| Abstract: | Abstract The radioactivities Be10, Al26, Cl36, Mn53, Ni59, and Co60 and the rare gas isotopes were measured in a sample taken from the surface of the Hoba meteorite. The spallation-produced radioactivities indicate that the sample was at a depth of 35 to 40 cm when the body was in space. The Ni59 activity indicates that the terrestrial age of Hoba is less than 80,000 years. Its Cl36-Ar36 exposure age is 263±40 million years. The Cl36 and rare-gas isotopes were also measured in the Deelfontein meteorite; its Cl36-Ar36 exposure age is 400±40 million years. The Cl36 and the Ni59 were also measured in a sample of Sikhote-Alin. In both Hoba and Sikhote-Alin the Ni59, which is a neutron-produced isotope, is higher than would be expected from the Cl36 content. This indicates that solar flares contributed to the neutron-produced isotopes in these iron meteorites. |
