Carboniferous

 

On global and regional European time scales, the Carboniferous System is subdivided into a carbonate-dominated lower and a largely siliciclastic upper Carboniferous. The global time scale currently adopts the North-American division into Mississippian and Pennsylvanian Subperiods (see Enclosure A.1 of Section A;Harland (1989) , p. 42-43 for discussion). The equivalent European Subperiods (or Epochs) have been assigned the formal names Dinantian and Silesian.
The exact equivalent of the Mississippian-Pennsylvanian boundary in the Northwest European succession remains a point of debate. For the Netherlands a subdivision into Dinantian and Silesian is to be preferred. The name ‘Upper Carboniferous’ should be avoided, since it might create confusion as to whether the American (i.e. global) or European subdivision is intended.

Dinantian
Only a small number of wells has been drilled deep enough to reach the Lower Carboniferous in the Netherlands. These wells are located on the northern flank of the London-Brabant Massif and on the Mid North Sea High. Additional data on the Dinantien were gathered from released British offshore wells. Discussions with Mr. D. Cameron of the British Geological Survey and Mr. M. Dusar of the Belgian Geological Survey have proved very informative. Various lithostratigraphic units from the UK side have been adopted for the Netherlands. General information on the biozonation of the Dinantian can be found in Bless (1976) , Paproth et al (1983) , Streel (1992) and Riley (1993)
Geological history
The Dinantian heralded an epoch of high relative sea level. The sea transgressed the peneplained surface of the southern North Sea area and the London-Brabant Massif. On and around the massif a vast carbonate platform formed (Carboniferous Limestone Group; Zeeland Formation). Locally, under lagoonal conditions, dolomites and evaporites developed Bless (1976)
In the starved basinal areas south and east of the carbonate platform, a thin sequence of shales, bedded cherts and minor limestones accumulated. On the slope of the platform, carbonate deposits alternated with basinal shales (Goeree Member of Zeeland Formation). A thick sequence of clastic turbidites originating from the tectonically active Mid German High was deposited into the basin from the east, interdigitating with the basinal deposits (Kulm). Strong rift-related volcanic activity took place in this part of the basin Ziegler (1990) .
Further north, the Fenno-Scandinavian and the northern North Sea areas formed a large land mass. In the transition zone between land and sea, which was located approximately at the site of the Mid North Sea and Ringkøbing-Fyn Highs Ziegler (1990) , fluvial and deltaic sediments were deposited (Farne Group). Marine incursions into the deltas resulted in the deposition of carbonates in the overall sandy-clayey sediments (Yoredale facies of the Cementstone and Yoredale Formations). Fault-controlled differential subsidence considerably influenced the thickness distribution and facies patterns of the sediments Besly (1990) Grayson (1987) .
With the onset of the Silesian, a regressive trend commenced.

