  Earth's surface is deficient in available forms of many elements considered
limiting for prebiotic chemistry. In contrast, many extraterrestrial rocky
objects are rich in these same elements. Limiting prebiotic ingredients may,
therefore, have been delivered by exogenous material; however, the mechanisms
by which exogeneous material may be reliably and non-destructively supplied to
a planetary surface remains unclear. Today, the flux of extraterrestrial matter
to Earth is dominated by fine-grained cosmic dust. Although this material is
rarely discussed in a prebiotic context due to its delivery over a large
surface area, concentrated cosmic dust deposits are known to form on Earth
today due to the action of sedimentary processes. Here we combine empirical
constraints on dust sedimentation with dynamical simulations of dust formation
and planetary accretion to show that localized sedimentary deposits of cosmic
dust could have accumulated in arid environments on early Earth, in particular
glacial settings that today produce cryoconite sediments. Our results challenge
the widely held assumption that cosmic dust is incapable of fertilizing
prebiotic chemistry. Cosmic dust deposits may have plausibly formed on early
Earth and acted to fertilize prebiotic chemistry.
