Annama H chondrite—Mineralogy, physical properties, cosmic ray exposure, and parent body history

1,2,3Tomáš Kohout et al (>10)*
Meteoritics & Planetary Science (in Press) Link to Article [DOI: 10.1111/maps.12871]
1Department of Physics, University of Helsinki, Finland
2Institute of Geology, The Czech Academy of Sciences, Praha, Czech Republic
3Finnish Fireball Network, Finland
*Find the extensive, full author and affiliation list on the publishers website
Published by arrangement with John Wiley & Sons

The fall of the Annama meteorite occurred early morning (local time) on April 19, 2014 on the Kola Peninsula (Russia). Based on mineralogy and physical properties, Annama is a typical H chondrite. It has a high Ar-Ar age of 4.4 Ga. Its cosmic ray exposure history is atypical as it is not part of the large group of H chondrites with a prominent 7–8 Ma peak in the exposure age histograms. Instead, its exposure age is within uncertainty of a smaller peak at 30 ± 4 Ma. The results from short-lived radionuclides are compatible with an atmospheric pre-entry radius of 30–40 cm. However, based on noble gas and cosmogenic radionuclide data, Annama must have been part of a larger body (radius >65 cm) for a large part of its cosmic ray exposure history. The 10Be concentration indicates a recent (3–5 Ma) breakup which may be responsible for the Annama parent body size reduction to 30–35 cm pre-entry radius.

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