High 3He/4He ratios in the Wangu gold deposit, Hunan province, China: Implications for mantle fluids along the Tanlu deep fault zone.

Mao, Jingwen; Kerrich, Robert; Li, Hongyan; Li, Yanhe

doi:10.2343/geochemj.36.197

Cited by 54 publications

(16 citation statements)

References 34 publications

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“…The new fluid inclusion and rare gas data from our study are similar to those from other deposits along the margins of the North China craton. The high 3 He/ 4 He ratios are analogous to those (3-7.2 Ra) in carbon dioxide gas reservoirs in a subsiding basin developed along the Tan-Lu fault in eastern China (Xu et al, 1995) and are similar to those (3.5-9.8 Ra) from the 120 Ma Wangu orogenic gold deposit adjacent to the Tan-Lu fault (Mao et al, 2002a). Analyses of inclusion fluids in pyrite from auriferous and barren quartz veins in the Wangu deposit (Mao et al, 2002a) are separated into two rare gas groups, which are interpreted as having been dominantly sourced in the mantle and crust, respectively (Fig.…”

Section: Sources Of Ore Fluidsmentioning

confidence: 55%

“…Their 3 He/ 4 He ratio is 6 to 100 times higher than that of fluids typical of a crustal origin (Mamyrin and Tolstikhin, 1984;Azbel and Tolstikhin 1990), which requires helium input from a mantle source into the ore fluids. Many syngenetic and epigenetic metallic ore deposits, including porphyry copper and orogenic gold deposits, have been reported as showing involvement of mantlederived components based on helium isotope studies (Simmons et al, 1987;Stuart et al, 1995;Hu et al, 1998;Burnard et al, 1999;Kendrick et al, 2001;Mao et al, 2002a). All of the The 40 Ar/ 36 Ar ratios range from 309 to 632 for the Dongping fluid inclusions and are all only slightly higher than that of atmospheric argon.…”

Section: Resultsmentioning

confidence: 99%

“…Fluids of auriferous quartz veins reflect a dominant mantle-derived source, whereas those of auriferous K-feldspar display a dominant meteoritic source and mixed more radiogenic 4 He and 40 Ar. The fluids in the pyrite from the Wangu gold deposit hosted in subsidiary fractures of the regional strike-slip Tan-Lu fault system show that the auriferous quartz veins have a dominant mantle-derived source and the barren quartz veins represent the pure crustal end member (Mao et al, 2002a). characterizes orogenic gold deposits or the magmatic exsolution model for intrusion-related gold systems does not explain the mantle-related helium at Dongping.…”

Section: Proposed Mineralization Modelmentioning

confidence: 91%

“…Sulfur, oxygen, and carbon isotope data from the Dongping deposit also do not discriminate between either a magmatic or metamorphic fluid source (Song and Zhao, 1996;Hart et al, 2002). Newton et al (1980), Groves et al (1988), and Mao et al ( , 2002a additionally suggested such low-salinity, CO 2 -rich compositions to be consistent with fluids derived from mantle degassing or, at least, indicative of some participation of mantle fluids in the mineralization process.…”

Section: Sources Of Ore Fluidsmentioning

confidence: 99%

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Fluid Inclusion and Noble Gas Studies of the Dongping Gold Deposit, HebeiProvince, China: A Mantle Connection for Mineralization?

et al. 2003

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The Dongping gold deposit (>100 t Au) occurs about 200 km inboard of the northern margin of the North China craton. The deposit is mainly hosted by syenite of a middle Paleozoic alkalic intrusive complex that was emplaced into Late Archean basement rocks. Both groups of rocks are intruded by Late Jurassic to Early Cretaceous crustal-melt granite dikes and stocks, some within a few kilometers of the deposit. The gold ores were deposited during this latter magmatic period at about 150 Ma, a time that was characterized by widespread regional north-south compression that formed the east-west-trending Yanshan deformational belt. The ores include both the telluride mineral-bearing, low sulfide quartz veins and the highly K-feldspar-altered syenite, with most of the resource concentrated in two orebodies (1 and 70). Fluid inclusion microthermometry indicates heterogeneous trapping of low-salinity (e.g., 5-7 wt % NaCl equiv) fluids that varied from a few to 60 mole percent nonaqueous volatile species. Laser Raman spectroscopy confirms that the vapor phase in these inclusions is dominated by CO 2 but may be comprised of as much as 9 mole percent H 2 S and 20 mole percent N 2 ; methane concentrations in the vapor phase are consistently <1 mole percent. The variable phase ratios are consistent with fluid immiscibility during ore formation. Fluid inclusion trapping conditions are estimated to be 250°to 375°C and 0.6 to 1.0 kbar. Helium isotope studies of fluid inclusions in ore-stage pyrites indicate 3 He/ 4 He ratios of 2.1 to 5.2 Ra (Ra = 1.4 × 10-6 for air) for orebody 1 and 0.3 to 0.8 Ra for orebody 70. The former data suggest that at least 26 to 65 percent mantle helium occurs in the fluids that deposited the veins in orebody 1. The lower values for orebody 70, which is characterized by a more disseminated style of gold mineralization, are interpreted to reflect an increased interaction of ore fluids with surrounding crustal rocks, which may have contributed additional 4 He to the fluids. A mantle source for at least some of the components of the gold-forming fluid is consistent with upwelling of hot asthenosphere and erosion of as much as 100 to 150 km of cool Archean lithosphere beneath the craton during this time. The Dongping deposit is located along the 100-km-wide north-south gravity lineament, which marks the western border of the thinned crust. As both regional metamorphism of Mesoproterozoic and younger cover rocks, and widespread granite magmatism, also occurred at ca. 150 Ma, it is unclear as to whether one or both of these also contributed fluid and/or metals to the hydrothermal system. Importantly, these new data suggest that economically significant gold deposits of similar mineral style and fluid composition, which are scattered along the margins of the craton, may all be products of a fluid originally partly sourced within the mantle.

