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Sample records for basalt sulfide saturation

  1. Controls on Highly Siderophile Element Concentrations in Martian Basalt: Sulfide Saturation and Under-Saturation

    NASA Technical Reports Server (NTRS)

    Righter, Kevin

    2009-01-01

    Highly siderophile elements (HSE; Re, Au and the platinum group elements) in shergottites exhibit a wide range from very high, similar to the terrestrial mantle, to very low, similar to sulfide saturated mid ocean ridge basalt (e.g., [1]). This large range has been difficult to explain without good constraints on sulfide saturation or under-saturation [2]. A new model for prediction of sulfide saturation places new constraints on this problem [3]. Shergottite data: For primitive shergottites, pressure and temperature estimates are between 1.2-1.5 GPa, and 1350-1470 C [4]. The range of oxygen fugacities is from FMQ-2 to IW, where the amount of Fe2O3 is low and thus does not have a significant effect on the S saturation values. Finally, the bulk compositions of shergottites have been reported in many recent studies (e.g., [5]). All of this information will be used to test whether shergottites are sulfide saturated [3]. Modeling values and results: The database for HSE partition coefficients has been growing with many new data for silicates and oxides [6-8] to complement a large sulfide database [9- 11]. Combining these data with simple batch melting models allows HSE contents of mantle melts to be estimated for sulfide-bearing vs. sulfide-free mantle. Combining such models with fractional crystallization modeling (e.g., [12]) allows HSE contents of more evolved liquids to be modeled. Most primitive shergottites have high HSE contents (and low S contents) that can be explained by sulfide under-saturated melting of the mantle. An exception is Dhofar 019 which has high S contents and very low HSE contents suggesting sulfide saturation. Most evolved basaltic shergottites have lower S contents than saturation, and intermediate HSE contents that can be explained by olivine, pyroxene, and chromite fractionation. An exception is EET A79001 lithology B, which has very low HSE contents and S contents higher than sulfide saturation values . evidence for sulfide saturation

  2. Interpreting HSE Contents of Planetary Basalts: The Importance of Sulfide Saturation and Under-Saturation

    NASA Technical Reports Server (NTRS)

    Righter, K.

    2000-01-01

    Highly siderophile elements provide important constraints on planetary differentiation due to their siderophile behavior. Their interpretation in terms of planetary differentiation models has so far overlooked the importance of sulfide saturation and under-saturation.

  3. Sulfide Stability of Planetary Basalts

    NASA Technical Reports Server (NTRS)

    Caiazza, C. M.; Righter, K.; Gibson, E. K., Jr.; Chesley, J. T.; Ruiz, J.

    2004-01-01

    The isotopic system, 187Re 187Os, can be used to determine the role of crust and mantle in magma genesis. In order to apply the system to natural samples, we must understand variations in Re/Os concentrations. It is thought that low [Os] and [Re] in basalts can be attributed to sulfide (FeS) saturation, as Re behaves incompatibly to high degrees of evolution until sulfide saturation occurs [1]. Previous work has shown that lunar basalts are sulfide under-saturated, and mid-ocean ridge, ocean-island and Martian (shergottites) basalts are saturated [2,3]. However, little is known about arc basalts. In this study, basaltic rocks were analyzed across the Trans-Mexican Volcanic Belt.

  4. Sulfur release from the Columbia River Basalts and other flood lava eruptions constrained by a model of sulfide saturation

    NASA Astrophysics Data System (ADS)

    Blake, S.; Self, S.; Sharma, K.; Sephton, S.

    2010-11-01

    A very likely cause of widespread environmental impacts of flood basalt eruptions is the emission of sulfur, chlorine, and possibly fluorine from the erupting magma. We present new data on the S contents of rare glass inclusions and matrix glasses preserved in quenched lava selvages from lava fields of the Columbia River Basalt Group (CRBG; Ginkgo, Sand Hollow and Sentinel Gap flows, Wanapum Basalt Formation). We compare these results with published data from Neral and Jawar Formation lavas (Deccan Traps, India) and the Roza flow (CRBG). CRBG glass inclusions have up to 2000 ppm S and 15-16 wt.% FeO total. By contrast, the Deccan examples have about 1400 ppm S and 10 wt.% FeO total. Several of the glass inclusions are partly degassed, indicating entrapment during magma rise, and matrix glasses are typically more evolved than glass inclusions due to small amounts of in situ crystallization. Using only the highest S inclusions and taking account of the effect of in situ crystallization and degassing on the S content of the residual matrix glasses indicates S yields of about 0.07 to 0.1 wt.% from Deccan eruptions and about 0.15 wt.% from Wanapum (CRBG) eruptions. The pre-eruptive S contents of these magmas correlate with weight% FeO total in the same way as undegassed sulfide-saturated mid-ocean ridge basalts. Using oceanic basalts to define a sulfide saturation line, and data on S contents of degassed basalts, we propose an equation to estimate the weight% S yield (ΔS) from initially sulfide-saturated basalt liquid without the need to find well-preserved, rare, undegassed glass inclusions and matrix glasses: ΔS=(0.01418×FeO-0.06381)±0.02635. This compares well with independent estimates derived from the petrologic method by taking the difference in S concentration of glass inclusions and matrix glass. Applying our method to the aphyric Grande Ronde Basalts of the CRBG implies a total yield of about 1000 Gt SO 2 delivered into the Miocene atmosphere in

  5. Sulfide saturation of basalt and andesite melts at high pressures and temperatures

    NASA Technical Reports Server (NTRS)

    Wendlandt, R. F.

    1982-01-01

    When the sulfur content of an Fe-bearing magma exceeds the saturation limit for the bulk composition, an immiscible iron sulfide melt fraction separates. For an understanding of the geochemistry of sulfur-bearing magmatic systems, more information is needed regarding the solubility of metal sulfide in silicate melt at its source and the solubility changes as a function of changing intensive and extensive variables. In the present investigation, the sulfur saturation surface is determined for the pressure range from 12.5 to 30 kbar and the temperature range from 1300 to 1460 C for three silicate melt compositions representing a range of SiO2 and FeO compositions.

  6. Nickeliferous sulfides in xenoliths, olivine megacrysts and basaltic glass

    NASA Astrophysics Data System (ADS)

    Fleet, Michael E.; Stone, William E.

    1990-11-01

    The composition of olivine and nickeliferous sulfide inclusions from a selection of mafic and ultramafre rocks, xenoliths and megacrysts, including picritic basalts from Kilauea Volcano, Hawaii, kimberlite from Fayette County, Pennsylvania, and megacrysts from Mount Shasta, California are compared with the mean experimental value of the distribution coefficient for Ni/Fe exchange (KD3=32). Only nine of the forty five olivipe/bulk-sulfide pairs investigated have compositions consistent with equilibration at high temperature, yielding calculated KD3 values in the range 22 to 41. The remaining pairs have calculated KD3 values which range from 0 to 19. Bulk-sulfides in disequilibrated assem-blages are consistently depleted in nickel and within both indivudual associations and individual petrographic sections they exhibit a wide variation in NiS content. The bulk copper contents of olivine-and groundmass-hosted sulfides from Kilauea Volcano range from 0.5 to 43 at%, and samples from the Kilauea Iki lava lake are more Fe-and Cu-rich and generally have lower KD3 values than those from the eruption itself. As with magmatic Ni-Cu sulfide deposits, most nickeliferous sulfide inclusions in mantle-related rocks and xenoliths and in volcanic rocks do not have pristine early-magmatic bulk compositions, and it would seem to be premature to attribute these sulfides solely to either a mantle or an early-magnatic origin.

  7. Removal of copper from carbon-saturated steel with an aluminum sulfide/iron sulfide slag

    SciTech Connect

    Cohen, A.; Blander, M.

    1995-12-01

    Scrap iron and steel has long been considered a resource in the steel-making industry, and its value is largely determined by its impurity content. As the mini-mills, the major consumers of scrap iron and steel, expand into producing flat-rolled sheet, the demand for high-quality scrap will increase. Of the impurities present in scrap, copper is particularly troublesome because of its role in causing hot shortness. Therefore, the copper content of scrap should be kept below {approx} 0.1 wt%. A method for removing copper from steel could be used to improve the quality of scrap and make it more available for use by mini-mills. To determine the effectiveness of a binary slag consisting of aluminum sulfide and iron sulfide on the removal of copper from steel and iron, the distribution coefficient of copper between the slag and a carbon-saturated iron melt was investigated at 1,365 C. The composition of the slag was varied from nearly pure aluminum sulfide to pure iron sulfide. A maximum distribution coefficient of 30 was found, and the copper level in the iron melt was reduced to as low as 0.07 wt.% with a 4:1 ratio of iron to slag.

  8. Sulfides from Martian and Lunar Basalts: Comparative Chemistry for Ni Co Cu and Se

    SciTech Connect

    J Papike; P Burger; C Shearer; S Sutton; M Newville; Y Choi; A Lanzirotti

    2011-12-31

    Here Mars and Moon are used as 'natural laboratories' with Moon displaying lower oxygen fugacities ({approx}IW-1) than Mars ({approx}IW to FMQ). Moon has lower concentrations of Ni and Co in basaltic melts than does Mars. The major sulfides are troilite (FeS) in lunar basalts and pyrrhotite (Fe{sub 1-x}S) in martian basalts. This study focuses on the concentrations of Ni, Co, Cu, and Se. We chose these elements because of their geochemical importance and the feasibility of analyzing them with a combination of synchrotron X-ray fluorescence (SXRF) and electron microprobe (EPMA) techniques. The selenium concentrations could only be analyzed, at high precision, with SXRF techniques as they are <150 ppm, similar to concentrations seen in carbonaceous chondrites and interplanetary dust particles (IDPs). Nickel and Co are in higher concentrations in martian sulfides than lunar and are higher in martian olivine-bearing lithologies than olivine-free varieties. The sulfides in individual samples show very large ranges in concentration (e.g., Ni ranges from 50 000 ppm to <5 ppm). These large ranges are mainly due to compositional heterogeneities within individual grains due to diffusion and phase separation. Electron microprobe wavelength-dispersive (WDS) mapping of Ni, Co, and Cu show the diffusion trajectories. Nickel and Co have almost identical diffusion trajectories leading to the likely nucleation of pentlandite (Ni,Co,Fe){sub 9}S{sub 8}, and copper diffuses along separate pathways likely toward chalcopyrite nucleation sites (CuFeS{sub 2}). The systematics of Ni and Co in lunar and martian sulfides clearly distinguish the two parent bodies, with martian sulfides displaced to higher Ni and Co values.

  9. The Role of Oxygen Fugacity in Fractionating Parent-Daughter Pairs between Basaltic and Sulfidic Liquids

    NASA Astrophysics Data System (ADS)

    Mershon, R. B.; Jackson, C.; Fei, Y.; Elardo, S. M.; Bennett, N.

    2015-12-01

    Here we examine the effect of oxygen fugacity on trace element partitioning between basaltic and sulfidic liquids. We specifically focus on parent-daughter pairs (Sm-Nd, Re-Os, Lu-Hf, Hf-W, U-Pb, and Th-Pb), such that the isotopic effects associated with sulfide fractionation can be predicted. This work is motivated by recent experiments and observations that suggest Earth experienced massive sequestration of a sulfide liquid to its core during the accretion phase, possibly under extremely reduced conditions. Experiments were run in graphite capsules using a piston-cylinder apparatus (1500°C, 1GPa). Starting compositions comprised ~2/3 of a synthetic MORB and ~1/3 FeS by weight. Oxygen fugacity was varied by adding the Fe component of the MORB starting composition as either FeO or FeSi2. Trace elements were added either as solutions or metal powders. Run durations ranged between one and four hours. The recovered samples were polished using either water or ethanol for lubrication, and then carbon-coated prior to analysis. Major elements were analyzed using a combination of EDS and WDS techniques. Trace element analyses are currently underway. Experiments with iron added as FeSi2 have relatively lower concentrations of O in the sulfide, lower concentrations of Fe in the basalt, and higher concentrations of S in the basalt. These same experiments contained sub-micron CaS and MgS phases within the FeS phase. These observations are consistent with the achievement of very low oxygen fugacity for experiments with FeSi2 added compared to experiments with FeO added. Once trace element partition coefficients are determined, they will be coupled to radiogenic isotope evolution models associated with sulfide fractionation under varying redox conditions.

