Search Results (49)

The Shabaosi gold field is located in the western Mohe Basin, part of the northern Great Xing’an Range, NE China, and contains multiple gold deposits. However, the sources of the ore-forming materials, the fluid evolution, and the genesis of these gold deposits have been disputed, especially regarding the classification of these deposits as either epithermal or orogenic gold systems. Based on detailed field geological investigations and previous research, we conducted systematic research on the Shabaosi, Sanshierzhan, Laogou, and Balifang gold deposits using fluid inclusion and H-O-S-Pb isotope data, with the aim of constraining the fluid properties, sources, and mineralization processes. Fluid inclusion analyses reveal diverse types, including vapor-rich, vapor–liquid, CO₂-bearing, CO₂-rich, and pure CO₂. Additionally, only a very limited number of daughter mineral-bearing fluid inclusions have been observed exclusively in the Laogou gold deposit. During the early stages, the peak temperature primarily ranged from 240 °C to 280 °C, with salinity concentrations between 6 and 8 wt% NaCl equiv., representing a medium–low temperature, low salinity, and a heterogeneous CO₂-CH₄-H₂O-NaCl system. With the influx of meteoric water, the fluids evolved gradually into a simple NaCl-H₂O system with low temperatures (160–200 °C) and salinities (4–6 wt%). The main mineralization stage exhibited peak temperatures of 220–260 °C and salinities of 5–8 wt% NaCl equiv., corresponding to an estimated formation depth of 1.4–3.3 km. The δD_V-SMOW values (−138.3‰ to −97.0‰) and δ¹⁸O_V-SMOW values (−7.1‰ to 16.2‰) indicate that the magmatic–hydrothermal fluids were progressively diluted by meteoric water during mineralization. The sulfur isotopic compositions (δ³⁴S = −0.9‰ to 1.8‰) and lead isotopic ratios (²⁰⁸Pb/²⁰⁴Pb = 38.398–38.579, ²⁰⁷Pb/²⁰⁴Pb = 15.571–15.636, and ²⁰⁶Pb/²⁰⁴Pb = 18.386–18.477) demonstrate that the gold predominantly originated from deep magmatic systems, with potential crustal contamination. Comparative analyses indicate that the Shabaosi gold field should be classified as a epizonal orogenic gold system, which shows distinct differences from epithermal gold deposits and corresponds to the extensional tectonic setting during the late-stage evolution of the Mongol–Okhotsk orogenic belt. Full article

This study critically examines the early Cretaceous carbonate-hosted Zn-Pb (±Ba±Cu) deposits of the Malayer-Esfahan (MEMB) and Yazd-Anarak (YAMB) metallogenic belts in Iran, which have been inaccurately classified as Mississippi Valley type (MVT) deposits by Nejadhadad et al. (2025). Our findings reveal significant differences in mineralogy, fluid inclusion characteristics, and geochemical signatures compared to typical MVT deposits. These deposits are more akin to Irish-type Zn-Pb mineralization and formed in extensional and passive margin environments around the Nain–Baft back-arc basin. The normal faults in this back-arc rift can transform significantly during inversion and compressional tectonics, reactivating to behave as reverse faults and leading to new geological structures and landscapes. Our study highlights barite replacement as a crucial factor in forming sediment-hosted Zn-Pb (±Ba±Cu) and barite-sulfide deposits. Based on textural evidence, fluid inclusion data, and sulfur isotope analyses, we propose that barite plays a fundamental role in controlling subsequent Zn-Pb (±Ba±Cu) mineralization by serving as both a favorable host and a significant sulfur source. Furthermore, diagenetic barite may act as a precursor to diverse types of sediment-hosted Zn-Pb (±Ba±Cu) mineralization, refining genetic models for these deposits. Sulfur isotope analyses of Irish-type deposits show a broad δ³⁴S range (−28‰ to +5‰), indicative of bacterial sulfate reduction (BSR). Nevertheless, more positive δ³⁴S values (+1‰ to +36‰) and textural evidence in shale-hosted massive sulfide (SHMS) deposits suggest a greater role for thermochemical sulfate reduction (TSR) in sulfide mineralization. Full article

