Stable Isotope and Fluid Inclusion Constraints on the Source and Evolution of Ore Fluids in the Hongniu-Hongshan Cu Skarn Deposit, Yunnan Province, China

Peng, Huijuan; Mao, Jingwen; Hou, Lin; Shu, Qihai; Zhang, Changqing; Liu, Huan; Zhang, Yang

doi:10.2113/econgeo.111.6.1369

Cited by 63 publications

(25 citation statements)

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“…Combining the finding mentioned above, we can qualitatively interpret that Cu and Mo did not precipitate in the prograde skarn stage of the Fuzishan deposit because of their high solubility in high temperature (>550°C), although immiscibility did occur, similar to that described by Peng et al [48]. Petrographic studies indicate that molybdenum mineralization was earlier than copper mineralization in temporal sequence, probably due to that molybdenite was saturated prior to chalcopyrite at higher temperatures in the retrograde skarn stage, while chalcopyrite subsequently reached saturation in the quartz-sulfide stage.…”

Section: Mechanism For Metal Transportation and Precipitationsupporting

confidence: 88%

“…In addition, CO 2 -bearing FIs and different S-type FIs that are homogenized by halite dissolving after vapor disappearance are generally reported in some skarn Cu and porphyry Cu-Mo deposits [47,52], whereas the Fuzishan deposit does not have this type of FIs, and the fluid inclusion is characterized by occurrence of multiple daughter minerals. Our fluid inclusion studies evidenced that boiling occurred in the prograde skarn stage and quartz-sulfide stage, respectively, which is similar to a fluid evolution model with two-stage fluid phase separation documented in some skarn Cu-Au, Pb-Zn, and Cu deposits [3,48,62]. However, in some porphyry Cu-Mo deposits, only one-stage fluid phase is observed [47].…”

Section: Comparison With Other Cu-mo Deposits Worldwidesupporting

confidence: 85%

“…As mentioned above, V-, V L -, and L V -type inclusions were simultaneously observed within FIAs of quartz, calcite, and late anhydrite in this stage. A "typical" boiling FIA usually contains high-salinity S 1 -type inclusions and low-salinity V L -or V-type inclusions in many skarn and porphyry deposits [3,48]. However, in the Fuzishan deposit, there is no S 1 -type inclusion found in boiling FIAs of the quartz-sulfide stage, similar to that documented by Shu et al [62].…”

Section: Quartz-sulfide Stage (Stage 3)supporting

confidence: 75%

“…The daughter mineral phase of the S 1type inclusions always contains multiple minerals besides halite, including opaque daughter minerals of chalcopyrite, molybdenite, and hematite, transparent daughter minerals of calcite and anhydrite (Figures 8(a)-8(d)). However, this observation of abundant daughter minerals of FIs in the prograde skarn stage was rarely documented in other skarn or porphyry Cu-Mo deposits, such as only halite + opaque daughter minerals which occur in the porphyry Cu-Mo deposit at Butte[47] and halite + sylvite + opaque Fe-bearing daughter minerals in the Hongniu-Hongshan skarn Cu deposit[48]. Most S 1 -type inclusions range from 4 to 45 μm in size, although irregular(Figures 8(a)and 8(c)) and minor negative crystal shapes dominated(Figures 8(b) and 8(d)).…”

mentioning

confidence: 81%

“…Thus, we here approximately take 650°C as the upper limit of the final homogenization temperature in this stage, which facilitates later discussion on pressure estimation. Immiscibility between high-salinity brine and low-density vapor has been documented in many skarn and porphyry deposits [3,4,[48][49][50][51][52][53]. It is proposed that these fluids are generated via fast decompression and slow cooling of the initial supercritical fluid with intermediate salinities (6 to 8 wt.% NaCl equivalent) exsolved from the magma chamber [54][55][56][57][58][59].…”

