Terrestrial alteration of Fe-Ni metals in Antarctic ordinary chondrites and the relationship to their terrestrial ages
Terrestrial alteration of Fe-Ni metals to limonites in ordinary chondrites is faster for kamacite than for taenite. H chondrites which have high ratios of kamacite/taenite alter more easily than LL chondrites which have the low ratios, L chondrites being intermediate. Qualitative weathering indices,...
| Main Authors: | , |
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| Format: | Report |
| Language: | English |
| Published: |
Department of Earth Sciences, Faculty of Science, Ibaraki University
1991
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| Online Access: | https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=4550 http://id.nii.ac.jp/1291/00004550/ https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=4550&item_no=1&attribute_id=18&file_no=1 |
| Summary: | Terrestrial alteration of Fe-Ni metals to limonites in ordinary chondrites is faster for kamacite than for taenite. H chondrites which have high ratios of kamacite/taenite alter more easily than LL chondrites which have the low ratios, L chondrites being intermediate. Qualitative weathering indices, A, B, and C, correspond to measured average alteration degrees (proportion of metal converted to limonite) of <5%, 10-20%, and >50%, respectively. The surfaces of chondritic meteorites show higher degrees in alteration of Fe-Ni metals than the interiors, although the difference in the degree is merely a factor of two. There is no correlation between the average alteration degrees and the terrestrial ages for H and L chondrites, but the average alteration degree seem to depend upon the degrees of impact shocks which the chondrites had suffered in or on the parent body. |
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