CO2-Rich Melts in Earth

deep Earth, from lower mantle to crust. We fi rst outline constraints from high-pressure experimental petrology and thermodynamic considerations on their stability, as functions of variables such as pressure (P), temperature (T), and oxygen fugacity ( f O 2 These constraints are then used in the context of different tectonic settings in Earth to infer the presence and nature of carbonate melts in those various locations. vapor at pressures lower than 2 GPa At the redox front, reduced carbon present in the eclogite or peridotite oxidizes to form trace to minor amounts of carbonatitic melt (labeled (1)). carbonatitic melt causes fl uxed partial melting of eclogite and peridotite because the carbonated of peridotite and eclogite are at much lower of of produces of with surrounding subsolidus volatile-free peridotite, and a similar melt-rock reaction as proposed (i) takes place.