The Carboniferous Period (c. 359-299 Ma) was formerly divided into the Dinantian (c. 359-330 Ma) and Silesian (c. 330-299 Ma) subperiods. Today, they do not correspond to the two subperiods recognised by the International Commission on Stratigraphy within the Carboniferous Period, i.e. the Mississippian and Pennsylvanian, the base of the latter being situated in the lowermost part of the Silesian (c. 323 Ma). However, the Belgian subdivisions remain in use because they correspond to two main patterns of deposition: carbonated for the Dinantian and siliciclastics with coal measures for the Silesian.
The regional Dinantian subsystem comprises the Tournaisian and Visean stages, divided into five substages that are now largely used in Eurasia: Hastarian (lower Tournaisian), Ivorian (upper Tournaisian), Moliniacian (lower Visean), Livian (middle Visean) and Warnantian (upper Visean). The Dinantian succession was deposited along the southern edge of the Laurussia continent, in two major marine basins separated by the Anglo-Brabant Massif. They correspond to the Campine Basin in northern Belgium and the Namur-Dinant Basin in southern Belgium. The Dinantian succession largely crops out in the Namur-Dinant Basin, which was the type area for the historical subdivision of the lower Carboniferous, while the Dinantian of the Campine Basin only crops out in the Visé area and is mainly known from boreholes ans seismic data.
In the Namur-Dinant Basin, the Dinantian deposits almost exclusively consist of limestones and diagenetic dolomites developed from limestones (mainly in the Tournaisian). These deposits form the basis for the recognition of 10 third-order orbitally-forced eustatic stratigraphic sequences that can be recognised worldwide. Two additional sequences cover the uppermost Visean but are lacking or very weakly developed in Belgium.
The Namur-Dinant Basin is divided into seven sub-basins having their own tectono-sedimentary evolution: the Hainaut (HSA), Namur (NSA), Condroz (CSA), Dinant (DSA), Visé-Maastricht (VSA), southern Avesnois (ASA), and Vesdre-Aachen sedimentation areas (VASA). The HSA is characterized by high subsidence rates, with the accumulation of up to 2500 m of limestones and dolomites including thick anhydrite units (up to 200 m thick). The classical Tournaisian type sections are located and still well exposed around the town of Tournai, in the HSA. The NSA displays an incomplete stratigraphic succession with proximal carbonate facies; the French Boulonnais is part of the NSA. The CSA displays proximal facies with some gaps. The DSA is characterized by a relatively deep-water sedimentation with the development of Waulsortian buildups during the late Tournaisian; it shows an evolution to shallow water facies during the Visean. The VSA was part of the Namur-Dinant Basin in the course of the Late Devonian and the Tournaisian, then evolved to a rapidly subsiding graben filled with deep marine limestone turbidites, separated from the Namur-Dinant Basin by the Booze-Le Val-Dieu ridge and connected to the Campine Basin; the disused quarries at Visé correspond to the historical stratotype of the Viséan. The ASA, situated in northern France, displays a very incomplete succession sometimes similar to that recognised in the NSA. The VASA has the most incomplete succession with very proximal facies corresponding to periods of sea-level highstands for the Tournaisian and the lower Visean. The boundary between the Dinantian and the Silesian is sharp, with a gap covering the uppermost Visean (upper Warnantian) in the DSA or the whole upper Visean in the NSA. The top of the Visean limestone can be locally strongly karstified.
In the Namur-Dinant Basin, numerous quarries extract limestones for building stones (mainly in the upper Tournaisian) and essentially to produce aggregates, cement and lime.
The Campine Basin records Tournaisian and Visean limestones with upper Visean microbial/cryptalgal buildups, some of them being karstified and used for gas storage (as in Loenhout). The Dinantian of the Campine Basin was recently revised (Laenen, 2003) and is the subject of seismic studies and drilling for the recognition of formations having good reservoir properties and that can be used for gas storage or having high geothermal potential (PanTerra, 2023). The Dinantian succession varies in thickness with respect to the general structure of the basin and not mainly by synsedimentary faults activity as previously stated.
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Denayer, J., Prestianni, C., Mottequin, B., Hance, L. & Poty, E., 2021. The Devonian–Carboniferous boundary in Belgium and surrounding areas. Palaeobiodiversity and Palaeoenvironments, 101, 313-356. https://doi.org/10.1007/s12549-020-00440-5
Hance, L., Poty, E. & Devuyst, F.-X., 2002. Sequence stratigraphy of the Belgian Lower Carboniferous – tentative correlation with the British Isles. In Hills, L.V., Henderson, C.M. & Bamber, E.W. (eds), Carboniferous and Permian of the World. Canadian Society of Petroleum Geologists, Memoirs, 19, 41-51.
Laenen, B., 2003. Lithostratigrafie van het pre-Tertiair in Vlaanderen, Deel II: Dinantiaan & Devoon. Studie uitgevoerd in opdracht van de Vlaamse overheid (ANRE). VITO-rapport 2003/ETE/R/095, 86 p.
PanTerra, 2023. Sedimentological reconstruction of the Campine Basin during the Dinantian. Vlaams Planbureau voor Omgeving, 123 p. https://archief.onderzoek.omgeving.vlaanderen.be/Onderzoek-6587723
Poty, E., 2016. The Dinantian (Mississippian) succession of southern Belgium and surrounding areas: stratigraphy improvement and inferred climate reconstruction. Geologica Belgica, 19/1-2, 177-200. https://doi.org/10.20341/gb.2016.014
Poty, E., Aretz, M. & Hance, L., 2014. Belgian substages as a basis for an international chronostratigraphic division of the Tournaisian and Viséan. Geological Magazine, 151/2, 229-243. https://doi.org/10.1017/s0016756813000587
