Tourmaline, an indicator of external Mg-contamination of granitic pegmatites from host serpentinite; examples from the Moldanubian Zone, Czech Republic

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F17%3A00095537" target="_blank" >RIV/00216224:14310/17:00095537 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1007/s00710-017-0512-4" target="_blank" >http://dx.doi.org/10.1007/s00710-017-0512-4</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s00710-017-0512-4" target="_blank" >10.1007/s00710-017-0512-4</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Tourmaline, an indicator of external Mg-contamination of granitic pegmatites from host serpentinite; examples from the Moldanubian Zone, Czech Republic

Popis výsledku v původním jazyce

Dominant primary solidus and minor subsolidus tourmalines from a variety of granitic pegmatites enclosed in serpentinites of the Moldanubian Zone, Czech Republic were examined, mainly by electron probe micro-analyser, to reveal the degree of external Mg(Ca)-contamination from their host rocks. The rocks include: (i) homogeneous to slightly heterogeneous nests of plagioclase-tourmaline rocks (group A) of anatectic or metasomatic origin, (ii) subhomogeneous to simply zoned barren pegmatite dikes (group B), and (iii) Li-bearing zoned pegmatite dikes of rare-element class (group C). The plagioclase-tourmaline rocks (group A) show spatial relation to pegmatites of the group B. Mostly black primary tourmalines (dravite, oxy-dravite, uvite, schorl, oxy-schorl, fluor-schorl) show extensive Mg- and Ca-contamination (group A), moderate Mg- and locally minor Ca-contamination (group B plus the locality Věžná I of the group C) and weak Mg-contamination of the tourmaline solely from outermost pegmatite units (group C); tourmalines from internal units of the pegmatites are typically Mg-free. Both Mg- and Ca-contamination events were very likely contemporaneous. The extent of contamination is higher in small and texturally simple plagioclase-tourmaline rocks (group A). Larger and more highly evolved Li-bearing pegmatites (group C) with zoned internal structure show a high degree of undercooling; consequently, rapid crystallization of outer zones with biotite and/or tourmaline depleted melt in almost all Mg and isolated the pegmatite body from further external contamination during solidus crystallisation. The granitic pegmatites (group B and group C) were open to the host serpentinite during early solidus crystallization immediately after emplacement of melt and then in early and/or late subsolidus crystallization (hydrothermal stage); in plagioclase-tourmaline rocks (group A) the system was likely continuously open to host serpentinite. This study affirms tourmaline as a very useful indicator of external contamination and elevated contents of Mg in tourmaline or in other minerals are the most reliable sign of external contamination in granitic rocks.

Název v anglickém jazyce

Tourmaline, an indicator of external Mg-contamination of granitic pegmatites from host serpentinite; examples from the Moldanubian Zone, Czech Republic

Popis výsledku anglicky

Dominant primary solidus and minor subsolidus tourmalines from a variety of granitic pegmatites enclosed in serpentinites of the Moldanubian Zone, Czech Republic were examined, mainly by electron probe micro-analyser, to reveal the degree of external Mg(Ca)-contamination from their host rocks. The rocks include: (i) homogeneous to slightly heterogeneous nests of plagioclase-tourmaline rocks (group A) of anatectic or metasomatic origin, (ii) subhomogeneous to simply zoned barren pegmatite dikes (group B), and (iii) Li-bearing zoned pegmatite dikes of rare-element class (group C). The plagioclase-tourmaline rocks (group A) show spatial relation to pegmatites of the group B. Mostly black primary tourmalines (dravite, oxy-dravite, uvite, schorl, oxy-schorl, fluor-schorl) show extensive Mg- and Ca-contamination (group A), moderate Mg- and locally minor Ca-contamination (group B plus the locality Věžná I of the group C) and weak Mg-contamination of the tourmaline solely from outermost pegmatite units (group C); tourmalines from internal units of the pegmatites are typically Mg-free. Both Mg- and Ca-contamination events were very likely contemporaneous. The extent of contamination is higher in small and texturally simple plagioclase-tourmaline rocks (group A). Larger and more highly evolved Li-bearing pegmatites (group C) with zoned internal structure show a high degree of undercooling; consequently, rapid crystallization of outer zones with biotite and/or tourmaline depleted melt in almost all Mg and isolated the pegmatite body from further external contamination during solidus crystallisation. The granitic pegmatites (group B and group C) were open to the host serpentinite during early solidus crystallization immediately after emplacement of melt and then in early and/or late subsolidus crystallization (hydrothermal stage); in plagioclase-tourmaline rocks (group A) the system was likely continuously open to host serpentinite. This study affirms tourmaline as a very useful indicator of external contamination and elevated contents of Mg in tourmaline or in other minerals are the most reliable sign of external contamination in granitic rocks.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10504 - Mineralogy

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Mineralogy and Petrology

ISSN

0930-0708

e-ISSN

—

Svazek periodika

111

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

AT - Rakouská republika

Počet stran výsledku

17

Strana od-do

625-641

Kód UT WoS článku

000407743900013

EID výsledku v databázi Scopus

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