Fig. 3: Titanium isotopic effects from Ti³⁺ as recorded by ureilites and diogenites.

The δ⁴⁹Ti data of the ~3.8 Ga Isua metabasalts are from ref. ²⁶. Modeling results for melt extraction from a chondritic precursor with the presence of Ti³⁺ are shown for comparison, where the red solid and red dashed curves represent partial melts and melting residues, respectively, after melt extraction at f_Ti = 0.2 (see Method for the modeling details). The shaded red, blue, and orange boxes cover the ranges of δ⁴⁹Ti and fO₂ for ureilites, diogenites, and Earth’s upper mantle in the early Archean, respectively. Error bars represent the 2se uncertainties.