<b>Petrological and thermodynamic constraints on carbonate stability in altered oceanic crust subducted to subarc depths: </b><b>Insights </b><b>from carbonate-bearing eclogites in the Western Alps</b>

<b>Table S1.</b> Main minerals with estimated modal proportions and bulk-rock compositions of the studied carbonate-bearing Zermatt-Saas eclogites from the Western Alps.<b>Table S2.</b> Representative laser Raman spectra of fluid inclusions and carbonate minerals.<b>Table S3.</b> Representative mineral compositions of the studied carbonate-bearing Zermatt-Saas eclogites from the Western Alps.<b>Table S4. </b>Compilation of temperature estimates obtained from geothermometry.<b>Table S5. </b>Comparison of initial and remaining CO2 contents in decarbonation modelling of samples T94 and ZS99-5.<b>Table S6. </b>H2O and carbon survival rates, carbon concentrations, and oxygen fugacity during the subduction-exhumation process in samples T94 and ZS99-5.<b>Table S7. </b>Trace element compositions of the studied eclogites.<b>Table S8. </b>Variations of carbon survival rate and oxygen fugacity in T94 and ZS99-5 as a function of Fe3+/ΣFe and added carbon forms (graphite and CO2) during the subduction-exhumation process.<b>Table S9. </b>Variations in remaining CO2 content and carbon survival rate with increasing CaCO3 addition during the subduction-exhumation process for samples T94 and ZS99-5.<b>Table S10. </b>Comparison of H2O and carbon survival rates and carbon concentrations along subduction zone thermal gradients of 205°C/GPa and 235°C/GPa, up to 4 GPa.<b>Table S11. </b>Variations in H2O and carbon survival rates and complete decarbonation temperatures under varying subduction zone thermal gradients at subarc depths with different CaCO3contents (6.09 and 9.21 wt.%).<b>Table S12. </b>Variations in remaining CO2 content with fluid–rock mass ratio during external pure water fluid infiltration and fractionation under different P–T conditions for T94.