State of Fe atoms in minerals of the Saratov chondrite affected by spherical impact wavesстатья
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Дата последнего поиска статьи во внешних источниках: 20 сентября 2013 г.
Аннотация:The structural and valent state of iron atoms was studied by Mossbauer spectroscopy on Fe-57 nuclei in two intact samples of the Saratov chondrite (L4, fall) affected by spherically convergent detonation waves. In accordance with the geometry of detonation wave loading, an increase in peak pressure was produced from the sphere's surface to its center, where ultrahigh impact loading was reached. The Mossbauer spectra indicate the following iron-bearing phases: olivine, pyroxene, iron sulfides, kamacite, and spinel with magnetically ordered and paramagnetic structures. Phase transformations accompanied by oxidation-reduction processes were observed from the surface to the center of the compressed meteorite samples. The reduction of iron to metallic iron occurs From the zone of plastic deformation to the zone of partial melting, whereas the fraction of Fe2+ ions increases from the zone of partial melting to the zone of melting. The amount of impurities and local inhomogeneities of iron atoms in iron-bearing minerals increase with an increasing degree of impact metamorphism. In comparison to the monolithic sample, the sample prepared from the matrix material showed displacement of the impact zones toward the sample surface, a change in thickness, and an increase in the degree of local distortions in mineral structures in each zone.