Deep and shallow gas occurrence in the NW Sicilian Channel and related features

In this paper we present a combined analysis of recent swath bathymetric data, very high-resolution seismic and multi-channel seismic profiles, integrated with a vintage crustal seismic profile, acquired in the NW Sicilian Channel (Central Mediterranean Sea). These data have been analyzed with the main aim of studying the gas presence and related features in both the subsurface and at the seafloor, through the recognition of amplitude and velocity anomalies in the entire Miocene-Pleistocene sedimentary succession. Our results shed light on the possible gas origin and migration mechanisms. In particular, we support the hypothesis of a gas derivation by thermal cracking of organic matter and suggest the shaly/marly intercalations hosted in the Meso-Cenozoic carbonate succession as a possible source rock. Deep lithospheric faults systems and associated fractures provide preferential paths for gas migration and accumulation in the Miocene-Quaternary sandy and carbonate layers. Gas is then able to locally reach the seafloor originating positive (mud volcanoes) and negative (pockmarks) morphologies.