The Carboniferous period (about 359 Ma to 299 Ma) was divided between Dinantian (359 – 331 Ma) and Silesian. These two subsystems do not correspond to the two subsystems now defined in the Carboniferous system : Mississippian and Pennsylvanian, the base of the latter being situated in the lowermost part of the Silesian (about 323 Ma). However, the Belgian subdivisions remain in use because they correspond to two main paterns of deposition : carbonated for the Dinantian and siliciclastics with coal measures for the Silesian.
The Dinantian comprises the Tournaisian and Viséan stages, divided in five substages which are now largely used in Eurasia : Hastarian (Lower Tournaisian), Ivorian (Upper Tournaisian), Moliniacian (Lower Viséan), Livian (Middle Viséan) and Warnantian (Upper Viséan). The Dinantian succession was deposited along the southern edge of the Laurussia continent, in two major marine basins separated by the Anglo-Brabant Massif which corresponds to the Campine Basin in the north of Belgium and the Namur-Dinant Basin in the south of Belgium, northern France and Aachen area in Germany. The Dinantian of the Namur-Dinant Basin outcrops largely and was the type area for the historical subdivision of the lower Carboniferous, while the Dinantian of the Campine Basin outcrops only in the Visé area and is mainly known from boreholes.
The Dinantian deposits are almost exclusively limestones and diagenetic dolomites developed from limestones (mainly in the Tournaisian). They are the base for the recognition of 10 third-order eustatic stratigraphic sequences which can be traced everywhere.
The Namur-Dinant Basin is divided in 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 a incomplete stratigraphic succession with proximal carbonate facies ; the French Boulonnais is part of the NSA. The CSA has proximal facies with some gaps. The DSA has during the upper Tournaisian a relatively deep water sedimentation with the development of Waulsortian buildups ; it shows an evolution to shallow water facies during the Viséan. The VSA was part of the Namur-Dinant Basin during the Upper 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 were the classical stratotype for the Viséan. The ASA is in northern France and displays a very incomplete succession sometimes similar to those of the NSA. The VASA has the most incomplete succession with very proximal facies for the Tournaisian corresponding to periods of sea-level highstands, and no Viséan deposit.
In the Namur-Dinant Basin, small quarries extracts limestones for building stones (mainly in the Upper Tournaisian) and large quarries extract limestone for aggregates, cement and lime production.
The Campine Basin records mainly Viséan carbonates with numerous microbial/cryptalgal buildups, some of them being karstified and used for gas storage. The Viséan succession varies in thickness with respect to the general half-graben structure of the basin, the thickness of the deposits increasing southward to the Brabant Massif.
Recent papers
Denayer, J., Aretz, M., Poty, E. & Mottequin, B. 2016. Royseux : a palaeobiodiversity hotspot in the Late Viséan (Carboniferous) of Belgium. Geologica Belgica 19/1 : 7-20.
Mottequin, B., Poty, E. & Prestiani, C. 2015. Catalogue of the types and illustrated specimens recovered from the « black marble » of Denée, a marine conservation-lagerstätte from the Mississippian of southern Belgium. Geologica Belgica, 18 : 1-14.
Poty, E., Aretz, M. & Hance, L. 2014. Belgian substages as a basis for an international chronostratigraphic division of the Tournaisian and Viséan. Geological Magasin 151 (2) : 229-243.
