Episodes with reefal formations during the Aptian–Late Cretaceous in the gulf of Hammamet (Northeastern Tunisia): insights from seismic reflection and wells data

Abstract

In Tunisia, the Aptian–Maastrichtian period is characterized by the development of rudist-bearing carbonate platform. Through Aptian–Late Cretaceous period, rudist build-ups are associated with ramp systems, paleohighs, and tilted blocks. The platform growth was controlled either by the morphology of the antecedent substrate, or by sea level variation or by regional tectonic factors. In fact, eustasy accustomed the initial pattern of the rudist-bearing platform, while tectonics guided the geometry and the spatial distribution of platform facies and rudist build-ups. In the Gulf of Hammamet, a seismic interpretation and wells analyses helped us identify reef buildups and reconstruct the episodes of their development. Five episodes of Aptian–Upper Cretaceous platform units are distinguished by changes in platform geometry that are marked by facies variation. These episodes are characterized by a succession of distally steepened carbonate ramps from the Aptian to the Albian–Cenomanian period. During the Late Turonian, the carbonate platform has evolved into homoclinal ramp geometry. This morphology was reinforced by the Campanian compressive phase. Furthermore, ramps and their associated deposits and build-ups form prolific petroleum source and reservoir systems. They offer a range of subtle stratigraphic play types and lateral facies variations. Reservoirs can be found in mid or outer ramp isolated build-ups.