Formal (NAM & RGD 1980). Amended (Van Adrichem Boogaert & Kouwe 1993).
Section of grey, calcareous, occasionally sandy claystones. Limestone beds occur frequently in the basal parts, but disappear upwards, where the clays are less calcareous ('t Hart 1969) . In type well Schoonebeek-197 some halite beds occur in the base.
Marginal- to open-lacustrine setting with rare brackish influence. Fines settled from suspension. The carbonates (microcoquina shell beds) are interpreted as storm layers or periods of low sediment input (hardgrounds). Some fine sand was imported by small-scale fluvial/deltaic systems.
Definition of lower boundary
Clear claystone break, which is seen prominently on resistivity and sonic logs. In some salt-dome-related occurrences the Weiteveen Formation is absent, and the Coevorden Formation is in unconformable contact with the Altena Group or older deposits.
Definition of upper boundary
Fairly sharp increase in carbonate content. This generally coincides with the base of a funnel-shaped zone of increased resistivity-log readings. If the Middle Coevorden Member has been truncated, the Rijnland Group or younger deposits can overlay this member.
UK: ?; GER: Bückeberg Formation (Wealden); BEL: -.
Origin of name
Named after the town of Coevorden in the southeastern part of the Dutch province of Drente.
Lower Coevorden Clay member.
‘t Hart, B.B. 1969. Die Oberjura- und Unterkreide-Sedimentation in den nördlichen und östlichen Niederlanden - Erdöl und Kohle, Erdgas, Petrochemie, 22, p. 253-261.
NAM & RGD 1980. Stratigraphic nomenclature of The Netherlands. Verhandelingen van het Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap 32, 77 p.
Van Adrichem Boogaert, H.A. & Kouwe, W.F.P. 1993. Stratigraphic nomenclature of The Netherlands; revision and update by RGD and NOGEPA, Section G, Upper Jurassic and Lower Cretaceous. Mededelingen Rijks Geologische Dienst, 50, 1-80..
TNO-GDN ([YEAR]). Lower Coevorden Member. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from http://www.dinoloket.nl/en/stratigraphic-nomenclature/lower-coevorden-member.