Abstract

Polymineral aggregates of rounded shapes (“nodules”) composed of native and sulfide minerals of Cu, Ni, Fe, Ag, and other elements from vein magnetite–calcite–chrysotile rocks with jewelry demantoid in the Korkodinskoe hypermafic massif are described. A common feature of the six identified types of native sulfide nodules, composed of native copper, heazlewoodite, pentlandite, cuprite, and other native sulfide minerals, is their spheroidal shape, which makes them similar to individual grains of other gangue minerals (calcite, magnetite, etc.). In heazlewoodite–pentlandite nodules, specific symplectites of mercuric silver and nickel copper in heazlewoodite, as well as awaruite in Co–pentlandite, were found. The matching set of ore minerals in the host serpentinite vein mass (native copper, mercuric silver, heazlewoodite, pentlandite, awaruite) and nodules from the vein material indicates their genetic connection and the conjugation of demantoid mineralization with the evolving processes of serpentinization. It was established that the nodules formed at temperatures below 380°C under reducing conditions at very low sulfur fugacity values (10^–17–10^–27 bar) and oxygen (10^–30 bar at 200°C to 10^–21 bar at 350°C). For heazlewoodite–pentlandite nodules, such conditions persisted throughout the entire time of their formation, while, for other nodules, the reducing conditions of early parageneses were replaced by oxidative conditions in late parageneses, which is recorded by the replacement of native copper with cuprite. It is assumed that the features of the morphology and structure of native sulfide nodules and the presence of symplectite intergrowths of ore minerals in them are associated with specific conditions created during the decompression of the crust-mantle mixture rising to the surface in the fault zone. The source of the metals was a deep, high-temperature fluid interacting with mafic and ultramafic rocks under reducing conditions at a low water-to-rock ratio.

中文翻译：

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Poldnevskoe 翠榴石矿床（中乌拉尔）天然和硫化矿物集合体的矿物学和形成成因条件

摘要

描述了由天然矿物和硫化物矿物组成的圆形多矿物聚集体（“结核”），这些矿物由 Cu、Ni、Fe、Ag 和其他元素组成，这些元素来自 Korkodinskoe 超镁铁质地块中含有珠宝翠榴石的脉状磁铁矿-方解石-温石棉岩石。六种已识别类型的天然硫化物结核由天然铜、黑铁矿、镍黄铁矿、赤铜矿和其他天然硫化物矿物组成，其共同特征是它们的球形形状，这使得它们与其他脉石矿物（方解石、磁铁矿）的单个颗粒相似。 ， ETC。）。在黑黄铁矿-镍黄铁矿结核中，发现了黑黄铁矿中特定的汞银和镍铜辛矿，以及钴镍黄铁矿中的细铝铜矿。宿主蛇纹石矿脉体中的一组矿石矿物（天然铜、汞银、黑黄铁矿、镍黄铁矿、阿瓦鲁石）和来自矿脉物质的结核表明了它们的成因联系以及浓绿榴石矿化与蛇纹石化演化过程的结合。已确定，结核在低于 380°C 的温度、非常低的硫逸度值（10 ^–17 –10 ^–27 bar）和氧气（200°C 时为 10 ^–30 bar，350°C 时为 10 ^–21 bar）的还原条件下形成。 ℃）。对于黑黄铁矿-镍黄铁矿结核，这种条件在其形成的整个过程中持续存在，而对于其他结核，早期共生体的还原条件被晚期共生体的氧化条件所取代，这是通过用赤铜矿取代天然铜来记录的。据推测，天然硫化物结核的形态和结构特征以及其中矿石矿物辛矿共生的存在与断层带中壳幔混合物上升到地表减压过程中产生的特定条件有关。这些金属的来源是一种深层高温流体，在还原条件下以低水岩比与镁铁质和超镁铁质岩石相互作用。