Abstract This work presents a detailed study of platinum-group mineral (PGM) assemblages from the Malaya Kamenushka River placer, whose formation is associated with the weathering of the Kamenushensky Uralian–Alaskan type massif, Middle Urals, Russian Federation. The deposit is characterised by the dominance of isoferroplatinum, together with significant numbers of inclusions of Os–Ir–Ru alloys and platinum-group element (PGE) sulfides. A study of the Os–Ir–Ru alloys permitted recognition of two types of iridium with different morphology and composition. The similarity of the PGM assemblages from the Malaya Kamenushka River placer and the lode mineralisation of the Kamenushensky massif is demonstrated. A comparison of PGM assemblages from the Malaya Kamenushka River placer with other placers and massifs of the Ural platinum belt demonstrates significant differences in the number of Os–Ir–Ru inclusions. Such differences for minerals of refractory elements cannot be explained by the vertical zoning of the lode mineralisation. Most probably this is associated with the enrichment of the primary substrate with Os, Ir and Ru and/or the degree of melting, depending on the chosen model of formation of the Uralian–Alaskan type massifs.

中文翻译：

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来自俄罗斯中乌拉尔的马来亚 Kamenushka 河砂矿的铂族矿物

摘要 这项工作详细研究了来自马来亚 Kamenushka 河砂矿的铂族矿物 (PGM) 组合，其形成与俄罗斯联邦中乌拉尔 Kamenushensky Uralian-Alaskan 型地块的风化有关。该矿床的特点是异铁铂占主导地位，以及大量 Os-Ir-Ru 合金和铂族元素 (PGE) 硫化物的夹杂物。对 Os-Ir-Ru 合金的研究允许识别具有不同形态和成分的两种类型的铱。证明了来自马来亚 Kamenushka 河砂矿的 PGM 组合与 Kamenushensky 地块的矿脉矿化的相似性。来自马来亚 Kamenushka 河砂矿的 PGM 组合与乌拉尔铂金带的其他砂矿和地块的比较表明 Os-Ir-Ru 包裹体的数量存在显着差异。难熔元素矿物的这种差异不能用矿脉矿化的垂直分区来解释。这很可能与 Os、Ir 和 Ru 的主要底物的富集和/或熔化程度有关，这取决于所选的乌拉尔-阿拉斯加类型地块的形成模型。