Fig. 4
Seismic characteristics of magma-induced hydrothermal buried systems as the source of seafloor craters. (A) Multibeam bathymetry mosaic along the seismic line displayed in (B) showing elongated sea-floor craters labelled as 1–4. (B) Seismic line showing the complete hydrothermal buried system formed above a complex of interconnected (steeped) sills. Seabed craters are connected throughout fluid pipes above the forced folds formed by the intrusion of the steeped sills. (C) Detail of forced folds formed above the reservoir as consequence of generation of thermogenic methane. (D) Detail of V-shaped fluid pipe at the edge of the sill complex. (E) Seismic image of the hydrothermal buried system formed above a single saucer shaped sill. A gas chimney is formed in the centre of the sill breaching the opal diagenetic layer. (F) Detail of the seismic expression of a single saucer-shaped sill, 7 km long and 160 m-thick, characterized by two strong positive reflections surrounding a negative reflection. Location of seismic lines is shown in Fig. 1.
