Code
NL
Status
Formal (NAM & RGD 1980). Amended (Van Adrichem Boogaert & Kouwe 1997). The NU-Group, NM-Group and NL-Group can be taken together as North Sea Supergroup (code N).
Lithological description
A group of formations consisting of an alternation of grey sands, sandstones and clays. They are the result of several small and large-scale, clastic sedimentation cycles in a marine realm along the edge of the North Sea Basin.
Depositional setting
Predominantly marine. An exception is the Swalmen Member, deposited in a lagoonal, brackish to non-marine environment.
Definition of lower boundary
In large parts of the onshore area, the lower boundary is characterised by an unconformity, expressed as a sharp lithologic break marking the top of the Chalk Group. Elsewhere, the group rests with a distinct unconformity on still older deposits.
Definition of upper boundary
The upper boundary is characterised by unconformably overlying deposits of the Middle North Sea Group or younger units.
Thickness indication
Up to ~650 m.
Geographical distribution
Regional correlation
UK: Montrose Group, Moray Group, Stronsay Group; GER: ?; BEL: ?
Age
middle Paleocene - middle Eocene (Selandian to Bartonian).
Holostratotype
Well:
Depth (thickness) AH:
691 - 1063 m AH (372 m)
Parastratotype
Well:
Depth (thickness) AH:
1007 - 1583 m AH (576 m)
Origin of name
Named after the North Sea. The prefix ‘Lower’ has been added to designate the lower part of the clastic sedimentary succession directly overlying the Chalk Group.
Previous name(s)
None.
Reviewed by (date)
Geert-Jan Vis (2019).
References
NAM & RGD 1980. Stratigraphic nomenclature of The Netherlands. Verhandelingen van het Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap 32, 77 p.
Van Adrichem Boogaert, H.A. & Kouwe, W.F.P. 1997. Stratigraphic nomenclature of The Netherlands, revision and update by RGD and NOGEPA, Section I, Tertiary. Mededelingen Rijks Geologische Dienst, 50, 1-39.
Cite as
TNO-GDN ([YEAR]). Lower North Sea Group. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from http://acc.dinoloket.nl/en/stratigraphic-nomenclature/lower-north-sea-group.