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toe is visible in the outcrops — can be up to 15 metres.

Interpretation

As the name of the facies suggests, these deposits are interpreted as large — most likely isolated and
storm-related — prograding dunes. Outcrop data analysis shows that the crest of these dunes is parallel
to the Sicilian shoreline. The fact that no separate beds are present suggests that no interruption in
the amount of energy and/or sediment supply occurred — indicating a relatively steady depositional
environment without much variation.

4.3.6 Trough cross-stratified units

Description

These deposits consist up to several metres thick trough cross bedded bioclastic sands, with beds of
typically 10 to 40 cm thick. Locally a large amount of semi-broken bioclastic material is present, especially
at the base of a bed. This facies is dominating in several areas, such as the eastern part of Cala Rossa
and the outcrops of Bue Marino.

Interpretation

A higher energy supply to the system than in the case of dunes with a linear crest, implying higher Froude
numbers, induce a prograding dune to form an undulated crest. Troughs are forming in the concave
parts of the lee side of the dune. The undulating character causes these dunes to erode each other much
faster than a linear-type of dune — thick tabular foresets will not be able to develop — resulting in bed
thickness that differs significantly from the tabular dunes. A possible explanation for this observation
might be found in the increase in energy and the constant undulating crest, which partly erodes an earlier
deposited dune. The result is a system of intersecting troughs, showing a more chaotic architecture.
Figure 4.6b illustrates the geometry of such a dune system, including the appearance of so called ’troughs’
that are clearly visible on outcrop walls perpendicular to the main transport direction.

4.3.7 Massive bioturbated units

Description

The massive bioturbated units on Favignana show extensive burrowing, in some cases completely
obliterating the original sedimentary structure, while in other cases some bedding might still be visible.
Burrows can be both vertical and horizontal. The southern part of Favignana shows the most extensive

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