Silverpit Formation ROCL

 

Premise Defined by Rhys (1974) . Adopted for the Netherlands by van Adrichem Boogaert (1976) .
Derivatio nominis Named after the Outer Silver Pit, an offshore deep in the British sector of the North Sea.
Type section Location map See figure (pdf)
  Well K06-01 (pdf)
  Location N 53°48’58.9
E 03°59’03.5
  Depth 3308 to 3634.5 m
  Length 326.5 m along hole
  Reference (amended after NAM and RGD (1980) )
Additional section Location map See figure (pdf)
  Well Slochteren-4 (pdf)
  Location N 53°11’33.2
E 06°45’14.9
  Depth 2666 to 2709 m
  Length 43 m along hole
  Reference NAM and RGD (1980)
  Well Uithuizermeeden-1 (pdf)
  Location N 53°26’58.9
E 06°48’29.2
  Depth 2875 to 2949 m
  Length 74 m along hole
  Depth 3041 to 3058 m
  Length 17 m along hole
Definition Sequence of red-brown, silty, often anhydritic claystones with some sand- or siltstone stringers and thin beds, and with rock-salt intercalations in the centre of the basin. Bedding structures can be massive, laminated or rippled, locally with abundant cracks, fluidisation phenomena and/or evaporite nodules. Intercalated sandstone beds are frequently reddish, graded, cross-bedded, and may contain clay pebbles. Some sandstone beds are light-coloured, free of clay matrix, laminated or cross-bedded.
Upper Boundary The formation is overlain by the black bituminous shales of the Coppershale Member of the Z 1 (Werra) Formation.
Lower Boundary The formation unconformably overlies the Limburg Group (or possibly locally the volcanics of the Lower Rotliegend Group), or conformably covers the sandstone-conglomerate sequence of the Slochteren Formation.
Correlation Towards the margins of the basin intertonguing of the Slochteren Formation and the Silverpit Formation occurs.
Distribution The formation is encountered in almost the entire Dutch sector of the Southern Permian Basin, with the exception of the southern part. The maximum thickness is found in the eastern offshore. Three claystone members extend into the transition zone between the basin and the fringe developments. The Ameland Member extends much further south than the Hollum Member. The Ten Boer Member in turn protrudes further than the Ameland Member, over most of the transition zone.
Age Saxonian. According to recent studies Menning (1994) , this middle-European age is most likely part of the Late Permian (Tatarian). Deposition was initially mainly restricted to the basin centre, but the area, in which the Silverpit Formation was laid down, progressively expanded southwards across the transition zone.
Depositional Setting The Silverpit Formation consists mainly of water-laid deposits, although indications of subaerial exposure have been encountered (mudcracks, evaporite nodules). Depositional environments recognised in the formation consist predominantly of lake (rippled or massive claystones) and playa-lake (massive evaporite beds and claystones) settings in the centre of the basin. In the transition zone, sabkha deposits (rippled, adhesion-rippled, mudcracked or convoluted claystones and argillaceous sand- and siltstones) predominate, with intercalations of distal fluvial-plain (graded, cross-bedded, pebbly sands) and aeolian sandflat (laminated or cross-bedded, matrix-free sands) deposits.
Subdivision  
  In the transition zone, four members can be recognised in the Silverpit Formation. The recognition of these member depends on their stratigraphic position relative to certain prominent tongues of the Slochteren Formation. The most common subdivision in that zone is shown below:
  RO Upper Rotliegend Group
  ROCL Silverpit Formation
  ROCLT Ten Boer Member
  ROCLA Ameland Member
  ROCLH Hollum Member
  In the Ameland-Terschelling area the Lower Slochteren Member extends less far into the centre of the basin than the Upper Slochteren Member. Here, the Upper Slochteren Member overlies a thick succession of the Silverpit Formation, embracing the equivalents of the Hollum and Ameland Members, and the lateral equivalent of the Lower Slochteren Member. This interval is named the:
  ROCLB Buren Member
  In the basin centre, a three-fold subdivision is applied for the Silverpit Formation.
  ROCLU Upper Silverpit Claystone Member
  ROCLE Silverpit Evaporite Member
  ROCLL Lower Silverpit Claystone Member
  The recognition of these members depends on the occurrence of evaporite beds in the succession.
References See References Permian

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