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exhumation occurred in the offshore, source rocks could be still generating oil at present day at depths of 2.5 km to 4.5 km, the Cenomanian-
Turonian source rocks are expected to occur within this interval.

Conclusions

The analysis of new geochemical data indicates hydrocarbons from seeps in western Sicily within the Trapanese domain are most likely
derived from Late Triassic-Liassic intraplatform basins. These basins extend offshore in the inverted Tortonian-Messinian foredeep and foreland,
providing the source rock for some of the hydrocarbons discovered in the area. Geochemical data have shown a possible correlation between these
hydrocarbons and the oils generated by Late Triassic source rocks in the Ragusa Basin in southeastern Sicily, where prolific oil fields have been
discovered. However hydrocarbon seeps in western Sicily were generated from source rocks deposited in a more restricted marine environment
characterized by carbonate sedimentation and absence of any clastic input. Although Triassic – Liassic source rocks are likely to contribute to the
petroleum system of the offshore Sicilian thrust belt, the most prolific source rock of the area is considered to be the Cenomanian-Turonian black
shale known as Bahloul Formation in North Africa. These sequences were sampled onshore Sicily and displayed the highest source rock potential of
all the analyzed samples. Analysis of geochemical data concluded that these sequences developed in a near-shore environment, likely within slope
facies of the Panormide platform. Our studies suggest hydrocarbons were generated from a Cretaceous source rock, possibly the Fahdene Formation
(Aptian-Albian) or more likely the Bahloul Formation (Cenomanian-Turonian) within the offshore thrust belt from Late Miocene to the present day.
These hydrocarbons migrated towards the inverted foredeep-foreland forming the oil accumulations of Nilde and Norma during the Plio-Pleistocene.
Tertiary source rocks, although prolific in Tunisia and Sicily, are not expected to significantly contribute to the hydrocarbon system of the offshore
Sicilian thrust belt.

References

Avellone, G., M.R. Barchi, R. Catalano, M.G. Morticelli, and A. Sulli, 2010, Interference between shallow and deep-seated structures in the Sicilian
fold and thrust belt, Italy: Journal of the Geological Society (London), v. 167/1, p. 109-126. DOI: 10.1144/0016-76492008-163.

Basilone, L., 2009, Sequence stratigraphy of a Mesozoic carbonate platform-to-basin system in western Sicily: Central European Journal of
Geosciences, v. 1/3, p. 251-273.

Cavazza, W., J. Blenkinsop, P.G. de Celles, R.T. Patterson, and E.G. Reinhardt, 1997, Stratigraphy and sedimentology of the Oligocene-Quaternary
sedimentary sequence in the Calabrian-Ionian Basin: Bollettino della Societa Geologica Italiana, v. 116/1, p. 51-77.

Catalano R., S. Merlini, and A. Sulli, 2002, The structure of western Sicily, central Mediterranean: Petroleum Geoscience: v.8, p. 7-18.