Fig. 3.

Ternary plots of garnet compositions (molar proportions of Fe + Mn, Ca, and Mg) for metamorphic rocks of the lower plates of the D’Entrecasteaux Islands core complexes, as compared with detrital garnet compositions from the placer deposit. Garnet compositions from metamorphic rocks are color coded according to their bulk composition and plotted with 90% confidence ellipsoids; data were compiled from refs. 16, 31, 32, 38, 54, and 55 and this study (SI Appendix). The field-labeled felsic gneisses (n = 306) include aluminous gneisses, silicic gneisses, and quartzofeldspathic gneisses (including 03118m and 03115). Superimposed on garnet compositional fields are detrital garnet compositions (this study). Compositions of all detrital garnets (n = 716 spots on 572 garnets) are shown in Left. Garnet compositions corresponding to specific inclusion suites are shown in Center (coesite, cristobalite, kokchetavite, omphacite) and Right (CO₂, carbonate, graphite), as indicated in the legend.