Éditeur(s) : Gauthier-villars
Résumé : During the Kanaut cruise of the submersible Nautile and its mothership Le-Nadir (15 November-16 December 1992), one dive was devoted to the detailed study of a specific area of the neovolcanic ridge of the MAR around 29-degrees-06'N and 43-degrees-11'W. This study emphasizes the importance of the juxtaposition and the stacking of hundreds of small volcanoes in the construction of a neovolcanic ridge and confirms the general observation made from multibeam and side-scan sonar data. The very large magnetic anomaly associated with these massifs favours an extreme freshness.
Lors de la campagne Kanaut (15 novembre-16 décembre 1992) du Nautile et de son navire support Le-Nadir, une plongée a été consacrée B l'étude détaille d'un secteur de la ride néovalcanique de l'axe de la dorsale médio-Atlantique autour de 29"06" et 43"ll'W. Cette étude permet de souligner le rôle prépondérant que jouent les centaines de petits édifices volcaniques dans la construction de la ride néovolcanique, par leur juxtaposition et leur superposition. Ceci confirme et affine les observations faites B partir des données des sondeurs multifaisceaux et les sonars latéraux. La très forte anomalie magnétique associé B ces édifices penche en faveur de leur extrème fraicheur.
Comptes Rendus de l'Academie des Sciences Serie II (1251-8069) (Gauthier-villars), 1993-05 , Vol. 316 , N. 10 , P. 1415-1422

Droits : Académie des Sciences
http://archimer.ifremer.fr/doc/00183/29475/27887.pdf
http://archimer.ifremer.fr/doc/00183/29475/

Éditeur(s) : Springer
Résumé : Based on new multibeam bathymetric data, seismic-reflection profiles and side-scan sonar images, a great number of submarine failures of various types and sizes was identified along the northern margin of the Ligurian Basin and characterized with 3 distinct end-members concerning their location on the margin, sedimentary processes and possible triggering mechanisms. They include superficial landslides mainly located in the vicinity of the main mountain-supplied rivers and on the inner walls of canyons (typically smaller that 10(8) m(3) in volume: Type 1), deep scars 100-500 m high along the base of the continental slope (Type 2), and large-scale scars and Mass Transport Deposits (MTDs) affecting the upper part of the slope (Type 3 failures). The MTDs are located in different environmental contexts of the margin, including the deep Var Sedimentary Ridge (VSR) and the upper part of the continental slope in the Gulf of Genova (Finale Slide and Portofino Slide), with volumes of missing sediment reaching up to 1.5 x 10(9) m(3). High sedimentation rates related to hyperpycnal flows, faults and earthquake activity, together with sea-level fluctuations are the main factors invoked to explain the distribution and sizes of these different failure types.
Marine Geophysical Research (0025-3235) (Springer), 2011-03 , Vol. 32 , N. 1-2 , P. 225-243

Droits : Springer Science+Business Media B.V. 2011
http://archimer.ifremer.fr/doc/00043/15387/14028.pdf
DOI:10.1007/s11001-011-9123-3
http://archimer.ifremer.fr/doc/00043/15387/

Éditeur(s) : Society for Sedimentary Geology
Résumé : The Kramis deep-sea fan extends over 45 km at the base of the western Algerian continental slope between 2000 and 2550 m water depth and covers an area of approximately 1200 km2. The Kramis Fan was initiated after Messinian time, evolved during the Plio-Quaternary, and, is still active, as proved by submarine cable breaks during the 1954 Orléansville earthquake. The Kramis Fan is fed by two perpendicular canyons: the Kramis Canyon and the Khadra Canyon, merging in a single E–W-oriented channel confined at the foot of the slope. It is strongly asymmetric with a super-developed levee on the right-hand side of the channel, the Kramis Ridge. Based on recent multibeam, side-scan sonar, and sediment core data (Maradja, 2003 and 2005, Prisma, 2004, and Prisme, 2007 cruises), we describe the morphology and internal structure of the fan and particularly the sediment ridge, showing marked lateral changes in the sediment-wave morphology and their association with a series of large scours in the intermediate part of the ridge aligned in the continuity of the Khadra Canyon direction. Overall, the Kramis Ridge is formed by turbidity currents overspilling the ridge crest, which is 100 m above the channel floor, with two exceptions. In the distal part of the ridge the subdued ridge-crest height probably causes continuous overspill, testified by sediment waves migrating parallel to the channel. The scours occur in the intermediate part of the ridge where the ridge height is only 50–60 m; scours are interpreted as the result of cyclic steps due to flow stripping of currents provided by the intersection of the Khadra Canyon with the Kramis Canyon and Channel system. The scours probably postdate the main growth of the Kramis Ridge and induce the local erosion of the ridge, which could correspond to a new channel initiation cutting the ridge. The superposition or the interaction of flows with different directions is responsible of the amplification of the size of the sediment waves with erosional downside flanks and their transformation in scours. The Kramis Fan provides a clear example of flow interaction to explain the presence of large sediment waves and scours on modern submarine fans.
SEPM Special Publication (1060-071X) (Society for Sedimentary Geology), 2012 , Vol. 99 , P. 293-308

Droits : 2012 SEPM (Society for Sedimentary Geology)
http://archimer.ifremer.fr/doc/00129/24021/21978.pdf
http://archimer.ifremer.fr/doc/00129/24021/