Petrogenesis and Lu–Hf dating of (ultra)mafic rocks from the Kutná Hora Crystalline Complex: implications for the Devonian evolution of the Bohemian Massif

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F20%3A00000137" target="_blank" >RIV/00025798:_____/20:00000137 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/67985831:_____/20:00536923 RIV/00216224:14310/20:00114487 RIV/00216208:11310/20:10422069

Výsledek na webu

<a href="https://academic.oup.com/petrology/article/61/8/egaa075/5871357" target="_blank" >https://academic.oup.com/petrology/article/61/8/egaa075/5871357</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/petrology/egaa075" target="_blank" >10.1093/petrology/egaa075</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Petrogenesis and Lu–Hf dating of (ultra)mafic rocks from the Kutná Hora Crystalline Complex: implications for the Devonian evolution of the Bohemian Massif

Popis výsledku v původním jazyce

Lu–Hf isotope system and Sr–Nd–Hf–Os isotope systematics of mantle rocks is capable to unravel the early processes in collision belts, especially in hot subduction context where Sm–Nd, and U–Pb system in crustal rocks, are prone to resetting due to high temperatures and interaction with melts during exhumation. To improve models of the Devonian-Carboniferous evolution of the Bohemian Massif, we investigated in detail mafic and ultramafic rocks (eclogite, pyroxenite, and peridotite) from the ultrahigh-pressure and ultrahigh-temperature (UHP–UHT) Kutná Hora Crystalline Complex (KHCC: Úhrov, Bečváry, Doubrava, and Spačice localities). Petrography, multiphase solid inclusions, major- and trace element compositions of rocks and minerals, and radiogenic isotopic data document contrasting sources and protoliths as well effects of subduction-related processes for these rocks. TheÚhrov peridotite has a depleted composition corresponding to the suboceanic asthenospheric mantle, whereas Bečváry and Doubrava peridotites represent lithospheric mantle that underwent melt refertilization by basaltic and SiO2-undersaturated melts, respectively. Multiphase solid inclusions enclosed in garnet from Úhrov and Bečváry peridotites represent trapped H2O±CO2-bearing metasomatizing agents and Fe–Ti-rich melts. The KHCC eclogites either formed by high-pressure crystal accumulation from mantle-derived basaltic melts (Úhrov) or represent a fragment of MORB-like gabbroic cumulate (Spačice) and crustal derived material (Doubrava) both metamorphosed at high P–T conditions. The Lu–Hf age of 395 ± 23 Ma obtained for the Úhrov peridotite reflects garnet growth related to burial of the asthenospheric mantle during subduction of the oceanic slab. By contrast, Spačice and Doubrava eclogites yield younger Lu–Hf ages of ~350 and 330 Ma, respectively, representing mixed ages as demonstrated by the strong granulite-facies overprint and trace element zoning in garnet grains. We propose a refined model for the Early Variscan evolution of the Bohemian Massif starting with the subduction of the oceanic crust (Saxothuringian ocean) andassociated oceanic asthenospheric mantle (Úhrov) beneath the Teplá–Barrandian at ≥ 380 Ma, which was responsible for melt refertilization of the associated mantle wedge (Bečváry, Doubrava). This was followed by continental subduction (~370–360 Ma?) accompanied by the oceanic slab break-off and incorporation of the upwelling asthenospheric mantle into the Moldanubian lithospheric mantle and subsequent coeval exhumation of mantle and crustal rocks at ~350–330 Ma.

Název v anglickém jazyce

Petrogenesis and Lu–Hf dating of (ultra)mafic rocks from the Kutná Hora Crystalline Complex: implications for the Devonian evolution of the Bohemian Massif

Popis výsledku anglicky

Lu–Hf isotope system and Sr–Nd–Hf–Os isotope systematics of mantle rocks is capable to unravel the early processes in collision belts, especially in hot subduction context where Sm–Nd, and U–Pb system in crustal rocks, are prone to resetting due to high temperatures and interaction with melts during exhumation. To improve models of the Devonian-Carboniferous evolution of the Bohemian Massif, we investigated in detail mafic and ultramafic rocks (eclogite, pyroxenite, and peridotite) from the ultrahigh-pressure and ultrahigh-temperature (UHP–UHT) Kutná Hora Crystalline Complex (KHCC: Úhrov, Bečváry, Doubrava, and Spačice localities). Petrography, multiphase solid inclusions, major- and trace element compositions of rocks and minerals, and radiogenic isotopic data document contrasting sources and protoliths as well effects of subduction-related processes for these rocks. TheÚhrov peridotite has a depleted composition corresponding to the suboceanic asthenospheric mantle, whereas Bečváry and Doubrava peridotites represent lithospheric mantle that underwent melt refertilization by basaltic and SiO2-undersaturated melts, respectively. Multiphase solid inclusions enclosed in garnet from Úhrov and Bečváry peridotites represent trapped H2O±CO2-bearing metasomatizing agents and Fe–Ti-rich melts. The KHCC eclogites either formed by high-pressure crystal accumulation from mantle-derived basaltic melts (Úhrov) or represent a fragment of MORB-like gabbroic cumulate (Spačice) and crustal derived material (Doubrava) both metamorphosed at high P–T conditions. The Lu–Hf age of 395 ± 23 Ma obtained for the Úhrov peridotite reflects garnet growth related to burial of the asthenospheric mantle during subduction of the oceanic slab. By contrast, Spačice and Doubrava eclogites yield younger Lu–Hf ages of ~350 and 330 Ma, respectively, representing mixed ages as demonstrated by the strong granulite-facies overprint and trace element zoning in garnet grains. We propose a refined model for the Early Variscan evolution of the Bohemian Massif starting with the subduction of the oceanic crust (Saxothuringian ocean) andassociated oceanic asthenospheric mantle (Úhrov) beneath the Teplá–Barrandian at ≥ 380 Ma, which was responsible for melt refertilization of the associated mantle wedge (Bečváry, Doubrava). This was followed by continental subduction (~370–360 Ma?) accompanied by the oceanic slab break-off and incorporation of the upwelling asthenospheric mantle into the Moldanubian lithospheric mantle and subsequent coeval exhumation of mantle and crustal rocks at ~350–330 Ma.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GA18-27454S" target="_blank" >GA18-27454S: Přenos prvků v prostředí hluboké subdukce: doklady z ultravysokotlakých metamorfovaných terénů</a><br>

Návaznosti

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

Rok uplatnění

2020

Kód důvěrnosti údajů

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

Název periodika

Journal of Petrology

ISSN

0022-3530

e-ISSN

—

Svazek periodika

61

Číslo periodika v rámci svazku

8 : egaa075

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

31

Strana od-do

nestránkováno

Kód UT WoS článku

000606291600002

EID výsledku v databázi Scopus

2-s2.0-85099617268