In the absence of funding specifically identified for this strategic research, there has been little progress in obtaining new analytical data during 2018. Priority was given to:

• Completion of documentation of unpublished experiments on lherzolite at pressures to 6 GPa and with variable water contents.
• Completion of data compilation of experimental study which calibrated the olivine+orthopyroxene+clinopyroxene+ilmenite+/-garnet+/-spinel mineral assemblage as a function of P, T, and fO₂.
• Compositions of near-solidus (<5% melt fraction) melts with dissolved C,H,O,N,S at 1-6 Gpa.

The studies continue to demonstrate how a lherzolitic composition for the upper mantle is able to provide an extraordinary range of parental magmas from high-SiO₂ boninites through olivine-rich picrites to alkali-rich, low SiO₂ ankaramites, olivine melilitites and sodic-dolomitic carbonatites. By controlled experiments (P, T, compositional variation of C, H, S, O) on parental magmas, they can be assigned to specific locations in the ‘Plate Tectonic’ cycle. Results from this strategic research underpin interpretations of specific magmatism in the geological record.

Trevor Falloon and David Green continued the application of experimental high pressure, high temperature studies of lherzolite compositions to two fundamental questions:

• The thin plate behaviour (‘Plate Tectonics’) of the Earth’s lithosphere as a consequence of the intersection of local geotherm and the appropriate lherzolite solidus (sensitively dependent on content of H and C and oxidation state, i.e., lherzolite + C, H, O).
• Demonstration that a lherzolitic composition for the upper mantle is able to provide an extraordinary range of parental magmas from high-SiO₂ boninites through olivine-rich picrites to alkali-rich, low SiO₂ ankaramites, olivine melilitites and sodic-dolomitic carbonatites. By controlled experiments (P, T, compositional variation of C, H, S, O) on parental magmas, they can be assigned to specific locations in the ‘Plate Tectonic’ cycle. Results from this strategic research underpin interpretations of specific magmatism in the geological record.