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Plate tectonics is among the most important geological processes on Earth, but its emergence and evolution remain unclear. Here we extrapolate models of present-day plate tectonics to the past and propose that since about three billion years ago the rise of continents and the accumulation of sediments at continental edges and in trenches has provided lubrication for the stabilization of subduction and has been crucial in the development of plate tectonics on Earth. We conclude that the two largest surface erosion and subduction lubrication events occurred after the Palaeoproterozoic Huronian global glaciations (2.45 to 2.2 billion years ago), leading to the formation of the Columbia supercontinent, and after the Neoproterozoic 'snowball' Earth glaciations (0.75 to 0.63 billion years ago). The snowball Earth event followed the 'boring billion'-a period of reduced plate tectonic activity about 1.75 to 0.75 billion years ago that was probably caused by a shortfall of sediments in trenches-and it kick-started the modern episode of active plate tectonics.

High-resolution three-dimensional thermomechanical simulations of Earth's lithosphere indicate that mantle plumes could have initiated the first subduction zones, but only in the hotter early Earth for old oceanic plates. Taras Gerya and co-authors use high-resolution three-dimensional numerical thermomechanical models to show that mantle plumes could have initiated the first subduction zones. They find that several factors combine to trigger self-sustained subduction: a strong, negatively buoyant oceanic lithosphere, focused magmatic weakening and thinning of lithosphere above the plume, and lubrication of the slab interface by hydrated crust. They also conclude that plume-induced subduction was only feasible in the hotter early Earth for old oceanic plates, as younger plates would have favoured episodic lithospheric drips rather than self-sustained subduction and global plate tectonics. Scientific theories of how subduction and plate tectonics began on Earth—and what the tectonic structure of Earth was before this—remain enigmatic and contentious1. Understanding viable scenarios for the onset of subduction and plate tectonics2,3 is hampered by the fact that subduction initiation processes must have been markedly different before the onset of global plate tectonics because most present-day subduction initiation mechanisms require acting plate forces and existing zones of lithospheric weakness, which are both consequences of plate tectonics4. However, plume-induced subduction initiation5,6,7,8,9 could have started the first subduction zone without the help of plate tectonics. Here, we test this mechanism using high-resolution three-dimensional numerical thermomechanical modelling. We demonstrate that three key physical factors combine to trigger self-sustained subduction: (1) a strong, negatively buoyant oceanic lithosphere; (2) focused magmatic weakening and thinning of lithosphere above the plume; and (3) lubrication of the slab interface by hydrated crust. We also show that plume-induced subduction could only have been feasible in the hotter early Earth for old oceanic plates. In contrast, younger plates favoured episodic lithospheric drips rather than self-sustained subduction and global plate tectonics.

More than 50 per cent of the Earth´s upper mantle consists of olivine and it is generally thought that mantle-derived melts are generated in equilibrium with this mineral. Here, however, we show that the unusually high nickel and silicon contents of most parental Hawaiian magmas are inconsistent with a deep olivine-bearing source, because this mineral together with pyroxene buffers both nickel and silicon at lower levels. This can be resolved if the olivine of the mantle peridotite is consumend by reaction with melts derived from rexycled oceanic crust, to form a secondary pyroxenitic source. Our modelling shows that more than half of Hawaiian magmas formed during the past 1 Myr came from this source. In addition, we estimate that the proportion of recycled (oceanic) crust varies from 30 per cent near the plume centre to insignificant levels at the plume edge. These results are also consistent with volcano volumes, magma volume flux and seismological observations.