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The Dongyang gold deposit is a recently discovered large gold deposit located within the Dehua–Youxi–Yongtai mining camp in central–east Fujian Province, southeast China. The deposit contains two individual ore sections: the northwestern Jitou section and the southeastern Dadongkeng section. Most of the mineralization is hosted by rhyolite porphyry and volcanic rocks of the Nanyuan Formation. The locations of subvolcanic intrusions in this area are controlled by NE–SW and NW–SE trending faults that are also closely related to mineralization. Detailed drillhole logging and adit mapping indicates that the deposit contains massive, polymetallic quartz–sulfide veins, and cryptoexplosive breccia type ores. Ore minerals consist of gold, electrum, silver minerals, pyrite, marcasite, and arsenopyrite with lesser amounts of sphalerite and chalcopyrite. The mineralization is hosted by quartz, sericite, illite, chalcedony, and calcite gangue and is associated with sericite and argillic alteration as well as silicification. Fluid inclusion microthermometry indicates that the inclusions within quartz from auriferous quartz–sulfide veins formed during the main stage of mineralization and homogenize at temperatures (Th) of 172 °C–217 °C (average of 192 °C) and have salinities of 0.4–2.6 wt% NaCl equivalent. These low to moderate temperatures and low salinities suggest that the mineralization occurred in an epithermal environment. The precipitation of gold mineralization at Dongyang was most likely caused by the mixing of a large amount of meteoric fluid with a smaller amount of magmatic fluid. Quartz-hosted fluid inclusions have H and O isotope compositions (δDH2O = −63.1 to −54.2‰; δ18OH2O = −5.7‰ to −3.8‰) that are indicative of derivation from a predominantly meteoric source. The S isotope values of pyrite vary from a narrow range of −3.4‰ to 0.9‰, suggesting that the S within the deposit was derived from a homogeneous magmatic source. The mineralization and alteration, gangue and ore mineral assemblages, fluid inclusion and H–O–S isotope compositions indicate that the Dongyang gold deposit is a low-sulfidation epithermal-type deposit. The estimated ore formation depth of Donyang is nearly identical to its actual depth, indicating minor denudation in the region. These results imply a great prospecting potential for other epithermal mineralization at the Dehua–Youxi–Yongtai mining camp.

The Ancun gold deposit is located in the Dehua–Youxi–Yongtai ore region of Fujian Province, southeast China. The orebodies are mainly hosted in early Paleozoic quartz diorite and structurally controlled alteration zones along NW- and NE-trending faults. Based on the characteristics of mineralization, alteration mineral assemblages, fluid inclusions, and H–O–S isotope data, the Ancun gold deposit can be classified as an intermediate-sulfidation epithermal deposit. The primary metallic minerals are gold, electrum, pyrite, sphalerite, chalcopyrite, and galena, and the principal gangue minerals are quartz, calcite, sericite, and illite. The main types of wall rock alteration include sericitization, argillization, silicification, beresitization, and carbonation. Fluid inclusion studies were carried out on quartz and sphalerite from Au-bearing silicified massive ores and auriferous polymetallic-sulfide-bearing quartz veins from the main ore stage. Microthermometric measurements of fluid inclusions yielded homogenization temperatures (Th) of 152–255 °C and salinities of 0.9–5.3 wt% NaCl equivalent in quartz, and Th of 175–236 °C and salinities of 1.6–5.0 wt% NaCl equivalent in sphalerite. The low to moderate temperatures and salinities imply that the ore-forming fluids formed in epithermal environments. Gold deposition at Ancun is inferred to have been caused mainly by mixing of magmatic and diluted meteoric waters. The H and O isotopic compositions (δDH2O = −76.4‰ to −61.2‰; δ18OH2O = −6.1‰ to 4.0‰) of inclusion water in quartz imply that ore-forming fluids were derived mainly from magmatic sources. Sulfur isotopic values of sulfide minerals vary over a narrow range from −3.9‰ to −0.6‰, suggesting that S was derived from a homogeneous magmatic source. Based on the close temporal and spatial relationship between intermediate-sulfidation epithermal deposits and porphyry deposits, along with the alteration and mineralization characteristics of the Ancun gold deposit, potential exists in this region to drill into deeper-seated porphyry deposits.

