Insights from mineral trace chemistry on the origin of NYF and mixed LCT + NYF pegmatites and their mineralization at Mangodara, SW Burkina Faso
In: ISSN: 0026-4598 ; Mineralium Deposita ; https://hal.science/hal-04282164 ; Mineralium Deposita, 2023, 58 (1), pp.75-104. ⟨10.1007/s00126-022-01127-x⟩, 2023
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International audience ; The Mangodara district (southwestern of Burkina Faso, West African Craton) consists of a regional-scale Eburnean dome cored by granitoid-gneisses comprising rafts of migmatitic paragneisses and amphibolites of the Paleoproterozoic Birimian series. The occurrence of rare metal-bearing pegmatites in diffuse contact with these migmatitic and granitoid gneisses suggests that they originated from the segregation of a residual melt of these partially molten hosts. In this paper, we constrain the petrogenetic link between pegmatites and their hosts, and the mechanisms of rare metal fractionation in Lithium-Cesium-Tantalum (LCT) vs Niobium-Yttrium-Fluorine (NYF) petrogenetic signatures by the geochemistry of micas, apatite, columbite-group minerals, garnet, and zircon. Titanite-allanite pegmatites (containing titanite, allanite, epidote, zircon, and apatite as accessory minerals) and their evolved equivalent, apatite-zircon pegmatites (richer in apatite, lower K/Rb and Fe/Mn ratio in biotite but Li-depleted) are poorly mineralized metaluminous pegmatites. They display a continuous evolution trend in K/Rb and Fe/Mn in biotite and similar REE patterns in apatite, which favor an origin by segregation of residual melt within tonalitic-trondhjemitic gneiss in the core of the Mangodara dome. Garnet-columbite pegmatites containing REE-bearing phosphates and Zr-U-Th-bearing metamict minerals are mixed LCT + NYF pegmatites. Their micas, slightly enriched in Li, LREE-rich apatite, and Nb-Ta-U-rich garnet, are consistent with an origin by partial melting of a metasedimentary source, with dehydration of biotite (reservoir of Li, Rb, Nb) and dissolution of apatite-monazite (reservoir of REE). Apatite crystals in one garnet-columbite pegmatite reveal an inherited REE signature typical of apatite-zircon pegmatite, which suggests mingling of a LCT pegmatite-forming melt with the residual melt derived from crystallization of metaluminous pegmatites. Garnet-REE pegmatites, containing ilmenite-pyrophanite and ...
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Insights from mineral trace chemistry on the origin of NYF and mixed LCT + NYF pegmatites and their mineralization at Mangodara, SW Burkina Faso
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Autor/in / Beteiligte Person: | Bonzi, Wilédio Marc-Emile ; van Lichtervelde, Marieke ; Vanderhaeghe, Olivier ; André-Mayer, Anne-Sylvie ; Salvi, Stefano ; Wenmenga, Urbain ; Université Joseph Ki-Zerbo Université de Ouagadougou, Burkina Faso (UJZK) ; Géosciences Environnement Toulouse (GET) ; Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP) ; Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS) ; GeoRessources ; Institut national des sciences de l'Univers (INSU - CNRS)-Centre de recherches sur la géologie des matières premières minérales et énergétiques (CREGU)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS) |
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Zeitschrift: | ISSN: 0026-4598 ; Mineralium Deposita ; https://hal.science/hal-04282164 ; Mineralium Deposita, 2023, 58 (1), pp.75-104. ⟨10.1007/s00126-022-01127-x⟩, 2023 |
Veröffentlichung: | HAL CCSD ; Spinger, 2023 |
Medientyp: | academicJournal |
DOI: | 10.1007/s00126-022-01127-x |
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