Contrasting petrogenesis of Mg-K and Fe-K granitoids and implications for post-collisional magmatism: Case study from the Late-Archean Matok pluton (Pietersburg block, South Africa)

This model accounts for the differences between Fe-K suites, such as the Matok pluton, and Mg-K suites, such as sanukitoids, the origin of which only requires metasomatized mantle. We propose that the most appropriate geodynamic setting for the interaction between enriched lithospheric and asthenospheric mantle sources is an episode of “lithospheric reworking” (through slab breakoff, retreat or sub-continental mantle delamination) in response to continental collision. Depending on the relative contribution of the two mantle sources in this environment, the resulting magmas can show a wide range of compositions from Fe-K to Mg-K end-members. From a regional point of view, this conclusion supports that the Kaapvaal Craton and the Central Zone of the Limpopo Belt were amalgamated between 2.80 and 2.75 Ga owing to continent-continent collision.