The sulfur isotope evolution of magmatic-hydrothermal fluids: insights into ore-forming processes

Hutchison, William R.; Finch, Adrian A.; Boyce, Adrian J.

doi:10.1016/j.gca.2020.07.042

Cited by 85 publications

(36 citation statements)

References 141 publications

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“…The pyrite (Py2), chalcopyrite, sphalerite, and galena of the Stage II have δ 34 S values of 4.5–5.3, 1.5–4.8, 2.2–3.8, and 2.7–3.0‰, respectively, which is slightly inconsistent with the S isotope fractionation literature data (Ohmoto, 1986; Li and Liu, 2006). Generally, changes in S sources and physico‐chemical conditions (e.g., T, pH, and fO 2 ) and S mineral disequilibrium will cause fluctuations in δ 34 S values (Ohmoto and Rye, 1979; Hutchison et al ., 2020). The detailed mineralogical study showed that various sulfide minerals such as Py2, chalcopyrite, sphalerite, and galena have been formed in the Stage II (Figure 6), suggesting that they precipitated in the same physico‐chemical condition.…”

Section: Discussionmentioning

confidence: 99%

A magmatic‐hydrothermal origin of the Xinfang gold deposit, Liaodong Peninsula, China, revealed by in‐situ S–Pb isotopes and trace element analyses of pyrite

Zeng

Frimmel

et al. 2021

Resource Geology

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The Xinfang deposit is a large gold deposit (>20 t of Au) on the southern edge of the Liaodong Peninsula, China. A total of 37 gold‐bearing orebodies are identified along NS‐ and NW‐striking faults and are mainly hosted by the Archean and Neoproterozoic metamorphic rocks. Three stages of hydrothermal mineralization are distinguished, including Stage I of dominant quartz ± pyrite (Py1), Stage II of quartz‐polymetallic sulfide (Py2), and Stage III of quartz‐calcite ± pyrite (Py3). Gold primarily occurs at the Stage II in association with intensive silicification, pyritization, and sericitization. Here, we report on high‐precision in‐situ LA‐MC‐ICP‐MS analyses of S and Pb isotopic compositions of the sulfide minerals and LA‐ICP‐MS analyses of trace element signature of the pyrite from the Xinfang gold deposit. The δ34S values of the sulfides range from 1.3 to 5.3‰, which is consistent with a magmatic origin of S. The sulfides yield 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios of 37.497–37.773, 15.323–15.410, and 17.004–17.229, respectively, which deviate from the values of the wall rocks, suggesting an external Pb source. The in‐situ LA‐ICP‐MS spot analyses of the pyrite reveals that gold occurs in two generations of pyrite (Py2 and Py3) but at low concentrations (≤0.06 ppm for Py2, ≤0.24 ppm for Py3). Visible gold, however, only occurs in the Stage II assemblage as inclusions in pyrite and quartz, and is distributed along the margins or within the fractures of the sulfides. The Py2 shows high Co, Ni, and As concentrations and is depleted in other trace elements typical of a magmatic‐hydrothermal derivation. In contrast, Py3 exhibits low concentrations in most trace elements. Trace element mapping of Py2 revealed correlations between Fe and Co, as well as Ni and As, indicating their couped substitution in the pyrite structure. The available geological, petrographic and geochemical data consistently suggest that the Xinfang gold deposit formed during the Early Cretaceous by hydrothermal fluids of magmatic contribution.

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Section: Discussionmentioning

confidence: 99%

A magmatic‐hydrothermal origin of the Xinfang gold deposit, Liaodong Peninsula, China, revealed by in‐situ S–Pb isotopes and trace element analyses of pyrite

Zeng

Frimmel

et al. 2021

Resource Geology

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“…The data is available in the electronic annex (Supplementary Table S7). The grey boxes in (A) represent literature data for the isotopic range S sources ( 1 modern sediments (Seal, 2006); 2 meteoric water (Geyh et al, 2000); 3 porphyry fluids (Hutchison et al, 2020); 4 arc volcanic rocks (Falkenberg et al, 2022, and references therein) Modern seawater at ~21‰ is not show in this figure (Rees et al, 1978;Tostevin et al, 2014).…”

Section: Sardesmentioning

confidence: 99%

“…Sulfur isotopes are commonly used in hydrothermal systems to constrain the contribution of S from different sources in the Frontiers in Earth Science frontiersin.org crust (e.g., igneous vs sedimentary rocks) and from magmatic or meteoric fluids (including seawater). In addition, mixing between fluids of different origin changes the isotopic composition and processes like phase separation lead to S isotope fraction, which is typically preserved by the sulfides that form from these fluids (McKibben and Eldridge, 1990;Rye, 2005;Seal, 2006;McDermott et al, 2015;Hutchison et al, 2020). Disproportionation of SO 2 is a common process during ascent and cooling of magma-derived fluids, where 32 S and 34 S fractionate between H 2 S and SO 2− 4 , respectively (Ohmoto and Rye, 1979;Eldridge et al, 2021), as shown by Eq.…”

Section: Insights Into Sulfur Sources and Phase Separation Through δ ...mentioning

confidence: 99%

“…However, fluid inclusions may not always report on the composition of the actual ore-forming fluids, to which the sulfides and the enrichment in critical elements is related (Redmond et al, 2004;Landtwing et al, 2005;Redmond and Einaudi, 2010). How these processes are preserved by the trace element and S isotope signature of hydrothermal sulfides is still debated and poorly investigated in the porphyry environment (Deditius et al, 2011;Reich et al, 2013;Hutchison et al, 2020;Eldridge et al, 2021;González-Jiménez et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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In-situ trace element and S isotope systematics in pyrite from three porphyry-epithermal prospects, Limnos Island, Greece

Börner

Keith²,

Bücker³

et al. 2022

Front. Earth Sci.

