The large Hebaoshan gold deposit (41.5 t Au, average grade: 3.5 g/t) is located in a hitherto poorly documented gold province in the northeastern part of the South China Block. It is hosted by Precambrian metasedimentary rocks that experienced Triassic greenschist- to amphibolite-facies metamorphism. Three hydrothermal stages can be distinguished: quartz + sericite + pyrite + pyrrhotite (stage I), quartz + magnetite + sulfide (stage II), and quartz + carbonate + pyrite + hematite (stage III). Auriferous pyrite samples yielded a Rb-Sr isochron age of 234 ± 3 Ma (2σ, MSWD = 0.24), and ore-related hydrothermal sericite yielded a ⁴⁰Ar-³⁹Ar plateau age of 226.4 ± 2.0 Ma (2σ, MSWD = 1.01), which are distinctly younger than ca. 430 Ma granitic rocks in the mining district and older than 170–130 Ma granites in the region, ruling out any genetic link between granite emplacement and gold mineralization. The mineralizing fluid system can be described as carbonic-aqueous with low to moderate salinity (2.2–10.1 wt% NaCl equiv.) and medium temperature of 290 to 350 °C (stage I) and 230 to 280 °C (stage II). The δ¹⁸O quartz ranges from 13.3 to 15.4 ‰, and the δD values for fluid inclusions in quartz range from − 97 to − 60 ‰. The calcite has C-isotopes ranging from − 6.1 to − 3.8 ‰ and O-isotopes from 2.8 to 13.6 ‰. H-O-C isotope data are consistent with a metamorphic fluid derived from devolatilization of Neoproterozoic basement rocks during regional metamorphism in the Late Triassic Indosinian period. The δ³⁴S values of sulfides for stages I, II, and III are 0.1 to 7.8 ‰, − 10.6 to 5.1 ‰, and − 18.9 to − 14.1 ‰, respectively, indicating an increase in oxygen fugacity during fluid ascent which resulted in more negative sulfur isotope values of sulfides and precipitation of gold. Pyrite separates have ²⁰⁶Pb/²⁰⁴Pb ratios of 17.340 to 17.687, ²⁰⁷Pb/²⁰⁴Pb ratios of 15.539 to 15.604, and ²⁰⁸Pb/²⁰⁴Pb ratios of 37.749 to 38.094. The S-Pb isotope data suggest derivation of S and Pb from the Precambrian metasedimentary country rocks. Auriferous pyrite yielded elevated ³He/⁴He ratios (0.78–1.46 Ra), which suggest a mantle component as can be expected from fluids derived from a subduction setting. It is concluded that Hebaoshan is an orogenic gold deposit that formed during Triassic flat-slab subduction of the paleo-Pacific plate beneath the South China Block and thus constitutes the first Triassic deposit of this type recognized in the coastal area of Southeast China.

大型的河宝山金矿（41.5吨金，平均品位：3.5克/吨）位于华南地块东北部迄今文献记载很少的黄金省。它由经历了三叠纪绿片岩-闪石相变质作用的前寒武纪沉积沉积岩所包裹。可以区分三个水热阶段：石英+绢云母+黄铁矿+硫铁矿（第一阶段），石英+磁铁矿+硫化物（第二阶段）和石英+碳酸盐+黄铁矿+赤铁矿（第三阶段）。黄铁矿样品的Rb-Sr等时年龄为234±3 Ma（2σ，MSWD = 0.24），矿石相关的水热绢云母产生⁴⁰ Ar- ³⁹Ar高原年龄为226.4±2.0 Ma（2σ，MSWD = 1.01），明显比ca年龄年轻。矿区中的430 Ma花岗质岩石以及该地区的170-130 Ma以上的花岗岩，排除了花岗岩矿床与金矿化之间的任何遗传联系。矿化流体系统可以说是含碳盐水溶液，具有低至中度的盐度（2.2-10.1 wt％NaCl当量），中温为290至350°C（第I阶段）和230至280°C（第II阶段）。该δ ¹⁸O石英的范围为13.3到15.4‰，石英中流体包裹体的δD值为-97到-60‰。方解石的C同位素范围为-6.1至-3.8‰，O同位素范围为2.8至13.6‰。HOC同位素数据与三叠纪印支期晚期区域变质过程中新元古代基底岩石脱挥发分所产生的变质流体相一致。的δ ³⁴硫化物为阶段的价值观I，II，和III是0.1〜7.8‰， - 10.6 5.1‰， - 18.9至- 14.1‰，分别指示流体在上升过程中在氧逸度的增加，这导致更硫化物的负硫同位素值和金的沉淀。黄铁矿中隔离具有²⁰⁶的Pb / ²⁰⁴的17.340铅比率17.687，²⁰⁷铅/ ²⁰⁴的15.539铅比率15.604，和²⁰⁸的Pb / ²⁰⁴的37.749铅比率38.094。S-Pb同位素数据表明，S和Pb来自前寒武纪准沉积的乡村岩石。黄铁矿产生的³ He / ⁴ He比值升高（0.78-1.46 Ra），这暗示着俯冲环境中的地幔成分。结论是，河宝山是在华南地块以下古太平洋板块的三叠纪平板俯冲过程中形成的造山型金矿床，是我国东南沿海地区公认的第一类三叠纪金矿床。