Lower Germanic Trias Group

Code
RB
Status
Formal (NAM & RGD 1980). Amended (Van Adrichem Boogaert & Kouwe 1994).
Lithological description

Red-bed-type sandstones, siltstones and claystones.

Depositional setting

Lacustrine and fluvial setting with local aeolian influences.

Definition of lower boundary

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.

Definition of upper boundary

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.

Thickness indication
Up to 3000 m.
Geographical distribution
Regional correlation
UK: Bacton Group; GER: Bundsandstein Group; BEL: Lower Germanic Trias Group.
Age
late Changhsingian - latest Olenekian.
Holostratotype
Depth (thickness) AH:
2736 - 3255 m (519 m)
Origin of name
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).
Previous name(s)
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.
Reviewed by (date)
Johan ten Veen (2017).
References
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.
Cite as
TNO-GSN ([YEAR]). Lower Germanic Trias Group. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from http://www.dinoloket.nl/en/stratigraphic-nomenclature/lower-germanic-trias-group.