Fig. 3. Initial ²⁰⁶Pb/²⁰⁴Pb ratios versus crystallization ages of the lunar basalts and meteorites.

The lines represent the two-stage Pb isotope evolution of lunar mantle sources at given μ values⁶. The gradient areas are associated with KREEP-poor (yellow) to KREEP-rich (blue) mantle sources according to μ values. The Apollo and meteorite data are from refs. ^6,7,10. Error bars are 2σ s.e. A11, Apollo 11 high-Ti basalts; A12, Apollo 12 low-Ti basalts; A15, Apollo low-Ti basalts; A17, Apollo 17 high-Ti basalts; High-Al, Apollo 14 high-Al basalts; KREEP, Apollo 15 KREEP basalts; Lunar basalt meteorite, low-Ti and very-low-Ti basaltic meteorites (NWA 4734 and NWA 773 clan).

Source data