Magmatic Ni-Cu-PGE sulfide mineralisation is mostly confined to tholeiitic to komatiitic mafic-ultramafic intrusions, yet there have been an increasing number of occurrences recorded in alkaline-ultramafic, post-collisional magmatic systems, particularly in the lower and middle crust that generally display a characteristic Cu-Au-Te enrichment over more conventional Ni-Cu(-PGE) mineralisation. The Mordor Alkaline Igneous Complex, Australia, is a mid-crustal, zoned alkaline complex comprised of a syenite body with an alkaline mafic-ultramafic subcomplex containing dunites, wehrlites and shonkinites. Sulfide mineralisation is present either in thin, PGE-enriched stratiform ‘reefs’ within layered ultramafics in the centre of the subcomplex, or in thicker zones of Cu(-Au-PGE-Te) sulfide hosted by phlogopite-rich shonkinites towards the intrusion margins. This latter style comprises blebs of pyrite, chalcopyrite and minor millerite and PGE tellurides formed from the cooling of a Cu-dominant sulfide liquid. Primary igneous calcite is present in intimate association with the sulfide. We note that the circular nature of the complex, with a dunite core and shonkinite rim with chalcophile element mineralisation, is comparable to the pipe-like, intracratonic, alkaline-ultramafic Aldan Shield intrusions in Russia. As such, Mordor may have an intracratonic rather than post-collisional affinity. Nevertheless, sulfide mineralisation is typical of other alkaline-hosted occurrences, with a Cu-Au-Te-rich signature, low Ni contents and textural association with calcite, supporting models of chalcophile metal and S fluxing alongside carbonate in alkaline systems derived from low degrees of partial melting of hydrous and carbonated mantle sources. Mordor illustrates that alkaline igneous rocks are prospective for magmatic Cu-Au-PGE-Ni sulfide mineralisation, and the classic ‘marginal base metal– and sulfide-rich’ and ‘stratiform PGE-rich and sulfide-poor’ mineralisation styles may both be found in such intrusions.

中文翻译：

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岩浆Cu-Au-Te(-Ni-PGE)硫化物气泡在澳大利亚北领地莫多复合体碱性基性岩中的侵位

岩浆 Ni-Cu-PGE 硫化物矿化主要局限于拉斑岩到科马提质基性-超镁铁质侵入体，但在碱性-超镁铁质、碰撞后岩浆系统中记录的矿床数量越来越多，特别是在下地壳和中地壳中，通常在更传统的 Ni-Cu(-PGE) 矿化中显示出特征性的 Cu-Au-Te 富集。澳大利亚的莫多碱性火成岩复合体是一个中地壳、分区的碱性复合体，由正长岩体和碱性镁铁质-超镁铁质亚复合体组成，该亚复合体包含纯长岩、方长岩和方闪长岩。硫化物矿化存在于亚复合体中心的层状超基性岩内的薄的、富含 PGE 的层状“礁”中，或在由富含金云母的闪金矿向侵入边缘承载的较厚的 Cu(-Au-PGE-Te) 硫化物区域中。后一种类型包括黄铁矿、黄铜矿和次要的堇青石和 PGE 碲化物的气泡，这些气泡是由 Cu 占主导地位的硫化物液体冷却形成的。原生火成岩方解石与硫化物密切相关。我们注意到该复合体的圆形性质，具有单质岩核心和具有亲硫元素矿化的菱镁矿边缘，可与俄罗斯的管状、克拉通内、碱性超镁铁质阿尔丹地盾侵入体相媲美。因此，魔多可能具有内在而不是碰撞后的亲和力。然而，硫化物矿化是其他碱性矿床的典型特征，具有富含 Cu-Au-Te 的特征、低 Ni 含量和与方解石的结构关联，支持亲硫金属和硫在碱性系统中与碳酸盐一起流动的模型，该模型源自含水和碳酸化地幔源的低度部分熔化。Mordor 说明碱性火成岩是岩浆 Cu-Au-PGE-Ni 硫化物矿化的前景，经典的“边缘贱金属和富含硫化物”和“层状富含 PGE 和贫硫化物”的矿化类型都可能被发现在这样的入侵中。