Vessem Member NMRFV


Premise Member defined by van Adrichem Boogaert and Kouwe (1997). Introduced to accommodate the predominantly sandy sediments that make up the lower part of the Rupel Formation. The Vessem Member replaces the term Berg Sand Member NAM and RGD (1980) , but the concept of the two members differs. The Berg Sand Member was used to denote the basal transgressive sands of the Rupel Formation. The Vessem Member is not simply a transgressive unit, but includes several coarsening-upwards units that developed locally below the main transgressive surface. The member corresponds in the southern Netherlands with the sandy members of the Belgian Zelzate Formation and the Bilzen Formation (including the Berg Member) Marechal and Laga (1988) . In the eastern Netherlands it can be correlated with the Ratum Member of van den Bosch (1975) .
Derivatio nominis Named after the town of Vessem in the province of Noord-Brabant, close to the type well.
Type section Location map See figure (pdf)
  Well Veldhoven-1 (pdf)
  Location N 51°26'20.8
E 05°21'37.2
  Depth 1213 to 1229 m
  Length 16 m along hole
  Reference 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 1391 to 1410 m
  Length 19 m along hole
  Well Overflakkee-1 (pdf)
  Location N 51°46'24.5
E 04°02'13.8
  Depth 387 to 444 m
  Length 57 m along hole
Definition The member comprises the predominantly sandy deposits that constitute the lower part of the Rupel Formation. Over the major part of the Netherlands onshore area, the Vessem Member is developed as a simple transgressive unit consisting of silty to clayey sands with a low glauconite content; flint pebbles or phosphorite nodules commonly occur at the base. This is the equivalent of the Berg sands in Belgium (the Berg Member of the Bilzen Formation in Marechal and Laga (1988) . Calcareous fossils are generally absent. In a basin setting, the Vessem Member becomes a more heterogeneous unit. In the Voorne Trough (see pdf) and the Zuiderzee Low and locally in the eastern part of the Netherlands, only the topmost part is a thin transgressive sand layer. There, the member consists largely of stacked coarsening-upwards units. The sands of these units have a relatively high glauconite content and contain no pebbles. Autochthonous phosphorite nodules occur in some areas. The sands and the intercalated clays have a low carbonate content or are devoid of calcium carbonate.
Upper Boundary The upper boundary has been placed at the base of the clays of the overlying Rupel Clay Member.
Lower Boundary Wherever the Vessem Member is developed as a simple transgressive unit, it unconformably overlies the Dongen Formation or older sediments. In the Voorne Trough (see pdf) and the Zuiderzee Low, the lower boundary is ill-defined and a mild unconformity is presumed to be present between the Vessem Member and the Dongen Formation. In southern Limburg it mildly unconformably overlies the sediments of the Tongeren Formation.
Distribution The member is present in the southern half of the Netherlands and adjacent offshore area. It is absent on the Kijkduin High and at the northwestern flank of the Zuiderzee Low RGD (1983) .
Age Priabonian - Rupelian (NP 19/20- NP 23). The age varies geographically. In the areas of the Voorne Trough (see pdf) and the Zuiderzee Low, the age covers the interval NP 19/20 - lowermost NP 23. The Vessem Member becomes progressively younger towards the south and the east. In the southern part of Limburg, the age is NP 23.
Depositional Setting Over most of the area the Vessem Member is a transgressive shallow-marine sand. In southern Limburg a lagoonal clay is intercalated. Basinward of this clay, the presence of a coastal barrier facies is inferred. The coarsening-upward sequences below the main transgressive surface represent shallow-marine sands prograding onto middle- to outer-neritic clays. The base itself is presumed to be a transgressive, shallow-marine sand.
Sequence Stratigraphy The Vessem Member cannot be interpreted straightforwardly in terms of Haq (1988) 's sequences. According to its nannoplankton content, the Vessem Member represents the time interval covered by sequence TA 4.2, TA 4.3 and the low stand and early transgressive part of TA 4.4. But the architecture of the member only partially agrees with what could be expected on the basis of the Haq (1988) cycle chart. The sequence-stratigraphic position of the sediments with a NP 22 flora poses a problem. At many places these sediments are clearly coarsening upwards, suggesting that they represent the Lowstand systems tract of seuquence TA 4.4. Yet they are evidently transgressive, covering a much wider area than the deposits with a NP 21 flora. Presumably regional factors have been superimposed on a global signal. The lagoonal sediments in southern Limburg, known as the Kleine Spouwen Clay, are considered to represent a fourth-order cycle.
  In southern Limburg local names are in use for the lower part of the Rupel Formation (Kuyl (1975) ; Kuyl (1980) ; NAM and RGD (1980) ; RGD (1984b) ). These are from top to bottom:
  NMRFB Boom (Clay) Member
  NMRFN Waterval Member
    Kleine Spouwen Member
  NMRFS Berg Member
  The lower three units belong to the Vessem Member. The Kleine Spouwen Clay, also known from the Belgian Nomenclature of Marechal and Laga (1988) , is a brownish to bluish-grey, sandy clay, practically without glauconite, intercalated in the sands. The Berg Sands in this context equate the Berg Member of the Belgian nomenclature.
  In the Twente area, van den Berg and Gaemers (1993) have described the lower part of the Ratum Member (the local equivalent of the Vessem Member) as the Ootmarsum Sand. It consists of a highly glauconiferous, coarsening-upward sand unit, which is overlain by the remaining part of the Ratum Member consisting of a fining-upward succession of very fine-grained sands.
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].