Helm Member SLDBH

 

Premise Member defined by van Adrichem Boogaert & Kouwe (1993). This member is closely associated with the Vlieland Sandstone Formation. It is situated above the Late Kimmerian II unconformity seismic reflector. It is intercalated between the Kotter and Helder Members of the Vlieland Sandstone Formation Its lithofacies, however, cannot be discriminated from the rest of the Breeveertien Formation
Derivatio nominis Named after the Helm oil field, block Q01, Dutch offshore sector.
Type section Location map See figure (pdf)
  Well Q01-03 (pdf)
  Location N 52°52’00.2
E 4°08’33.4
  Depth 1347 to 1379 m
  Length 32 m along hole
Additional section Location map See figure (pdf)
  Well P03-02 (pdf)
  Location N 52°58’32.2
E 3°59’57.7
  Depth 1815 to 1966 m
  Length 151 m along hole
Definition Silt- to claystone, light- to dark-grey and light-brown coloured, with abundant carbonaceous laminae which often show pyritised burrows, and with thin sandstone beds (mostly less than 1 metre). The clear sands have fine to medium, subangular to rounded grains. Minor occurrences of medium- to dark-grey claystone and white to light-brown limestone and dolomite are present. Lignite is locally abundant. In some wells (P03-02), abundant fragments of bivalves and gastropods have been encountered.
Upper Boundary The Helm Member is overlain by the sandy Helder Member of the Vlieland Sandstone Formation The range tops of Cantulodinium speciosum and Tubotube-rella apatela coincide with the boundary between the Helm and Helder Members in large parts of the Broad Fourteens Basin. In Q01 the Helm Member becomes younger (Late Valanginian, Gochteodinia villosa multifurcata Zone).
Lower Boundary The base of the Helm Member is marked by the acme top of Cantulodinium speciosum, which is considered to correlate with the top of the Ryazanian.
Distribution The occurrence of the Helm Member is restricted to the southwestern Broad Fourteens Basin (P03-Q01). The Helm Member interfingers with the Kotter Member of the Vlieland Sandstone Formation In the area of blocks K18 and P03 the Helm Member laterally, grades into the Kotter Member. Interfingering is seen in well K18-05. At the basin margins (going from Q01 into L16) the Helm Member is positioned laterally of the Helder Member.
Age A latest Ryazanian to Early Valanginian age is inferred from biostratigraphical data (mainly palynomorphs) and falls in the albidum Standard Ammonite Zone (Egmonto-dinium torynum dinoflagellate Zone). Towards the south-east (Q01) the member can become as young as Late Valanginian.
Depositional Setting The Helm Member is deposited in a marginal-marine setting at the landward (backbarrier) position of the beach-barrier strand-plain deposits of the sandy Kotter and Helder Members. Abundant gastropod fragments indi-cate restricted conditions in a lagoonal setting with thin wash-over sands developed during storms.
Sequence Stratigraphy Sequence LZB 2.1, at the basin margin also LZB 2.2. The lithofacies and distribution suggest an association with the later Transgressive to Late Highstand systems tract.
References See References Upper Jurassic/ Lower Cretaceous

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