Niedersachsen Group SK

 

Premise Definition after NAM and RGD (1980) . This group contains floodplain, lake and (hypo- to hypersaline) lagoonal deposits, locally with a high content of carbonates and evaporites, restricted to the Lower Saxony Basin. A new code is introduced here for the group. The old ND-abbreviations can be mistakenly associated with the Noordzee groups of the Tertiary, which also have codes starting with an N. The code SK is adopted here. It has been used in-house by the RGD for many years. Important introductory papers to this group have been published by Schott (1951) and t Hart (1969) . The igneous Zuidwal Volcanic Formation, which was placed in this group in NAM and RGD (1980) , has been excluded. It has been be placed in a new, separate group of igneous rocks (XXZV, section 6.1).
Derivatio nominis Named after the German area of Niedersachsen (= Lower Saxony).
Type section Location map See figure (pdf)
  Well Schoonebeek-197 (pdf)
  Location N 52°38’58.0
E 07°02’34.2
  Depth 944 to 1590 m
  Length 646 m along hole
  Reference NAM and RGD (1980)
Additional section Location map See figure (pdf)
  Well Ruinen-1 (pdf)
  Location N 52°44’09.8
E 06°27’12.8
  Depth 994 to 1196 m
  Length 202 m along hole
  Well Exloo Odoorn-2 (pdf)
  Location N 52°54’20.7
E 06°51’57.8
  Depth 1644 to 1718 m
  Length 74 m along hole
  Well De Bente-1 (pdf)
  Location N 52°41’37.8
E 06°46’15.7
  Depth 1109.5 to 1344 m
  Length 234.5 m along hole
  Well Oldenzaal-2 (pdf)
  Location N 52°17’18.8
E 06°56’23.8
  Depth 114 to 588 m
  Length 474 m along hole
Definition Group of formations with a predominantly clayey lithology, but also including limestones and evaporites in the lower part. Sands and conglomerates are restricted to the basin fringe. Type well Schoonebeek-197 displays an exceptionally thick succession for Dutch standards. The additional reference sections display the more typical development in the Netherlands.
Upper Boundary The Niedersachsen group is unconformably overlain by the (sands or clays of the) Rijnland Group NAM and RGD (1980) .
Lower Boundary The group rests unconformably on the Altena Group (or older sediments)
Distribution Restricted to the Lower Saxony Basin, which reaches the easternmost parts of the Dutch provinces of Groningen, Drente and Overijssel. NAM and RGD (1980) also report the group in the Central Netherlands Basin and Vlieland Basin (see pdf) , but these occurrences are now placed in the Zurich Formation of the Schieland Group (Delfland Subgroup). The lithofacies of the Schieland Group (Zurich Formation) in the Central Netherlands and Vlieland Basin (see pdf) s resemble those of the Niedersachsen Group. An actual connection of the two realms is not proven, although some scattered occurrences which are tentatively assign-ed to the Zurich Formation on the Groningen High (RGD, in prep.), are very close to the Niedersachsen realm.
Age Middle Kimmeridgian-Ryazanian/?Early Valanginian NAM and RGD (1980) .
Depositional Setting Judging from the lithofacies associations and palaeontological associations, it was deposited in a fresh- to brack-ish-water lake basin with intermittent marine and hypersaline periods. Hypersaline sediments dominate the Weiteveen Formation
Sequence Stratigraphy The group represents several full sequences (Haq (1988) ’s sequences LZA 4.6 - LZB 1.6, possibly even part of LZB 2.1). Vertical lithofacies changes reflect the different systems tracts.
Subdivision  
  The Niedersachsen Group is subdivided into the:
  SK Niedersachsen Group
  SKCF Coevorden Formation
  SKWF Weiteveen Formation
References See References Upper Jurassic/ Lower Cretaceous

Van Adrichem Boogaert, H.A. & Kouwe, W.F.P., 1993-1997. [Stratigraphic unit]. In: Stratigraphic Nomenclature of the Netherlands.
Retrieved [Datum] from [url].