Rapid extensional unroofing of a granite-migmatite dome with relics of high-pressure rocks, the Podolsko complex, Bohemian Massif

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11310%2F17%3A10392426" target="_blank" >RIV/00216208:11310/17:10392426 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/67985831:_____/17:00475313

Výsledek na webu

<a href="https://doi.org/10.1017/S0016756816000030" target="_blank" >https://doi.org/10.1017/S0016756816000030</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1017/S0016756816000030" target="_blank" >10.1017/S0016756816000030</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Rapid extensional unroofing of a granite-migmatite dome with relics of high-pressure rocks, the Podolsko complex, Bohemian Massif

Popis výsledku v původním jazyce

The Podolsko complex, Bohemian Massif, is a high-grade dome that is exposed along the suprastructure-infrastructure boundary of the Variscan orogen and records snapshots of its protracted evolution. The dome is cored by leucocratic migmatites and anatectic granites that enclose relics of high- to ultrahigh-pressure rocks and is mantled by biotite migmatites and paragneisses whose degree of anatexis decreases outwards. Our new U-Pb zircon ages indicate that the leucocratic migmatites were derived from Early Ordovician (c. 480 Ma) felsic igneous crust; the same age is inferred for melting the proto-source of the metapelitic migmatites. The relics of high- to ultrahigh-pressure rocks suggest that at least some portions of the complex witnessed an early Variscan subduction to mantle depths, followed by high-temperature anatexis and syntectonic growth of the Podolsko dome in the middle crust at c. 340-339 Ma. Subsequently, the dome exhumation was accommodated by crustal-scale extensional detachments. Similar c. 340 Ma ages have also been reported from other segments of the Variscan belt, yet the significance of this tectonothermal event remains uncertain. Here we conclude that the 340 Ma age post-dates the high-pressure metamorphism; the high temperatures required to cause the observed isotopic resetting and new growth of zircon were probably caused by heat input from the underlying mantle and, finally, the extensional unroofing of the complex requires a minimum throw of about 8-10 km. We use this as an argument for significant early Carboniferous palaeotopography in the interior of the Variscan orogen.

Název v anglickém jazyce

Rapid extensional unroofing of a granite-migmatite dome with relics of high-pressure rocks, the Podolsko complex, Bohemian Massif

Popis výsledku anglicky

The Podolsko complex, Bohemian Massif, is a high-grade dome that is exposed along the suprastructure-infrastructure boundary of the Variscan orogen and records snapshots of its protracted evolution. The dome is cored by leucocratic migmatites and anatectic granites that enclose relics of high- to ultrahigh-pressure rocks and is mantled by biotite migmatites and paragneisses whose degree of anatexis decreases outwards. Our new U-Pb zircon ages indicate that the leucocratic migmatites were derived from Early Ordovician (c. 480 Ma) felsic igneous crust; the same age is inferred for melting the proto-source of the metapelitic migmatites. The relics of high- to ultrahigh-pressure rocks suggest that at least some portions of the complex witnessed an early Variscan subduction to mantle depths, followed by high-temperature anatexis and syntectonic growth of the Podolsko dome in the middle crust at c. 340-339 Ma. Subsequently, the dome exhumation was accommodated by crustal-scale extensional detachments. Similar c. 340 Ma ages have also been reported from other segments of the Variscan belt, yet the significance of this tectonothermal event remains uncertain. Here we conclude that the 340 Ma age post-dates the high-pressure metamorphism; the high temperatures required to cause the observed isotopic resetting and new growth of zircon were probably caused by heat input from the underlying mantle and, finally, the extensional unroofing of the complex requires a minimum throw of about 8-10 km. We use this as an argument for significant early Carboniferous palaeotopography in the interior of the Variscan orogen.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2017

Kód důvěrnosti údajů

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

Název periodika

Geological Magazine

ISSN

0016-7568

e-ISSN

—

Svazek periodika

154

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

27

Strana od-do

354-380

Kód UT WoS článku

000395444700009

EID výsledku v databázi Scopus

2-s2.0-84957798134