Abstract The Daero Paulos porphyry copper prospect, in the Asmara region of the central Eritrean highlands, is part of the Nakfa tectono-stratigraphic terrane, which, along with four other major and several minor terranes that constitute the Neoproterozoic Arabian-Nubian Shield, is characterized by juvenile, intra-oceanic island-arc crust. Alteration and mineralization at Daero Paulos occupy a north-northeast-trending corridor of multiphase, rhyolitic to dacitic intrusions emplaced into mafic and intermediate volcanic and subvolcanic rocks and derivative volcaniclastic strata. New U-Pb geochronological data for the volcanic rocks in the region confirm a >860-Ma age for the Neoproterozoic (Tonian) host sequence. The porphyry copper alteration evolved from early epidote-chlorite-albite through sericite-chlorite to late quartz-sericite. Local advanced argillic alteration is the erosional remnant of the lithocap that formerly dominated the shallowparts of the Daero Paulos system. A post-mineralization, Alaskan-type pyroxenite-gabbro body intruded the porphyry copper corridor, and is interpreted as the feeder for mafic dikes along the periphery of the porphyry copper system. Re-Os ages of 881.0±5.5 and 864.2±3.6 Ma for molybdenite from veinlets at Daero Paulos constrain an early Tonian timing for porphyry copper formation during early opening of the Mozambique Ocean after Rodinian supercontinent break-up. The ages also imply a rapid transition from initial rifting to the start of subduction and consequent establishment of an intra-oceanic island arc in what is now the Nakfa terrane. The molybdenite ages show that Daero Paulos is currently the oldest dated mineralization in the Arabian-Nubian Shield, and ~60–200 and, possibly, ~250 m.yr. older than porphyry copper mineralization elsewhere in the Shield. However, volcanogenic massive sulfide (VMS) mineralization could have been forming at broadly the same time, albeit not genetically associated with Daero Paulos. Preservation of such shallowly formed Neoproterozoic mineralization is mainly attributed to burial beneath thick post-amalgamation volcano-sedimentary basinal cover, collision-generated thrust sheets, and later Phanerozoic strata.

中文翻译：

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阿拉伯-努比亚地盾的成矿开始：Daero Paulos 斑岩铜矿勘探区，厄立特里亚

摘要 厄立特里亚中部高地阿斯马拉地区的 Daero Paulos 斑岩铜矿勘探区是 Nakfa 构造地层的一部分，与构成新元古代阿拉伯-努比亚地盾的其他四个主要和几个次要地体一起具有特征由年轻的大洋内岛弧地壳形成。Daero Paulos 的蚀变和矿化占据了一条多相、流纹质至英安质侵入体的北-东北走向走廊，侵入基性和中间火山岩和亚火山岩以及衍生火山碎屑岩地层。该地区火山岩的新 U-Pb 年代学数据证实了新元古代（Tonian）宿主序列的年龄 >860-Ma。斑岩铜蚀变由早期绿帘石-绿泥石-钠长石经绢云母-绿泥石演化至晚期石英-绢云母。局部晚期泥质蚀变是以前主导 Daero Paulos 系统浅层的岩盖的侵蚀残余物。矿化后的阿拉斯加型辉石辉长岩体侵入斑岩铜廊道，被解释为斑岩铜系外围基性岩脉的馈源。来自 Daero Paulos 细脉的辉钼矿的 Re-Os 年龄为 881.0±5.5 和 864.2±3.6 Ma，限制了在罗迪尼亚超大陆分裂后莫桑比克海洋早期开放期间斑岩铜形成的早期托尼阶时间。这些年龄还意味着从最初的裂谷到俯冲开始的快速转变，并随后在现在的纳克法地体中建立了洋内岛弧。辉钼矿年龄表明 Daero Paulos 是目前阿拉伯-努比亚地盾中年代最久的矿化，约 60-200 年，可能约 250 年。比地盾中其他地方的斑岩铜矿化还要古老。然而，火山成因块状硫化物 (VMS) 矿化可能大致同时形成，尽管在遗传上与 Daero Paulos 无关。这种形成浅层的新元古代成矿的保存主要归因于厚厚的混杂后火山-沉积盆地盖层、碰撞产生的冲断层和后来的显生宙地层下的埋藏。尽管在基因上与 Daero Paulos 无关。这种形成浅层的新元古代成矿的保存主要归因于厚厚的混杂后火山-沉积盆地盖层、碰撞产生的冲断层和后来的显生宙地层下的埋藏。尽管在基因上与 Daero Paulos 无关。这种形成浅层的新元古代成矿的保存主要归因于厚厚的混杂后火山-沉积盆地盖层、碰撞产生的冲断层和后来的显生宙地层下的埋藏。