The Ieper Group contains marine sediments which consist dominantly of clay in the lower part of the Group and become silty towards the top of the middle part and evolve to fine sandy sediments in the upper part of the Group.
Age
The Ieper Group almost coincides with the Ypresian or early Eocene age. Only the Tienen Formation of the Landen Group, below the Ieper Group, represents the very earliest Ypresian and the basal part of the Zenne Group above represents the very late Ypresian. Therefore the age of the Ieper Group can be estimated between about 55 and 49 Ma (see Vandenberghe et al. 2012 in GTS 2012).
Thickness
The maximal thickness is about 200m and thinning occurs towards the south and the east.
Area of occurrence
The Ieper Group occurs in the western, central and northern part of Belgium. The Group outcrops are located especially in northern Hainaut, south and central West and East Flanders, west and southwest of Brabant; the Group occurs in the subsurface of the Antwerp and Limburg Campine. Outliers occur in the Mons basin south of the Sambre river. Towards the east in the Brabant, Limburg and Antwerp provinces, the Ieper Group thins and disappears. Maps of the different Formations in the Ieper Group, recognised at different moments in the development of the Ieper Group stratigraphic research and practice, can be found in Maréchal (1993), (Walstra et al., 2014) and can be consulted at the D.O.V. website: https://dov.vlaanderen.be.
Type locality
The lower boundary stratotype is defined in Steurbaut (1998) at 288m depth in the Knokke borehole (011E0138) at the contact between the Tienen Formation (Oosthoek Member) and the Kortrijk Formation (Zoute Member), topographic map sheet 5/6 Westkapelle with coordinates X = 78.776, Y = 226.370, Z = +4,91 m. The upper boundary stratotype is defined in Steurbaut (1998) in the profile of the Mont-des‐Récollets (Cassel, France) at the contact of the Vlierzele Member and the Aalter Formation of the Zenne Group described in Nolf & Steurbaut, 1990, mapsheet XXIII‐3, Cassel, France with coordinates X = 62.000, Y = 344.500, Z = +143 m.
Alternative names
Authors
Steurbaut, E., De Ceukelaire, M., Lanckacker, T., Matthijs, J., Stassen, P., Van Baelen, H. & Vandenberghe, N.
Date
09/01/2017
Cite as
Steurbaut, E., De Ceukelaire, M., Lanckacker, T., Matthijs, J., Stassen, P., Van Baelen, H. & Vandenberghe, N., 2017. The Ieper Group, 09/01/2017. National Commission for Stratigraphy Belgium. http://ncs.naturalsciences.be/lithostratigraphy/Ieper-Group
