Unmelted cosmic metal particles in the Indian Ocean

Shyam Prasad, M., Rudraswami, N. G., De Araujo, A. A. and Khedekar, V. D.

Meteoritics & Planetary Science. doi: 10.1111/maps.12858


“Fe-Ni metal is a common constituent of most meteorites and is an indicator of the thermal history of the respective meteorites, it is a diagnostic tool to distinguish between groups/subgroups of meteorites. In spite of over a million micrometeorites collected from various domains, reports of pure metallic particles among micrometeorites have been extremely rare. We report here the finding of a variety of cosmic metal particles such as kamacite, plessite, taenite, and Fe-Ni beads from deep-sea sediments of the Indian Ocean, a majority of which have entered the Earth unaffected by frictional heating during atmospheric entry. Such particles are known as components of meteorites but have never been found as individual entities. Their compositions suggest precursors from a variety of meteorite groups, thus providing an insight into the metal fluxes on the Earth. Some particles have undergone heating and oxidation to different levels during entry developing features similar to I-type cosmic spherules, suggesting atmospheric processing of individual kamacites/taenite grains as another hitherto unknown source for the I-type spherules. The particles have undergone postdepositional aqueous alteration transforming finally into the serpentine mineral cronstedtite. Aqueous alteration products of kamacite reflect the local microenvironment, therefore they have the potential to provide information on the composition of water in the solar nebula, on the parent bodies or on surfaces of planetary bodies. Our observations suggest it would take sustained burial in water for tens of thousands of years under cold conditions for kamacites to alter to cronstedtite.”


Comment on “Unmelted cosmic metal particles in the Indian Ocean” by Prasad et al..
Genge, M. J. and Van Ginneken, M.

Meteorit Planet Sci. doi:10.1111/maps.13013
First published: 1 December 2017

Reply to the comment by M. Genge and M. Van Ginneken on paper entitled “Unmelted cosmic metal particles from the Indian Ocean”

Mokkapati Shyam Prasad, N. G. Rudraswami, Agnelo Alexandre de Araujo and Vijay D. Khedekar

Version of Record online: 1 DEC 2017 | DOI: 10.1111/maps.13010