Oligocene of Belgium.
(Rupelian, Base Boom Clay)
The Belgian Oligocene is
dominated by the early Oligocene, late Rupelian Boom
Clay Formation (R2c), exposed
in several quarries. Maurice Leriche
(1910) made a great work about the sharks and rays of the Boom
clay, figuring extraordinary specimens and some unique associated tooth
sets. This large formation is deposited in relatively deep water and is divided
in 69 layers. The Boom clay quarries are widespread, but the vertebrate remains
are not. Some layers proved to be little better than others: layers 49, 41
Numerous phosphatic nodules and some shark remains are present at the base
of this Boom Clay. This exceptional early Rupelian
phosphate bed (circa 32Ma) is covering the fine, glauconitic Ruisbroek Sands
of the Zelzate Formation. The stratigraphic age of this formation is at the
Eocene-Oligocene transition. Hard work is needed to access and sample this horizon; Carcharias acutissima
(Agassiz, 1843) and Physogaleus latus (Storms, 1894) are by far the
most commonly found shark species.
In 1991 and 1992, when widening the Albert canal in Gellik near Lanaken, also
the sandy part of the Belgian Rupelian could be sampled. These sediments are
dated early Rupelian in age and are belonging to the Bilzen Formation, Member
of Kerniel (R1d). This (sandy) locality shares the same fauna diversity as
the rest of the (mostly clayish) Belgian Rupelian.
BAUT, J.P. & GENAULT, B., 1999. Les elasmobranches des Sables
de Kerniel (Rupélien), à Gellik, Nord est de la Belgique.
Memoirs of the Geological Survey of Belgium, 45.
LERICHE, M., 1910. Les Poissons Oligocènes de la Belgique. Mémoire
du Musée Royal d'Histoire Naturelle de Belgique, 363 pp.
2007. A new species of Abdounia (Elasmobranchii, Carcharhinidae) from
the base of the Boom Clay Formation (Oligocene) in northwest Belgium.
Geologica Belgica, 10(1-2): 69-77.
STEURBAUT, E. & HERMAN, J., 1978. Biostratigraphie
et poissons fossiles de la formation de l'argile de Boom (Oligocène
moyen du bassin belge). Géobios 11/3.
VANDENBERGHE, N., HERMAN, J. & STEURBAUT, E., 2002. Detailed analysis of the Rupelian Ru-1 transgressive surface in the type area (Belgium). In Gürs, K. (ed.), Northern European Cenozoic Stratigraphy. Proceedings of the 8th Biannual Meeting of the RCNNS/ RCPNS, 67-81. Landesamt für Natur und Umwelt des Landes Schleswig-Holstein, Flintbek.
© P. De Schutter - 2006