Sulfur-bearing Phases Research Articles

X-ray diffraction reveals two structural transitions in szomolnokite

AbstractHydrated sulfates have been identified and studied in a wide variety of environments on Earth, Mars, and the icy satellites of the solar system. The subsurface presence of hydrous sulfur-bearing phases to any extent necessitates a better understanding of their thermodynamic and elastic properties at pressure. End-member experimental and computational data are lacking and are needed to accurately model hydrous, sulfur-bearing planetary interiors. In this work, high-pressure X-ray diffraction (XRD) and synchrotron Fourier-transform infrared (FTIR) measurements were conducted on szomolnokite (FeSO4·H2O) up to ~83 and 24 GPa, respectively. This study finds a monoclinic-triclinic (C2/c to P1) structural phase transition occurring in szomolnokite between 5.0(1) and 6.6(1) GPa and a previously unknown triclinic-monoclinic (P1 to P21) structural transition occurring between 12.7(3) and 16.8(3) GPa. The high-pressure transition was identified by the appearance of distinct reflections in the XRD patterns that cannot be attributed to a second phase related to the dissociation of the P1 phase, and it is further characterized by increased H2O bonding within the structure. We fit third-order Birch-Murnaghan equations of state for each of the three phases identified in our data and refit published data to compare the elastic parameters of szomolnokite, kieserite (MgSO4·H2O), and blödite (Na2Mg(SO4)2·4H2O). At ambient pressure, szomolnokite is less compressible than blödite and more than kieserite, but by 7 GPa both szomolnokite and kieserite have approximately the same bulk modulus, while blödite’s remains lower than both phases up to 20 GPa. These results indicate the stability of szomolnokite’s high-pressure monoclinic phase and the retention of water within the structure up to pressures found in planetary deep interiors.

Mineralogy and bulk geochemistry of a fumarole at Hverir, Iceland: Analog for acid-sulfate leaching on Mars

AbstractIceland’s Námafjall geothermal area exhibits a range of alteration environments. Geochemical and mineralogical analyses of fumaroles and hot springs interacting with Holocene basaltic lavas at Hverir, and with Pleistocene hyaloclastites atop nearby Námaskar∂, reveal different patterns of alteration depending on the water/rock ratio, degree of oxidation, and substrate composition and age. The focus of this study is a transect of a Hverir fumarole that has formed a bullseye pattern of alteration of a Holocene basaltic lava flow. Surface samples and samples collected from shallow pits were analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) to constrain changes in mineral assemblage and major elemental composition with both distance and depth. Elemental sulfur is concentrated near the vent, with leached deposits with amorphous silica and anatase nearby and kaolinite, hematite, and jarosite/alunite-group sulfate minerals farther out, with smectites and less altered material at the margins, though smaller-scale mineralogical diversity complicates this pattern.Silica phases include amorphous silica (most samples), cristobalite (some samples in the leached part of the apron), and quartz (minor constituent of a few samples). The silica was concentrated through residual enrichment caused by leaching and is accompanied by a significant enrichment in TiO2 (in anatase). The presence of abundant cristobalite in a surface fumarole-altered Holocene basaltic lava flow most likely reflects cristobalite formed during the devitrification of volcanic glass or precipitation from fumarolic vapors, rather than high-temperature processes. Minor, localized quartz likely reflects diagenetic maturation of earlier-formed amorphous silica, under surface hydrothermal conditions. Natroalunite, natrojarosite, and jarosite are all present and even exhibit compositional zonation within individual crystals, showing that under surface hydrothermal conditions, these minerals can form a significant solid solution.The high iron content of the substrate basalt and the prevalence of Fe-sulfates and Fe-oxide spherules among the alteration products makes this geothermal area an especially useful analog for potential martian hydrothermal environments. The residual enrichment of silica in the leached deposits of the Hverir fumarole apron could serve as an acid-sulfate leaching model in which amorphous silica forms without appreciable sulfur-bearing phases in many samples, a possible analog for silica-rich soils in the Columbia Hills on Mars. The coexistence of hematite spherules and jarosite-group minerals serves as an intriguing analog for a volcanic/hydrothermal model for hematite and jarosite occurrences at Meridiani Planum.

