The Zhengchong gold deposit is located in the central segment of the Jiangnan Orogen in northeastern Hunan Province, South China. The host rocks of this deposit are the Neoproterozoic slates of the Lengjiaxi Group and granodiorite. The structures in the Zhengchong gold deposit are dominated by NE-trending reverse faults, which control the gold-bearing veins. The orebody consists of NE-trending laminated quartz veins and NW-trending quartz veins. The alteration styles include silicification, carbonatization, sulfidation, sericitization and chloritization. The Zhengchong gold mineralization can be divided into four stages: Quartz-pyrite (stage I), quartz-pyrite-arsenopyrite (stage II), quartz-polysulfide (stage III) and quartz-carbonate (stage IV). Three generations of hydrothermal pyrite were identified: Disseminated euhedral to subhedral cubes in altered wall-rock (PyI), euhedral to subhedral cubes inter-grown with arsenopyrite and tetrahedrite in quartz veins and wall-rock (PyII), and euhedral cubes with microinclusions (native gold, galena, sphalerite, chalcopyrite, tetrahedrite, and pyrrhotite) or metasomatic textures in sulfide-rich veins or veinlets (PyIII). PyII and PyIII are arsenian pyrite and represent the main Au-bearing minerals. PyI records the lowest concentrations of Au; PyII and PyIII record similar amounts of Au, Cu, Pb, Zn, and Bi, but PyIII is more enriched in Co, Ni, Te, and Se. The substitution of As, Se and Te for S and that of Co and Ni for Fe occurs by direct-ion exchange. Invisible gold is uniformly distributed within the arsenian pyrite, and visible gold fills microfractures in PyII or occurs as inclusions in PyIII. Co, Ni, Cu exhibit positive correlations with Au and a negative correlation between Au + Cu + Co + Ni and Fe reflect that Fe vacancies may have been a major cause of the precipitation of invisible Au and other metal elements in pyrite structure. There are systematic trace element differences between the three generations of pyrite (PyI, PyII, PyIII). The more Co, Ni and Se, Te substitution that occurred for Fe and S, respectively, the greater the increase in the Co/Ni ratio (<1) and the decrease in the Se/Te ratio (<10) in stage III, indicating that a more reduced, lower-temperature metamorphic hydrothermal fluid was present in stage III.

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.

The Dongguashan copper (gold) deposit in Anhui Province is one of the largest copper (gold) deposits in the Tongling ore district, which is the most important region in the Middle–Lower Yangtze River Metallogenic Belt, Eastern China. Stratiform and lamellar orebodies are the major deposit types. Pyrite and pyrrhotite from the stratiform deposit type (Py I, Po I) and lamellar deposit type (Py II, Po II) are investigated using Electron-probe Microanalyses (EPMA) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Py I, Py II, Po I and Po II have high contents of Cu, Co, Au and Se, low contents of As, Pb and Zn, with Co/Ni ratios of 0.50−48.00, 4.00−45.00, 1.55−14.45 and 1.02−1.36, respectively, most of which are greater than 1 and vary widely; these characteristics are consistent with those of pyrite with a magmatic–hydrothermal origin. The higher Au/Ag and Fe/(S + As) ratios of pyrite and crystallization temperatures (286–387 °C) of hexagonal pyrrhotite indicate that the mineralization occurrs in environments with medium- to high-temperatures, high sulfur fugacity and medium-shallow depths. Therefore, we suggest that the Dongguashan copper (gold) deposit is a stratabound skarn-type ore deposit associated with magma intrusion activity during the Yanshanian Period.

The large Yongping Cu deposit is situated in the eastern Qin-Hang Metallogenic Belt, Southeast China and on the southern side of the Yangtze—Cathaysia suture zone, and is characterized by large stratiform orebodies. Garnet represents the main non-metallic mineral at Yongping, and shows variations in color from dark red to green to light brown with distance from the Shizitou porphyritic biotite granite stock. An in situ elemental analysis using EPMA and LA-ICP-MS and fluid inclusions microthermometric measurement on the Yongping garnet were conducted to constrain the hydrothermal and physicochemical mineralization conditions and the ore origin. The Yongping garnet ranges from nearly pure to impure andradite, is characterized by low concentrations of MnO (0.11–0.71 wt %) with a wide range of Y/Ho (2.1–494.9) and does not exhibit any melting inclusions or fluid-melt inclusions, indicating that they are likely to be resulted from hydrothermal replacements. The Yongping garnet is rich in LREEs, Cs, Th, U and Pb; relatively depleted in HREEs, Rb, Sr and Ba; but exhibits distinct Eu anomalies (δEu of the dark red, green and light brown garnet range 2.12–20.54, 0.74–1.70 and 0.52–0.85, respectively) with the homogenization temperatures and salinities of the fluid inclusions principally ranging from 387–477 °C and 7.8–16.0 wt % NaCl equivalent, respectively. The distinct trace elements and microthermometric characteristics reveal that the garnet was formed in a physicochemical conditions of medium-high temperature, 44–64 MPa pressures, mildly acidic pH levels, and unstable oxygen fugacity, and indicate that they were primarily formed by infiltration metasomatism, quite fitting with the scenario that the preferential entrance of magmatic-hydrothermal fluids derived from the Shizitou stock into the relatively low-pressure fracture zones between the limestone and quartz sandstone in the Yejiawan Formation, and further led to the formation of the Yongping stratiform mineralization.