The Mt. Carlton Au-Ag-Cu deposit, northern Bowen basin, northeastern Australia, is an uncommon example of a sublacustrine hydrothermal system containing economic high-sulfidation epithermal mineralization. The deposit formed in the early Permian and comprises vein- and hydrothermal breccia-hosted Au-Cu mineralization within a massive rhyodacite porphyry (V2 open pit) and stratabound Ag-barite mineralization within volcano-lacustrine sedimentary rocks (A39 open pit). These orebodies are all associated with extensive advanced argillic alteration of the volcanic host rocks. Stable isotope data for disseminated alunite (δ34S = 6.3–29.2‰; δ18OSO4 = –0.1 to 9.8‰; δ18OOH = –15.3 to –3.4‰; δD = –102 to –79‰) and pyrite (δ34S = –8.8 to –2.7‰), and void-filling anhydrite (δ34S = 17.2–19.2‰; δ18OSO4 = 1.8–5.7‰), suggest that early advanced argillic alteration formed within a magmatic-hydrothermal system. The ascending magmatic vapor (δ34SSS ≈ –1.3‰) was absorbed by meteoric water (~50–60% meteoric component), producing an acidic (pH ≈ 1) condensate that formed a silicic → quartz-alunite → quartz-dickite-kaolinite zoned alteration halo with increasing distance from feeder structures. The oxygen and hydrogen isotope compositions of alunite-forming fluids at Mt. Carlton are lighter than those documented at similar deposits elsewhere, probably due to the high paleolatitude (~S60°) of northeastern Australia in the early Permian. Veins of coarse-grained, banded plumose alunite (δ34S = 0.4–7.0‰; δ18OSO4 = 2.3–6.0‰; δ18OOH = –10.3 to –2.9‰; δD = –106 to –93‰) formed within feeder structures during the final stages of advanced argillic alteration. Epithermal mineralization was deposited subsequently, initially as fracture- and fissure-filling, Au-Cu–rich assemblages within feeder structures at depth. As the mineralizing fluids discharged into lakes, they produced syngenetic Ag-barite ore. Isotope data for ore-related sulfides and sulfosalts (δ34S = –15.0 to –3.0‰) and barite (δ34S = 22.3–23.8‰; δ18OSO4 = –0.2 to 1.3‰), and microthermometric data for primary fluid inclusions in barite (Th = 116°– 233°C; 0.0–1.7 wt % NaCl), are consistent with metal deposition at temperatures of ~200 ± 40°C (for Au-Cu mineralization in V2 pit) and ~150 ± 30°C (Ag mineralization in A39 pit) from a low-salinity, sulfur- and metal-rich magmatic-hydrothermal liquid that mixed with vapor-heated meteoric water. The mineralizing fluids initially had a high-sulfidation state, producing enargite-dominated ore with associated silicification of the early-altered wall rock. With time, the fluids evolved to an intermediate-sulfidation state, depositing sphalerite- and tennantite-dominated ore mineral assemblages. Void-filling massive dickite (δ18O = –1.1 to 2.1‰; δD = –121 to –103‰) with pyrite was deposited from an increasingly diluted magmatic-hydrothermal liquid (≥70% meteoric component) exsolved from a progressively degassed magma. Gypsum (δ34S = 11.4–19.2‰; δ18OSO4 = 0.5–3.4‰) occurs in veins within postmineralization faults and fracture networks, likely derived from early anhydrite that was dissolved by circulating meteoric water during extensional deformation. This process may explain the apparent scarcity of hypogene anhydrite in lithocaps elsewhere. While the Mt. Carlton system is similar to those that form subaerial high-sulfidation epithermal deposits, it also shares several key characteristics with magmatic-hydrothermal systems that form base and precious metal mineralization in shallow-submarine volcanic arc and back-arc settings. The lacustrine paleosurface features documented at Mt. Carlton may be useful as exploration indicators for concealed epithermal mineralization in similar extensional terranes elsewhere.