Origin of andradite in the Quaternary volcanic Andahua Group, Central Volcanic Zone, Peruvian Andes

Euhedral andradite crystals were found in trachyandesitic (latitic) lavas of the volcanic Andahua Group (AG) in the Central Andes. The AG comprises around 150 volcanic centers, most of wich are monogenetic. The studied andradite is complexly zoned (enriched in Ca and Al in its core and mantle, and in Fe in this compositionally homogenous rim). The core-mantle regions contain inclusions of anhydrite, halite, S- and Cl-bearing silicate glass, quartz, anorthite, wollastonite magnetite and clinopyroxene. The chemical compositions of the garnet and its inclusions suggest their contact metamorphic to pyrometamorphic origin. The observed zoning pattern and changes in the type and abundance of inclusions are indicative of an abrupt change in temperature and subsequent devolatilization of sulfates and halides during the garnet growth. This process is interpreted to have taken place entirely within a captured xenolith of evaporite-bearing wall rock in the host trachyandesitic magma. The devolitilization of sediments, especially sulfur-bearing phases, may have resulted in occasional but voluminous emissions of gases and may be regarded as a potential hazard associated with the AG volcanism.

Insights into sulfur cycling at subduction zones from in-situ isotopic analysis of sulfides in high-pressure serpentinites and ‘hybrid’ samples from Alpine Corsica

Devolatilisation of serpentinites at depth in subduction zones contributes significant quantities of sulfur and other redox sensitive elements to the sub-arc mantle. However, the fate of sulfur in subducted serpentinites is poorly constrained. Textures of sulfur-bearing phases in subducted serpentinites are rarely studied, yet provide important information on the changes to sulfur distribution throughout the subduction cycle and as a result of fluid infiltration. δ34S values of sulfides provide constraints on sulfur sources, the redox state of sulfur in the host mineral, and on processes that have occurred subsequent to sulfide crystallisation, including interaction with oxidised or reduced fluids. Therefore, it is possible to use δ34S values in subducted serpentinites to constrain the redox state of sulfur in sulfides and subduction zone fluids. Furthermore, the proximity of serpentinites to ocean crust and metasediments may influence enrichment or depletion of 34S during subduction relative to serpentinites distal to such lithologies.This study investigates the redox state, the likelihood of sulfur addition to the sub-arc mantle from serpentinite dehydration, and the distribution of sulfur within subducted serpentinites and ‘hybrid’ mafic/ultramafic rocks from Alpine Corsica. The techniques utilised include petrographic analysis, in-situ sulfur isotopic analysis and trace element analysis of sulfides hosted in these rocks. All sulfides investigated have high δ34S values of 1.9–15.5‰, which suggests that mantle-derived sulfur (δ34S ~0.1‰), was not the sole source of sulfur. The highest δ34S values are recorded in pyrites of a hybrid mafic/ultramafic sample. High δ34S values are preserved in sulfides attributed to prograde metamorphism, and is most consistent with the retention of sulfur derived from hydrothermal sulfate reduction on the seafloor. However, a shift towards higher δ34S values in sulfides associated with the advanced stages of exhumation suggests that late stage exhumation enables enhanced access to slab-derived fluids bearing oxidised sulfur (SO42− or SO2). Such fluids may have been derived from the devolatilisation of serpentinite at greater depth, or from other lithologies.

