Ore geology and fluid inclusions of the Hucunnan deposit, Tongling, Eastern China: Implications for the separation of copper and molybdenum in skarn deposits

Cao, Yi; Zheng, Z; Du, Yu; Gao, Fuping; Xinlong, Qin; Yang, Haibo; Lu, Yao

doi:10.1016/j.oregeorev.2016.04.013

Cited by 26 publications

(10 citation statements)

References 48 publications

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“…This is consistent with the view that large-scale Cu-Mo polymetallic mineralization is closely related to high oxygen fugacity magmas [102][103][104][105][106][107][108][109]. Previous studies on the ore-forming fluid of the deposit showed that the time changes of redox conditions, acid balance, and temperature in the ore-forming fluid led to the temporal separation of copper and molybdenum in Hucunnan skarn deposit [37]. Research on the major elements and S-Pb isotopes of pyrite showed that the ore-forming materials of skarn and porphyry orebody in this deposit have similar sources.…”

Section: Metallogenic Modelsupporting

confidence: 90%

“…Previous studies held that the ages of quartz diorites and granodiorite of Hucunan deposit are 125 Ma and 137.5 Ma, respectively [36]. The H-O isotopic signatures and the study of fluid inclusions show that the ore-forming fluids were dominated by magmatic water in the early stages, and gradually mixed with circulating meteoric water in the late stages [37]. However, there is still a lack of research on the magmatic evolution and source of ore-forming materials.…”

Section: Introductionmentioning

confidence: 99%

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Geochemical Study of Cretaceous Magmatic Rocks and Related Ores of the Hucunnan Cu–Mo Deposit: Implications for Petrogenesis and Poly-Metal Mineralization in the Tongling Ore-Cluster Region

Yang

et al. 2020

Minerals

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The Hucunnan porphyry- and skarn-type Cu–Mo deposit is located in the south of the central Shizishan ore field of the Tongling ore-cluster region. The intrusive Hucunnan granodiorite, outcropping in this deposit, has adakitic geochemical features, and its magma is proposed to have originated from partial melting of the oceanic crust mixed with mantle-derived materials. The porphyry-type orebody is hosted in the granodiorite, whereas the skarn-type orebody occurs in the contact zones of intrusions and country rocks. The δ34S values of pyrite from the skarn orebodies ranged from +3.9 to +4.7‰ (avg. +4.3‰, n = 6), while those of the porphyry orebodies ranged from +5.1 to +6.2‰ (avg. +5.6‰, n = 4). 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios of the pyrites from the skarn orebodies were 38.04–38.45 (avg. 38.26), 15.55–15.66 (avg. 15.59), and 18.16–18.54 (avg. 18.44), respectively (n = 6). The pyrites in the porphyry orebodies had 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios of 38.24–38.36, 15.51–15.662, and 18.10–18.41, respectively (avg. 38.32, 15.58, 18.22; n = 4), respectively. The metallogenic model ages from Re–Os isotopic dating were 138.7 ± 1.9 and 140.0 ± 2.8 Ma, respectively. Geochemical data indicate that the ore-forming fluids in the skarn stage are characterized by high temperature, low acidity, and high oxygen fugacity, and the ore-forming materials were mainly from magma and partly from stratum, proving that the skarn orebody has more stratum materials than the porphyry orebody.

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Section: Metallogenic Modelsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Geochemical Study of Cretaceous Magmatic Rocks and Related Ores of the Hucunnan Cu–Mo Deposit: Implications for Petrogenesis and Poly-Metal Mineralization in the Tongling Ore-Cluster Region

Yang

et al. 2020

Minerals

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“…Previous experiment studies demonstrate that the bulk of the dissolved Cu in brine would precipitate on cooling from 350°C to 250°C (Xiao, Gammons, & Williams‐Jones, ). Fluid boiling may have been the major drive force for chalcopyrite precipitation in many hydrothermal deposits (Cao et al, ; Wang et al, ; and references therein). Boiling would decrease the temperature of ore fluid and significantly increase its pH and decrease its oxygen fugacity due to the escape of acidic volatiles (e.g., CO 2 component; Chen, Pirajno, Li, Guo, & Lai, ; Fan, Hu, Wilde, Yang, & Jin, ; Zhong et al, ; and references therein).…”