中文翻译：

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早二叠世、湖底岩浆-热液系统的重建：澳大利亚东北部卡尔顿山浅成热液 Au-Ag-Cu 矿床

山 位于澳大利亚东北部博文盆地北部的卡尔顿金银铜矿床是一个不常见的湖底热液系统例子，其中包含经济的高硫化超热矿化。该矿床形成于早二叠世，包括在块状流纹英石斑岩（V2​​ 露天矿）内的脉状和热液角砾岩中的 Au-Cu 矿化和火山-湖相沉积岩（A39 露天矿）内的层状银重晶石矿化。这些矿体都与火山母岩的广泛晚期泥质蚀变有关。播散性明矾石（δ34S = 6.3–29.2‰；δ18OSO4 = –0.1 至 9.8‰；δ18OOH = –15.3 至 –3.4‰；δD = –102 至 –79‰）和黄铁矿（δ34S = –2.78.）的稳定同位素数据‰), 和填充空隙硬石膏 (δ34S = 17.2–19.2‰; δ18OSO4 = 1.8–5.7‰), 表明早期晚期泥质蚀变形成于岩浆-热液系统内。上升的岩浆蒸气 (δ34SSS ≈ –1.3‰) 被大气水 (~50–60% 大气成分) 吸收, 产生酸性 (pH ≈ 1) 冷凝物, 形成硅质 → 石英-明矾石 → 石英-地开石-高岭石分带随着与馈线结构距离的增加，蚀变晕。明矾石形成流体的氧和氢同位素组成。卡尔顿比其他地方类似矿床记录的要轻，这可能是由于早二叠世澳大利亚东北部的高古纬度 (~S60°)。粗粒带状羽状铝辉石矿脉（δ34S = 0.4–7.0‰；δ18OSO4 = 2.3–6.0‰；δ18OOH = –10.3 到 –2.9‰；δD = –106 到 –93‰）在最后阶段的馈线结构中形成先进的泥质改变。超热成矿随后沉积，最初是作为裂缝和裂隙充填、深部馈线结构内的富金铜组合。随着矿化流体排入湖泊，它们产生了同生银重晶石矿石。与矿石有关的硫化物和硫盐（δ34S = –15.0 至 –3.0‰）和重晶石（δ34S = 22.3-23.8‰；δ18OSO4 = –0.2 至 1.3‰）的同位素数据，以及重晶石中原生流体包裹体的微热数据（Th = 116°– 233°C；0.0–1.7 wt % NaCl)，与 ~200 ± 40°C（对于 V2 坑中的 Au-Cu 矿化）和 ~150 ± 30°C（在A39 坑）来自一种低盐度、富含硫和金属的岩浆热液，与蒸汽加热的大气水混合。矿化液最初处于高硫化状态，生产以磷灰石为主的矿石，并伴有早期蚀变围岩的硅化作用。随着时间的推移，流体演变为中等硫化状态，沉积以闪锌矿和天蓝长石为主的矿石矿物组合。充满空隙的块状地开石（δ18O = –1.1 至 2.1‰；δD = –121 至 –103‰）与黄铁矿是由逐渐稀释的岩浆热液（≥70% 陨石成分）从逐渐脱气的岩浆中溶出的沉积而成。石膏（δ34S = 11.4–19.2‰；δ18OSO4 = 0.5–3.4‰）出现在矿化后断层和裂缝网络内的脉中，可能来自早期硬石膏，在拉伸变形过程中被循环的大气水溶解。这个过程可能解释了其他地方石冠中亚生硬石膏的明显稀缺。虽然山。卡尔顿系统与形成海底高硫化浅成热液矿床的系统相似，也与在浅海火山弧和弧后环境形成贱金属和贵金属矿化的岩浆-热液系统具有几个关键特征。在 Mt. 记录的湖相古地表特征。卡尔顿可用作其他地方类似伸展地体中隐藏的超热液矿化的勘探指标。