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@article{1579199,
author = {Novák, Milan and Chladek, Stepan and Uher, Pavel and Gadas, Petr},
article_location = {Praha},
article_number = {3},
doi = {http://dx.doi.org/10.3190/jgeosci.269},
keywords = {columbite-group minerals; tapiolite; compositional trends; Nb-Ta and Fe-Mn fractionation; granitic pegmatite},
language = {eng},
issn = {1802-6222},
journal = {Journal of Geosciences},
title = {Complex magmatic and subsolidus compositional trends of columbite-tantalite in the beryl-columbite Sejby granitic pegmatite, Czech Republic: role of crystal-structural constraints and associated minerals},
url = {http://www.jgeosci.org/content/jgeosci.269_novak.pdf},
volume = {63},
year = {2018}
}
TY - JOUR
ID - 1579199
AU - Novák, Milan - Chladek, Stepan - Uher, Pavel - Gadas, Petr
PY - 2018
TI - Complex magmatic and subsolidus compositional trends of columbite-tantalite in the beryl-columbite Sejby granitic pegmatite, Czech Republic: role of crystal-structural constraints and associated minerals
JF - Journal of Geosciences
VL - 63
IS - 3
SP - 253-263
EP - 253-263
PB - Česká geologická společnost
SN - 18026222
KW - columbite-group minerals
KW - tapiolite
KW - compositional trends
KW - Nb-Ta and Fe-Mn fractionation
KW - granitic pegmatite
UR - http://www.jgeosci.org/content/jgeosci.269_novak.pdf
L2 - http://www.jgeosci.org/content/jgeosci.269_novak.pdf
N2 - The simply zoned Sejby pegmatite of beryl-columbite subtype is enclosed in migmatitized gneisses - country rocks of the southern part of the Central Moldanubian Plutonic Complex, Bohemian Massif, Czech Republic. The columbite-group minerals (CGM) occur mostly in blocky K-feldspar unit. Primary magmatic CGM [columbite-(Fe)-tantalite-(Fe)], show an interesting compositional and textural evolution. Subhomogeneous cores of columbite-(Fe)-tantalite-(Fe) (A) are surrounded by heterogeneous intermediate zones (B) and (C) with irregular to oscillatory zoning and mutually comparable compositions. Zone (B) contains grains of tapiolite-(Fe) and inclusions of pyrite decomposed into a mixture of secondary jarosite-group minerals. In the next zone (C), irregular Mn-enriched patches occur and in the outermost thin zone (D) CGM exhibit fine oscillatory zoning typically developed at crystal terminations. The late, subsolidus CGM include patchy-zoned Mn-enriched columbite-(Fe) and late columbite-(Fe) veinlets both formed at the expense of their magmatic precursors in the zone C; the veinlets are also present in the zone D. Similar but fine patches and veinlets are developed around jarosite pseudomorphs after pyrite. The compositional evolution of CGM shows a slight increase in Ta/Nb and Mn/Fe in the zones A and B followed by a reverse trend to elevated Nb and Fe in the zone C and, in particular, in the zone D. Complex subsolidus fluid-melt interactions that generated patches and veinlets caused only minor changes in Ta/Nb and slight Mn-enrichment. Tantalum depletion in veins close to jarosite pseudomorphs after pyrite indicates higher mobility of Ta in acidic low-temperature fluids.
ER -
NOVÁK, Milan, Stepan CHLADEK, Pavel UHER a Petr GADAS. Complex magmatic and subsolidus compositional trends of columbite-tantalite in the beryl-columbite Sejby granitic pegmatite, Czech Republic: role of crystal-structural constraints and associated minerals. \textit{Journal of Geosciences}. Praha: Česká geologická společnost, 2018, roč.~63, č.~3, s.~253-263. ISSN~1802-6222. Dostupné z: https://dx.doi.org/10.3190/jgeosci.269.
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