The non-marine charophytes-rich Aptian-Albian records in Central Tunisia (Jebel Ksaïra)

The Aptian-Albian transition was marked, in the platform domain (central Tunisia) by a major stratigraphic gap linked with a subaeral exposure. This gap was however recorded in the region of Sidi Bouzid by a non-marine series... [ view full abstract ]

The Aptian-Albian transition was marked, in the platform domain (central Tunisia) by a major stratigraphic gap linked with a subaeral exposure.
This gap was however recorded in the region of Sidi Bouzid by a non-marine series rich in charophytes, called "Kebar Formation". This formation -that was previously considered exclusively continental and remains non dated- has been reviewed in its Type locality so-called Jebel Kebar based on a careful study of Charophytes and Ostracods associations by Trabelsi et al. (2012). These authors have, for the first time, attribute the Kebar formation to Upper Aptian (Gargasien-Clansyesien)-Lower Albian, and interpreted the sedimentary environment, as a continental to margino-littoral basin (Kebar basin).
The study of the same formation and associated charophytes and ostracods in another locality in the Sidi Bouzid region: so-colled Jebel Ksaïra, situated 4 Km east of Jebel Kebar, provided more chronostratigraphic informations. In particular, it was possible to show that the base of the Kebar formation is in fact younger than it is equivalent in Jebel Kebar. Indeed, a new charophyte species has been discovered allowing us to ascribe the lower part of the Kebar Formation in Jebel Ksaira to Lower Aptian.
The sedimentological analysis of the Kebar Formation in Jebel Ksaira, while considering the associated charophytes and ostracods, show that this formation includes different depositional facies that have developed within different sedimentary environments. In fact, it seems that the Jebel Ksaira locality has been evolved on the eastern border of the Kebar basin, within an environment that oscillated between a continental domain (lacutrine to palustrine) and a margino-littoral strip (lagoonal). The sedimentary deposition was alternating between (i) continental deposition materialized by bedded limestone rich in charophytes and limnic ostracods and (ii) margino-littoral deposition associated to conglomerates contemporaneous with salt tectonics (diapirs of Jebel Rheouis).
Regarding such new data recovered from Jebel Ksaira locality, it seems interesting to revaluate the geographic extend and the morphology of the Kebar Formation in Central Tunisia.

Keywords: Aptian-Albian – Charophytes – Ostracods – Kebar Formation – Jebel Ksaïra – Central Tunisia.