Hydration bands near 3 μm and weathering of some Antarctic meteorites

Abstract

We studied the degree of weathering of some Antartctic meteorites using the integrated intensity of absorption bands (hydration bands) near 3 μm due to the presence of hydrous minerals. The Allan Hills meteorites measured show stronger integrated intensities than the Yamato meteorites measured, although the number of meteorites we measured is small. This suggests that the Allan Hills meteorites are more weathered than the Yamato meteorites. The Allan Hills meteorites show greater terrestrial ages than other Antarctic meteorites on the basis of cosmic-ray-produced nuclide data. Our results are consistent with the terrestrial age data, because weathering produces hydrous minerals. Integrated intensities near 3 μm vary widely among the Antarctic meteorites reported to be relatively little weathered under microscopic observation. The integrated intensity of hydration bands near 3 μm may have the potential for quantifying the degree of weathering. These quantified data may help in selecting less weathered meteorites from among the Antarctic meteorite collection and may be combined with terrestrial age data to study terrestrial histories of Antarctic meteorites.