Swalmen Member NLLFL


Premise Member defined by van Adrichem Boogaert and Kouwe (1997). In the NAM and RGD (1980) Nomenclature this unit was part of the Heers Sand Member. The new member corresponds with part of the Belgian Opglabbeek Formation Marechal and Laga (1988) . In older publications the Swalmen Member is often referred to as ‘Limnic Montien’ Pannekoek (1956) . During mapping in southern Limburg the unit has been referred to as the Lutterade Clay (Member) of the Maasmechelen Formation RGD (1983) . As the Maasmechelen Member of the Belgian Opglabbeek Formation clearly describes a different lithology (light grey to green-grey, argillaceous, calcareous sand), it is proposed to refrain from using this name here.
Derivatio nominis Named after the village of Swalmen in the province of Limburg, where the type well is located.
Type section Location map See figure (pdf)
  Well Swalmen LXXIII (pdf)
  Location N 51°14'07.9
E 06°03'32.6
  Depth 499 to 530 m
  Length 31 m along hole
Definition The major part of the member consists of an alternation of thin sand layers and humic clay layers, containing small pieces of coalified plant remains and locally, in its upper reaches, thin brown-coal beds. The sands have a yellowish grey-brown colour. The clay is hard and flaky, light to dark grey-brown to black, and contains pyrite nodules. The lower sandy layers locally contain shells and/or glauconite. Locally, very characteristic, bright red and olive-green spots and flames occur in the clays.
Upper Boundary The uppermost boundary is formed by the sharp lithologic transition to the glauconitic sands of the Heers Member.
Lower Boundary The lowermost boundary is characterised by an unconformity, expressed as a sharp lithologic and log break with the underlying Houthem Formation of the Chalk Group.
Distribution The member is known from the province of Limburg and the very eastern part of Noord-Brabant. It possibly occurs as well in southeastern Flevoland and the northern part of Gelderland.
Age Late Paleocene. The unit is characterised by a very low-diversity foraminiferal fauna, dominated by Nonion subleave. It does not contain nannofossils.
Depositional Setting Foraminifer and ostracod faunas indicate a brackish-marine to lagoonal environment. The brown-coal beds point to the occasional occurrence of paralic or limnic conditions.
Sequence Stratigraphy The unit was deposited during the very first local flooding of the transgressive phase overlying the Mesozoic and older deposits. It represents the first part of the Transgressive systems tract of cycle TA 2.1.
References See References Tertiary

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