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Porphyry-epithermal systems associated with high-K calc-alkaline to alkaline igneous host rocks may be prospective for the recovery of Te among related elements like Cu, Ag, and Au. Limnos Island, as part of the Tethyan magmatic belt, is such an example, where (telescoped) porphyry-epithermal mineralization is accompanied by different alteration-styles reflecting various hydrothermal processes. Here, we present in-situ S isotope and trace element data of pyrite, which records the fluid evolution from the early porphyry to the late epithermal stage in three distinct prospects (Fakos, Kaspakas, Sardes) on Limnos Island. Pyrite in the sericitic alteration of Fakos mainly formed from single-phase magma-derived fluids lacking evidence for phase separation, as reflected by relatively constant δ34S (about −4‰) and Co/Ni (0.1-1) values. By contrast, in the sericitic alteration of Kaspakas and the following epithermal stages, an influence of boiling is implied by negative δ34S values to −15‰, significant intergrain δ34S variations (>3‰), highly variable Co/Ni (100-0.01) and As/Co (10-0.001) in pyrite. Higher δ34S values (above −4‰) in porphyry pyrite from Sardes and partly in the other two hydrothermal systems are related to mixing between magmatic S, and S which was transported through deeply circulated seawater and/or meteoric water. We propose that fluid-rock interaction buffered the pH to higher values, which enhanced the solubility of Au and Te. Subsequent boiling processes caused the Au deposition, whereas Te partitioned into the vapor and finally precipitated upon condensation into meteoric water. This process is accompanied by continuous cooling during fluid ascent from 780°C to <300°C, as indicated by increasing Sb, Tl, and Pb in pyrite from the porphyry to the epithermal stage. Consequently, the in situ δ34S and trace element analysis allows to constrain the depositional environment of economic metals like Au and Te in porphyry-epithermal prospects.

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“…The sulfur stable isotopes (δ 34 S) in sulfates and sulfides have been proven to be a remarkable tool for studying geochemical and biogeochemical cycles in modern and ancient environments [1][2][3]. Particularly, in magmatic-hydrothermal and hydrothermal systems and the associated ore deposits, the δ 34 S values of sulfides routinely provide constraints on the source of sulfur (e.g., magmatic and biogenic) and the processes (e.g., sulfate reduction, fluid mixing, and water-rock interactions) and environmental parameters (e.g., temperature, oxygen fugacity, and pH) associated with sulfide precipitation [4][5][6]. In some peculiar magmatic-hydrothermal and hydrothermal mineral deposits, the mineralogy may be dominated by arsenides, sulfarsenides, and arsenic (As) and mercury (Hg) sulfides.…”

Section: Introductionmentioning

confidence: 99%

Safe, accurate, and precise sulfur isotope analyses of arsenides, sulfarsenides, and arsenic and mercury sulfides by conversion to barium sulfate before EA/IRMS

2022

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The stable isotope ratios of sulfur (δ34S relative to Vienna Cañon Diablo Troilite) in sulfates and sulfides determined by elemental analysis and isotope ratio mass spectrometry (EA/IRMS) have been proven to be a remarkable tool for studies of the (bio)geochemical sulfur cycles in modern and ancient environments. However, the use of EA/IRMS to measure δ34S in arsenides and sulfarsenides may not be straightforward. This difficulty can lead to potential health and environmental hazards in the workplace and analytical problems such as instrument contamination, memory effects, and a non-matrix-matched standardization of δ34S measurements with suitable reference materials. To overcome these practical and analytical challenges, we developed a procedure for sulfur isotope analysis of arsenides, which can also be safely used for EA/IRMS analysis of arsenic sulfides (i.e., realgar, orpiment, arsenopyrite, and arsenian pyrite), and mercury sulfides (cinnabar). The sulfur dioxide produced from off-line EA combustion was trapped in an aqueous barium chloride solution in a leak-free system and precipitated as barium sulfate after quantitative oxidation of hydrogen sulfite by hydrogen peroxide. The derived barium sulfate was analyzed by conventional EA/IRMS, which bracketed the δ34S values of the samples with three international sulfate reference materials. The protocol (BaSO4-EA/IRMS) was validated by analyses of reference materials and laboratory standards of sulfate and sulfides and achieved accuracy and precision comparable with those of direct EA/IRMS. The δ34S values determined by BaSO4-EA/IRMS in sulfides (arsenopyrite, arsenic, and mercury sulfides) samples from different origins were comparable to those obtained by EA/IRMS, and no sulfur isotope fractionations were introduced during sample preparation. We report the first sulfur isotope data of arsenides obtained by BaSO4-EA/IRMS. Graphical abstract

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The sulfur isotope evolution of magmatic-hydrothermal fluids: insights into ore-forming processes

Cited by 85 publications

References 141 publications

A magmatic‐hydrothermal origin of the Xinfang gold deposit, Liaodong Peninsula, China, revealed by in‐situ S–Pb isotopes and trace element analyses of pyrite

A magmatic‐hydrothermal origin of the Xinfang gold deposit, Liaodong Peninsula, China, revealed by in‐situ S–Pb isotopes and trace element analyses of pyrite

In-situ trace element and S isotope systematics in pyrite from three porphyry-epithermal prospects, Limnos Island, Greece

Safe, accurate, and precise sulfur isotope analyses of arsenides, sulfarsenides, and arsenic and mercury sulfides by conversion to barium sulfate before EA/IRMS

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