Influence of sulfur on the fate of heavy metals during clinkerization

The fate of heavy metals during clinkerization is of crucial significance to the solid waste utilization, environmental management, and sustainable development. This paper presents a laboratory scale simulation that aims to investigate the effects of sulfur on the fate of Cu, Pb, and Cd during clinkerization. The sulfur-bearing phases (CaSO4·2H2O and CaS) and metal oxides were mixed with cement raw meal in appropriate ratios to produce clinkers. The volatilization and solidification of Cu, Pb and Cd were investigated using atomic absorption spectrometry, thermogravimetric analysis, X-ray diffraction analyses, electron probe X-ray microanalysis, and scanning electron microscopy. The volatilization of Cu slightly increased in the temperature range 950 °C–1450 °C with addition of sulfur. Sulfur promotes the volatilization of Pb and Cd at the temperature from 950 °C to 1250 °C by decreasing the melting point of PbO and CdO. Sulfur increased the solidification ability of clinker decreasing the volatilization ratio of Pb and Cd at the temperature of 1350–1450 °C and 1450 °C, respectively. Both forms of sulfur (CaSO4·2H2O and CaS) have similar effect on the Cu/Pb/Cd volatilization. Sulfur concentrated in interstitial phases of the clinkers mainly as Ca4Al6O12SO4 and CaSO4. Cu, Pb and Cd were mainly solidified within interstitial phases of the clinkers forming solid solutions with the variable compositions. Cu was also present in alite and belite and as crystalline phases of Ca2CuO3 and CaCu2O3 in the clinkers. This research can help to improve understanding of the fate of heavy metals and provide a guideline for risk assessment during the co-processing of solid wastes in cement kiln.

Gas and ash emissions associated with the 2010–present activity of Sinabung Volcano, Indonesia

Sinabung Volcano (Sumatra, Indonesia) awoke from over 1200years of dormancy with multiple phreatic explosions in 2010. After a period of quiescence, Sinabung activity resumed in 2013, producing frequent explosions, lava dome extrusion, and pyroclastic flows from dome and lava flow collapses, becoming one of the world's most active volcanoes and displacing over 20,000 citizens. This study presents a compilation of the geochemical datasets collected by the Indonesian Center for Volcanology and Geological Hazard Mitigation (CVGHM) from 2010–current (2016), which provides insights into the evolution of the eruption. Based on observations of SO2 emissions, ash componentry, ash leachate chemistry, and bulk ash geochemistry, the eruption can be split into six distinct geochemical phases. The initial stage of phreatic summit explosions (phase A) occurred from August–September 2010, during which background SO2 emissions averaged ~550±180t/d (1s.d.). An eruptive pause (phase B) starting in October 2010 abruptly ended in September 2013 with a resumption of conduit-clearing eruptions (phase C). This third phase had a relatively modest background SO2 emission rate (avg. ~430±310t/d) and produced ash consisting of accidental ejecta with high S/Cl leachate molar ratios (12.0±8.2, max 34), suggestive of deep-sourced magma and/or the incorporation of hydrothermal sulfur-bearing phases. Lava extrusion at the summit (phase D) began in mid-December 2013, and was accompanied by relatively low SO2 emission rates (360±200t/d) and lower, but variable, S/Cl leachate ratios (6.3±8.5). The most intense phase of the eruption (phase E) occurred from mid-January to late February 2014 following a major lava dome collapse. This period included increased lava extrusion rates, dozens of large eruptions per day, high SO2 emission rates (average: 1680±1070t/d, peak: ~3800t/d), and a dramatic drop in S/Cl ash leachates to ratios (average 1.4±0.5), consistent with increased degassing from shallow magma and the clearing out of sulfurous phases from the old hydrothermal system. From March 2014 through the time of writing (September 2016), Sinabung settled into a relatively steady state of lower activity (phase F). Ash emissions now consist of dominantly juvenile andesitic-dacitic material with low S/Cl leachate ratios (average 1.1±0.6). In August 2016, SO2 emissions started being measured in a continuous manner using a network of permanent scanning DOAS instruments. Background SO2 emission rates average 450±290t/d for the entirety of phase F, but have been progressively decreasing to an average of ~250–300t/d since June 2016. This long-term gradual decline in SO2 emission rates at Sinabung since early 2014 is consistent with an apparent decrease in magma supply and lava effusion rates. Our conceptual degassing model suggests that large explosions and pyroclastic flows could continue in the near-term owing to conduit plugging and dome collapses, remaining a major threat until the magma supply rate decreases further and the eruption ends.

