CONTRASTING ORIGINS OF THE MIXED (NYF plus LCT) SIGNATURE IN GRANITIC PEGMATITES, WITH EXAMPLES FROM THE MOLDANUBIAN ZONE, CZECH REPUBLIC

Logo poskytovatele

Varování

Publikace nespadá pod Ekonomicko-správní fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
Autoři

NOVÁK Milan ŠKODA Radek GADAS Petr KRMÍČEK Lukáš ČERNÝ Petr

Rok publikování 2012
Druh Článek v odborném periodiku
Časopis / Zdroj Canadian Mineralogist
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
Doi http://dx.doi.org/10.3749/canmin.50.4.1077
Obor Geologie a mineralogie
Klíčová slova Li-bearing pegmatites; mixed (NYF plus LCT) signature; origin; contamination; mixing test; Moldanubian Zone; Czech Republic
Popis 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 Trebic 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 Trebic pluton and the mainly Li-bearing Kracovice pegmatite are typical examples of the mixed (NYF + LCT) petrogenetic family. The contaminated elbaite-subtype pegmatite Blizna I, Cesky Krumlov Unit, with lithium tourmalines (elbaite, liddicoatite, uvite), primary REE minerals [bastnasite-(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 Blizna I pegmatite represents a special type of contaminated LCT pegmatite rather than a member of the mixed family.
Související projekty:

Používáte starou verzi internetového prohlížeče. Doporučujeme aktualizovat Váš prohlížeč na nejnovější verzi.