Fossil microbial evidences from Miocene Roccapalumba (Central Sicily, Italy) methane-seep carbonates.

A Lower Miocene seep-carbonate accumulation crops out near the town of Roccapalumba (western Sicily) and exhibits both geo-paleontological and geochemical (carbon stable isotope values) diagnostic features. This carbonate deposit mostly consists of foraminiferal-bearing authigenic micrite with a detrital siliciclastic component, and the abundant macroinvertebrate assemblage is dominated by densely packed lucinid-like shells. Acomplex network of veins and cavities, presumably used by a diffuse and continuous (H2S-enriched) fluid flow migration or seepage, occurs in this fossil seep. This network is filled by microbial-interpreted fabrics and sedimentary textures including peloids and spheroids, biominerals (e.g. framboidal pyrite), biofilms, crusts and corrosion surfaces. Microbial induced fabrics and textures are interpreted as the fossil remains of the intense activity displayed by seep-related microbial consortia.