23 research outputs found

    Paleoecologie et interpretation sedimentologique du "marbre noir" de Denée (Viseen inferieur, Belgique)

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    Paleoecology and sedimentological interpretation of the "black marble" of Denée (Lower Visean; Belgium). The paleoecology of the "black marble" of Denée (Dinant sedimentation area (DSA), Belgium) is reviewed in light of recent paleoecological, taphonomic and sedimentological investigations. This "conservation-Lagerstätte" is famous for its very well preserved fossils (echinoderms, fish, graptolites, etc.). During the Lower Visean, the "black marble" deposited in a confined basin bordered to the south by the Waulsortian mud mounds, and progressively filled by calcareous sediments, probably turbiditic, coming from the transition area between the DSA to the south and the Condroz sedimentation area to the north. During lowstand periods, the paleoenvironment was submitted to anoxic/dysoxic conditions which developed due to confinement by the Waulsortian buildups. The poor oxygenation of deep waters permitted the installation of a particular benthic fauna (graptolites, bivalves ("paper pectens"), echinoderms,…) and, combined with rapid sedimentation, favoured excellent preservation conditions by excluding the development of necrophagous and saprophagous organisms

    Revision of the brachiopod <i>Cyrtina rigauxi</i> MAILLIEUX, 1909 and description of a new ambocoeliid genus (<i>Dionacoelia</i> n. gen.) from the Frasnian of southern Belgium

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    Cyrtina rigauxi MAILLIEUX, 1909 is transferred to the genus Acutatheca STAINBROOK, 1945 thus mentioned for the first time in the Frasnian of the Dinant Synclinorium and Roly "Massif (Neuville Formation, Lower Palmatolepis rhenana Zone). MAILLIEUX (1940, 1941) included Acutatheca rigauxi in Cyrtina demarlei BOUCHARD (nomen nudum) and C. heteroclita (DEFRANCE, 1824). The specimens identified as Martiniopsis (Elivella) rigauxi by MAILLIEUX (1940, 1941) [= Echinocoelia rigauxi sensu VANDERCAMMEN (1956)] do not belong to C. rigauxi MAILLIEUX, 1909. They are redescribed as Dionacoelia secessus n. gen., n. sp., a species occurring with certainty in the Ermitage Member of the Moulin Liénaux Formation (Palmatolepis punctata Zone)

    A new representative of the lichid genus Ohleum (Trilobita) from the Eifelian (Middle Devonian) of southern Belgium

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    Trilobites of the family Lichidae are relatively poorly diversified within the Eifelian mixed siliciclastic-carbonate succession of the southern margin of the Dinant Synclinorium (Belgium). Until now, they were only represented by species belonging to the genera Ceratarges and Eifliarges. The recent discovery of a well-preserved specimen within the Eifelian-aged Jemelle Formation in the Couvin area led us to propose the first detailed description of a representative of the genus Ohleum (O. magreani sp. nov.) in the Ardenne

    Lower and Middle Famennian (Upper Devonian) rugose corals from southern Belgium and northern France

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    After the late Frasnian extinctions, the rugose corals slowly recovered during the Lower and Middle Famennian (crepida to marginifera conodont zones) in southern Belgium and northern France (Avesnois) (Namur–Dinant Basin). Six genera represented by seven species are recognized and described here; one species (Breviphrentis superstes) is new. The rugose coral fauna described herein includes small solitary forms belonging to the so-called Cyathaxonia fauna and is similar or very close to those previously described within the same stratigraphic interval in Australia, China and Germany. It also contains a large species belonging to the genus Breviphrentis which was considered as extinct since the end of the Givetian (Middle Devonian) (“Lazarus taxon”). The tabulate corals from the Lower and Middle Famennian of this area, mainly represented by auloporids, are also briefly discussed. Rugosa only constituted a minor part of the fauna after the end-Frasnian crisis in the Namur–Dinant Basin contrary to the brachiopods, which were abundant and relatively diversified, and no rugose corals have been recovered from the early Lower Famennian (triangularis Zone). The first important Famennian coral radiation only took place during the Latest Famennian (Strunian)

    A bryozoan fauna from the Mississippian (Tournaisian and Viséan) of Belgium

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    © 2017 Elsevier Masson SASEleven bryozoan species are described from the Mississippian of southern Belgium, including one new species, Atactotoechus vaulxensis, and one species left in open nomenclature (Stenophragmidium sp.). From this fauna, four species are restricted to the Tournaisian stage, and seven occur in the Viséan. The fauna is mainly small-sized, represented by branched ramose, encrusting and reticulate growth forms. Bryozoans in the Mississippian of southern Belgium preferred deeper, clay-rich environments. The identified bryozoan species are mainly distributed within the European basin, with some similarities with the Mississippian faunas of Siberia and Kazakhstan

    New observations on some Upper Devonian brachiopods from the Namur-Dinant Basin (Belgium)

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    Brachiopods (Productida [except Chonetidina], Orthida, Athyridida, Spiriferida [Adolfiidae, Reticulariidae, Ambocoeliidae, Thomasariidae], and Spiriferinida) recovered in the interval, in terms of the standard conodont zonation, between the Palmatolepis hassi and P. triangularis zones (Late Middle Frasnian to Early Famennian) in the Namur-Dinant Basin (Belgium) are described. The orders and suborders investigated include 32 species: 21 are described in open nomenclature, seven are previously known, four are new of which three are assigned to previously known genera: Aulacella aggeris n. sp., Dicamara plutonis n. sp., and Warrenella (Warrenella) aquaealbae n. sp. The fourth species belonging to a newly defined genus: Neptunathyris buxi n. gen., n. sp. A major brachiopod faunal change occurs at the top of the P. rhenana Zone in southern Belgium, with the disappearance of most existing species in parallel with the deterioration of the oxygenation conditions preceding the Upper Kelwasser Event. Only an impoverished fauna (Lingulida, Chonetidina, Rhynchonellida) has been collected in the P. linguiformis Zone. The recovery of the Famennian brachiopods after the end-Frasnian biotic crisis was rapid in the basal Famennian but, despite their great abundance, their diversity was relatively low. New cosmopolitan genera appeared at this time especially among the rhynchonellids, athyridids and spiriferids with new species of pre-existing orthid and orthotetid genera
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