Light O isotopes trace subduction
Olivine grains preserved in 3.3 Ga komatiites carry oxygen isotope signatures of the primitive mantle, recording subduction of oceanic crust at that time.
Ouyang, Dongjian · Huiming, Bao · Byerly, Gary R. · Li, Qiuli
Communications Earth and Environment 2024
δ¹⁸O = 3.6–4.7‰ (Group II)
Fo = 91–93 (Group II)
δ¹⁸O = 4.9–5.4‰ (Group I)
Fo = 93–95 (Group I)