Mass independent sulfur isotope signatures in CMs: Implications for sulfur chemistry in the early solar system

We have investigated the quadruple sulfur isotopic composition of inorganic sulfur-bearing phases from 13 carbonaceous chondrites of CM type. Our samples include 4 falls and 9 Antarctic finds. We extracted sulfur from sulfides, sulfates, and elemental sulfur (S0) from all samples. On average, we recover a bulk sulfur (S) content of 2.11±0.39wt.% S (1σ). The recovered sulfate, S0 and sulfide contents represent 25±12%, 10±7% and 65±15% of the bulk S, respectively (all 1σ). There is no evidence for differences in the bulk S content between falls and finds, and there is no correlation between the S speciation and the extent of aqueous alteration. We report ranges of Δ33S and Δ36S values in CMs that are significantly larger than previously observed. The largest variations are exhibited by S0, with Δ33S values ranging between −0.104±0.012‰ and +0.256±0.018‰ (2σ). The Δ36S/33S ratios of S0 are on average −3.1±1.0 (2σ). Two CMs show distinct Δ36S/33S ratios, of +1.3±0.1 and +0.9±0.1. We suggest that these mass independent S isotopic compositions record H2S photodissociation in the nebula. The varying Δ36S/Δ33S ratios are interpreted to reflect photodissociation that occurred at different UV wavelengths. The preservation of these isotopic features requires that the S-bearing phases were heterogeneously accreted to the CM parent body. Non-zero Δ33S values are also preserved in sulfide and sulfate, and are positively correlated with S0 values. This indicates a genetic relationship between the S-bearing phases: We argue that sulfates were produced by the direct oxidation of S0 (not sulfide) in the parent body. We describe two types of models that, although imperfect, can explain the major features of the CM S isotope compositions, and can be tested in future studies. Sulfide and S0 could both be condensates from the nebula, as the residue and product, respectively, of incomplete H2S photodissociation by UV light (wavelength <150nm). This idea requires that FeS formation and the S0 condensation co-occur. As an alternative, ice accretion to the CM parent body could allow the delivery of S-MIF in CMs. In that case, sulfides would have been the only S-bearing condensate in CM precursors, and S0 would have been derived from the oxidation of H2S trapped in ices, after its photodissociation at low temperature (<500K) in the nebula. In our models, the observations of H2S UV photodissociation is required to occur at the disk surface, and allowed in nebular environments with canonical C/O ratios. Vertical motions in the disk would redistribute phases that condensed at high altitude to the midplane, where they accreted in the phases that make up the chondritic matrix.

The Fate of Sulfur During Fluid-Present Melting of Subducting Basaltic Crust at Variable Oxygen Fugacity

