RADKOVÁ, Pavlína, Milan NOVÁK, Jan CEMPÍREK, Stanislav HOUZAR a Radek ŠKODA. Amphibole and pyroxene as indicators of alkaline conditions in banded carbonatite-like marbles from Bližná, Český Krumlov Unit, Moldanubian Zone. Journal of Geosciences. Czech Geological Society, 2021, roč. 66, č. 4, s. 243-262. ISSN 1802-6222. Dostupné z: https://dx.doi.org/10.3190/jgeosci.336.
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Základní údaje
Originální název Amphibole and pyroxene as indicators of alkaline conditions in banded carbonatite-like marbles from Bližná, Český Krumlov Unit, Moldanubian Zone
Autoři RADKOVÁ, Pavlína (703 Slovensko, domácí), Milan NOVÁK (203 Česká republika, domácí), Jan CEMPÍREK (203 Česká republika, domácí), Stanislav HOUZAR a Radek ŠKODA (203 Česká republika, domácí).
Vydání Journal of Geosciences, Czech Geological Society, 2021, 1802-6222.
Další údaje
Originální jazyk angličtina
Typ výsledku Článek v odborném periodiku
Obor 10504 Mineralogy
Stát vydavatele Česká republika
Utajení není předmětem státního či obchodního tajemství
WWW URL
Impakt faktor Impact factor: 1.778
Kód RIV RIV/00216224:14310/21:00119494
Organizační jednotka Přírodovědecká fakulta
Doi http://dx.doi.org/10.3190/jgeosci.336
UT WoS 000738385300008
Klíčová slova anglicky Bohemian Massif; Moldanubian Zone; Český Krumlov Unit; pyroxene; alkali amphibole; carbonatite-like marble
Štítky rivok
Příznaky Mezinárodní význam, Recenzováno
Změnil Změnila: Mgr. Marie Šípková, DiS., učo 437722. Změněno: 31. 1. 2022 16:44.
Anotace
Amphiboles and diopside occur in several distinct mineral assemblages in banded carbonatite-like marbles from the Bližná graphite mine, Český Krumlov Unit, Moldanubian Zone. The carbonatite-like marble is interlayered with dominant ordinary metacarbonates as a single continuous stratabound layer, up to 3-4 m thick. It is enriched in elements typical for carbonatites (REE, Y, Th, Sr, Nb, Zr, and Mo) and contains accessory betafite-pyrochlore and uranothorite along with molybdenite, sulfides (e.g., pyrite, pyrrhotite) and oxides (e.g., magnetite, ilmenite). Detailed study of thin sections in optical microscope and BSE images as well as results of EMPA revealed three distinct mineral assemblages - richterite + forsterite (RF) assemblage (Rht + Fo + Cal ˃ Dol ˃ Phl + Di), Na rich actinolite + diopside (AD) assemblage (Di + Act + Rht + Cal ˃ Phl) and magnesio-hastingsite + diopside (HD) assemblage (Mhst + Di + Cal ˃ Ab + Phl). The distinct amphibole species found within the individual assemblages exhibit complex textural relations and crystallized in several prograde and retrograde stages. The following amphibole species were recognized in the individual assemblages: RF - (richterite > ferri-winchite > tremolite, edenite), AD - (actinolite > ferri-winchite; richterite > ferri-katophorite; magnesio-riebeckite), HD - (magnesio-hastingsite; ferri-winchite, actinolite). They differ especially in Mg/(Mg + Fetot) ratio and concentrations of F. Diopside contains up to 17 mol. % of the aegirine component and albite is Fe, Ba-enriched (≥ 0.69 wt. % BaO and ≥ 0.50 wt. % Fe2O3tot). The composition of amphiboles and pyroxenes indicates the alkaline environment of their formation; unusually high Fe2O3 contents in albite plagioclase have known counterparts in alkaline pegmatites and some carbonatite dykes. The following options of potential origin of the carbonatite-like marble from Bližná are discussed: (i) metacarbonates potentially with Na- and Na,Ca-carbonates and sulfate admixture; (ii) admixture of alkaline volcanodetritic component during carbonate sedimentation; (iii) metamorphosed carbonatites enclosed in ordinary sedimentary metacarbonate; (iv) Na-rich metasomatites characterized by mineral assemblages with Na,Fe,F-enriched amphiboles, diopside with high aegirine component and albite. With regard to the observed mineral assemblages, textures and composition of minerals, we can exclude (i) marine evaporates, whereas the other options (ii), (iii) and (iv) are, in general, possible. The amphiboles observed in the Bližná carbonatite-like marble are unique within the Bohemian Massif and distinctly different from amphiboles found in metacarbonates with evaporite component.
Návaznosti
GA19-05198S, projekt VaVNázev: Greisenizace a albitizace - geologické procesy s potenciálem koncentrovat některé kritické suroviny pro moderní technologie (Akronym: GREISEN)
Investor: Grantová agentura ČR, Greisenizace a albitizace - geologické procesy s potenciálem koncentrovat některé kritické suroviny pro moderní technologie
VytisknoutZobrazeno: 19. 9. 2024 05:31