Silesian
The Silesian Series contains prolific and widespread coal resources. In the Netherlands, these were mined for centuries. Extensive coal exploration has been carried out in the provinces of Limburg and Gelderland (van Waterschoot van der Gracht (1918) ; Jongmans (1940) ; Peelcommissie (1963) ; Bachmann (1970) ; RGD (1986) ). Active coal mining in southern Limburg ceased late 1974. Coal exploration was focussed on Limburg and Gelderland (the Achterhoek). In the rest of the country, the interval is only known from hydrocarbon exploration wells. Most wells only penetrated the uppermost tens of metres of Silesian. Only a limited number of wells in settings where the Carboniferous itself formed an exploration target, have yielded data on deeper strata.
The historical European mining subdivision has traditionally served as a basis for the regional chronostratigraphic subdivision of the Silesian. It relies on marine bands (thin, widespread beds containing a marine fauna: goniatites, brachiopods, etc.), plant remains and ‘Tonsteine’ (weathered volcanic ash layers, which can be preserved in coal seams). Their use for hydrocarbon exploration purposes is restricted, since they are difficult to discern without cores or exposures. However, recognition of marine bands using spectral gamma ray wire-line logs has been demonstrated by Archard and Trice (1990) , Leeder et al (1990) and Hollywood and Whorlow (1993) .
The first lithological subdivision of the Dutch Silesian in ‘groups’, based on marine bands, was developed specifically for the South Limburg mining district (van Waterschoot van der Gracht (1918) ; Jongmans (1940) ; Jongmans (1940) ; see regional correlation (see pdf) ). van Wijhe (1974) Figure1) considered the old lithostratigraphic units of the Westphalian as formal formations.
The combination of a very uniform succession, without readily recognisable marker beds, and the small number of stratigraphic control wells, imposed restrictions on the first attempts to design a borehole-based lithostratigraphy. NAM and RGD (1980) placed the entire Silesian Series in the Netherlands in the Limburg Group. This group was tentatively subdivided into four units, of which the Tubbergen Sandstone Formation was the only one considered to merit a formal formation status. The bases of the Productive Measures and the Coal Measures were not defined, but these units were restricted to the coal-bearing interval of the group. The lowermost part of the group, roughly Namurian in age, was not attributed to any unit.
In the 1980’s the Geological Survey of the Netherlands (RGD) drilled a few wells that yielded long, completely cored sections of the Limburg Group in the southeastern and eastern Netherlands (van de Laar (1989) ; RGD (1986) ). This information and the data supplied by the continued hydrocarbon exploration have significantly improved stratigraphic control of the Silesian since 1980.
The Silesian history of the Netherlands presented here has evolved from key papers such as Pannekoek (1965) , Thiadens (1963) , van Wijhe (1974) , NAM (1980) , Ziegler (1990) , Besly in Glennie (1990) ), Cameron (1992) and Collinson (1993) .
Palynology (miospores), palaeobotany and macropalaeontology (goniatites, non-marine bivalves) are currently the main biostratigraphic tools. The palynological framework for the Silesian of Northwestern Europe developed from the work of Smith and Butterworth (1967) , van Wijhe (1974) , and Clayton (1977) . van Amerom (1975) , Kimpe (1978) and Paproth (1983) supplied bibliographies and syntheses of stratigraphic papers on the Silesian in the Netherlands and Belgium.
Figure C.1 (see pdf) presents the ranges of the main Silesian marker palynomorphs. The chart was compiled by three palynologists of the working group on Silesian lithostratigraphy (Mr. R.E. Dunay, Mobil; Mr. W.A. Boekelman, NAM and Mr. J.G.M. van de Laar, RGD). Figure C.2 (see pdf) shows the palaeobotanical biozonation of the Westphalian D, which was developed by the RGD during a comprehensive study of well De Lutte-6. The completely cored Silesian interval in this well has yielded important new information on the Westphalian D stratigraphy in the Netherlands (van der Zwan et al (1993) ; Pagnier and van Tongeren (1994) ).
Important contributions to the sedimentological understanding of the Silesian were published by Besly (1988) , Fielding (1986) , Guion (1988) , Cowan (1989) , Leeder (1990) , Diessel (1988) , Strehlau (1988) , Strehlau () , Strack (1989) , David (1989) ; David (1990) ; Selter (1990) , Pagnier (1987) , van de Laar (1989) van de Laar (1990) , van Amerom (1990) , Veld (1993) , Collinson (1993) , Bailey (1993) ,Besly (1993) , Jankowski (1993) , Chesnut (1993) , and Klauser (1993) . Sequence-stratigraphic concepts are frequently invoked to explain the depositional cyclicity observed in the Silesian deposits. The cycles are often attributed to climatic fluctuations that were associated with glaciations on the Southern Hemisphere Ramsbottom (1979) ; Ross (1988) ; Holdsworth (1988) ;Maynard (1991) Maynard (1992) ; Wagner (1993) ; Soreghan (1993) ; Chesnut (1993) ). The cycles show a non-periodic overprint from tectonics and ‘autocyclic’ depositional shifts, such as channel avulsion (Read (1973) ; Guion (1988) ;Klein (1992) ; Besly (1993) .
In some instances, the ‘Tonsteine’ have yielded radiometric datings and reliable correlations. Their characteristic mineral assemblages and widespread occurrence make them important correlation markers (Hedemann (1984) ; Lippolt (1984) ; Burger (1985) Burger (1990) Burger (1992) ; Lippolt (1984) ; Dusar (1989) ;Roberts (1993) ).
Structural setting
The end of the Dinantian coincided with the closure of the Rheno-Hercynian Zone, a back-arc basin to the north of the Variscan suture zone between Gondwanaland, Laurussia and various microplates (Franke and Engel (1988) ;Rajpoot (1991) ). This event was accompanied by extensive thrusting (‘Sudetic phase’). The thrust belt extends from southwestern Wales and England, through northern France, into central Germany. The resulting excess load induced the formation of a flexural foreland basin during the Silesian. This Northwest European Basin (‘Anglo-Dutch Basin’ of Cameron et al (1992) ) is bounded to the north by the Fennoscandian High and Grampian High. Its southern and eastern margins are formed by the North Amorican Block and the Rheno-Hercynian Zone Ziegler (1990) ). The latter are part of the actual Variscan orogen. The former are (pre-)Caledonian elements. The London-Brabant Massif played a subordinate role in palaeogeography till the Late Westphalian (C-D).
In Silesian times, several structural elements could be discerned in the Dutch part of the Northwest European Basin (see Section A, Figure A.2). The northern flank of the London-Brabant Massif was a block-faulted, WNW-ESE-trending plateau. Its southeastern part (in Belgium and the southern Netherlands) continued to subside throughout the Silesian. On its northwestern part (UK offshore), Silurian deposits are covered unconformably by Upper Westphalian C sediments. The Campine Basin is an elongate depocentre situated between the London-Brabant Massif and the Krefeld High - Maasbommel High complex. The area north of the Krefeld High appears to have been a more or less uniformly subsiding basin area during the Namurian and Westphalian A-B. The Cleaver Bank High (in the northwestern sector of the Netherlands offshore) shows a separate, coarser-grained development.
 
