Characteristics of Pegmatite Deposits of Tantalum

Černý, Petr

doi:10.1007/978-3-642-87262-4_8

Cited by 65 publications

(26 citation statements)

References 36 publications

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“…Moreover, it could also have been favoured by a high fluorine activity in the greisen-type dikes, which would have been responsible for a very high Mn/Fe ratio (e.g. Černý and Ercit 1985;Černý et al 1986;Černý 1989). Finally, the secondary assemblage of the columbite-group minerals exhibits a less pronounced enrichment in Mn than the primary one.…”

Section: Chemical Evolution Of the Columbitegroup Mineralsmentioning

confidence: 99%

“…Thus, the increasing fluorine activity would have been the main factor controlling mineral deposition in the greisen-like dikes. These higher F contents would have increased the solubility of the Ta-rich complexes, causing the Ta-and Mn-rich oxides to crystallize during the final consolidation stages of the pegmatite bodies, or even as a consequence of later replacement processes (Černý and Ercit 1985;Černý 1989, 1991.…”

Section: Factors Controlling Melt Fractionation and Ore Depositionmentioning

confidence: 99%

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Oxide minerals in the granitic cupola of the Jálama Batholith, Salamanca, Spain. Part I: accessory Sn, Nb, Ta and Ti minerals in leucogranites, aplites and pegmatites

Llorens¹,

Moro²

2012

J. Geosci.

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Sn-Nb-Ta-Ti oxides occur as accessory minerals in the granitic facies of the External Unit in the Jálama Batholith (Salamanca, Spain) and in the related LCT pegmatite dikes of the rare-element class. Moreover, abundant cassiterite and columbite-group minerals crystallized in the Cruz del Rayo peribatholithic pegmatite dikes, cutting the pre-Ordovician low-grade metasedimentary rocks of the surrounding Schist-Graywacke Complex. Cassiterite, rutile, ilmenite and tantalite-(Fe) occur disseminated in the border facies of the External Unit, especially throughout the tourmaline-bearing leucogranite and the apical aplites. Additionally, cassiterite, rutile and Ta-rich rutile developed locally in the intragranitic pegmatite dikes. Two types of peribatholithic pegmatites can be distinguished at Cruz del Rayo: (i) granite-like pegmatites, with columbite-(Fe) I and II and cassiterite, in which the influence of metasomatic fluids led to formation of the late albite unit and crystallization of tantalite-(Fe), and (ii) greisen-like bodies, which contain high amounts of columbite-(Fe), columbite-(Mn), tantalite-(Mn) I and II as well as cassiterite. The primary oxide assemblage in both types of the peribatholithic pegmatite dikes would have crystallized as a result of magmatic differentiation of the residual melts coming from the Jálama granitic cupola. However, crystallization of the secondary assemblage, richer in Fe and Ta, is interpreted mainly as a consequence of interaction with external fluids coming from the metamorphic host rocks, more or less mixed with meteoric fluids, although partial dissolution and re-precipitation could have played an important role, as well.

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Section: Chemical Evolution Of the Columbitegroup Mineralsmentioning

confidence: 99%

Section: Factors Controlling Melt Fractionation and Ore Depositionmentioning

confidence: 99%

Oxide minerals in the granitic cupola of the Jálama Batholith, Salamanca, Spain. Part I: accessory Sn, Nb, Ta and Ti minerals in leucogranites, aplites and pegmatites

Llorens¹,

Moro²

2012

J. Geosci.

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“…On the contrary, fractionation trends of the Nb-Ta oxide minerals in more evolved berylcolumbite pegmatites also attain Ta-and Mn-rich members of the columbite, tapiolite and wodginite group minerals (Černý et al 1986;Černý 1989;Tindle & Breaks 1998;Novák et al 2000Novák et al , 2003Chudík et al 2011). The textural relationships of the Visole ferrocolumbite indicate its complex origin: a primary magmatic character of the regular oscillatory zones, which are partially replaced by younger, late-magmatic to post-magmatic, secondary irregular zones, presumably originating from dissolution-reprecipitation of the primary ferrocolumbite crystals.…”

Section: Mineral Compositionmentioning

confidence: 99%

Rare-element granitic pegmatite of Miocene age emplaced in UHP rocks from Visole, Pohorje Mountains (Eastern Alps, Slovenia): accessory minerals, monazite and uraninite chemical dating

Uher¹,

Janák²,

Konečný³

et al. 2014

Geologica Carpathica

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Abstract:The granitic pegmatite dike intruded the Cretaceous UHP rocks at Visole, near Slovenska Bistrica, in the Pohorje Mountains (Slovenia). The rock consists mainly of K-feldspar, albite and quartz, subordinate muscovite and biotite, while the accessory minerals include spessartine-almandine, zircon, ferrocolumbite, fluorapatite, monazite-(Ce), uraninite, and magnetite. Compositions of garnet (Sps [48][49] Alm [45][46] Grs +And 3-4 Prp 1.5-2 ), metamict zircon with 3.5 to 7.8 wt. % HfO 2 [atom. 100Hf/(Hf + Zr) = 3.3-7.7] and ferrocolumbite [atom. Mn/(Mn + Fe) = 0.27-0.43, Ta/(Ta + Nb) = 0.03-0.46] indicate a relatively low to medium degree of magmatic fractionation, characteristic of the muscovite -rare-element class or beryl-columbite subtype of the rare-element class pegmatites. Monazite-(Ce) reveals elevated Th and U contents ( ≤ 11 wt. % ThO 2 , ≤ 5 wt. % UO 2 ). The monazite-garnet geothermometer shows a possible precipitation temperature of ~495 ± 30 °C at P~4 to 5 kbar. Chemical U-Th-Pb dating of the monazite yielded a Miocene age (17.2 ± 1.8 Ma), whereas uraninite gave a younger (~14 Ma) age. These ages are comtemporaneous with the main crystallization and emplacement of the Pohorje pluton and adjacent volcanic rocks (20 to 15 Ma), providing the first documented evidence of Neogene granitic pegmatites in the Eastern Alps. Consequently, the Visole pegmatite belongs to the youngest rare-element granitic pegmatite populations in Europe, together with the Paleogene pegmatite occurrences along the Periadriatic (Insubric) Fault System in the Alps and in the Rhodope Massif, as well as the Late Miocene to Pliocene pegmatites in the Tuscany magmatic province (mainly on the Island of Elba).

