Composition, fractionation trend and zoning accretion of the columbite-tantalite group of minerals in the Kenticha rare-metal field (Adola, southern Ethiopia)

Tadesse, Solomon; Desta, Zerihun

doi:10.1016/s0899-5362(97)00010-9

Cited by 21 publications

(10 citation statements)

References 12 publications

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“…Nb-Ta bearing oxide minerals (columbo-tantalite (coltan), pyrochlore) are used to establish fractionation evolution of rare-element granite [4,[22][23][24][25][26][27][28][29]. Geochemical studies of oxides and various silicate minerals, as well as mineral zoning, used rare-metal as trace elements to reconstruct ore fractionation in granitic systems, and to characterize the closed-and open-system during magmatic to hydrothermal evolution [8,10,11,[13][14][15]25,28,[30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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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 D 2 to D 3 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. This paper presents an original geological description of the Mayo Salah leucogranite from the Poli region, North Cameroon ( Figure 2). It provides evidence for the first rare-metal bearing granite that is described in this area through field observations, whole-rock geochemistry, textural features, and Minerals 2018, 8, 188 5 of 36 mineralogy of Nb-Ta oxides-bearing minerals. Combining the geochemical and mineralogical features of the Mayo Salah leucogranite with U-Pb geochronological constraints on associated columbite and monazite minerals will allow for discussing the granite emplacement within the current knowledge of the geodynamic environment in this area during Pan-African times. Geological ContextThe Poli region belongs to the Northern Cameroon domain (NCD) of the Central Africa Fold Belt (CAFB) in Cameroon (Figure 2; [62 -64,67-70,79]). This domain results from the collision between the Sahara metacraton [80,81] and the Adamawa-Yadé domain (AYD). Precambrian terrains of the NCD are made of t...

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Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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“…Different types of compositional zoning in Kenticha granite pegmatite such as oscillatory, patchy and mixed oscillatory has been identified [30]. The oscillatory zoning is developed as result of repetitive variations related to crystal growth processes, concentration of the major elements, segregation of gas-saturated magma and is consistent with the periodic variation in Ta, Nb, Mn and Fe contents.…”

Section: Regional and Compositional Zoningsmentioning

confidence: 85%

“…Regional zoning of series of N-S trending barren to rare-metal enriched granite pegmatites in the area can be classified into five different types of pegmatites based on their geological and geochemical signatures [26] [29] [30]. These are (a) barren pegmatites, (b) Ta-poor pegmatites (Kilkele II and III, and Bupo II), (c) Ta-rich beryl-columbite subtype (Kilkele I and Dermidama), (d) complex spodumene type, and (e) albite spodumene type (Bupo I) ( Figure 2).…”

Section: Regional and Compositional Zoningsmentioning

confidence: 99%

“…The texture of this zoning is manifested by relatively homogeneous core, zoned mantle and faceted border zone. The patchy zoning and other replacement textures of columbite-tantalite are formed by late-coming gaseous-rich chemical fluids resorption and replacement processes [30]. The late generation by replacement processes are relatively rich in Ta and Mn.…”

Section: Regional and Compositional Zoningsmentioning

confidence: 99%

“…530 Ma and temporally related to the post-collisional phase of granitic magmatism at 570 Ma -520 Ma [41]. On the other hand the country/host-rocks are dated ~580 ± 50 Ma -680 ± 30 Ma [30]. The emplacement of Kenticha and Bupo pegmatite is coeval and temporally related to postorogenic granite magmatism [10] [41] [42].…”

Section: Age and Emplacement Of Pegmatitesmentioning

confidence: 99%

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Geology, Geochemistry and Geochronology of the Kenticha Rare Metal Granite Pegmatite, Adola Belt, Southern Ethiopia: A Review

Mohammedyasin¹

2017

IJG

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This work reviews the geology, geochemistry and geochronology and discusses the spatial and temporal relationship of the granite pegmatite and the rare metal mineralization of the Kenticha granite pegmatite, southern Ethiopia using published and unpublished works to give a comprehensive understanding about the formation of the mineral deposit. The Kenticha rare metal pegmatite belt comprises several groups of pegmatites which show a high magmatic fractionation, regional and compositional zoning, mineralogical assemblage, and secondary alterations. The internal zonation shows high degree of evolution from the border to the core zone during crystallization and solidification of the leucogranitic to pegmatitic melt. Tantalum mineralization at Kenticha includes zoned tantalite-(Mn) and columbite-(Mn), as well as microlite, pyrochlore, uranmicrolite, and rare tapiolite, ixiolite/wodginite and Ta-bearing rutile. The tectonic setting of the Kenticha granite pegmatite in the Within Plate Granite (WPG) to syn-Collisional Granite (syn-COLG) suites and probably sourced from extreme fractionation of syn-to late tectonic granites or anatexis process of the metasedimentary rocks in the area. The emplacement of the Kenticha pegmatite was at ca. 530 Ma and temporally related to the post-collisional phase of granitic magmatism at 570 -520 Ma, after the last tectonic stage of east African orogeny during the late stage of Gondwana assembly.

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The Kenticha rare-element pegmatite, Ethiopia: internal differentiation, U–Pb age and Ta mineralization

et al. 2009

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Composition, fractionation trend and zoning accretion of the columbite-tantalite group of minerals in the Kenticha rare-metal field (Adola, southern Ethiopia)

Cited by 21 publications

References 12 publications

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

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

Geology, Geochemistry and Geochronology of the Kenticha Rare Metal Granite Pegmatite, Adola Belt, Southern Ethiopia: A Review

The Kenticha rare-element pegmatite, Ethiopia: internal differentiation, U–Pb age and Ta mineralization

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