Pyroxene-carbonate reactions in the CaMgSi2O6 ± NaAlSi2O6 + MgCO3 ± Na2CO3 ± K2CO3 system at 3–6 GPa: Implications for partial melting of carbonated peridotite

The reactions between pyroxenes and carbonates have been studied in the CaMgSi 2 O 6 + MgCO 3 (Di + 2Mgs), CaMgSi 2 O 6 + NaAlSi 2 O 6 + 2MgCO 3 (Di + Jd + 2Mgs), CaMgSi 2 O 6 + Na 2 Mg(CO 3 ) 2 (Di + Eit), and CaMgSi 2 O 6 + K 2 Mg(CO 3 ) 2 (Di + K 2 Mg) systems at pressures of 3.0 and 4.5 GPa in the temperature range 850–1300 °C and compared with those established previously at 6.0 GPa. The Di + 2Mgs solidus locates at 1220 °C / 3 GPa and 1400 °C / 6 GPa. Near-solidus melt is carbonatitic with SiO 2