Hastarian

The Hastarian Substage is the lower subdivision of the Tournaisian. Its base coincides with that of the Carboniferous as defined by the first appearance of the conodont Siphonodella sulcata. Unfortunately, the oldest siphonodellids are absent across the Devonian-Carboniferous boundary in the lower part of the Hastière Formation. The top of the Hastarian is defined by the base of the succeeding Ivorian substage (as emended by Hance et al., this volume) that is recognized by the first appearance of the conodont Polygnathus communis carina. The Hastarian correlates with foraminiferal Zones MFZ1 to MFZ4, rugose coral Zones RC1 and RC2 and the Siphonodella conodont Zone. Hastarian sedimentation occurred within a south-facing ramp setting. Thin-bedded crinoidal wacke- to packstones alternating with argillaceous limestones and thick-bedded crinoidal packtones form the dominant facies

Warnantian

The Warnantian Substage is about 8 to 12 Ma long and was defined as corresponding to the Cf6 Foraminifer Zone by Conil et al., 1977 (= MFZ13 to MFZ15 Zones of Devuyst & Hance (in Poty et al., in press). Its base is taken at the base of the Bonne River Formation (Fm); its top is defined by the base of the Namurian stage, but its upper part is almost completely missing in the Namur-Dinant Basin. The substage is covered by the RC7 and RC8 Coral Zones. It comprises the Bonne River and the Anhée Fms, which are mainly composed of shallowing-upward parasequences which were deposited by aggradation on the shelf, as suggested by their lateral regularity. It corresponds to the HST of the third-order sequence 8 (Thon-Samson Member of the Bonne River Fm) and to the third-order sequences 9 and 10 (Hance et al., 2001; Poty et al., 2002). The lower (MFZ13-MFZ14, RC7) and the upper Warnantian (MFZ15, RC8) can be correlated respectively with the British Asbian and Brigantian Substages

Livian

The Livian Substage is about 3-4 Ma long and was defined as corresponding to the Cf5 Foraminifer Zone by Conil et al., 1977 (= MFZ12 Zone of Devuyst & Hance, in Poty et al., in press). Its base is taken at the base of the "Banc d’or de Bachant"?, a bentonite capping the Moliniacian Neffe Formation (Fm). The top of the substage corresponds to the top of the Bay-Bonnet Member (Mbr) of the Grands-Malades Fm, below the appearance of the first foraminifers marking the base of the Warnantian Substage, at the base of the Thon-Samson Mbr (Bonne River Fm). The substage comprises the Lives Fm, including the Haut-le-Wastia, Corphalies and Awirs Mbrs, and the Grands-Malades Fm including the Seilles-Maizeret and Bay-Bonnet Mbrs. It is mainly composed of shallowing-upward parasequences which were deposited by aggradation on the shelf as suggested by their lateral regularity. The Livian Substage comprises the third-order sequence 7 (from the base of the Lives Fm to the top of the Seilles-Maizeret Mbrs) and the TST of the sequence 8 (Bay-Bonnet Mbr) of Hance et al. (2001). The Livian corresponds to the RC5g Coral Subzone and the RC6 Zone. The Livian can be correlated with the British Holkerian Substage

Moliniacian

The Moliniacian is the basal division of the Viséan in Belgium (regional Substage). Its base is identified by the entry of the foraminifer Eoparastaffella simplex in the Salet road section and correlates with the base of the Viséan Stage. Its top is defined by the base of the Livian Substage and coincides with a major bentonite, the ‘Banc d’or de Bachant’. It correlates with the late Chadian to Arundian of the British Isles and it provides a record of the final stage of the evolution of the Namur-Dinant Basin from a homoclinal ramp (in the Tournaisian) to a broad shelf of regional extend (end of the Moliniacian). It is characterized by varied facies reflecting different sedimentary environments across the basin and rich foraminifer and coral faunas that allow good biostratigraphic correlation. It is known from numerous sections in Belgium and Northern France

Viséan

The quality exposure of Viséan rocks in southern Belgium, the diversity of facies, the pioneer palaeontological works that started in the mid 19th century and the development of the foraminifer, conodont and rugose corals zonations in the last decades were the main elements for the promotion of the international use of the Viséan Stage. Southern Belgium is probably the best-documented area for the Viséan Stage in the world. In the Namur-Dinant Basin the submarine topographic irregularities inherited from the late Tournaisian and due to different sedimentation rates on the platform, in the basin and on the Waulsortian buildups were progressively smoothed out by the Viséan sedimentation. During the Tournaisian/Viséan transition, the central Dinant type area was in a peculiar, restricted environment and poorly fossiliferous, peri-Waulsortian facies developed. A new criterion for a better definition of the base of the stage was needed and has now been adopted. It is based on the evolutionary lineage of the foraminifer Eoparastaffella. A proposed new GSSP (Global Stratotype Section and Point) in Southern China (the Pengchong section) is still under discussion, but the term Viséan will remain as a stage corresponding to the Middle Series of the Mississippian Subsystem

Tournaisian

The main elements that prompted the international community to use the Tournaisian as a name for the oldest stage of the Mississippian Subsystem are the same as those for the Viséan, i. e., the quality of exposures in southern Belgium, the diversity of facies, the pioneering palaeontological work that started in the mid 19th century and development of foraminiferal, conodont and rugose corals zonations in the last decades. The numerous Tournaisian sections in southern Belgium document a progressive change in environmental setting, from a ramp during the early Tournaisian to a shelf during the late Tournaisian. The spectacular late Tournaisian Waulsortian buildups that occurred within 2 third-order sequences had a strong impact on subsequent Viséan sedimentation. Recent advances in understanding the sequence stratigraphy has led to new insights on correlation between the central Dinant Sedimentation Area and more proximal areas

Ivorian

The Ivorian Substage is the upper division of the Tournaisian. Its base, emended in this paper, corresponds to the first appearance of the conodont Polygnathus communis carina in the Yvoir railway station section. Its top is defined by the base of the Moliniacian Substage which corresponds now to the base of the Viséan. The Ivorian is characterized by a rich and diversified conodont fauna throughout and by a diversification of the foraminifers in its upper part. It is therefore very well zoned and precisely correlated across the Franco-Belgian Basin and beyond. Its upper boundary is marked by a drastic reduction of the conodont fauna and the disappearance of selected Tournaisian foraminiferal taxa. Ivorian sedimentation reflects the evolution of the Namur-Dinant Basin from a homoclinal ramp in the early Tournaisian to a broad shelf of regional extent in the late Tournaisian. Waulsortian buildups started growing in the distal part of the ramp during early Ivorian and formed a discontinuous barrier over the southwestern part of the Dinant Sedimentation Area. Distal peri-Waulsortian facies are dominated by cherty crinoidal wacke- to packstones, thick-bedded crinoidal packtsones, grainstones and dolostones. An oolitic grainstone, the Avins Mbr of the Longpré Fm, caps the Ivorian succession in the inner shelf. Proximal peri-Waulsortian facies are cherty crinoidal wacke- to packstones and purplish blue, poorly fossiliferous wacke- to packstones

Micropaleontologie du Moliniacien Belge. Trois nouveaux genres: <i>Halenopora (chlorophyceae), Aranea (Rodophyceae)</i> et <i>Globochernella</i> (foraminiferida, <i>tournayellidae</i>)

The description of three new genera, Halenopora (Chlorophyceae), Aranea (Rodophyceae) and Globochernella (Foraminifer, Tournayellidae), complete our knowledge on Belgian Dinantian micropalaeontology. Those fossils are almost abundant in Moliniacian

Edouard Poty: a bio- and bibliography

peer reviewe