HR: 1340h
AN: T13B-0455    [Abstracts]
TI: Newly Imaged Mud Volcanic Province on the Calabrian Arc in the Central Mediterranean Sea: Preliminary Results from Cruise HERMES-HYDRAMED IONIO 2005
AU: * Ceramicola, S
EM: sceramicola@ogs.trieste.it
AF: Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/c, Sgonico, 34010 Trieste, Italy, 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, 34010 Trieste, Italy, Trieste, 34010 Italy
AU: Cova, A
EM: acova@ogs.trieste.it
AF: Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/c, Sgonico, 34010 Trieste, Italy, Trieste, 34010 Italy
AU: Monteys, X
EM: Xavier.Monteys@gsi.ie
AF: Geological Survey of Ireland (GSI), Haddington Road, Dublin, Dublin 4 Ireland
AU: Unnithan, V
EM: v.unnithan@iu-bremen.de
AF: International University Bremen (IUB), GmbH Campus Ring 1, Bremen, D-28759 Germany
AU: Garziglia, S
EM: garzi@geoazur.obs-vlfr.fr
AF: Geosiences Azur, Observatoire Oceanologique de Villefranche sur mer -, B.P.48, Villefranche sur mer, 06235Cedex France
AU: Explora Scientific Party, O
EM: sceramicola@ogs.trieste.it
AF: Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/c, Sgonico, 34010 Trieste, Italy, Trieste, 34010 Italy
AB: We report the discovery of a new province of mud volcanoes in the northern Ionian Sea (Central Mediterranean Sea) during the summer 2005 campaign of the Italian research vessel OGS Explora. The campaign was undertaken in the framework of the EC Integrated Project HERMES (Hotspot Ecosystems Research on the Margins of European Seas), in cooperation with the EC Marie Curie project HYDRAMED (Assessment of Gas Hydrates in the Mediterranean Sea). The purpose of the campaign was to investigate shallow fluid/gas escape processes on the Calabrian Arc, an accretionary prism resulting from the subduction of the African below the European plates, which was thought likely to contain features of mud volcanism of interest for both HERMES and HYDRAMED by analogy with the larger accretionary prism of the Mediterranean Ridge. The 5 week campaign resulted in the acquisition of multibeam bathymetric imagery (accompanied by Chirp subbottom profiles and gravity measurements) across a wide area of the Calabrian Arc, as well as multichannel seismic reflection data and gravity cores from selected mud volcanic features. Multibeam data was acquired over an area of about 225 x 160 km, covering depths from 1500 to 3500 m, and reveals the large-scale tectonic structures of the inner and outer Calabrian Arc. Features of mud volcanism were identified at seabed on both the internal and the external Calabrian Arc, in water depths of 1900-2300 m. On the internal Arc, in the Spartivento Basin, a pair of conical mounds referred to as the Gemelli, each up to 200 m high and 1.2 km wide, lie within an elongate seabed depression that also bounds a third circular feature of low relief to the northeast. Seismic data indicate the seabed depression to be structurally controlled and show the Gemelli to comprise unstratified lenses up to 300 ms thick within a Plio-Quaternary succession. On the external Arc, 60 km to the south, a circular feature up to 250 m high and 8 km wide, referred to as the Ciccione, is the top of a sediment cone that extends at least 2 seconds below seabed above inward dipping reflectors. Gravity cores from both the Gemelli and the Ciccione proved grey mud breccias (diamicts containing angular sedimentary clasts to cobble size) to lie at or near seabed, suggesting recent mud volcanic activity. One week of the campaign was dedicated to the acquisition of seismic reflection data across the Gemelli in order to construct a high-resolution 3D-seismic volume. A grid of 109 short-offset (600 m) multichannel profiles were acquired at a nominal spacing of 25 m across an area of 2.8 x 4.5 km. The data is currently being processed into a 3D-seismic volume that will be used to examine the geometry and internal structure of the mud volcanoes and their relation to underlying structures, as well as to indicators of shallow gas and/or fluids and possible salt lenses. In the coming months processing of the raw multibeam data and analysis of the gravity data will be completed in order to better constrain the presence and character of fluid and gas escape features.
DE: 3002 Continental shelf and slope processes (4219)
DE: 3075 Submarine tectonics and volcanism
DE: 4219 Continental shelf and slope processes (3002)
SC: Tectonophysics [T]
MN: Fall Meeting 2005