Éditeur(s) : American Geophysical Union
Résumé : We present new high-resolution bathymetry and backscatter data acquired in 2006 with the ROV Victor 6000 over the Lucky Strike hydrothermal field, Mid-Atlantic Ridge. As long-term monitoring of the Lucky Strike area (MoMAR project) is being implemented, these new high-resolution data offer an unprecedented view of the distribution of hydrothermal edifices, eruptive facies, and small-scale tectonic features in the Lucky Strike vent field. We show that vents located in the NW and NE correspond with wide expanses of lumpy seafloor which we interpret as primarily made of broken chimneys and sulfide edifices. They are found above scarps with relief > 50 m or on associated mass wasting deposits. By contrast, the SE and SW vents correspond with small expanses of lumpy seafloor and are located near smaller scarps which we interpret as more recent faults. Hydrothermal edifices in the SW venting area appear very recent, postdating the emplacement and faulting of the most recent lava. We propose that this difference in the age of hydrothermal edifices does not mean that hydrothermal venting itself is more recent in the southern part of the Lucky Strike field because preexisting sulfide deposits there may have been buried by recent volcanic deposits. Instead, the older edifices in the northern part of the hydrothermal field may have been allowed more time to grow because they are set above the level of recent lava flows. The formation of a lava lake is the most recent eruptive event detected at Lucky Strike. Lava drainback is evidenced by benches and lava pillars, suggesting a close connection with an underlying magma reservoir, which probably corresponds to the melt body imaged by Singh et al. (2006). We have found no evidence that this lake was active for months to decades, as lava lakes at terrestrial volcanoes. It may instead have formed as a lava pond, with successive lava flows covering the eruptive vents, as proposed for similar features at the EPR. The horizontal surface of the lake is deformed only near its southwestern shore, along a NNE-trending set of faults and fissures, which appear to control the distribution of hydrothermal chimneys.
Geochemistry Geophysics Geosystems (1525-2027) (American Geophysical Union), 2009-02 , Vol. 10 , N. 2 , P. 1-18

Droits : 2009 American Geophysical Union
http://archimer.ifremer.fr/doc/2009/publication-6161.pdf
DOI:10.1029/2008GC002171
http://archimer.ifremer.fr/doc/00000/6161/

Éditeur(s) : Taylor and Francis
Résumé : A new cumacean genus and species, Thalycrocuma sarradini gen. et sp. nov., belonging to the family Nannastacidae is described from several sites of the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge, 37N, 1700 m depth). The new genus differs from others in the family by males lacking exopods on the pereopods 3 and 4 and having an antenna with a five-articulate peduncle and a short flagellum. This is the first cumacean species that could be considered, at the moment, as endemic from hydrothermal vent areas. Data on the accompanying fauna including other cumacean species (Cyclaspis longicaudata, Bathycuma brevirostre, Procampylaspis sp. and Makrokylindrus sp.) and some ecological remarks are included. A key for the currently known genera of the family Nannastacidae is provided and the taxonomic position of some genera is discussed.
Marine Biology Research (1745-1000) (Taylor and Francis), 2008-06 , Vol. 4 , N. 3 , P. 180-192

Droits : 2008 Taylor & Francis Group
http://archimer.ifremer.fr/doc/2008/publication-4358.pdf
DOI:10.1080/17451000801898576
http://archimer.ifremer.fr/doc/00000/4358/