A combination of microstructural, fluid inclusion, and in situ sulfur isotopic analyses of pyrite, along with major and trace element studies of the mineralization-hosting sandstone, reveals the complexity of its genesis from the Jurassic Toutunhe Formation in the Liuhuanggou sandstone-hosted uranium deposit, Southern Junggar Basin. Based on field geological investigations and the geochemical characteristics, it is concluded that the source of the ore-bearing sandstones originates from felsic igneous rocks in the Northern Tianshan and Central Tianshan regions. Through optical microscopy and scanning electron microscopy (SEM), three generations of pyrite were identified: framboidal pyrite, concentric overgrown pyrite, and sub-idiomorphic to idiomorphic cement pyrite. The sulfur isotopes of the pyrite were analyzed using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). The results indicate that each type of pyrite has distinct sulfur isotope compositions (the framboidal pyrite: −16.85‰ to +2.16‰, the concentric overgrown pyrite: −7.86‰ to +10.32‰, the sub-idiomorphic to idiomorphic cement pyrite: +9.16‰ to +16.77‰). The framboidal pyrite and the sub-idiomorphic to idiomorphic cement pyrite were formed through bacterial sulfate reduction (BSR), while the concentric overgrown pyrite was formed through thermochemical sulfate reduction (TSR) triggered by the upward migration of hydrocarbons. The discovery of hydrocarbon inclusions provides evidence for the involvement of deep-seated reducing fluids in uranium mineralization. Uranium mineralization occurred in two distinct stages: (1) The early stage involved the interaction of uranium-bearing fluids with reductants in the mineralization-hosting strata under the influence of groundwater dynamics, leading to initial uranium enrichment. (2) The later stage involved the upward migration of deep-seated hydrocarbons along faults, which enhanced the reducing capacity of the sandstone and resulted in further uranium enrichment and mineralization. Full article

The Axi gold deposit, which is located in the Tulasu Basin of the West Tianshan orogenic belt in Northwest China, features vein-type ore bodies hosted in radial structural fractures formed due to volcanic activity. The deposit experienced three distinct mineralization stages: Stage I, characterized by the microcrystalline quartz–pyrite crust; Stage II, characterized by quartz–sulfide–native gold veins; and Stage III, characterized by quartz–carbonate veins. Fluid inclusion studies have identified four types of inclusions: pure vapor, vapor-rich, liquid-rich, and pure liquid. The number of vapor-rich inclusions decreases when moving from Stage I to Stage III, whereas the number of liquid-rich inclusions increases. The fluid temperature gradually decreases from 178–225 °C in Stage I to 151–193 °C in Stage II and further to 123–161 °C in Stage III, whereas the fluid salinity decreases slightly from 2.1%–5.1% wt.% NaCl eqv to 1.4%–4.6% wt.% NaCl eqv and finally to 0.5%–3.7% wt.% NaCl eqv. As suggested by the results of the oxygen, hydrogen, and carbon isotope analyses, the ore-forming fluids were primarily meteoric water. Sulfur isotopic compositions indicate a single deep mantle source. The lead isotopic compositions closely resemble those of Dahalajunshan Formation volcanic rocks, indicating that these rocks were the primary source of the ore-forming material. In addition, gold mineralization formed in a Devonian–Early Carboniferous volcanic arc environment. Element enrichment was mainly caused by the circulation of heated meteoric water through the volcanic strata, while fluid boiling and water–rock interactions were the main mechanisms driving element precipitation. The integrated model developed in this study underscores the intricate interplay between volcanic processes and meteoric fluids during the formation of the Axi gold deposit, offering a robust framework for an understanding of the formation processes and enhancing the predictive exploration models in analogous geological settings. Full article

