Oxygen Isotope Ratios in the Crust of Iron Meteorites
نویسندگان
چکیده
The separation factor, aM-0= ( 1 8 0 / 1 6 0 ) magnetite/' ( 1 8 0 / 1 6 0 ) atmospheric oxygen, between the magnetite crust of iron meteorites and atmospheric oxygen has been determined to be 0.9946 ± 0.0005. It is concluded that this fractionation of the oxygen isotopes is the consequence of an equilibrium isotope effect at high temperatures. It can be assumed that this is also valid for cosmic spherules, which are mainly ablation products of iron meteorites. As these spherules are found in sediments of different geological ages, their oxygen isotope ratio can give information on the development of atmospheric oxygen. The difference of the oxygen isotope ratios between magnetite from the lithosphere and airborne magnetite can be used to distinguish between terrestrial and extraterrestrial material.
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