4.2.1 Wanne Formation - WAN (old: Rv1-2)

Author: after Geukens, 1999.

Description: Dark green-blue fine slate and green-greyish quartzite, alternating with dark slaty quartzite; some rare 10-15 cm thick conglomerate beds with slaty, quartzitic and sometimes phosphatic pebbles. The lower part comprises black silty slate (called “quartzophyllade” in the older literature), sometimes slate and black finely stratified quartzite. Some interstratified volcanic lavas or tuffs are present.

Stratotype: Not yet defined; type area in the outcrops of the Salm valley south of the village Trois Ponts.

Area: Stavelot Massif.

Thickness: 550-650 m.

Age: The presence of the inarticulate brachiopod Acrothele cf. bergeroni indicates a Mid Cambrian age (Vanguestaine & Rushton, 1979); the acritarchs belong to the biozones 1, 2 and 3, dated as Early (?) to Mid Cambrian (Vanguestaine, 1974, 1992; Vanguestaine & Van Looy, 1983).