Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon): Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and Monazite

The Mayo Salah pluton, which is located in the North-Cameroon domain of Central African Bold Belt (CAFB), is emplaced as a laccolith in volcano-sedimentary schists of Poli series, and displays features of Rare-metal Granite (RMG). It is made of two main rock groups: (1) the metaluminous barren musco...

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Main Authors: Periclex Martial Fosso Tchunte, Rigobert Tchameni, Anne-Sylvie André-Mayer, Hilaire Somtebda Dakoure, François Turlin, Marc Poujol, Emmanuel Negue Nomo, Alliance Nicaise Saha Fouotsa, Olivier Rouer
Format: Article
Language:English
Published: MDPI AG 2018-04-01
Series:Minerals
Subjects:
Online Access:http://www.mdpi.com/2075-163X/8/5/188
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spelling doaj-a913fc3220cc4a00a97288f9ad1537762020-11-24T21:59:10ZengMDPI AGMinerals2075-163X2018-04-018518810.3390/min8050188min8050188Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon): Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and MonazitePericlex Martial Fosso Tchunte0Rigobert Tchameni1Anne-Sylvie André-Mayer2Hilaire Somtebda Dakoure3François Turlin4Marc Poujol5Emmanuel Negue Nomo6Alliance Nicaise Saha Fouotsa7Olivier Rouer8Department of Earth Sciences, Faculty of Science, University of Ngaoundere, PO Box 454 Ngaoundere, CameroonDepartment of Earth Sciences, Faculty of Science, University of Ngaoundere, PO Box 454 Ngaoundere, CameroonGeoRessources, Université de Lorraine, CNRS, F-54000 Nancy, FranceGeoRessources, Université de Lorraine, CNRS, F-54000 Nancy, FranceGeoRessources, Université de Lorraine, CNRS, F-54000 Nancy, FranceUniversity of Rennes, CNRS, Géosciences Rennes-UMR 6118, F-35000 Rennes, FranceDepartment of Earth Sciences, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, CameroonDepartment of Earth Sciences, Faculty of Science, University of Ngaoundere, PO Box 454 Ngaoundere, CameroonGeoRessources, Université de Lorraine, CNRS, F-54000 Nancy, FranceThe Mayo Salah pluton, which is located in the North-Cameroon domain of Central African Bold Belt (CAFB), is emplaced as a laccolith in volcano-sedimentary schists of Poli series, and displays features of Rare-metal Granite (RMG). It is made of two main rock groups: (1) the metaluminous barren muscovite granite (MsG) and (2) the Nb-Ta bearing peraluminous leucogranite (MsL) which expresses four subtypes. The evolved Rare-element MsL is subalkaline, slightly peraluminous (ASI = 1.01–1.21), and it displays flat REE chondrite-normalized patterns with a strong negative Eu anomaly (Eu/Eu* = 0.02–0.20). It belongs to the peraluminous low phosphorus Rare-element Granites and L-type igneous rocks, as shown by the relatively low Zr/Hf (4.8–14) and Nb/Ta (1.4–9.0) ratios and the positive slope of the Zr-Hf-Nb-Ta profile in spider diagrams. The rare-element-bearing mineral is represented by columbite-group minerals (CGM) and other Nb-Ta-oxides (Nb-rutile and pyrochlore supergroup minerals). The CGM is classified as Mn-columbite, with Ta# and Mn# ratios increasing from core to rim. Two stages of mineralization are identified; the earliest stage (CGM-I) consists in scattered tabular or prismatic euhedral grains that were related to magmatic fractionation. The latest stage (CGM-II) is expressed as a Ta-rich Mn hydrothermal CGM episode represented as rims and/overgrowths around and/or as veinlet crosscutting CGM-I or in cleavage planes of muscovite. The U-Pb dating of columbite and monazite of the Mayo Salah leucogranite indicates a late-Neoproterozoic magmatic-hydrothermal mineralization event from 603.2 ± 5.3 to 581.6 ± 7.2 Ma, as consistent with both late D2 to D3 events that were recorded in the CAFB in Cameroon, and the associated continental collision environment. The Nb-Ta mineralization of the Mayo Salah pluton provides evidence for the presence of RMG in Northern Cameroon of CAFB, and its temporal association with the youngest period of metallogenic epoch of Nb-Ta-ore formation in Africa associated to Pan-African times.http://www.mdpi.com/2075-163X/8/5/188Mayo Salahrare-metal graniteperaluminous leucogranitePan-African Nb-Ta mineralizationmagmatic fractionationU-Pb dating of columbite
collection DOAJ
