Detail publikace

Contrasting origins of the mixed (NYF + LCT) signature in granitic pegmatites, with examples from the Moldanubian Zone, Czech Republic

NOVÁK, M. ŠKODA, R GADAS, P. KRMÍČEK, L. ČERNÝ, P.

Originální název

Contrasting origins of the mixed (NYF + LCT) signature in granitic pegmatites, with examples from the Moldanubian Zone, Czech Republic

Typ

článek v časopise - ostatní, Jost

Jazyk

angličtina

Originální abstrakt

Two granitic pegmatites with mixed (NYF + LCT) signatures from the Moldanubian Zone, Czech Republic, were examined to determine their origin. On the basis of geological setting, paragenesis, geochemical modeling and chemical composition of rocks and minerals, two contrasting modes of origin were discerned. The Li-bearing (lithium micas + elbaite) Kracovice pegmatite, with "amazonite", samarskite and fergusonite, is the product of the strong fractionation of pegmatite-forming melt derived from the orogenic I-type Třebíč pluton. Geological, petrological, compositional and isotopic data from this ultrapotassic melasyenite–melagranite point to mixing of a mantle-derived magma with (leuco)granitic melt from crustal rocks. The granite–pegmatite system of the Třebíč pluton and the mainly Li-bearing Kracovice pegmatite are typical examples of the mixed (NYF + LCT) petrogenetic family. The contaminated elbaite-subtype pegmatite Bližná I, Český Krumlov Unit, with lithium tourmalines (elbaite, liddicoatite, uvite), primary REE minerals [bastnäsite-(Ce), parisite-(Ce), allanite-(Ce)] and Ca(Mg)-rich minerals (diopside, uvite, titanite), gained its mixed signature through a unique pre-emplacement process involving the external contamination with Ca, Mg and REE of an evolved (LCT) pegmatite-forming melt by distal carbonatite-like marbles with an NYF signature. Despite the clearly mixed-signature mineralogy and geochemistry, the Bližná I pegmatite represents a special type of contaminated LCT pegmatite rather than a member of the mixed family.

Klíčová slova

Li-bearing pegmatites; mixed (NYF + LCT) signature; origin; contamination; mixing test; Moldanubian Zone; Czech Republic

Autoři

NOVÁK, M.; ŠKODA, R; GADAS, P.; KRMÍČEK, L.; ČERNÝ, P.

Rok RIV

2012

Vydáno

1. 8. 2012

Nakladatel

Mineralogical Association of Canada

Místo

Kanada

ISSN

0008-4476

Periodikum

CANADIAN MINERALOGIST

Ročník

50

Číslo

4

Stát

Kanada

Strany od

1077

Strany do

1094

Strany počet

18

BibTex

@article{BUT96110,
  author="NOVÁK, M. and ŠKODA, R and GADAS, P. and KRMÍČEK, L. and ČERNÝ, P.",
  title="Contrasting origins of the mixed (NYF + LCT) signature in granitic pegmatites, with examples from the Moldanubian Zone, Czech Republic",
  journal="CANADIAN MINERALOGIST",
  year="2012",
  volume="50",
  number="4",
  pages="1077--1094",
  issn="0008-4476"
}