Obourg Chalk Formation

The information on this page is a summary description.
The full formal description is available here: Obourg Chalk Formation

Abbreviation OBG
Parent unit Chalk group
Child units
Lithological description A fine-grained white chalk, slightly greyer than the overlying Nouvelles Formation. In the northern part of the basin it contains a few dark black flints (used by Neolithic man for tool making, sometimes even exported towards the Meuse area). In the southern part of the basin chert nodules are absent or very small. A conglomerate layer may occur at the base of the formation containing phosphatised chalk pebbles, and numerous fossils, many of them reworked.
Age Early Late Campanian: cephalopods: Belemnitella mucronata, Patagiosites stobaei, Glyptoxoceras retrorsum, Baculites aquilaensis; brachiopods: Carneithyris carnea, “Cretirhynchia” octoplicata; echinoids:Echinocorys cf. ovata, E. gibba, Micraster schroederi, M. stolleyi; foraminifers: Bolivinoides decoratus, Gavelinella monterelensis, Stensioeina pommerana, Globorotalites michelinianus etc.
Thickness 15 to 25 m, more in boreholes.
Area of occurrence Mons Basin, in outcrops and quarries along the margins; also in boreholes.
Type locality No stratotype has been designated for the Obourg Formation. The Formation outcrops depending on quarrying activities at the C.C.C. and C.B.R. quarries at Harmignies (section in the C.C.C. quarry studied in Robaszynski & Christensen, 1989).
Alternative names
Authors Robaszynski, F., Dhondt, A.V. & Jagt, J.W.M.
Date 01/01/2001
Cite as Robaszynski, F., Dhondt, A.V. & Jagt, J.W.M., 2001. The Obourg Chalk Formation, 01/01/2001. National Commission for Stratigraphy Belgium. https://ncs.naturalsciences.be/lithostratigraphy/Obourg-Chalk-Formation
Additional information References: see Spiennes Fm.

Lithostratigraphy Cretaceous

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