Extreme variation and apparent reversal of Nb-Ta fractionation
in columbite-group minerals from the Scheibengraben
beryl-columbite pegmatite, Maršíkov, Czech Republic

J 2003

Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite, Maršíkov, Czech Republic

NOVÁK, Milan, Petr ČERNÝ and Pavel UHER

Basic information

Original name

Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite, Maršíkov, Czech Republic

Authors

NOVÁK, Milan (203 Czech Republic, guarantor), Petr ČERNÝ (124 Canada) and Pavel UHER (703 Slovakia)

Edition

European Journal of Mineralogy, Stuttgart, 2003, 0935-1221

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10500 1.5. Earth and related environmental sciences

Country of publisher

Germany

Confidentiality degree

není předmětem státního či obchodního tajemství

Impact factor

Impact factor: 1.185

RIV identification code

RIV/00216224:14310/03:00009085

Organization unit

Faculty of Science

Keywords in English

Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite; Maršíkov; Czech Republic

Abstract

V originále

Compositional variation in columbite-group minerals was studied from the beryl-columbite pegmatite at Scheibengraben, Maršíkov, Northern Moravia, Czech Republic. The pegmatite consists of five textural-paragenetic units, from the least to the most evolved: volumetrically dominant coarse-grained unit, subordinate graphic and blocky units and a minor cleavelandite unit. Saccharoidal albite unit is rather randomly distributed within the dike. It replaces and/or crosscuts all other units except the cleavelandite unit. Columbite-group minerals are the dominant Nb,Ta-oxide phases in all units. They are associated with other Nb,Ta-oxide minerals: minerals of the pyrochlore subgroup and fersmite in the coarse-grained unit, and minerals of the microlite subgroup, ferrotapiolite and rynersonite in the cleavelandite unit. The extreme Nb-Ta [Ta/(Ta+Nb) = 0.06 to 0.97 (microlite 0.99)] and appreciable Fe-Mn [Mn/(Mn+Fe) = (ferrotapiolite 0.22) 0.35 to 0.90] fractionations in columbite-group minerals differ from those observed in beryl pegmatites examined to date, but they are comparable with those in some highly fractionated, complex, Li-rich pegmatites. High activity of F (facilitated by low contents of B, P and Li in the pegmatite melt) very likely maximized such an extensive Nb-Ta fractionation, over and above differential solubilities of columbite and tantalite in pegmatite melt. The apparent reversal of Nb-Ta and Fe-Mn fractionation found in columbite from the saccharoidal albite unit seems to be an artefact from early units (particularly the coarse-grained one), which were extensively replaced by saccharoidal albite.

Links

IAA3046002, research and development project

Name: Akcesorické minerály Ti, Nb, Ta a W jako indikátory geochemického vývoje magmatických a hydrotermálních systémů v Českém masívu

Investor: Academy of Sciences of the Czech Republic, Accessory minerals of Ti,Nb,Ta and W as indicators of geochemical evolutions in magmatic rocks and related and hydroth. systems of the Bohem. Ma.

MSM 143100004, plan (intention)

Name: Geologické procesy a jejich environmentální vyústění - styk variscid a alpid

Investor: Ministry of Education, Youth and Sports of the CR, Geological Processes and their Environmental Impact - Contact of the Variscides and Alpides

Citovat

NOVÁK, Milan, Petr ČERNÝ and Pavel UHER. Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite, Maršíkov, Czech Republic. European Journal of Mineralogy. Stuttgart, 2003, vol. 15, No 5, p. 565-574. ISSN 0935-1221.

@article{490079,
   author = {Novák, Milan and Černý, Petr and Uher, Pavel},
   article_location = {Stuttgart},
   article_number = {5},
   keywords = {Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite; Maršíkov; Czech Republic},
   language = {eng},
   issn = {0935-1221},
   journal = {European Journal of Mineralogy},
   title = {Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite, Maršíkov, Czech Republic},
   volume = {15},
   year = {2003}
}

TY  - JOUR
ID  - 490079
AU  - Novák, Milan - Černý, Petr - Uher, Pavel
PY  - 2003
TI  - Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite, Maršíkov, Czech Republic
JF  - European Journal of Mineralogy
VL  - 15
IS  - 5
SP  - 565-574
EP  - 565-574
SN  - 09351221
KW  - Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite
KW  - Maršíkov
KW  - Czech Republic
N2  - Compositional variation in columbite-group minerals was studied from the beryl-columbite pegmatite at Scheibengraben, Maršíkov, Northern Moravia, Czech Republic. The pegmatite consists of five textural-paragenetic units, from the least to the most evolved: volumetrically dominant coarse-grained unit, subordinate graphic and blocky units and a minor cleavelandite unit. Saccharoidal albite unit is rather randomly distributed within the dike. It replaces and/or crosscuts all other units except the cleavelandite unit. Columbite-group minerals are the dominant Nb,Ta-oxide phases in all units. They are associated with other Nb,Ta-oxide minerals: minerals of the pyrochlore subgroup and fersmite in the coarse-grained unit, and minerals of the microlite subgroup, ferrotapiolite and rynersonite in the cleavelandite unit. The extreme Nb-Ta [Ta/(Ta+Nb) = 0.06 to 0.97 (microlite 0.99)] and appreciable Fe-Mn [Mn/(Mn+Fe) = (ferrotapiolite 0.22) 0.35 to 0.90] fractionations in columbite-group minerals differ from those observed in beryl pegmatites examined to date, but they are comparable with those in some highly fractionated, complex, Li-rich pegmatites. High activity of F (facilitated by low contents of B, P and Li in the pegmatite melt) very likely maximized such an extensive Nb-Ta fractionation, over and above differential solubilities of columbite and tantalite in pegmatite melt. The apparent reversal of Nb-Ta and Fe-Mn fractionation found in columbite from the saccharoidal albite unit seems to be an artefact from early units (particularly the coarse-grained one), which were extensively replaced by saccharoidal albite.
ER  -

NOVÁK, Milan, Petr ČERNÝ and Pavel UHER. Extreme variation and apparent reversal of Nb-Ta fractionation in columbite-group minerals from the Scheibengraben beryl-columbite pegmatite, Maršíkov, Czech Republic. \textit{European Journal of Mineralogy}. Stuttgart, 2003, vol.~15, No~5, p.~565-574. ISSN~0935-1221.

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