Zurich Formation SLDZ


. upper Zurich Member lower Zurich Member
Premise Formation defined by van Adrichem Boogaert & Kouwe (1993). These deposits, restricted to the Vlieland Basin (see pdf) and Central Netherlands Basin, were previously placed in the Niedersachsen Group (’Wealden’ facies, NAM and RGD (1980) ) because of the frequent occurrence of intercalated carbonate and coal beds. The Zurich Formation equates to the Delfland Formation as described from the Vlieland Basin (see pdf) by Herngreen, Smit and Wong (1991) . Wire-line logs of all onshore wells mentioned in the text are depicted in that paper.
Derivatio nominis Named after the village Zurich near the coast of the province of Friesland.
Type section Location map See figure (pdf)
  Well Zurich Waddenzee-1 (pdf)
  Location N 53°07’25.7
E 05°20’39.1
  Depth 1773 to 2054 m
  Length 281 m along hole
  Reference The boundary between the upper and lower beds in this well is placed at 1905 m
Additional section Location map See figure (pdf)
  Well L15-FA-101 (pdf)
  Location N 53°19’48.7
E 04°49’56.1
  Depth 2504 to 2512 m
  Length 8 m along hole
  Depth 2504 to 2591 m
  Length 87 m along hole
  Reference originally L15-02
Definition Predominantly fine-grained interval of varicoloured or grey, sandy to silty mudstones with thin intercalated sand, carbonate (predominantly dolomite) and coal beds, occasionally fossiliferous and/or sideritic. In the Vlieland Basin (see pdf) the formation can be subdivided into two informal members. The lower member predominantly consists of mudstones with relatively frequent carbonate, predominantly dolomite, bands. The lime-stone beds intercalated in this interval resemble those of the Serpulite Member of the Weiteveen Formation in facies. The upper member consists of mudstones with frequent coal bed intercalations. Intercalated carbonate beds are rarely encountered. In the Central Netherlands Basin, the formation appears to be slightly sandier, but also devel-oped in a more calcareous lower part and a coaly upper part.
Upper Boundary The top of the lower member can be the conformable contact with the upper member, (e.g. Zurich Waddenzee-1); Scruff Greensand Formation or Kimmeridge Clay Formation (e.g. L15-FA-101); Wadden Volcaniclastic Member (e.g. Slenk-1); or unconformable contact with the Vlieland Sandstone Formation (e.g. Bolsward-1). The base of the upper member is the conformable contact with the Scruff Greensand Formation (e.g. in L15-FA-101, Vlieland Oost-1); the Wadden Volcaniclas-tic Member (e.g. Slenk-1, Zuidwal-2); or the lower member (e.g. Zurich Waddenzee-1, marked by a thin sand bed). The top of the upper member is the more or less conformable contact with the Vlieland Sandstone Formation of the Rijnland Group.
Lower Boundary The base of the lower member unconformably overlies the Lower Buntsandstein Formation or the Zechstein Gp.
Correlation In the Central Netherlands Basin a correlation with the Lower Saxony Basin (Niedersachsen Group) seems feasible. The (Portlandian) calcareous lower part (equivalent of the lower member of the Vlieland Basin (see pdf) ) could be roughly equivalent to the Weiteveen Formation, while the (Ryazanian) non-calcareous upper part (upper member) seems to reflect the Coevorden Formation
Distribution Restricted to the Vlieland Basin (see pdf) Herngreen, Smit and Wong (1991) and Central Netherlands Basin. The north-ernmost extension reaches offshore block L12. Some scattered, thin occurrences of similar deposits in the east of the province of Groningen could be assigned to this formation (RGD, in prep.).
Age In the Vlieland Basin (see pdf) : Late Kimmeridgian to most of the Ryazanian. Sporomorph zones Kräuselisporites sp. (Late Kimmeridgian, well Harlingen-1), Classopollis (Portlandian, several wells) and Cicatricosporites-Plicatella have been recognised Herngreen, Smit and Wong (1991) . The lower member of the Zurich Formation in well Harlingen-1 has yielded numerous ostracods: Cypridea binodosa, C. dunkeri carinata, C. granulosa granulosa, Eoparacypris weedonensis, Scabriculocypris trapezoides, Klieana alata, K. calyptroides, Bisulcocypris forbesi and others. The upper member in Vlieland-Oost-1 has yielded an association characterised by Klieana dictyota and Galliaecytheridea postsinuata. This association is characteristic for the Cinder Bed interval in Dorset (U.K., Portlandian/Ryazanian boundary) and Wealden 3 in the Lower Saxony Basin (late Early Ryazanian). The occurrence of this association in the upper member, which is considered as mid-/Late Ryazanian, points to the development of a similar facies at various moments in time. In the Central Netherlands Basin, Portlandian and Ryazanian ostracod and sporomorph associations have been found at various localities. Valanginian can be pres-ent in parts which are overlain by Vlieland Sandstone Formation of Hauterivian age.
Depositional Setting Deposited on a muddy coastal-plain, by settling from suspension during floodings. Thin sand sheets formed by crevasses, washovers, short transgressions and small-scale fluvial channels. The repeated intercalation of marine units reveals proximity of the sea. Coal beds indicate the existence of densely vegetated swamps, whereas carbonates point to lacustrine to restricted lagoonal deposition with periods of cessation of clastic sedimentation. Carbonates are predominantly bioclastic, lacustrine to lagoonal in origin.
Sequence Stratigraphy In the Vlieland Basin (see pdf) , the interval encompasses most of supersequence LZB 1. Maximum Flooding levels are reflected by concentrations of coal beds, calcareous soils, and marine incursions. Sequence boundaries generally are marked by thin, basal channel sands. The upper member reflects sequence LZB 1.6, while the lower member represents sequences LZB 1.1 to 1.5. In the Central Netherlands Basin the formation can represent sequences LZB 1.1 to LZB 2.5, depending on the time of the Rijnland Group transgression, which is mostly during the Hauterivian.
  In the Vlieland Basin (see pdf) , the formation can be subdivided into an informal ’upper member’ and ’lower member’, often separated by an incursion of either the Scruff Greensand Formation, Kimmeridge Clay Formation or the Wadden Volcaniclastic Member. The latter is a formal member of this formation. In the RGD, the informal names Harlingen mb. and Griend mb. have been applied for the upper, resp. lower member.
  SLD Delfland Subgroup
  SLDZ Zurich Formation
  SLDZV Wadden Volcaniclastic Member
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].