Therefore coexist ridge magmatism, hot spot magmatism and triple junction tectonic in predominantly submarine surroundings. The azorian Islands are at the top of a vast region strongly elevated when compared to the surrounding ocean floor, i.e., the Azores platform.
Hydrothermal vent fields
Hydrothermal vents are chimneys laying on the seafloor and formed by precipitation of primarily metal sulfides and sulfates when hot hydrothermal fluids mix with seawater. Black smokers are ejected with temperatures generally above 330ºC and the methane and sulphur concentrate in extremely toxic environments. These natural pollution labs are the new scientific enthusiasm of Azores, a kind of geothermic project of the XXI century, a new field full of commercial and research potentialities.
Submarine hydrothermalism in the Azores sea was known in 1992 when an American petrology mission dredged hydrothermal chimneys with living fauna, a real "Lucky Strike". In the follow year, the Alvin submersible visited for the first time the Lucky Strike hydrothermal field in a small mission where American, French and Portuguese scientists participated.
Four hydrothermal vent fields have been discovered in the South West of Faial Island: Lucky Strike (discovered in 1992), Menez Gwen (1994), Rainbow (1997) and Saldanha (1998). Nature distributed these four hydrothermal vents at different depths in the Atlantic ridge in a slow tectonic motion zone at divergent plate boundaries. Since then, important oceanographic missions have taken place there, in majority as a result of European projects.
