Rupel Clay Member NMRFC

 

Premise Originally defined by NAM and RGD (1980) as Boom Clay Member. Renamed to avoid confusion with the original notion of the ‘Boom Clay’, and to bring the nomenclature in line with that of the other dominant clay members in the Lower and Middle North Sea Group (e.g. Landen, Dongen and Veldhoven Clay members). The Boom Formation of the Belgian nomenclature Marechal and Laga (1988) covers only the part of the Rupel Clay Member that overlies the transgressive upper part of the Vessem Member.
Derivatio nominis Named after the river Rupel in Belgium.
Type section Location map See figure (pdf)
  Well Veldhoven-1 (pdf)
  Location N 51°26'20.9
E 05°21'27.2
  Depth 1122 to 1213 m
  Length 91 m along hole
  Reference (amended after NAM and RGD (1980) )
Additional section Location map See figure (pdf)
  Well Asten-1 (pdf)
  Location N 51°23'47.7
E 05°47'27.3
  Depth 1317 to 1391 m
  Length 74 m along hole
  Well Doornspijk-2 (pdf)
  Location N 52°24'36.2
E 05°46'15.6
  Depth 715 to 779 m
  Length 64 m along hole
  Reference NAM and RGD (1980)
Definition The member consists of clays that become more silty towards basis and top. It is rich in pyrite, contains hardly any glauconite and calcium carbonate tends to be concentrated in the septaria layers. The silt content does not only change towards the top and the bottom of the member. Detailed studies in the Boom Clay in Belgium initiated by Vandenberghe (1978) have shown that silt and clay layers alternate at a decimetre to metre scale. Moreover, the organic-matter content is highly variable and distinct bituminous layers are present. Large intervals are practically devoid of calcareous microfossils. In areas relatively close to the basin margin, the clay can be subdivided into three parts. The lower part of the clay is silty and has a blue-grey colour. Higher in the succession a great number of bituminous bands is intercalated and the colour of the clay changes to dark green-grey, dark-brown or even black. The dark clays, which stand out on gamma-ray logs, are overlain by green-grey to green clays that are more marly and slightly more silty.
Upper Boundary In the southeastern Netherlands the Rupel Clay Member is conformably overlain by the sandy deposits of the Steensel Member. Outside the area, where the sandy member is present, the distinction with the argillaceous formations is explained under Boundaries of the Rupel Formation itself.
Lower Boundary In the major part of the Netherlands the member conformably overlies the sandy Vessem Member. In places where the Vessem Member is absent, the distinction with the underlying argillaceous formations is explained under Boundaries of the Rupel Formation itself.
Distribution The Rupel Clay Member is present over most of the Netherlands on- and offshore area. It is absent in the extreme southwestern and southeastern parts of the country and locally in the northeast, and in a small part of the western offshore.
Age Rupelian and early Chattian (NP 22 - lower part NP 24), Basinward also including Priabonian (NP 19-21). The foraminiferal assemblages are characteristic of the FF-Zone. Depositional setting: The clays were deposited in a middle to outer neritic setting. The foraminiferal content suggests that anaerobic conditions intermittently prevailed at the sea bottom. The organic matter is considered to be land-derived (Vandenberghe (1978) ; Vandenberghe and van Echelpoel (1987) ). The rhythmic alternation of silts and clays has been interpreted as an expression of Milankovitch cyclicity van Echelpoel and Weedon (1990) .
Sequence Stratigraphy The Rupel Clay Member represents the time equivalent of the late transgressive part of sequence TA 4.4 to the late Highstand part of sequence TA 4.5 over most of the Netherlands onshore. Where the Rupel Formation is wholly argillaceous the Rupel Clay member may include the time equivalent of TA 4.3 or even TA 4.2 as well.
Subdivision  
  For the eastern Netherlands (Twente and Achterhoek area) a local subdivision of the Rupel Clay Member has been made by van den Bosch (1975) , further detailed by van den Bosch (1984) . van den Berg and Gaemers (1993) have adapted this lithostratigraphic nomenclature as follows:
  NMRF Rupel Formation
  NMRFW Winterswijk Member
  NMRFH Brinkheurne Member
    Woold Clay  
    Kotten Clay  
   
  The latter two are considered as subunits of the Brinkheurne Member in the nomenclatorial hierarchy. The division of the Rupel Clay Member into three parts, as described under Definition, corresponds with these units plus the Winterswijk Member
References See References Tertiary

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