The polymetamorphosed Swartberg Cu-Pb-Zn-Ag deposit in the Namaqua Metamorphic Province of South Africa is a major metal producer in the region, yet its genesis remains poorly understood. The deposit comprises several stratiform to stratabound units, namely the Lower Orebody and Dark Quartzite, the overlying Barite Unit, and the Upper Orebody, all of which are folded by an F₂ isoclinal syncline and refolded by an open F₃ synform. A discordant Garnet Quartzite unit surrounds the Upper Orebody in the F₂ hinge, where it overprints the Lower Orebody and Barite Unit. The Lower Orebody comprises sulfidic, pelitic lenses with fine-grained pyrite, sphalerite, galena, and lesser pyrrhotite, hosted by sulfide-poor but magnetite- and barite-bearing siliceous rock. The overlying Barite Unit is poorly mineralized and grades from massive magnetite-barite close to the F₂ hinge to distal laminated baritic schist and quartzite. The Dark Quartzite is the stratigraphic equivalent of the Lower Orebody and Barite Unit but comprises siliceous quartzite and schist, with lenses of conglomerate and minor Fe-Mn-Zn phases. The Upper Orebody displays rapid zonations from massive magnetite-rich iron formation in the F₂ hinge, rich in coarse galena, pyrrhotite, and chalcopyrite, to sulfide-poor, magnetite-bearing schist and quartzite. The Garnet Quartzite is dominated by quartz and almandine garnet and mineralized with pyrite and chalcopyrite. Geochemical discriminant plots show that the Lower Orebody has a significant detrital component, whereas the Upper Orebody and Barite Unit are strongly zoned, with the greatest chemogenic component close to the F₂ hinge. This corresponds to a deposit-scale metal zonation from the Cu-rich F₂ hinge to more Pb- and then Zn-dominated areas. Mineral assemblages and paleoredox proxies suggest generally oxic conditions, with a more reduced signature close to the hinge and in the sulfidic Lower Orebody lenses.The Lower Orebody is interpreted as a mixed chemogenic-pelitic unit, with sulfides deposited on or near the seafloor during stage 1 hydrothermal activity. The sulfidic lenses formed from fine mud and clay deposited in quiet seafloor depressions, in which warm, dense, reducing, Pb-Zn-Ba–rich stage 1 brines accumulated, while the siliceous portions formed from higher-energy clastic sediments on aerated seafloor highs. The Barite Unit forms a baritic cap to the Lower Orebody, while the Dark Quartzite is their shallower-water equivalent. Thereafter, clastic sediment with lesser hydrothermal input was deposited during stage 2a exhalations, forming the poorly mineralized portions of the Upper Orebody. During stage 2b hydrothermal activity, hot Cu-Fe–rich fluids invaded part of the Upper Orebody, creating the highly chemogenic protolith to the well-mineralized, magnetite-rich portion. Associated hydrothermal alteration in a discordant subseafloor feeder zone created the Garnet Quartzite protolith. The F₂ hinge thus corresponds closely to the original vent zone.Swartberg therefore resembles a deformed and metamorphosed Selwyn-type sedimentary exhalative deposit, with both proximal- (Upper Orebody, Garnet Quartzite) and distal-style (Lower Orebody) mineralization. The close association of these styles suggests that differences in the mineralizing fluids and depositional environment, rather than proximity to a vent, determine the deposit style.

中文翻译：

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南非Aggeneys-Gamsberg矿区变质中生代Swartberg贱金属矿床的多阶段遗传模型。

南非纳马夸变质省的多变型Swartberg铜-铅-锌-银矿床是该地区的主要金属生产商，但其成因仍知之甚少。该矿床包括几个层状至层状结合的单元，即下矿体和深色石英岩，上覆重晶石单元和上矿体，所有这些均被F _2等斜向斜折叠，并被开放的F _3同形物重折叠。F _2中的上部矿石体周围环绕着不和谐的石榴石石英岩单元铰链，在那里叠印了下矿体和重晶石单元。下矿体由硫化物，珍珠岩晶状体组成，具有细粒黄铁矿，闪锌矿，方铅矿和次黄铁矿，由硫化物含量低但磁铁矿和重晶石的硅质岩构成。上覆的重晶石单元矿化程度较差，其等级从接近F ₂铰链的块状磁铁矿-重晶石到远端的层状重晶岩片岩和石英岩。深色石英岩与下矿体和重晶岩单元的地层等效，但由硅质石英岩和片岩组成，具有砾岩和次要的Fe-Mn-Zn相。上矿体在F _2中显示出大量块状富磁铁矿铁形成的快速地带铰链，富含粗方铅矿，黄铁矿和黄铜矿，富含硫化物，含磁铁矿的片岩和石英岩。石榴石石英岩以石英和金刚玉石榴石为主，并以黄铁矿和黄铜矿矿化。地球化学判别图显示，下矿体具有明显的碎屑成分，而上矿体和重晶石单元则被强烈划分，最大的化学成因成分靠近F ₂铰链。这对应于富铜F ₂的沉积规模金属带化铰接至更多的Pb和Zn为主的区域。矿物组合和古氧代烷通常表明有氧条件，靠近铰链和硫化的下部Orebody透镜中的特征减弱，下部Orebody被解释为混合的化学成因-石蜡单元，在此阶段硫化物沉积在海底或附近1热液活动。硫化物晶状体由沉积在安静的海底凹陷中的细泥和粘土形成，其中富含温暖，致密，还原性的富含Pb-Zn-Ba的第一阶段盐水，而硅质部分则由充气的海底高处的高能碎屑沉积物形成。重晶石单元形成了下矿体的重晶岩​​盖，而深色石英岩是它们的浅水当量。此后，在阶段2a呼气期间沉积了热液输入较少的碎屑沉积物，形成上矿体的矿化程度差的部分。在阶段2b的热液活动中，富含铜铁的热流体侵入了上矿体的一部分，为矿化度高，磁铁矿丰富的部分形成了具有高度化学原性的原生岩。在不协调的海底馈线区中进行了相关的热液蚀变，形成了石榴石石英岩原岩。F因此，_2个铰链与原始的出风口区域紧密对应.Swartberg因此类似于变形和变质的Selwyn型沉积呼出沉积物，近端（上矿体，石榴石石英岩）和远端型（下矿体）都有矿化作用。这些类型的密切联系表明，矿化流体和沉积环境的差异决定了沉积类型，而不是靠近喷口。