To constrain the effect of redox state on sulfur transport from subducting crust to mantle wedge during fluid-present melting and the stability of sulfur-bearing phases in the downgoing ocean crust, here we report high-pressure phase equilibria experiments on a H2O-saturated mid-ocean ridge basalt with 1 wt % S at variable oxygen fugacity (⁠⁠). Double-capsule experiments were conducted at 2·0 and 3·0 GPa and 950–1050°C, using Co–CoO, Ni–NiO, NixPd1–x–NiO, and Fe2O3–Fe3O4 external buffers. Sulfur content at sulfide saturation (SCSS) or sulfur content at sulfate saturation (SCAS) of experimental hydrous partial melts was measured by electron microprobe. All experiments were fluid-saturated and produced either pyrrhotite- or anhydrite-saturated assemblages of silicate glass, clinopyroxene, garnet, and rutile or titanomagnetite, ± amphibole ± quartz ± orthopyroxene. The silicate partial melt composition evolves from rhyolitic at 950°C to trachydacitic and trachyandesitic at 1050°C with increasing ⁠. At pyrrhotite saturation, melt S contents range from ∼30 ppm S at < FMQ – 1 to ∼500 ppm S at FMQ < ≤ FMQ + 1·1, whereas at anhydrite saturation (⁠ ≥ FMQ + 2·5) melt S concentrations range from ∼700 ppm S to 0·3 wt % S. Mass-balance calculations suggest that the aqueous fluid phase at equilibrium may contain as much as ∼15 wt % S at 1050°C at pyrrhotite saturation (≤ FMQ + 1·1), in agreement with previous estimates, and up to 8 wt % S at anhydrite saturation. Our data also show that decreases markedly with increasing at pyrrhotite saturation, from several thousand at < FMQ – 1 to ∼ 200–400 at FMQ < ≤ FMQ + 1·1, owing to the increase of melt S content. At anhydrite saturation, is very low (<100) but increases with decreasing temperature, in an opposite way to previous observations at pyrrhotite saturation. As a consequence, at T ≤ 900°C, might be in the range 200 ± 100, irrespective of ⁠. The present study confirms that slab partial melts saturated with pyrrhotite are unable to efficiently transport S from slab to mantle wedge, and suggests that slab partial melts in equilibrium with anhydrite also have very limited power to enrich the mantle wedge in S. Importantly, slab-derived aqueous fluids appear to be efficient vectors for the transport of sulfur from slab to mantle wedge at all ⁠. Therefore, S transfer from ocean crust to wedge mantle is not dependent and could take place over a range of conditions, and oxidized slab conditions are not necessarily required to enrich the mantle wedge in S. Finally, depending on the initial amount of sulfur in the slab, the proportion of residual anhydrite and pyrrhotite in the dehydrated slab below the region of formation of arc magmas is likely to be significant and may efficiently be recycled into the deep mantle.

SQUID-SIMS is a useful approach to uncover primary signals in the Archean sulfur cycle.

Many aspects of Earth's early sulfur cycle, from the origin of mass-anomalous fractionations to the degree of biological participation, remain poorly understood--in part due to complications from postdepositional diagenetic and metamorphic processes. Using a combination of scanning high-resolution magnetic superconducting quantum interference device (SQUID) microscopy and secondary ion mass spectrometry (SIMS) of sulfur isotopes ((32)S, (33)S, and (34)S), we examined drill core samples from slope and basinal environments adjacent to a major Late Archean (∼2.6-2.5 Ga) marine carbonate platform from South Africa. Coupled with petrography, these techniques can untangle the complex history of mineralization in samples containing diverse sulfur-bearing phases. We focused on pyrite nodules, precipitated in shallow sediments. These textures record systematic spatial differences in both mass-dependent and mass-anomalous sulfur-isotopic composition over length scales of even a few hundred microns. Petrography and magnetic imaging demonstrate that mass-anomalous fractionations were acquired before burial and compaction, but also show evidence of postdepositional alteration 500 million y after deposition. Using magnetic imaging to screen for primary phases, we observed large spatial gradients in Δ(33)S (>4‰) in nodules, pointing to substantial environmental heterogeneity and dynamic mixing of sulfur pools on geologically rapid timescales. In other nodules, large systematic radial δ(34)S gradients (>20‰) were observed, from low values near their centers increasing to high values near their rims. These fractionations support hypotheses that microbial sulfate reduction was an important metabolism in organic-rich Archean environments--even in an Archean ocean basin dominated by iron chemistry.