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“…Nevertheless, tantalite and especially tapiolite are restricted to the strongly evolved, rare-element granitic pegmatites of the LCT-family (according to the classification of Černý and Ercit 2005), where extreme magmatic fractionation enables the production of volatile-and alkali-rich residual melts, essentially enriched in Ta, Hf, Li, Rb, B and other rare lithophile elements (e.g., Černý et al 1985;London 1990London , 2005. The tantalite plus tapiolite assemblage is typical of all types of rare-element granitic pegmatites of the LCT-family; the association of ferrotapiolite with Ferich columbite-tantalite is mostly characteristic of more primitive beryl type populations (e.g., Černý et al 1986;Černý 1989;Novák et al 2000). The tapiolite + Mn-rich columbite-tantalite pairs occur in the most fractionated beryl and especially complex Li, Cs, Ta, F-rich granitic pegmatites worldwide (e.g., Černý et al 1986, 1992aČerný 1989;Novák et al 2000Novák et al , 2003van Lichtervelde et al 2007).…”

Section: The Tantalite-tapiolite Associationmentioning

confidence: 99%

“…The tantalite plus tapiolite assemblage is typical of all types of rare-element granitic pegmatites of the LCT-family; the association of ferrotapiolite with Ferich columbite-tantalite is mostly characteristic of more primitive beryl type populations (e.g., Černý et al 1986;Černý 1989;Novák et al 2000). The tapiolite + Mn-rich columbite-tantalite pairs occur in the most fractionated beryl and especially complex Li, Cs, Ta, F-rich granitic pegmatites worldwide (e.g., Černý et al 1986, 1992aČerný 1989;Novák et al 2000Novák et al , 2003van Lichtervelde et al 2007). …”

Section: The Tantalite-tapiolite Associationmentioning

confidence: 99%

Accessory columbite to tantalite, tapiolite and zircon: products of extreme fractionation in highly peraluminous pegmatitic granite from the Považský Inovec Mountains, Western Carpathians, Slovakia

Chudík

Uher²,

Kohút³

et al. 2012

J. Geosci.

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Accessory Fe-rich columbite-group minerals, tapiolite and Hf-rich zircon occur in Hercynian pegmatitic leucogranite near Duchonka, Považský Inovec Mts., western Slovakia. The host rock represents highly peraluminous and fractionated S-type pegmatitic leucogranite with ASI = 1.27, Eu N /Eu* N = 0.16, Rb/Sr = 7.2, Ta/Nb = 1.1 and Zr/Hf = 21, but not enriched in Li, B, Be or P. Columbite-tantalite, tapiolite and hafnian zircon form discrete crystals, 30 to 350 µm in size, in association with quartz, plagioclase, K-feldspar, muscovite, sillimanite, almandine-spessartine and fluorapatite. Columbite-tantalite crystals show coarse oscillatory zoning, usually with border parts enriched in Ta. Locally, there is a reversal trend of zoning (decrease of Ta towards the border parts), or irregular convoluted zoning as a result of latemagmatic to subsolidus dissolution-reprecipitation. The composition of columbite-tantalite shows a relatively constant Mn/(Mn + Fe) ratio (0.20-0.27, locally 0.35-0.40), but extreme variations of the Ta/(Ta + Nb) ratio (0.18-0.72). Ratios higher than 0.63 plot inside the tantalite-tapiolite miscibility gap. Ferrotapiolite is mainly homogenous and shows relatively consistent compositions with Mn/(Mn + Fe) = 0.03-0.04 and Ta/(Ta + Nb) = 0.88-0.97. Metamict zircon (5 to 120 μm in size) exhibits tiny uraninite inclusions, high Hf contents (6 to 23 wt. % HfO 2 , 0.06-0.23 Hf apfu), and locally elevated P, As and U contents, whereas Y and REE concentrations are low. Unusually widely variable and high Ta/Nb and Hf/Zr ratios in the accessory minerals are probably the product of extreme local Nb-Ta and Zr-Hf fractionation in highly peraluminous granite-pegmatite system.

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Characteristics of Pegmatite Deposits of Tantalum

Cited by 65 publications

References 36 publications

Oxide minerals in the granitic cupola of the Jálama Batholith, Salamanca, Spain. Part I: accessory Sn, Nb, Ta and Ti minerals in leucogranites, aplites and pegmatites

Oxide minerals in the granitic cupola of the Jálama Batholith, Salamanca, Spain. Part I: accessory Sn, Nb, Ta and Ti minerals in leucogranites, aplites and pegmatites

Rare-element granitic pegmatite of Miocene age emplaced in UHP rocks from Visole, Pohorje Mountains (Eastern Alps, Slovenia): accessory minerals, monazite and uraninite chemical dating

Accessory columbite to tantalite, tapiolite and zircon: products of extreme fractionation in highly peraluminous pegmatitic granite from the Považský Inovec Mountains, Western Carpathians, Slovakia

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