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We have experimentally determined the solidus of an alkali-bearing carbonated peridotite (with 5 wt.% CO₂) between 10 and 20 GPa. Based on K-deficit in all low-temperature runs we assumed that some melt could be present in the low temperature runs and the true solidus of an alkali-bearing carbonated peridotite is placed below 1200 °C. However, based on the disappearance of magnesite and the appearance of the visible quenched melt coexisting with silicate phases, the ‘apparent’ solidus, which may be applicable for peridotite with low alkali contents, was identified. The ‘apparent’ solidus temperature increases from ~1380 °C at 10 GPa to ~1525 °C at 15 GPa and the ‘apparent’ solidus curve becomes almost flat from 15 GPa to 20 GPa, where it is located near 1550 °C. At 10 GPa, the ‘apparent’ solidus of carbonated peridotite is ~550 °C lower than the solidus of CO₂-free natural anhydrous peridotite. The …