Johnson et al. 2022. Giant impacts and the origin and evolution of continents.

Using the oxygen isotope compositions of dated magmatic zircon, we show that the Pilbara Craton in Western Australia, Earth’s best-preserved Archaean (4.0–2.5 billion years ago; Ga) continental remnant, was built in three stages. Stage 1 zircons (3.6–3.4 Ga) form two age clusters with one-third recording sub-mantle δ18O, indicating crystallization from evolved magmas derived from hydrothermally-altered basaltic crust like that in modern-day Iceland. Stage 2 (3.4–3.0 Ga) zircons mostly have mantle-like δ18O and crystallized from parental magmas formed near the base of the evolving continental nucleus. Stage 3 (<3.0 Ga) zircons have above-mantle δ18O, indicating efficient recycling of supracrustal rocks.