Algal microfacies in the Theniet Et Temar Formation (middle Oxfordian), Central Saharan Atlas, Algeria

Abstract

During the Oxfordian, sea-level rise created widespread carbonate platform deposition on the margins of Neotethys, although some areas remain poorly described. One such area is the Saharan Atlas of Algeria. Accordingly, the middle Oxfordian Theniet Et-Temar Formation at a new locality, Kef El Meleh, is described for the first time. Formed of marl/limestone cycles, 6 broad microfacies are present within the limestones, representing deposition in lagoon, shoal and nearshore environments. Whilst overall shallowing-up is evident, it is unclear if the smaller scale marl–carbonate cycles represent higher frequency shallowing-up, or allocyclic depositional patterns.

The Theniet Et-Temar Formation contains an important archive of macrofossils and microfossils. Of note at Kef El Meleh is the presence of a microfacies rich in dasycladalean algae, notably Salpingoporella annulata Carozzi, 1953. The specimens conform well to the type and subsequent descriptions. The assemblage is effectively monospecific in terms of algae, although the larger foraminifera Alveosepta jaccardi (Schrodt, 1894) is present. This record extends the knowledge of the distribution of S. annulata within Neotethys, especially within the Oxfordian, for which previous records are limited in comparison to those for the later Jurassic and Early Cretaceous.