  The fundamentally different isotopic compositions of non-carbonaceous (NC)
and carbonaceous (CC) meteorites reveal the presence of two distinct reservoirs
in the solar protoplanetary disk that were likely separated by Jupiter.
However, the extent of material exchange between these reservoirs, and how this
affected the composition of the inner disk are not known. Here we show that NC
meteorites display broadly correlated isotopic variations for Mo, Ti, Cr, and
Ni, indicating the addition of isotopically distinct material to the inner
disk. The added material resembles bulk CC meteorites and Ca-Al-rich inclusions
in terms of its enrichment in neutron-rich isotopes, but unlike the latter
materials is also enriched in s-process nuclides. The comparison of the
isotopic composition of NC meteorites with the accretion ages of their parent
bodies reveals that the isotopic variations within the inner disk do not
reflect a continuous compositional change through the addition of CC dust,
indicating an efficient separation of the NC and CC reservoirs and limited
exchange of material between the inner and outer disk. Instead, the isotopic
variations among NC meteorites more likely record a rapidly changing
composition of the disk during infall from the Sun's parental molecular cloud,
where each planetesimal locks the instant composition of the disk when it
forms. A corollary of this model is that late-formed planetesimals in the inner
disk predominantly accreted from secondary dust that was produced by collisions
among pre-existing NC planetesimals.
