4.1.2 Bellevaux Formation - BEL (old: Dvb)

Author: after Geukens, 1999.

Description: Alternation of greenish and purple slate and shale; greenish shale and white quartzite.

Stratotype: Amblève valley east of the city of Stavelot and in the Salm valley north of Rochelinval.

Area: In two anticlinal structures (Grand-Halleux and Ligneuville) in the southern part of the Stavelot Massif.

Thickness: 150 m.

Age: The only fossils present are the trace fossils Oldhamia antiqua and O. radiata. Because the genus Oldhamia is present in the Lower and Middle Cambrian only and not below the new GSSP of the Cambrian-Precambrian boundary (Crimes, 1992), an Early Cambrian age was proposed by Verniers and De Vos (1995). According to new observations by A. Seilacher (pers. comm., 1998) Oldhamia is more restricted in time and only present in the Tommotian or Nemakitian-Daldynian (early Early Cambrian), which would be the age of the formation. Acritarchs are recorded in the uppermost part of the formation, above the Oldhamia occurrences. They are assigned to the Zone 0 (Vanguestaine, 1974) indicating a mid or late Early Cambrian to early Mid Cambrian age (Vanguestaine, 1974, 1992).