The Jiepailing deposit in southern Hunan is a typical large to super-large polymetallic tin deposit enriched in beryllium and other rare metals. To enhance the understanding of the mineralization processes of the Jiepailing deposit, detailed mineralogical, in situ geochemical, and sulfur isotopic analyses were conducted on pyrite closely associated with tin–polymetallic mineralization. Five types of pyrite have been identified in the deposit: (1) euhedral to subhedral medium- to coarse-grained pyrite (PyI) in tungsten–tin ore; anhedral fine-grained pyrite (PyII) in tin polymetallic–fluorite ore; anhedral fine-grained or aggregate pyrite (PyIII) in lead–zinc ore; euhedral to subhedral coarse-grained pyrite (PyIV) in beryllium–fluorite mineralization; and subhedral to anhedral fine-grained pyrite (PyV) in carbonate veinlets developed in the wall rock. Backscattered electron imaging indicates consistent structural features across the five types of pyrite. In situ trace element analysis reveals differences in trace element concentrations among the pyrite types. PyI is relatively enriched in Sn, Cu, and Co. In contrast, PyIII is enriched in Pb, Zn, Sn, and Ti, while PyIV and PyV are enriched in Ag and Sb. PyI has a Co/Ni ratio more than 1, while the Co/Ni ratios in the other four types of pyrite are less than 1. LA-MC-ICP-MS in situ sulfur isotope analysis shows δ³⁴S values ranging from 2.5‰ to 5.8‰ (average 4.3‰, PyI), 2.5‰ to 5.8‰ (average 4.3‰, PyII), −7.6‰ to 9.5‰ (average 3.9‰, PyIII), −3.7‰ to 10.6‰ (average 3.6‰, PyIV), and 6.8‰ to 14.1‰ (average 9.2‰, PyV). Based on previous studies, regional geological background, deposit characteristics, and the in situ trace element and sulfur isotope compositions of pyrite, it is inferred that the various ore bodies in the Jiepailing deposit are products of Late Cretaceous magmatic–hydrothermal activity. The early ore-forming fluid originated from magmatic sources and during the migration into the wall rock and shallow formations, mixed with fluids primarily derived from atmospheric precipitation. Temperature, pressure, and composition changed of the ore-forming fluid which carried a large amount of substances, leading to tungsten–tin, tin polymetallic–fluorite, lead–zinc, and beryllium–fluorite mineralization, followed by carbonation during the late-stage mineralization. Full article

The sulfide Pb–Zn deposits in the Aksai Chin region of Xinjiang have long been subject to debate regarding their genetic classification due to the unclear origin of the ore-forming components. This study focuses on the Sachakou Pb–Zn deposit, the most representative deposit in the region, and integrates field investigations, petrographic observations, in situ LA-ICP-MS trace element analysis, and in situ S–Pb isotope analysis. The deposit is hosted within the siliceous rock and silicified limestone of the Lower Jurassic Bagongbulansha Formation, with ore bodies controlled by structural and stratigraphic factors. Three mineralization stages have been identified in the Sachakou deposit: a red–brown sphalerite mineralization stage (S1), a light-brown sphalerite stage (S2), and a galena mineralization stage (S3). The trace elements in sphalerite indicate that the mineralization process is unrelated to magmatic activity. The mineralization temperature, determined using a GGIMFis geothermometer, ranges from 294 °C to 121 °C. The δ³⁴S_V-CDT values of sulfides range from −4.93‰ to 1.24‰, suggesting that the Jurassic gypsum layer served as the sulfur source. The lead isotope ratios of ²⁰⁶Pb/²⁰⁴Pb range from 18.308 to 18.395, of ²⁰⁷Pb/²⁰⁴Pb—from 15.669 to 15.731, and of ²⁰⁸Pb/²⁰⁴Pb—from 38.595 to 38.776, indicating that the ore-forming metals were predominantly sourced from the upper crust. Based on geological and geochemical characteristics, the Sachakou Pb–Zn deposit is classified as a sedimentary-hosted epizonogenic hydrothermal deposit. Full article