language English
format Article
sources DOAJ
author Periclex Martial Fosso Tchunte
Rigobert Tchameni
Anne-Sylvie André-Mayer
Hilaire Somtebda Dakoure
François Turlin
Marc Poujol
Emmanuel Negue Nomo
Alliance Nicaise Saha Fouotsa
Olivier Rouer
spellingShingle Periclex Martial Fosso Tchunte
Rigobert Tchameni
Anne-Sylvie André-Mayer
Hilaire Somtebda Dakoure
François Turlin
Marc Poujol
Emmanuel Negue Nomo
Alliance Nicaise Saha Fouotsa
Olivier Rouer
Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon): Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and Monazite
Minerals
Mayo Salah
rare-metal granite
peraluminous leucogranite
Pan-African Nb-Ta mineralization
magmatic fractionation
U-Pb dating of columbite
author_facet Periclex Martial Fosso Tchunte
Rigobert Tchameni
Anne-Sylvie André-Mayer
Hilaire Somtebda Dakoure
François Turlin
Marc Poujol
Emmanuel Negue Nomo
Alliance Nicaise Saha Fouotsa
Olivier Rouer
author_sort Periclex Martial Fosso Tchunte
title Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon): Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and Monazite
title_short Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon): Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and Monazite
title_full Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon): Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and Monazite
title_fullStr Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon): Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and Monazite
title_full_unstemmed Evidence for Nb-Ta Occurrences in the Syn-Tectonic Pan-African Mayo Salah Leucogranite (Northern Cameroon): Constraints from Nb-Ta Oxide Mineralogy, Geochemistry and U-Pb LA-ICP-MS Geochronology on Columbite and Monazite
title_sort evidence for nb-ta occurrences in the syn-tectonic pan-african mayo salah leucogranite (northern cameroon): constraints from nb-ta oxide mineralogy, geochemistry and u-pb la-icp-ms geochronology on columbite and monazite
publisher MDPI AG
series Minerals
issn 2075-163X
publishDate 2018-04-01
description The Mayo Salah pluton, which is located in the North-Cameroon domain of Central African Bold Belt (CAFB), is emplaced as a laccolith in volcano-sedimentary schists of Poli series, and displays features of Rare-metal Granite (RMG). It is made of two main rock groups: (1) the metaluminous barren muscovite granite (MsG) and (2) the Nb-Ta bearing peraluminous leucogranite (MsL) which expresses four subtypes. The evolved Rare-element MsL is subalkaline, slightly peraluminous (ASI = 1.01–1.21), and it displays flat REE chondrite-normalized patterns with a strong negative Eu anomaly (Eu/Eu* = 0.02–0.20). It belongs to the peraluminous low phosphorus Rare-element Granites and L-type igneous rocks, as shown by the relatively low Zr/Hf (4.8–14) and Nb/Ta (1.4–9.0) ratios and the positive slope of the Zr-Hf-Nb-Ta profile in spider diagrams. The rare-element-bearing mineral is represented by columbite-group minerals (CGM) and other Nb-Ta-oxides (Nb-rutile and pyrochlore supergroup minerals). The CGM is classified as Mn-columbite, with Ta# and Mn# ratios increasing from core to rim. Two stages of mineralization are identified; the earliest stage (CGM-I) consists in scattered tabular or prismatic euhedral grains that were related to magmatic fractionation. The latest stage (CGM-II) is expressed as a Ta-rich Mn hydrothermal CGM episode represented as rims and/overgrowths around and/or as veinlet crosscutting CGM-I or in cleavage planes of muscovite. The U-Pb dating of columbite and monazite of the Mayo Salah leucogranite indicates a late-Neoproterozoic magmatic-hydrothermal mineralization event from 603.2 ± 5.3 to 581.6 ± 7.2 Ma, as consistent with both late D2 to D3 events that were recorded in the CAFB in Cameroon, and the associated continental collision environment. The Nb-Ta mineralization of the Mayo Salah pluton provides evidence for the presence of RMG in Northern Cameroon of CAFB, and its temporal association with the youngest period of metallogenic epoch of Nb-Ta-ore formation in Africa associated to Pan-African times.
topic Mayo Salah
rare-metal granite
peraluminous leucogranite
Pan-African Nb-Ta mineralization
magmatic fractionation
U-Pb dating of columbite
url http://www.mdpi.com/2075-163X/8/5/188
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