Fig. 7: Compositional mantle layering predicted by a global-scale mantle-convection model after 4.57 Ga model time from ref. 31.
From: Widespread PREMA in the upper mantle indicated by low-degree basaltic melts
Oceanic crust is shown in black, the depleted mantle from which the crust is extracted is shown in grey, and the unprocessed mantle is in orange. Each boundary from outside to inside represents the surface, lithosphere-asthenosphere boundary, 670 km discontinuity, and core-mantle boundary. The diagram on the right shows the present-day depth distribution of the fraction of unprocessed mantle, while the vertical line represents the average fraction of unprocessed mantle.
