The Behavior of Fe—Ni Metal during Thermal Metamorphism of the Jilin Chondrite |
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摘 要: |
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关 键 词: | 铁 镍 球粒状陨石 热变质作用 扫描电子显微镜 |
The behavior of Fe-Ni metal during thermal metamorphism of the Jilin Chondrite |
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Authors: | Xiande Xie Daode Wang |
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Institution: | (1) Institute of Geochemistry, Academia Sinica, 510640 Guangzhou |
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Abstract: | Conclusions 1. Under heat influence, the mobility of Fe-Ni metal was relatively high as compared with silicates. During thermal metamorphism
of the Jilin meteorite (T ⩽ 800 °C), fine Fe-Ni metal particles in silicate condrules and matrix aggregated into coarse metal grains, which are as
large as 5–10 mm in size,in situ or after a short-distance migration and concentration, and some even aggregated into metal nodules as large as 20–30mm in
size, but their chemical composition still remains unchanged.
2. High-temperature and high pressure, as well as shock-loading experiments on Jilin meteorite samples provide further evidence
that temperature plays an important role in metal /silicate redistribution and differentiation. The variation of temperature
exerts great influence on the mode of metal-silicate redistribution. At about 1000 °C or less, metal particles moved and aggregated
into rather coarse grains by thermal diffusion, or through the formation of eutectic melts together with FeS. When the temperature
reaches about 1300 °C, full melting take place in the meteorite specimens, and at this time metals and metal sulfides play
an important role in the immiscibility and gravitational differentiation of metal-silicate melts, thus leading to the rapid
separation of metals or metal-sulfides from silicates, followed by the sinking of pure metals and metal-sulfides to the bottom
of the experimental products and the formation of silicate melts almostly with no metals and sulfides in the upper parts. |
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