Scruff Greensand Formation SGGS

 

Premise The formation is included in the Scruff Group.The formation was defined by Herngreen & Wong (1989) and amended by Van Adrichem Boogaert & Kouwe (1993; Fig. 1). Here, the formation is amended to comprise all shallow marine glauconitic sandstones of the Central Graben, Schill Grund Platform, Step Graben, Terschelling and Vlieland basins in Sequence 3 sensu Abbink et al. (2006). Two members are recognised in the Scruff Greensand Formation: the Scruff Spiculite and Stortemelk members. The Scruff Basal Sandstone and Scruff Argillaceous Members are abandoned. The sandy part of the Scruff Argillaceous Member and the Scruff Basal Sandstone are integrated in the new Noordvaarder Member. The Noordvaarder Member is classified in the Skylge Formation, which is part of Sequence 2.
Derivatio nominis Named after the offshore Upper Scruff Bank in the North Sea near well F03-03.
Type section Location map See figure (pdf)
  Well F15-02-S1 (pdf)
  Location N 54°14’18.5
E 04°50’44.9
  Depth 3021 to 3065 m
  Length 44 m along hole
  Reference Munsterman et al. (2012)
Additional section Location map See figure (pdf)
  Well F18-01 (pdf)
  Location N 54°05’54.5
E 04°44’32.1
  Depth 2175 to 2230m
  Length 55 m along hole
  Reference Munsterman et al. (2012)
Definition The formation consists of grey-green shallow marine fine-grained sandstones that are often intensely bioturbated. The glauconite content is generally high and locally spiculites are abundant at the base of the section. The sandstones may be slightly argillaceous and/or calcareous.
Upper Boundary The Scruff Greensand Formation is generally conformably overlain by the Lutine Formation. The contact is diachronous. In the northernmost part of the Central Graben the base of the Lutine Formation is older. This upper contact is marked by a general rise in GR-log readings. In the southern Dutch Central Graben an unconformable upper contact with the Vlieland Claystone Formation (Rijnland Group) may locally be present.
Lower Boundary The Scruff Greensand / Skylge Formation transition is associated with the Sequence 2 / Sequence 3 boundary sensu Abbink et al. (2006). Sequences 2 and 3 are relatively thick in the Terschelling Basin as compared to the Central Graben. A hiatus occurs in the Central Graben, but deposition was continuous in the depocentre of the Terschelling Basin (Abbink et al., 2006). The lower boundary with the Skylge Formation is marked by an increase in GR-log readings, resulting from the downward increasing clay content. The occurrence of the sponge spiculae at the base of the Scruff Greensand Formation may locally be taken as an additional criterion.
Distribution The Scruff Greensand Formation is present in, although not continuously, the Central Graben, Schill Grund Platform, Step Graben and Terschelling Basin, blocks A12-A15, B18 to M07. In the northern part of the Dutch Central Graben the formation occurs over the salt dome of the F03-FA field, where it forms a gas reservoir. Well-developed sands are absent in the central part of the Dutch Central Graben but local sandy sections have been observed along the margins of the basin (e.g. F11-03 and F12-03). In the L12 and L15 blocks the formation interfingers with the paralic Zurich Formation, into which it shales out (see pdf).
Age Sequence 3 sensu Abbink et al. (2006): latest Middle Volgian - earliest Late Ryazanian, oppressus-icenii Ammonite zones. The age of the top of the formation is diachronous. In the southern part of the Central Graben and the Terschelling Basin the top of the Scruff Greensand Formation has an earliest Late Ryazanian age (icenii Ammonite Zone), while in the northernmost part of the Central Graben the youngest occurrence reaches the Late Volgian.
Depositional Setting Shallow marine, shoreface to offshore environment.
Subdivision Two members are differentiated:
  SG Scruff Group
  SGGS Scruff Greensand Formation
  SGGSS Stortemelk Member
  SGGSP Scruff Spiculite Member
References See References Upper Jurassic/ Lower Cretaceous
D.K. Munsterman, R.M.C.H. Verreussel, H.F. Mijnlieff, N. Witmans, S. Kerstholt-Boegehold & O.A, Abbink (2012), Revision and update of the Callovian-Ryazanian Stratigraphic Nomenclature in the northern Dutch Offshore, i.e. Central Graben Subgroup and Scruff Group. Netherlands Journal of Geosciences-Geologie en Mijnbouw, 91 (4):555-590.
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