New constraints on the tectonometamorphic evolution of the Erzgebirge orogenic wedge (Saxothuringian Domain, Bohemian Massif)

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F22%3A10457187" target="_blank" >RIV/00216208:11310/22:10457187 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=DuWs-uD6tc" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=DuWs-uD6tc</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1111/jmg.12643" target="_blank" >10.1111/jmg.12643</a>

Jazyk výsledku

angličtina

Název v původním jazyce

New constraints on the tectonometamorphic evolution of the Erzgebirge orogenic wedge (Saxothuringian Domain, Bohemian Massif)

Popis výsledku v původním jazyce

In contrast to well-documented (U)HP rocks of the Erzgebirge crystalline complex (Saxothuringian Domain, Bohemian Massif), the surrounding medium- to low-grade metasediments are scarcely studied, although they provide an important link between deep subduction and mid-crustal processes. To constrain the Variscan evolution from continental subduction to orogenic wedge, the transition from the low-grade phyllites to the footwall medium-grade micaschists was investigated. We used thermodynamic modelling to constrain the P-T conditions of four deformation fabrics (D1-D4) identified by the structural analysis. The studied area was first affected by the M1-D1 event characterized by HP-LT minerals (garnet, chloritoid, phengite, paragonite, and rutile) defining the S1 foliation. The calculated peak P-T conditions for M1 increase from 13 kbar and 520°C in phyllites to 25 kbar and 560°C in micaschists. The corresponding apparent geothermal gradient 6-11°C/km is typical for a subduction environment. The M2-D2 event corresponds to deformation and metamorphic overprint of the previous fabric during partial decompression. The M3-D3 event is mainly developed in micaschists, and the M3 overprint intensifies towards the footwall. It is accompanied by a subhorizontal S3 cleavage characterized by MP-MT assemblage containing biotite, staurolite and ilmenite. The inferred peak P-T conditions for M3 are 5-9 kbar and 595°C representing a barrovian-type geothermal gradient from 17-30°C/km. Finally, all metamorphic fabrics were heterogeneously affected by the low-grade M4-D4 upright folding. The D1-D2 events are interpreted to record the growth and evolution of the Saxothuringian orogenic wedge while its present-day architecture resulted from significant vertical shortening D3 associated with barrovian type M3-metamorphism. This stage corresponds to the ductile thinning of the wedge. A new model is proposed, in which the Erzgebirge part of the Saxothuringian Domain reveals a spectacular example of active margin evolution characterized by (i) formation of accretionary prism, (ii) building of the orogenic wedge by accretion of subducted continental crust, and (iii) its extensional collapse.

Název v anglickém jazyce

New constraints on the tectonometamorphic evolution of the Erzgebirge orogenic wedge (Saxothuringian Domain, Bohemian Massif)

Popis výsledku anglicky

In contrast to well-documented (U)HP rocks of the Erzgebirge crystalline complex (Saxothuringian Domain, Bohemian Massif), the surrounding medium- to low-grade metasediments are scarcely studied, although they provide an important link between deep subduction and mid-crustal processes. To constrain the Variscan evolution from continental subduction to orogenic wedge, the transition from the low-grade phyllites to the footwall medium-grade micaschists was investigated. We used thermodynamic modelling to constrain the P-T conditions of four deformation fabrics (D1-D4) identified by the structural analysis. The studied area was first affected by the M1-D1 event characterized by HP-LT minerals (garnet, chloritoid, phengite, paragonite, and rutile) defining the S1 foliation. The calculated peak P-T conditions for M1 increase from 13 kbar and 520°C in phyllites to 25 kbar and 560°C in micaschists. The corresponding apparent geothermal gradient 6-11°C/km is typical for a subduction environment. The M2-D2 event corresponds to deformation and metamorphic overprint of the previous fabric during partial decompression. The M3-D3 event is mainly developed in micaschists, and the M3 overprint intensifies towards the footwall. It is accompanied by a subhorizontal S3 cleavage characterized by MP-MT assemblage containing biotite, staurolite and ilmenite. The inferred peak P-T conditions for M3 are 5-9 kbar and 595°C representing a barrovian-type geothermal gradient from 17-30°C/km. Finally, all metamorphic fabrics were heterogeneously affected by the low-grade M4-D4 upright folding. The D1-D2 events are interpreted to record the growth and evolution of the Saxothuringian orogenic wedge while its present-day architecture resulted from significant vertical shortening D3 associated with barrovian type M3-metamorphism. This stage corresponds to the ductile thinning of the wedge. A new model is proposed, in which the Erzgebirge part of the Saxothuringian Domain reveals a spectacular example of active margin evolution characterized by (i) formation of accretionary prism, (ii) building of the orogenic wedge by accretion of subducted continental crust, and (iii) its extensional collapse.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GA17-22207S" target="_blank" >GA17-22207S: Role zděděné architektury kontinentálního okraje na ranně Variskou konvergenci</a><br>

Návaznosti

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

Rok uplatnění

2022

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

40

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

29

Strana od-do

687-715

Kód UT WoS článku

000728748200001

EID výsledku v databázi Scopus

2-s2.0-85117734972