The Biggenden gold-bearing Fe skarn deposit in southeast Queensland, Australia, is a calcic magnetite skarn that has been mined for Fe and gold (from the upper portion of the deposit). Skarn has replaced volcanic and sedimentary rocks of the Early Permian Gympie Group, which formed in different tectonic settings, including island arc, back arc, and mid-ocean ridge. This group has experienced a hornblende-hornfels grade of contact metamorphism due to the intrusion of the Late Triassic Degilbo Granite. The intrusion is a mildly oxidized I-type monzogranite that has geochemical characteristics intermediate between those of granitoids typically associated with Fe-Cu-Au and Sn-W-Mo skarn deposits. The skarn mineralogy indicates that there was an evolution from prograde to various retrograde assemblages. Prograde garnet (Adr_11-99Grs_1-78Alm_0-8Sps_0-11), clinopyroxene (Di_30-92Hd_7-65Jo_0-9), magnetite, and scapolite formed initially. Epidote and Cl-bearing amphibole (mainly ferropargasite) were the early retrograde minerals, followed by chlorite, calcite, actinolite, quartz, and sulfides. Late-stage retrograde reactions are indicated by the development of nontronite, calcite, and quartz. Gold is mainly associated with sulfide minerals in the retrograde sulfide stage. The fluids in equilibrium with the ore-stage calcites had δ¹³C and δ¹⁸O values that indicate deposition from magmatically derived fluids. The calculated δ¹⁸O values of the fluids in equilibrium with the skarn magnetite also suggest a magmatic origin. However, the fluids in equilibrium with epidote were a mixture of magmatic and meteoric water, and the fluids that deposited chlorite were at least partly meteoric. δD values for the retrograde amphibole and epidote fall within the common range for magmatic water. Late-stage chlorite was deposited from metasomatic fluids depleted in deuterium (D), implying a meteoric water origin. Sulfur isotopic compositions of the Biggenden sulfides are similar to other skarn deposits worldwide and indicate that sulfur was most probably derived from a magmatic source. Based on the strontium (⁸⁷Sr/⁸⁶Sr) and lead (²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb) isotope ratios, the volcanic and sedimentary rocks of the Gympie Group may have contributed part of the metals to the hydrothermal fluids. Lead isotope data are also consistent with a close age relationship between the mineralization at Biggenden and the crystallization of the Degilbo Granite. Microthermometric analysis indicates that there is an overall decrease in fluid temperature and salinity from the prograde skarn to retrograde alterations. Fluid inclusions in prograde skarn calcite and garnet yield homogenization temperatures of 500 to 600 °C and have salinities up to 45 equivalent wt % NaCl. Fluid inclusions in quartz and calcite from the retrograde sulfide-stage homogenized between 280 and 360 °C and have lower salinities (5–15 equivalent wt % NaCl). In a favored genetic model, hydrothermal fluids originated from the Degilbo Granite at depth and migrated through the shear zone, intrusive contact, and permeable Gympie Group rocks and leached extra Fe and Ca and deposited magnetite upon reaction with the adjacent marble and basalt. Full article

The large-scale vein-type Zn-Pb-Ag deposit in the Eastern Qinling Orogen (EQO) has sparked a long-standing debate over whether magmatism or metamorphism was the primary control or factor in its formation. Among the region’s vein-type deposits, the large-sized Bailugou deposit offers a unique opportunity to study this style of mineralization. Similar to other deposits in the area, the vein-type orebodies of the Bailugou deposit are hosted in dolomitic marbles (carbonate–shale–chert association, CSC) of the Mesoproterozoic Guandaokou Group. Faults control the distribution of the Bailugou deposit but do not show apparent spatial links to the regional Yanshanian granitic porphyry. This study conducted comprehensive H–O–C–S–Pb isotopic analyses to constrain the sources of the ore-forming metals and metal endowments of the Bailugou deposit. The δ³⁴S_CDT values of sulfides range from 1.1‰ to 9.1‰ with an average of 4.0‰, indicating that the sulfur generated from homogenization during the high-temperature source acted on host sediments. The Pb isotopic compositions obtained from 31 sulfide samples reveal that the lead originated from the host sediments rather than from the Mesozoic granitic intrusions. The results indicate that the metals for the Bailugou deposit were jointly sourced from host sediments of the Mid-Late Proterozoic Meiyaogou Fm. and the Nannihu Fm. of the Luanchuan Group and Guandaokou Group, as well as lower crust and mantle materials. The isotopic composition of carbon, hydrogen, and oxygen collectively indicate that the metallogenic constituents of the Bailugou deposit were contributed by ore-bearing surrounding rocks, lower crust, and mantle materials. In summary, the study presents a composite geologic-metallogenic model suggesting that the Bailugou mineral system, along with other lead-zinc-silver deposits, porphyry-skarn molybdenum-tungsten deposits, and the small granitic intrusions in the Luanchuan area, are all products of contemporaneous hydrothermal diagenetic mineralization. This mineralization event transpired during a continental collision regime between the Yangtze and the North China Block (including syn- to post-collisional settings), particularly during the transition from collisional compression to extension around 140 Ma. The Bailugou lead-zinc-silver mineralization resembles an orogenic-type deposit formed by metamorphic fluid during the Yanshanian Orogeny. Full article

