Pallasite Seymchan contains three morphological types of olivine grains, which occur in a FeNi matrix and have rounded, angular, and fragmental shape. Sometimes the rounded grains form clusters. The texture and mineralogical features of the olivine cluster in pallasite Seymchan were studied by optical microscopy, EMPA, and SEM. The data obtained indicate an imposed impact event in the Seymchan history, which led to local melting and rounding of initially angular olivine grains, as well as to melting of adjacent regions of the host FeNi metal. Local impact melting reasonably explains the observed textures and the coexistence of three morphological types of olivine in the pallasite Seymchan. Configuration of the intergranular boundaries in the olivine cluster indicates the phenomenon of coalescence. The phosphate–metal–sulfide films decorating the intergranular boundaries in the cluster represent the binding medium necessary for the coalescence of the olivine melt drops in the FeNi melt. The texture of the films demonstrates a liquid immiscibility in phosphate–metal–troilite melt. The metal–troilite assemblage in the films differs in texture and chemical composition from that of ordinary chondrites.

中文翻译：

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Seymchan 陨石局部冲击熔化的证据

Pallasite Seymchan 包含三种形态类型的橄榄石颗粒，它们出现在 FeNi 基质中，具有圆形、角形和碎片形状。有时圆形颗粒形成簇。通过光学显微镜、EMPA 和 SEM 研究了橄榄石 Seymchan 橄榄石簇的结构和矿物学特征。获得的数据表明，Seymchan 历史上发生了强加的撞击事件，导致最初有棱角的橄榄石颗粒局部熔化和变圆，以及主体 FeNi 金属的相邻区域熔化。局部撞击熔化合理地解释了在橄榄石 Seymchan 中观察到的质地和三种形态类型的橄榄石的共存。橄榄石簇中晶间边界的配置表明了聚结现象。装饰簇中晶界的磷酸盐-金属-硫化物薄膜代表了橄榄石熔体液滴在 FeNi 熔体中聚结所必需的结合介质。薄膜的质地表明在磷酸盐-金属-硫钛矿熔体中液体不混溶。薄膜中的金属-硫钛矿组合在质地和化学成分上与普通球粒陨石不同。