Limburg Group DC


Premise Definition amended by Van Adrichem Boogaert and Kouwe (1995).
Premise The original definition of NAM and RGD (1980) has been modified considerably. Type well Rijsbergen-1 (see pdf) (see pdf) is located in a complex structural setting, where a significant fault zone crosses the Limburg Group interval. As a consequence of the poor quality of the available seismic data, the impact of this fault cannot be determined completely. In addition, the interval 1353-1434 m is currently interpreted as a condensed succession of the Upper Rotliegend, Zechstein and Lower Buntsandstein Groups.
  Various types of intrusive rocks have been encountered in this interval Eigenfeld (1986) , mostly much younger than the surrounding Silesian sediments. Such intervals have been referred to the Igneous Rocks Group (XX in Section G of this publication) without a formation connotation. Volcanic rocks that are intercalated in a stratigraphic sense, are rare and thin. These (a.o. ‘Tonstein’ bands) are obviously a part of the Limburg Group.
Derivatio nominis Named after the Dutch province of Limburg.
Type section Location map See figure (pdf)
  Well Rijsbergen-1 (pdf) (pdf)
  Location N 51°31’44.3
E 04°41’21.6
  Depth 1434 to 4644.5 m
  Length 3210.5 m along hole
Additional section Location map See figure (pdf)
  Well Kemperkoul-1 (pdf)
  Location N 50°59’36.9
E 05°53’07.0
  Depth 489 to 1665 m
  Length 1176 m along hole
Definition A group of clastic formations, forming a thick, monotonous succession of mostly grey to black, fine-grained siliciclastic sediments commonly containing intercalated coal seams in the middle and upper parts. Fossiliferous marine beds are frequently intercalated in the oldest parts, but these become scarce in the middle parts, and are absent from the youngest interval. The group also comprises light-coloured, massive sandstones, and primary red-bed intervals without coal seams. Volcanic beds (mostly mm-thin tuff layers) can be intercalated locally. The basal interval commonly consists of a black, bituminous shale, locally containing silicified limestone laminae. Secondary reddening is frequently observed beneath the top unconformity.
Upper Boundary Practically all formations of the Limburg Group can be overlain unconformably by the Lower Rotliegend Group (volcanics, volcaniclastics, red beds), Upper Rotliegend Group (red-bed clastics, evaporites), Zechstein Group (claystones, carbonates, evaporites), Rijnland Group (glauconitic sands, clays, marls), or Chalk Group (glauconitic sands, marl and chalk). In the specific unit definitions these truncated situations will not be mentioned separately. Over large areas, late-diagenetic reddening has penetrated several tens of metres into the top of the Limburg Group. If a reddened interval of the Limburg Group is covered unconformably by a younger red-bed unit, the exact boundary can be difficult to pick.
Lower Boundary The base is poorly known because only a few wells in widely separated areas reached it. Towards the London-Brabant Massif, the group rests on the carbonates (frequently silicified) of the Lower Carboniferous Limestone Group (Dinantian). Around the Mid North Sea High, the group grades into an alternation of carbonates and clastics of the Yoredale Formation (Farne Group).
Correlation In the UK offshore adjoining the Dutch quadrants P and K, the Westoe Coal Formation is the equivalent of the Baarlo, Ruurlo and Maurits Fms. Adjoining Quadrants J and D the Caister Coal Formation corresponds with the Klaverbank Formation. The Westoe Coal Formation is equivalent to the Maurits Formation there Cameron (1993) . The basal interval of the Schooner Formation can be correlated with the youngest interval of the Maurits Formation.
Distribution The group is found over practically the entire on- and offshore of the Netherlands. As a result of erosion, it is missing on the London-Brabant Massif and the crest of the Elbow Spit High - Mid North Sea High (see Figure C.4). Some outcrops can be found in the valley of the river Geul in the south of the province of Limburg (e.g. Heimans Quarry).
Age Namurian and Westphalian. The existence of Stephanian deposits in the Netherlands has not yet been confirmed. Stephanian deposits have frequently been reported from neighbouring parts of Germany (a.o. Hedemann et al (1984) . Selter (1990) ), but these occurrences are currently being re-evaluated (e.g. Tantow (1993) ). For an overview of palynological markers found in the Limburg Group, see van Wijhe (1974) , Clayton (1977) and van de Laar (1990) , and Figure C.1.
Depositional Setting The deposits reflect an overall regressive deltaic foreland-basin fill ( van Wijhe (1974) ,;Ramsbottom (1979) ; Ramsbottom (1987) ; Guion (1988) ). The oldest interval consists of marine and lacustrine basin-floor fines and turbiditic distal deltaic deposits. The middle part is dominated by an intercalation of deltaic and fluvial-plain deposits. The youngest interval is characterised by (locally coarse-grained) fluvial-plain deposits, some of which exhibit a primary red-bed facies. Marine influence gradually decreased in time. Sediments, flora and fauna indicate a practically non-seasonal, tropical, humid climate during the Namurian and Westphalian A to C. The widespread occurrence of primary red beds, calcic soils and the rare occurrence of coal seams in the Upper Westphalian C and D (Hedemann (1984) van der Zwan (1993) ) indicate a more seasonal, tropical semi-arid climate during the late Westphalian.
Subdivision The Limburg Group has been divided into four subgroups. Each subgroup reflects a certain phase of the Silesian regressive megasequence. Most formations are restricted to distinct depositional provinces or basins. In this subdivision the Caumer Subgroup corresponds roughly with the Productive Measures of NAM and RGD (1980) . The Dinkel Subgroup replaces the former Tubbergen Sandstone Formation. The redefined Tubbergen Sandstone Formation is restricted to the type area in eastern Overijssel and Drenthe. The Hunze Subgroup largely replaces the Barren Measures.
  DCG Geul Subgroup
  DCGE Epen Formation
  DGCM Millstone Grit Formation
  DCC Caumer Subgroup
  DCCU* Maurits Formation
  DCCR Ruurlo Formation
  DCCB Baarlo Formation
  DCCK Klaverbank Formation
  DCD Dinkel Subgroup
  DCDN Neeroeteren Formation
  DCDH Hellevoetsluis Formation
  DCDT Tubbergen Formation
  DCDG Hospital Ground Formation
  DCH Hunze Subgroup
  DCHS Strijen Formation
  DCHL De Lutte Formation
  DCHP Step Graben 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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