  10. Partitioning of siderophile and chalcophile elements between sulfide, olivine, and glass in a naturally reduced basalt from Disko Island, Greenland

    NASA Technical Reports Server (NTRS)

    Klock, W.; Palme, H.

    1988-01-01

    Major and trace elements in coexisting glass, olivines, and metal-sulfide spherules from a chilled margin sample of a strongly reduced basaltic dike from Disko Island, Greenland have been investigated. Three sets of partition coefficients are obtained, olivine/silicate liquid and metal-sulfide liquid/silicate liquid partition coefficients established at magmatic temperatures, and FeNi/FeS partition coefficients at lower temperatures. High metal-sulfide liquid/silicate liquid partition coefficients are found for Ni, Sb, As, Mo, Cu, Co, and W. The significance of the present results for planetary evolution and the formation of metal-rich or sulfide-rich metal cores is considered in terms of P, W, and Mo abundances in the mantles of the earth, moon, the Shergotty parent body, and the Eucrite parent body.

  11. Rhenium - osmium heterogeneity of enriched mantle basalts explained by composition and behaviour of mantle-derived sulfides

    NASA Astrophysics Data System (ADS)

    Harvey, J.; Dale, C. W.; Gannoun, A.; Burton, K. W.

    2010-12-01

    Analyses of enriched mantle (EM) -basalts, using lithophile element-based isotope systems have long provided evidence for discrete, but variable mantle reservoirs [1]. Upon partial melting, the isotopic fingerprint of each reservoir is imparted upon the partial melt produced. However, recent work involving the Re-Os isotope systematics of EM-basalts [2] suggests that it may not be so simple to delimit these previously well defined mantle reservoirs; the “mantle zoo” [3] may contain more reservoirs than previously envisaged. However, a simple model, with varying contributions from two populations of compositionally distinct mantle sulfides can readily account for the observed heterogeneities in Re-Os isotope systematics of such basalts without additional mantle reservoirs. Rhenium-osmium elemental and isotopic analyses of individual sulfide grains separated from spinel lherzolites from Kilbourne Hole, NM, USA demonstrate that two discrete populations of mantle sulfide exist in terms of both Re-Os systematics and textural relationship with co-existing silicates. One population, with a rounded morphology, is preserved in silicate grains and typically possesses high [Os], low [Re] with unradiogenic, typically sub-chondritic, 187Os/188Os attributable to long term isolation in a low-Re environment. By contrast, irregular-shaped sulfides, preserved along silicate grain boundaries, possess low [Os], higher [Re] and a wider range of, but generally supra-chondritic, 187Os/188Os ([Os] typically ≤ 1-2 ppm, 187Os/188Os ≤ 0.3729; this study). This population is thought to represent metasomatic sulfide (e.g. [4,5]). Uncontaminated silicate phases contain negligible Os (<100 ppt) therefore the Os elemental and isotope composition of basalts is dominated by volumetrically insignificant sulfide ([Os] ≤ 37 ppm, this study). During the early stages of partial melting, supra-chondritic interstitial sulfides are mobilized and incorporated into the melt, adding their radiogenic

  12. The effect of anhydrite saturation on the fate of sulfur during fluid-present melting of subducting basaltic crust

    NASA Astrophysics Data System (ADS)

    Jego, S.; Dasgupta, R.

    2012-12-01

    The apparent sulfur enrichment of sub-arc mantle is thought to derive from an oxidized downgoing slab, and it has been suggested that the slab-derived sulfate species is responsible for oxidizing the mantle wedge [1]. However, the conditions and extent of sulfur transfer from the subducting slab to the mantle wedge are poorly understood. In particular, the relative mobility of sulfur as a function of oxygen fugacity (fO2) is unconstrained at sub-arc depths. To add to our recent study on sulfur mobility during fluid-present melting of a sulfide-bearing basaltic crust [2], here we constrain the fate of sulfur during similar melting at relatively oxidizing conditions, i.e., at sulfate saturation. Experiments were performed using a piston cylinder device at P = 2-3 GPa, T = 950-1050 °C. A synthetic MORB + 6.8 wt.% H2O doped with 1 wt% S (added as pyrite) was contained in AuPd inner capsules and hematite-magnetite (HM: ~FMQ+3.9 to +4.6) mixture used as fO2 buffer was housed in Pt outer capsules, following the recently proposed design of ref. [3]. Sulfur concentration in quenched silicate glasses, the major element phase compositions, and fO2 of the experiments based on dissolved Fe contents in AuPd and added Pt sensor [4, 5], were determined using EPMA. All experiments contain silicate melt, cpx, garnet, anhydrite, rutile and/or Ti-magnetite, and are fluid saturated. The partial melt compositions are rhyolitic to rhyodacitic with increasing T and melting degree. Sulfur contents in the melt range from ~700 to 3000 ppm, and increase with increasing P and T, in agreement with published SCAS models [6, 7]. Mass balance calculations show that the proportion of sulfur dissolved in silicate melt can be >13% of the bulk sulfur at 1050 °C. However, at slab surface (<900 °C), the major part of the bulk sulfur present in the slab is dissolved in the aqueous fluid phase, the rest being stored as anhydrite crystals. Moreover, our results suggest that sulfur partition coefficient

  13. Experimental determination of Pb partitioning between sulfide melt and basalt melt as a function of P, T and X

    NASA Astrophysics Data System (ADS)

    Hart, Stanley R.; Gaetani, Glenn A.

    2016-07-01

    We have measured the partition coefficient of Pb (KdPb) between FeS melt and basalt melt at temperatures of 1250-1523 °C, pressures of 1.0-3.5 GPa and oxygen fugacities at iron-wustite and wustite-magnetite. The total observed range of KdPb is 4.0-66.6, with a strong negative dependence on pressure and a strong negative dependence on FeO of the silicate melt (Fe+2 only). The FeO control was constrained over a wide range of FeO (4.2-39.5%). We found that the effect of oxygen fugacity can be subsumed under the FeO control parameter. Prior work has established the lack of a significant effect of temperature (Kiseeva and Wood, 2015; Li and Audétat, 2015). Our data are parameterized as: KdPb = 4.8 + (512 - 119*P in GPa)*(1/FeO - 0.021). We also measured a single value of KdPb between clinopyroxene and basalt melt at 2.0 GPa of 0.020 ± 0.001. This experimental data supports the "natural" partitioning of Pb measured on sulfide globules in MORB (Patten et al., 2013), but not the low KdPb of ∼3 inferred from sulfides in abyssal peridotites by Warren and Shirey (2012). It also quantitatively affirms the modeling of Hart and Gaetani (2006) with respect to using sulfide to buffer the canonical Nd/Pb ratio for MORB and OIB (Hofmann, 2003). For the low FeO and pressure of segregation typical of MORB, KdPb ∼ 45, and the Nd/Pb ratio of erupted basalts will be the same as the Nd/Pb ratio of the mantle source. The remaining puzzle is why MORB and OIB have the same Nd/Pb when they clearly have different FeO and pressure of melt segregation.

  14. Mineralogical studies of sulfide samples and volatile concentrations of basalt glasses from the southern Juan de Fuca Ridge

    NASA Technical Reports Server (NTRS)

    Brett, Robin; Evans, Howard T., Jr.; Wandless, M. V.; Gibson, E. K., Jr.; Hedenquist, Jeffrey W.

    1987-01-01

    Sulfide samples obtained from Alvin dives on the southern Juan de Fuca Ridge were examined, showing the presence of two previously undiscovered minerals, both formed at low temperatures. The first detection of lizardite, starkeyite, and anatase in such an environment is also reported. Sulfide geothermometry involving the Cu-Fe-S system shows a vent temperature of less than 328 C for one sample. Ice-melting temperatures on inclusions from this sample are about -2.8 C, and fluid inclusion studies on crystals near this sample show pressure-corrected homogenization temperatures of 268 and 285 C. Volatile concentrations from vesicle-free basalt glass from the vent field are found to be about 0.0013 wt pct CO2 and 0.16 wt pct H2O.

  15. Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge

    SciTech Connect

    Hegner, E.; Tatsumoto, M.

    1987-10-10

    Pb, Sr, Nd isotopes of seven basalt glasses collected by the submersible Alvin from the southern Juan de Fuca Ridge (SJFR) are almost identical (/sup 206/Pb//sup 204/Pbapprox.18.45, /sup 207/Pb//sup 204/Pbapprox.15.47, /sup 208/Pb//sup 204/Pbapprox.37.81, /sup 87/Sr//sup 86/Srapprox.0.70249, /sup 143/Nd//sup 144/Ndapprox.0.51315). Whereas all basalts appear cogenetic, four of the samples have uniform abundances of U, Th, Rb, Nd, Sm, Pb, and Sr, indicating that they are also comagmatic. Two basalt glasses dredged previously at the SJFR have similar isotopic compositions but higher concentrations of U, Th, and Pb. The /sup 206/Pb//sup 204/Pb ratios are intermediate between generally less radiogenic ridge basalts from south of the Juan de Fuca Ridge (JFR) and often more radiogenic basalts from the northern JFR and NE Pacific seamounts. Sr and Nd isotopic compositions closely resemble data of other ridge basalts from the northernmost East Pacific Rise and are intermediate between isotopically more diverse seamount basalts produced nearby.

  16. Siderophile and chalcophile metal variations in Tertiary picrites and basalts from West Greenland with implications for the sulphide saturation history of continental flood basalt magmas

    NASA Astrophysics Data System (ADS)

    Keays, Reid R.; Lightfoot, Peter C.

    2007-04-01

    much more severe than that of the West Greenland contaminated basalts. Moreover, the volumes of the contaminated and metal-depleted volcanic rocks in West Greenland pale is significant when compared to the Nadezhdinsky Formation; local centers rarely contain more than 15 thin flows with a combined thickness of <50 m and more typically 10-20 m, so the volume of the eruptive portions of each system is probably two orders of magnitude smaller than the Nadezhdinsky edifice. The West Greenland centres are juxtaposed along fault zones that appear to be linked to the subsidence of the Tertiary delta, and so emplacement along N-S structures appears to be a principal control on the distribution of lavas and feeder intrusions. This leads us to suggest that the Greenland system is small and segregation of sulphide took place at high levels in the crust, whereas at Noril’sk, the saturation event took place at depth with subsequent emplacement of sulphide-bearing magmas into high levels of the crust. As a consequence, it may be unreasonable to expect that the West Greenland flood basalts experienced mineralizing processes on the scale of the Noril’sk system.

  17. Partitioning of platinum-group elements and Au between sulfide liquid and basalt and the origins of mantle-crust fractionation of the chalcophile elements

    NASA Astrophysics Data System (ADS)

    Mungall, James E.; Brenan, James M.

