Dinkel Subgroup DCD


Premise Unit, defined by Van Adrichem Boogaert and Kouwe (1995). The Dinkel Subgroup is the new equivalent of the Tubbergen Sandstone Formation of NAM (1980) . Prior to the definition of the Tubbergen Formation, the informal name ‘Twente Sandstone’ was also used repeatedly. The sandstone-dominated Upper Westphalian C sections in various parts of the Netherlands have been subdivided into four regionally confined formations. Palaeocurrent and provenance data suggests that these sediments were formed by separate, at least partly local, depositional systems.
Derivatio nominis Named after Dinkel river, which runs through the type area in the eastern part of the province of Overijssel, called Twente.
Type section Location map See figure (pdf)
  Well Tubbergen-8 (pdf)
  Location N 52°26’19.4
E 06°53’31.5
  Depth 2434 to 2930 m
  Length 496 m along hole
Definition Group of formations, comprising a thick succession of sandstone-dominated siliciclastic deposits with frequent interbedded mudstone intervals and occasional coal seams.
Correlation The Brig and Schooner Formations (lower Ketch Member) of Cameron (1993) are equivalent to the Dinkel Subgroup in the UK offshore.
Distribution The Tubbergen Formation is restricted to the Ems Low (pdf) and its western margin. The Hospital Ground Formation is found in the northwestern offshore. The Hellevoetsluis Formation is restricted to the western Campine Basin, whereas the Neeroeteren Formation is found in the southeastern sector of that basin.
Age Early/Late Westphalian C to Late Westphalian C/Early Westphalian D. Locally, sporomorph assemblages with a distinct ‘Stephanian/Autunian’ aspect can be found intercalated with typical Late Westphalian assemblages. Macrofloras indicate that the age of these intervals is Westphalian D. The seemingly younger palynomorph associations have been interpreted as having been imported from a more arid hinterland. In-situ palaeobotanical data tend to supply the most accurate datings. Palynological data appear to have a stronger palaeo-environmental overprint. The same effect has also been observed at the Westphalian C-D boundary. Especially in proximal developments along sub-basin margins typical ‘Westphalian D’ palyno-assemblages can occur throughout the Upper Westphalian C. Associated macrofloras reveal the actual Westphalian C age.
Depositional Setting The subgroup reflects interaction of fluvial-fan and flood-plain systems. All formations consist of an alternation of fluvial channel sandstones and flood-plain fines, with few coal seams. Marine influence is restricted to very scarce brackish-water fossiliferous bands (Bless (1977) ). The abrupt incursion of large amounts of coarser clastics in the Westphalian C points to tectonic uplift of the hinterland (Bless (1977) ; Leeder (1990) ; ‘Symon Unconformity’ of Cameron (1992) ). In the Upper Westphalian C and Lower Westphalian D the characteristic (reduced) grey colours of the older Limburg Group deposits gradually shift to (oxidised) primary red beds. This reflects better soil drainage (Besly (1983) ) and increasing climatic aridity Besly () Besly (1988) Besly (1990) ;Besly (1983) ; Besly (1993) ; van der Zwan (1993) . Red-bed deposition gradually spread out from the basin fringe.
Subdivision The Dinkel Subgroup comprises four formations, encompassing the sandstone-dominated upper part of the Westphalian in various areas in the Dutch part of the Northwest European Basin:
  DCDN Neeroeteren Formation
  DCDH Hellevoetsluis Formation
  DCDT Tubbergen Formation
  DCDG Hospital Ground 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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