Uplift pulses occurred in the Westphalian C to D and Stephanian, related to the Asturian tectonic phase. The start of this phase is documented by incursions of sandstones, increasing differential subsidence and minor unconformities in the Westphalian C and D successions. Differential subsidence formed several north-south-trending depocentres such as the Ems Low (Selter, 1990; Tantow, 1993; van Tongeren, in prep.) and Proto-Central Graben. Their orientation is indicative of a northwest-southeast-oriented, transtensional regime, locally associated with igneous intrusives and even volcanism (both in Limburg Group and Lower Rotliegend Group: Eigenfeld (1986) ; Burger, Eckhart and Stadler (1962) ;Burger (1985) ; Burger (1992) ). Simultaneously, highs such as the Netherlands High, Achterhoek High and Groningen High (Westphalian A subcropping below Permian) formed in transpressional settings (Glennie (1981) ). In the transtensional areas (e.g. Ems Low and Lauwerszee Trough), Westphalian D(-Stephanian?) deposits are covered by Permian sediments. The effect of the Asturian phase cannot be discriminated reliably from that of the Early Permian Saalian uplift.
Depositional style
The Sudetic tectonic phase at the end of the Dinantian caused a rapid shift from carbonate to siliciclastic sedimentation near the London-Brabant Massif. In the vicinity of the Mid North Sea High this transition was more gradual. Combined carbonate and siliciclastic deposition continued here throughout the Dinantian (Farne Group, see Section B). This gradually changed into deposition of pure siliciclastic sediments during the Namurian A.
The Silesian sediments represent an orogenic foreland basin fill, showing an overall regressive megasequence. Provenance studies indicate that the Baltic Caledonides (north of the Mid North Sea High) and the Variscan orogen (to the south) acted as the main sources of Silesian sediment (Bless (1977) ;Frank (1992) ). Sediments filled the foreland basin simultaneously from the north and the south-southeast. In the Netherlands this resulted in the development of two depositional provinces. The northwestern province, comprising the Cleaver Bank area in the northwestern Netherlands offshore and adjoining UK offshore (quadrants 35 to 49), is characterised by sediments from a northern source. The combination of a large sediment input and a lower rate of subsidence gave rise to a relatively coarse-grained, proximal Silesian succession here.
In contrast, the southern province, which extended along the northern flanks of the London-Brabant Massif and the Rhenish Massif, was situated much closer to the tectonically active Rheno-Hercynian Zone. Due to thrust sheet loading, the area was subjected to extremely high rates of subsidence. The sediments, derived from the Variscan orogen to the south, were relatively fine-grained. Sediment infill and continued compression of the basin caused a gradual shift of the depocentre axis to the north (Drozdzewski (1992) ;Drozdzewski (1985) ).
The succession starts with marine to lacustrine basin and delta sediments, which grade upwards into coastal-plain deposits, the so-called ‘coal measures’. This facies is typical for the Pennsylvanian epoch across most of Europe, Asia and the Americas. It reflects cyclic sedimentation under humid tropical conditions, with periodic growth of extensive tropical forests, interacting with lakes, deltas, coastal and fluvial plains (van Wijhe (1974) ).
Deposition of the coal measures gradually ceased during the Late Westphalian C and Early Westphalian D, largely as a result of tectonic basin differentiation. A mid-Westphalian C influx of relatively coarse-grained, fluvial sandstones can be recognised practically throughout the Northwest European Basin. Fluvial deposition predominated during the Late Westphalian C and Early Westphalian D. The increasingly arid climate during this period caused a shift from grey, poorly-drained to well-drained red-bed facies. The first occurrence of red-bed facies has repeatedly been used as the base of a lithostratigraphic unit called ‘barren (red) measures’ (e.g. base Ketch Member of Cameron (1993) ; cf. Barren Measures of NAM (1980) ). However, sections that exhibit several consecutive red-grey transitions are quite common. This points to the non-unique, stepwise nature of this transition. Moreover, the transition occurred earlier along the basin’s margins than in its centre.
During the Westphalian D and Stephanian the fluvial systems gradually became more fine-grained in general, and sheet flood deposition predominated.