    2014-01-01

    The partitioning of platinum-group elements (PGE; Os, Ir, Ru, Rh, Pt, and Pd) and Au between sulfide melt and silicate melt (i.e., DPGEsul) exerts a critical control on the PGE composition of the Earth’s crust and mantle, but previous estimates have been plagued by experimental uncertainties and vary through several orders of magnitude. Here we present direct experimental measurements of DPGEsul, based on in situ microanalysis of the sulfide and silicate melt, with values ranging from ∼4 × 105 (Ru) to ∼2-3 × 106 (Ir, Pt). Our measurements of DPGEsul are >100 times larger than previous results but smaller than anticipated based on comparison of alloy solubilities in sulfide melts and S-free silicate melts. The presence of S in the silicate melt greatly increases alloy solubility. We use our new set of partition coefficients to develop a fully constrained model of PGE behavior during melting which accurately predicts the abundances of PGE in mantle-derived magmas and their restites, including mid-ocean ridge basalts, continental picrites, and the parental magmas of the Bushveld Complex of South Africa. Our model constrains mid-ocean ridge basalt (MORB) to be the products of pooled low and high degree fractional melts. Within-plate picrites are pooled products of larger degrees of fractional melting in columnar melting regimes. A significant control on PGE fractionation in mantle-derived magmas is exerted by residual alloy or platinum group minerals in their source. At low pressures (e.g., MORB genesis) the mantle residual to partial melting retains primitive mantle inter-element ratios and abundances of PGE until sulfide has been completely dissolved but then evolves to extremely high Pt/Pd and low Pd/Ir because Pt and Ir alloys form in the restite. During melting at high pressure to form picrites or komatiites Ir alloy appears as a restite phase but Pt alloy is not stable due to the large effect of pressure on fS2, and of temperature on fO2 along an internal

  18. Pb, Sr, and Nd isotopes in basalts and sulfides from the Juan de Fuca Ridge

    NASA Technical Reports Server (NTRS)

    Hegner, E.; Tatsumoto, M.

    1987-01-01

    Isotopic Pb, Sr, and Nd data were collected by the Alvin submersible from seven basalt glasses in the southern Juan de Fuca Ridge (JFR), giving similar ratios for Pb-206/Pb-204 of about 18.45, for Pb-207/Pb-204 of about 15.47, for Pb-208/Pb-204 of about 37.81, for Sr-87/Sr-86 of about 0.70249, and for Nd-143/Nd-144 of about 0.51315. Data suggest that the basalts are all cogenetic, and that four of the samples are also comagmatic. It is concluded that isotopic data for the JFR and seamount basalts provide additional support for the mantle blob cluster model (Allegre et al., 1984), suggesting the involvement of multiple components in the genesis of ridge basalts, and including an unusual end-member that has nonradiogenic Sr and variable Pb-206/Pb-204 isotopic compositions.

  19. Sulfide saturation history of the Stillwater Complex, Montana: chemostratigraphic variation in platinum group elements

    NASA Astrophysics Data System (ADS)

    Keays, Reid R.; Lightfoot, Peter C.; Hamlyn, Paul R.

    2012-01-01

    A platinum group element (PGE) investigation of a 5.3 km-thick stratigraphic section of the Stillwater Complex, Montana was undertaken to refine and test a geochemical technique to explore for platiniferous horizons in layered mafic/ultramafic complexes. PGE, Au, major, and trace elements were determined in 92 samples from outcrops along traverses in the Chrome Mountain and Contact Mountain areas in the western part of the Stillwater Complex where the J-M reef occurs ˜1,460 m above the floor of the intrusion. A further 29 samples from a drill hole cored in the immediate vicinity of the J-M reef were analyzed to detail compositional variations directly above and below the J-M reef. Below the J-M reef, background concentrations of Pt (10 ppb) and Pd (7 ppb) are features of peridotites with intermediate S concentrations (mostly 100-200 ppm) and rocks from the Bronzitite, Norite I, and Gabbronorite I zones (mostly <100 ppm S). A sustained increase in S abundance commences at the J-M reef and continues to increase and peaks in the center of the 600 m-thick middle banded series. Over this same interval, Pt, Pd, and Au are initially elevated and then decrease in the order Pd > Pt > Au. Within the middle and upper banded series, S abundances fluctuate considerably, but exhibit an overall upward increase. The behavior of these elements records periodic sulfide saturation during deposition of the Peridotite zone, followed by crystallization under sulfide-undersaturated conditions until saturation is achieved at the base of the J-M reef. Following formation of the reef, sulfide-saturated conditions persisted throughout the deposition of most of the remaining Lower Layered Series. This resulted in a pronounced impoverishment in PGE abundance in the remaining magma, a condition that continued throughout deposition of the remainder of a succession, which is characterized by very low Pt (1.5 ppb) and Pd (0.7 ppb) abundances. Because only unmineralized rock was selected for study

  20. Transport of Sulfide-Reduced Graphene Oxide in Saturated Quartz Sand: Cation-Dependent Retention Mechanisms.

    PubMed

    Xia, Tianjiao; Fortner, John D; Zhu, Dongqiang; Qi, Zhichong; Chen, Wei

    2015-10-01

    We describe how the reduction of graphene oxide (GO) via environmentally relevant pathways affects its transport behavior in porous media. A pair of sulfide-reduced GOs (RGOs), prepared by reducing 10 mg/L GO with 0.1 mM Na2S for 3 and 5 days, respectively, exhibited lower mobility than did parent GO in saturated quartz sand. Interestingly, decreased mobility cannot simply be attributed to the increased hydrophobicity and aggregation upon GO reduction because the retention mechanisms of RGOs were highly cation-dependent. In the presence of Na(+) (a representative monovalent cation), the main retention mechanism was deposition in the secondary energy minimum. However, in the presence of Ca(2+) (a model divalent cation), cation bridging between RGO and sand grains became the most predominant retention mechanism; this was because sulfide reduction markedly increased the amount of hydroxyl groups (a strong metal-complexing moiety) on GO. When Na(+) was the background cation, increasing pH (which increased the accumulation of large hydrated Na(+) ions on grain surface) and the presence of Suwannee River humic acid (SRHA) significantly enhanced the transport of RGO, mainly due to steric hindrance. However, pH and SRHA had little effect when Ca(2+) was the background cation because neither affected the extent of cation bridging that controlled particle retention. These findings highlight the significance of abiotic transformations on the fate and transport of GO in aqueous systems.

  1. Solubility of Csbnd Osbnd H volatiles in graphite-saturated martian basalts

    NASA Astrophysics Data System (ADS)

    Stanley, Ben D.; Hirschmann, Marc M.; Withers, Anthony C.

    2014-03-01

    To determine the speciation and concentrations of dissolved Csbnd Osbnd H volatiles in graphite-saturated martian primitive magmas, we conducted piston-cylinder experiments on graphite-encapsulated synthetic melt of Adirondack-class Humphrey basaltic composition. Experiments were performed over three orders of magnitude in oxygen fugacity (IW+2.3 to IW-0.8), and at pressures (1-3.2 GPa) and temperatures (1340-1617 °C) similar to those of possible martian source regions. Oxygen fugacities were determined from compositions of coexisting silicate melt + FePt alloy, olivine + pyroxene + FePt alloy, or melt + Fesbnd C liquid. Infrared spectra of quenched glasses all show carbonate absorptions at 1430 and 1520 cm-1, with CO2 concentrations diminishing under more reduced conditions, from 0.50 wt% down to 26 ppm. Carbon contents of silicate glasses and Fesbnd C liquids were measured using secondary ion mass spectrometry (SIMS) yielding 36-716 ppm and 6.71-7.03 wt%, respectively. Fourier transform infrared (FTIR) and SIMS analysis produced similar H2O contents of 0.26-0.85 and 0.29-0.40 wt%, respectively. Raman spectra of glasses reveal evidence for OH- ions, but no indication of methane-related species. FTIR-measured concentrations of dissolved carbonate diminish linearly with oxygen fugacity, but more reduced conditions yield greater dissolved carbonate concentrations than would be expected based on oxidized conditions in previous work. C contents of silicate glasses determined by SIMS are consistently higher than C as carbonate determined by FTIR. Their difference, termed non-carbonate C, correlates well with additional IR absorptions found in reduced glasses (f < IW+0.4) at 1615, 2205, and 3370 cm-1. These absorption bands are not seen in more oxidized glasses, except B441 (IW+1.7), presumably because they represent reduced C-bearing complexes. The 2205 cm-1 peak is attributed to a Cdbnd O complex, possibly an Fe-carbonyl ion. The 1615 cm-1 peak does not correlate with

  2. Mineralogical studies of sulfide samples and volatile concentrations of basalt glasses from the southern Juan de Fuca Ridge.

    PubMed

    Brett, R; Evans, H T; Gibson, E K; Hedenquist, J W; Wandless, M V; Sommer, M A

    1987-10-10

    Sulfide samples obtained from the U.S. Geological Survey's DSRV Alvin dives on the southern Juan de Fuca Ridge closely resemble those from the same area described by Koski et al. (1984). Major minerals include sphalerite, wurtzite, pyrite, marcasite, isocubanite, anhydrite, and chalcopyrite. Equilibrium, if attained at all, during deposition of most sulfides was a transient event over a few tens of micrometers at most and was perturbed by rapid temperature and compositional changes of the circulating fluid. Two new minerals were found: one, a hydrated Zn, Fe hydroxy-chlorosulfate, and the other, a (Mn, Mg, Fe) hydroxide or hydroxy-hydrate. Both were formed at relatively low temperatures. Lizardite, starkeyite, and anatase were found for the first time in such an environment. Sulfide geothermometry involving the system Cu-Fe-S indicates a vent temperature of <328 degrees C for one sample. Fluid inclusion studies on crystals from the same vicinity of the same sample give pressure-corrected homogenization temperatures of 268 degrees and 285 degrees C. Ice-melting temperatures on inclusions from the same sample are about -2.8 degrees C, indicating that the equivalent salinity of the trapped fluid is about 50% greater than that of seawater. Volatile concentrations from vesicle-free basalt glass from the vent field are about 0.013 wt% CO2 and 0.16 wt% H2O, CO2 contents in these samples yield an entrapment depth of 2200 m of seawater, which is the depth from which the samples were collected.

  3. Simulating Geologic Co-sequestration of Carbon Dioxide and Hydrogen Sulfide in a Basalt Formation

    SciTech Connect

    Bacon, Diana H.; Ramanathan, Ramya; Schaef, Herbert T.; McGrail, B. Peter

    2014-01-15

    Co-sequestered CO2 with H2S impurities could affect geologic storage, causing changes in pH and oxidation state that affect mineral dissolution and precipitation reactions and the mobility of metals present in the reservoir rocks. We have developed a variable component, non-isothermal simulator, STOMP-COMP (Water, Multiple Components, Salt and Energy), which simulates multiphase flow gas mixtures in deep saline reservoirs, and the resulting reactions with reservoir minerals. We use this simulator to model the co-injection of CO2 and H2S into brecciated basalt flow top. A 1000 metric ton injection of these supercritical fluids, with 99% CO2 and 1% H2S, is sequestered rapidly by solubility and mineral trapping. CO2 is trapped mainly as calcite within a few decades and H2S is trapped as pyrite within several years.

  4. Sulfur isotope budget (32S, 33S, 34S and 36S) in Pacific-Antarctic ridge basalts: A record of mantle source heterogeneity and hydrothermal sulfide assimilation

    NASA Astrophysics Data System (ADS)

    Labidi, J.; Cartigny, P.; Hamelin, C.; Moreira, M.; Dosso, L.

    2014-05-01

    To better address how Mid-Ocean Ridge Basalt (MORB) sulfur isotope composition can be modified by assimilation and/or by immiscible sulfide fractionation, we report sulfur (S), chlorine (Cl) and copper (Cu) abundances together with multiple sulfur isotope composition for 38 fresh basaltic glasses collected on the Pacific-Antarctic ridge. All the studied glasses - with the exception of 8 off-axis samples - exhibit relatively high Cl/K, as the result of pervasive Cl-rich fluid assimilation. This sample set hence offers an opportunity to document both the upper mantle S isotope composition and the effect of hydrothermal fluids assimilation on the S isotope composition of erupted basalts along segments that are devoid of plume influence.

