Découverte de graptolites d'âge Caradocien dans quelques sondages du Tinrhert (Sahara algérien)

Caradocian graptolites have been recovered for the first time from several bore-holes in the Tinrhert region of the Algerian Sahara. Stratigraphically, they belong to the Oued Ahara upper Member of the Edjeleh Formation. The graptolites are assigned to the new sub-species Diplograptus foliaceus tinrherti that is briefly described. The occurrence of D. foliaceus (sensu lato), whose upper stratigraphic limit is Upper Soudleyan, indicates a probable Burrellian (Middle Caradocian) age for a more or less important part of the upper Oued Ahara Member. This is an additional age constraint for the beginning of the Late Ordovician glacial episode in the region, since the first glacial sediments (Gara Louki Formation) lie in erosional disconformity on the Oued Ahara Member.