Recognizing if and how Au is remobilized, in solid, melt, or fluid state, is critical for understanding the origin of high-grade ore zones in Au deposits. When evidence for Au remobilization can be demonstrated, then primary versus secondary processes can be distinguished, resulting in a more complete understanding of Au deposit formation. To address this, samples from two Au deposits, Jerome and Kenty, in the Archean Swayze greenstone belt of northern Ontario, Canada, together with archived samples from 39 high-grade Au deposits from the Abitibi greenstone belt across Ontario and Quebec, were geochemically characterized using integrated scanning electron microscopy-energy dispersive spectroscopy and electron microprobe imaging and analyses in addition to laser ablation-inductively coupled plasma-mass spectrometry elemental mapping. These data provided the basis to develop a model for Au remobilization and upgrading of Au that is widely applicable to orogenic gold settings.Data for the Jerome deposit indicate that Au uptake into early pyrite was not due to pulsing of different fluids, but instead was predominantly controlled by S availability, whereby the oscillatory/sector zoning in pyrite resulted from the substitution of As into S sites during rapid growth due to local chemical disequilibrium. In addition, Au-bearing pyrite from both the Jerome and Kenty deposits records textures, such as porosity development coincident with the presence of native gold and accessory sulfide phases, that are strongly suggestive of coupled dissolution-reprecipitation (CDR) reactions that liberated Au and associated elements from earlier auriferous (100–5,000 ppm Au) pyrite. During the remobilization process, Au and Ag were decoupled, which resulted in (1) a change in Au/Ag ratios of 0.5 to 5 in early pyrite to ≈9 in the new native gold (900 Au fineness) and (2) incorporation of Ag into cogenetic secondary mineral phases (e.g., chalcopyrite, tetrahedrite, and galena). Evidence for an association of low-melting point chalcophile elements (LMCE; Hg, Te, Sb, and Bi) with Au at the Jerome, Kenty, and many (>50%) of the 39 historic deposits sampled, along with native gold filling structurally favorable sites in vein quartz in all samples, indicates a fluid might not have been the only factor contributing to remobilization. This systematic Au-LMCE association strongly supports a model whereby Au is released by CDR reactions and is then remobilized by fluid-mediated, LMCE-rich melts that began to form at 335°C and/or by local, nanoparticle (nanomelt?) transport during deformation and metamorphism. Conclusions drawn from this study have implications for Au deposits globally and can account for the common presence of coarse-grained, commonly crystalline, native gold filling fractures in quartz and the paragenetically late-stage origin of gold in veins. They can also better explain the inability of Au in solution remobilization models to account for locally high gold grades, given the relatively low solubility of Au in hydrothermal fluids.

中文翻译：

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黄金动员：加拿大阿比蒂比省太古宙斯维兹绿岩带金矿的见解

识别是否以及如何以固态，熔融态或流体态迁移Au，对于理解Au矿床中高品位矿床的成因至关重要。当可以证明金转移的证据时，则可以区分主要过程和次要过程，从而更全面地了解金沉积物的形成。为了解决这个问题，对地球化学特征从加拿大北部安大略省的太古宙斯威兹绿岩带中的两个金矿Jerome和Kenty样品，以及来自安大略省和魁北克Abitibi绿岩带39个高品位金矿的归档样品进行了地球化学表征。除了使用激光烧蚀-电感耦合等离子体质谱法元素映射外，还使用集成扫描电子显微镜-能量色散光谱和电子显微探针成像和分析。这些数据为建立广泛适用于造山金环境的金迁移和金迁移模型提供了基础。杰罗姆矿床的数据表明，金被吸收到早期黄铁矿中并不是由于脉动不同的流体，而是主要是由于脉动的不同。硫的可控性决定了硫铁矿的振荡/扇形区划，这是由于局部化学不平衡而在快速生长过程中将砷代入了S位。此外，来自杰罗姆和肯蒂矿床的含金黄铁矿均记录了织构，例如与天然金和辅助硫化物相同时出现的孔隙度发展，这强烈暗示了释放金和铁的耦合溶解-再沉淀（CDR）反应。早期金铁矿（100-5,000 ppm的金）黄铁矿中的相关元素。在迁移过程中，Au和Ag解耦，这导致（1）早期黄铁矿的Au / Ag比值从0.5改变到5，而新的原生金（900 Au纯度）则变为≈9（2）。 Ag进入共生次生矿物相（例如，黄铜矿，四面体和方铅矿）。在杰罗姆，肯蒂和采样的39个历史性矿床中，有许多与低熔点亲硫族元素（LMCE; Hg，Te，Sb和Bi）和Au有关的证据，还有原生金填充在所有样品中，石英的结构上有利的部位都表明，流体可能不是促成迁移的唯一因素。这种系统的Au-LMCE关联强烈支持一种模型，该模型可通过CDR反应释放Au，然后通过流体介导，富含LMCE的熔体在335°C和/或在变形和变质过程中通过局部纳米颗粒（nanomelt？）传输开始形成。这项研究得出的结论对全球金矿具有重要意义，并且可以解释石英中粗粒，通常为晶体的原生金充填裂缝的普遍存在以及脉动中金的偏磁法晚期成因。考虑到金在水热流体中的相对较低的溶解度，他们还可以更好地解释溶液迁移模型中的金不能解释局部高金品位的问题。石英中的天然金填充裂缝和脉动中的偏微法后期金矿起源。考虑到Au在热液中的溶解度相对较低，他们还可以更好地解释在溶液迁移模型中Au不能解决局部高金品位的问题。石英中的天然金填充裂缝和脉动中的偏微法后期金矿起源。考虑到金在水热流体中的相对较低的溶解度，他们还可以更好地解释溶液迁移模型中的金不能解释局部高金品位的问题。