Calculation of sulfur isotope fractionation in sulfides

Li, Yongbing; Liu, Jianming

doi:10.1016/j.gca.2005.12.015

Cited by 144 publications

(47 citation statements)

References 35 publications

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“…These differences are substantially greater than the <1‰ equilibrium isotope fractionation predicted between chalcopyrite and fluid H 2 S (KAJIWARA and KROUSE, 1971;LI and LIU, 2006), and are somewhat unexpected at the high-temperature, acidic conditions in black smoker vent fluids (OHMOTO and LASAGA, 1982). Several explanations have been invoked to account for the observed disequilibria, including kinetic fractionation during precipitation (KERRIDGE et al, 1983), or changes in the sulfur isotopic composition of vent fluid H 2 S over time due to variations in the relative proportions of basalt-derived versus seawater SO 4 δ 34 S H 2 S reduction-derived H 2 S (BLUTH and OHMOTO, 1988;WOODRUFF and SHANKS, 1988;SHANKS et al, 1998).…”

Section: Fractionation During Sulfide Precipitationmentioning

confidence: 70%

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Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea

McDermott¹

2015

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THESIS ABSTRACTThis thesis examines the controls on organic, inorganic, and volatile species distributions in hydrothermal fluids venting at Von Damm and Piccard, two recently discovered vent fields at the ultraslow spreading Mid-Cayman Rise, Earth's deepest mid-ocean ridge. A wide variety of possible temperatures and substrates for fluid/rock reaction exist at ultraslow spreading ridges. The flux of chemicals delivered to the ocean by circulating vent fluids exerts a major control on mass transfer into and out of the oceanic crust and supports chemosynthetic ecosystems. In Chapter 2, abiotic organic synthesis is shown to occur via two distinct mechanisms in the serpentinizing Von Damm system. Longstanding questions concerning the spatial, temporal, and mechanistic nature of carbon transformations in deep-sea hot springs are addressed. In contrast with the current paradigm, CH 4 is not actively forming during circulation of H 2 -rich vent fluids, but instead is derived from fluid inclusions in the host rocks. Chapters 3 and 4 present in-depth studies of the chemical and isotopic compositions of aqueous species in vent fluids at Von Damm and Piccard to elucidate the role of reaction temperature, pressure, substrate composition, and water/rock mass ratios during the chemical evolution of hydrothermal fluids at oceanic spreading centers. At Von Damm, sequential reaction of gabbroic and peridotite substrates at intermediate temperatures can explain generation of the observed fluids. Geochemical modeling shows that talc-quartz assemblage is expected to precipitate during fluid mixing with seawater at the seafloor. At Piccard, extremely high temperature subsurface water/rock reaction results in high temperature fluids that are richer in dissolved H 2 than any previously observed fluids worldwide. At both locations, high-H 2 conditions promote the abiotic reduction of ΣCO 2 to formate species, which may fuel a subsurface biosphere. In Chapter 5, multiple sulfur isotopes were measured on metal sulfide deposits, S 0 , and fluid H 2 S to constrain sulfur sources and the isotopic systematics of precipitation in a wide variety of seafloor hydrothermal vents. Areas studied include the eastern Manus Basin and Lau Basin back-arc spreading centers, the unsedimented basalt-hosted Southern East Pacific Rise, and the sediment-hosted Guaymas Basin mid-ocean ridge spreading centers. Limited isotope fractionation between fluid H 2 S and precipitating chalcopyrite implies that sulfur isotopes in a chimney lining may record past hydrothermal activity. ACKNOWLEDGEMENTSFirst, I would like to thank my co-advisor, Jeff Seewald, whose limitless scientific creavitity and sunny outlook have been a continual source of encouragement throughout the 5 years of my doctoral education and research. Jeff's gift for simultaneously challenging and motivating me has taught me many lasting lessons. His limitless optimism and imagination have left permanent impressions on my approach to scientific research, and will not be far from mind when I mentor oth...

