Diverse mineral assemblages of primary Be minerals from pegmatites of the Třebíč Pluton, Moldanubian Zone, Czech Republic; an effect of early tourmaline crystallisation

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F25%3A10169880" target="_blank" >RIV/00025798:_____/25:10169880 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216224:14310/25:00143385

Výsledek na webu

<a href="https://doi.org/10.1180/mgm.2025.10148" target="_blank" >https://doi.org/10.1180/mgm.2025.10148</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1180/mgm.2025.10148" target="_blank" >10.1180/mgm.2025.10148</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Diverse mineral assemblages of primary Be minerals from pegmatites of the Třebíč Pluton, Moldanubian Zone, Czech Republic; an effect of early tourmaline crystallisation

Popis výsledku v původním jazyce

Crystallisation of the earliest minerals typically affects the composition of minerals subsequently formed, being controlled by their abundance and the compatibility/incompatibility of the relevant elements. Here we have investigated the effects of early tourmaline crystallisation on the formation of primary Be minerals (beryl and helvine-danalite) in metaluminous intragranitic NYF pegmatites of the T &amp; rcaron;eb &amp; iacute;&amp; ccaron; Pluton, Czech Republic. Tourmaline occurs in different textural-paragenetic types: (a) coarse- to medium-grained aggregates; (b) graphic (Tur+Qz) intergrowths; (c) fine-grained nodules (Tur+Qz+Pl+Kfs); (d) tourmaline pseudomorphs after biotite; (e) interstitial tourmaline; and (f) replacing helvine-danalite. The compositions of primary tourmalines (a), (b) and (c) vary from Ca- and Ti-rich Fe-dravite to Mg-poor schorl and dutrowite, and to magnesio-dutrowite, showing low to moderate Al (5.1-6.1 apfu), variable Mg (0.1-1.9 apfu) and Fe (1.3-2.2 apfu), low Mn (&lt;= 0.1 apfu), low to moderate Ca (0.1-0.4 apfu), and high Ti (&lt;= 0.55 apfu). Type (f) secondary tourmaline is poor in Mg, Ca and Ti (all &lt;= 0.07 apfu), but rich in Na (0.64-0.81 apfu), Fe (0.68-2.17 apfu), Mn (0.31-0.80 apfu), Al (6.57-7.61 apfu), and F (0.37-0.58 apfu). Two distinct assemblages of early-formed Be minerals were recognised: the assemblage beryl +/- phenakite occurs in pegmatites with rare interstitial tourmaline (e), whereas the assemblage helvine-danalite +/- phenakite is characteristic of pegmatites with abundant early tourmaline (a). The assemblages of primary Be minerals in the individual pegmatites reflect how crystallisation and abundance of early tourmaline control the origin and composition of successive primary Be minerals. The crystallisation of abundant early-formed tourmaline depletes the residual melt of elements that are incorporated preferentially into the tourmaline structure (Al, Mg, Zn), whereas incompatible Mn accumulates, leading to the formation of Mn-rich helvine-danalite. In contrast, beryl only occurs in pegmatites where early-formed tourmaline is absent. The early crystallisation of tourmaline might thus affect the species and composition of later crystallising minerals.

Název v anglickém jazyce

Diverse mineral assemblages of primary Be minerals from pegmatites of the Třebíč Pluton, Moldanubian Zone, Czech Republic; an effect of early tourmaline crystallisation

Popis výsledku anglicky

Crystallisation of the earliest minerals typically affects the composition of minerals subsequently formed, being controlled by their abundance and the compatibility/incompatibility of the relevant elements. Here we have investigated the effects of early tourmaline crystallisation on the formation of primary Be minerals (beryl and helvine-danalite) in metaluminous intragranitic NYF pegmatites of the T &amp; rcaron;eb &amp; iacute;&amp; ccaron; Pluton, Czech Republic. Tourmaline occurs in different textural-paragenetic types: (a) coarse- to medium-grained aggregates; (b) graphic (Tur+Qz) intergrowths; (c) fine-grained nodules (Tur+Qz+Pl+Kfs); (d) tourmaline pseudomorphs after biotite; (e) interstitial tourmaline; and (f) replacing helvine-danalite. The compositions of primary tourmalines (a), (b) and (c) vary from Ca- and Ti-rich Fe-dravite to Mg-poor schorl and dutrowite, and to magnesio-dutrowite, showing low to moderate Al (5.1-6.1 apfu), variable Mg (0.1-1.9 apfu) and Fe (1.3-2.2 apfu), low Mn (&lt;= 0.1 apfu), low to moderate Ca (0.1-0.4 apfu), and high Ti (&lt;= 0.55 apfu). Type (f) secondary tourmaline is poor in Mg, Ca and Ti (all &lt;= 0.07 apfu), but rich in Na (0.64-0.81 apfu), Fe (0.68-2.17 apfu), Mn (0.31-0.80 apfu), Al (6.57-7.61 apfu), and F (0.37-0.58 apfu). Two distinct assemblages of early-formed Be minerals were recognised: the assemblage beryl +/- phenakite occurs in pegmatites with rare interstitial tourmaline (e), whereas the assemblage helvine-danalite +/- phenakite is characteristic of pegmatites with abundant early tourmaline (a). The assemblages of primary Be minerals in the individual pegmatites reflect how crystallisation and abundance of early tourmaline control the origin and composition of successive primary Be minerals. The crystallisation of abundant early-formed tourmaline depletes the residual melt of elements that are incorporated preferentially into the tourmaline structure (Al, Mg, Zn), whereas incompatible Mn accumulates, leading to the formation of Mn-rich helvine-danalite. In contrast, beryl only occurs in pegmatites where early-formed tourmaline is absent. The early crystallisation of tourmaline might thus affect the species and composition of later crystallising minerals.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/EF16_026%2F0008459" target="_blank" >EF16_026/0008459: Dlouhodobý výzkum geochemických bariér pro ukládání jaderného odpadu</a><br>

Návaznosti

V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Rok uplatnění

2025

Kód důvěrnosti údajů

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

Název periodika

Mineralogical Magazine

ISSN

0026-461X

e-ISSN

1471-8022

Svazek periodika

89

Číslo periodika v rámci svazku

6

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

13

Strana od-do

913-925

Kód UT WoS článku

001645336000019

EID výsledku v databázi Scopus

2-s2.0-105014775442