Geographical setting

 

The MoMARSAT cruise is exploring the hydrothermal vent site called Lucky Strike, located to the south-east of the Azores, at 1500 km from Lisbon.

 


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Lucky Strike

Hydrothermal zone Lucky Strike Position (Tour Eiffel edifice)
37.29°N
32.28°W

Situated near the Azores, the Mid-Atlantic Ridge is composed of four hydrothermal vent fields, each with different characteristics. The vent fields have been studied for many years by French and international scientists. Discovered in the 1990s, the Lucky Strike vent field has already been the focus of several research cruises.

Located at 1700 m depth at the summit of a central seamount with a shallow magma chamber, the vent field is made up of some one hundred hydrothermal vents that surround a former lava lake. Temperatures range from 330°C at the hottest vents to barely 20°C at diffuse emissions. The chemistry of the hydrothermal fluids indicates a complex hydrothermal system.

The biological communities associated with smokers are composed of vent mussel beds colonised by microbial mats or, in the hottest areas closest to the chimneys, swarms of vent shrimp. Many deep-sea fish visit these sites, looking for a meal. The food chain is based on chemosynthesis, i.e. microorganisms at the base of the chain utilise energy from the chemical compounds present in the fluids to synthesise organic matter. These microorganisms are grazed or, when they are free-living, filtered; some even live in symbiosis with invertebrate species.