Sulfur-bearing phases detected by evolved gas analysis of the Rocknest aeolian deposit, Gale Crater, Mars

The Sample Analysis at Mars (SAM) instrument suite detected SO2, H2S, OCS, and CS2 from ~450 to 800°C during evolved gas analysis (EGA) of materials from the Rocknest aeolian deposit in Gale Crater, Mars. This was the first detection of evolved sulfur species from a Martian surface sample during in situ EGA. SO2 (~3–22 µmol) is consistent with the thermal decomposition of Fe sulfates or Ca sulfites, or evolution/desorption from sulfur-bearing amorphous phases. Reactions between reduced sulfur phases such as sulfides and evolved O2 or H2O in the SAM oven are another candidate SO2 source. H2S (~41–109 nmol) is consistent with interactions of H2O, H2 and/or HCl with reduced sulfur phases and/or SO2 in the SAM oven. OCS (~1–5 nmol) and CS2 (~0.2–1 nmol) are likely derived from reactions between carbon-bearing compounds and reduced sulfur. Sulfates and sulfites indicate some aqueous interactions, although not necessarily at the Rocknest site; Fe sulfates imply interaction with acid solutions whereas Ca sulfites can form from acidic to near-neutral solutions. Sulfides in the Rocknest materials suggest input from materials originally deposited in a reducing environment or from detrital sulfides from an igneous source. The presence of sulfides also suggests that the materials have not been extensively altered by oxidative aqueous weathering. The possibility of both reduced and oxidized sulfur compounds in the deposit indicates a nonequilibrium assemblage. Understanding the sulfur mineralogy in Rocknest materials, which exhibit chemical similarities to basaltic fines analyzed elsewhere on Mars, can provide insight in to the origin and alteration history of Martian surface materials.

Sulfur, sulfides, oxides and organic matter aggregated in submarine hydrothermal plumes at 9°50′N East Pacific Rise

Deep-sea hydrothermal plume particles are known to sequester seawater trace elements and influence ocean-scale biogeochemical budgets. The relative importance of biotic versus abiotic oxidation–reduction and other particle-forming reaction, however, and the mechanisms of seawater trace element sequestration remain unknown. Suspended particulate material was collected from a non-buoyant hydrothermal plume by in situ filtration at 9°50′N East Pacific Rise during a 3-day, 24 sample, time-series. Twenty-three samples were digested for total elemental analysis. One representative sample was selected for particle-by-particle geochemical analyses including elemental composition by X-ray fluorescence, speciation of Fe, S, and C by 1s X-ray absorption near edge structure spectroscopy, and X-ray diffraction. Consistent with past studies, positive linear correlations were observed for P, V, As, and Cr with Fe in the bulk chemistry. Arsenic was associated with both Fe oxyhydroxides and sulfides but not uniformly distributed among either mineral type. Particle aggregation was common. Aggregates were composed of minerals embedded in an organic matrix; the minerals ranged from <20nm to >10μm in diameter. The speciation of major mineral forming elements (Fe, Mn, S) was complex. Over 20 different minerals were observed, nine of which were either unpredicted by thermodynamic modeling or had no close match in the thermodynamic database. Sulfur-bearing phases consisted of polysulfides (S6, S8), and metal sulfides (Fe, Cu, Zn, Mn). Four dominant species, Fe oxyhydroxide, Fe monosulfide, pyrrhotite, and pyrite, accounted for >80% of the Fe present. Particulate Mn was prevalent in both oxidized and reduced minerals. The organic matrix was: (1) always associated with minerals, (2) composed of biomolecules, and (3) rich in S. Possible sources of this S-rich organic matter include entrained near vent biomass and in situ production by S-oxidizing microorganisms. These results indicate that particle aggregation with organic material is prevalent in dispersing hydrothermal plume fluxes, as well as in sinking particulate matter at this site. Particle aggregation and organic coatings can influence the reactivity, transport, and residence time of hydrothermal particles in the water column. Thus a biogeochemical approach is critical to understanding the net effect of hydrothermal fluxes on ocean and sedimentary trace element budgets.

