The role of methane seepage in the formation of the Northern Adriatic Sea geosites

Gordini, Emiliano; Donda, Federica; Tosi, Luigi; Bergamasco, A.; Andrea, Bergamasco; Donnici, Sandra

doi:10.1016/j.margeo.2023.107081

Cited by 2 publications

(2 citation statements)

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“…The considerable presence of gas in the analysed succession reflects what has been observed in the Plio‐Quaternary sediments of the northern Adriatic Sea (Gordini et al., 2023). Analysis of the gas samples has shown that biogenic methane is the main component of gaseous emissions at the sea floor (Donda et al., 2019).…”

Section: Discussionsupporting

confidence: 77%

“…The 'Tegnue' are localised at a depth between 10 and 40 m and can exhibit up to 3 or 4 m of positive local relief above the surrounding sea floor. Typically, they are located 2-17 km from the coast and at depths between 8 and 22 m (Zecchin et al, 2015;Minelli et al, 2021;Gordini et al, 2023). The early lithification of sand, which represents the substrate of the build-ups, can be related either to the interaction between salt water and fresh submarine groundwater (Tosi et al, 2017) or to gas seeps (Donda et al, 2013(Donda et al, , 2019Gordini et al, 2023).…”

Section: Discussionmentioning

confidence: 99%

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Evolution of a late Quaternary succession by interpretation of high‐resolution seismic and bathymetric data, Adriatic Sea

Da Col,

Zecchin,

Civile

et al. 2024

The Depositional Record

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This paper presents the results of the interpretation of a set of high‐resolution seismic lines integrated with multibeam echosounder data acquired in a coastal area in the Northern Adriatic Sea. The aim of the study was to reconstruct the stratigraphic evolution of a late Quaternary sedimentary succession offshore the town of Bibione, North‐Eastern Italy, by recognising the key unconformities, identifying the main depositional units, dating them and reconstructing the depositional environments in relation to relative sea‐level variations. Specifically, four sedimentary units, separated by erosional unconformities associated with the development of deep channels, were identified and dated based on literature information. By interpreting the seismic data, sedimentary dynamics were reconstructed and palaeoenvironments identified. The lower unit corresponds to a paludal environment, showing abundant gas seeps and accumulations (bright spots); the two intermediate units correspond to fluvial deposits, filling the deep incisions that characterise the bounding surfaces. Finally, the shallowest unit, bounded by a wave‐ravinement surface incised by tidal currents, corresponds to the Holocenic progradation of the coastal wedge. In addition, several vertical gas chimneys were identified, ranging in width from a few metres to 20–30 m. These were present in all units, often reaching the sea floor. Finally, elongated mounds, about 300 m wide, at the sea floor were recognised. The bathymetric and seismic characteristics of these elongated bodies and their relationship to adjacent sedimentary bodies suggest that they are probably methane‐derived carbonate formations known as ‘Trezze’ or ‘Tegnùe’. These names recall the fact that the trawls of the local fishermen were often hindered (‘tegnù’ in the Venetian language) or even cut off by these formations.

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Section: Discussionsupporting

confidence: 77%