Extended Data Fig. 7 | Structure of lithospheric keel beneath the eastern
Gawler Craton, South Australia^81. The upper part of the section is relatively
fertile, with high whole-rock Al 2 O 3 but magnesian olivine. It is sharply underlain
at about 140 km by a more harzburgite-rich section with lower Al 2 O 3 but also
lower XMgOliv. Chromite is more abundant and more Cr-rich in the lower layer, but
also has higher mean TiO 2 , ref lecting the increasing melt-related
metasomatism in this layer towards greater depth. The presence of super-deep
diamonds in the kimberlites suggests that the deeper layer may be
plume-related^85.