Extended Data Fig. 7: Structure of lithospheric keel beneath the eastern Gawler Craton, South Australia81.
From: Building cratonic keels in Precambrian plate tectonics
The upper part of the section is relatively fertile, with high whole-rock Al2O3 but magnesian olivine. It is sharply underlain at about 140 km by a more harzburgite-rich section with lower Al2O3 but also lower XMgOliv. Chromite is more abundant and more Cr-rich in the lower layer, but also has higher mean TiO2, reflecting 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-related85.
