The Fudian ore field in the southern North China Craton hosts the giant Donggou porphyry Mo deposit and several Pb-Zn-Ag vein deposits. Ore genesis of the Pb-Zn-Ag deposits and their relationships with the Donggou porphyry-related system are still controversial, which further restricts the regional prospecting and exploration. The Laodaizhanggou Pb-Zn-Ag deposit in the northwest of the ore field was focused in this study, to investigate its ore-forming age and genesis, and further to explore the implications for regional prospecting of Pb-Zn-Ag and Mo. The Pb-Zn-Ag veins at Laodaizhanggou are structurally controlled by the east-striking fault zones transecting the host volcanic rocks of Proterozoic Xiong’er Group. Field observations and textural relationships indicate that there are four paragenetic stages during ore-forming process, including the quartz-pyrite veins (stage I), siderite-polymetallic sulfide veins (stage II), ankerite-polymetallic sulfide veins (stage III), and quartz-calcite veins (stage IV). Ore-related sericite ⁴⁰Ar/³⁹Ar dating shows that the Pb-Zn-Ag mineralization at Laodaizhanggou was formed at 124.7±1.2 Ma. Carbonate minerals (siderite, ankerite, and calcite) have δ¹³C_PDB values of −9.1‰ to −3.9‰ and δ¹⁸O_SMOW of 12.1‰ to 15.6‰, corresponding to calculated values for the ore fluids of −8.0‰ to −2.8‰ and 4.9‰ to 10.1‰, respectively. These isotope values are in accordance with those of magmatic fluids. Sulfide minerals at Laodaizhanggou have δ³⁴S values of 5.3‰ to 10.1‰, and galena separates have ²⁰⁶Pb/²⁰⁴Pb ratios of 17.380 to 17.458, ²⁰⁷Pb/²⁰⁴Pb ratios of 15.459 to 15.485, and ²⁰⁸Pb/²⁰⁴Pb ratios of 38.274 to 38.370. Both S and Pb isotope data of Laodaizhanggou are consistent with those of the Donggou porphyry Mo deposit and distal Sanyuangou and Wangpingxigou Pb-Zn-Ag deposits, suggesting they share a similar magmatic origin. However, the Laodaizhanggou deposit was not the distal product of the giant Donggou porphyry-related magmatic-hydrothermal system, as the former is about 7 Ma older than the latter. The ore-forming age of Laodaizhanggou is consistent with that of the phase 1 magmatism of Taishanmiao batholith, indicating the Laodaizhanggou deposit is genetically related to ca. 125 Ma magmatism in the area. Combined the geochronological and geochemical data on Laodaizhanggou and the regional geological setting, we propose that the fracture systems in the northeast of the Taishanmiao batholith are potential sites for prospecting Pb-Zn-Ag deposit and the deep part among Laodaizhanggou, Xizaogou, and Liezishan is a target for prospecting porphyry Mo deposit.

华北克拉通南部的福甸矿田拥有巨大的东沟斑岩型钼矿床和若干铅锌锌银矿床。Pb-Zn-Ag矿床的成因及其与东沟斑岩相关系统的关系仍存在争议，这进一步限制了该地区的勘探和勘探。这项研究的重点是在矿田西北部的老大丈沟铅锌锌银矿床，以调查其成矿年龄和成因，并进一步探讨其对铅锌银钼矿的区域勘探的意义。老戴丈沟的铅锌锌银矿脉在构造上受东元断裂带的影响，该断裂带横切了元古代熊耳群的主火山岩。现场观察和构造关系表明，成矿过程中有四个共生阶段，包括石英黄铁矿脉（第I阶段），菱铁矿多金属硫化物脉（第II阶段），铁矿多金属硫化物脉（第III阶段）和石英方解石脉（第IV阶段）。矿石相关绢云母⁴⁰ Ar / ³⁹ Ar测年表明，老大丈沟的Pb-Zn-Ag矿化形成于124.7±1.2 Ma。碳酸盐矿物（菱铁矿，白云石和方解石）具有δ ^13个C ^ _PDB的值-9.1‰至-3.9‰和δ ¹⁸ ö _SMOW 12.1‰至15.6‰，对应于计算出的值的-8.0‰矿石流体-分别为2.8‰和4.9‰至10.1‰。这些同位素值与岩浆流体的同位素值一致。在Laodaizhanggou硫化物矿物具有δ ^34个的5.3‰的价值观至10.1‰，方铅矿中隔离具有²⁰⁶的Pb / ²⁰⁴的17.380到17.458的Pb的比率，²⁰⁷的Pb / ²⁰⁴铅比为15.459至15.485，以及²⁰⁸ Pb / ²⁰⁴铅比为38.274至38.370。老大丈沟的S和Pb同位素数据与东沟斑岩型钼矿床，三元沟末和王坪西沟末期Pb-Zn-Ag矿床一致，表明它们具有相似的岩浆成因。但是，老大丈沟矿床不是与东沟斑岩有关的巨大岩浆热液系统的末梢产物，因为前者比后者大了约7 Ma。老大丈沟矿的成矿时代与台山庙岩基一期岩浆作用的成矿年龄相符，表明老大丈沟矿床与成因有关。该地区125 Ma岩浆作用。结合老大丈沟的地质年代和地球化学数据以及区域地质环境，