  5. Magmatic sulfide-rich nickel-copper deposits related to picrite and (or) tholeiitic basalt dike-sill complexes-A preliminary deposit model

    USGS Publications Warehouse

    Schulz, Klaus J.; Chandler, Val W.; Nicholson, Suzanne W.; Piatak, Nadine M.; Seal, Robert R., II; Woodruff, Laurel G.; Zientek, Michael L.

    2010-01-01

    Magmatic sulfide deposits containing nickel (Ni) and copper (Cu), with or without (?) platinum-group elements (PGEs), account for approximately 60 percent of the world's Ni production and are active exploration targets in the United States and elsewhere. On the basis of their principal metal production, magmatic sulfide deposits in mafic rocks can be divided into two major types: those that are sulfide-rich, typically with 10 to 90 percent sulfide minerals, and have economic value primarily because of their Ni and Cu contents; and those that are sulfide-poor, typically with 0.5 to 5 percent sulfide minerals, and are exploited principally for PGE. Because the purpose of this deposit model is to facilitate the assessment for undiscovered, potentially economic magmatic Ni-Cu?PGE sulfide deposits in the United States, it addresses only those deposits of economic significance that are likely to occur in the United States on the basis of known geology. Thus, this model focuses on deposits hosted by small- to medium-sized mafic and (or) ultramafic dikes and sills that are related to picrite and tholeiitic basalt magmatic systems generally emplaced in continental settings as a component of large igneous provinces (LIPs). World-class examples (those containing greater than 1 million tons Ni) of this deposit type include deposits at Noril'sk-Talnakh (Russia), Jinchuan (China), Pechenga (Russia), Voisey's Bay (Canada), and Kabanga (Tanzania). In the United States, this deposit type is represented by the Eagle deposit in northern Michigan, currently under development by Kennecott Minerals.

  6. Lead isotopic compositions in olivine-hosted melt inclusions from HIMU basalts and possible link to sulfide components

    NASA Astrophysics Data System (ADS)

    Yurimoto, Hisayoshi; Kogiso, Tetsu; Abe, Kanshi; Barsczus, Hans G.; Utsunomiya, Atsushi; Maruyama, Shigenori

    2004-08-01

    Pb isotopic compositions of melt inclusions in olivine phenocrysts of lava samples from Mangaia and Rarotonga, Cook-Austral islands, have been determined by secondary ion mass spectrometry. The Pb isotopic compositions of melt inclusions from Rarotonga are consistent with those of bulk rock. On the other hand, Pb isotopic compositions of sulfide-free melt inclusions from Mangaia Island are widely distributed along the join between HIMU (i.e. highly radiogenic Pb) and less radiogenic components. The variation is much wider than that in bulk-rock samples that are invariably end-member HIMU values. In contrast, Pb isotopic compositions of sulfide and carbonate inclusions are restricted to HIMU end-member values. The variations in Pb isotopic ratios can be explained by mixing between the HIMU component and another component with less radiogenic Pb, and suggests that the HIMU component is enriched in sulfide and carbonate phases as well as Pb compared with the less radiogenic component. It seems paradoxical that a sulfide-rich component is associated with highly radiogenic Pb, because sulfides generally have extremely low U/Pb and Th/Pb ratios, which result in quite unradiogenic Pb. Subducted oceanic crust is not a likely source for such a sulfide-rich component because sulfides in subducted crust may not survive dehydration processes in subduction zones, although it can produce highly radiogenic Pb. The association of highly radiogenic Pb and sulfides implies that sulfides and radiogenic Pb in the HIMU source originate from distinct reservoirs. A possible origin of the sulfides is the Earth's core, because the core is the largest sulfur budget in the Earth. The highly radiogenic Pb may originate from subducted oceanic crust which resides at the core-mantle boundary. Alternative source for radiogenic Pb is Ca-perovskite in the lower mantle, which is the main host of incompatible elements in the lower mantle and has high U/Pb and Th/Pb ratios. The core-derived sulfides

  7. Carbonate Mineralization of Volcanic Province Basalts

    SciTech Connect

    Schaef, Herbert T.; McGrail, B. Peter; Owen, Antionette T.

    2010-03-31

    precipitates suggest changes in fluid chemistry unique to the dissolution behavior of each basalt sample reacted with CO2-saturated water. The Karoo basalt from South Africa appeared the least reactive, with very limited mineralization occurring during the testing with CO2-saturated water. The relative reactivity of different basalt samples were unexpectedly different in the experiments conducted using aqueous dissolved CO2-H2S mixtures versus those reacted with aqueous dissolved CO2 mixtures. For example, the Karoo basalt was highly reactive in the presence of aqueous dissolved CO2-H2S, as evident by small nodules of carbonate coating the basalt grains after 181 days of testing. However the most reactive basalt in CO2-H2O, Newark Basin, formed limited amounts of carbonate precipitates in the presence of aqueous dissolved CO2-H2S mixture. Basalt reactivity in CO2-H2O mixtures appears to be controlled by the composition of the glassy mesostasis, which is the most reactive component in the basalt rock. With the addition of H2S to the CO2-H2O system, basalt reactivity appears to be controlled by precipitation of coatings of insoluble Fe sulfides.

  8. Mineralogical studies of sulfide samples and volatile concentrations of basalt glasses from the southern Juan de Fuca Ridge.

    USGS Publications Warehouse

    Brett, R.; Evans, H.T.; Gibson, E.K.; Hedenquist, J.W.; Wandless, M.-V.; Sommer, M.A.

    1987-01-01

    Specifically considers unusual minerals and geothermometric relations not previously covered. Equilibrium, if attained at all, during deposition of most sulfides was a transient event over a few tens of micrometers at most and was perturbed by rapid temperature and compositional changes of the circulating fluid. Two new minerals were found: one, a hydrated Zn, Fe hydroxy-chlorosulfate, and the other, a (Mn, Mg, Fe) hydroxide or hydroxy-hydrate. Both were formed at relatively low temperatures. Lizardite, starkeyite, and anatase were found for the first time in such an environment.-from Authors

  9. S saturation history of Nain Plutonic Suite mafic intrusions: origin of the Voisey's Bay Ni-Cu-Co sulfide deposit, Labrador, Canada

    NASA Astrophysics Data System (ADS)

    Lightfoot, Peter C.; Keays, Reid R.; Evans-Lamswood, Dawn; Wheeler, Robert

    2012-01-01

    ores have higher Ni and Pd tenor than the Eastern Deeps massive sulfides; this is consistent with both a higher R factor and greater degree of silicate parental magma evolution in the Ovoid than the Eastern Deeps. The disseminated sulfides surrounding the Eastern Deeps deposit have some of the highest Ni and Pd tenors at Voisey's Bay, which are indicative of not only more primitive magmas but also higher R factors than the Ovoid or the Eastern Deeps. VTT and normal-textured troctolite of the Eastern Deeps that contain trace sulfide have 0.1-3 ppb Pt and 0.1-3 ppb Pd, whereas weakly to heavily mineralized variable troctolites in the same unit have one to two orders of magnitude higher abundances of Pt and Pd. Troctolites and olivine gabbros from other parts of the Voisey's Bay Intrusion and other Nain Plutonic Suite Intrusions, including the Kiglapait, Newark Bay, Barth Island, Mushua, and Nain Bay South Intrusion, also have low platinum group element abundances. Although it is possible that this is a signature of a widespread sulfide saturation event that pre-dated ore formation at Voisey's Bay, it is more likely that platinum group element (PGE) depletion is a product of the source melting process where low degrees of melting resulted in the retention of PGE in the mantle source. If so, this indicates that PGE depletion should be used with caution as an exploration tool in the Nain Plutonic Suite.

  10. Aqueous Iron-Sulfide Clusters in Variably Saturated Soil Systems: Implications for Iron Cycling and Fluid Flow

    NASA Astrophysics Data System (ADS)

    McGuire, J. T.; Hansen, D. J.; Mohanty, B. P.

    2008-12-01

    Iron and sulfur cycling is an important control on contaminant fate and transport, the availability of micronutrients and the physics of water flow. This study explores the effects of soil structure (i.e. layers, lenses, macropores, or fractures) on linked biogeochemical and hydrological processes involving Fe and S cycling in the vadose zone using packed soil columns. Three laboratory soil columns were constructed: a homogenized medium-grained sand, homogenized organic-rich loam, and a sand-over-loam layered column. Both upward and downward infiltration of water was evaluated during experiments to simulate rising water table and rainfall events respectively. Water samples extracted by lysimeter were analyzed for reduced species (including total sulfide, Fe(II), and FeSaq) voltammetrically using a mercury drop electrode. In addition to other reduced species, aqueous FeS clusters (FeSaq) were observed in two of the columns, with the greatest concentrations of FeSaq occurring in close proximity to the soil interface in the layered column. To our knowledge, this is the first documentation of aqueous FeS clusters in partially saturated sediments. The aqueous nature of FeSaq allows it to be transported instead of precipitating and suggests that current conceptual models of iron-sulfur cycling may need to be adapted to account for an aqueous phase. The presence of iron-rich soil aggregates near the soil interface may indicate that FeS clusters played a critical role in the formation of soil aggregates that subsequently caused up to an order of magnitude decrease in hydraulic conductivity.

  11. Triggers on sulfide saturation in Fe-Ti oxide-bearing, mafic-ultramafic layered intrusions in the Tarim large igneous province, NW China

    NASA Astrophysics Data System (ADS)

    Cao, Jun; Wang, Christina Yan; Xu, Yi-Gang; Xing, Chang-Ming; Ren, Ming-Hao

    2016-08-01

    Three Fe-Ti oxide-bearing layered intrusions (Mazaertag, Wajilitag, and Piqiang) in the Tarim large igneous province (NW China) have been investigated for understanding the relationship of sulfide saturation, Platinum-group element (PGE) enrichment, and Fe-Ti oxide accumulation in layered intrusions. These mafic-ultramafic layered intrusions have low PGE concentrations (<0.4 ppb Os, <0.7 ppb Ir, <1 ppb Ru, <0.2 ppb Rh, <5 ppb Pt, and <8 ppb Pd) and elevated Cu/Pd (2.2 × 104 to 3.3 × 106). The low PGE concentrations of the rocks are mainly attributed to PGE-depleted, parental magma that was produced by low degrees of partial melting of the mantle. The least contaminated rocks of the Mazaertag and Wajilitag intrusions have slightly enriched Os isotopic compositions with γOs(t = 280 Ma) values ranging from +13 to +23, indicating that the primitive magma may have been generated from a convecting mantle, without appreciable input of lithospheric mantle. The Mazaertag and Wajilitag intrusions have near-chondritic γOs(t) values (+13 to +60) against restricted ɛ Nd(t) values (-0.4 to +2.8), indicating insignificant crustal contamination. Rocks of the Piqiang intrusion have relatively low ɛ Nd(t) values of -3.1 to +1.0, consistent with ˜15 to 25 % assimilation of the upper crust. The rocks of the Mazaertag and Wajilitag intrusions have positive correlation of PGE and S, pointing to the control of PGE by sulfide. Poor correlation of PGE and S for the Piqiang intrusion is attributed to the involvement of multiple sulfide-stage liquids with different PGE compositions or sulfide-oxide reequilibration on cooling. These three layered intrusions have little potential of reef-type PGE mineralization. Four criteria are summarized in this study to help discriminate between PGE-mineralized and PGE-unmineralized mafic-ultramafic intrusions.

