Lower Buntsandstein Formation RBSH

 

Premise Definition amended afterNAM and RGD (1980) . The claystones between the highest Zechstein evaporite and the ‘Upper Bröckelschiefer’ are assigned to the Zechstein Upper Claystone Formation and part of the Bunter Group is incorporated in the Lower Buntsandstein Formation.
Derivatio nominis Name derived from the German stratigraphic nomenclature, where the Lower Triassic red beds are called ‘Buntsandstein’, subdivided into a Lower, Middle and Upper Buntsandstein. In the Dutch nomenclature the Lower Buntsandstein Formation constitutes the lowermost sedimentary cycle of the Triassic.
Type section Location map See figure (pdf)
  Well Blijham-1 (pdf)
  Location N 53°05’40.9
E 07°04’40.0
  Depth 2898 to 3255 m
  Length 357 m along hole
Additional section Location map See figure (pdf)
  Well Buurmalsen-1 (pdf)
  Location N 51°54’18.7
E 05°18’49.2
  Depth 1576 to 1973 m
  Length 397 m along hole
  Well Nederweert-1 (pdf)
  Location N 51°18’41.7
E 05°46’14.2
  Depth 2237 to 2572 m
  Length 335 m along hole
Definition Generally the formation is composed of a cyclical alternation of red-brown and green, in places grey, occasionally anhydritic claystones, siltstones and sandstones or calcareous oolite beds (‘Kleinzyklen’ of Röling (1991) ). These cycles can effectively be traced over large distances. The oolite beds occur predominantly in the upper part of the formation. In the southeastern part of the Netherlands coarse clastics, including conglomerates, predominate. The thickness of this formation is very uniform over extensive areas, ranging from 150 m in the West Netherlands Basin to 400 m in the Off Holland Low, Ems Low and Roer Valley Graben. There are indications for an increasing hiatus at its base towards the basin.
Upper Boundary The formation comprises the strata situated between the base of the first sandstone bed overlying the claystones of the Zechstein and the base of the massive sandstones in the basal part of the Volpriehausen Formation. In areas with a severe Base Solling truncation, the Lower Buntsandstein Formation may be unconformably overlain by the Solling Formation.
Lower Boundary A deviation from the definition of the formation by NAM and RGD (1980) is that the lowermost part of the former Basal Buntsandstein Member has been assigned to the Zechstein Group (Zechstein Upper Claystone Formation).
Distribution The formation is recognised in most parts of the onshore and offshore of the Netherlands. The formation is absent on the London-Brabant Massif, Texel-IJsselmeer High (see pdf) and Cleaver Bank High. This is mainly the result of the Late Kimmerian pulses of uplift and erosion.
Age Latest Permian - early Scythian.
Depositional Setting Most of the Lower Buntsandstein Formation was deposited in a lacustrine environment; in the Roer Valley Graben fluvial deposition prevailed. Typical for the formation is the wide-spread, small-scale depositional cyclicity and the great lateral and vertical uniformity. Red and green mottled intervals, anhydrite and carbonate nodules, various dewatering structures and desiccation cracks point to periodic flooding and drying in ephemeral lakes. Intercalated oolitic limestone beds indicate periods during which shallow lacustrine conditions with very little siliciclastic influx prevailed throughout the basin.
Subdivision  
  The basinal development of the Lower Buntsandstein Formation is usually subdivided into two members:
  RB Lower Germanic Trias Group
  RBSH Lower Buntsandstein Formation
  RBSHR Rogenstein Member
  RBSHM Main Claystone Member
  In the basin fringe area, a third member can be distinguished:
  RBSHN Nederweert Sandstone Member
  The Basal Buntsandstein Member, as formerly defined by NAM and RGD (1980) , has been dropped. Most of the unit is currently assigned to the (Zechstein Upper Claystone ).
References See References Triassic

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