Supercritical carbon dioxide and sulfur in the Madison Limestone: A natural analog in southwest Wyoming for geologic carbon–sulfur co-sequestration

The Madison Limestone on the Moxa Arch, southwest Wyoming, USA contains large volumes (65–95%) of supercritical CO 2 that it has stored naturally for 50 million years. This reservoir also contains supercritical H 2S, aqueous sulfur complexes (SO 4 2− and HS −), and sulfur-bearing minerals (anhydrite and pyrite). Although SO 2 is not present, these sulfur-bearing phases are known products of SO 2 disproportionation in other water–rock systems. The natural co-occurrence of SO 4 2−, S 2−, supercritical CO 2 and brine affords the opportunity to evaluate the fate of a carbon–sulfur co-sequestration scenario. Mineralogic data was obtained from drill core and aqueous geochemical data from wells outside and within the current supercritical CO 2–sulfur–brine–rock system. In addition to dolomite, calcite, and accessory sulfur-bearing minerals, the Madison Limestone contains accessory quartz and the aluminum-bearing minerals feldspar, illite, and analcime. Dawsonite (NaAlCO 3(OH) 2), predicted as an important carbon sink in sequestration modeling studies, is not present. After confirming equilibrium conditions for the Madison Limestone system, reaction path models were constructed with initial conditions based on data from outside the reservoir. Addition of supercritical CO 2 to the Madison Limestone was simulated and the results compared to data from inside the reservoir. The model accurately predicts the observed mineralogy and captures the fundamental changes expected in a Madison Limestone-brine system into which CO 2 is added. pH decreases from 5.7 to 4.5 at 90 °C and to 4.0 at 110 °C, as expected from dissolution of supercritical CO 2, creation of carbonic acid, and buffering by the carbonate rock. The calculated redox potential increases by 0.1 V at 90 °C and 0.15 V at 110 °C due to equilibrium among CO 2, anhydrite, and pyrite. Final calculated Eh and pH match conditions for the co-existing sulfur phases present in produced waters and core from within the reservoir. Total dissolved solids increase with reaction progress, mostly due to dissolution of calcite with an accompanying increase in dissolved bicarbonate. The Madison Limestone is a natural example of the thermodynamic end point that similar fluid–rock systems will develop following emplacement of a supercritical CO 2–sulfur mixture and is a natural analog for geologic carbon–sulfur co-sequestration.

Sulfur Isotope Geochemistry of Sulfide Minerals

Research Article| January 01, 2006 Sulfur Isotope Geochemistry of Sulfide Minerals Robert R. Seal, II Robert R. Seal, II U.S. Geological Survey 954 National Center Reston, Virginia, 20192, U.S.A., e-mail: rseal@usgs.gov Search for other works by this author on: GSW Google Scholar Reviews in Mineralogy and Geochemistry (2006) 61 (1): 633–677. https://doi.org/10.2138/rmg.2006.61.12 Article history first online: 13 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Robert R. Seal; Sulfur Isotope Geochemistry of Sulfide Minerals. Reviews in Mineralogy and Geochemistry 2006;; 61 (1): 633–677. doi: https://doi.org/10.2138/rmg.2006.61.12 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search Sulfur, the 10th most abundant element in the universe and the 14th most abundant element in the Earth’s crust, is the defining element of sulfide minerals and provides insights into the origins of these minerals through its stable isotopes. The insights come from variations in the isotopic composition of sulfide minerals and related compounds such as sulfate minerals or aqueous sulfur species, caused by preferential partitioning of isotopes among sulfur-bearing phases, known as fractionation. These variations arise from differences in temperature, or more importantly, oxidation and reduction reactions acting upon the sulfur. The oxidation and reduction reactions can... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Balmat-Edwards zinc-lead deposits; synsedimentary ore from mississippi valley-type fluids