The Xinjiazui gold deposit marks a notable significance in prospecting within the Back-Longmenshan tectonic belt, located on the northwest margin of the Yangtze Block, China. Despite the extensive studies conducted on this deposit, the source of the ore-forming materials remains unclear, leading to ongoing debates regarding the genesis of this deposit. This study analyzed in situ (EPMA and LA-ICP-MS) trace elements and S-Pb isotopes of arsenopyrite, solely from the principal metallogenic stage and paragenetic with native gold. The results show that the gold in arsenopyrite occurs as invisible gold (Au³⁺), with an average concentration of 9.38 ppm, whereas the concentrations of magma-related elements, such as W, Sn, Mo, and Bi, are very low. The sulfur isotopes (³⁴S) of arsenopyrite range from 8.32‰ to 10.16‰, aligning closely with the deep metamorphic basement (Pt₃l). Meanwhile, the lead isotopes in arsenopyrite display characteristics typical of those found in orogenic belts. A comprehensive analysis of the abundance of gold indicated that the metallogenic materials (sulfur and gold) primarily originated from Pt₃l. Additionally, the arsenopyrite thermobarometer indicated that the Xinjiazui gold deposit formed in a medium–low-temperature, medium metallogenic environment (5.57–8.69 km), with a sulfur fugacity (log f (S₂)) below −8.4. Combined with previous research results, this study proposes that the Xinjiazui gold deposit is a subduction-related mesozonal orogenic gold deposit. In gold prospecting and exploration in the Back-Longmenshan tectonic belt, it is essential to focus on the distribution of brittle-ductile shear zones and location of the quartz veins associated with pyrite and arsenopyrite mineralization. Full article

The coexistence of numerous Mississippi-Valley-type (MVT) Zn–Pb deposits and (paleo) oil/gas reservoirs in the world suggests a close genetic relationship between mineralization and hydrocarbon accumulation. Xuequ–Shandouya middle MVT Zn–Pb deposits are mainly hosted in the Lower Cambrian Maidiping Member siliceous dolostone on the southwestern margin of the Yangtze Block, accompanied by large amount of bitumen in the orebodies. Therefore, this type of Zn–Pb deposit is a natural laboratory for studying the relationship between the mineralization and the accumulation of paleo-oil/gas reservoirs. The deposit is characterized by spheroidal and concentric banded sphalerite. In situ sulfur isotope studies are carried out to determine the sulfur sources, sulfate reduction mechanisms, and role of hydrocarbons in the zinc–lead mineralization process. According to the mineral paragenesis and relative temporal relationship, two mineralization stages (1 and 2) are identified. An in situ sulfur isotope analysis of spheroidal and concentric banded sphalerite particles from Stage 2 shows that there are the two following types of sulfur isotopes in the sphalerite: one with relatively invariable δ³⁴S values in the core (+8.31 to +9.30‰), and the other with a gradual increase from the core margin (core) to the rim (+0.39 to +16.18‰). These two types reflect that they may have formed in different times, with first type forming in the early period of Stage 2, while the second type was formed in the late period of Stage 2. The sulfur isotopic data suggest the sulfur source of evaporated sulfate minerals and multiple formation mechanisms for reduced sulfur (H₂S). In the early period of Stage 2 mineralization, the sulfate reduction mechanism is mainly a mixture of bacterial sulfate reduction (BSR) and/or thermochemical sulfate reduction (TSR), while a very small amount may come from the thermal decomposition of organic compounds (DOCs). In the late period of Stage 2, TSR is dominant, and the gradual increase in the δ³⁴S value may be related to Rayleigh fractionation. The oil/gasreservoir not only acts as a reducing agent to provide the required hydrogen sulfide for zinc–lead mineralization through TSR or BSR, but also provides reduced sulfur for mineralization through the thermal decomposition of organic compounds directly. Full article

