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4.2.12. Evieux Formation - EVX

Authors: Mourlon, 1875; Thorez et al., 1977.
Description: The Evieux Fm (former names: Evieux “assise”, or Evieux “psammites”) consists of a complex of shales and argillaceous, sometimes very micaceous sandstones, with towards the top, subordinate carbonate sandstones often decalcified.  Plant debris are very abundant.  The Evieux Fm was subdived by Thorez et al. (1977) into three members, from bottom to top:
1.     the Royseux Mbr, with arenaceous red beds, related to sabkhas, interlayered with supratidal evaporitic dolomites;
2.     the Fontin Mbr, with dolomites containing sublagoonal ostracods and oncolithic micrites;
3.     and the Crupet Mbr, with “continental” red beds.
Area: Namur and Dinant synclinoria, Vesdre Nappe, Theux Window.
Thickness: 120-200 m in the Dinant Synclinorium (200 m in the Ourthe valley).
Age: Upper (Fa2c) to Uppermost (Fa2d) Famennian. Upper P. styriacus, lower to middle Bispathodus costatus, and P. expansa conodont zones.