The new lithostratigraphy
To establish a new subdivision of the Silesian, the working group aimed for units that are based on lithological criteria. It should be possible to attribute any interval of the Limburg Group confidently to a formal lithostratigraphic unit without the need for extensive biostratigraphical studies or long cored intervals. Figure C.3 (see pdf) presents a schematic, north-south oriented litho-chronostratigraphic cross section across the Netherlands. It displays the positions of the new lithostratigraphic units in time and space. A comparison of the new stratigraphy with older subdivisions and the stratigraphic frame works of adjoining areas in the surrounding countries is presented in Figure B.2 (see pdf)
The Limburg Group is part of a huge depositional system. Along a single datum plane, facies may grade from proximal alluvial fan to euxinic deep marine. Conversely, similar facies can be encountered over a large stratigraphic range; this is mainly due to the pronounced depositional cyclicity. During each sedimentary cycle, the depositional facies belts shifted considerably. As a consequence, the boundaries of the various lithostratigraphic units may be quite diachronous.
It is possible to subdivide the Silesian regressive megasequence into four stages, which are reflected by four dominant lithofacies families (sensu Reijers (1993) ). In the new lithostratigraphic scheme, each lithofacies family has been placed in a separate subgroup.
 
The lowermost unit, the Geul Subgroup, displays a pattern of stacked, thick, coarsening-upward cycles without coal seams. It reflects the initial (marine to lacustrine) Silesian transgression. The depositional setting ranged from deep basin, via prodelta to delta front. The basal Epen Formation consists of basin-floor and prodelta fines with a few distal, turbiditic delta sandstone beds. The overlying Millstone Grit Formation comprises more proximal delta sandstones, alternating with basinal claystones. The unit consists of a large number of stacked depositional cycles, containing a thin transgressive interval (frequently with a basal marine band) followed by a thicker delta progradation phase. In the UK offshore, the Millstone Grit Formation progressively succeeds the Bowland Shale Formation (the local equivalent of the Dutch Epen Formation: Cameron (1993) ) from north to south. In the Netherlands a thin, distal equivalent of the Millstone Grit Formation, the Ubachsberg Member, occurs locally in the upper part of the Epen Formation.
The onset of peat (coal) deposition has been taken as the base of the Caumer Subgroup. The overall regressive trend reached a point at which the depositional cycles also included periods of delta-plain swamp deposition. This occurred first at the southeastern (Namurian A to B in the South Limburg-Aachen area: Steingrobe and Muller () ; RGD (1987) ) and northwestern (Namurian B to C in UK quadrant 41: Cameron (1992) ) margins of the Northwest European Basin. Peat deposition gradually expanded into the central basin zone, following the gradually regressing coast line. During the Early Westphalian A, peat deposition occurred throughout the Northwest European Basin.
In the northwestern province, the Caumer Subgroup is developed in a proximal, coarser-grained style. Fluvial and deltaic sandstones alternate with clay and coal deposits there. These deposits have been placed in the Klaverbank Formation (Namurian C/Early Westphalian A - Early Westphalian B). In the lower part of this formation the depositional cycles closely resemble those of the Millstone Grit Formation, but with intercalated coal seams. During the Late Westphalian A and Early Westphalian B, these deposits became richer in sandstone (Botney Member). The depositional cycles became more-or-less symmetrical trans- and regressive. In the rest of the Netherlands (southern province), age-equivalent deposits are developed in a finer-grained, distal style. The deposits have been attributed to the Baarlo Formation (Namurian B, C or Early Westphalian A to Late Westphalian A). Stacked regressive (coarsening-upward) cycles were formed, consisting of a thin, basal, basin claystone, gradually succeeded by prograding delta fines. This in turn was followed by more sandy delta deposits. Sandstones (mainly distributary channel fills and crevasses) and coal seams (interchannel swamps) are restricted to this latter stage.
In the southern province, a change in depositional style occurred in the Late Westphalian A. The depositional cycles became thinner and more symmetrically trans- and regressive. This change can be observed on wire-line logs, and has been taken as the base of the Ruurlo Formation (Late Westphalian A - Early Westphalian B). Through this unit the depositional cycles change upwards from regressive-dominated to transgressive-dominated. Additionally, the Ruurlo Formation displays an overall coarsening-upward trend, in which four consecutive regressive stages can be discerned. The oldest cycles show a succession of prodelta fines, covered by delta-plain fines with coal. In each subsequent stage, the interval of basinal fines deposition became less important, in favour of fluvial-plain deposits. The transitions between these four stages appear to be tectono-eustatically induced time lines. The transition of the first to the second regressive stage in the Ruurlo Formation has been correlated tentatively with the base of the Botney Member of the Klaverbank Formation in the northwestern offshore.
The transition from the Early- to the Late Westphalian B is marked by a lithostratigraphic boundary throughout the Netherlands. Both in the northwestern province (Klaverbank Formation) and the southern province (Ruurlo Formation) the overall coarsening-upward trend reached its maximum sandiness. This was succeeded by an abrupt change to the basin-wide deposition of lacustrine and flood-plain fines with prolific coal formation. These deposits have been placed in the Maurits Formation (Late Westphalian B - Early Westphalian C).
 
