Clay Deep Member SGLUC


Premise The member is defined by NAM & RGD in 1980 and amended by Herngreen & Wong (1989) and by Van Adrichem Boogaert & Kouwe (1993). The Clay Deep Member is transferred to the new Lutine Formation, Scruff Group (Munsterman et al., 2012). The Clay Deep Member was inappropriately classified in the Kimmeridge Clay Formation sensu Van Adrichem Boogaert & Kouwe (1993), in spite of its chrono- and lithostratigraphic distinction from that formation. The lithology also evidently differs. The member lacks the well-developed dolomite stringers seen in the Kimmeridge Clay Formation, and tends to show higher GR-log readings. Note that the interval of the reference well B18-02 is restricted to interval 2225-2315 m. The base interval 2315-2355 m is transferred to the Scruff Greensand Formation. Herngreen et al. (2000) showed that this low-GR section, in addition to the dating of ‘latest Middle Volgian-Late Volgian’ at 2343 m depth, can be associated with the Scruff Greensand Formation. The correlation to well B18-03 verifies this interpretation.
Derivatio nominis Named after the Clay Deep, a sea-bottom depression situated at approximately N 55°, E 04° in the Netherlands offshore.
Type section Location map See figure (pdf)
  Well B18-02 (pdf)
  Location N 54°05’35.4
E 04°47’48.6
  Depth 2225 to 2315m
  Length 90 m along hole
  Reference Munsterman et al. (2012)
Additional section Location map See figure (pdf)
  Well F03-01 (pdf)
  Location N 54°59’40.0
E 04°54’18.0
  Depth 2265 to 2335 m
  Length 70 m along hole
  Reference Van Adrichem Boogaert & Kouwe (1993), Annex G-3
Definition The member comprises (brownish-) grey to black claystones. The base of the Clay Deep Member is usually more silty. The claystones are generally rather bituminous, but locally less organic matter may be present.
Upper Boundary The upper boundary coincides with the Sequence 3 / Sequence 4 transition sensu Abbink et al. (2006; Figs 2 and 6). It is associated with the Late Kimmerian unconformity. The member is covered (sometimes virtually conformably) by the Rijnland Group (or the Chalk or Lower North Sea Group). The boundary is shown by upwards decreasing values on the GR and the resistivity logs. The lithology changes towards sandy claystone/marl or limestone.
Lower Boundary The Clay Deep Member rests unconformably on the undifferentiated Scruff Greensand Formation (block F03) or Kimmeridge Clay Formation. The bituminous shales of the Clay Deep Member can be distinguished easily from the main Kimmeridge Clay Formation by their higher GR- and resistivity-log response. The contact with the Scruff Greensand Formation below is clear because of the change in lithology.
Distribution The Clay Deep Member is restricted to the northern part of the Dutch Central Graben and Step Graben (blocks B18 to F08/F11). The organic matter content decreases to the south, where the Clay Deep Member grades into the Schill Grund Member. The lateral equivalents of the Clay Deep are the ‘Hot Unit’ of the Farsund Formation (Danish sector, Michelson & Wong, 1991) and the Mandal Formation (Norwegian sector of the Central Graben) (see pdf).
Age Sequence 3 sensu Abbink et al. (2006): Ryazanian. The base of the Clay Deep Member is diachronous. It has an Early Ryazanian age (runctoni Ammonite Zone) in the northernmost part of the Dutch Central Graben (e.g. in the B18 and F03 blocks) and a Late Ryazanian age in the south. Characteristic dinoflagellate species are Batioladinium radiculatum, B. cf. varigranosum, Dingodinium spinosum (LOD: Late Ryazanian, albidum Ammonite Zone), Egmontodinium polyplacophorum, Gochteodinia virgula (LOD: Early Ryazanian, runctoni Ammonite Zone), Rotosphaeropsis thula and Systematophora daveyi. The agglutinated foraminifer Haplophragmoides cf. infracalloviensisis is regularly recorded.
Depositional Setting The Clay Deep Member was deposited in a shelf environment. Basin circulation stagnated which resulted in dysoxic to anoxic basin-floor conditions and in the deposition of bituminous claystones.
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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