FLÉGR, Tomáš and Jan CEMPÍREK. Chemical evolution of tourmaline in elbaite-subtype pegmatites of the Bohemian Massif. In 9th European Conference on Mineralogy and Spectroscopy, 2019. 2019.
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Basic information
Original name Chemical evolution of tourmaline in elbaite-subtype pegmatites of the Bohemian Massif
Authors FLÉGR, Tomáš (203 Czech Republic, guarantor, belonging to the institution) and Jan CEMPÍREK (203 Czech Republic, belonging to the institution).
Edition 9th European Conference on Mineralogy and Spectroscopy, 2019. 2019.
Other information
Original language English
Type of outcome Conference abstract
Field of Study 10504 Mineralogy
Country of publisher Czech Republic
Confidentiality degree is not subject to a state or trade secret
RIV identification code RIV/00216224:14310/19:00107655
Organization unit Faculty of Science
Keywords in English tourmaline; lithium; boron; elbaite; granitic pegmatite; metasomatism
Tags International impact, Reviewed
Changed by Changed by: doc. Mgr. Jan Cempírek, Ph.D., učo 15719. Changed: 19/9/2019 10:25.
Abstract
Tourmaline supergroup is regarded as a robust and versatile group of minerals, useful as an important tool to record the evolution of magmatic and metamorphic systems. Elbaite subtype of rare-element granitic pegmatites was originally defined from the Moldanubian Zone of the Bohemian Massif. Tourmaline is the dominant Li-bearing mineral; it is typically associated by (typically late-stage) borate minerals and B/beraing silicates, including hambergite, datolite, danburite, boromuscovite, tusionite also B-bearing polylithionite. Early tourmaline commonly belongs to the schorl-elbaite series with typical strong enrichment in Mn (and in some cases F), low vacancy and dominant Na. Schorl occurs in various forms in pegmatites border, wall and intermediate zones; however, elbaite is restricted to irregularly distributed pockets (from few mm to several dm in size) and late veinlets. Elbaite subtype pegmatites exhibits low activity of P, reduced F and high B, documented by presence of late/stage boron-rich minerals: Recent data show that some elbaite subtype pegmatites can feature exceptional variability in chemical evolution of primary and secondary tourmalines, especially in composition of the late-stage, most fractionated generations. Tourmalines of the elbaite subtype pegmatite typically belongs to the alkali group, with minor importance of vacancy and rather scarce Ca, however some examples show exceptional enrichment in vacancy in primary and secondary tourmalines [5]. Influence of Ca is typical in latest stages of tourmaline formation (e. g. Řečice, Rudolfov, Dolní Rožínka), locally reaching composition of fluor-liddicoatite. Late hydrothermal tourmalines may also form in outer pegmatite zones, as recently documented by occurrence of Al – deficit, Fe3+, Ti – rich tourmaline replacing primary biotite. In the Řečice pegmatite, it shows composition close to bosiite, in Dolní Rožínka it is Al-deficient schorl-dravite. Besides the usual evolution of the primary tourmaline (from Mg-, Fe-, to Li,Al,Mn- and Li,Al-rich compositions), the elbaite-subtype pegmatites are therefore characterized by significant B(±F)-rich late-magmatic to hydrothermal stage.
Links
GA17-17276S, research and development projectName: Turmalín - indikátor geologických procesů
Investor: Czech Science Foundation
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