Page 4 - Frixa_Miuccio_Paleog-evolution_EAGE

- To the north-west there was a marked hiatus between the Cretaceous and Eocene which can
be attributed to a significant regional Oligocene erosive event, linked to the formation of
Mazara High. Large accumulations of “megabreccia” outcropping in western Sicily are linked
to this event (CATALANO et al., 1982).

KEYWORDS: Sicily offshore, foreland, facies, platform domain, basinal domain, subsurface
data, carbonate, stratigraphy, sedimentology.

PALAEOGRAPHIC EVOLUTION

During the Late Triassic, the Hyblean-Saccense carbonate platform (Sciacca Fm.) was
characterised by dolomitic tidal deposits with local open shallow platform episodes.
In the southern and western offshore and in the Egadi islands (Abate et al., 1982), frequent
evaporitic interbeddings are present; these are linked to a gradual change in the depositional
environment towards sabkha conditions, typical of the Tunisian domain (Adiadj Fm.).

Fig. 2. Areal distribution of the Middle-Lower Liassic facies

Eastwards, in the Hyblean foreland, the Triassic platform changes, through marginal facies, to an
euxinic basin environment (Streppenosa Fm.). This basin extended to most of the Hybaean
offshore and onshore (ANTONELLI et al., 1988, FRIXA et al., in press).
In the Saccense offshore, some small local triassic-liassic basins, characterised by carbonate-
argillaceous interbeddings, occur.

During the Early and Middle Lias (Fig. 2) the carbonate platform conditions (Inici Fm.)
extended throughout the Saccense offshore and onshore. In this domain, the facies is generally
that of a restricted or tidal platform with local high-energy events.
Towards the east (Hyblean sector) there is an increase in high-energy levels. The margin of the
platform is clearly marked by the appearance of slope facies (Rabbito Fm.), that prelude to more
markedly basinal sediments (Modica Fm.).
Also in the north-west it is possible to recognize a slope depositional environment, outcropping
in the Egadi Islands and referred to as the Monte Falcone Unit (ABATE et al., 1982). In the
offshore, basinal carbonate deposits were drilled north of the Egadi islands.

From the Toarcian (Fig. 3) the carbonate platform could have emerged, mainly in the
southernmost sector of the offshore, where there was lack of sedimentation up to the Neocomian.

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