Objectives: The metabolic pathway of cancerous tissue differs from healthy tissue, leading to the unique isotopic composition of stable isotopes at their natural abundance. We have studied if these changes can be developed into diagnostic or prognostic tools in the case of endometrial cancer. Methods: Measurements of stable isotope ratios were performed using isotope ratio mass spectrometry for nitrogen, carbon, and sulfur isotopic assessment. Uterine tissue and serum samples were collected from patients and the control group. Results: At a natural abundance, the isotopic compositions of all three of the studied elements of uterus cancerous and healthy tissues are different. However, no correlation of the isotopic composition of the tissues with that of serum was found. Conclusions: Differences in the isotopic composition of the tissues might be a potential prognostic tool. However, the lack of a correlation between the differences in the isotopic composition of the tissues and serum seems to exclude their application as diagnostic biomarkers, which, however, might be possible if a position-specific isotopic analysis is performed. Full article

The release of pollutants from lead-zinc mining areas poses a significant threat to the environment, making pollution tracing crucial for environmental protection. However, the complexity of carbonate mining areas makes tracing these pollutants challenging. This study used δ³⁴S_SO4 and δ¹⁸O_SO4 isotopes combined with the Stable Isotope Mixing Models in R (SIMMR) to assess anthropogenic sulfate sources in the Daliangzi mining area. The river water types were mainly Ca²⁺-Mg²⁺-HCO₃⁻, and SO₄²⁻, which are significantly influenced by dolomite dissolution. The δ³⁴S_SO4 values ranged from 6.47‰ to 17.96‰ and the δ¹⁸O_SO4 values ranged from −5.66‰ to 13.98‰. The SIMMR results showed that evaporite dissolution in tributaries, driven by gypsum, contributed 31% of sulfate, while sulfide oxidation, sewage, and atmospheric deposition contributed 19%, 18%, and 24%, respectively. The tailings pond near Xincha Creek has a higher sulfate release potential than the processing plant near Cha Creek. In the mainstream, sulfide oxidation contributed 25%, primarily from mine drainage. Anthropogenic sources, including sulfide oxidation, fertilizers, and sewage, made up about 50% of the total sulfate, with sulfide oxidation accounting for half of this input. The strong correlation between the Zn and SO₄²⁻ concentrations (R² = 0.82) and between the Zn and the contribution from the sulfide oxidation (R² = 0.67) indicates their co-release during sulfide oxidation, making SO₄²⁻ a proxy for tracing Zn sources. This study highlights the utility of δ³⁴S_SO4 and δ¹⁸O_SO4 with SIMMR in tracing anthropogenic inputs and underscores the significant impact of mining on river systems and the sulfur cycle. Full article

The northern margin of the North China Craton is one of the most important porphyry-skarn molybdenum ore belts in the world. The eastern Hebei Province, which contains a high number of molybdenum and gold (molybdenum) resources, is an important portion of the northern margin of the North China Craton. Xichanggou and Huashi, located in eastern Hebei, are quartz-molybdenum vein deposits that are intimately associated with intrusions that are deeply concealed in the mining area. This work presents two zircon U-Pb dates and ten molybdenite Re-Os ages from samples of the aforementioned two deposits in order to determine the timing of the intrusion and mineralization. The zircon U-Pb ages of the quartz monzonite porphyry from Xichanggou are determined to be 163.3 ± 0.3 Ma and 162.8 ± 0.4 Ma. The molybdenite Re-Os dating yielded ages of 160.3 ± 4.6 Ma for Xichanggou and 171.4 ± 19 Ma for Huashi, respectively. The isotopic composition of oxygen and hydrogen of the ore-forming fluid from Huashi, as indicated by the δD_V-SMOW values (−80.0‰ to −67.6‰) and δ¹⁸O_H2O values (−1.86‰ to 2.33‰), suggests that the fluid is primarily composed of water derived from magma, with some contribution from atmospheric precipitation. The sulfur isotope values (δ³⁴S) of sulfides from Xichanggou range from 6.5‰ to 7.1‰, while the δ³⁴S values from Huashi range from 3.3‰ to 4.9‰. The lead isotope ratios (²⁰⁶Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb) of sulfides from Xichanggou and Huashi average at 17.414, 15.428, and 17.591, 15.379, respectively. The Re-Os isotopic compositions of ore sulfides mostly fall within the range of 318 ppm to 50,114 ppm. These isotopic compositions indicate that the materials responsible for the formation of the ores in Xichanggou and Huashi primarily originate from the melting of lower crust materials that have been contaminated by the mantle. Based on the regional data, the molybdenum deposits in eastern Hebei were formed in multiple periods, specifically approximately 170 Ma and 160 Ma in Huahsi and Xichanggou, respectively. The subduction of the Paleo-Pacific plate during the middle–late Jurassic period led to the partial remelting of lower crust material, resulting in the acquisition of a significant quantity of metal elements (Mo), which were subsequently deposited. Full article