  12. Using chalcophile elements to constrain crustal contamination and xenolith-magma interaction in Cenozoic basalts of eastern China

    NASA Astrophysics Data System (ADS)

    Zeng, Gang; Huang, Xiao-Wen; Zhou, Mei-Fu; Chen, Li-Hui; Xu, Xi-Sheng

    2016-08-01

    Continental basalts have complicated petrogenetic processes, and their chemical compositions can be affected by multi-staged geological evolution. Compared to lithophile elements, chalcophile elements including Ni, platinum-group elements (PGEs) and Cu are sensitive to sulfide segregation and fractional crystallization during the evolution of mantle-derived magmas and can provide constraints on the genesis of continental basalts. Cenozoic intra-continental alkaline basalts in the Nanjing basaltic field, eastern China, include high-Ca and low-Ca varieties. All these basalts have poor PGE contents with Ir ranging from 0.016 ppb to 0.288 ppb and high Cu/Pd ratios from 0.7 × 105 to 4.7 × 105 (5.7 × 103 for DMM), indicating that they were derived from sulfide-saturated mantle sources with variable amounts of residual sulfide during melting or might undergo an early-sulfide segregation in the mantle. Relatively high Cu/Pd ratios along with high Pd concentrations for the high-Ca alkaline basalts indicate an additional removal of sulfide during magma ascent. Because these basalts have high, variable Pd/Ir ratios (2.8-16.8) with low Ce/Pb (9.9-19.7) ratios and εNd values (+ 3.6-+6.4), crustal contamination is proposed to be a potential process to induce the sulfide saturation and removal. Significantly increased Pd/Ir ratios for few high-Ca basalts can be explained by the fractionation of laurite or Ru-Os-Ir alloys with olivine or chromite. For low-Ca alkaline basalts, their PGE contents are well correlated with the MgO, Sc contents, incompatible element ratios (Lu/Hf, Na/Ti and Ca/Al) and Hf isotopes. Good correlations are also observed between Pd/Ir (or Rh/Ir) and Na/Ti (or Ca/Al) ratios. Variations of these elemental ratios and Hf isotopes is previously documented to be induced by the mixing of peridotite xenolith-released melts during ascent. Therefore, we suggest that such xenolith-magma interaction are also responsible for the variable PGE compositions of low

  13. Geochemistry of the Kalatongke Ni-Cu-(PGE) sulfide deposit, NW China: implications for the formation of magmatic sulfide mineralization in a postcollisional environment

    NASA Astrophysics Data System (ADS)

    Song, Xie-Yan; Li, Xiang-Ren

    2009-04-01

    The Kalatongke (also spelt as Karatungk) Ni-Cu-(platinum-group element, PGE) sulfide deposit, containing 33 Mt sulfide ore with a grade of 0.8 wt.% Ni and 1.3 wt.% Cu, is located in the Eastern Junggar terrane, Northern Xinjiang, NW China. The largest sulfide ore body, which occupies more than 50 vol.% of the intrusion Y1, is dominantly comprised of disseminated sulfide with a massive sulfide inner zone. Economic disseminated sulfides also occur at the base of the intrusions Y2 and Y3. The main host rock types are norite in the lower part and diorite in the upper part of each intrusion. Enrichment in large ion lithophile elements and depletion in heavy rare earth elements relative to mid-ocean ridge basalt indicate that the mafic intrusions were produced from magmas derived from a metasomatized garnet lherzolite mantle. The average grades of the disseminated ores are 0.6 wt.% Ni and 1.1 wt.% Cu, whereas those of the massive ores are 2 wt.% Ni and 8 wt.% Cu. The PGE contents of the disseminated ores (14-69 ppb Pt and 78-162 ppb Pd) are lower than those of the massive ores (120-505 ppb Pt and 30-827 ppb Pd). However, on the basis of 100% sulfide, PGE contents of the massive sulfides are lower than those of the disseminated sulfides. Very high Cu/Pd ratios (>4.5 × 104) indicate that the Kalatongke sulfides segregated from PGE-depleted magma produced by prior sulfide saturation and separation. A negative correlation between the Cu/Pd ratio and the Pd content in 100% sulfide indicates that the PGE content of the sulfide is controlled by both the PGE concentrations in the parental silicate magma and the ratio of the amount of silicate to sulfide magma. The negative correlations between Ir and Pd indicate that the massive sulfides experienced fractionation.

  14. Generation of Sulfur-rich, Sulfur-undersaturated Basaltic Melts in Oxidized Arc Sources.

    NASA Astrophysics Data System (ADS)

    Jugo, P. J.; Luth, R. W.; Richards, J. P.

    2003-12-01

    Although sulfur is a minor element in the Earth, it has a disproportionate impact because it commonly occurs as sulfide. Sulfides largely control the behavior of chalcophile (e.g., Cu, Ni) and highly siderophile elements (Ru, Rh, Pd, Re, Os, Ir, Pt, and Au) that are of interest because either they are economically important or because they provide valuable information about geochemical processes. Island arc basalts are more oxidized than basalts from other tectonic settings and therefore, in these settings, sulfur maybe present not as sulfide but as sulfate. In addition to the impact on the behavior of chalcophile and siderophile elements, sulfur speciation as sulfate may have a role on the occurrence of sulfur-rich explosive volcanism, which has been linked to significant short-term variations in global climate. However, little is known about the range in oxygen fugacity for the transition from solubility as sulfide to solubility as sulfate. We used experimental data on the solubility of sulfur in basaltic melts saturated with either sulfide or sulfate at different oxygen fugacities to model this transition. Our model shows that the ten-fold increase in the solubility of sulfur (from 0.14 wt.% to 1.5 wt.%) observed experimentally occurs at oxygen fugacities between ˜FMQ+1 and ˜FMQ+2, conditions under which many arc magmas are thought to be generated. The increase in the solubility of sulfur with increasing oxygen fugacity implies that in oxidized arc sources very low degrees of partial melting are sufficient to generate basaltic melts that are simultaneously sulfur-rich and sulfur-undersaturated. In the absence of sulfides, oxides and metallic alloys may influence the behavior of some (but not all) the highly siderophile elements whereas the chalcophile and some siderophile elements become incompatible. As a consequence, melting of oxidized sources in which sulfides are not stable would favor incorporation of metals such as Cu, Ni, Au and Pd in the melts and

  15. Magmatic Cu-Ni sulfide mineralization of the Huangshannan mafic-untramafic intrusion, Eastern Tianshan, China

    NASA Astrophysics Data System (ADS)

    Zhao, Yun; Xue, Chunji; Zhao, Xiaobo; Yang, YongQiang; Ke, Junjun

    2015-06-01

    The Huangshannan Ni-Cu (-PGE) sulfide deposit, a new discovery from geological prospecting in Eastern Tianshan, is in a belt of magmatic Ni-Cu (-PGE) sulfide deposits along the southern margin of the Central Asian Orogenic Belt. The host intrusion of the Huangshannan deposit is composed of a layered ultramafic sequence and a massive gabbro-diorite unit. The major sulfide orebodies occur mainly within websterite and lherzolite in the layered ultramafic sequence. In-situ zircon U-Pb dating analyses yielded a crystallization age of 282.5 ± 1.4 Ma, similar to the ages of the Permian Tarim mantle plume. Samples from the Huangshannan intrusion are characterized by nearly flat rare earth elements patterns, negative Zr, Ti and Nb anomalies, arc-like Th/Yb and Nb/Yb ratios, and significantly lower rare earth element and immobile trace element contents than the Tarim basalts. These characteristics suggest that the Huangshannan intrusion was not generated from the Tarim mantle plume. The primary magma for the Huangshannan intrusion and its associated sulfide mineralization were formed from different pulses of picritic magma with different degrees of crustal contamination. The first pulse underwent an initial removal of 0.016% sulfide in the deep magma chamber. The evolved magma reached sulfide saturation again in the shallow magma chamber and formed sulfide ores in lherzolite. The second pulse of magma reached a level of 0.022% sulfide segregation at staging chamber before ascending up to the shallow magma chamber. In the shallow conduit system, this sulfide-unsaturated magma mixed with the first pulse of magma and with contamination from the country rocks, leading to the formation of sulfide ores in websterite. The third magma pulse from the deep chamber formed the unmineralized massive gabbro-diorite unit of the Huangshannan intrusion.

  16. Sulfur K-edge XANES analysis of natural and synthetic basaltic glasses: Implications for S speciation and S content as function of oxygen fugacity

    NASA Astrophysics Data System (ADS)

    Jugo, Pedro J.; Wilke, Max; Botcharnikov, Roman E.

    2010-05-01

    XANES analyses at the sulfur K-edge were used to determine the oxidation state of S in natural and synthetic basaltic glasses and to constrain the fO2 conditions for the transition from sulfide (S2-) to sulfate (S6+) in silicate melts. XANES spectra of basaltic samples from the Galapagos spreading center, the Juan de Fuca ridge and the Lau Basin showed a dominant broad peak at 2476.8 eV, similar to the spectra obtained from synthetic sulfide-saturated basalts and pyrrhotite. An additional sharp peak at 2469.8 eV, similar to that of crystalline sulfides, was present in synthetic glasses quenched from hydrous melts but absent in anhydrous glasses and may indicate differences in sulfide species with hydration or presence of minute sulfide inclusions exsolved during quenching. The XANES spectra of a basalt from the 1991 eruption of Mount Pinatubo, Philippines, and absarokitic basalts from the Cascades Range, Oregon, U.S.A., showed a sharp peak at 2482.8 eV, characteristic of synthetic sulfate-saturated basaltic glasses and crystalline sulfate-bearing minerals such as haüyne. Basaltic samples from the Lamont Seamount, the early submarine phase of Kilauea volcano and the Loihi Seamount showed unequivocal evidence of the coexistence of S2- and S6+ species, emphasizing the relevance of S6+ to these systems. XANES spectra of basaltic glasses synthesized in internally-heated pressure vessels and equilibrated at fO2 ranging from FMQ-1.7 to FMQ+2.7 showed systematic changes in the features related to S2- and S6+ with changes in fO2. No significant features related to sulfite (S4+) species were observed. These results were used to construct a function that allows estimates of S6+/ΣS from XANES data. Theoretical considerations and comparison of compiled S6+/ΣS data obtained by SKα shifts estimated with electron probe microanalysis (EPMA) and S6+/ΣS obtained from XANES spectra show that data obtained from EPMA measurements underestimate S6+/ΣS in samples that are sulfate

  17. Sulfur K-edge XANES analysis of natural and synthetic basaltic glasses: Implications for S speciation and S content as function of oxygen fugacity

    NASA Astrophysics Data System (ADS)

    Jugo, Pedro J.; Wilke, Max; Botcharnikov, Roman E.

    2010-10-01

    XANES analyses at the sulfur K-edge were used to determine the oxidation state of S species in natural and synthetic basaltic glasses and to constrain the fO 2 conditions for the transition from sulfide (S 2-) to sulfate (S 6+) in silicate melts. XANES spectra of basaltic samples from the Galapagos spreading center, the Juan de Fuca ridge and the Lau Basin showed a dominant broad peak at 2476.8 eV, similar to the spectra obtained from synthetic sulfide-saturated basalts and pyrrhotite. An additional sharp peak at 2469.8 eV, similar to that of crystalline sulfides, was present in synthetic glasses quenched from hydrous melts but absent in anhydrous glasses and may indicate differences in sulfide species with hydration or presence of minute sulfide inclusions exsolved during quenching. The XANES spectra of a basalt from the 1991 eruption of Mount Pinatubo, Philippines, and absarokitic basalts from the Cascades Range, Oregon, USA, showed a sharp peak at 2482.8 eV, characteristic of synthetic sulfate-saturated basaltic glasses and crystalline sulfate-bearing minerals such as hauyne. Basaltic samples from the Lamont Seamount, the early submarine phase of Kilauea volcano and the Loihi Seamount showed unequivocal evidence of the coexistence of S 2- and S 6+ species, emphasizing the relevance of S 6+ to these systems. XANES spectra of basaltic glasses synthesized in internally-heated pressure vessels and equilibrated at fO 2 ranging from FMQ - 1.4 to FMQ + 2.7 showed systematic changes in the features related to S 2- and S 6+ with changes in fO 2. No significant features related to sulfite (S 4+) species were observed. These results were used to construct a function that allows estimates of S 6+/ΣS from XANES data. Comparison of S 6+/ΣS data obtained by S Kα shifts measured with electron probe microanalysis (EPMA), S 6+/ΣS obtained from XANES spectra, and theoretical considerations show that data obtained from EPMA measurements underestimate S 6+/ΣS in samples that

  18. Geodynamics of magmatic Cu-Ni-PGE sulfide deposits: new insights from the Re-Os isotope system

    USGS Publications Warehouse

    Lambert, D.D.; Foster, J.G.; Frick, L.R.; Ripley, E.M.; Zientek, M.L.

