Tubbergen Formation DCDT


Premise Definition amended by Van Adrichem Boogaert and Kouwe (1995). The Tubbergen Sandstone Formation was the single unit in NAM (1980) Limburg Group that was allocated a formal formation status. The type section has been amended here: the argillaceous sandstones found in the Upper Westphalian B are now excluded. The lithological suffix has been omitted.
Derivatio nominis Named after the Dutch province of Limburg.
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
Additional section Location map See figure (pdf)
  Well Dalen-7 (pdf)
  Location N 50°59’36.9
E 06°47’36.8
  Depth 3507 to 3868 m
  Length 361 m along hole
  Well Norg-Zuid-1 (pdf)
  Location N 53°01’27.5
E 06°27’09.8
  Depth 3456 to 3678 m
  Length 222 m along hole
Definition (modified after NAM (1980) ) Succession of grey to white or pink to red sandstone beds of variable thicknesses, alternating with mudstones and rare coal seams. Sandstone intervals make up between 30 and 70% of the succession. The sands are fine- to very coarse-grained, occasionally grading up to pebble size, moderately-sorted and subangular. The sandstones occur in channel fills of 5 to 20 m thick, yielding blocky log patterns, but these can occur stacked into massive intervals of up to 100 m thick. Intercalated mudstone sections are predominantly light-grey or greenish grey. Coal seams are associated with grey intercalations of 5 to 50 m thick. Purple or red-brown intervals become dominant in the youngest parts.
Upper Boundary The upper transition into the De Lutte Formation is marked by an abrupt upward increase in the thickness of the mudstone intercalations. The boundary has been placed at the top of a major sandstone bed, which is overlain by an interval of at least 40 m thick which consists predominantly of mudstones. The upper Maurits Formation and the basal De Lutte Formation are partial fine-grained lateral equivalents of the oldest, resp. youngest part of the Tubbergen Formation. The Tubbergen Formation grades into the Hellevoetsluis Formation in the province of Utrecht.
Lower Boundary The base is marked by the first appearance of thick-bedded sandstones. This is generally accompanied by a marked decrease in the frequency of coal seams, compared with the underlying Maurits Formation.
Distribution Northeastern part of the Netherlands, in the Ems Low and on its western flank, passing over into the Lauwerszee Trough. For the distribution of equivalent counterpart in Germany, see Hedemann (1984) ; Selter (1990) ; Tantow (1993) ).
Age In NAM and RGD (1980) the formation was defined as Late Westphalian B to Early Westphalian D. After its redefinition, the age ranges from Early Westphalian C to Late Westphalian D. The sandstone beds have a variable extent into the basin. Beds from the top and the base of the formation can grade into fines to the north (compare Tubbergen-8 with Norg Zuid-1). Hence both top and base of the formation are diachronous. The transition from the Maurits Formation to the Tubbergen Formation occurred first on the basin fringe, and gradually shifted into the basin. It occurred consecutively in central Gelderland (Early Westphalian C), eastern Overijssel - southern Drenthe (mid-Westphalian C), and northern Drenthe - Groningen (Late Westphalian C). The transition of the Tubbergen Formation to the De Lutte Formation occurred first in the centre of the basin, and moved towards the margin. In the north of Drenthe it occurred during the latest Westphalian C. In western Twente, deposition of the Tubbergen Formation persisted into the Late Westphalian D.
Depositional Setting The massive, thick sandstone intervals of the formation are sheets of amalgamated braided fluvial channel fills. Thinner sand-/siltstone beds and fines were deposited as overbank deposits. The grey colours in the fines and the associated coal seams indicate predominant poorly-drained overbank soil conditions. The upward shift to variegated and red colours reflects an increase in aridity and improving soil drainage. The formation shows interbedding of sandstone-dominated and mudstone-dominated sections. These can be correlated on a local and regional scale. The depositional cyclicity is reflected here by alternating periods of fluvial channel and flood-plain deposition. The massive sheet sandstones demonstrate fair lateral continuity, but individual sand bodies can show considerable variations in character. Isolated, thin, flood-plain-associated channel sandstones have been interpreted as transitional to high-sinuosity channel fills (shoestring sands).
Subdivision In the south-east of the province of Drenthe, NAM has subdivided the formation into several reservoir units (Krim, Hardenberg, Gramsbergen and Dalen members). In Twente and adjoining Germany a comparable subdivision into a ‘K’- and an ‘L’-sandstone unit is used.
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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