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Section: Sources Of Ore Fluidsmentioning

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Proposed Mineralization Modelmentioning

confidence: 91%

Section: Sources Of Ore Fluidsmentioning

confidence: 99%

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Fluid Inclusion and Noble Gas Studies of the Dongping Gold Deposit, HebeiProvince, China: A Mantle Connection for Mineralization?

et al. 2003

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“…High values of the ratio R / R a for 3 He/ 4 He are diagnostic of injection of mantle He (Oxburgh et al 1986). The increase in R / R a values along the flowpath (Table S1), although not direct evidence of CO 2 injection, is direct evidence that magmatic gas is being added to the aquifer; CO 2 is almost always the main component of magmatic outgassing (White and Waring 1963; Mao et al 2002). Input of magmatic CO 2 causes HCO 3 − concentration to increase via two mechanisms—dissolution of CO 2 followed by conversion to HCO 3 − (given that the pH of San Bernardino water ranges from 6.7 to 8.3, nearly all magmatic CO 2 that dissolves will be converted to HCO 3 − ) and by providing a needed reactant for weathering of basin alluvium by silicate hydrolysis (Earman et al 2005).…”

Section: Hydrogeologymentioning

confidence: 98%

Tectonic Influences on Ground Water Quality: Insight from Complementary Methods

et al. 2008

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A study using multiple techniques provided insight into tectonic influences on ground water systems; the results can help to understand ground water systems in the tectonically active western United States and other parts of the world. Ground water in the San Bernardino Valley (Arizona, United States and Sonora, Mexico) is the main source of water for domestic use, cattle ranching (the primary industry), and the preservation of threatened and endangered species. To improve the understanding of ground water occurrence, movement, and sustainability, an investigation was conducted using a number of complementary methods, including major ion geochemistry, isotope hydrology, analysis of gases dissolved in ground water, aquifer testing, geophysics, and an examination of surface and subsurface geology. By combining information from multiple lines of investigation, a more complete picture of the basin hydrogeology was assembled than would have been possible using fewer methods. The results show that the hydrogeology of the San Bernardino Valley is markedly different than that of its four neighboring basins in the United States. The differences include water quality, chemical evolution, storage, and residence time. The differences result from the locally unique geology of the San Bernardino Valley, which is due to the presence of a magmatically active accommodation zone (a zone separating two regions of normal faults with opposite dips). The geological differences and the resultant hydrological differences between the San Bernardino Valley and its neighboring basins may serve as a model for the distinctive nature of chemical evolution of ground water in other basins with locally distinct tectonic histories.

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Mineralogy and He–Ar isotopic compositions of pyrites in the Paishanlou Au deposit on the northern margin of North China Craton

et al. 2019

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The Paishanlou Au deposit is an altered‐rock type with the magmatic‐hydrothermal type deposit on the northern margin of the North China Craton and hosts a resource of ~40 tonnes Au. The deposit is hosted in the Neoarchean metamorphic rocks of the Jianping Group and is controlled mainly by ENE–NW‐trending ductile shear zones. The orebodies are stratoid, and mineralization styles are divided into auriferous altered felsic mylonite and altered biotite plagioclase mylonite. The sulphide minerals are dominated by pyrite that is recognized as pyrite 1, pyrite 2, and pyrite 3 based on crystalline form and structure, and pyrite 2 is the main auriferous mineral. Three types of pyrite were selected for electron microprobe analysis (EPMA), and the results show S deficiency, indicating that the pyrites are formed in reducing conditions. The pyrites have a trend from being Fe deficient to being Fe enriched, suggesting that the crystallization rate increases with the decrease of impurity composition from the early to the late stage. The Co/Ni ratios and Co–Ni–As diagram reflect that the Paishanlou Au deposit is associated with magmatic‐hydrothermal and is affected by various hydrothermal. He–Ar isotopic analyses of auriferous pyrite 2 indicate that the ore‐forming fluids are mixtures of mantle‐derived and modified air‐saturated water (MASW). 3He/4He ratios range from 0.21 to 1.51 Ra (Ra = 1.39 × 10−6 for air), corresponding to a 2.18%–19.06% mantle He contribution. The formation of mixed ore‐forming fluids was related to magmatism associated with craton destruction during the Early Cretaceous. Also, we attempt to use the thermoelectric characteristics of pyrite and a contour chart of Au grades to indicate potential mineralization prospecting areas.

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High 3He/4He ratios in the Wangu gold deposit, Hunan province, China: Implications for mantle fluids along the Tanlu deep fault zone.

Cited by 54 publications

References 34 publications

Fluid Inclusion and Noble Gas Studies of the Dongping Gold Deposit, HebeiProvince, China: A Mantle Connection for Mineralization?

Fluid Inclusion and Noble Gas Studies of the Dongping Gold Deposit, HebeiProvince, China: A Mantle Connection for Mineralization?

Tectonic Influences on Ground Water Quality: Insight from Complementary Methods

Mineralogy and He–Ar isotopic compositions of pyrites in the Paishanlou Au deposit on the northern margin of North China Craton

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