Section: Discussionmentioning

confidence: 99%

Genesis and hydrothermal evolution of the Tiantangshan tin‐polymetallic deposit, south‐eastern Nanling Range, South China

et al. 2018

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The Tiantangshan tin‐polymetallic deposit, located in the Nanling Range of South China, is a medium‐sized polymetallic deposit found in the region in recent years. The deposit is hosted within volcanic rocks, and the orebodies occur in the cupola and outer contact zone of the concealed quartz porphyry, as well as the altered fracture zone of the volcanic rocks close to the intrusive contact. In light of field evidence and petrographic observations, the mineralization can be divided into four stages: greisenization stage (stage I), quartz–cassiterite–wolframite stage (stage II), quartz–fluorite–cassiterite–sulfides stage (stage III), and post‐ore stage (stage IV). Three types of fluid inclusions are present in the hydrothermal topaz, quartz, and fluorite, including H2O‐rich (W‐type, WL‐ and WV‐ subtypes), CO2‐bearing (C‐type), and solid‐bearing (S‐type). Four stages of fluid evolution are observed by detailed fluid inclusion studies: (a) Stage I fluids are trapped under two‐phase immiscible condition, as evidenced by the coexistence of primary aqueous (W‐type) and aqueous‐carbonic (C‐type) fluid inclusions preserved in topaz and quartz; the fluid inclusions display homogenization temperatures of 378–448°C and salinities of 6.0–17.5 wt.% NaCl equiv. (b) Similarly, fluid inclusions in stage II quartz also record immiscible condition, as identified by the coexistence of W‐type and C‐type fluid inclusions with lower homogenization temperatures (308–400°C) and salinities (1.8–14.5 wt.% NaCl equiv.). (c) Stage III fluids are characterized by the coexistence of widespread WL‐subtype, minor S‐type, and rare WV‐subtype fluid inclusions, with similar homogenization temperatures (230–369°C) but contrasting salinities (0.5–39.5 wt.% NaCl equiv.), which indicates an episode of fluid boiling occurred in this stage. (d) Stage IV marks the end of the hydrothermal system characterized by the lower temperatures (175–298°C) and salinities (0.2–3.9 wt.% NaCl equiv.) W‐type fluid inclusions trapped. Microthermometry and H–O isotopes indicate that the early ore‐forming fluids (in stage I) exsolved from the granitic magma and underwent progressive mixing with meteoric water during subsequent ore‐forming process (in stages III and IV). The water–CO2 fluid immiscibility is the main mechanism of cassiterite and wolframite precipitation, while fluid boiling and mixing are probably thought to be the dominant mechanisms for the deposition of sulfide at Tiantangshan. 40Ar/39Ar dating of hydrothermal biotite intergrown with cassiterite shows that tin‐polymetallic mineralization occurred at ~133 Ma which is coeval with the hidden intrusions. Taken together, these lines of evidence confirm that the Tiantangshan deposit is a magmatic hydrothermal greisen–quartz–vein type tin‐polymetallic deposit that formed in the lithospheric extension and thinning setting associated with the postsubduction Paleo‐Pacific Plate tectonic regime that influenced South China.

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“…The formation of molybdenite (MoS 2 ) requires abundant Mo 4+ in mineralizing fluids. Several physicochemical factors ( T , f O2 , acidity, and salinity) can change molybdenum speciation via multiple processes, including cooling, mixing (with meteoric waters), fluid–rock interactions, and boiling (immiscibility; e.g., Cao et al, 2017; Li, Ulrich, et al, 2012; Ni et al, 2015, 2017; Rempel, Williams‐Jones, & Migdisov, 2009; Seo et al, 2012; Wang, Zhang, Liu, et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Genesis and fluid evolution of the Yuku porphyry Mo deposit, East Qinling orogen, China

