Phanerozoic emergence of global continental collision and onset of massive crustal eclogitization

Abstract

Abstract Post-Archean secular changes in continental crust composition, which provide key evidence for the evolution of plate tectonics, remain uncertain, particularly regarding the lower crust. Here, by digitizing 18,000 km of seismic profiles, we demonstrate a change in bulk crustal composition at the Proterozoic–Phanerozoic transition. We document that a mafic crustal layer is preserved in Proterozoic orogens but generally absent in Phanerozoic orogens. We explain this fundamental shift by a change in the global subduction style, where continental collision became important in the Phanerozoic. Densification of the lower crust by widespread eclogitization, triggered by continental collision and subduction, led to massive recycling of mafic lower crust into the mantle, leaving behind buoyant felsic crust and promoting the rise of continents, which led to the emergence of large continental areas above sea level and the related Neoproterozoic oxidation event, followed by the explosion of life in the Phanerozoic.