0000000000427265
AUTHOR
M. Yahaya
First carboniferous conulariids from Niger (west Africa)
Abstract Two new conulariid species, Paraconularia feldmanni sp. nov. and P. sahara sp. nov., are described from the Lower Carboniferous (Visean) Talak Formation of northern Niger. These are the first example of the genus Paraconularia to be reported from Africa and the first Carboniferous conulariids from that continent to be assigned to species level. Previously reported Carboniferous conulariids from Africa were collected from Morocco, assigned to other genera, and left in open nomenclature. Paraconularia is interpreted to have been cosmopolitan by the Early Carboniferous, and is the dominant genus in most assemblages of Carboniferous conulariids.
SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study
Abstract Background Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results NNVs were more favourable in su…
STRUCTURATION EXTENSIVE ET TRANSTENSIVE AU DEVONO-DINANTIEN DU BASSIN DE TIM MERSOÏ (BORDURE OCCIDENTALE DE L'AÏR, NORD NIGER).
International audience; L'étude tectono-sédimentaire préliminaire du bassin de Tim Mersoï confirme le contrôle exercé par les accidents majeurs N-S d'In Azaoua-Arlit, N30°E de Madaouéla et N70°E de Tin Adrar sur la géométrie du remplissage sédimentaire. Pour la période dévono-dinantienne, deux phases majeures de structuration ont été mises en évidence : une phase extensive, multi-épisode (du Dévonien au Viséen supérieur) et une phase transtensive débutant au Viséen terminal. Ces deux phases tectoniques majeures sont responsables de l'ouverture polyphasée du bassin. Pendant la phase extensive, la direction d'allongement qui était globalement N90°E au Dévonien, devient successivement N70°E pu…
Sedimentation in the Kandi extensional basin (Benin and Niger): fluvial and marine deposits related to the Late Ordovician deglaciation in West Africa
Abstract The Lower Paleozoic detrital succession of the half-graben Kandi Basin in West Africa (Niger-Benin) is about 600 m thick and rests unconformably on the Pan-African basement. Along the western edge of the basin, the base of the succession locally features large glacial fault-bounded paleovalleys. These valleys are filled by the lowermost continental deposits of the Were Formation characterized by massive diamictites with dropstones, and coarse to conglomeratic sandstones associated with large-scale channel structures and internal erosional truncations. The uppermost braided-river deposits of the Were Formation deposited across the entire basin are overlain by the Late Ordovician–Ear…
Évolution tectono-sédimentaire de l'unité d'Akokan au cours du Viséen dans le bassin de Tim Mersoï (région d'Arlit, Niger)
Resume Dans le bassin de Tim Mersoi, les facies greseux fins, argilo-silteux, de l'Unite d'Akokan, typiques de milieux tidaux, se substituent progressivement aux depots argileux sous-jacents a caracteres marins du Talak. Ils sont separes de la formation surincombante du Guezouman par une discontinuite erosive, largement representee dans la region, ce qui est un argument determinant pour leur rattachement au meme cycle sedimentaire que les Argilites du Talak sous-jacentes. Au cours du depot de cette Unite d'Akokan, des accidents cassants N60 °E a 80 °E apparaissent en bordure immediate de l'Air et engendrent des sous-bassins ou la serie devient de plus en plus epaisse. Le jeu continu de ces …