Bradley Peters, Marc Halfar, Courtney Rundhaug, Paterno Castillo, Maria Schönbächler

The unresolved question of when modern tectonic processes arose on Earth has restricted our understanding of how and how quickly Earth reached its present, habitable form. Plate tectonics, and in particular deep subduction, is central to many facets of habitability: it controls heat flow, biogeochemical cycling, and creates a variety of marine and terrestrial biomes that are crucial for biological evolution. Many petrological, geodynamical, and geochemical perspectives have offered circumstantial evidence for both an early onset of plate tectonics, in the first 10% of Earth’s history, or a late onset after the great oxidation event (2.5 Ga ago). We present geochemical evidence from the products of early subduction, which have been recycled into the deep mantle and then tapped by the modern Marquesas volcanic hotspot. These products must have been stored and protected in the deep mantle largely unchanged for more than four billion years before they were brought to the surface by the Marquesas mantle plume. The felsic composition of these subducted materials further requires that both subcrustal melting and sedimentation processes were active in some form before this time. The early development of a mature plate tectonic system on Earth implies that its pathway to complex life was protracted: the foundations for habitability potentially began billions of years before the emergence of life. Emerging planetary bodies may, therefore, need long-term sustained plate tectonic processes to become host to complex biological systems. Further, the preservation of evidence for foundational planetary events in geologically young rocks, rather than ancient rocks, reveals that Earth’s volcanic hotspots could provide a defining perspective on the early planetary-scale processes that build Earth-like planets.