Late Triassic to Early Jurassic porphyry Cu mineralization is common in British Columbia, yet there are few age-equivalent porphyry occurrences in Yukon. This study presents new data for the enigmatic Carmacks Copper Cu-Au-Ag deposit in south-central Yukon, Canada, which is hosted in amphibolite facies metamorphic inliers within the Early Jurassic Granite Mountain batholith. Sulfide mineralization occurs mainly as net-textured bornite and chalcopyrite in leucosome, and as chalcopyrite ± pyrite blebs and disseminations in amphibolite and quartz-plagioclase-biotite schist. Several studies suggest that the Carmacks Copper deposit and the nearby Minto deposit are related to porphyry belts in British Columbia, but constraining the timing of alteration, mineralization, and metamorphism has been difficult.This study establishes a geologic and high-precision geochronologic framework for sulfide mineralization and its host rocks at the Carmacks Copper deposit, using Re-Os dating of molybdenite, and chemical abrasion-thermal ionization mass spectrometry (CA-TIMS) analysis of both whole zircon grains and laser-cut fragments of complexly zoned zircon grains. Our data indicate that the igneous protolith of the metamorphic inliers formed at 217.53 ± 0.16 Ma, followed by peak metamorphism at amphibolite facies at 205.82 ± 0.23 Ma, which occurred prior to Granite Mountain batholith emplacement but subsequent to Cu-Au-Ag mineralization of the protolith. An early phase of the Granite Mountain batholith was emplaced at 199.84 ± 0.14 Ma, followed by the main phase at 195 to 194 Ma. A second generation of metamorphic zircon in migmatite at 196.01 ± 0.12 Ma represents a partial melting event associated with Granite Mountain batholith emplacement.Two petrographically distinct populations of molybdenite are present in unstrained, net-textured copper sulfides. A sample dominated by strained molybdenite yielded an ¹⁸⁷Re/¹⁸⁷Os age of 212.5 ± 1.0 Ma, which represents the minimum mineralization age of the protolith. A sample dominated by euhedral grains yielded an ¹⁸⁷Re/¹⁸⁷Os age of 198.5 ± 0.9 Ma, constraining the maximum age of sulfide remobilization. These results indicate that primary mineralization is >212.5 Ma and potentially coeval with the ~217.5 Ma generation of Late Triassic magmatism. The mineralized protolith, best interpreted as the potassic alteration zone of a Late Triassic (~217–213 Ma) porphyry Cu-Au system, was metamorphosed to amphibolite facies at ~206 Ma, and subsequently migmatized during 200 to 194 Ma intrusion of the Granite Mountain batholith. The chalcopyrite-bornite-dominant assemblage in neosome precipitated from an immiscible Cu-Fe-S melt phase that partly consumed xenocrystic molybdenite and reprecipitated new molybdenite grains.The Carmacks Copper deposit and the related Minto deposit are remnants of a Late Triassic porphyry belt, where a significant fraction of the original metal endowment was likely lost through digestion of mineralized rocks by midcrustal magma in the Early Jurassic. These Yukon deposits are rare examples of metamorphosed porphyry Cu systems in the global geologic record, where rapid tectonic burial following mineralization was the principal factor in their preservation.

中文翻译：

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Carmacks铜Cu-Au-Ag矿床：加拿大育空地区Stikine弧斑岩铜矿系统的矿化和Postore巨化

三叠纪晚期至侏罗纪早期斑岩铜矿化在不列颠哥伦比亚省很普遍，但育空地区几乎没有年龄等效的斑岩发生。这项研究提供了加拿大育空中南部神秘的卡马克铜Cu-Au-Ag矿床的新数据，该矿床位于早侏罗纪花岗岩山岩床内的闪石岩相变质内层中。硫化物矿化主要发生在白质体中，是网状的褐铁矿和黄铜矿，在闪石和石英斜长石-黑云母片岩中以黄铜矿±黄铁矿起泡和散布。多项研究表明，不列颠哥伦比亚省的Carmacks铜矿床和附近的Minto矿床与斑岩带有关，但很难控制蚀变，矿化和变质的时间。这项研究使用辉钼矿的Re-Os定年以及整个锆石的化学磨蚀-热电离质谱（CA-TIMS）分析建立了Carmacks铜矿床硫化物矿化及其宿主岩的地质和高精度地质年代学框架。锆石颗粒和激光切割的碎片。我们的数据表明，变质内陆的火成原生质形成于217.53±0.16 Ma，随后在角砾岩相的峰变质为205.82±0.23 Ma，发生在花岗岩山岩基岩位居前但铜-金-银矿化之后。原生石。花岗岩山岩基岩的早期阶段为199.84±0.14 Ma，随后的主要阶段为195至194 Ma。蒙脱石中的第二代变质锆石为196.01±0。12 Ma代表与花岗岩山岩基位置有关的部分熔融事件。在未应变的网状硫化铜中存在两个岩相学上明显不同的辉钼矿。以应变辉钼矿为主的样品产生了¹⁸⁷ Re / ¹⁸⁷ Os的年龄为212.5±1.0 Ma，它表示原生岩的最小成矿年龄。以正方晶为主的样品的¹⁸⁷ Re / ¹⁸⁷Os年龄为198.5±0.9 Ma，这限制了硫化物迁移的最大年龄。这些结果表明，主要的矿化作用> 212.5 Ma，并可能与晚三叠世岩浆作用的〜217.5 Ma时代同时期。矿化的原生岩最好解释为晚三叠世（〜217–213 Ma）斑岩Cu-Au系统的钾质蚀变带，并在〜206 Ma处变质为闪石岩相，随后在侵入花岗岩的200至194 Ma期间发生了迁移。山基岩。新体中的黄铜矿-斑脱石占主导地位的组合是由不混溶的Cu-Fe-S熔体相沉淀而形成的，Cu-Fe-S混溶相部分地消耗了异晶辉钼矿和新的辉钼矿粒。在侏罗纪早期，中地壳岩浆对矿化岩石的消化作用可能会损失掉大部分原始金属资源。这些育空地区的沉积物是全球地质记录中稀有的斑岩型铜矿系统的罕见例子，矿化后快速的构造埋葬是其保存的主要因素。