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/2005/publication-788.pdf |
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