The evolution of the Kapoeta howardite based on fossil track studies

Abstract

A detailed study has been made of the occurrence of high particle track densities in the gas-rich howardite, Kapoeta. In addition to the high track density pyroxene grains previously reported, feldspar grains were found with track densities and track density gradients identical with those in the pyroxenes. The spatial distribution of track-rich grains in the dark gas-rich portion of the meteorite is random. Grains that are track-rich are not a chemically distinct group; they show the same range of compositions as grains with normal track densities. The low energy cosmic radiation that produced the high track densities and the enrichment in rare gases occurred during the extensive brecciation and mixing of Kapoeta parent materials.