HR: 11:20h
AN: V22C-05    [Abstracts]
TI: Seismic Imaging of Mud Volcanoes on the Calabrian Arc Accretionary Prism, Central Mediterranean Sea
AU: * Ceramicola, S
EM: sceramicola@ogs.trieste.it
AF: Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/c, Sgonico, Trieste, 34010, Italy
AU: Praeg, D
EM: dpraeg@ogs.trieste.it
AF: Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/c, Sgonico, Trieste, 34010, Italy
AU: Wardell, N
EM: nwardell@ogs.trieste.it
AF: Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/c, Sgonico, Trieste, 34010, Italy
AU: Unnithan, V
EM: v.unnithan@jacobs-university.de
AF: Jacobs University Bremen, School of Engineering and Science, P.O. Box 750 561, Bremen, 28725, Germany
AB: A new province of mud volcanoes was discovered on the Calabrian Arc during the HERMES-HYDRAMED IONIO 2005 campaign of the Italian research vessel OGS Explora. Short-offset (600 m) 2D & 3D seismic reflection data were acquired from a feature referred to as the Madonna dello Ionio, which lies on the inner Arc, c. 40 km from the Calabrian coast, in water depths of 1650-1850 m. The Madonna comprises an elongate fault-bounded seabed depression containing three circular extrusive features, including a pair of cones, each up to 150 m high and 1.5 km wide. The latter were the targets of the 3D seismic survey, involving the acquisition of 109 closely-spaced (c. 25 m) short-offset profiles; CMPs were assigned to 25 m bins to obtain an average data fold of 84 over a 2.8 x 5.9 km area, then migrated (2-pass finite difference) using velocities available for the upper second sub-seabed. The 2D & 3D data together provide information on the extrusive cones and their shallow (<1 km) rooting structure. The 3D imagery reveal the seabed cones to be underlain by offset buried cones that interfinger with the upper 300 ms of flanking Plio-Quaternary strata, indicating extrusive activity over a long period (perhaps more than 1 million years). Cross-cutting reflections beneath the mud volcanoes suggest the presence of fluids and gas (including possible hydrates) within the structure. The rooting structure is seen to comprise a relatively narrow (<1 km) central conduit surrounded by a broad zone (3-4 km) of sediment that is complexly structured (low reflection continuity), which may have been disturbed in situ or emplaced beneath the mud volcanoes. The seabed cones are flanked by on one side by normal faults with seabed expression, recording recent movement that may be in part due to subsidence induced by the extruded material, but that is inferred to be linked to an underlying fault that has localised the activity of the mud volcanoes in space (and perhaps over time, in response to compressional episodes on the Calabrian Arc).
DE: 3000 MARINE GEOLOGY AND GEOPHYSICS
DE: 3004 Gas and hydrate systems
DE: 3025 Marine seismics (0935, 7294)
DE: 3045 Seafloor morphology, geology, and geophysics
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting