Decoupling of Mg from Sr-Nd isotopic compositions in Variscan subduction-related plutonic rocks from the Bohemian Massif: implications for mantle enrichment processes and genesis of orogenic ultrapotassic magmatic rocks

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985530%3A_____%2F22%3A00557724" target="_blank" >RIV/67985530:_____/22:00557724 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00025798:_____/22:00000132 RIV/00216208:11310/22:10457211

Výsledek na webu

<a href="https://link.springer.com/article/10.1007/s00531-022-02199-w" target="_blank" >https://link.springer.com/article/10.1007/s00531-022-02199-w</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s00531-022-02199-w" target="_blank" >10.1007/s00531-022-02199-w</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Decoupling of Mg from Sr-Nd isotopic compositions in Variscan subduction-related plutonic rocks from the Bohemian Massif: implications for mantle enrichment processes and genesis of orogenic ultrapotassic magmatic rocks

Popis výsledku v původním jazyce

The Moldanubian Zone of the Bohemian Massif was intruded by three Variscan (c. 354-335 Ma) subduction-related plutonic suites. Their mantle sources evolved from CHUR-like (low-K calc-alkaline suite), through slightly enriched (epsilon(346)(Nd)similar to - 3, high-K calc-alkaline suite-HKCA) to strongly enriched (epsilon(337)(Nd)< - 7.5, (ultra-)potassic suite-UK). This evolution has been previously interpreted in terms of Andean-type subduction passing to deep subduction/relamination of the Saxothuringian continental crust, metasomatizing the mantle source of the HKCA and, more significantly, of the UK suite. This is in accord with the heterogeneity of lithospheric mantle fragments (spinel/garnet peridotites, garnet pyroxenites, eclogites, glimmer-ites...) sampled by the high-grade Moldanubian orogenic root. Newly acquired Mg isotopic compositions (delta Mg-26 = - 0.12 to - 0.53 parts per thousand) vary over similarly broad intervals within each suite. Majority of the most magnesian samples fall within the range of local orogenic mantle peridotites (- 0.33 to - 0.29 parts per thousand) or close to the global mantle average (- 0.25 parts per thousand). This implies that the delta Mg-26 of the progressively metasomatized harzburgitic mantle was mostly buffered by the mantle end-member, while its mantle-incompatible elemental/related isotopic (Sr-Nd-Pb) signal was swamped by the crustally derived contribution. The crustal contaminant, source of the metasomatic fluids, had to be dominated by Mg-poor, felsic metaigneous > > elastic metasedimentary material. Subducted carbonates were of limited importance, as recorded by lowered delta Mg-26 values in several mafic UK samples and in a glimmerite vein cutting the peridotites (- 0.44 parts per thousand). The Mg isotopic variation in less magnesian potassic rock types reflects a complex interplay between source heterogeneity, equilibrium fractionation during fractional crystallization, kinetic fractionation due to chemical diffusion during magma mixing and/or AFC-style contamination by carbonate-derived fluids.

Název v anglickém jazyce

Decoupling of Mg from Sr-Nd isotopic compositions in Variscan subduction-related plutonic rocks from the Bohemian Massif: implications for mantle enrichment processes and genesis of orogenic ultrapotassic magmatic rocks

Popis výsledku anglicky

The Moldanubian Zone of the Bohemian Massif was intruded by three Variscan (c. 354-335 Ma) subduction-related plutonic suites. Their mantle sources evolved from CHUR-like (low-K calc-alkaline suite), through slightly enriched (epsilon(346)(Nd)similar to - 3, high-K calc-alkaline suite-HKCA) to strongly enriched (epsilon(337)(Nd)< - 7.5, (ultra-)potassic suite-UK). This evolution has been previously interpreted in terms of Andean-type subduction passing to deep subduction/relamination of the Saxothuringian continental crust, metasomatizing the mantle source of the HKCA and, more significantly, of the UK suite. This is in accord with the heterogeneity of lithospheric mantle fragments (spinel/garnet peridotites, garnet pyroxenites, eclogites, glimmer-ites...) sampled by the high-grade Moldanubian orogenic root. Newly acquired Mg isotopic compositions (delta Mg-26 = - 0.12 to - 0.53 parts per thousand) vary over similarly broad intervals within each suite. Majority of the most magnesian samples fall within the range of local orogenic mantle peridotites (- 0.33 to - 0.29 parts per thousand) or close to the global mantle average (- 0.25 parts per thousand). This implies that the delta Mg-26 of the progressively metasomatized harzburgitic mantle was mostly buffered by the mantle end-member, while its mantle-incompatible elemental/related isotopic (Sr-Nd-Pb) signal was swamped by the crustally derived contribution. The crustal contaminant, source of the metasomatic fluids, had to be dominated by Mg-poor, felsic metaigneous > > elastic metasedimentary material. Subducted carbonates were of limited importance, as recorded by lowered delta Mg-26 values in several mafic UK samples and in a glimmerite vein cutting the peridotites (- 0.44 parts per thousand). The Mg isotopic variation in less magnesian potassic rock types reflects a complex interplay between source heterogeneity, equilibrium fractionation during fractional crystallization, kinetic fractionation due to chemical diffusion during magma mixing and/or AFC-style contamination by carbonate-derived fluids.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

<a href="/cs/project/GA18-24378S" target="_blank" >GA18-24378S: Petrogeneze (ultra-)draselných magmat evropských Variscid – implikace pro vývoj kolizních orogenů a modely krustálního růstu</a><br>

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2022

Kód důvěrnosti údajů

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

Název periodika

International Journal of Earth Sciences

ISSN

1437-3254

e-ISSN

1437-3262

Svazek periodika

111

Číslo periodika v rámci svazku

5

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

28

Strana od-do

1491-1518

Kód UT WoS článku

000801132700001

EID výsledku v databázi Scopus

2-s2.0-85131093140