The Origin of Gas Seeps in the Northern Adriatic Sea

• Published in: Italian Journal of Geosciences
• Main Authors: Donda, Federica, Tinivella, Umberta, Gordini, Emiliano, Panieri, Giuliana, Volpi, Valentina, Civile, Dario, Forlin, Edy, Facchin, Lorenzo, Burca, Mihai, Cova, Andrea, Ferrante, Giulia M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Italian Geological Society 2019
• Subjects: VDP::Mathematics and natural science: 400::Geosciences: 450::Hydrogeology: 467; VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Hydrogeologi: 467; Gas seeps; Methane; Fluid flow in porous media; Isotope geochemistry; Northern Adriatic Sea; VDP::Mathematics and natural science: 400::Geosciences: 450::Mineralogy; petrology; geochemistry: 462; VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Mineralogi; petrologi; geokjemi: 462; Arctic
• Online Access: https://hdl.handle.net/10037/15866; https://doi.org/10.3301/IJG.2018.34

Source at https://doi.org/10.3301/IJG.2018.34 . A multidisciplinary approach has been used for the first time to study the widespread occurrence of hydrocarbon seeps in the northern Adriatic Sea. Geological, geophysical and geochemical analyses were performed to identify and characterize the gas-charged fluids occurring throughout the Plio-Quaternary succession, and to date the shallow gas seeping at three leakage sites. The analysis of CHIRP, morpho-bathymetric, and multichannel seismic data allowed us to identify different types of gas-related features, which occur within the whole Plio-Quaternary succession up to the seafloor and to the water column. Quantitative analyses of CHIRP data were conducted to better define, characterize and quantify the gas occurrence within the uppermost stratigraphic succession. CHIRP data also allowed identifying the gas leakage sites. Three gas seepages areas were sampled with the aim to determine the gas composition and origin. The isotopic analyses revealed that seep gases are microbial in origin, and are primarily composed by methane, mostly formed within relatively laterally persistent Late Pleistocene peat layers, which are widely distributed throughout the northern Adriatic Sea and represent the main source of organic matter feeding the seeping gases.