Crinoids from the Ouarsenis Massif (Algeria) fill the Lower Cretaceous (Berriasian and Valanginian) gap of northern Africa

Abstract

The Ouarsenis Massif belongs to the Algerian Tell domain which is considered as the eastern part of the Maghrebian Tethys former margin. The Berriasian-Valanginian Oued Fodda Formation outcropping in the Kef Aïn El Hadjela section, at the foot of the great peak of the Ouarsenis Massif, is composed of marls and laminated and bioturbated limestone alternations. The marl facies reveals diverse microfauna, including crinoids. These latter are represented by: Isocrinida [isocrinids (Balanocrinus cf. gillieroni (de Loriol), Percevalicrinus aldingeri Klikushin, Isocrinus? lissajouxi (de Loriol)], Cyrtocrinida [cyrtocrinids (Phyllocrinus sp., Hemibrachiocrinus sp.)], and Roveacrinida [roveacrinids (Gen. indet. sp. indet.)]. All these, with exception of roveacrinids and phyllocrinids, are noted for the first time from Algeria and African continent (southern margin of Tethys in the Maghreb). Knowledge on Cretaceous crinoids formerly described from Algeria is presented. It is also shown that crinoid assemblage and associated invertebrates are typical for relatively shallow, distal depositional setting situated below storm wave base.