Xue

Wang

et al. 2021

Geological Journal

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The Yuku is a large porphyry Mo deposit (1.5 Mt at 0.12% Mo) in the Luanchuan ore district of the East Qinling orogen, central China. The economic Mo ore bodies occur as veins, veinlets, and disseminated ore and are developed mainly within the late Mesozoic Yuku porphyritic granite. Molybdenum mineralization is generally associated with potassic and phyllic alteration. Hydrothermal processes in the Yuku deposit are divided into four stages: (I) a quartz–K‐feldspar–biotite ± pyrite stage, (II) a quartz–molybdenite ± pyrite ± K‐feldspar ± sericite stage, (III) a quartz–polymetallic sulphide stage, and (IV) a calcite ± quartz ± fluorite ± pyrite stage. The fluid evolution during these hydrothermal stages was constrained through systematic investigation of fluid inclusions (FIs) and H−O isotopes. Four types of primary or pseudosecondary FIs were recognized in hydrothermal quartz and calcite: two‐phase liquid‐rich inclusions (L‐type), two‐phase vapour‐rich inclusions (V‐type), halite‐bearing (hypersaline) inclusions (H‐type), and three‐phase CO2‐bearing inclusions (C‐type). FIs within Stages I–IV have homogenization temperatures of 375 to >550, 297–400, 198–298, and 149–188°C, with salinities of 0.53–13.18, 0.35–40.23, 5.11–11.81, and 5.71–9.73 wt% NaCl equiv., respectively. In Stage I, coexisting vapour‐rich (V‐type) and liquid‐rich (L‐type) FIs have similar homogenization temperatures (488 to >550°C) and distinct salinities, indicating fluid boiling during the formation of quartz–K‐feldspar–biotite veins at a pressure of 550–700 bar and a lithostatic depth of 2.3–2.8 km. In Stage II, FIs in quartz were also trapped under boiling conditions, as evidenced by coexisting hypersaline H‐type (34.13–40.23 wt% NaCl equiv.) and low‐salinity V‐type (0.35–2.24 wt% NaCl equiv.) inclusions, which formed at temperatures of 309–361°C and hydrostatic depths of 1.0–2.0 km, equivalent to pressures of 100–200 bar. During Stage III, the ore‐forming fluids were cooler (198–298°C) and more dilute (5.11–11.81 wt% NaCl equiv.) due to the involvement of meteoric water, with minimum trapping pressures estimated at <100–150 bar, corresponding to a hydrostatic depth of <1.0 km. In Stage IV, temperatures decreased further to 149–188°C, with lower salinities (5.71–9.73 wt% NaCl equiv.), indicating a post‐ore fluid stage. These data suggest that the mineralizing fluids forming the Yuku Mo deposit changed from early moderate‐ to low‐salinity CO2‐rich fluids in the H2O–NaCl–CO2 system that formed at high temperature and pressure, to late H2O–NaCl low‐salinity fluids that formed at low temperature and pressure. H−O isotopic compositions indicate that the mineralizing fluids had a dominantly magmatic signature but were diluted by meteoric waters. Combining our integrated analysis of the fluid evolution and deposit geology, we propose that fluid boiling and fluid–rock interaction, including intensive potassic alteration, changed the salinity and triggered CO2 escape, leading to a decrease in fO2 and an increase in the acidity of the ore‐forming fluids...

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Ore geology and fluid inclusions of the Hucunnan deposit, Tongling, Eastern China: Implications for the separation of copper and molybdenum in skarn deposits

Cited by 26 publications

References 48 publications

Geochemical Study of Cretaceous Magmatic Rocks and Related Ores of the Hucunnan Cu–Mo Deposit: Implications for Petrogenesis and Poly-Metal Mineralization in the Tongling Ore-Cluster Region

Geochemical Study of Cretaceous Magmatic Rocks and Related Ores of the Hucunnan Cu–Mo Deposit: Implications for Petrogenesis and Poly-Metal Mineralization in the Tongling Ore-Cluster Region

Genesis and hydrothermal evolution of the Tiantangshan tin‐polymetallic deposit, south‐eastern Nanling Range, South China

Genesis and fluid evolution of the Yuku porphyry Mo deposit, East Qinling orogen, China

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