Venting and seepage systems associated with mud volcanoes and mud diapirs in the southern Tyrrhenian Sea

High resolution swath bathymetry and backscatter data, seismic CHIRP profiles, multibeam water column acoustic measurements and sediment samples were collected on a cold seep province in the southeastern Tyrrhenian Sea, at a water depth of 500-1000. m. The mud volcanoes, characterized by a high backscatter signature, are the site of gas venting at the seafloor that formed a 630-m-high plume in the water column. The mud volcanoes feature a precipitation of iron-oxy-hydroxide crusts and pyritized and Sulfur burrows in the sub-surface and authigenic siderites, also cementing burrows, further down, showing a sharp transition from the oxic zone toward the sulfate-methanogenic zone.The mud flows are characterized by an intermediate backscatter seafloor and by the presence of gas in the sediment only 2. m below the seafloor. The mud flows consist of 1-m-thick drapes of water-rich mud extending downslope from the mud volcanoes. They act as sealing layers that prevent large fluxes of gas venting at the seafloor (low venting) and favor oxic conditions close to the sediment-water interface and the abundant precipitation of post-oxic siderites a few meters below the seafloor.The mud diapirs are characterized by a low backscatter seafloor and large fields of pockmarks. In coincidence with the normal faults, organogenic carbonate crusts form at or very close to the seafloor and are associated with chemosymbiontic bivalves (lucinids). The youngest shells are AMS radiocarbon dated 640-440. BP, suggesting that the seepage activity may have been clogged by the carbonates, only very recently.Similarities between the normal faults in the study area and the tectonic setting of the inland Calabrian Arc show that normal faults can control the location of fluid pathways and, probably, also the rising of the mud diapir

“HABITAT MAPPING” GEODATABASE, AN INTEGRATED INTERDISCIPLINARY AND MULTI-SCALE APPROACH FOR DATA MANAGEMENT

<p>Abstract</p> <p>Historically, a number of different key concepts and methods dealing with marine habitat classifications and mapping have been developed to date. The EU CoCoNET project provides a new attempt in establishing an integrated approach on the definition of habitats. This scheme combines multi-scale geological and biological data, in fact it consists of three levels (Geomorphological level, Substrate level and Biological level) which in turn are divided into several hierarchical sublevels. This system allows to identify, describe and map in a consistent way habitat distribution from shallow coastal to deep sea (Foglini et al, 2014). </p> <p>Starting from this idea, we have designed and developed a ESRI File Relational Geodatabase (GDB) dedicated to habitat mapping, focusing particularly on storage and management of groundtruthing data and products. In the GDB, the contents are organized in three major groups as follows: the SamplingFeatures dataset stores the elements related to the sampling, the ROVs dataset groups all the information about the ROV surveys and, the maps are located in the HabitatMaps dataset. According to the CoCoNET classification scheme, we have the Geomorphological layer, the Substrate Layer and the Biological layer, and from the sum of these levels we obtain the Habitat layer. The hierarchical structure allows building maps with several possibilities of combination between all the levels, so we can produce multi-scale outputs and legends. </p> <p>An innovative approach is adopted for processing ROV dives. The video tracks are analyzed with the Adelie software and are represented with: (i) the ROV navigation, (ii) the habitat description (also this Habitat layer is organized according to the CoCoNET classification levels), (iii) the heading of the ROV cameras, (iv) the georeferenced position of the images along the path and (v) the biological samples. While the images are stored in the GDB, the videos are linked through a hyperlink and can be visualized on the ROV navigation lines with the Adelie software. </p> <p>An organized system, such as the “Habitat Mapping” GDB, is crucial for a correct data management, since it allows to store, visualize, query and elaborate data to produce customized maps in an easy and efficient way. Moreover the use of the CoCoNET classification scheme gives to the system a multidisciplinary and multi-scale trait, essential while dealing with habitat mapping.</p> <p>The presentation was performed during the International Congress GeoSUB 2015, Trieste, 13-14 October, 2015.</p

Habitat mapping in the Adriatic (Mediterranean Sea): approaches and methodologies for assessing seafloor habitat from coastal areas to deep sea

The knowledge about habitat distribution and extent is critical for the conservation and the management of the marine system and is a fundamental pre-requisite to allow for an adequate representation of all physical and biological typologies. Moreover, habitat maps represent the basic tool for the reconstruction of submerged panoramas relevant to any future geo-archaeological and prehistoric investigations. In the framework of the E.U. COCONET project (Towards COast to COast NETworks of marine protected areas from the shore to the high and deep sea) we make and attempt in establishing a unified approach on the definition of habitats. Our scheme combines multi-scale geological, oceanographic and biological data, to identify, describe and map in a consistent way habitat distribution from shallow coastal to deep sea