The Jiangnan orogen, one of the largest gold-producing areas in China, has experienced multiple orogenic events with complex structural overprinting that is marked by multiple stages of magmatism, deformation, metamorphism, and orogenic gold mineralization. Different orogenic events have been recognized in the Neoproterozoic, mid-Paleozoic, Triassic, and Early Cretaceous, reflecting collisions and intracontinental orogenic episodes. The age of gold deposition in the Jiangnan orogen, however, has been poorly constrained owing to the absence of suitable dating minerals. Field studies in the orogen indicate the Tuanshanbei gold deposit includes two generations of auriferous quartz-ankerite-pyrite-arsenopyrite veins (Q2 and Q3), with the latter of the two notable for containing more abundant ankerite and base metal sulfides. The Q2 veins were formed throughout the near S-N–directed shortening associated with D₁ deformation and along resulting subhorizontal to low-angle-dipping EW- to WNW-striking transpressive faults. The Q3 veins, containing about 70% of the total gold resource, were primarily localized in moderately to steeply dipping NW-striking tensional/tensional shear faults and moderately dipping NE- to NNE-striking transpressive faults that were products of NW-SE–directed shortening during D₂ deformation. Both vein generations are temporally younger than the 437.2 ± 4.2 Ma Tuanshanbei granodiorite host, and both are crosscut by postgold ca. 225 Ma diabase dikes.Hydrothermal monazite coexists with native gold and gold-bearing metal sulfides in the Q2 and Q3 veins. The Q2 monazite yielded a Tera-Wasserburg lower intercept age of 415.1 ± 2.1 Ma, consistent within error with an ankerite Sm-Nd isochron age of 410 ± 15 Ma and a laser ablation-inductively coupled plasma-mass spectrometry hydrothermal zircon ²⁰⁶Pb/²³⁸U age of 411.2 ± 4.0 Ma. The Q3 monazite yielded a Tera-Wasserburg lower intercept age of 234.3 ± 1.1 Ma. These new ages suggest that the Early Devonian gold event was overprinted by hydrothermal activity along the same structural system almost 200 m.y. later such that the gold resource must be a product of two temporally distinct events. Geologic and structural evidence, coupled with existing published geochemical data, suggests both ore-forming events were related to crustal metamorphism typical of most orogenic gold deposits. Fluids would have been derived from Neoproterozoic metasedimentary basement rocks, most likely from metamorphic devolatilization of the Neoproterozoic Cangxiyan Group greenschist-amphibolite facies metasediments. There is no evidence suggesting any type of magmatic contribution to the ore-forming process at either time. The data are best interpreted to suggest that various parts of the basement were metamorphosed near the greenschist-amphibolite boundary at different times, but during both times, the gold-bearing metamorphic fluids eventually migrated into the same structural conduits.

中文翻译：

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华南江南造山带中部团山北造山金矿床叠加金成矿事件

江南造山带是我国最大的金矿产区之一，经历了多次造山运动，构造叠印复杂，具有岩浆作用、变形作用、变质作用和造山金成矿作用等多期特征。新元古代、中古生代、三叠纪和早白垩世已认识到不同的造山事件，反映了碰撞和陆内造山事件。然而，由于缺乏合适的测年矿物，江南造山带金沉积的年龄一直很难确定。造山带实地研究表明，团山北金矿床包括两代含金石英-铁白云石-黄铁矿-毒砂矿脉（Q2 和 Q3），其中后者以含有更丰富的铁白云石和贱金属硫化物而闻名。 Q2 矿脉是在与 D ₁变形相关的近 SN 方向的缩短过程中形成的，并沿着由此产生的近水平到小角度倾斜的东西向至西北西向的压断断层形成。 Q3 矿脉约占总金资源量的 70%，主要集中在中度至陡峭的 NW 走向的张性/张性剪切断层和中度倾斜的 NE 至 NNE 走向的压断层中，这些断层是 NW-SE 向的产物。 D ₂变形期间缩短。两个矿脉代在时间上都比 437.2 ± 4.2 Ma 团山北花岗闪长岩主矿年轻，并且均被金后约 100 年前横切。 225 Ma辉绿岩岩脉。Q2、Q3矿脉中热液独居石与自然金及含金金属硫化物共存。 Q2 独居石产生的 Tera-Wasserburg 下截距年龄为 415.1 ± 2.1 Ma，与铁白云石 Sm-Nd 等时线年龄 410 ± 15 Ma 和激光烧蚀-电感耦合等离子体质谱水热锆石²⁰⁶ Pb/ ²³⁸的误差一致。U年龄为411.2±4.0Ma。 Q3 独居石的 Tera-Wasserburg 截距年龄较低，为 234.3 ± 1.1 Ma。这些新年龄表明，早泥盆世金矿事件在近 200 年后被沿同一构造系统的热液活动所覆盖，因此金矿资源必定是两个时间上不同的事件的产物。地质和结构证据，加上现有已发表的地球化学数据，表明这两种成矿事件都与大多数造山金矿典型的地壳变质作用有关。流体可能源自新元古代变沉积基岩，最有可能来自新元古代苍溪岩群绿片岩-角闪岩相变沉积岩的变质脱挥发分作用。没有证据表明这两个时期的成矿过程有任何类型的岩浆贡献。这些数据最好的解释是表明基底的各个部分在不同时间在绿片岩-角闪岩边界附近发生了变质，但在这两个时期，含金变质流体最终迁移到相同的构造管道中。