High-MgO lavas associated to CFB as indicators of plume-related thermochemical effects: The case of ultra-titaniferous picrite-basalt from the Northern Ethiopian-Yemeni Plateau

A comprehensive petrological and geochemical dataset is reported in order to define the thermo-compositional characteristics of Ti (Fe)-enriched picrite-basalt lavas (HT2, TiO2 3-7 wt%), erupted close to the axial zone of the inferred Afar mantle plume, at the centre of the originally continuous Ethiopian-Yemeni CFB plateau (ca. 30 Ma) which is zonally arranged with progressively lower Ti basalts (HT1, TiO2 2-4 wt%; LT, TiO2 1-3 wt%) toward the periphery. Integrated petrogenetic modelling based on major and trace element analyses of bulk rocks, minerals, and melt inclusions in olivines, as well as Sr-Nd-Pb-He-O isotope compositional variations enables us to make several conclusions. 1) The phase equilibria constraints indicate that HT2 primary picrites were generated at ca. 1570 °C mantle potential temperatures (Tp) in the pressure range 4-5 GPa whereas the HT1 and LT primary melts formed at shallower level (