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The Shangshan'gang Au deposit is located in the Cretaceous Dongkeng volcanic basin of northern Fujian Province in southeast China. The deposit is hosted by altered intermediate to silicic volcanic rocks along NE–SW- and ENE–WSW-trending faults. The main types of wall-rock alteration are silicification, sericitization, argillization, and chloritization. Ore mineralization occurred in three stages, which were the base metal, Au Ag, and post-ore stages. Electrum and kustelite are the main Au Ag minerals. Laser ablation–inductively coupled plasma–mass spectrometry analyses revealed different compositions for the two stages of pyrite, galena, and sphalerite, which reflect changing mineralization conditions. Fluid inclusions revealed an epithermal mineralization environment with low–moderate temperature and salinity. Mixing of ore fluids is the main ore-forming mechanisms which occurred from the early to late stages, as evidenced by the H and O isotopic compositions of the ore-forming fluids. The proportion of meteoric fluid in the ore-forming hydrothermal fluid gradually increased with time. Fluid boiling may have locally occurred in the early stage and promoted ore precipitation. Our results show that the Shangshan'gang Au deposit is an intermediate-sulfidation-type epithermal deposit that gradually changed to a low-sulfidation-type during late mineralization. Given the close temporal and spatial relationship between intermediate-sulfidation-type and porphyry deposits, there is potential for porphyry deposits to exist in the Zhenghe–Jian'ou area. • An intermediate-sulfidation genesis was proposed to the Shangshan'gang deposit. • In-situ major and trace element of sulfides reveals divers mineralization conditions. • Ore-forming fluid were characterized by low-medium temperature and salinity fluids. • Mineralization was induced by mixing of dominant meteoric and minor magmatic fluids. [ABSTRACT FROM AUTHOR]

• The Xiaban gold deposit is a low-sulfidation epithermal gold deposit. • Dominated by a quartz + sericite + illite + chalcedony alteration assemblage. • Mineralization was formed from low-temperature and low-salinity fluids. • Isotope data indicate that ore-forming fluids were predominantly of meteoric origin. • Gold deposition was caused by mixing of dominant meteoric and minor magmatic fluids. The Xiaban gold deposit is located in the Dehua goldfield of central-eastern Fujian Province, southeast China. Detailed field observations combined with mineral exploration in the study area indicate that the majority of mineralization within the Xiaban gold deposit is hosted by porphyritic rhyolite units in areas proximal to E–W trending faults with lesser amounts located within alteration zones along lithological contacts. The deposit contains silicified banded, disseminated, brecciated, fine-grained stockwork, and quartz–sulfide vein-hosted mineralization, all of which is associated with a quartz–sericite–illite–chalcedony alteration assemblage. The main ore minerals are electrum and pyrite with lesser amounts of galena, Fe-rich sphalerite, and marcasite, all of which are associated with sericitic and argillic alteration as well as silicification. Fluid inclusion microthermometric analysis of quartz-hosted fluid inclusions associated with the main stage of mineralization yielded homogenization temperatures (T h) of 157–207 °C (mean of 180 °C) and salinities of 0.7–2.9 wt% NaCl equivalent, which are indicative of an epithermal-type system. The precipitation of gold was most likely caused by fluid mixing between dominant meteoric and minor magmatic fluid components. Fluids within quartz-hosted fluid inclusions have H and O isotopic compositions (δD H2O = −106.3‰ to −81.8‰; δ18O H2O = −5.8‰ to −3.0‰) that are indicative of ore-forming fluids derived from a meteoric-water-dominated source. Pyrite in the study area has S isotopic compositions that vary between −2.8‰ and −1.6‰, indicative of S derived from a homogeneous magmatic source. Lead isotopic compositions of the pyrite within the deposit (206Pb/204Pb = 18.2953–18.3203, 207Pb/204Pb = 15.6458–15.6502, and 208Pb/204Pb = 38.6974–38.7271) plot between the orogenic-belt and upper-crustal evolution lines on tectonic discrimination diagrams as well as in the upper-crustal zone of a Δγ–Δβ genetic classification diagram, indicating that Pb within the Xiaban deposit was derived from a homogeneous upper-crustal source. Taken together, these mineralization and alteration, gangue and ore mineral assemblage, fluid inclusion, and H–O–S–Pb isotopic characteristics suggests that the Xiaban gold deposit is a low-sulfidation epithermal deposit. This result, together with the inferred minor amount of denudation that has affected the study area, means that the surrounding region should be considered prospective for this style of mineralization, with further exploration for epithermal mineralization within the Dehua goldfield ideally focusing on areas that show similar alteration characteristics to those found in the Xiaban deposit. [ABSTRACT FROM AUTHOR]