The Wuhe area in eastern Anhui province, hosting 23 metric tons of gold, has been recognized as a new gold ore cluster in the North China Craton (NCC) since the Hekou gold deposit was discovered in 2017. Its metallogenic setting and ore-forming process remain unclear. In this contribution, we perform a combined geology, cathodoluminescence, fluid inclusion, H-O isotope and pyrite Rb-Sr geochronologic studies on the Hekou gold deposit of the Wuhe area. In order to perform detailed fluid inclusion petrography study, we used scanning electron microscope-cathodoluminescence (SEM-CL) on a well preserved sulfides-bearing quartz grain from the auriferous quartz vein. In this quartz grain, generation A barren quartz in the core zone (QA, CL-white), minor sulfides bearing generation B (QB, CL-light gray) in intermediate zone and sulfides rich generation C (QC, CL-dark gray) in the distal zone and fractures were revealed. Only in QC, the higher carbonic proportion (50–80 vol%) inclusions (CC) coexist with the two-phase liquid-rich aqueous fluid inclusions (LC) and sulfides, meanwhile the CC and the LC show a similar Th of 258–313 °C and 249–308 °C, but different salinities of 1.4–5.3 wt% NaCl equivalent and 6.0–10.9 wt% NaCl equivalent, respectively. It suggests that dominating fluid immiscibility recorded in QC is responsible for the prime deposition of gold and sulfide minerals. The δ18O (-4.1 to −6.5‰) and δD (-67.1 to −81.3‰) values of fluid inclusions in quartz suggest that ore-forming fluids were mainly derived from magmatic water which could related to mantle source. Gold-bearing pyrites yield an Rb-Sr isochron age of 128.1 ± 2.7 Ma, which is 8 m.y. earlier than the peak value of gold mineralization ages (ca. 120 Ma) at Jiaodong in response to the Early Cretaceous lithospheric thinning of the NCC and the reactivation of the Tan-Lu Fault zone (TLFZ). The Wuhe area shares similar characteristics of geology, fluid inclusions, H-O isotopes, and ore-forming ages with the Jiaodong gold ore cluster, highlighting the exploration potential in this region.

The Shuangqishan gold deposit is the largest gold deposit in the Dehua ore cluster of Fujian Province. The gold orebodies are located in the metamorphic rock of Neoproterozoic Daling Formation. Representative genetic models of Shuangqishan gold deposit include epithermal gold deposit, orogenic gold deposit and granitoid-related gold deposit. Based on the comprehensive research of pyrite Rb-Sr geochronology, telluride mineralogy and pyrite LA-ICP-MS trace element, we intend to discuss the genesis of the Shuangqishan gold deposit. The Rb-Sr isotopic dating of gold-bearing pyrite indicates that mineralization age of the Shuangqishan gold deposit is 153.5 ± 2.4 Ma, which is the same as that of the granite porphyry dyke (zircon U-Pb age = 153.4 ± 1.2 Ma) in the mining area. The main gold-bearing mineral is native gold, with a fineness of >920, additional gold-bearing mineral is electrum, with a fineness of 677 ~ 741. The gold-bearing polymetallic sulphide quartz veins contain a large amount of tellurbimuth (Bi2Te3), rucklidgeite (PbBi2Te4) and tetradymite (Bi2Te2S). The Shuangqishan gold deposit’s characteristic combination of Au-Bi-Te elements is analogous to that of typical magmatic-hydrothermal deposit. The estimated log f Te2 versus log f S2 conditions of telluride mineralization at 250 °C are –13.0 ~ –9.5, –14.7 ~ –10.5, respectively. LA-ICP-MS trace element analysis of gold-bearing pyrite shows that the pyrite is As-poor and has high content of Te, Bi, Pb, Co and Ni, but has low content of Au and As. The typical As-poor pyrite indicates that the Shuangqishan gold deposit is the magmatic hydrothermal gold deposit. Te displays a high positive correlation with Bi and Pb, indicating that Te, Bi and Pb occur as Bi-telluride micro-inclusion in pyrite. Our research shows that the Shuangqishan gold deposit is the magmatic hydrothermal gold deposit formed in the late Jurassic.

The Cathaysia Block is the southeastern part of the South China Block in Southeast (SE) China, and it hosts voluminous late Mesozoic I-, S-, and A-type granitoids, as well as minor highly fractionated granites. We present here zircon U–Pb age data and Nd–Hf isotopic data for the Dayang and Juzhou granites, together with new petrological and geochemical analyses. The Dayang pluton consists of fine-grained two-mica monzonitic granites in which the plagioclases exhibit zoning and poikilitic textures. In contrast, the Juzhou pluton consists of medium- to coarse-grained biotite K-feldspar granites that lack zoning and poikilitic textures. The emplacement ages are 143 ± 2.3 Ma for the Dayang pluton and 133 ± 2.1 Ma for the Juzhou pluton according to zircon U–Pb isotope analyses. The Dayang and Juzhou granites are both metaluminous and belong to the shoshonitic series. The Dayang granite exhibits very flat REE patterns, showing the tetrad effect, and the spidergrams show striking negative Ba, Sr, Nb, and Ti anomalies and a positive Ta anomaly. In contrast, the Juzhou granite has sloping REE patterns, but like the Dayang granite it also has striking negative Ba, Sr, Nb, Ta, and Ti anomalies. Petrographic and geochemical evidence indicates that the Dayang granite is a highly fractionated I-type granite and that the Juzhou granite is a typical I-type granite. The tetrad effect in the Dayang granite can be interpreted in terms of melt–rock interactions at a late stage of magma evolution, whereas the main mechanism during the evolution of the Juzhou magma was fractionation of plagioclase, biotite, hornblende, apatite, zircon, and allanite. Nd–Hf isotope data suggest that the Dayang and Juzhou granites were both formed partial melting of Paleoproterozoic basement rock and juvenile material (underplating basalts or Mayuan Group amphibolites), with the Juzhou granite having a greater contribution from juvenile material than the Dayang granite. Our new data, together with existing data, suggest that the tectonic setting of the early Yanshanian (∼143 Ma) highly fractionated I-type Dayang granite was a back-arc that formed in response to the westward subduction of the Paleo-Pacific Plate, and that the late Yanshanian (∼133 Ma) Juzhou granite formed in a continental arc setting in response to rollback of the Paleo-Pacific Plate toward the coastline. The Mo mineralization in the Makeng ore area was probably the result of the exsolution of Mo-bearing fluids from the Dayang granitic magmas due to extensive fractional crystallization.

