Fig. 4: Schematic diagrams illustrating changes in evolved crust-forming processes and lithospheric architecture between the Hadean and Archaean. | Nature Communications

Fig. 4: Schematic diagrams illustrating changes in evolved crust-forming processes and lithospheric architecture between the Hadean and Archaean.

From: Crustal rejuvenation stabilised Earth’s first cratons

Fig. 4

The Hadean crust is predominantly mafic–ultramafic with minor evolved melts formed by internal differentiation or impact melting. Hadean crust persists into the Archaean and is reworked in subduction zones or thick crustal plateaus above mantle upwellings to form evolved magmas that crystallise zircon with negative εHf(t). These two tectonic settings also facilitate adiabatic or flux melting of convecting mantle to form juvenile mafic magmas, which are reworked to produce evolved magmas that crystallise zircon with approximately chondritic εHf(t). Juvenile melt extraction produces a complementary melt-depleted, rigid, and buoyant lithospheric mantle, which stabilises the evolved crustal nuclei of Earth’s first cratons. The zircon εHf(t)–time plots show the corresponding zircon-Hf isotope characteristics of evolved crust from the Yilgarn craton between the Hadean and Archaean eons.

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