Uranium mineralization associated with late magmatic ductile to brittle deformation and Na–Ca metasomatism of the Pan-African A-type Zabili syntectonic pluton (Mayo-Kebbi massif, SW Chad)

Vanderhaeghe, Olivier; André-Mayer, Anne-Sylvie; Diondoh, Mbaguedjé; Eglinger, Aurélien; Ohnenstetter, M.; Isseini, Moussa; Cuney, Michel; Poujol, Marc; Marieke, Van Lichtervelde

doi:10.1007/s00126-020-00999-1

Cited by 8 publications

(4 citation statements)

References 99 publications

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“…Several previous investigations have revealed the existence of radioactive elements and toxic heavy metals in this region (Oyamta, 2013;Penabei et al, 2018;Ajani et al, 2020;Ajani et al, 2022, Olivier et al, 2021. A prior work of ours (Penabei et al, 2018) reported on the assessment of natural radioactivity levels and associated radiological risks in building materials in the vicinity of mining and exploration sites in the Mayo-Kebbi region.…”

Section: Introductionmentioning

confidence: 81%

Health risk assessment and statistical analysis of natural radioactivity in the uranium exploration area of Zabili, Chad

Penabeï

Bongue

Hazou

et al. 2022

International Journal of Environmental Analytical Chemistry

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Section: Introductionmentioning

confidence: 81%

Health risk assessment and statistical analysis of natural radioactivity in the uranium exploration area of Zabili, Chad

Penabeï

Bongue

Hazou

et al. 2022

International Journal of Environmental Analytical Chemistry

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“…The plot indicates the association of mineralisation with low Mg chlorites (Figure 12i). The Q and P parameters in the classification scheme [53,54] are defined as: P = K − (Na + Ca) and Q = Si/3− (K + Na + 2Ca/3) where P discriminates between K-feldspar and/or biotite (high P-values) and albite (low Pvalues). The Q parameter estimates the quartz content of a rock [54].…”

Section: Discussion and Summarymentioning

confidence: 99%

“…The Q and P parameters in the classification scheme [53,54] are defined as: P = K − (Na + Ca) and Q = Si/3− (K + Na + 2Ca/3) where P discriminates between K-feldspar and/or biotite (high P-values) and albite (low Pvalues). The Q parameter estimates the quartz content of a rock [54]. Albitisation is evident from the Q-P diagram (Figure 12j).…”

Section: Discussion and Summarymentioning

confidence: 99%

Polymetallic Uranium Mineralisation in Rohil, Rajasthan, Western India: Insights from Mode of Occurrences, Structural Controls, Alteration Geochemistry and Exploration

et al. 2023

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Geological and radiometric studies of outcrops aided by extensive subsurface exploration through drill holes in an otherwise soil-covered terrain revealed the existence of low grades, medium tonnage, and metasomatite types of polymetallic uranium deposits at Rohil in India. Microscopic studies, electronprobe micro analyses, and geochemical analyses of samples from lodes indicate the polymetallic nature of mineralisation involving copper and molybdenum, in addition to uranium. Wide variations in the composition of fluid (S-, F-, P-, and O-rich) led to the formation of sulphides, fluorite, U-phosphosilicate, quartz, and magnetite, respectively, and are associated with uraninite. Litho-geochemical analyses from the Rohil deposit indicate multifarious metasomatic alterations associated with polymetallic mineralisation occurring in veins. The major mineralogical and metasomatic controls on rock compositions and the extent of material transfer processes that influenced the host rocks and mineralisati on are quantified by molar element ratio studies and alteration plots. General element ratio (GER) diagrams on chemical analyses of rock samples reveal albitisation and chloritisation as major and microclinisation, sericitisation, carbonatisation, and silicification as minor wall rock alterations associated with ore mineralisation. The alteration box plot between the chlorite–carbonate–pyrite index (CCPI) and the Ishikawa alteration index (AI) indicates the influence of hydrothermal activity and dominance of both albitisation and chloritisation. The ore zone is controlled by meso- and microstructures and the geometry of the soda- and potash-metasomatised zone around hydrothermal veins. This zone contains several anastomosing mineralised veins defined by a prominent joint that is set in quartzite that strikes subparallel to the axial surface of the F2 isoclinal folds and the pervasive schistosity S1 in the quartz–feldspar–biotite schist. Aventurisation of albite and microcline, established through electron probe micro analyses, can be considered as a pathfinder for uranium mineralisation. The close association of uranium and metallic sulphide mineralisation with microstructural, mineralogical (albitisation, chloritisation, and microclinisation), and geochemical variations can be applied as suitable exploration guides in a similar geological set-up worldwide.

