Native osmium from the Guli Massif, Northern Siberia, Russia
Native osmium from the Guli Massif, Northern Siberia, Russia
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来自俄罗斯西伯利亚北部古里地块的原生锇
DOI：
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发表时间：
2011
影响因子：
1.8
通讯作者：
I. Badanina
中科院分区：
文献类型：
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作者：
R. Merkle;K. Malitch;P. Gräser;I. Badanina
摘要 对麦梅查-科图伊省古利地块内两个不同砂矿（即 Ingaringda 和 Burlakovsky）的天然锇进行了矿物成分评估，显示出不同地点之间的系统差异。天然锇颗粒显示出铱向边缘增加，并且由聚集体组成的金块定义了铱优先替代锇的趋势。可以证明所研究的两个放置者之间的 Os/Ir 比率存在统计学上可靠的差异。从结构和成分特征可以得出结论，布尔拉科夫斯基砂矿的天然锇形成温度高于地壳条件下的合理假设温度。两个砂矿之间的 Os/Ir 比率差异可归因于地幔源中天然锇的分步结晶（在不同事件中被开采形成古里地块），或归因于硅酸盐熔体侵入后在地壳条件下结晶过程中 Os/Ir 值的降低。
SummaryNative osmium from two different placer occurrences (i.e., Ingaringda and Burlakovsky) within the Guli Massif, Maimecha-Kotui Province, was evaluated for mineral compositions that show systematic differences between the localities. Grains of native osmium show increases in iridium towards the rim, and nuggets consisting of aggregates define trends of preferential substitution of osmium by iridium. A statistically reliable difference in Os/Ir ratios between the two studied placers can be demonstrated. From textural and compositional characteristics it is concluded that the native osmium of the Burlakovsky placer formed at temperatures higher than can be assumed to be reasonable for crustal conditions. The difference in the Os/Ir ratios between the two placers can be attributed to fractional crystallization of native osmium either in the mantle source, which was tapped in different events to form the Guli Massif, or to decreasing Os/Ir values during crystallization under crustal conditions after intrusion of the silicate melt(s).