Late delivery of exotic chromium to the crust of Mars by water-rich carbonaceous asteroids.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36383650.
- Also identified by DOI 10.1126/sciadv.abp8415 and PMC identifier 9668285.
- Licence recorded as CC BY-NC.
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Abstract
The terrestrial planets endured a phase of bombardment following their accretion, but the nature of this late accreted material is debated, preventing a full understanding of the origin of inner solar system volatiles. We report the discovery of nucleosynthetic chromium isotope variability (μ<sup>54</sup>Cr) in Martian meteorites that represent mantle-derived magmas intruded in the Martian crust. The μ<sup>54</sup>Cr variability, ranging from -33.1 ± 5.4 to +6.8 ± 1.5 parts per million, correlates with magma chemistry such that samples having assimilated crustal material define a positive μ<sup>54</sup>Cr endmember. This compositional endmember represents the primordial crust modified by impacting outer solar system bodies of carbonaceous composition. Late delivery of this volatile-rich material to Mars provided an exotic water inventory corresponding to a global water layer >300 meters deep, in addition to the primordial water reservoir from mantle outgassing. This carbonaceous material may also have delivered a source of biologically relevant molecules to early Mars.