Considerations Paléogéographiques déduites de l’étude des Foraminifères des couches de passage du Viséen au Namurien (Bassins de Reggane et de Fort-Polignac, Sahara Central.)

The foraminiferal microfauna of the Visean Tethys is identical to that of the Gondwanian craton of North Africa, but differs from that of the Appalachian realm. This distribution contradicts the hypothesis of contiguity between Eurafrica and North America during the Carboniferous

Microfacies d’une lentille biohermale a la limite Eifelien/Givetien (Wellin, bord sud du synclinorium de Dinant)

A biohermal lens is described from the Eifelian-Givetian transition beds near Wellin (southern flank of the Dinant basin). The lens is about 200 m long and 45 m thick. It is composed of a central stromatopore-coral framestone (30 m) and of flanks of udoteacean packstone and stromatopore-brachiopod floatstone. The sedimentology based on two nearby sections indicate a regression. The log is based on the succession of 10 carbonate microfacies (MF1-10, standard sequence). The deepest microfacies (MF1) is open marine at the upper limit of the storm waves and the dysphotic-euphotic boundary. The shallower microfacies is partly emerged (lagoonal sediments, MF10). The framestone (MF7) is characterized by early isopachous cementation. Communities and fossil assemblages underline the important development of udoteacean meadows in the flanks while these algae play little or no role in the formation of the framestone. The bioherm covers a crinoidal sole (MF4), that is overlying the open marine facies (MF1-3). These show evidence of sulfate-reduction, with widespread bacterial (?) filamentous pyrite. Correlation between the two stratigraphic sections indicates that the architecture of the bioherm (central core and flanks) is planar (‘bank »). The total thickness of the studied succession is about 70 m. They grade from dysphotic-euphotic boundary estimated here around 20 m deep to emersion. Thus subsidence is here much more important than the eustatic regression. A new green udoteacean alga is described : Vignella nilsii n.gen., n. sp

Le Calcaire de Givetien à Givet

The authors recount the original definitions and the evolution of the conceptions of the Giuet Limestone and the Givetian at Givet. In order to end the existing confusion they define a Givet Group composed of three formations, which are, from base to top : Trois-Fontaines, Mont d'Haurs and Fromelennes Formations.Each of these formations corresponds to a third order positive-negative bisequence (marine facies - sabkha - marine facies), while second order sequences permit the recognition of thirty-two major phases which indicate the following environments : detrital and non-turbulent in the euphotic zone, reef, lagoon and of sabkha; minor first order sequences are recognized in those major phases.As for the Givetian, the authors make suggestions to be eventually examined by international bodie

Algues Viséennes du sondage de Turnhout (Campine, Belgique)

The article describes twenty-five algae, mostly green algae (dasycladaceans and codiaceans) observed in the Visean carbonates of the Turnhout borehole. Two species are new: Orthriosiphon turnhouti and Atractyliopsis weyanti</i

Carboniferous and Permian algal microflora, Tarim basin (China)

Thirty eight algal genera have been observed in Tournaisian to Kungurian carbonates of the Tarim Basin (China). Floral assemblages permit identification of ten stratigraphic levels. Most of the widespread and common forms have a "cosmopolitan" distribution, although Calcifolium is recognized for the first time in the eastern part of the Tethys

Biochemical and molecular diagnosis of erythropoietic protoporphyria in an Ashkenazi Jewish family

