Abstract The Reef Deposit is an anomalous Au Cu occurrence in the Paleoproterozoic terranes of northern Wisconsin, better known as host to significant Cu Zn volcanogenic massive sulfide (VMS) deposits. Previous work using lead isotopes and fluid inclusions has identified a protracted development of the mineralization from initial formation as the root zone veins of a VMS deposit during the Penokean orogeny (~1.9–1.8 Ga), with the most recent mineralization/remobilization activity associated with late Paleozoic Mississippi Valley-type (MVT) fluid flow (Haroldson et al., 2018a, 2018b). Here we use the oxygen isotope history of the Reef Deposit to verify and further examine the deposit's protracted development. Laser fluorination oxygen isotope measurements of primary mineralized quartz veins range in δ18O from 6.8 to 10.0‰ (VSMOW), and a trend is observed of increasing δ18O values of parallel vein zones along a 400-m traverse from northwest to southeast, likely from a temperature gradient during initial formation. Temperature estimates for a VMS deposit setting (230 to 400 °C) are consistent with a hydrothermally shifted formation fluid, using seawater δ18O estimates during the Penokean Orogeny and evolving to higher δ18O by incorporation of magmatic fluids or interaction with local crust. In situ oxygen isotope measurement by Secondary Ion Mass Spectrometer (SIMS) of cross-cutting quartz and carbonate range in δ18O from 19.4 to 28.4‰ for quartz, 25.3 to 28.1‰ for dolomite, and 9.6 to 29.3‰ (VSMOW) for calcite. High δ18O values (>19‰) are measured in a crustiform-textured quartz stockwork microveinlet, in dolomite observed in late carbonate microveinlets, and calcite in settings associated with the late quartz and dolomite and a separate calcite-only setting directly linked with gold mineralization/remobilization.

中文翻译：

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SIMS氧同位素表明显生宙流体渗透了前寒武纪金矿床

摘要 Reef 矿床是威斯康星州北部古元古代地体中的一个异常 Au Cu 矿床，更为人所知的是重要的 Cu Zn 火山成因块状硫化物 (VMS) 矿床的宿主。先前使用铅同位素和流体包裹体的工作已经确定，在 Penokean 造山运动（~1.9-1.8 Ga）期间，作为 VMS 矿床根区脉的初始形成矿化的长期发展，最近的矿化/再动员活动与晚古生代密西西比河谷型 (MVT) 流体流动（Haroldson 等人，2018a，2018b）。在这里，我们使用 Reef 矿床的氧同位素历史来验证和进一步检查矿床的长期发展。δ18O 中原生矿化石英脉的激光氟化氧同位素测量范围为 6.8 至 10.0‰ (VSMOW)，并且观察到平行脉带的δ18O值沿着从西北到东南的400米横断面增加的趋势，可能是由于初始形成期间的温度梯度。VMS 矿床环境（230 至 400 °C）的温度估计值与热液转移地层流体一致，在 Penokean 造山运动期间使用海水 δ18O 估计值，并通过结合岩浆流体或与局部地壳相互作用演变为更高的 δ18O。通过二次离子质谱仪 (SIMS) 对 δ18O 中的横切石英和碳酸盐范围进行原位氧同位素测量，石英为 19.4 至 28.4‰，白云石为 25.3 至 28.1‰，方解石为 9.6 至 29.3‰ (VSMOW)。高 δ18O 值 (>19‰) 在壳状纹理石英网状微脉中测量，在晚期碳酸盐微脉中观察到的白云岩中，