Earth’s Mantle Melting in the Presence of C–O–H–Bearing Fluid - Physics and Chemistry of the Deep Earth - page 41

Fig. 2.3 Mantle PT-profiles to 900 km depth. The gray field shows the range of mantle adiabats with potential
temperatures of 1315-1415 ◦ C. The dashed line K-04 shows the 1400 ◦ C adiabat after Katsura et al . (2004). The
dotted line SD-08 correspond to an average mantle thermal model after Stacey and Davis (2008). Rift (oceanic) and
Craton geotherms are shown after data in Figure 2.2. Numbers show PT-profiles of hottest (1) medium (2) and
coldest (3) subduction slabs stagnant in the transition zone and penetrating into the lower mantle (2a and 3a) based
on estimates of van Keken et al . (2002) and Syracuse et al . (2010) for depths of 50 and 250 km (shown by bars
corresponding to slab surface and slab Moho levels). K-parameters for peak metamorphism in the Kokchetav
massif (see Figure 2.2). Phase boundaries and solidus of dry peridotite are shown after Litasov and Ohtani (2007).

the deepest kimberlite and lamproite melts
are generated (Wyllie & Huang, 1976; Wyllie,
1978, 1987; Green & Wallace, 1988; Wallace
& Green, 1988; Green & Falloon, 1998; Wyllie
& Ryabchikov, 2000). Major melting patterns
and melt compositions were determined in the
system peridotite-H 2 O-CO 2 at pressures of
up to 4-5GPa. The key observations include
(i) carbonatite melts form at the peridotite solidus

in the amphibole-phlogopite stability field, and
(ii) decarbonation reactions of solid or liquid
carbonates with silicates result in the extraction
of CO 2 (Figure 2.5). Green & Falloon (1998)
argued that all types of mantle magma, from
basalts to kimberlites and carbonatites may be
produced by melting of peridotite-H 2 O-CO 2 at
pressures of 2-7GPa. Based on studies of the sys-
tems peridotite-CO 2 and eclogite-CO 2 to 9GPa