TransFlux - Tracing for active dewatering sites along deep-reaching transform faults in the western Gulf of Cadiz, [METEOR] Cruise M86/5, February 23 –March 16, 2012, Palma de Mallorca (Spain) – Lisbon (Portugal)

Cruise M86/5 aimed at collecting data from potential fluid dewatering sites located in the deep-sea region of the western part of the Gulf of Cadiz and the adjacent deep sea plain. Previous work on mud volcanoes (cruises SO175 and MSM1/3) located on the accretionary wedge in the Gulf of Cadiz showed that mud volcano fluids are typically sourced at several km depth below the seafloor. In addition, the geochemical composition of fluids from the deepest mud volcano in this area which is located on a west-east trending transform lineament (SWIM1) indicated that these fluids are typical for having been altered by the reaction with oceanic crust. This implies that there is active flow connecting the oceanic basement and the seafloor. To date, such kind of hydrothermal circulation is only known for relatively young oceanic crust (