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Section: Fractionation During Sulfide Precipitationmentioning

confidence: 70%

“…2). A more recent study (LI and LIU, 2006) reports a calculated of the same magnitude but with opposite sign, such that chalcopyrite is 34 S-enriched with respect to H 2 S by ~0.1‰.…”

Section: Fractionation During Sulfide Precipitationmentioning

confidence: 81%

Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea

McDermott¹

2015

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“…The fractionation between chalcopyrite and pyrite (Kajiwara & Krouse 1971) (Table 3) with chalcopyrite and pyrite (Kajiwara & Krouse 1971;Li & Lui 2006). The S-isotope equilibrium fractionations between galena and chalcopyrite at Cononish give low temperatures that might reflect cooling during the development of the paragenesis.…”

Section: S-isotope Fractionations Between Mineral Pairsmentioning

confidence: 99%

How the Neoproterozoic S-isotope record illuminates the genesis of vein gold systems: an example from the Dalradian Supergroup in Scotland

Hill

Jenkin

Boyce

et al. 2013

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The genesis of quartz vein-hosted gold mineralization in the Neoproterozoic-early Palaeozoic Dalradian Supergroup of Scotland remains controversial. An extensive new dataset of S-isotope analyses from the Tyndrum area, together with correlation of the global Neoproterozoic sedimentary S-isotope dataset to the Dalradian stratigraphy, demonstrates a mixed sedimentary and magmatic sulphur source for the mineralization. d34 S values for early molybdenite-and later gold-bearing mineralization range from 22 to +12‰, but show distinct populations related to mineralization type. Modelling of the relative input of magmatic and sedimentary sulphur into gold-bearing quartz veins with d 34 S values of +12‰ indicates a maximum of 68% magmatic sulphur, and that S-rich, SEDEX-bearing, Easdale Subgroup metasedimentary rocks lying stratigraphically above the host rocks represent the only viable source of sedimentary sulphur in the Dalradian Supergroup. Consequently, the immediate host rocks were not a major source of sulphur to the mineralization, consistent with their low bulk sulphur and lack of metal enrichment. Recent structural models of the Tyndrum area suggest that Easdale Subgroup metasedimentary rocks, enriched in 34 S, sulphur and metals, are repeated at depth owing to folding, and it is suggested that these are the most likely source of sedimentary sulphur, and possibly metals, for the ore fluids.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

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“…A detailed discussion about sulfur isotopic fractionation at magmatic to hydrothermal conditions is beyond the scope of this study, but can be found in the literature (e.g., Field and Gustafson, 1976;Ohmoto and Rye, 1979;Hoefs, 1987;Ishihara and Sasaki, 1989;Rollinson, 1993;Ohmoto and Goldhaber, 1997;Field et al, 2005;Li and Liu, 2006). However, it is noted that sulfate species tend to be enriched in 34 S relative to sulfide species at magmatic temperatures.…”

Section: Discussionmentioning

confidence: 93%

Estimate of mole sulfate ratios in magmatic rocks

Yang¹,

Lentz²

2009

Geochem. J.

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This study presents a numerical method to estimate the mole fractions of sulfate species in magmatic rocks using sulfur isotopes, which can be illustrated in a δ-δ diagram. The mole sulfate ratio in an igneous rock sample can be calculated from the δ 34 S rock value of the whole-rock sample and the δ 34 S sulfide (or δ 34 S sulfate ) value of a sulfide and (or) a sulfate mineral (species) in the sample on the basis of S-isotope fractionation and mass balance under the conditions of magmatic equilibrium. This method can be used to test if magmatic equilibrium between sulfate and sulfide species in magmatic rocks is retained, and to predict the δ 34 S value of one of them at a certain temperature if sulfur isotopic equilibrium is maintained. The initial sulfur isotope composition of the system in question may be estimated based on a set of samples from an igneous suite. Mole sulfate ratio in the magmatic rocks is then used to estimate redox conditions under which they are formed. This practice is important in understanding the genesis of mineral deposits associated with magmatic rocks.

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Calculation of sulfur isotope fractionation in sulfides

Cited by 144 publications

References 35 publications

Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea

Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea

How the Neoproterozoic S-isotope record illuminates the genesis of vein gold systems: an example from the Dalradian Supergroup in Scotland

Estimate of mole sulfate ratios in magmatic rocks

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