The large-scale Maoping W&ndash, Sn deposit in the Gannan metallogenic belt of the eastern Nanling Range, South China, spatially associated with the Maoping granite pluton, hosts total ore reserves of 103,000 t WO3 and 50,000 t Sn. Two different types of mineralization developed in this deposit: Upper quartz vein-type mineralization, mostly within the Cambrian metamorphosed sandstone and slate, and underneath greisen-type mineralization within the Maoping granite. Cassiterites from both types of mineralization coexist with wolframite. Here we report for the first time in situ U&ndash, Pb data on cassiterite and zircon of the Maoping deposit obtained by LA-ICP-MS. Cassiterite from quartz vein and greisen yielded weighted average 206Pb/238U ages of 156.8 &plusmn, 1.5 Ma and 156.9 &plusmn, 1.4 Ma, respectively, which indicates that the two types of mineralization formed roughly at the same time. In addition, the two mineralization ages are consistent with the emplacement age of the Maoping granite (159.0 &plusmn, 1.5 Ma) within error, suggesting a close temporal and genetic link between W&ndash, Sn mineralization and granitic magmatism. The two types of mineralization formed at the same magmatic-hydrothermal event. Cassiterite from both types of mineralization shows high Fe, Ta, and Zr contents with a low Zr/Hf ratio, suggesting that the ore-forming fluid should be derived from the highly differentiated Maoping granite pluton. Cassiterite in greisen has higher contents of Nb and Ta but a lower concentration of Ti compared with that in quartz vein, indicating that the formation temperature of greisen-type mineralization is little higher than that of quartz-vein-type mineralization.

The Xianhualing District at Jinzhai in the northern Dabie Orogen, China, is a significant area for Pb–Zn–Cu–Au polymetallic exploration. The main rocks in the area are mica–quartz schist of the Neoproterozoic Foziling Group, and magmatic rocks which are controlled by two sets of faults striking NNE and NW. Recent drilling has revealed that the orebody occurs mainly in mica–quartz schist in the form of breccia and veinlets. Major ore minerals include pyrite, sphalerite, galena, chalcopyrite, magnetite, gold, silver, and silver sulfosalts, with alteration assemblages of predominantly quartz, sericite, calcite, and chlorite. Three types of fluid inclusions occur in quartz–sulfide vein samples collected from eight drill-holes: two-phase liquid-rich inclusions (type I), two-phase vapor-rich inclusions (type Ⅱ), and halite-bearing inclusions (type III). Microthermometric studies of type I and Ⅱ fluid inclusions indicate homogenization temperatures of 161–378 °C and salinities of 0.5–7.8 wt% NaCl equivalent. Fluid inclusion microthermometric data and mineralization and alteration characteristics indicate an intermediate-sulfidation epithermal environment. Current exploration is focused on the location of potential deep porphyry mineralization associated with epithermal mineralization. In this study, 28 drill-core samples from different levels were selected for fluid inclusion microthermometry to elucidate fluid-evolution pathways and hence to determine the likelihood of porphyry bodies. The consistent fluid inclusion petrography, distribution patterns, and fluid-evolution trends indicate that the deeper part of the Dongchong area may have been the regional thermal center of fluid flow. The estimated mineralization depths of type III fluid inclusions are in the range 0.4–1.5 km, indicating a relatively shallow formation. Fluid chemical compositions obtained from single-inclusion laser-ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) analyses support the occurrence of a single magmatic–hydrothermal fluid source, which has a degree of mixing with meteoric water and a small amount of basinal brines during the migration path, and the fluid evolution pattern agrees well with the fluid inclusion mapping result. Quartz-vein hosted fluid inclusions contain significant amounts of Pb, Zn, and Cu, indicating good exploration prospects for porphyry Cu mineralization at depth.

