1999  Korn, p.149: Madène El Mrakib, 30 km SE of Fezzou, 80  km SSW of Erfoud, southern Ma'der. Mainly fine
           clastics, usually greenish claystones, with thin  intercalations of marly or calcareous nodular layers
           (text-fig.2). Monotonous succession of claystones with interbedded thin carbonates and black shales.
     2002  Becker et al., 181: UD 3-C1.