The Fang’an gold deposit in the Wuhe area, Anhui Province, is located in the area adjacent to the Bengbu Uplift and Wuhe Platform Depression in the southeastern part of North China. This study aimed to determine the deposit’s mineralization age and the source of its metallogenic materials and mineralization processes through investigations into its geological characteristics, Rb–Sr isotopes, and S–Pb isotopes. The orebodies of the Fang’an gold deposit in the Neoarchean Xigudui Formation primarily exhibit a vein-type structure. The ore-forming process can be divided into four stages: (i) the quartz stage (Py1); (ii) the quartz–pyrite stage (Py2); (iii) the polymetallic sulfide stage (Py3); and (iv) the carbonate stage. Of these, the main mineralization stage is also the main period in which gold mineralization occurs. In situ sulfur isotope results of pyrite (Py1 to Py3) in the first three mineralization stages, suggesting a contribution of sulfur from crust–mantle magmatic fluids. The δ³⁴S values for Py2 (average 5.51‰) are higher than Py1 (average 4.45‰) and showed that the magmatic fluids mixed with meteoric waters. The δ³⁴S values for Py3 (average 5.18‰) are lower than Py2 (average 5.51‰), revealing that it related fluid immiscibility. The lead isotopic compositions of sulfides within the ores possessed ²⁰⁶Pb/²⁰⁴Pb ratios ranging from 16.759 to 16.93, ²⁰⁷Pb/²⁰⁴Pb ratios ranging from 15.311 to 15.402, and ²⁰⁸Pb/²⁰⁴Pb ratios ranging from 37.158 to 37.548. These lead data were plotted close to the Xigudui Formation, relatively distant from the Mesozoic granites, indicating that the Xigudui Formation was the source of lead for the Late Mesozoic ores of the deposit. Taken together, due to the degassing of mantle-derived magma in the shallow parts of the crust, it can be determined that the sources of ore-forming sulfur and lead were crust–mantle magmatic activities in the Wuhe area. Rb–Sr dating of pyrite from Fang’an gold deposit reveals that the mineralization occurred at 126.89 ± 0.58 Ma. Considering the previous research into the dating of magmatic rocks in the Wuhe area, we propose that the genesis of the Fang’an gold deposit is closely associated with magmatic activities in the area at around 130 Ma. Full article

The Jiaodong gold province is one of the most important gold fields globally and the largest in China. The Denggezhuang gold deposit is situated in the eastern portion of the Muping metallogenic belt, within the Jiaodong gold province. Despite many recent investigations, detailed mineralogical studies, particularly on auriferous minerals such as pyrite, are lacking. Therefore, further constraints on the occurrence mode and source of gold are necessary for this deposit. This study employed in situ laser ablation (multi-collector) inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) trace element and sulfur-lead isotopic analyses on pyrite at different stages. The aim was to reveal the occurrence status of various trace elements within Denggezhuang pyrite and to trace the complete evolution process of multi-stage fluids at Denggezhuang, elucidating the sources of gold mineralization. Four generations of pyrite in chronological order, Py-1, Py-2a, Py-2b, and Py-3, were identified via petrographic and backscattered electron (BSE) image analyses. Using in situ LA-MC-ICP-MS, we found that Co and Ni are most abundant in Py-1, while Py-2b is rich in As, Au, Ag, Pb, and Zn, reflecting the evolution of the mineralizing fluids in different mineralization stages. Py-2b contains a significant amount of invisible lattice gold, which migrates and precipitates within fluids rich in As. The in situ LA-MC-ICP-MS S-Pb isotopic analysis of pyrite indicates a relatively consistent source of ore-forming materials across different stages. Additionally, the S-Pb isotope characteristics resemble those of widely distributed coeval mafic dikes. Therefore, we propose that a water-rich, fertile, and deep-seated mafic magmatic system might have provided fluids, materials, and heat for mineralization. Full article