Although Cu-sulfide mineralization within the Loolekop pipe of the Phalaborwa Igneous Complex has been extensively studied, certain aspects of the sulfide metallogenesis remain unclear. This research aims to constrain the relative timing and processes involved in Cu-sulfide mineralization within the Loolekop pipe through textural analysis and trace element composition of the three different types of sulfide assemblages in this intrusion. The first primary magmatic mineralization phase contains dispersed bornite with chalcopyrite exsolution and local traces of chalcocite and covellite related to fluid alteration, whereas the second primary phase is characterized by veins of chalcopyrite with cubanite exsolution. The third mineralization phase relates to leaching of primary sulfide assemblages by oxidizing fluids, resulting in desulfurization and the formation of valleriite [(Fe 2+ ,Cu) 4 (Mg,Al) 3 S 4 (OH,O) 6 ] and magnetite. Whole-rock ICP-MS analyses of platinum-group elements (PGE) indicate a mantle origin of the primary Cu-sulfides (bornite-chalcopyrite assemblages). In situ trace element analyses of sulfide assemblages also show evidence of external material input, most likely of crustal origin, during magma and sulfide liquid ascent, before decoupling of the sulfide liquid and the melt, although the exact source is unclear. The enrichment of Pd-group PGE (PPGE: Pd, Pt) over Ir-group PGE (IPGE: Os, Ir, Ru) in Cu-sulfide phases suggests the presence of an intermediate solid solution (iss)-monosulfide solid solution (mss) system. It is proposed that a Cu- and PPGE-enriched sulfide liquid fractionated from an IPGE-enriched mss, followed by the formation of an iss, and finally the extraction of a PPGE-rich Cu-liquid from the iss forming the bornite-chalcopyrite assemblages. Sulfide textures and the presence of chalcopyrite veins suggest that the iss was leached by high-temperature hydrothermal fluids at depth that remobilized and precipitated Cu along the fractures within the intrusion. Subsequently, all the primary magmatic phases were affected by late-stage fluids, which triggered their alteration into valleriite, also precipitating along fractures within the Loolekop pipe.

中文翻译：

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来自 Phalaborwa Loolekop 管道的 Cu 硫化物中的铂族和微量元素：对成矿过程的影响

尽管 Phalaborwa 火成岩复合体 Loolekop 管道内的铜硫化物矿化已被广泛研究，但硫化物成矿作用的某些方面仍不清楚。本研究旨在通过结构分析和该侵入体中三种不同类型硫化物组合的微量元素组成来限制 Loolekop 管道内铜硫化物矿化所涉及的相对时间和过程。第一个原生岩浆成矿相包含分散的斑铜矿和黄铜矿出溶，以及与流体蚀变有关的局部辉铜矿和铜铜矿痕迹，而第二个原生矿化相的特征是黄铜矿脉和立方石英出溶。第三矿化阶段涉及通过氧化流体浸出原生硫化物组合，导致脱硫并形成钒铅矿[(Fe 2+ ,Cu) 4 (Mg,Al) 3 S 4 (OH,O) 6 ]和磁铁矿。铂族元素 (PGE) 的全岩 ICP-MS 分析表明原生铜硫化物（斑铜矿-黄铜矿组合）的地幔起源。硫化物组合的原位微量元素分析也显示了外部物质输入的证据，最有可能是地壳起源，在岩浆和硫化物液体上升期间，在硫化物液体和熔体解耦之前，尽管确切来源尚不清楚。在 Cu-硫化物相中 Pd-组 PGE（PPGE：Pd、Pt）比 Ir-组 PGE（IPGE：Os、Ir、Ru）富集表明存在中间固溶体 (iss)-单硫化物固溶体 (mss) ） 系统。建议从富含 IPGE 的 mss 中分馏出富含 Cu 和 PPGE 的硫化物液体，随后形成国际空间站，最后从国际空间站中提取富含 PPGE 的 Cu 液体，形成斑铜矿-黄铜矿组合。硫化物质地和黄铜矿脉的存在表明，该国际空间站被深部的高温热液浸出，沿着侵入体内的裂缝重新移动并沉淀出铜。随后，所有的原生岩浆相都受到晚期流体的影响，引发了它们转变为钒铅矿，并沿 Loolekop 管内的裂缝沉淀。硫化物质地和黄铜矿脉的存在表明，该国际空间站被深部的高温热液浸出，沿着侵入体内的裂缝重新移动并沉淀出铜。随后，所有的原生岩浆相都受到晚期流体的影响，引发了它们转变为钒铅矿，并沿 Loolekop 管内的裂缝沉淀。硫化物质地和黄铜矿脉的存在表明，该国际空间站被深部的高温热液浸出，沿着侵入体内的裂缝重新移动并沉淀出铜。随后，所有的原生岩浆相都受到晚期流体的影响，引发了它们转变为钒铅矿，并沿 Loolekop 管内的裂缝沉淀。