During the Early Westphalian C, swampy lake sedimentation started to give way to coarse-grained fluvial deposition in parts of the provinces of Gelderland, Utrecht, and northern Zuid-Holland. During the Late Westphalian C the same transition also occurred in the rest of the onshore. All sandstone-dominated Westphalian C/D-aged successions have been placed in the Dinkel Subgroup. The subgroup has been divided into several geographically confined formations: the Tubbergen Formation for the Ems Low area, the Hellevoetsluis Formation in the western-central Campine Basin, the Neeroeteren Formation in the eastern Campine Basin, and the Hospital Ground Formation of the northwestern province. In the Ems Low, massive, coarse-grained sandy to conglomeratic fluvial deposits formed closer to the sediment sources in Gelderland and central/eastern Twente. Towards central Drenthe, the youngest sandstone beds grade into mudstones. In the eastern offshore (e.g. well G18-01) the distal equivalent interval is developed as part of the fine-grained, coal-rich Maurits Formation. Therefore, a southern to eastern sediment source has been inferred (Rhenish Massif: Bless et al., 1977; F. David, 1990; Selter, 1990).
In the Campine Basin a proximal succession is found in the southeast of Zuid-Holland and Utrecht. Distal equivalents are found in western Zuid-Holland and in southern Limburg (lKemperkoul Member of the Maurits Formation). The Rhenish Massif and the Krefeld/Maasbommel Highs apparently acted as sediment source both for the Campine Basin and the Ems Low. The Netherlands High and the Achterhoek High probably acted as sediment sources as well. Arenaceous sediments derived from the southeastern hinterland first appeared in the Late Westphalian C, but increased significantly during the Westphalian D, with the deposition of the Neeroeteren Formation (Thorez (1977) ). A southeastern source is corroborated by van de Laar (1989) from palynological investigations which indicate that reworked palynomorphs occurring in the Westphalian C in the Limburg area (and presumably also in the Achterhoek area) are derived most likely from the Eifel and Rheinland/Sauerland regions in Germany.
Younger Westphalian deposits on the Cleaver Bank High, Groningen High, Achterhoek High, Netherlands High and Krefeld-Maasbommel High appear to have been reworked to some extent during the Westphalian C/D. However, deep truncation of the Netherlands High and London-Brabant Massif during that time is contradicted by maturation data. Burial history reconstructions from these highs suggest deep burial during the late Silesian (e.g. well Nagele-1: RGD, 1994). Some Westphalian C/D successions adjacent to highs or shoals (see Figure C.3 (see pdf) ) are developed in a distal facies (e.g. wells Kemperkoul-1 and Norg Zuid-1), indicating that these areas were not significant sediment sources.
Areas such as the western margin of the Ems Low, parts of the Cleaver Bank High and Central Netherlands Basin consisted of several terraces of tilted fault blocks. These acted as depositional terraces, accumulating condensed, relatively coarse-grained successions. These terraces could serve as intermittent local sediment sources.
During the latest Westphalian C - Westphalian D, the coarse-grained fluvial facies of the Dinkel Subgroup was gradually replaced by fine-grained flood-plain deposits. This occurred first in the basin centres. These finer-grained deposits have been placed in the Hunze Subgroup. Simultaneously, the predominant soil type gradually changed from poorly-drained hydromorphic, via ferruginous soils into well-drained caliches Besly (1988) ; van der Zwan (1993) ). This is accompanied by a gradual shift in colour of the flood-plain fines from grey to red-brown. These changes have been interpreted as reflecting an increasingly arid climate. Initially, semi-arid conditions occurred intermittently, but in the Late Westphalian D and Stephanian they became more permanent.
The Hunze Subgroup has been subdivided into three geographically restricted formations: the De Lutte Formation for the northeastern onshore, the Strijen Formation for the southwestern on- and adjacent offshore, and the Step Graben Formation for the northern offshore. Deposition of this subgroup may have continued into the Stephanian (van der Meer and Pagnier, in prep.), but deposits of this age have never been confirmed palaeontologically in the Netherlands.

