Arentigué Fm

Faure, 1966.

References: Furon, 1964; Faure, 1966; Fabre et al., 1983; Meister et al., 1994.

Synonym: Arentigue Fm, Zoo Baba-Arentigué formation; Equivalent(s): Zoo Baba Fm; Béréré Fm; Iguéllala Mountains Fm.

Fine sandstones, clays, and ferruginous levels are comparable to those of the Kafra Fm. Grey, pink to black fossils-rich limestones. Includes green gypsum-bearing shales. Its thickness is 70 to 250 m in the Bilma Sub-Basin. In the Téfidet Sub-Basin, the Zoo Baba Fm – Arentigué Fm, defined as the “Série Cénomanienne-Turonienne” by Faure (1959), is 60 m thick.

Ammonites (Fig. 1, Fig. 2), Lamellibranchs, Gastropods, oysters (Exogyra olisiponensis), and sea-urchins (Cidaris taouzensis). Even though Furon (1964) does not mention the name of the Formation literally, he does say for the same time interval in the area:

• Upper Cenomanian: clays and limestones with Neolobites.
• Lower Turonian: limestones with Nigericeras lamberti Schn., Veniella byzancenica Perv., Plicatula fourneli Coq., then limestones with Pseudotissotia (Bauchioceras) nigeriensis Wood, Granocardium productum Sow.

[Figure 1: Ammonites from the Arentigué Fm - Zoo Baba Fm in the Cheffadène area. 1 & 2) Neolobites vibrayeanus brancai. 3 to 7) Thomelites (?) tenerensis (Meister et al., 1994)]

[Figure 2: Location of the marine Upper Cretaceous ammonite-bearing outcrops of the Arentigué Fm - Zoo Baba Fm within the Bilma and Téfidet Sub-Basins (Source: Meister et al., 1994)]

Marine