Carboniferous Barrovian to Permian Buchan-type metamorphic cycles in the Mongolian Altai Zone: Implication for pressure cycles in accretionary orogens

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F24%3A10169070" target="_blank" >RIV/00025798:_____/24:10169070 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11310/24:10496214

Výsledek na webu

<a href="https://doi.org/10.1111/jmg.12777" target="_blank" >https://doi.org/10.1111/jmg.12777</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1111/jmg.12777" target="_blank" >10.1111/jmg.12777</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Carboniferous Barrovian to Permian Buchan-type metamorphic cycles in the Mongolian Altai Zone: Implication for pressure cycles in accretionary orogens

Popis výsledku v původním jazyce

In the Altai Accretionary Wedge, several periods of Barrovian- and Buchan-type metamorphic cycles were dated from Ordovician to Permian. However, the timing and link between these cycles are not clear, and their causes are debated. In order to contribute to the understanding of Barrovian- to Buchan-type evolution of the accretionary wedges, we studied an area composed of three parallel belts in the easternmost extremity of the Hovd domain located in Mongolian Altai Zone: garnet gneiss in the north, garnet-staurolite-kyanite schist overprinted by +/- sillimanite +/- cordierite +/- andalusite-bearing assemblages in the centre and garnet-sillimanite gneiss in the south. Petrography, garnet zoning and thermodynamic modelling indicate that the garnet gneiss from the northern belt records burial from similar to 510 degrees C and similar to 3-4 kbar to similar to 600 degrees C and similar to 5 kbar, followed by heating to similar to 660 degrees C and decompression to similar to 4.5 kbar. The garnet-staurolite-kyanite schist from the central belt records burial from similar to 550 degrees C and similar to 3-4.5 kbar to similar to 640-680 degrees C and similar to 7 kbar, followed by decompression to the sillimanite stability field at similar to 650 degrees C and similar to 6 kbar. Crystallization of cordierite, andalusite, late muscovite and chlorite in some samples indicates cooling on decompression to similar to 540 degrees C and similar to 3.5 kbar. In the southern gneiss belt, the garnet-sillimanite gneiss with almost unzoned garnet suggests re-equilibration at similar to 6 kbar and similar to 710 degrees C. In situ U-Pb monazite and xenotime dating carried out inclusions in porphyroblasts and matrix grains revealed Carboniferous and Permian ages. The monazite and xenotime from gneisses of the northern and southern belts record Carboniferous and Permian ages, which are interpreted as Carboniferous crystallization at c. 347 Ma associated with metamorphic peak, followed by Permian (re)crystallization at c. 300 and 283 Ma. In the central belt, rare Carboniferous xenotime grains in a garnet-staurolite-kyanite-andalusite-muscovite schist indicate a possible Carboniferous age of the prograde metamorphism. Predominant ages between c. 280 and 260 Ma recorded by monazite are interpreted as a result of complete recrystallization during an LP metamorphic overprint. The Carboniferous ages from the gneisses can be interpreted as constraining the timing of the exhumation of deep crustal rocks to shallow crustal levels. This event corresponds to the formation of crustal-scale migmatite-magmatite domes in the Mongolian Altai Zone. The prograde Barrovian assemblages in the central schist belt are interpreted as having formed contemporaneously during burial in a synform between the migmatite-magmatite domes. The Permian ages reflect LP-HT metamorphism, best recorded by the Buchan-type assemblages in the central schist belt, and are related to massive heat flux from tectonically mobile deep partially molten crust. Correlation with similar Barrovian- and Buchan-type episodes from the Chinese Altai Zone indicates multiple compressional and extensional events in the upper plate accretionary wedge, probably related to retreating and advancing modes of the subduction zone.

Název v anglickém jazyce

Carboniferous Barrovian to Permian Buchan-type metamorphic cycles in the Mongolian Altai Zone: Implication for pressure cycles in accretionary orogens

Popis výsledku anglicky

In the Altai Accretionary Wedge, several periods of Barrovian- and Buchan-type metamorphic cycles were dated from Ordovician to Permian. However, the timing and link between these cycles are not clear, and their causes are debated. In order to contribute to the understanding of Barrovian- to Buchan-type evolution of the accretionary wedges, we studied an area composed of three parallel belts in the easternmost extremity of the Hovd domain located in Mongolian Altai Zone: garnet gneiss in the north, garnet-staurolite-kyanite schist overprinted by +/- sillimanite +/- cordierite +/- andalusite-bearing assemblages in the centre and garnet-sillimanite gneiss in the south. Petrography, garnet zoning and thermodynamic modelling indicate that the garnet gneiss from the northern belt records burial from similar to 510 degrees C and similar to 3-4 kbar to similar to 600 degrees C and similar to 5 kbar, followed by heating to similar to 660 degrees C and decompression to similar to 4.5 kbar. The garnet-staurolite-kyanite schist from the central belt records burial from similar to 550 degrees C and similar to 3-4.5 kbar to similar to 640-680 degrees C and similar to 7 kbar, followed by decompression to the sillimanite stability field at similar to 650 degrees C and similar to 6 kbar. Crystallization of cordierite, andalusite, late muscovite and chlorite in some samples indicates cooling on decompression to similar to 540 degrees C and similar to 3.5 kbar. In the southern gneiss belt, the garnet-sillimanite gneiss with almost unzoned garnet suggests re-equilibration at similar to 6 kbar and similar to 710 degrees C. In situ U-Pb monazite and xenotime dating carried out inclusions in porphyroblasts and matrix grains revealed Carboniferous and Permian ages. The monazite and xenotime from gneisses of the northern and southern belts record Carboniferous and Permian ages, which are interpreted as Carboniferous crystallization at c. 347 Ma associated with metamorphic peak, followed by Permian (re)crystallization at c. 300 and 283 Ma. In the central belt, rare Carboniferous xenotime grains in a garnet-staurolite-kyanite-andalusite-muscovite schist indicate a possible Carboniferous age of the prograde metamorphism. Predominant ages between c. 280 and 260 Ma recorded by monazite are interpreted as a result of complete recrystallization during an LP metamorphic overprint. The Carboniferous ages from the gneisses can be interpreted as constraining the timing of the exhumation of deep crustal rocks to shallow crustal levels. This event corresponds to the formation of crustal-scale migmatite-magmatite domes in the Mongolian Altai Zone. The prograde Barrovian assemblages in the central schist belt are interpreted as having formed contemporaneously during burial in a synform between the migmatite-magmatite domes. The Permian ages reflect LP-HT metamorphism, best recorded by the Buchan-type assemblages in the central schist belt, and are related to massive heat flux from tectonically mobile deep partially molten crust. Correlation with similar Barrovian- and Buchan-type episodes from the Chinese Altai Zone indicates multiple compressional and extensional events in the upper plate accretionary wedge, probably related to retreating and advancing modes of the subduction zone.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GX19-27682X" target="_blank" >GX19-27682X: Hlavní mechanismy periferálního kontinentálního růstu během superkontinentálního cyklu</a><br>

Návaznosti

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

Rok uplatnění

2024

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

1525-1314

Svazek periodika

42

Číslo periodika v rámci svazku

7

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

55

Strana od-do

979-1033

Kód UT WoS článku

001255970300001

EID výsledku v databázi Scopus

2-s2.0-85197152054