Effects of fluorine on the solubilities of Nb, Ta, Zr and Hf minerals in highly fluxed water-saturated haplogranitic melts

Aseri, Abdullah A.; Linnen, Robert L.; Dong, Xiaohong; Thibault, Yves; Holtz, François

doi:10.1016/j.oregeorev.2014.02.014

Cited by 83 publications

(30 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Fractionation of Nb vs. Ta is commonly observed [3,[36][37][38], with Nb usually highly concentrated in peralkaline granites [39] when Ta is mostly concentrated in peraluminous leucogranites and pegmatites [3,4,22,39,40]. The behaviour of the Nb and Ta elements drastically changes depending on melt composition and/or fluxing elements, like F, Li, P, and B [3,11,38,[41][42][43].…”

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

View full text Add to dashboard Cite

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...

show abstract

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

View full text Add to dashboard Cite

show abstract

“…The transitional zone, however, exhibits an atypical trend compared to the other The TEDI parameter is able to distinguish the Nebo and Bobbejaankop granites, but is unable to differentiate the Lease from the Bobbejaankop granite. The inferred TEDI fractionation trend is replicated with other, more robust, large ion lithophile element (LILE) ratios such as Zr/Hf and K/Rb, which are regarded as effective indices of granite fractionation [57][58][59][60][61]. These fractionation indices proved more effective in distinguishing between the two granites, although the complete differentiation of the Bobbejaankop and Lease granites was similarly unsuccessful.…”

Section: Whole Rock Xrf and Icp-msmentioning

confidence: 72%

“…Similarly, the Nb/Ta parameter is used as an index of fractionation as the ratios should remain broadly similar in an evolving magmatic system [59][60][61][62][63][74][75][76][77]. However, an increase in Ta (decrease in Nb/Ta) is attributed to the involvement of fluorine-rich, autometasomatic, mineralizing and greisenizing fluids [59][60][61][62][63]77]. The Bobbejaankop and Lease granites deviate from the Nb/Ta ratio of the Nebo, displaying an enrichment of Ta, particularly at Zaaiplaats (Figure 16).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluating the Changes from Endogranitic Magmatic to Magmatic-Hydrothermal Mineralization: The Zaaiplaats Tin Granites, Bushveld Igneous Complex, South Africa

et al. 2020

View full text Add to dashboard Cite

The stanniferous granites of the Zaaiplaats Tin Field are part of the A-Type Lebowa Granite Suite, within the greater Bushveld Igneous Complex of northeast South Africa. The tin field comprises three granites: (1) the Nebo, a leucocratic, equigranular biotite granite; (2) The brick-red hypidiomorphic Bobbejaankop granite, which is extensively microclinized with chloritized biotite and characteristic synneusis-textured quartz; and (3) The variably altered roof facies of the Bobbejaankop granite known as the Lease microgranite. The Bobbejaankop and Lease granites were both extensively mined for cassiterite until 1989. The cassiterite is hosted in disseminations, miarolitic cavities, and within large hydrothermal, tourmalinized, and greisenized pipes and lenticular ore-bodies. An extensive petrological and whole-rock XRF and ICP-MS geochemical study, has provided new insight into the magmatic and magmatic-hydrothermal mineralization processes in these granites. Trace elements and Rayleigh Fractionation modelling suggest the sequential fractionation of the Nebo granite magma to be the origin of the Bobbejaankop granite. Incompatible elemental ratios, such as Zr/Hf and Nb/Ta, record the influence of internally derived, F-rich, hydrothermal fluid accumulation within the roof of the Bobbejaankop granite. Thus, the Lease granite resulted from alteration of the partially crystallized Bobbejaankop granite, subsequent to fluid saturation, and the accumulation of a magmatic-hydrothermal, volatile-rich fluid in the granite cupola. The ratio of Nb/Ta, proved effective in distinguishing the magmatic and magmatic-hydrothermal transition within the Bobbejaankop granite. Elemental ratios reveal the differences between pre- and post-fluid saturation in the mineralizing regimes within the same pluton. Thus highlighting the effect that the location and degree of hydrothermal alteration have had on the distribution of endogranitic tin mineralization.

show abstract

“…The high volatile flux is an important phenomenon with regard to easier differentiation, emplacement of melt to the shallow crustal level, formation of various rare-metal accessory mineral phases and increase in the metallogenetic capacity. But the behaviour of the high field strength elements is also strongly controlled by the ASI (molar Al / Na + K) parameter (Aseri et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Accessory minerals and evolution of tin-bearing S-type granites in the western segment of the Gemeric Unit (Western Carpathians)

Broska¹,

Kubiś²

2018

Geologica Carpathica

View full text Add to dashboard Cite

The S-type accessory mineral assemblage of zircon, monazite-(Ce), fluorapatite and tourmaline in the cupolas of Permian granites of the Gemeric Unit underwent compositional changes and increased variability and volume due to intensive volatile flux. The extended S-type accessory mineral assemblage in the apical parts of the granite resulted in the formation of rare-metal granites from in-situ differentiation and includes abundant tourmaline, zircon, fluorapatite, monazite-(Ce), Nb–Ta–W minerals (Nb–Ta rutile, ferrocolumbite, manganocolumbite, ixiolite, Nb–Ta ferberite, hübnerite), cassiterite, topaz, molybdenite, arsenopyrite and aluminophosphates. The rare-metal granites from cupolas in the western segment of the Gemeric Unit represent the topaz–zinnwaldite granites, albitites and greisens. Zircon in these evolved rare-metal Li–F granite cupolas shows a larger xenotime-(Y) component and heterogeneous morphology compared to zircons from deeper porphyritic biotite granites. The zircon Zr/Hfwt ratio in deeper rooted porphyritic granite varies from 29 to 45, where in the differentiated upper granites an increase in Hf content results in a Zr/Hfwt ratio of 5. The cheralite component in monazite from porphyritic granites usually does not exceed 12 mol. %, however, highly evolved upper rare-metal granites have monazites with 14 to 20 mol. % and sometimes > 40 mol. % of cheralite. In granite cupolas, pure secondary fluorapatite is generated by exsolution of P from P-rich alkali feldspar and high P and F contents may stabilize aluminophosphates. The biotite granites contain scattered schorlitic tourmaline, while textural late-magmatic tourmaline is more alkali deficient with lower Ca content. The differentiated granites contain also nodular and dendritic tourmaline aggregations. The product of crystallization of volatile-enriched granite cupolas are not only variable in their accessory mineral assemblage that captures high field strength elements, but also in numerous veins in country rocks that often contain cassiterite and tourmaline. Volatile flux is documented by the tetrad effect via patterns of chondrite normalized REEs (T1,3 value 1.46). In situ differentiation and tectonic activity caused multiple intrusive events of fluid-rich magmas rich in incompatible elements, resulting in the formation of rare-metal phases in granite roofs. The emplacement of volatile-enriched magmas into upper crustal conditions was followed by deeper rooted porphyritic magma portion undergoing second boiling and re-melting to form porphyritic granite or granite-porphyry during its ascent.

show abstract

Effects of fluorine on the solubilities of Nb, Ta, Zr and Hf minerals in highly fluxed water-saturated haplogranitic melts

Cited by 83 publications

References 27 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

Evaluating the Changes from Endogranitic Magmatic to Magmatic-Hydrothermal Mineralization: The Zaaiplaats Tin Granites, Bushveld Igneous Complex, South Africa

Accessory minerals and evolution of tin-bearing S-type granites in the western segment of the Gemeric Unit (Western Carpathians)

Contact Info

Product

Resources

About