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Genesis and timing of Mo mineralization in the Mada Ring Complex, north-central Nigeria: insights from whole-rock geochemistry, Nd-Sr isotopes, zircon U-Pb-Hf isotopes, and molybdenite Re-Os systematics.
- Source :
-
Mineralium Deposita . Apr2022, Vol. 57 Issue 4, p601-620. 20p. - Publication Year :
- 2022
-
Abstract
- The genesis and timing of molybdenum (Mo) mineralization in the Mada Ring Complex, north-central Nigeria, have been constrained using a combination of whole-rock elemental geochemistry, Nd-Sr isotopes, zircon U-Pb-Hf isotopes, and molybdenite Re-Os geochronological data. The Mada Ring Complex is one of fifty-three within-plate alkaline ring complexes with economically significant Sn and Nb production from largely alluvial placer deposits in north-central Nigeria. Molybdenum mineralization in the ring complex is dominantly disseminated with minor stockwork veins hosted within biotite granite. Integrated zircon U-Pb and molybdenite Re-Os geochronology constrain initial magma emplacement to between 152 and 151 (± 1) Ma and the Mo-mineralization event to ≤ 150 (± 1) Ma. The granites associated with Mo mineralization are highly silicic and display elevated whole-rock concentrations of Nb, Zr, Y, and REE (except Eu), as well as high 87Rb/86Sr ratios, but low concentrations of Sr, Ba, CaO, MgO, and TiO2, consistent with highly differentiated A-type granites. They yield moderately negative whole-rock εNd(t) (− 5.87 to − 5.47) and zircon εHf(t) (− 4.97 to − 10.06), suggesting that their parental magmas were largely derived from the lower crust with a contribution from the upper mantle. Magmatic oxygen fugacity (ƒO2) of the A-type granites (log FMQ = +1.16), constrained from zircon compositions, is lower than values reported from typical within-plate porphyry molybdenum deposits (log FMQ = +2 to + 3). However, compared to regional Sn ± Nb-mineralized A-type granites, the Mada A-type granites have higher ƒO2 and Ce4+/Ce3+, but are less differentiated. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00264598
- Volume :
- 57
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Mineralium Deposita
- Publication Type :
- Academic Journal
- Accession number :
- 156445875
- Full Text :
- https://doi.org/10.1007/s00126-020-01019-y