Summary: Erythropoietic protoporphyria (EPP) is a rare hereditary disorder due to a partial deficiency of ferrochelatase (FECH). The genotype of EPP patients features a mutation on one allele of the FECH gene and a common hypomorphic FECH IVS3-48c on the other allele (M/c). The resulting enzyme activity in patients is ∼35% of that in normal individuals. Ferrochelatase deficiency results in the accumulation of protoporphyrin in the skin, which is responsible for the clinical symptom of cutaneous photosensitivity in patients. In this study, we report the identification of a novel FECH mutation delT23 in an 11-member EPP family of Jewish origin. Two EPP siblings shared an identical genotype of delT23/IVS3-48c (M/c). They were both photosensitive and showed highly increased erythrocyte protoporphyrin. The genotype of the patients' mother, who did not present with any EPP clinical symptoms, was delT23/IVS3-48t (M/t). The patients' father, an offspring of consanguineous parents, was homozygous IVS3-48 c/c. He exhibited a mild photosensitivity, and an increase of 4-fold in erythrocyte protoporphyrin. His FECH mRNA amount was 71% of that of genotype t/t. It is the first reported case of an individual with c/c genotype who exhibits both biochemical and clinical indications of EPP. These results suggest that IVS3-48c is a functional variant of ferrochelatase. The clinical symptoms and biochemical abnormalities in the patients' father could be the result of an interaction between genetic and environmental factors. In addition, the frequency of IVS3-48c in the Ashkenazi Jewish population was estimated at 8%, which is similar to that in the European population

Sedimentologie paleoecologie et paleontologie des calcaires crinoidiques au voisinage de la limite couvinien-givetien a Wellin

The sedimentology of the Eifelian-Givetian boundary beds in the Wellin area indicates a transition from a siliciclastic-carbonate ramp to a gently sloping carbonate platform lacking a true reefal barrier. Prograding decametric sedimentary units form a littoral accretion megasequence. Corallian megafauna and algal microflora are highly diverse and abundant. Several communities are recognized in the ramp but they cannot be used for precise chronostratigraphic correlations.Comparison with other regions of the Dinant Synclinorium shows that the basin was already partitioned into blocks in Late Eifelian time. In Early Givetian several blocks of plurikilometric extension are identified. In this context, recognition of a new formation, provisionnally called "Formation X", between the Jemelle and Hanonet Formations, is significant.This local unit, some 120 meters thick, is composed of crinoidal and reefal limestones and indicates the existence of a sharply subsiding block in the Wellin area

Microfaciès d’une lentille biohermale a la limite Eifelien/Givetien (‘Fondry Des Chiens’, Nismes, bord sud du synclinorium de Dinant)

Microfacies of a biohermal lens at the Eifelian.Givetian transition (‘Fondry des Chiens’, Nismes, southern border of the Dinant Synclinorium). The biohermal lens of the ‘Fondry des Chiens’ belongs to the Eifelian-Givetian transition beds near Nismes (southern flank of the Dinant basin). The lens is 64 m thick and composed of a stromatopore-coral framestone. It is overlain by restricted lagoonal algal and cyanophycean facies near the emersion, and overlies Udoteacean and coral-bryozoan coverstones forming the flanks of two other unexposed lenses. Two crinoidal soles stabilized by syntaxial cementation constitute the substratum of these lenses. The reefal sedimentation is regressive. The log is based on the succession of 10 carbonate microfacies (MF1-10, standard sequence). The deepest microfacies (MF1) is open marine at the upper limit of the storm waves and the dysphotic-euphotic boundary. The shallowest sediments were partly emerged (lagoonal sediments, MF10). The exposed reefal lens (rudstones and framestones, MF6-7) and the flanks (grainstones, floatstones and coverstones, MF3-4-5) of the two other lenses are preserved due to early isopachous intergranular cement in the original cavities of the framestones or ‘intramicritic’ (replacement of the matrix) cementation in the floatstones and coverstones. The similarity of the facies and their algal content suggest that the sedimentary model proposed at Wellin is applicable at Nismes. Sequential analysis points to a three steps regressive evolution of the sedimentation probably related to a discontinuous subidence. The sequences have similar thicknesses (sixty or so meters) and grade from the dysphotic-euphotic boundary estimated here around twenty meters deep to emersion. As for Wellin, the subsidence is thus much more important than the eustatic regression

Oleanna (2012)

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