Farne Group CF

 

Derivatio nominis Named after the Farne Islands off the north-east coast of England. The group has been defined in the United Kingdom by Cameron (1993) .
Type section Location map See figure (pdf)
  Well E06-01 (pdf)
  Location N 54°46’09.6
E 03°42’09.9
  Depth 2213 to 2755 m
  Length 542 m along hole
Definition A group of claystones and sandstones with minor coal seams, and a variable amount of intercalated limestone and dolomite beds.
Upper Boundary The top of the group has been placed at the top of the highest limestone. Here the typical coarsening upward claystone/sandstone sequences of the conformably overlying Epen Formation (Limburg Group) begin. In areas which were subjected to later erosion, the group is overlain unconformably by younger formations (Rotliegend to Chalk).
Lower Boundary The group overlies the Old Red Group conformably. Its base is marked by the lowermost carbonate bed.
Correlation The relationship with the Condroz Sandstone, which occurs in the Namen Basin in Belgium and the adjoining area in Germany (see Fig. B.2), is not very clear. This sandstone appears to thin rapidly from the south and the east towards the London-Brabant Massif (Bless (1977) ) and grade laterally into the Bosscheveld formation.
Distribution The limited amount of data available indicates the presence of the formation in the Dutch offshore in the Elbow Spit High area and on part of the Mid North Sea High. In the United Kingdom it supposedly occurs in an extensive area along the southern flank of the Mid North Sea High. The development further to the south and the possible transition into the Carboniferous Limestone Group are unknown because of a lack of well data.
Age The age of the group ranges from Tournaisian (Courceyan) to late Visean/early Namurian, as defined on the basis of palynomorphs. Palynomorph biomarkers including Perotrilites tesselatus, Rotaspora knoxi, Tripartites trilinguis, Raistrickia nigra, Tripartites distinctus, Vallatisporites vallatus, Vallatisporites ciliaris, Murospora margodentata, Murospora parthenopia, Auraspora macra, and Schopfites claviger yield ages from Courceyan to Arnsbergian.
Depositional Setting The group was deposited under paralic conditions. Periods of active delta-front deposition alternated with repeated marine incursions, during which marine limestones and claystones were formed. In places a fluvial regime prevailed, resulting in a thick succession of stacked channel fills.
Subdivision The group has been subdivided into formations on the basis of the distribution of carbonate beds. From top to bottom these are:
  CFYD Yoredale Formation
  CFEB Elleboog Formation
  CFC Cementstone Formation
References See References Upper Carboniferous

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