Bacterial colonies and manganese micronodules related to fluid escape on the crest of theMediterranean ridge

A black, few centimeters thick Marker-bed of Holocene age is consistently recorded in all the deep-sea cores raised from two fields of mud diapirs recently discovered on the crest of the Mediterranean Ridge south of Crete. Detailed investigations on the ultrastructure of the Marker-bed accompained by micro-probe analysis revealed the occurrence of Mn-rich micronodules and bacterial colonies in very high number. Their occurrence is accounted to fluid escape in the accretionary prism, related to mud diapirism and tentatively associated with an important volcanic event occurred in the arc-trench system.