Figure 5

The dot line shows physically sound P–T locus fulfilling the reaction pargasite + forsterite = Na-phlogopite + 2 diopside + spinel. Marked in blue and in red are the P–T regions geologically incoherent and coherent with (spinel-bearing) mantle lithologies, respectively. The modelled P–T locus crosses at ~ 2.3 GPa/1190 K the geotherm calculated for this study (blue thick line) from the analysis of surface heat flow data and combining seismic tomography gravity data^88,89. This P–T path is slightly “cooler” with respect to the Australian geotherm’s field (grey field) from literature^86,87.