Reconstruction of some aspects of the initial environment of ore deposition through detailed S, C, and O isotope studies of the Fowler orebody, and through reconnaissance trace element and S isotope studies of sphalerite concentrates and composite samples of ore from 22 orebodies; and (2) evaluation of the effects of high-grade metamorphism on the stable isotope geochemistry of both the ore and gangue minerals of a massive sulfide orebody. The delta 34 S values of pyrite, sphalerite, and galena in the Fowler orebody range from 11.5 to 17.5 per mil; anhydrite associated with ore ranges from 25.6 to 27.0 per mil. Average equilibration temperatures calculated from the delta 34 S differences between coexisting sulfur-bearing phases are 388 degrees C for pyrite-sphalerite, 338 degrees C for sphalerite-galena, 329 degrees C for pyrite-galena, and 602 degrees C for anhydrite-pyrite; all pairs display narrow temperature distributions. The delta 13 C and delta 18 O values of carbonates from the Fowler orebody range from -1.6 to 1.4 per mil and from 24.8 to 27.0 per mil, respectively; quartz delta 18 O values range from 23.0 to 27.0 per mil. The delta 34 S values of sphalerite concentrated from composite samples of the orebodies range from 12.7 to 14.7 per mil. This narrow range contrasts sharply with the wide variability of associated evaporitic anhydrite lenses, which range from 8 to 28 per mil. A stratigraphic increase in the delta 34 S value of the evaporitic anhydrite at Balmat, and large sulfide iron-formation occurrences near Balmat, imply that bacterial sulfate reduction occurred on an unusually large scale during Balmat sedimentation. The presence of such an increase in a sedimentary section may constitute a valuable exploration guide.--Modified journal abstract.

The Genetic Significance of Sulfur Isotopic Analyses from the Jardine-Crevasse Mountain Mining District, Southwestern Montana

The Jardine-Crevasse Mountain area contains the only known economic metal deposits associated with Precambrian rocks in Montana. Previous field investigations indicate that (1) the ores are probably magmatic hydrothermal, (2) the Crevasse Mountain granite was the source of the ore solutions, and (3) the emplacement of the granite ended the Precambrian history in the area. The gold-bearing sulfide ores and sulfurbearing phases from the country rocks and from ore-alteration products have been investigated by sulfur isotopic analyses in order to determine the genesis of the ores and the other sulfur-bearing phases. Ore sulfides range from + 1.0 to + 4.4 permil (8 S34), disseminated sulfides in the country rocks from + 1.6 to + 3.3 permil (8 S34), and alteration products from the ores show: melanterite + 3.7 permil (8 S34) and native sulfur + 4.7 permil (8 S34). The data are consistent with a magmatic hydrothermal origin for both the ore sulfides and the disseminated sulfides, and the higher 8 S34 values for the alteration products indicate that post-ore events have only been of local importance. Introduction The gold-arsenic-tungsten ores and their host and source rocks in the Jardine-Crevasse Mountain area, Southwestern Montana have been investigated by sulfur isotopic variations and by petrographic and mineragraphic studies. The area lies along the north boundary of Yellowstone National Park in Park County, Montana. This area is in the extreme southwest part of the Beartooth-Absaroka uplift. Some of the geology and the sample locations are shown in Figure 1. Early investigations indicated that the ores of the area were not typical of other deposits in Montana as they are the only ones not related to any Tertiary event(s). Seager (1944) has published the only comprehensive study of the area to date and Brown (1965) has recently substantiated many of Seager's earlier conclusions as well as investigating the area by isotopic means. This content downloaded from 207.46.13.159 on Sat, 22 Oct 2016 04:46:00 UTC All use subject to http://about.jstor.org/terms Genetic SigniJc J.X£IE CMSE ..:, ,. ' p , , , ',/01,; ...... / ApAs A ,,,; :, i 10N a X ; v QU 2ZJ.iRY ';' ( _t= = 1 1 ALi j A; tg os ( tY s * <s;) = k aX,, HI Extrusives