Re–Os and Lu–Hf isotopic constraints on the formation and age ofmantle pyroxenites from the Bohemian Massif

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F16%3A00000127" target="_blank" >RIV/00025798:_____/16:00000127 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/67985831:_____/16:00459673 RIV/00216208:11310/16:10332779

Výsledek na webu

<a href="http://dx.doi.org/10.1016/j.lithos.2016.03.023" target="_blank" >http://dx.doi.org/10.1016/j.lithos.2016.03.023</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.lithos.2016.03.023" target="_blank" >10.1016/j.lithos.2016.03.023</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Re–Os and Lu–Hf isotopic constraints on the formation and age ofmantle pyroxenites from the Bohemian Massif

Popis výsledku v původním jazyce

We report on the Lu–Hf and Re–Os isotope systematics of a well-characterized suite of spinel and garnet pyroxenites from the Gföhl Unit of the Bohemian Massif (Czech Republic, Austria). Lu–Hf mineral isochrons of three pyroxenites yield undistinguishable values in the range of 336–338 Ma. Similarly, the slope of Re–Os regression for most samples yields an age of 327 ± 31 Ma. These values overlap previously reported Sm–Nd ages on pyroxenites, eclogites and associated peridotites from the Gföhl Unit, suggesting contemporaneous evolution of all these HT–HP rocks. The whole-rock Hf isotopic compositions are highly variable with initial εHf values ranging from −6.4 to +66. Most samples show a negative correlation between bulk rock Sm/Hf and εHf and, when taking into account other characteristics (e.g., high 87Sr/86Sr), this may be explained by the presence of recycled oceanic sediments in the source of the pyroxenite parental melts. A pyroxenite from Horní Kounice has decoupled Hf–Nd systematics with highly radiogenic initial εHf of +66 for a given εNd of +7.8. This decoupling is consistent with the presence of a melt derived from a depleted mantle component with high Lu/Hf. Finally, one sample from Bečváry plots close to the MORB field in Hf–Nd isotope space consistent with its previously proposed origin as metamorphosed oceanic gabbro. Some of the websterites and thinlayered pyroxenites have variable, but high Os concentrations paralleled by low initial γOs. This reflects the interaction of the parental pyroxenitic meltswith a depleted peridotitewall rock. In turn, the radiogenic Os isotope compositions observed inmost pyroxenite samples is best explained by mixing between unradiogenic Os derived from peridotites and a low-Os sedimentary precursor with highly radiogenic 187Os/188Os.

Název v anglickém jazyce

Re–Os and Lu–Hf isotopic constraints on the formation and age ofmantle pyroxenites from the Bohemian Massif

Popis výsledku anglicky

We report on the Lu–Hf and Re–Os isotope systematics of a well-characterized suite of spinel and garnet pyroxenites from the Gföhl Unit of the Bohemian Massif (Czech Republic, Austria). Lu–Hf mineral isochrons of three pyroxenites yield undistinguishable values in the range of 336–338 Ma. Similarly, the slope of Re–Os regression for most samples yields an age of 327 ± 31 Ma. These values overlap previously reported Sm–Nd ages on pyroxenites, eclogites and associated peridotites from the Gföhl Unit, suggesting contemporaneous evolution of all these HT–HP rocks. The whole-rock Hf isotopic compositions are highly variable with initial εHf values ranging from −6.4 to +66. Most samples show a negative correlation between bulk rock Sm/Hf and εHf and, when taking into account other characteristics (e.g., high 87Sr/86Sr), this may be explained by the presence of recycled oceanic sediments in the source of the pyroxenite parental melts. A pyroxenite from Horní Kounice has decoupled Hf–Nd systematics with highly radiogenic initial εHf of +66 for a given εNd of +7.8. This decoupling is consistent with the presence of a melt derived from a depleted mantle component with high Lu/Hf. Finally, one sample from Bečváry plots close to the MORB field in Hf–Nd isotope space consistent with its previously proposed origin as metamorphosed oceanic gabbro. Some of the websterites and thinlayered pyroxenites have variable, but high Os concentrations paralleled by low initial γOs. This reflects the interaction of the parental pyroxenitic meltswith a depleted peridotitewall rock. In turn, the radiogenic Os isotope compositions observed inmost pyroxenite samples is best explained by mixing between unradiogenic Os derived from peridotites and a low-Os sedimentary precursor with highly radiogenic 187Os/188Os.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

DD - Geochemie

OECD FORD obor

—

Projekt

—

Návaznosti

V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Rok uplatnění

2016

Kód důvěrnosti údajů

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

Název periodika

Lithos

ISSN

0024-4937

e-ISSN

—

Svazek periodika

256

Číslo periodika v rámci svazku

July

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

13

Strana od-do

197-210

Kód UT WoS článku

000377732500013

EID výsledku v databázi Scopus

—