The phase diagram shows the state of water (H2O ... For comparison: At the core-mantle boundary of the Earth at a depth of approx. 2900 kilometres, temperatures of between 3000-4000 Kelvin ...

An illustrative diagram showing the ancient subducted 'slab' the team resolved at present day. It has a direct impact on the large-scale lowermost mantle structures known as 'superplumes'.