Lower Graben Formation

SLCL

Formal (NAM & RGD 1980). Amended (Herngreen & Wong 1989; Van Adrichem Boogaert & Kouwe 1993).

Greyish brown, very fine to fine-grained, well-sorted sandstones, occurring in beds generally less than 10 m thick, with intercalations of thin greyish brown silty to sandy claystones. Generally carbonaceous with some distinct coal layers. Sandstone bodies have a rather restricted lateral extent. Coarsening-upward is observed in the upper parts.

Fluvial to delta- and coastal plain.

Disconformably overlies the Lower - Middle Jurassic formations, or formations from the Upper Germanic Triassic Group. Occasionally, the underlying Werkendam Formation may be developed in a coarse-grained oolitic facies, which makes the boundary between the two formations difficult to pick on logs alone.

Conformable and formed by the base of the Middle Graben Formation. This boundary is defined at the first distinct coal-bed recognised over most of the area.

Generally less than 260 m, but up to 560 m in block F03.

UK: Humber Group; GER: ?; BEL: -.

middle Callovian - late Callovian.

Named after the Central Graben.

None.

Sander Houben (2017).

NAM & RGD 1980. Stratigraphic nomenclature of The Netherlands. Verhandelingen van het Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap 32, 77 p.

Herngreen, G.F.W. and Wong, Th.E. 1989. Revision of the ’Late Jurassic’ stratigraphy of the Dutch Central North Sea Graben - Geol. en Mijnbouw, 68, p. 73-105.

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..