Extended Data Fig. 3: A mixing curve showing the correlated change of K concentration and ε40K values with various degrees of crustal K addition.
From: Potassium-40 isotopic evidence for an extant pre-giant-impact component of Earth’s mantle
The labeled percentage indicates the addition amount of crustal materials in the mixture. The blue dashed lines mark the resolvability of 40K anomaly (ε40K = ± 0.3) and the shaded area indicates no resolvable 40K anomaly. The ε40K values of OIB and crustal materials used for the mixing curve are -0.6 ± 0.1 and 0, respectively. The K2O concentrations of OIB and crustal materials are assumed to be 0.35% and 2%, respectively. The mixing curve shows that an OIB sample contaminated with >15% crustal materials would result in ε40K values unresolvable from the modern mantle.
