publications

Article

Paleoenvironment and genesis mode of Senonian rudist reef complex in Jebel el Kebar, central Tunisia

NEGRA Mohamed Hédi, 2016

Bulletin de la Societe Geologique de France, III, 8, 317-326, Juin 2016

Résumé

Campanian-Maastrichtian micritic limestones, locally rich in rudists and corals, outcrop at the south western periclina1 ending of Jebel el Kebar, central Tunisia. They constitute the Merfeg Formation. The reef character of th.is formation is mainly shown by the lenticular morphology of bodies, totally or partially built up by rudists and corals. Other lenticular and asymmetric bodies arc formed essentially of micritic piles in which organic builders are scattered. The asymmetric morphology of these micritic mounds and current structures indicate, at least partially, control of hydrodynamic factors. Lens-shaped rudist limestones (bioconstructed and micritic) arc laterally relayed by conglomerates containing pebbles and blocks reworked from the lenticular limestones and trapped in adjacent depressions. The frequency of these conglomerates and the diagenetic characters of the lenticular limestones indicate an early lithification related to a probable intra-Senonian emersion. Thus, the origin of rudist lenses in Jebel el Kebar involves many processes such as formation of micritic piles, rudist-coral construction, early lithification of the lenticular bo