    1998-01-01

    In this study, we reassess crustal contamination and sulfide ore-forming processes in some of the largest magmatic ore deposits, using published Re-Os isotope data and a modeling methodology that incorporates the R factor, defined as the effective mass of silicate magma with which a given mass of sulfide magma has equilibrated, in an Re-Os isotope mixing equation. We show that there is less disparity between conclusions based on Re-Os isotope data compared to other isotopic systems if the R factor is considered, Komatiite-associated Ni sulfide ore systems typically have high Os concentrations, low Re/Os ratios, and near-chondritic initial Os isotope compositions. For magmatic sulfide ores that are interpreted to have experienced relatively low R factors (2,000). Sulfide saturation in these ore systems may, therefore, have been achieved via changes in intensive parameters of the komatiite lavas (cooling or decompression) or changes in compositional parameters transparent to the Re-Os isotope system (e.g., fo2/fs2/fH2O)- Basalt-gabbro-associated Cu-Ni sulfide ore systems at Duluth, Sudbury, and Stillwater are quite distinct from those at Kambalda by having comparatively low Os concentrations, high Re/Os ratios, and high initial Os isotope compositions, These chemical and isotopic characteristics are indicative of significant interactions between their parental basaltic magmas and old crust because there are no known mantle reservoirs with such extreme geocheinical characteristics. Our modeling suggests that for Cu-Ni sulfide ores at Duluth, Sudbury, and Stillwater to maintain the observed high initial Os isotope compositions inherited from a crustal contaminant, R factors for these systems must have been low (< 10,000), consistent with their low metal concentrations. Thus, we interpret this style of base metal sulfide mineralization to be derived from crustally contaminated but less dynamic magmatic systems that did not permit extensive equilibration of sulfide magma

  19. Reduction of mare basalts by sulfur loss

    USGS Publications Warehouse

    Brett, R.

    1976-01-01

    Metallic Fe content and S abundance are inversely correlated in mare basalts. Either S volatilization from the melt results in reduction of Fe2+ to Fe0 or else high S content decreases Fe0 activity in the melt, thus explaining the correlation. All considerations favor the model that metallic iron in mare basalts is due to sulfur loss. The Apollo 11 and 17 mare basalt melts were probably saturated with S at the time of eruption; the Apollo 12 and 15 basalts were probably not saturated. Non-mare rocks show a positive correlation of S abundance with metallic Fe content; it is proposed that this is due to the addition of meteoritic material having a fairly constant Fe0/S ratio. If true, metallic Fe content or S abundance in non-mare rocks provides a measure of degree of meteoritic contamination. ?? 1976.

  20. The significance of PGE variations with Sr-Nd isotopes and lithophile elements in the Emeishan flood basalt province from SW China to northern Vietnam

    NASA Astrophysics Data System (ADS)

    Li, Chusi; Ripley, Edward M.; Tao, Yan; Hu, Ruizhong

    2016-04-01

    New analyses of siderophile-lithophile elements and Sr-Nd isotopes in the Permian basalts and picrites from northern Vietnam, the southernmost occurrence of the Emeishan flood basalt province, together with previously published data, are used to address the question of whether any meaningful correlation between these elements and isotopes exists at a province scale. The available data show that negative correlations between εNd, (87Sr/86Sr)i and mantle-normalized (Nb/Th)n are present in the basalts but not in the associated picrites. This indicates that crustal contamination is negligible in the picrites but significant in some of the basalts. The picrites and basalts from the entire province show negative correlations between (Rh/Ru)n, (Pt/Ru)n, (Pd/Ru)n and Mg-number. This indicates that Ru behaves compatibly whereas Rh, Pt and Pd behave incompatibly during magma differentiation. The incompatible behavior of Rh in natural basaltic systems is also supported by the fact that (Pt/Rh)n remains constant with decreasing Mg-number in the lavas. Depletions of Pd and Pt, and to a lesser degree Cu, in some basaltic samples characterized by relatively low εNd and (Nb/Th)n support the notion that sulfide saturation in the magmas was triggered by a combination of siliceous crustal contamination and addition of external sulfur. Within the entire flood basalt province only the picrites from Song Da, northern Vietnam show clear depletion in Ir relative to Ru. These picrites are also characterized higher Al2O3/TiO2 and lower mantle-normalized La/Yb (0.2-2.4) than those from elsewhere in the province, possibly due to the involvement of an Ir-depleted, fertile mantle component in magma generation at this location.

  1. Concentrations and isotope ratios of carbon, nitrogen and sulfur in ocean-floor basalts

    NASA Technical Reports Server (NTRS)

    Sakai, H.; Ueda, A.; Des Marais, D. J.; Moore, J. G.

    1984-01-01

    Ocean floor basalts studied from the Galapagos Ridge, FAMOUS area, Cayman Trough and Kilauea east rift contain 20-200 ppm carbon and 0.3-2.8 ppn nitrogen as sums of the vesicle-filling gases CO2 and N2 and dissolved species. The wide range of carbon contents found is due partly to the different extent of outgassing of vesicle-filling gases and partly to depth dependency of dissolved CO2 in the basalts. Sulfate commonly exists with sulfide in these basalts, and the sulfate/sulfide ratio increases with increasing water content, perhaps reflecting the higher oxidation potential in basalt melt of the higher water content.

  2. Bubble Growth in Lunar Basalts

    NASA Astrophysics Data System (ADS)

    Zhang, Y.

    2009-05-01

    Although Moon is usually said to be volatile-"free", lunar basalts are often vesicular with mm-size bubbles. The vesicular nature of the lunar basalts suggests that they contained some initial gas concentration. A recent publication estimated volatile concentrations in lunar basalts (Saal et al. 2008). This report investigates bubble growth on Moon and compares with that on Earth. Under conditions relevant to lunar basalts, bubble growth in a finite melt shell (i.e., growth of multiple regularly-spaced bubbles) is calculated following Proussevitch and Sahagian (1998) and Liu and Zhang (2000). Initial H2O content of 700 ppm (Saal et al. 2008) or lower is used and the effect of other volatiles (such as carbon dioxide, halogens, and sulfur) is ignored. H2O solubility at low pressures (Liu et al. 2005), concentration-dependent diffusivity in basalt (Zhang and Stolper 1991), and lunar basalt viscosity (Murase and McBirney 1970) are used. Because lunar atmospheric pressure is essentially zero, the confining pressure on bubbles is completely supplied by the overlying magma. Due to low H2O content in lunar basaltic melt (700 ppm H2O corresponds to a saturation pressure of 75 kPa), H2O bubbles only grow in the upper 16 m of a basalt flow or lake. A depth of 20 mm corresponds to a confining pressure of 100 Pa. Hence, vesicular lunar rocks come from very shallow depth. Some findings from the modeling are as follows. (a) Due to low confining pressure as well as low viscosity, even though volatile concentration is very low, bubble growth rate is extremely high, much higher than typical bubble growth rates in terrestrial melts. Hence, mm-size bubbles in lunar basalts are not strange. (b) Because the pertinent pressures are so low, bubble pressure due to surface tension plays a main role in lunar bubble growth, contrary to terrestrial cases. (c) Time scale to reach equilibrium bubble size increases as the confining pressure increases. References: (1) Liu Y, Zhang YX (2000) Earth

  3. Enhanced Mantle Conductivity from Sulfides beneath the Sierra Nevada?

    NASA Astrophysics Data System (ADS)

    Park, S. K.

    2002-12-01

    A region of enhanced mantle conductivity (0.03-0.1 S/m) beneath the southern Sierra Nevada, where elevations of over 4000 m are found, has been attributed previously to 3-5% basaltic melt (Park et al., 1996) and to a mix of basaltic and sulfide melt (Ducea and Park, 2000). Because the sulfide melt is assumed to have similar conductivities to its solid counterpart (10,000 S/m), very small amounts (< 0.1%) of sulfide are needed in order to reduce the bulk conductivity from matrix values of about 0.003 S/m or even that of the matrix-basalt melt mix to the values observed. Basaltic melt percentages of less than 1% are needed in the presence of ~0.1% sulfide melt in order to match the observed mantle values. Xenoliths from the Holocene basalts in the Big Pine Volcanic Field contain 0.06-0.4% sulfide, so the estimated values are reasonable. Given the lack of evidence for volumetrically extensive, young (< 10 Ma) basaltic volcanism, calculated residence times of approximately 100 Ka for 3-5% partial melt, the short (about 300 Ka) times needed to develop connected pathways for the basalt, and the young extension of the adjacent Basin and Range province, a mixed melt with both basalt and sulfides seems more reasonable. This conclusion presupposes that the sulfide melt is somehow interconnected in the mantle. Models in which the matrix, the basaltic melt, and the sulfide melt each form interconnected, interlaced networks leads to much higher predictions of mantle conductivity; the sulfide melt fraction must be discontinuous in order to lower bulk conductivity. Petrological studies of sulfide-silicate systems confirm this conclusion; sulfide melts form isolated blebs on the surfaces of olivine within interconnected basaltic melt channels (Holzheid et al., 2000). Simple series-parallel models of ~1% continuous basaltic melt and ~0.01% discontinuous sulfide melt provide bulk conductivities comparable to the observed mantle values. More complicated equivalent media and Hashin

  4. Petrogenesis of the Ni-Cu-PGE sulfide-bearing Tamarack Intrusive Complex, Midcontinent Rift System, Minnesota

    NASA Astrophysics Data System (ADS)

    Taranovic, Valentina; Ripley, Edward M.; Li, Chusi; Rossell, Dean

    2015-01-01

    MRS, and are indicative of significant crustal contamination. Differences in textures, whole-rock and mineral compositions, and sulfide distribution are consistent with the emplacement of at least two distinct sulfide saturated magmatic pulses. Ni-enrichment in the TIC indicates that sulfide saturation was attained prior to the sequestration of major proportions of Ni by olivine, possibly at a deeper chamber in the magmatic system. The addition of crustal S from the Thomson Formation sulfidic country rocks is thought to have been the principal process which drove the early attainment of sulfide saturation in the magmas. The CGO Intrusion carried the greater abundance of sulfide liquid, but both the CGO and FGO intrusive sequences represent the accumulation of dense silicate minerals and sulfide liquid in a conduit system. The genetic processes that were operative in the formation of Ni-Cu-PGE mineralization in the Tamarack Intrusive Complex appear to be typical of conduit-style magmatic sulfide deposits associated with large continental basaltic provinces.