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“…Low-temperature Au deposits at Witwatersrand (South Africa) may also be a source of brannerite, where brannerite is considered as a secondary uranium mineral, it appears as an inclusion in detrital minerals, linings around pyrobitumen nodules and micro veins in gold-bearing horizons [ 9 ]. The occurrence of brannerite in the Central African Orogenic Belt is related to post-magmatic metamorphism, and the minerals associated with brannerite are monazite, uraninite, zircon, albite, calcite, chlorite, apatite, U-silicates and iron oxides [ 10 ]. The Hüttenberg deposit is an Eastern Alps Cretaceous siderite deposit where brannerite exhibits euhedral prismatic crystals and shows the evidence of hydration, metamictization and alteration to anatase [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

The Chemistry, Recrystallization and Thermal Expansion of Brannerite from Akchatau, Kazakhstan

et al. 2023

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Numerous studies expose the potential of brannerite to become a good matrix, concentrating fission products and actinides. Minerals can complement the data collected from the synthetic materials and offer an advantage of a long-time exposure to radiation. Natural metamict brannerite from Akchatau, Kazakhstan, and its annealed sample were studied by EPMA, Raman spectroscopy, TGA, DSC, XRD and HTXRD. The radioactivity of pristine and annealed samples of brannerite was measured. Brannerite from Akchatau is characterized by the absence of significant amounts of REE and yttrium. The studied brannerite regains its structure at a temperature ~650 °C, revealed by the HTXRD and DSC. HTXRD was also performed on the annealed recrystallized brannerite. The thermal expansion for brannerite has been determined for the first time. The brannerite structure expands anisotropically with temperature increase. All the thermal expansion coefficients are positive except for αβ. The decreasing beta parameter indicates a “shear structural deformation“. The angle between the 1st axis of the tensor and the crystallographic a axis decreases with the increase of the temperature. The structure expands mostly in the α11 direction, approaching the bisector of the β angle. Brannerite has a low CTE at room temperature—αv = 16 × 10−6 °C−1, which increases up to 39.4 × 10−6 °C−1 at 1100 °C. In general, the thermal stability of brannerite is comparable to that of the other perspective oxide radioactive waste-immobilizing matrices (e.g., Ln2Zr2O7, CePO4, CaTiO3, CaZrTi2O7). The calculated thermal expansion of brannerite and the understanding of its underlying crystal chemical mechanisms may contribute to the behavior prediction of the material (both metamict and crystalline) at high temperatures.

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Uranium mineralization associated with late magmatic ductile to brittle deformation and Na–Ca metasomatism of the Pan-African A-type Zabili syntectonic pluton (Mayo-Kebbi massif, SW Chad)

Cited by 8 publications

References 99 publications

Health risk assessment and statistical analysis of natural radioactivity in the uranium exploration area of Zabili, Chad

Health risk assessment and statistical analysis of natural radioactivity in the uranium exploration area of Zabili, Chad

Polymetallic Uranium Mineralisation in Rohil, Rajasthan, Western India: Insights from Mode of Occurrences, Structural Controls, Alteration Geochemistry and Exploration

The Chemistry, Recrystallization and Thermal Expansion of Brannerite from Akchatau, Kazakhstan

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