Abstract
The size, density, and chemical characteristics of solar system bodies have been shaped by material transport during the protoplanetary disk stage. This includes transport from the inner to outer solar system of refractory dust grains that carry nucleosynthetic anomalies. Here, we show that rare earth element (REE) isotopes in fine-grained calcium-aluminum-rich inclusions (CAIs) display anomalies stemming from incomplete mixing of r-, s-, and p-process nucleosynthesis. The data points define two correlations, which are best explained by mixing between three isotopic reservoirs in two successive stages, one of which involved a variable admixture of a p-process component. We propose that CAI precursors formed in the inner solar system and were subsequently transported by FU Orionis outbursts from the disk to the envelope where they mixed with an isotopically distinct reservoir before settling on the midplane.