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De l’hypoxie saisonnière se produit actuellement sur la plateforme nord-ouest de la mer Noire. Cependant, à l’échelle de l’Holocène, peu d’études ont été réalisées sur les conditions d’oxygénation des zones côtières de la mer Noire. Deux carottes de sédiments, l’une provenant de l’embouchure du Danube (GC7, 215 cm) et l’autre de la baie d’Odessa (GC15, 297 cm), ont été prélevées dans le cadre du projet BenthOx visant à améliorer la compréhension de l’hypoxie en mer Noire. Les conditions d’oxygénation des eaux de fond ont été déterminées sur base des pyrites framboïdales. Aux profondeurs étudiées, le sédiment s’est déposé en environnement anoxique pour la carotte GC15 (diamètres moyens des pyrites framboïdales de 4 à 6 µm) et en environnement oxique pour la carotte GC7 (absence de pyrites framboïdales). Dans la carotte GC15, l’extraction séquentielle du fer réactif a montré une réduction du fer avec la profondeur avec une dominance de la pyrite dans le bas de la carotte. Ce comportement du fer semble lié à la dégradation de la matière organique. Suivant les analyses en composantes principales réalisées sur base des données XRF core scanner et de la teneur en matière organique estimée par les pertes au feu, le fer est corrélé avec les éléments détritiques dans la partie supérieure de la carotte GC15 et avec la matière organique et le soufre dans la partie inférieure. La carotte GC7 est plus homogène. Le fer y est corrélé avec la matière organique, le soufre et le brome. La fraction extractible à HCl (FeS, sidérite, ferrihydrite, akaganéite, lépidocrocite) est dominante dans toute la carotte GC7. Seasonal hypoxia currently occurs in the northwestern Black Sea shelf. However, little is known about oxygenation levels during the Holocene in coastal areas of the Black Sea. Two sediment cores, GC7 located in front of the Danube mouth (215 cm long) and GC15 in the Odessa Bay (297 cm long), were retrieved in the context of the BenthOx project. This project aims to improve the understanding of hypoxia in the Black Sea. Oxygenation levels of bottom water were determined by means of framboidal pyrites. At studied depths, sedimentation occurred in an anoxic environment for GC15 core (mean diameters of framboidal pyrites between 4 and 6 µm) and in an oxic environment for GC7 (no framboids). In the GC15 core, sequential extraction of reactive iron showed a reduction of iron with increasing depth. Indeed, pyrite is dominant in the core bottom. This iron behaviour is likely to be linked with organic matter degradation. Principal component analyses were calculated on XRF core scanner dataset, organic and carbonate contents estimated by loss on ignition. Iron is correlated with detrital elements in the top of GC15 core and with organic matter and sulphur in the bottom of this core. The GC7 core is more homogeneous. Iron is correlated with organic matter, sulphur and bromine. The HCl extractable fraction (FeS, siderite, ferrihydrite, akaganeite, lepidocrocite) is dominant in the entire GC7 core.

Mer Noire --- Danube --- baie d'Odessa --- sédiments de plateforme --- traceurs géochimiques --- hypoxie --- anoxie --- XRF core scanner --- fer réactif --- pyrites framboïdales --- Black Sea --- Danube --- Odessa Bay --- shelf sediments --- geochemical proxies --- hypoxia --- anoxia --- XRF core scanner --- reactive iron --- framboidal pyrite --- Physique, chimie, mathématiques & sciences de la terre > Sciences de la terre & géographie physique

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This Special Issue, focusing on the value of mineralogical monitoring for the mining and minerals industry, should include detailed investigations and characterizations of minerals and ores of the following fields for ore and process control: Lithium ores—determination of lithium contents by XRD methods; Copper ores and their different mineralogy; Nickel lateritic ores; Iron ores and sinter; Bauxite and bauxite overburden; Heavy mineral sands. The value of quantitative mineralogical analysis, mainly by XRD methods, combined with other techniques for the evaluation of typical metal ores and other important minerals, will be shown and demonstrated for different minerals. The different steps of mineral processing and metal contents bound to different minerals will be included. Additionally, some processing steps, mineral enrichments, and optimization of mineral determinations using XRD will be demonstrated. Statistical methods for the treatment of a large set of XRD patterns of ores and mineral concentrates, as well as their value for the characterization of mineral concentrates and ores, will be demonstrated. Determinations of metal concentrations in minerals by different methods will be included, as well as the direct prediction of process parameters from raw XRD data.

barite --- mineralogy --- industrial application --- beneficiation --- specific gravity --- bauxite overburden --- Belterra Clay --- mineralogical quantification --- Rietveld analysis --- machine learning --- artificial intelligence --- mining --- mineralogical analysis --- bauxite --- available alumina --- reactive silica --- XRD --- PLSR --- lithium --- quantification --- clustering --- Rietveld --- cluster analysis --- spodumene --- petalite --- lepidolite --- triphylite --- zinnwaldite --- amblygonite --- chalcopyrite --- ore blending --- copper flotation --- nickel laterite --- ore sorting --- framboidal pyrite --- sulfide minerals --- flotation --- process mineralogy --- heavy minerals --- ilmenite --- titania slag --- rietveld --- Magneli phases --- n/a