Collisional mixing between inner and outer solar system planetesimals inferred from the Nedagolla iron meteorite

TL;DR

This study presents isotopic evidence from the Nedagolla meteorite indicating that collisional mixing between inner and outer solar system planetesimals occurred late in solar system history, likely due to early planetary collisions.

Contribution

It provides the first isotopic evidence of collisional mixing between non-carbonaceous and carbonaceous bodies in the early solar system.

Findings

Nedagolla has intermediate isotopic compositions between NC and CC meteorites.

The meteorite's formation involved collisional mixing of differentiated bodies.

Evidence suggests mixing occurred during a hit-and-run collision, influencing volatile depletion.

Abstract

The ungrouped iron meteorite Nedagolla is the first meteorite with bulk Mo, Ru, and Ni isotopic compositions that are intermediate between those of the non-carbonaceous (NC) and carbonaceous (CC) meteorite reservoirs. The Hf-W chronology of Nedagolla indicates that this mixed NC-CC isotopic composition was established relatively late, more than 7 million years after Solar System formation. The mixed NC-CC isotopic composition is consistent with the chemical composition of Nedagolla, which combines signatures of metal segregation under more oxidizing conditions (relative depletions in Mo and W), characteristic for CC bodies, and more reducing conditions (high Si and Cr contents), characteristic for some NC bodies, in a single sample. These data combined suggest that Nedagolla formed as the result of collisional mixing of NC and CC core material, which partially re-equilibrated with silicate mantle material that predominantly derives from the NC body. These mixing processes might have occurred during a hit-and-run collision between two differentiated bodies, which also provides a possible pathway for Nedagolla's extreme volatile element depletion. As such, Nedagolla provides the first isotopic evidence for early collisional mixing of NC and CC bodies that is expected as a result of Jupiter's growth.