Transient allanite replacement and prograde to retrograde monazite (re)crystallization in medium-grade metasedimentary rocks from the Orlica-Śnieżnik Dome (Czech Republic/Poland): Textural and geochronological arguments

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F17%3A00000036" target="_blank" >RIV/00025798:_____/17:00000036 - isvavai.cz</a>

Výsledek na webu

<a href="http://www.sciencedirect.com/science?_ob=ShoppingCartURL&_method=add&_eid=1-s2.0-S000925411630643X&_ts=1481629775&md5=105b7a8064143ba4ea2b372c4a9f3a37" target="_blank" >http://www.sciencedirect.com/science?_ob=ShoppingCartURL&_method=add&_eid=1-s2.0-S000925411630643X&_ts=1481629775&md5=105b7a8064143ba4ea2b372c4a9f3a37</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.chemgeo.2016.11.033" target="_blank" >10.1016/j.chemgeo.2016.11.033</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Transient allanite replacement and prograde to retrograde monazite (re)crystallization in medium-grade metasedimentary rocks from the Orlica-Śnieżnik Dome (Czech Republic/Poland): Textural and geochronological arguments

Popis výsledku v původním jazyce

We use textural and geochronological arguments to constrain monazite petrogenesis and the age of metamorphic events in medium-grade metasedimentary rocks from the European Variscan Belt (Orlica-Śnieżnik Dome, Czech Republic/Poland). The relationships between monazite, allanite and other major and accessory phases are characterized for mica schist samples. Garnet porphyroblasts with prograde compositional zoning include allanite in the core and monazite at the rim. Allanite is virtually absent from the matrix; it shows replacement textures involving a cluster of Th±U±Y-rich silicates or phosphates. Monazite, with frequent micro-cracks or trimmed grain boundaries, abounds in themica-rich matrix; it occurs as lone grains close to partially resorbed garnet, apatite or staurolite, and as subhedral and compositionally zoned aggregates associated with allanite and xenotime. 208Pb/232Th ages range from 358 to 299 Ma (±7–8 Ma) regardless of monazite texture or composition. They define a main group at 330–310 Ma, with few older outliers. All observations suggest that a first monazite generation (MnzI) formed via allanite breakdown at prograde to peak P–T conditions (5–7 kbar/575–640 °C). The age of this prograde reaction is, however, preserved by only few domains yielding 360–340Ma. Instead, our results emphasize the importance of retrograde processes which built the dominant age population of 330–310Ma.

Název v anglickém jazyce

Transient allanite replacement and prograde to retrograde monazite (re)crystallization in medium-grade metasedimentary rocks from the Orlica-Śnieżnik Dome (Czech Republic/Poland): Textural and geochronological arguments

Popis výsledku anglicky

We use textural and geochronological arguments to constrain monazite petrogenesis and the age of metamorphic events in medium-grade metasedimentary rocks from the European Variscan Belt (Orlica-Śnieżnik Dome, Czech Republic/Poland). The relationships between monazite, allanite and other major and accessory phases are characterized for mica schist samples. Garnet porphyroblasts with prograde compositional zoning include allanite in the core and monazite at the rim. Allanite is virtually absent from the matrix; it shows replacement textures involving a cluster of Th±U±Y-rich silicates or phosphates. Monazite, with frequent micro-cracks or trimmed grain boundaries, abounds in themica-rich matrix; it occurs as lone grains close to partially resorbed garnet, apatite or staurolite, and as subhedral and compositionally zoned aggregates associated with allanite and xenotime. 208Pb/232Th ages range from 358 to 299 Ma (±7–8 Ma) regardless of monazite texture or composition. They define a main group at 330–310 Ma, with few older outliers. All observations suggest that a first monazite generation (MnzI) formed via allanite breakdown at prograde to peak P–T conditions (5–7 kbar/575–640 °C). The age of this prograde reaction is, however, preserved by only few domains yielding 360–340Ma. Instead, our results emphasize the importance of retrograde processes which built the dominant age population of 330–310Ma.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GA13-16315S" target="_blank" >GA13-16315S: Prográdní metamorfóza, korové ztluštění a spodnokorový tok: nový koncept budování kořene variského orogenu</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2017

Kód důvěrnosti údajů

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

Název periodika

Chemical Geology

ISSN

0009-2541

e-ISSN

—

Svazek periodika

449

Číslo periodika v rámci svazku

January

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

17

Strana od-do

41-57

Kód UT WoS článku

000393001800004

EID výsledku v databázi Scopus

2-s2.0-85007322998