Growth of late Lower to Upper Cretaceous isolated carbonate platforms: New insights from the Pelagian sea (Gulf of Hammamet, Tunisia)

Abstract

This paper examines the evolution and the drowning history of late Lower to Upper Cretaceous carbonate platforms in the Gulf of Hammamet, belonging to the North eastern of Tunisia based on seismic and well data sets. We use seismic architecture, well log data and micro-fauna to reconstruct factors that governed the growth and demise of the platforms. Platform evolution reflects four stages: (1) initial installation, (2) platform aggradation, progradation and retrogradation, (3) coalescence and extension, and (4) burial by Cenozoic siliciclastic deposits. Interpretations of seismic facies help to define platform history indicating that the area of study originated since the Jurassic time as three small platforms on extensional fault-blocks separated by deep seaways. Eustatic sea-level changes controlled the timing of sequence boundary establishment. Nevertheless, tectonics modified facies distributions and stacking patterns. Faulting-controlled the substrate morphology, forming-sites for the development of platform deposits and providing bottom for the localization of backstageped platforms. Faulting may also have caused progradation of the platforms as a result of a slowdown in the creation accommodation space. The net platform extension and backstageping may be controlled by regional subsidence. Progradation is highly developed on the leeward sides of the platforms, but increased accommodation resulting either from rapid local subsidence or changing oceanographic currents also influenced the direction and magnitude of the results.