Fig. 4.
Lithophile trace element and sulfur isotopic compositions of the studied glass (formerly melt) inclusions. a Primitive mantle-normalised66 lithophile trace element abundances (averages, Supplementary Table 13) in the glasses28,29 of Kamchatka LT inclusions (cyan pattern), MP (green pattern) and vein MI (pink pattern) compared to MORB46,48,49 (black pattern). Sulfur is always enriched in comparison with lithophile trace elements as incompatible as S2− (e.g. Dy, ref. 67) in the inclusion glasses. This further suggests that S was enriched and/or oxidised in the mantle sources of the inclusion parental melts, since S6+ is much more soluble than S2− in silicate liquids8,58. b A δ34S (‰) vs. S content (p.p.m.) plot for MP in this study (green dots, Supplementary Table 11), compared with DMM estimates46,48,49 (orange field) and MORB data48,49 (black field). The error bars represent the 2σ analytical uncertainty on the δ34S values reported in this study (Supplementary Table 11). Also shown are high-pressure slab rocks15 (light and dark blue fields) and black mixing lines between a DMM source and agents derived from subducted serpentinite (dark blue stars), as inferred from high-pressure slab rocks15, with variable bulk S contents (260–5200 p.p.m., exclusively present as sulfate). These variable bulk S contents are calculated to account for different dilution factors of S in agents derived from subducted serpentinite, depending on whether these agents contain only H2O and S (5200 p.p.m. S) or more components ( < 5200 p.p.m. S). For this purpose, H2O (5 wt%) and S (260 p.p.m.) abundances inferred to be lost by subducted serpentinite15 are used. The composition of the volatile fraction in the parental melts of MP (S abundances and δ34S) is consistent with mixing between DMM and subducted serpentinite-derived agents containing ≥ 1000 p.p.m. sulfate (SO42−). Given that the mantle source protoliths of the MP parental melts are more depleted than DMM (a), 1000 p.p.m. S in agents derived from subducted serpentinite likely represents a lower bound and the mixing lines could be shifted to the left in b (‘melt depletion’, orange arrow). Note that all MP for which S data are presented here are unheated