Muschelkalk Formation RNMU

 

Premise This unit was first described in the Netherlands by van Waterschoot van der Gracht (1909) and formally introduced by NAM and RGD (1980) .The lower part of the formation is exposed in a quarry in eastern Gelderland, near Winterswijk.
Derivatio nominis Name derived from the German stratigraphic nomenclature, where it is applied to the middle, predominantly marine, part of the German Triassic.
Type section Location map See figure (pdf)
  Well Sleen-4 (pdf)
  Location N 52°48’30.3
E 06°50’14.9
  Depth 1376 to 1601 m
  Length 225 m along hole
  Reference NAM and RGD (1980)
Additional section Location map See figure (pdf)
  Well L02-01 (pdf)
  Location N 53°57’14.0
E 04°30’47.0
  Depth 3368 to 3650 m
  Length 282 m along hole
  Reference NAM and RGD (1980)
  Well Nederweert-1 (pdf)
  Location N 51°18’41.7
E 05°46’14.2
  Depth 1656 to 1870 m
  Length 214 m along hole
Definition Sequence of grey and variegated marls, argillaceous dolomites and limestones, anhydritic claystones, anhydrite and rock salt.
Upper Boundary The Muschelkalk Formation comprises the strata between the red-brown, silty claystones, evaporites and sandstones of the Röt Formation and the variegated, silty claystones of the Keuper Formation.The upper boundary is placed at the base of the lowermost claystone bed of the Keuper Formation, which is marked by a sharp decrease in acoustic velocity. In the eastern onshore the formation may be overlain unconformably by the Sleen Formation of the Altena Group. In the West Netherlands Basin the uppermost part of the Keuper Formation may rest unconformably on the Muschelkalk Formation.
Lower Boundary The lower boundary is picked at the base of the first distinct limestone or dolomite bed.
Distribution The formation is present in the Mesozoic basins and in parts of some adjacent platform areas. Erosion following the Late Kimmerian uplift removed deposits of the Muschelkalk from most platforms and highs. In the basin-fringe area the uppermost members of the Muschelkalk Formation are frequently missing, owing to intra-Keuper erosion.
Age Late Anisian - Early Ladinian. Samples from the lowermost Muschelkalk in the eastern Netherlands revealed a late Anisian age (Visscher (1966) Visscher and Commisaris (1968) ; RGD, 1993).
Depositional Setting The Muschelkalk was deposited in a shallow-marine to open-marine setting, where a temporary period of restricted conditions resulted in an evaporitic episode.
Subdivision  
  Following the German usage, the Muschelkalk Formation has been subdivided into a Lower, Middle and Upper Muschelkalk. Since the Middle Muschelkalk can be subdivided further into an evaporitic and marly part, four members are recognised:
  RN Germanic Trias Group
  RNMU Muschelkalk Formation
  RNMUU Upper Muschelkalk Member
  RNMUA Middle Muschelkalk Marl Member
  RNMUE Muschelkalk Evaporite Member
  RNMUL Lower Muschelkalk Member
  Where the boundary between the Middle Muschelkalk Marl Member and the Upper Muschelkalk Member tends to become obscure, e.g. in the southern onshore and the western offshore, as a result of a decrease in carbonate content of the latter member, the upper two members can be lumped into a larger unit, informally called the Muschelkalk Claystone member (). This situation occurs for example in well L02-01, interval 3368-3443 m below rt.
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].