2.1. Stratigraphical insight
The drilled Cretaceous series in western Gulf of Gabes has encountered
two main units; a siliciclastic unit of Early Cretaceous age and an
intercalated evaporate and carbonate unit attributed to the Late Cretaceous.
The composite stratigraphic diagram summarizes all available
data from availablewells and clearly illustrates the complex distribution
of Cretaceous Formations and stratigraphic breaks in succession, the
result of coeval tectonic activity (Fig. 2).
The basal Melloussi Formation is comprised entirely of sandstone
unconformably overlying (U1 surface) the Nara carbonate and its lateral
equivalent, the M'Rabitine Member. The Boudinar Formation overlies
the Melloussi Formation and the total succession is interpreted as having
formed in a deltaic, alluvial plain environment (M'Rabet, 1981).
The relationship between this alluvial plain environment and the underlying
Nara carbonate suggests that there is a relative fall in sea
level at the unconformity U1, with a rejuvenation of the fluvial clastic
sequence as a result and a low-stand looding of the former carbonate
highstand systems tract. This is a classic relationship and should result