Petrogenesis and rare-metal mineralization of the Ririwai alkaline granitoids, north-central Nigeria: mineralogical and geochemical constraints

The Ririwai anorogenic alkaline complex harbours extensive rare metal (Nb-Zr-Sn-Zn) mineralization. However, uncertainty still surrounds their origin and magmatic-hydrothermal processes responsible for their rare metal mineralization. The complex is composed of peralkaline arfvedsonite ± albite-bear...

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Bibliographic Details
Published in:International geology review 2024-07, Vol.66 (13), p.2409-2439
Main Authors: Kamaunji, Vandi Dlama, Wang, Lian-Xun, Chen, Wei, Girei, Musa Bala, Ahmed, Hafizullah Abba, Zhu, Yu-Xiang, Vincent, Victor Ikechukwu, Cao, Liang
Format: Article
Language:English
Subjects:
Amphiboles
Apatite
Biotite
Constraints
Crystallization
Dating
Fayalite
Feldspars
Fluorine
Fractional crystallization
Fractionation
Fractures
Geochronometry
Granite
Harbors
Harbours
Heavy metals
Hydrothermal activity
Iron silicates
Isotopes
Lava
Lead isotopes
Magma
Mass balance
Metals
Mineralization
north-central Nigeria
Peralkaline granite
Petrogenesis
prolonged fractional crystallization
Pyrochlores
Radiometric dating
rare metal mineralization
Ririwai complex
Rocks
Samarium isotopes
Silicates
Zircon
Zirconium
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Summary:The Ririwai anorogenic alkaline complex harbours extensive rare metal (Nb-Zr-Sn-Zn) mineralization. However, uncertainty still surrounds their origin and magmatic-hydrothermal processes responsible for their rare metal mineralization. The complex is composed of peralkaline arfvedsonite ± albite-bearing granites, mildly peralkaline fayalite-bearing granite porphyries, and weakly peraluminous biotite-bearing granites, all of which show diagnostic A 1 -type characteristics. Zircon U-Pb dating reveals emplacement ages between 181.4 ± 0.81 and 188.6 ± 7 Ma for the three rock units. Sm-Nd and Pb isotopes (εNd (t) = -0.6 to −5.4, 206 Pb/ 204 Pb = 17.68-17.93) constrained the Ririwai A-type granites to represent highly fractionated products of enriched mantle-derived magmas. Mass-balance modelling suggests that magma evolution was fuelled by extensive fractional crystallization of 50 ~ 60 vol.% K-feldspar, 30 ~ 35 vol% fayalite, 5 ~ 10 vol.% amphibole, and ~ 5 vol.% apatite under reduced and water-undersaturated (ΔFMQ = -1.55; logfo 2  = -18.63; H 2 O =  1.10) indicate the subsequent effect of hydrothermal processes. Tectonically, reactivated shear fractures and transcurrent faults following lithospheric stresses in a transtensional regime allowed magma uprising and emplacement of A-type granites in the Ririwai complex.
ISSN:0020-6814
1938-2839
DOI:10.1080/00206814.2023.2283875