The Archean low-grade, large-tonnage Côté Gold Au(-Cu) deposit is the first large gold deposit discovered in the Swayze greenstone belt, Ontario, Canada. The deposit is hosted by the Chester Intrusive Complex, a low-Al composite, subvolcanic intrusion composed of tonalite, quartz diorite, and diorite that was previously constrained to ca. 2741 to 2739 Ma (U-Pb zircon). Presented here is the first detailed study of the mineralization and related alteration, along with the relative and absolute age (U-Pb, Re-Os) constraints on gold mineralization.The earliest hydrothermal stage is represented by rare Au-bearing amphibole-rich veins and breccias. The main ore stage consists of biotite-rich alteration centered on an Au(-Cu)–bearing magmatic-hydrothermal biotite breccia body with spatially related disseminated biotite and veins of both sheeted and stockwork type. Extensive fracture-controlled and replacement-style Au ± Cu-bearing muscovite alteration overprints biotite-altered rocks in the core of the deposit. Barren fracture-controlled and disseminated epidote alteration is localized to the north of the deposit and above the magmatic-hydrothermal biotite breccia. Late, texturally destructive albite alteration overprints the mineralized hydrothermal alteration in the deposit core.U-Pb isotope dilution-thermal ionization mass spectrometry and laser ablation-inductively coupled plasmamass spectrometry ages for hydrothermal titanite from amphibole (2745 ± 3 Ma) and albite (2737.5 +2.2/–1.8, 2745 ± 9, and 2736 ± 7 Ma) alteration assemblages constrain hydrothermal activity to ca. 2740 Ma. The timing of gold and sulfide mineralization is also constrained by two Re-Os molybdenite ages of 2736.1 ± 11.4 (biotite alteration) and 2746.8 ± 11.4 Ma (muscovite alteration). These new ages overlap with the ca. 2741 to 2739 Ma magmatism for the Chester Intrusive Complex, thereby suggesting a synintrusion, magmatic-hydrothermal origin for the gold mineralization and related alteration. This is significant, as it represents a new gold metallogenic event in the Abitibi subprovince, for which regional importance remains to be defined.Considering the spatial association of the deposit with a dioritic intrusion and the temporal overlap of igneous activity with alteration (i.e., amphibole, biotite, sericite) and mineralization (i.e., breccias, veins, disseminations), the deposit is interpreted as an Archean magmatic-hydrothermal ore system sharing analogies with Phanerozoic Au-Cu porphyry deposits. It suggests that Archean porphyry-type deposits can form in low-Al composite intrusions, which are known to host Cu-Mo-Au breccia, vein, and disseminated mineralization and underlie temporally and genetically related felsic to intermediate volcanic rocks that host volcanogenic massive sulfide deposits.

中文翻译：

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太古代斑岩型金矿床：加拿大安大略省优越省Swayze绿宝石带的Côté金Au（-Cu）矿床

太古代低品位，大吨位的科特金金（-Cu）矿床是加拿大安大略省Swayze绿岩带中发现的第一批大型金矿床。该矿床由切斯特侵入复合岩（Chester Intrusive Complex）托管，这是一种低铝复合材料，次火山岩侵入体，由斜方晶石，石英闪长岩和闪长岩组成，以前被限制在约10％左右。2741至2739 Ma（U-Pb锆石）。此处是对金矿化及其相关蚀变的首次详细研究，以及金矿化的相对和绝对年龄（U-Pb，Re-Os）约束。最早的热液阶段是罕见的富金闪石和角砾岩。主要矿石阶段包括富含黑云母的蚀变，其中心是含Au（-Cu）岩浆热液黑云母角砾岩体，具有与空间相关的散布黑云母以及片状和储层类型的脉。广泛的裂缝控制和置换型的含Au±Cu的白云母蚀变覆盖了沉积岩芯中黑云母蚀变的岩石。贫瘠的裂缝控制和散布的埃迪奥蚀变蚀变位于矿床的北部和岩浆热液黑云母角砾岩的上方。后期构造破坏性的钠长石蚀变覆盖了沉积岩心中矿化的热液蚀变.U-Pb同位素稀释-热电离质谱和激光烧蚀-电感耦合等离子体质谱法分析了角闪石（2745±3 Ma）和钠长石（2737.5）的热液钛矿。 + 2.2 / –1.8，2745±9和2736±7 Ma）的蚀变组合将热液活动限制在 2740马。金和硫化物矿化的时间也受两个Re-Os辉钼矿年龄2736.1±11.4（黑云母蚀变）和2746.8±11.4 Ma（白云母蚀变）的影响。这些新时代与约。切斯特侵入岩群的2741至2739 Ma岩浆作用，因此暗示金矿化和相关蚀变的成岩作用，岩浆热液成因。这是重要的，因为它代表了阿比提比省的一个新的金成矿事件，尚需确定区域重要性。考虑到矿床与二闪性侵入的空间联系以及火成活动与蚀变的时间重叠（即闪石） ，黑云母，绢云母）和矿化作用（例如角砾岩，矿脉，分布），该矿床被解释为与古生代金铜斑岩矿床具有相似性的太古代岩浆-热液矿石系统。这表明太古宙斑岩型矿床可能形成于低铝复合侵入岩中，这些侵入岩以Cu-Mo-Au角砾岩，脉状和散布的矿化为宿主，并在时间上和遗传上与长石成因有关，为中伏火山岩的中部，火山岩中蕴藏着火山性块状硫化物。存款。