Fig. 3: Variation of modal abundance of olivine (volume %) with Fo content.
From: The role of C-O-H-F-Cl fluids in the making of Earth’s continental roots
The Fo contents (Mg/Mg+Fe) of olivines in mantle peridotites are thought to be the most reliable tracer of mantle melting. a Numerical models of mantle melting derived from experimental studies indicate that typical cratonic peridotites have experienced 20% or more melt extraction. Co-variations with the amount of modal olivine show that many of those from the cratonic mantle deviate away from the oceanic trend14. The Kaapvaal craton shows some of the greatest deviations and contrasts with the East Greenland craton102, where there is a close approximation to the trend predicted for melts of peridotite at 3 GPa (red curve). While the deviation of cratonic mantle peridotites away from the oceanic and hypothetical 3 GPa melt residue trends may be explained by high-pressure melting (6 GPa, black curve), the amounts of fusion are implausibly high22. As a consequence, Tomlinson and Kamber18 proposed that the anomalous enrichments in silica can be explained by the melting of a hybrid komatiite-peridotite source (blue curve), which requires lower amounts of melting. Isobaric melt models are after Tomlinson and Kamber18. Data are from this work (Supplementary Data 1), refs. 10,15,52,54,100. b Modal olivine versus Fo content plot together with the melt extraction trend for Phanerozoic mantle (purple arrow)14 coloured for bulk H2O + F contents of cratonic mantle. Data for abyssal peridotites54 and continental off-craton mantle (this work and ref. 52) are shown for comparison.
