The McArthur River (HYC) Zn-Pb-Ag deposit in the Carpentaria Zn belt, northern Australia, is one of the world’s largest and most studied sediment-hosted base metal deposits, owing to its lack of deformation and preservation of sedimentary and ore textures. However, the ore formation process (syngenetic vs. epigenetic) is still a subject of controversy. In this paper we focus on key characteristics of the HYC deposit that remain unexplained: preservation of sedimentary carbonate (dolomite) and its association with Zn, and the role of thallium (Tl) and manganese (Mn) distribution in the orebody.Our findings demonstrate a sequence of events during ore formation: Tl is hosted almost exclusively within euhedral pyritic overgrowths around early diagenetic pyrite; sphalerite mineralization occurred after Tl-bearing pyrite overgrowths, in association with acid dissolution (replacement) of laminated and nodular dolomite across the subbasin; and outer rims are enriched in Mn on preserved dolomite at the dissolution reaction front in contact with sphalerite. New thermodynamic fluid chemistry modeling demonstrates the metal distribution and paragenesis can be explained by acidic, oxidized ore fluids entering the pyrite-dolomite host lithology, allowing reduction and pH buffering by acid carbonate dissolution, resulting in stepwise metal deposition in an evolving fluid.We argue this represents strong evidence for epigenetic ore formation at HYC. Furthermore, the primary control on ore deposition is not synsedimentary faulting in the subbasin; rather, the chemical potential of sedimentary carbonate within reduced, sulfidic lithologies appears to be of critical importance to precipitation of sphalerite.

中文翻译：

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碳酸盐替代是澳大利亚元古代麦克阿瑟河（HYC）沉积物沉积的Zn-Pb矿床的主要成矿过程。

澳大利亚北部Carpentaria Zn带中的麦克阿瑟河（HYC）Zn-Pb-Ag矿床，由于其缺乏形变以及缺乏沉积物和矿石质地的保存，是世界上最大，研究最多的沉积物为主的贱金属矿床之一。 。然而，成矿过程（同生与表生）仍是一个有争议的话题。在本文中，我们重点关注尚未解释的HYC矿床的关键特征：沉积碳酸盐（白云石）的保存及其与Zn的关系以及th（Tl）和锰（Mn）在矿体中的分布作用。矿石形成过程中的一系列事件：T1几乎完全被容纳在成岩黄铁矿周围的正铁黄铁矿过度生长中；含Tl的黄铁矿过度生长后发生闪锌矿矿化，与横跨盆地的层状和球状白云石的酸溶（置换）有关；外缘在与闪锌矿接触的溶解反应前沿，在保存的白云石上富集了Mn。新的热力学流体化学模型表明，金属的分布和共生可以用进入黄铁矿-白云石主体岩性的酸性，氧化矿石流体来解释，从而可以通过酸性碳酸盐溶解来还原和缓冲pH，从而导致金属在不断演化的流体中逐步沉积。这为HYC形成表观成因的矿石提供了有力的证据。此外，对矿床沉积的主要控制不是在盆地中的同生断层。相反，沉积碳酸盐内部的化学势降低了，