--> Abstract: Sedimentation and Role of Evaporites in Tunisia, by P. F. Burollet; #91012 (1992).

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ABSTRACT: Sedimentation and Role of Evaporites in Tunisia

BUROLLET, PIERRE F., CIFEG-GEA, Forcalquier, France

During Mesozoic and Cenozoic times Tunisia was generally in subtropical arid zones. Evaporites are common in the stratigraphic succession with various conditions of sedimentation.

The Triassic series, especially at their upper part, included thick halite and anhydrite as it was common in other parts of the Pangea. Later they had an important tectonic role with decollement features, diapirs, salt domes, and collapses.

In the Liassic and the Early Dogger, evaporites have been sedimented in the south, but elsewhere in Tunisia there was a carbonate platform.

With the Bathonian, a eustatic transgression and a rotation of Africa caused the disparity of the evaporites.

Some sulfates are interbedded in Early Cretaceous subdeltaic and internal shelf facies.

The Late Cretaceous corresponds to a transgressive time; sulfates were just sedimented in sheltered zones of the platforms, associated with laminated algal flats and dolomites.

On the border of the Eocene emerged lands of central Tunisia, local subsidence related to Triassic salt collapse resulted in the sedimentation of thick evaporites. For example 900 m of sulfates including halite dissolution levels are observed at Jebel Djebs near Maknassy.

Gypsum levels are interbedded in the Late Miocene paralic series and in the Messinian Oued Bel-Khedim Formation. An active subsidence in post-orogenic depocenters caused the accumulation of halite in the molasses of northeastern Tunisia.

Pleistocene coastal sabkhas and endoreic playas are characterized by a mixture of halite, sulfate, and clastics.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)