  5. Continental Flood Basalts

    NASA Astrophysics Data System (ADS)

    Continental flood basalts have been receiving considerable scientific attention lately. Recent publications have focused on several particular flood-basalt provinces (Brito-Arctic, Karoo, Parana', Deccan, and Columbia Plateau), and much attention has been given to the proposed connection between flood-basalt volcanism, bolide impacts, and mass extinctions. The editor of Continental Flood Basalts, J. D. Macdougall, conceived the book to assemble in a single volume, from a vast and scattered literature, an overview of each major post-Cambrian flood-basalt province.Continental Flood Basalts has 10 chapters; nine treat individual flood-basalt provinces, and a summary chapter compares and contrasts continental flood-basalts and mid-oceanic ridge basalts. Specifically, the chapters address the Columbia River basalt, the northwest United States including the Columbia River basalt, the Ethiopian Province, the North Atlantic Tertiary Province, the Deccan Traps, the Parana' Basin, the Karoo Province, the Siberian Platform, and Cenozoic basaltic rocks in eastern China. Each chapter is written by one or more individuals with an extensive background in the province.

  6. Selenium Sulfide

    MedlinePlus

    Selenium sulfide comes in a lotion and is usually applied as a shampoo. As a shampoo, selenium sulfide usually is used twice a week for the first ... it is irritating. Rinse off all of the lotion.Do not use this medication on children younger ...

  7. The Kabanga Ni sulfide deposit, Tanzania: I. Geology, petrography, silicate rock geochemistry, and sulfur and oxygen isotopes

    NASA Astrophysics Data System (ADS)

    Maier, Wolfgang D.; Barnes, Sarah-Jane; Sarkar, Arindam; Ripley, Ed; Li, Chusi; Livesey, Tim

    2010-06-01

    The Kabanga Ni sulfide deposit represents one of the most significant Ni sulfide discoveries of the last two decades, with current indicated mineral resources of 23.23 Mt at 2.64% Ni and inferred mineral resources of 28.5 Mt at 2.7% Ni (Nov. 2008). The sulfides are hosted by a suite of ˜1.4 Ga ultramafic-mafic, sill-like, and chonolithic intrusions that form part of the approximately 500 km long Kabanga-Musongati-Kapalagulu igneous belt in Tanzania and Burundi. The igneous bodies are up to about 1 km thick and 4 km long. They crystallized from several compositionally distinct magma pulses emplaced into sulfide-bearing pelitic schists. The first magma was a siliceous high-magnesium basalt (approximately 13.3% MgO) that formed a network of fine-grained acicular-textured gabbronoritic and orthopyroxenitic sills (Mg# opx 78-88, An plag 45-88). The magma was highly enriched in incompatible trace elements (LILE, LREE) and had pronounced negative Nb and Ta anomalies and heavy O isotopic signatures (δ18O +6 to +8). These compositional features are consistent with about 20% contamination of primitive picrite with the sulfidic pelitic schists. Subsequent magma pulses were more magnesian (approximately 14-15% MgO) and less contaminated (e.g., δ18O +5.1 to +6.6). They injected into the earlier sills, resulting in the formation of medium-grained harzburgites, olivine orthopyroxenites and orthopyroxenites (Fo 83-89, Mg# opx 86-89), and magmatic breccias consisting of gabbronorite-orthopyroxenite fragments within an olivine-rich matrix. All intrusions in the Kabanga area contain abundant sulfides (pyrrhotite, pentlandite, and minor chalcopyrite and pyrite). In the lower portions and the immediate footwall of two of the intrusions, namely Kabanga North and Kabanga Main, there occur numerous layers, lenses, and veins of massive Ni sulfides reaching a thickness of several meters. The largest amount of high grade, massive sulfide occurs in the smallest intrusion (Kabanga North

  8. Sulfur and sulfides in chondrules

    NASA Astrophysics Data System (ADS)

    Marrocchi, Yves; Libourel, Guy

    2013-10-01

    The nature and distribution of sulfides within type I PO, POP and PP chondrules of the carbonaceous chondrite Vigarano (CV3) have been studied by secondary electron microscopy and electron microprobe. They occur predominantly as spheroidal blebs composed entirely of low-Ni iron sulfide (troilite, FeS) or troilite + magnetite but in less abundance in association with metallic Fe-Ni beads in opaque assemblages. Troilites are mainly located within the low-Ca pyroxene outer zone and their amounts increase with the abundance of low-Ca pyroxene within chondrules, suggesting co-crystallization of troilite and low-Ca pyroxene during high-temperature events. We show that sulfur concentration and sulfide occurrence in chondrules obey high temperature sulfur solubility and saturation laws. Depending on the fS2 and fO2 of the surrounding gas and on the melt composition, mainly the FeO content, sulfur dissolved in chondrule melts may eventually reach a concentration limit, the sulfur content at sulfide saturation (SCSS), at which an immiscible iron sulfide liquid separates from the silicate melt. The occurrence of both a silicate melt and an immiscible iron sulfide liquid is further supported by the non-wetting behavior of sulfides on silicate phases in chondrules due to the high interfacial tension between their precursor iron-sulfide liquid droplets and the surrounding silicate melt during the high temperature chondrule-forming event. The evolution of chondrule melts from PO to PP towards more silicic compositions, very likely due to high PSiO(g) of the surrounding nebular gas, induces saturation of FeS at much lower S content in PP than in PO chondrules, leading to the co-crystallization of iron sulfides and low-Ca pyroxenes. Conditions of co-saturation of low-Ca pyroxene and FeS are only achieved in non canonical environments characterized by high partial pressures of sulfur and SiO and redox conditions more oxidizing than IW-3. Fe and S mass balance calculations also

  9. The biological consequences of flood basalt volcanism

    NASA Astrophysics Data System (ADS)

    Clapham, M.

    2012-12-01

    Flood basalt eruptions are among the largest environmental perturbations of the Phanerozoic. The rapid release of CO2 from a large igneous province would have triggered a chain of events that can include climate warming, ocean acidification, reduced seawater carbonate saturation, and expanded oceanic anoxia. Those stressors have widely negative impacts on marine organisms, especially on calcified taxa, by affecting their respiratory physiology and reducing energy available for growth and reproduction. Many Phanerozoic extinctions, most notably the end-Permian and end-Triassic mass extinctions, coincided with flood basalt eruptions and shared distinctive patterns of taxonomic and ecological selectivity. In these extinctions, highly active organisms were more likely to survive because they possess physiological adaptations for maintaining internal pH during activity, which also proves useful when buffering pH against ocean acidification. In contrast, species that did not move and had low metabolic rates, such as brachiopods and sponges, suffered considerable losses during these extinctions. Heavily-calcified organisms, especially corals, were particularly vulnerable; as a result, ocean acidification and saturation state changes from flood basalt eruptions often triggered crises in reef ecosystems. This characteristic pattern of selectivity during "physiological" extinctions that closely coincided with flood basalts provides a template for assessing the causes of other extinction events. Because these crises also provide deep time analogues for the ongoing anthropogenic crisis of warming, ocean acidification, and expanded anoxia, the selectivity patterns can also help constrain "winners" and "losers" over upcoming decades.

  10. Linking geology, fluid chemistry, and microbial activity of basalt- and ultramafic-hosted deep-sea hydrothermal vent environments.

    PubMed

    Perner, M; Hansen, M; Seifert, R; Strauss, H; Koschinsky, A; Petersen, S

    2013-07-01

    Hydrothermal fluids passing through basaltic rocks along mid-ocean ridges are known to be enriched in sulfide, while those circulating through ultramafic mantle rocks are typically elevated in hydrogen. Therefore, it has been estimated that the maximum energy in basalt-hosted systems is available through sulfide oxidation and in ultramafic-hosted systems through hydrogen oxidation. Furthermore, thermodynamic models suggest that the greatest biomass potential arises from sulfide oxidation in basalt-hosted and from hydrogen oxidation in ultramafic-hosted systems. We tested these predictions by measuring biological sulfide and hydrogen removal and subsequent autotrophic CO2 fixation in chemically distinct hydrothermal fluids from basalt-hosted and ultramafic-hosted vents. We found a large potential of microbial hydrogen oxidation in naturally hydrogen-rich (ultramafic-hosted) but also in naturally hydrogen-poor (basalt-hosted) hydrothermal fluids. Moreover, hydrogen oxidation-based primary production proved to be highly attractive under our incubation conditions regardless whether hydrothermal fluids from ultramafic-hosted or basalt-hosted sites were used. Site-specific hydrogen and sulfide availability alone did not appear to determine whether hydrogen or sulfide oxidation provides the energy for primary production by the free-living microbes in the tested hydrothermal fluids. This suggests that more complex features (e.g., a combination of oxygen, temperature, biological interactions) may play a role for determining which energy source is preferably used in chemically distinct hydrothermal vent biotopes.

  11. Chemistry and isotope ratios of sulfur in basalts and volcanic gases at Kilauea volcano, Hawaii

    USGS Publications Warehouse

    Sakai, H.; Casadevall, T.J.; Moore, J.G.

    1982-01-01

    Eighteen basalts and some volcanic gases from the submarine and subaerial parts of Kilauea volcano were analyzed for the concentration and isotope ratios of sulfur. By means of a newly developed technique, sulfide and sulfate sulfur in the basalts were separately but simultaneously determined. The submarine basalt has 700 ?? 100 ppm total sulfur with ??34S??s of 0.7 ?? 0.1 ???. The sulfate/sulfide molar ratio ranges from 0.15 to 0.56 and the fractionation factor between sulfate and sulfide is +7.5 ?? 1.5???. On the other hand, the concentration and ??34S??s values of the total sulfur in the subaerial basalt are reduced to 150 ?? 50 ppm and -0.8 ?? 0.2???, respectively. The sulfate to sulfide ratio and the fractionation factor between them are also smaller, 0.01 to 0.25 and +3.0???, respectively. Chemical and isotopic evidence strongly suggests that sulfate and sulfide in the submarine basalt are in chemical and isotopic equilibria with each other at magmatic conditions. Their relative abundance and the isotope fractionation factors may be used to estimate the f{hook}o2 and temperature of these basalts at the time of their extrusion onto the sea floor. The observed change in sulfur chemistry and isotopic ratios from the submarine to subaerial basalts can be interpreted as degassing of the SO2 from basalt thereby depleting sulfate and 34S in basalt. The volcanic sulfur gases, predominantly SO2, from the 1971 and 1974 fissures in Kilauea Crater have ??34S values of 0.8 to 0.9%., slightly heavier than the total sulfur in the submarine basalts and definitely heavier than the subaerial basalts, in accord with the above model. However, the ??34S value of sulfur gases (largely SO2) from Sulfur Bank is 8.0%., implying a secondary origin of the sulfur. The ??34S values of native sulfur deposits at various sites of Kilauea and Mauna Loa volcanos, sulfate ions of four deep wells and hydrogen sulfide from a geothermal well along the east rift zone are also reported. The high

  12. Carbonyl sulfide

    Integrated Risk Information System (IRIS)

    Carbonyl sulfide ; CASRN 463 - 58 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  13. Hydrogen sulfide

    Integrated Risk Information System (IRIS)

    Hydrogen sulfide ; 7783 - 06 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  14. Selenium sulfide

    Integrated Risk Information System (IRIS)

    Selenium sulfide ; CASRN 7446 - 34 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  15. Evolution of sulfide mineralization on Mars

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.; Fisher, Duncan S.

    1990-01-01

    It has been previously suggested, on the basis of compositional and petrographic similarities noted between komatites, SNC meteorites, and the silicate portion of the Martian regolith fines, that iron-sulfide ore deposites may exist on Mars. This paper examines the possible locations of Archean-type sulfide and related ore deposits on Mars, their evolution, and the emplacement mechanisms for the ore deposit. The clues to these questions are deduced by applying to Mars the temporal patterns of ore distribution on earth and the experimental observations on sulfur solubility in basaltic melts.