Section: Prograde Skarn Stage (Stage 1)mentioning

confidence: 99%

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Fluid Evolution of Fuzishan Skarn Cu-Mo Deposit from the Edong District in the Middle-Lower Yangtze River Metallogenic Belt of China: Evidence from Petrography, Mineral Assemblages, and Fluid Inclusions

et al. 2018

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The Fuzishan Cu-Mo deposit is located in the Edong district of the Middle-Lower Yangtze River Metallogenic Belt, China. The orebodies mainly occurred as lenticular and bedded shapes in the skarn zone between the Lower Permian Qixia Formation carbonate rocks and the quartz diorite. Four paragenetic stages have been recognized based on petrographic observations: (1) prograde skarn stage, (2) retrograde skarn stage, (3) quartz-sulfide stage, and (4) carbonate stage. Six fluid inclusion types were recognized: S 1 (vapor + liquid + halite ± other daughter minerals), S 2 (vapor + liquid + daughter minerals except halite), L V (rich liquid + vapor), V L (rich vapor + liquid), V (vapor), and L (liquid) types. Fluid inclusion studies show distinct variations in composition, final homogenization temperature, and salinity in four stages. Daughter minerals of the primary fluid inclusions include chalcopyrite, molybdenite, hematite, anhydrite, calcite, and halite in the prograde skarn stage and hematite, calcite, and sulfide (?) in the retrograde skarn stage. No daughter minerals occurred in the quartz-sulfide and carbonate stages. Final homogenization temperatures recorded in these stages are from 405 to >550°C, from 212 to 498°C, from 150 to 485°C, and from 89 to 223°C, respectively, while salinities are from 3.7 to 42.5, from 2.6 to 18.5, from 2.2 to 17.9, and from 0.2 to 11.5 wt.% NaCl equivalent, respectively. The coexisting V L and S 1 type fluid inclusions show similar homogenization temperature of 550 to about 650°C in the prograde skarn stage, indicating that immiscibility occurred at lithostatic pressure of 700 bars to perhaps 1000 bars, corresponding to a depth of 2.6 km to about 3.7 km. The coeval V L and L V types fluid inclusions with homogenization temperature of 350 to 400°C in the late retrograde skarn and quartz-sulfide stages suggest that boiling occurred under hydrostatic pressure of 150 to 280 bars, equivalent to a depth of 1.5 to 2.8 km. Mo mineralization in the retrograde stage predated Cu mineralization which mainly occurred in the quartz-sulfide stage. Fluid compositions indicate that ore-forming fluid has high fO 2 and rich Cu and Mo concentration in the early stage, while relatively lower fO 2 and poor Cu and Mo concentration in the middle to late stages. Microthermometric data show a decreasing trend in temperature and salinity in the fluid evolution process. Decreasing temperature and boiling event may be the main factors that control the ore precipitation.

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Section: Mechanism For Metal Transportation and Precipitationsupporting

confidence: 88%

Section: Comparison With Other Cu-mo Deposits Worldwidesupporting

confidence: 85%

Section: Quartz-sulfide Stage (Stage 3)supporting

confidence: 75%

mentioning

confidence: 81%

Section: Prograde Skarn Stage (Stage 1)mentioning

confidence: 99%

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Fluid Evolution of Fuzishan Skarn Cu-Mo Deposit from the Edong District in the Middle-Lower Yangtze River Metallogenic Belt of China: Evidence from Petrography, Mineral Assemblages, and Fluid Inclusions

et al. 2018

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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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Regional Metallogenic Models

Li,

Pan,

Hou

et al. 2023

The China Geological Survey Series

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Stable Isotope and Fluid Inclusion Constraints on the Source and Evolution of Ore Fluids in the Hongniu-Hongshan Cu Skarn Deposit, Yunnan Province, China

Cited by 63 publications

References 76 publications

Fluid Evolution of Fuzishan Skarn Cu-Mo Deposit from the Edong District in the Middle-Lower Yangtze River Metallogenic Belt of China: Evidence from Petrography, Mineral Assemblages, and Fluid Inclusions

Fluid Evolution of Fuzishan Skarn Cu-Mo Deposit from the Edong District in the Middle-Lower Yangtze River Metallogenic Belt of China: Evidence from Petrography, Mineral Assemblages, and Fluid Inclusions

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

Regional Metallogenic Models

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