Eo-Variscan metamorphism in the Bohemian Massif: Thermodynamic modelling and monazite geochronology of gneisses and granulites of the Góry Sowie Massif, SW Poland

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F21%3A00545392" target="_blank" >RIV/67985831:_____/21:00545392 - isvavai.cz</a>

Výsledek na webu

<a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/jmg.12589" target="_blank" >https://onlinelibrary.wiley.com/doi/epdf/10.1111/jmg.12589</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1111/jmg.12589" target="_blank" >10.1111/jmg.12589</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Eo-Variscan metamorphism in the Bohemian Massif: Thermodynamic modelling and monazite geochronology of gneisses and granulites of the Góry Sowie Massif, SW Poland

Popis výsledku v původním jazyce

In the Variscides of central Europe, the tectonothermal history of a few units jointly assigned to the Teplá-Barrandian/Bohemian microplate had already terminated in the Devonian. One of these is the Góry Sowie Massif (GSM, Sudetes, SW Poland), mainly consisting of variably migmatitic gneisses with subordinate granulite and peridotite inserts. The eo-Variscan evolution of the GSM was completed in five tectonothermal stages, however, the timing and pressure–temperature (P–T) conditions of the individual stages remain unclear because isotopic ages overlap within error, and previous P–T estimates have been determined without reference to these ages. Our thermodynamic modelling and LA–ICP–MS U–Pb and electron probe microanalysis (EPMA) U–Th–total Pb monazite geochronology provide new insights into the early Variscan multistage evolution of the GSM. The new P–T–time (t) data show that granulites were metamorphosed concurrently with gneisses but at different depths and temperatures. During subduction of Saxothuringia beneath Teplá-Barrandia at 395–390 Ma, the granulites of crustal provenance experienced high-P–high-T conditions (740–750°C, 17–18 kbar) and came in contact with the overlying mantle. Slab break-off gave rise to decompression from conditions of ~17 kbar/840°C to 11–12 kbar/850–860°C, which continued at 380–370 Ma when the granulites were sheared off and extruded as tectonic slices to lower–middle crustal depths, where gneisses were undergoing metamorphism and migmatization under amphibolite facies conditions. In the gneisses, the oldest monazite date of c. 390 Ma constrains the age of the early tectonometamorphic event D1. Two subsequent events (D2 and D3, sillimanite grade) occurred under conditions of 660–680°C and 5–9 kbar at 380–375 Ma, when, in various parts of the future massif, the gneisses were (re)folded and migmatized due to heat arising from underplated mantle. Isostatic exhumation was accompanied by pegmatite intrusions (D4) at 370 Ma and subsequent orogenic collapse (D5). Concurrently, high temperature conditions (~700°C) promoted a disturbance of the U–Pb system in monazite in some granulites.

Název v anglickém jazyce

Eo-Variscan metamorphism in the Bohemian Massif: Thermodynamic modelling and monazite geochronology of gneisses and granulites of the Góry Sowie Massif, SW Poland

Popis výsledku anglicky

In the Variscides of central Europe, the tectonothermal history of a few units jointly assigned to the Teplá-Barrandian/Bohemian microplate had already terminated in the Devonian. One of these is the Góry Sowie Massif (GSM, Sudetes, SW Poland), mainly consisting of variably migmatitic gneisses with subordinate granulite and peridotite inserts. The eo-Variscan evolution of the GSM was completed in five tectonothermal stages, however, the timing and pressure–temperature (P–T) conditions of the individual stages remain unclear because isotopic ages overlap within error, and previous P–T estimates have been determined without reference to these ages. Our thermodynamic modelling and LA–ICP–MS U–Pb and electron probe microanalysis (EPMA) U–Th–total Pb monazite geochronology provide new insights into the early Variscan multistage evolution of the GSM. The new P–T–time (t) data show that granulites were metamorphosed concurrently with gneisses but at different depths and temperatures. During subduction of Saxothuringia beneath Teplá-Barrandia at 395–390 Ma, the granulites of crustal provenance experienced high-P–high-T conditions (740–750°C, 17–18 kbar) and came in contact with the overlying mantle. Slab break-off gave rise to decompression from conditions of ~17 kbar/840°C to 11–12 kbar/850–860°C, which continued at 380–370 Ma when the granulites were sheared off and extruded as tectonic slices to lower–middle crustal depths, where gneisses were undergoing metamorphism and migmatization under amphibolite facies conditions. In the gneisses, the oldest monazite date of c. 390 Ma constrains the age of the early tectonometamorphic event D1. Two subsequent events (D2 and D3, sillimanite grade) occurred under conditions of 660–680°C and 5–9 kbar at 380–375 Ma, when, in various parts of the future massif, the gneisses were (re)folded and migmatized due to heat arising from underplated mantle. Isostatic exhumation was accompanied by pegmatite intrusions (D4) at 370 Ma and subsequent orogenic collapse (D5). Concurrently, high temperature conditions (~700°C) promoted a disturbance of the U–Pb system in monazite in some granulites.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2021

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

39

Číslo periodika v rámci svazku

6

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

29

Strana od-do

751-779

Kód UT WoS článku

000634390800001

EID výsledku v databázi Scopus

2-s2.0-85103209880