|Abstract||The MOMAR08-Leg 1 cruise combined three different scientific programs within the MoMAR project :
- RECO (PI : P. M. Sarradin) : Ecology and environment
- Graviluck (V. Ballu) : Seafloor geodesy
- Bathyluck (J. Escartin) : Temperature and seismic monitoring
The studies are concentrated on the Lucky Strike volcano on the Mid-Atlantic Ridge at 37°N. The volcano hosts a large hydrothermal site and overlies one of the only magma chambers that has been imaged on a slow-spreading oceanic ridge. The hydrothermal site has been the site of continuous biological and geochemical experiments for more than a decade, and will be the site for a future seafloor observatory to be initiated with the MOMARSAT program (pre-programmed for 2010).
The main goal of the cruise was the recovery of instrumentation deployed in 2006 (MOMARETO and GRAVILUCK cruises) and 2007 (MOMAR’07 cruise), including the TEMPO module, autonomous temperature sensors, pressure gauges and microbiological colonizators. A second objective was the deployment of autonomous sensors for temperature and pressure, and microbiological colonizators, to continue monitoring of the site into 2009. These operations were complemented with biological chemical and microbiological measurements and sampling. A third objective was the detailed characterization of the Lucky Strike site in general and the hydrothermal vents in particular. This was achieved with the imagery acquire during visits to the instrumented sites, and during the high-resolution survey using the Module Route (OTUS B&W imagery and multibeam bathymetry and acoustic backscatter). The original program of temperature sensor deployment had to be modified owing to technical problems (corrosion and deterioration of sensors after short deployments).
The first part of the cruise (VICTOR dives 1-4) was carried out using the “Module de Prelevement”, for sample and instrument recovery and deployment. Transfer of material between the surface and the seafloor were carried out with an elevator (NASA) to minimize the number of dives and thus maximize the time at the bottom. The second part of the cruise included three OTUS and multibeam surveys at the Lucky Strike vent field (8 m height) and two 50-m multibeam surveys extending the mapping obtained during MOMARETO. This survey was carried out during a single dive.
A section of the Bathyluck Project included the recovery and deployment of ocean bottom seismometers (OBSs) from the national INSU instrumentation pool to monitor microseismicity over the periods 2007-2008 and 2008-2009. This was carried out during the BBMOMAR-2 cruise onboard Suroit (PI : W. Crawford; BO Suroit, 7-18/08/2008).
Aspects of this projects were supported by MOMARNET (EU), ANR (France) and EXOCET/D (EU) projects, in addition to the cruise support and ship time provided by INSU and IFREMER.
Escartin Javier (2009). MoMAR’08 – Leg 1 (Lucky Strike). Cruise Report. 9-24 Aug 2008.N/O Atalante – Victor 6000. https://doi.org/10.13155/47148