Uncoupled U/Pb and REE response in zircon during the transformation of eclogite to mafic and intermediate granulite (Blanský les, Bohemian Massif). Journal of Metamorphc Geology

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F16%3A00000164" target="_blank" >RIV/00025798:_____/16:00000164 - isvavai.cz</a>

Výsledek na webu

<a href="http://onlinelibrary.wiley.com/doi/10.1111/jmg.12193/abstract" target="_blank" >http://onlinelibrary.wiley.com/doi/10.1111/jmg.12193/abstract</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1111/jmg.12193" target="_blank" >10.1111/jmg.12193</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Uncoupled U/Pb and REE response in zircon during the transformation of eclogite to mafic and intermediate granulite (Blanský les, Bohemian Massif). Journal of Metamorphc Geology

Popis výsledku v původním jazyce

An eclogite–mafic granulite occurs as a rare boudin within a felsic kyanite–K-feldspar granulite in a low-strain zone. Its boundary is marked by significant metasomatism–diffusional gain of potassium at the centimetre-scale, and probable infiltration of felsic melt on a larger scale. This converted the eclogite–mafic granulite into an intermediate-composition, ternary-feldspar-bearing granulite. Based on inclusions in garnet, the peak P–T conditions of the original eclogite are 18 kbar at 900 °C, with later matrix re-equilibration at 12 kbar and 950 °C. Four samples from the transition of the eclogite–mafic granulite through to the intermediate granulite were studied. In the eclogite, REE patterns in the garnet core show no Eu anomaly, compatible with crystallization in the absence of plagioclase and consistent with eclogite facies conditions. Towards the rim of garnet, LREE decrease, and a weak negative Eu anomaly appears, reflecting passage into HP granulite facies conditions with plagioclase present. Zircon from the four samples was analysed by LASS. It shows U–Pb ages from 404 to 331Ma, with a peak at 340 Ma corresponding to the likely exhumation of the rocks to 12 kbar. Older ages from zircon with steep HREE patterns indicate the minimum age of the protolith, and ages <360 Ma are interpreted to correspond to the eclogite facies metamorphism. Only some zircon grains 350 Ma have flat HREE patterns, suggesting that these are primarily modified protolith grains, rather than new zircon crystallized in the eclogite- or granulite facies. The metasomatic processes that converted the eclogite–mafic granulite to an intermediate granulite may have facilitated zircon modification as zircon in the intermediate granulite has flat HREE and ages of 340 Ma. The difference between the oldest and youngest ages with flat REE patterns indicates a 16 Ma period of zircon modification in the presence of garnet.

Název v anglickém jazyce

Uncoupled U/Pb and REE response in zircon during the transformation of eclogite to mafic and intermediate granulite (Blanský les, Bohemian Massif). Journal of Metamorphc Geology

Popis výsledku anglicky

An eclogite–mafic granulite occurs as a rare boudin within a felsic kyanite–K-feldspar granulite in a low-strain zone. Its boundary is marked by significant metasomatism–diffusional gain of potassium at the centimetre-scale, and probable infiltration of felsic melt on a larger scale. This converted the eclogite–mafic granulite into an intermediate-composition, ternary-feldspar-bearing granulite. Based on inclusions in garnet, the peak P–T conditions of the original eclogite are 18 kbar at 900 °C, with later matrix re-equilibration at 12 kbar and 950 °C. Four samples from the transition of the eclogite–mafic granulite through to the intermediate granulite were studied. In the eclogite, REE patterns in the garnet core show no Eu anomaly, compatible with crystallization in the absence of plagioclase and consistent with eclogite facies conditions. Towards the rim of garnet, LREE decrease, and a weak negative Eu anomaly appears, reflecting passage into HP granulite facies conditions with plagioclase present. Zircon from the four samples was analysed by LASS. It shows U–Pb ages from 404 to 331Ma, with a peak at 340 Ma corresponding to the likely exhumation of the rocks to 12 kbar. Older ages from zircon with steep HREE patterns indicate the minimum age of the protolith, and ages <360 Ma are interpreted to correspond to the eclogite facies metamorphism. Only some zircon grains 350 Ma have flat HREE patterns, suggesting that these are primarily modified protolith grains, rather than new zircon crystallized in the eclogite- or granulite facies. The metasomatic processes that converted the eclogite–mafic granulite to an intermediate granulite may have facilitated zircon modification as zircon in the intermediate granulite has flat HREE and ages of 340 Ma. The difference between the oldest and youngest ages with flat REE patterns indicates a 16 Ma period of zircon modification in the presence of garnet.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

DB - Geologie a mineralogie

OECD FORD obor

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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)

Rok uplatnění

2016

Kód důvěrnosti údajů

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

Název periodika

Journal of Metamorphic Geology

ISSN

0263-4929

e-ISSN

—

Svazek periodika

34

Číslo periodika v rámci svazku

6

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

22

Strana od-do

551-572

Kód UT WoS článku

000379933900003

EID výsledku v databázi Scopus

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