Multiphase solid inclusions reveal the origin and fate of carbonate-silicate melts in metasomatised peridotite

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F21%3A00119281" target="_blank" >RIV/00216224:14310/21:00119281 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00025798:_____/21:00000218

Výsledek na webu

<a href="https://doi.org/10.1016/j.lithos.2021.106309" target="_blank" >https://doi.org/10.1016/j.lithos.2021.106309</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.lithos.2021.106309" target="_blank" >10.1016/j.lithos.2021.106309</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Multiphase solid inclusions reveal the origin and fate of carbonate-silicate melts in metasomatised peridotite

Popis výsledku v původním jazyce

Orogenic peridotite in ultrahigh-pressure ultrahigh-temperature terranes provides increasingly strong evidence of material transfer in a subduction-zone setting, causing the metasomatism and melting of mantle rocks. Multiphase solid inclusions (MSI) trapped in garnet can provide clues to these processes occurring at great depth. The MSI enclosed in garnet in pyroxenite, lherzolite and harzburgite from a drillcore in the Saxothuringian basement in the Variscan Bohemian Massif are dominated by hornblende, barian mica and carbonate (dolomite and magnesite), and they contain a large variety of other phases, including spinel, clinopyroxene, orthopyroxene, garnet II, apatite, monazite, thorianite, graphite, norsethite and barian feldspar, scheelite and sulfides (e.g., pentlandite). We demonstrate, that the bulk chemical composition of the MSI evolves from the MSI trapped in garnet pyroxenite, which was the source of the metasomatising liquids, to the MSI in the host peridotite. Garnet pyroxenite has a carbonate-silicate composition comparable to kimberlite, and represents a rare example of a low-degree supercritical melt derived from a mixed crust-mantle source frozen in the mantle. Its high-pressure fractional crystallization produced a residual melt, enriched in alkalies (Na, K), highly incompatible elements (LILE – Ba, Sr; Th, U), LREE, Ti, W and volatiles (CO2, Cl, F, P), which is now trapped in the MSI in pyroxenite garnet. The MSI in peridotite reflect changes in the physical and chemical characteristics of the metasomatising medium during its reactive infiltration into peridotite through silicate crystallization and interaction with mantle minerals reflecting the type of rock (lherzolite vs. harzburgite). A change from a more silicic, solute-rich melt to a more diluted carbonate-rich liquid gradually enriched in LILE (K, Ba) and volatiles (CO2, Cl) and LREE fractionation with an increasing degree of fluid evolution coincides with the evolution of kimberlitic melts to carbonatitic melts. The low-viscosity carbonate-rich liquids can migrate far and metasomatise a considerable volume of the rock. Our work demonstrates that the MSI trapped in garnet represent a unique tool to trace the chemical and physical characteristics of the liquids that metasomatise the mantle wedge and their evolution.

Název v anglickém jazyce

Multiphase solid inclusions reveal the origin and fate of carbonate-silicate melts in metasomatised peridotite

Popis výsledku anglicky

Orogenic peridotite in ultrahigh-pressure ultrahigh-temperature terranes provides increasingly strong evidence of material transfer in a subduction-zone setting, causing the metasomatism and melting of mantle rocks. Multiphase solid inclusions (MSI) trapped in garnet can provide clues to these processes occurring at great depth. The MSI enclosed in garnet in pyroxenite, lherzolite and harzburgite from a drillcore in the Saxothuringian basement in the Variscan Bohemian Massif are dominated by hornblende, barian mica and carbonate (dolomite and magnesite), and they contain a large variety of other phases, including spinel, clinopyroxene, orthopyroxene, garnet II, apatite, monazite, thorianite, graphite, norsethite and barian feldspar, scheelite and sulfides (e.g., pentlandite). We demonstrate, that the bulk chemical composition of the MSI evolves from the MSI trapped in garnet pyroxenite, which was the source of the metasomatising liquids, to the MSI in the host peridotite. Garnet pyroxenite has a carbonate-silicate composition comparable to kimberlite, and represents a rare example of a low-degree supercritical melt derived from a mixed crust-mantle source frozen in the mantle. Its high-pressure fractional crystallization produced a residual melt, enriched in alkalies (Na, K), highly incompatible elements (LILE – Ba, Sr; Th, U), LREE, Ti, W and volatiles (CO2, Cl, F, P), which is now trapped in the MSI in pyroxenite garnet. The MSI in peridotite reflect changes in the physical and chemical characteristics of the metasomatising medium during its reactive infiltration into peridotite through silicate crystallization and interaction with mantle minerals reflecting the type of rock (lherzolite vs. harzburgite). A change from a more silicic, solute-rich melt to a more diluted carbonate-rich liquid gradually enriched in LILE (K, Ba) and volatiles (CO2, Cl) and LREE fractionation with an increasing degree of fluid evolution coincides with the evolution of kimberlitic melts to carbonatitic melts. The low-viscosity carbonate-rich liquids can migrate far and metasomatise a considerable volume of the rock. Our work demonstrates that the MSI trapped in garnet represent a unique tool to trace the chemical and physical characteristics of the liquids that metasomatise the mantle wedge and their evolution.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10504 - Mineralogy

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

2021

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

398-399

Číslo periodika v rámci svazku

October

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

25

Strana od-do

106309

Kód UT WoS článku

000684298500004

EID výsledku v databázi Scopus

2-s2.0-85109494948