The Shuangqishan Au deposit lies in the Dehua–Youxi–Yongtai Au metallogenic belt in central eastern Fujian Province, SE China. The orebodies are hosted mainly in the Neoproterozoic Dalingyan Formation. Based on the characteristics of mineralization, alteration mineral assemblages, fluid inclusions, and H–O–C–S–Pb isotopic data, the deposit is classified as a granitoid-related deposit. The primary metallic minerals are native gold, electrum, pyrite, chalcopyrite, galena, tellurbimuth, and tetradymite; the main gangue minerals are quartz, calcite, sericite, and illite. The main types of wall-rock alteration are silicification, pyritization, carbonatization, and sericitization. Fluid inclusions in quartz from auriferous polymetallic sulfide-bearing quartz veins from the main ore stage were studied. Two-phase liquid-rich (type I), CO2-rich (type II), and pure CO2 (type III) inclusions were identified. Their homogenization temperatures (196 °C–295 °C) and salinities (0.8–5.0 wt% NaCl equivalent) indicate that the ore-forming fluids of the Shuangqishan deposit were of a medium-temperature, low-salinity H2O–CO2–NaCl system. Gold deposition at Shuangqishan was likely caused by immiscibility of fluids. H isotopic compositions (δDH2O = −68.0‰ to −64.8‰) of inclusion water in quartz and O isotopic compositions (δ18OH2O = 3.8‰ to 6.3‰) of fiuid, which was calculated from δ18O of quartz, imply that ore-forming fluids were mainly of magmatic origin. C isotopic compositions (δ18CPDB = −15.7‰ to −5.7‰) of the fluid inclusions indicate that the CO2 in the ore-forming fluids was predominantly magma-derived, but was contaminated by organic carbon from the Neoproterozoic Dalingyan Formation. δ34S values of sulfide minerals have a narrow range of–2.7‰ to −0.9‰, suggesting that S was derived from a homogeneous magmatic source. Pb isotopic ratios of gold-bearing ores are similar to those of late Mesozoic granodiorite porphyry of the Xianyang pluton, indicating that the granodiorite porphyry was the source of Pb for the ores.

The Xiaoqinling district, the second largest gold producing district in China, is located on the southern margin of the North China Craton. It consists of three ore belts, namely, the northern ore belt, the middle ore belt and the southern ore belt. Pyrite from the Dahu gold deposit in the northern ore belt and Wenyu and Yinxin gold deposits in the southern ore belt were investigated using a combination of ore microscopy and in-situ laser-ablation inductively-coupled plasma-mass spectrometry (LA-ICP-MS). A range of trace elements was analyzed, including Au, Te, Ag, Pb, Bi, Cu, Co, Ni, Zn, Mo, Hg, As and Si. The results show that there are no systematic differences between the trace element compositions of pyrite in the three deposits from different ore belts. In general, Au concentrations in pyrite are low (from 2 -rich ore fluids; spatial association with large-scale compressional structures of the Qinling orogen; δ 18 O and δD data suggestive of mixing between metamorphic and meteoric waters; δ 34 S and Pb-isotopic data that point to a mixed crustal-mantle source) all point to typical orogenic-type gold deposits. High Ni concentrations (up to 8425 ppm) of pyrite possibly linked to deep-seated mafic/ultramafic metamorphic rocks provide further evidence on the orogenic gold deposit affinity, but against the model of a granitic derivation of the mineralizing fluid as previously suggested by some workers. Generally low Au concentration in pyrite is also consistent with those from worldwide orogenic gold deposits. Therefore, the gold mineralization in the Xiaoqinling district is described as orogenic type, and is probably related to Indosinian collision between the North China Craton and the Yangtze Craton.

The Yulong porphyry copper ore belt is the largest belt of porphyry copper deposits in China. Detailed geological and geochemical comparison indicates that ore-bearing and barren porphyries in this belt were derived by progressive partial melting of veins of phlogopite-garnet clinopyroxenite in lherzolitic lithosphere. Ore-bearing porphyry represents the earliest melt derived by partial melting of accessory phases such as apatite, carbonate, and phlogopite, and thus contains high contents of volatiles F, Cl, and H2O. These volatiles promoted copper extraction and enrichment. Barren porphyry is the product of relatively high degrees of partial melting involving clinopyroxene and garnet, and thus is depleted in volatiles, hence barren of copper. This is the essential petrogenetic discrimination between ore-bearing and barren porphyries. Geochemical discrimination includes the following: Cu > 100 ppm, W > 5 ppm, F + Cl > 900 ppm, K2O/Na2O > 1.2, and Sm/Yb > 6.5 for bulk rock of the ore-bearing porphyries, an...