Fig. 4: Effects of partial melt extraction and metasomatism on V abundances in eclogites. | Nature Communications

Fig. 4: Effects of partial melt extraction and metasomatism on V abundances in eclogites.

From: Evidence for oxygen-conserving diamond formation in redox-buffered subducted oceanic crust sampled as eclogite

Fig. 4

a Vanadium abundances (ppm) in reconstructed bulk eclogite xenoliths and DI as a function of normal mid-ocean ridge basalt (NMORB)-normalised Ce/Yb, a proxy for melt depletion and enrichment. Shown for comparison is the modelled trend (yellow box) for partial melt extraction from rutile-eclogite, with a moderate decrease of V abundances at relatively oxidising conditions of ∆logƒO2(FMQ) = 0, similar to the modern ambient mantle72. For ∆logƒO2(FMQ) = −4, at the low end of ƒO2 estimates for eclogite xenoliths, partial melt extraction from eclogite causes an increase in V abundances (modelling parameters and rationale in Methods; Supplementary Table 4). Also shown is the effect of metasomatism, as mediated by crystallisation of a high-temperature pyroxene from a kimberlite melt21 with 100–150 ppm V66; V abundances in the metasomatic clinopyroxene are calculated for various temperature and ƒO2 conditions, shown with grey-blue fields (modelling parameters and rationale in Methods; Supplementary Table 5); reconstructed pre-metasomatic eclogites (Cr2O3 < 0.1 and Ce/YbNMORB < 1) would have 280 ± 140 ppm V. NMORB for normalisation from ref. 60. b V abundances (ppm) in reconstructed bulk eclogite xenoliths as a function of oxygen fugacity relative to the Fayalite-Magnetite-Quartz buffer (∆logƒO2(FMQ); no combined ƒO2-V information available for DI), showing an overall positive correlation (significant, see Table 2). Arrows qualitatively indicate effects of melt metasomatism via clinopyroxene addition under various conditions as shown in a (HFSE-high field-strength elements). c V abundances (ppm) in reconstructed bulk eclogite xenoliths and DI as a function of CaO/SiO2, a proxy for metasomatism by CO2-rich melt49; note samples with anomalous V enrichment are restricted to high ratios (teal-coloured field). Average propagated 1σ uncertainties on V abundances are 29 ppm for xenoliths and 69 ppm for DI (Methods). Data sources in Supplementary Data 1.

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