Dissipation of the Solar System’s Debris Disk Recorded in Primitive Meteorites

Many newly formed Sun-like stars show evidence of debris disks composed of dust generated through destructive collisions among residual planetesimals. These are inferred to survive at a detectable level over the first ~100 Myr of their parent star’s lifetime. We hypothesize that the most primitive meteorites were processed as a result of impacts as our Solar System’s debris disk dissipated, rather than as a result of heat generated by decay of 26Al. We show how the iodine–xenon (I–Xe) record from chondrules in the Chainpur meteorite supports this hypothesis, and use it to constrain the decline in the impact rate. We demonstrate that it is the creation of I–Xe sites during compaction that is recorded by the chondrule dataset. We show that, to account for the broader I–Xe record from primitive material, a consistent picture requires that the dissipation of our Solar System’s debris disk had a timescale of around 40–50 Myr in this period. Against this backdrop, the late addition of siderophiles to the Earth in a single large impact may represent a rare phenomenon in planetary system formation that has been anthropically selected.