Facies and depositional environment of Saouaf Formation in North-east Tunisia (Cap Bon Basin)

Based on outcrop facies analysis in Cap Bon Basin (north-east Tunisia), the middle to upper Miocene succession can be divided into two parts, a lower one (mostly Langhian) represented by thin, widespread, open marine deposits... [ view full abstract ]

Based on outcrop facies analysis in Cap Bon Basin (north-east Tunisia), the middle to upper Miocene succession can be divided into two parts, a lower one (mostly Langhian) represented by thin, widespread, open marine deposits (marls and shelly limestones), and an upper one (Serravallian-Tortonian), represented by siliciclastic deposit. The latter is also marked by a dramatic increase in the subsidence rate. This latter time interval is represented, by the Beglia and Saouaf Fm. This series are made of a thick and monotonous pile of clay to sandstone coastal sequences.
This study focussed on the sedimentology and evolution of the upper Serravallian-Lower Tortonian Saouaf Fm. in two areas, the Jebels Abderrahmane and Bel Abiod in the Cap Bon peninsula.
In the Jebel Abderrahmane area, the Saouaf Formation (over 3000 m thick) is made of a large number of shallowing-up, clay to sandstone, coastal sequences, tidal and wave influenced.
At Jebel Bel Abiod the sequences are deepening-up, starting from channelled, tide-dominated, sandstone facies passing up to storm beds-bearing offshore clays. These distal sequences are thus interpreted as transgressive estuarine valley fills following forced regressions. The incised valley fills are nested in offshore claystone.
The updip to downdip facies relationships suggest that a previously unexpected system of lowstand prisms, could be connected to these valley fills northward in offshore Tunisia.