2.3. OPGLABBEEK FORMATION - Op

Authors: De Geyter & Laga (1988b).

Description: a heterogeneous deposit, consisting of dark and reddish clay, small lignitic layers, plant remnants, shell-layers and fine sands, locally calcareous. In north-east Limburg a homogeneous sand complex (37 m thick) covers a more clayey entity, whereas in many boreholes only the clayey facies is found.

Stratotype: stratotypes have only been designated for the members.

Area: the northeastern part of Limburg, only in boreholes.

Members: the formation is subdivided into the Opoeteren Mbr and the Eisden Mbr.

Thickness: 25 m in the type area, 60 m in the Molenbeersel well.

Age: Early Selandian.

Remarks: the formation is named after the village of Opglabbeek where the Opoeteren and Eisden members are well represented in borehole 63W215 (KS19). The Maas-mechelen beds are considered a calcareous zone with the sandy Eisden Mbr. The formation is also discussed by Felder (1975), Felder et al. (1985), Halet (1932a), Maréchal (1993), Marlière (1968), Moorkens (1972a, 1972b, 1982), Schmitz & Stainier (1909), Stainier (1931), Steurbaut (1998) and Vincent (1930).