Fig. 9
modified from Kempf et al. (2020) is represented by the grey shaded area
Fe3+–Cr3+–Al3+-Ternary diagram of magnetite, Cr-magnetite and Cr–Al-spinel (Additional files 5, 6, 7, 8, 9, 10, 11: Tables S1–7) from zones O–VI. The spinel type minerals show four main populations: low grade oceanic (Vils et al. 2008) and retrograde magnetite (Ol20, Ol16, Ol11b and c), relic oceanic Cr-magnetite cores, prograde Cr-enriched magnetite and prograde Cr–Al-spinel. The blue arrow indicates prograde core to rim compositions of Cr–Al-spinel from chlorite breakdown and the red arrow shows end-member compositions of Al-spinel inclusions in orthopyroxene of zone V (samples Ol9, Ol38) and groundmass grains in sample Ol6, zone VI. Low grade oceanic magnetite compositions are shown by the black "nabla" symbols. Additionally, the mantle compositional array