The present-day top of the Limburg Group
Originally, the Silesian Series consisted of a sediment pile of more than 5000 m thick. Uplift and erosion during the latest Carboniferous and Permian resulted in locally deep truncation of the Limburg Group. Over most of the Netherlands, the Limburg Group subcrops beneath the Upper Rotliegend Group, in places exhibiting an angular unconformity. The Limburg Group is locally succeeded by the Lower Rotliegend Group (very locally, see Section D), Zechstein Group or younger deposits. Up to several tens of metres below the unconformity surface, secondary reddening can occur irrespective of the primary facies or colour. Discrimination between primary and secondary reddening is possible using palaeosol types (Besly (1988) ; van der Zwan (1993) ; Besly (1983) ). Calcic soil types are indicative for a primary reddening.
The complex erosion pattern of the top of the Limburg Group is illustrated by the Pre-Permian subcrop map in Figure C.4 (see pdf)

Seismic facies
The knowledge of the seismic appearance of the Limburg Group has increased significantly in recent years. The deep stratigraphic position of the unit, which is frequently overlain by a complex, locally halokinetically disturbed overburden, necessitates excellent-quality (3D) seismic data and advanced processing techniques.
On the other hand, in areas where little disturbance took place (Cleaver Bank High, Texel-IJsselmeer High (see pdf) , north flank of the London-Brabant Massif), fair results can even be achieved using 2D-seismics. Tantow (1993) studied the seismic appearance of the Silesian in the Ems Low area.Evans (1992) , Hollywood (1993) and Quirk (1993) described the Silesian seismic facies of the Cleaver Bank High area. The latter two have described three main seismic facies.
Figure C.5 (see pdf) displays the seismic appearance of the Silesian on the north flank of the London-Brabant massif and adjoining Campine Basin in the southwestern offshore (NOPEC regional seismic line SNST-83-1). Note the onlap pattern in the basal Limburg Group and the gradual shifting of depocentres.
seismic facies A:
basal unit, exhibiting moderate amplitude, low-frequency reflections of fair continuity. The reflections are mostly parallel, but in the Cleaver Bank and Campine Basin/London-Brabant Massif areas (Figure C.5 (see pdf) ) onlap patterns and thinning towards the crest of the highs can be observed. The unit corresponds to the Namurian and Westphalian A, which contains little or no coal, i.e. the Geul Subgroup and Baarlo Formation.
seismic facies B:
unit showing uniform thickness, consisting of very continuous, parallel reflections with high amplitudes and moderately high frequencies. Corresponds with the interval which shows maximum lithological variation, i.e. interbedded clays, sands and coals. Corresponds to the Ruurlo and Maurits Formation Fms. in the onshore and western offshore (Figure C.5 (see pdf) ) and the upper part of the Klaverbank Formation (Botney Member) and the Maurits Formation in the Cleaver Bank area.
seismic facies C:
more or less transparent interval containing a few, rather discontinuous, more or less parallel, low-amplitude, low-frequency reflections. It corresponds to the Dinkel and Hunze Subgroup.
DC Limburg Group
CF

Farne

Group
Regional correlation Regional lithostratigraphic correlation chart of the Devonian and Carboniferous for the Netherlands and neighbouring countries Regional lithostratigraphic correlation chart of the Devonian and Carboniferous for the Netherlands and neighbouring countries
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Structural element Silesian structural elements Silesian structural elements
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Chrono-stratigraphy Silesian litho-chronostratigraphic chart Silesian litho-chronostratigraphic chart
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  Dinantian litho-chronostratigraphic chart Dinantian litho-chronostratigraphic chart
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References See References Upper Carboniferous

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