Lower Germanic Trias Group

RB

Formal (NAM & RGD 1980). Amended (Van Adrichem Boogaert & Kouwe 1994).

Red-bed-type sandstones, siltstones and claystones.

Lacustrine and fluvial setting with local aeolian influences.

Placed at the base of a thin, but distinct sandstone bed forming the basal unit of a gradual fining-upwards trend, which overlies the topmost claystones or carbonates of the Zechstein Group. On wireline logs, this sandstone bed commonly displays relatively low gamma-ray values and high acoustic velocities suggesting anhydrite cementation.

Formed by the unconformity at the base of the Upper Germanic Trias Group. It is placed at the base of the Basal Solling Sandstone Member, which is generally distinguished by higher acoustic velocities (indicating a higher degree of cementation) than the underlying sandstones.

Up to 3000 m.

UK: Bacton Group; GER: Bundsandstein Group; BEL: Lower Germanic Trias Group.

late Changhsingian - latest Olenekian.

The name has been derived from the German stratigraphic nomenclature, where it is commonly applied to denominate the entire sedimentary sequence between the Zechstein Group and the Jurassic claystones . The prefix ‘Lower’ applies to the part of the Germanic Trias which occurs below the Hardegsen Unconformity of Olenekian (late Scythian (Spathian)) age. In the present classification the lowest part of the claystone succession between highest Zechstein evaporite and the base of the ‘Upper Bröckelschiefer’ is assigned to the Zechstein (Zechstein Upper Claystone Formation).

The former Bunter Group (basin-margin development) of NAM and RGD (1980) is incorporated in the redefined Lower Germanic Trias Group. Detailed correlation permitted the identification of the formations of the basinal realm in the fringe area.

Johan ten Veen (2017).

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. 1994. Stratigraphic nomenclature of The Netherlands; revision and update by RGD and NOGEPA, Section E, Triassic. Mededelingen Rijks Geologische Dienst, 50, 1-28.