2.9. Kiezeloöliet Formation - Kz

Authors: Doppert et al. (1975) after Fliegel and Stoller (1913).

Description: the formation consists of a wide variety of lithologies, all of fluvial and lacustrine origin. The lowest part consists of coarse grained sand, the Waubach Sand, the middle part predominantly of clay members often with lignitic horizons (the Brunssum II en Brunssum I Members) with a sand member in between (the Pey Member) and the upper part consists of fine to coarse grained sand with some clayey intercalations (the Jagersborg Member).

Stratotype: the type-section is in Germany (Fliegel & Stoller, 1913) in a former gravel pit at Duisdorf near Bonn. The type section for the Netherlands is the area of Waubach - Brunssum - Schinveld, where deposits are exposed in clay and gravel pits and have been studied in numerous wells.

Area: in Belgium, this formation name is only used for these deposits in the Roer valley graben, being the continuation of the Dutch part of the graben (Demyttenaere & Laga, 1988). The formation outcrops occur only northeast of the Feldbiss and Reppel faults (= the western limit of the Roer valley graben).

Thickness: up to 250 m

Members: the members are defined in the Netherlands (van Adrichem Boogaert & Kouwe, 1997) except the uppermost Jagersborg Member, approximately 45 m thick. Part of this member may be of Quaternary age (Sels, Claes & Gullentops, 2001)

Age: Tortonian, Messinian, Zanclean, Piacenzian