Sources of mud volcano fluids in the Gulf of Cadiz—indications for hydrothermal imprint

Ferromanganese nodules and micro-hardgrounds associated with the Cadiz Contourite Channel (NE Atlantic): Palaeoenvironmental records of fluid venting and bottom currents

“…The migration of fluids through these structures includes gas, oil and also water with dissolved ionic components in solution (e.g. Hensen et al, 2007). Enrichments of Fe, As and Mo have been discovered in sediments affected by fluid venting from the Malta Plateau area and are interpreted as geochemical markers of fluids ascending towards the sediment surface (Cangemi et al, 2010).…”

“…In mud volcanoes of the area radiogenic venting fluids have been reported to appear directly in the pore fluids, with 87Sr/86Sr isotopic values of up to 0.7099-0.7106 (e.g. Hensen et al, 2007;Scholz et al, 2009). Therefore, high 87Sr/86Sr isotopic values (0.70993 ± 0.00025; 0.70992 ± 0.00023) observed in the inner parts of nodules (Fig.…”

“…The fluids are probably generated by c1ay mineral dewatering, promoting volcanic activity episodes at the seafloor. Deep thermal maturation of c1ay minerals has been proposed in the Gulfof Cadiz and other areas affected by mud volcanism to explain the mineralogical nature of mud extrusions (Hensen et al, 2007;Martín-Puertas et al, 2007;Blinova et al, 2011). The diagenetic transformation of smectite…”

Sobre algunas especies de frenulados (Annelida: Polychaeta: Siboglinidae) de los volcanes de fango en el golfo de Cádiz (NE Atlántico)

“…The compression between the Eurasian and African tectonic plates creates an interesting geophysical template (Sartori et al, 1994;Maldonado et al, 1999;Gutcher et al, 2002) shaped by volcanic activity and by the interaction between the topography and the circulation of the Atlantic and Mediterranean Waters (Peliz et al, 2007). Found in water depths between 200 and 4000 m, these mud volcanoes are clustered in several fields on the Portuguese, Spanish, and Moroccan margins and show considerable variations in dimension, morphology and composition of erupted material and fuids (Pinheiro et al, 2003;Van rensbergen et al, 2005;Hensen et al, 2007;niemann et al, 2006).…”

“…This diversity is probably due to the variety of geological and physical settings. Apart from differences in activity and fluid composition (Pinheiro et al, 2003;Van rensbergen et al, 2005;Hensen et al, 2007;niemann et al, 2006), mud volcanoes situated in the deeper areas of the Gulf of Cadiz are under the influence of deep Atlantic water masses, whereas the shallower mud volcanoes are strongly influenced by the Mediterranean outflow Water (Peliz et al, 2007). This environmental heterogeneity, acting on larvae dispersal and settlement, is likely to lead to high diversity of frenulates.…”