Crystallisation of trapped carbonate-silicate melts terminating at the carbonated solidus ledge: a record of carbon immobilisation mechanism in the lithospheric mantle

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F24%3A10169211" target="_blank" >RIV/00025798:_____/24:10169211 - isvavai.cz</a>

Alternative codes found

RIV/00216224:14310/24:00139441

Result on the web

<a href="https://doi.org/10.1007/s00410-024-02108-1" target="_blank" >https://doi.org/10.1007/s00410-024-02108-1</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s00410-024-02108-1" target="_blank" >10.1007/s00410-024-02108-1</a>

Result language

angličtina

Original language name

Crystallisation of trapped carbonate-silicate melts terminating at the carbonated solidus ledge: a record of carbon immobilisation mechanism in the lithospheric mantle

Original language description

Orogenic peridotites in the crystalline basement of the northwestern Bohemian Massif contain multiphase solid inclusions (MSI), which are interpreted to be crystallisation products of trapped former carbonate-silicate melts metasomatizing their host rocks. We applied conventional thermobarometry and forward thermodynamic modelling to constrain the P-T evolution ranging from the peak metamorphic conditions of the investigated harzburgite and lherzolite, through entrapment of the melts in the outer parts of garnets, to the (re)-equilibration of the MSI assemblages. The peak conditions of c. 1100 degrees C/4.5-5.5 GPa are recorded by garnet cores and large pyroxene porphyroclasts. The melt entrapment, during which garnet outer parts grew, was associated with influx of the metasomatizing liquids and probably took place during the early stage of the exhumation. Thermodynamic model of amphibole-free MSI assemblage comprising kinoshitalite/Ba-rich phlogopite (approximated by phlogopite in the model), dolomite, magnesite, clinopyroxene, orthopyroxene, garnet and chromite provided robust estimate of P and T of its (re)-equilibration, c. 900-1000 degrees C, 1.8-2.2 GPa. Furthermore, the lack of olivine reflects co-existence of COH fluid with high X(CO2) = CO2/(CO2 + H2O) &gt;= 0.6. Models employing identical P-T-X(CO2) parameters successfully reproduced the other two amphibole-bearing assemblages observed. The modelled stability fields show perfect alignment with a characteristic isobaric segment of the solidus curve of carbonated peridotite. This co-incidence implies that the (re)-equilibration corresponds to the termination of the melt crystallisation once the near-isothermal exhumation path intersected the solidus. Decreased solubility of silicates at the carbonated peridotite &quot;solidus ledge&quot;, inferred from the published experimental data, as well as concentric textures of some MSI indicates sequential crystallisation from the early silicates to late dolomite. The carbonated &quot;solidus ledge&quot; is a relatively narrow boundary in the lithospheric mantle capable of an abrupt immobilisation of fluxing or transported carbonated melts. The investigated rocks are estimated to store approximately 0.02 kg C/m3 (or 6 ppm C) occurring as carbonates in the MSI.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10504 - Mineralogy

Project

<a href="/en/project/GA22-33820S" target="_blank" >GA22-33820S: Multiphase solid inclusions in orogenic peridotites as tracers of metasomatism in collisional orogens</a><br>

Continuities

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

Publication year

2024

Confidentiality

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

Name of the periodical

Contributions to Mineralogy and Petrology

ISSN

0010-7999

e-ISSN

1432-0967

Volume of the periodical

179

Issue of the periodical within the volume

4

Country of publishing house

DE - GERMANY

Number of pages

27

Pages from-to

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UT code for WoS article

001187646000001

EID of the result in the Scopus database

2-s2.0-85188133562