  16. Seawater sulfate reduction and sulfur isotope fractionation in basaltic systems: interaction of seawater with fayalite and magnetite at 200–350°C

    USGS Publications Warehouse

    Shanks, Wayne C.; Bischoff, James L.; Rosenbauer, Robert J.

    1981-01-01

    Systematics of sulfur isotopes in the 250 and 350°C experiments indicate that isotopic equilibrium is reached, and can be modeled as a Rayleigh distillation process. Isotopic composition of hydrothermally produced H2S in natural systems is strongly dependent upon the seawater/basalt ratio in the geothermal system, which controls the relative sulfide contributions from the two important sulfur sources, seawater sulfate and sulfide phases in basalt. Anhydrite precipitation during geothermal heating severely limits sulfate ingress into high temperature interaction zones. Quantitative sulfate reduction can thus be accomplished without producing strongly oxidized rocks and resultant sulfide sulfur isotope values represent a mixture of seawater and basaltic sulfur.

  17. Concentrations and isotope ratios of carbon, nitrogen and sulfur in ocean-floor basalts

    USGS Publications Warehouse

    Sakai, H.; Marais, D.J.D.; Ueda, A.; Moore, J.G.

    1984-01-01

    Fresh submarine basalt glasses from Galapagos Ridge, FAMOUS area, Cayman Trough and Kilauea east rift contain 22 to 160 ppm carbon and 0.3 to 2.8 ppm nitrogen, respectively, as the sums of dissolved species and vesicle-filling gases (CO2 and N2). The large range of variation in carbon content is due to combined effect of depth-dependency of the solubility of carbon in basalt melt and varying extents of vapour loss during magma emplacement as well as in sample crushing. The isotopic ratios of indigenous carbon and nitrogen are in very narrow ranges,-6.2 ?? 0.2% relative to PDB and +0.2 ?? 0.6 %. relative to atmospheric nitrogen, respectively. In basalt samples from Juan de Fuca Ridge, however, isotopically light carbon (??13C = around -24%.) predominates over the indigenous carbon; no indigenous heavy carbon was found. Except for Galapagos Ridge samples, these ocean-floor basalts contain 670 to 1100 ppm sulfur, averaging 810 ppm, in the form of both sulfide and sulfate, whereas basalts from Galapagos Ridge are higher in both sulfur (1490 and 1570 ppm) and iron (11.08% total iron as FeO). The ??34S values average +0.3 ?? 0.5%. with average fractionation factor between sulfate and sulfide of +7.4 ?? 1.6%.. The sulfate/sulfide ratios tend to increase with increasing water content of basalt, probably because the oxygen fugacity increases with increasing water content in basalt melt. ?? 1984.

  18. Origin of the Grande Ronde Basalts, Columbia River Basalt Group

    NASA Astrophysics Data System (ADS)

    Durand, S. R.; Sen, G.; Reidel, S. P.

    2005-12-01

    at 0.2, 1.0 and 1.5 GPa. Because of the pressure limits with the COMAGMAT software, we could not model this composition at higher pressures. Therefore, we searched for pressures at which our calculated mantle-equilibrated melt would be multiply saturated with mantle minerals using the MELTS software. The best fit forward model converges with the best plausible inverse model in that both indicate that most primitive parent melts related to GR could have been multiply saturated at ~1.5-2.0 GPa. We interpret this result to indicate that the parental melts last equilibrated with a peridotitic mantle at 1.5-2.0 GPa and such partial melts rose to 0.2 GPa where they underwent efficient mixing and fractionation before erupting. Our models suggest that the source rock was not eclogitic but a typical upper mantle peridotite, and that the melts had ~0.5% water. We suggest that the plume that generated the GR basalts intruded and displaced much of the lower lithosphere at ~16.5 Ma, perhaps aided by back-arc extension due to subduction of the Farallon plate. Although the plume may have begun melting at a deeper level, the bulk of the melting (which perhaps overwhelmed the earlier melts) did not occur until the plume reached ~60-45 km.

  19. Saturation meter

    DOEpatents

    Gregurech, S.

    1984-08-01

    A saturation meter for use in a pressurized water reactor plant comprising a differential pressure transducer having a first and second pressure sensing means and an alarm. The alarm is connected to the transducer and is preset to activate at a level of saturation prior to the formation of a steam void in the reactor vessel.

  20. Basaltic island sand provenance

    SciTech Connect

    Marsaglia, K.M. . Dept. of Geological Sciences)

    1992-01-01

    The Hawaiian Islands are an ideal location to study basaltic sand provenance in that they are a series of progressively older basaltic shield volcanoes with arid to humid microclimates. Sixty-two sand samples were collected from beaches on the islands of Hawaii, Maui, Oahu and Kauai and petrographically analyzed. The major sand components are calcareous bioclasts, volcanic lithic fragments, and monomineralic grains of dense minerals and plagioclase. Proportions of these components vary from island to island, with bioclastic end members being more prevalent on older islands exhibiting well-developed fringing reef systems and volcanic end members more prevalent on younger, volcanically active islands. Climatic variations across the island of Hawaii are reflected in the percentage of weathered detritus, which is greater on the wetter, northern side of the island. The groundmass of glassy, basaltic lithics is predominantly black tachylite, with lesser brown sideromelane; microlitic and lathwork textures are more common than holohyaline vitric textures. Other common basaltic volcanic lithic fragments are holocrystalline aggregates of silt-sized pyroxene or olivine, opaque minerals and plagioclase. Sands derived from alkalic lavas are texturally and compositionally indistinguishable from sands derived from tholeiitic lavas. Although Hawaiian basaltic sands overlap in composition with magmatic arc-derived sands in terms of their relative QFL, QmPK and LmLvLs percentages, they are dissimilar in that they lack felsic components and are more enriched in lathwork volcanic lithic fragments, holocrystalline volcanic lithic fragments, and dense minerals.

  1. Protection of steel from hydrogen sulfide corrosion by bactericides

    SciTech Connect

    Abbasov, V.M.; Mamedov, I.A.; Abdullaev, E.Sh.

    1995-03-01

    Modern effective inhibitors, Araz-1 and INFKh-4, are recommended for preventing the corrosion of oilfield equipment affected by hydrogen sulfide and sulfate-reducing bacteria. Both inhibitors have undergone full-scale field tests and have shown highly effective inhibition of corrosion in two-phase hydrocarbon-electrolyte media saturated with hydrogen sulfide.

  2. Continental Basaltic Rocks

    NASA Astrophysics Data System (ADS)

    Farmer, G. L.

    2003-12-01

    During the past few decades, geochemical studies of continental basaltic rocks and their petrologic kin have become mainstays of studies of the continental lithosphere. These igneous rocks have taken on such an important role largely because the chemical and isotopic composition of continental basaltic rocks and their mantle (see Chapter 2.05) and crustal xenoliths (see Chapter 3.01) provide the best proxy record available to earth scientists for the chemical and physical evolution of the deep continental lithosphere and underlying mantle, areas that are otherwise resistant to direct study. Keeping this in mind, the primary goal of this chapter is to illustrate how geochemical data can be used both to assess the origin of these rocks and to study the evolution of the continental lithosphere.A complete overview of continental basaltic rocks will not be attempted here, because continental "basalts" come in too wide a range of compositions, and because of the sheer volume of geochemical data available for such rocks worldwide. The scope of the chapter is limited to a discussion of a select group of ultramafic to mafic composition "intraplate" continental igneous rocks consisting primarily of kimberlites, potassic and sodic alkali basalts, and continental flood basalts. Igneous rocks forming at active continental margins, such as convergent or transform plate margins, are important examples of continental magmatism but are not directly discussed here (convergent margin magmas are discussed in Chapters 2.11, 3.11, and 3.18). The geochemistry of intraplate igneous rocks of the ocean basins are covered in Chapters 2.04 and 3.16. Although basaltic magmatism has occurred throughout the Earths history, the majority of the examples presented here are from Mesozoic and Cenozoic volcanic fields due to the more complete preservation of younger continental mafic igneous rocks. While considerable effort has been expended in studying the chemical differentiation of mafic magmas

  3. Potential for Carbon Dioxide Sequestration in Flood Basalts

    SciTech Connect

    McGrail, B. PETER; Schaef, Herbert T.; Ho, Anita M.; Chien, Yi-Ju; Dooley, James J.; Davidson, Casie L.

    2006-12-01

    Flood basalts are a potentially important host medium for geologic sequestration of anthropogenic CO2. Most lava flows have flow tops that are porous, permeable, and have enormous capacity for storage of CO2. Interbedded sediment layers and dense low-permeability basalt rock overlying sequential flows may act as effective seals allowing time for mineralization reactions to occur. Laboratory experiments confirm relatively rapid chemical reaction of CO2-saturated pore water with basalts to form stable carbonate minerals. Calculations suggest a sufficiently short time frame for onset of carbonate precipitation after CO2 injection that verification of in situ mineralization rates appears feasible in field pilot studies. If proven viable, major flood basalts in the U.S. and India would provide significant additional CO2 storage capacity and additional geologic sequestration options in certain regions where more conventional storage options are limited.

  4. Volatiles in Submarine HIMU Basalts from the Austral Islands, South Pacific

    NASA Astrophysics Data System (ADS)

    Nichols, A. R.; Hanyu, T.; Shimizu, K.; Dosso, L.

    2014-12-01

    Submarine basalts have been collected from the slopes of Rurutu and Tubuai in the Austral Islands, South Pacific with the manned submersible Shinkai 6500. Previous work on the bulk radiogenic isotope and trace element chemistry of these samples suggests that the basalts were generated from a HIMU reservoir derived from an ancient subducted slab that was entrained and mixed with the depleted asthenospheric mantle. Olivines and glasses from the submarine basalts show lower 3He/4He than MORB, similar to subaerial basalts from these islands. Sixteen glass chips from the same submarine samples have now undergone in-situ analysis for major elements (including S and Cl) by EPMA, trace elements by LA-ICP-MS, H2O and CO2 by FTIR, and bulk volatile analysis (S, Cl, F) by ion chromatography combined with pyrohydrolysis. H2O ranges from 0.62-2.44 wt%, while CO2 is below detection (<20 ppm). S measured by EPMA ranges from 612-1889 ppm and by bulk analysis from 582-1301 ppm and, with the exception of one sample, concentrations agree well. Cl measured by EPMA ranges from 151-538 ppm, and by bulk analysis from 188-980 ppm. The higher values suggest that the bulk samples may be contaminated by seawater; otherwise Cl correlates strongly with incompatible elements. F measured in the bulk samples ranges from 221-1243 ppm. S correlates positively with FeO and Cu, but not with incompatible elements, suggesting sulfide saturation. While the highest H2O contents may reflect late-stage hydration and are oversaturated at the depth of collection, the low H2O contents (11 samples with 0.62-0.96 wt%) are undersaturated, and there is a positive correlation between the H2O contents of all chips and their incompatible element concentrations. This suggests that H2O/Ce and Cl/Ce filtered for shallow level processes may reflect source compositions, providing constraints on volatiles in the sources of Rurutu and Tubuai, and indications about the efficiency of subduction-related volatile-loss in the

  5. Sulfide chemiluminescence detection

    DOEpatents

    Spurlin, Stanford R.; Yeung, Edward S.

    1985-01-01

    A method of chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction.

  6. Sulfide chemiluminescence detection

    DOEpatents

    Spurlin, S.R.; Yeung, E.S.

    1985-11-26

    A method is described for chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

  7. Massive sulfide deposits and hydrothermal solutions: incremental reaction modeling of mineral precipitation and sulfur isotopic evolution

    SciTech Connect

    Janecky, D.R.

    1986-01-01

    Incremental reaction path modeling of chemical and sulfur isotopic reactions occurring in active hydrothermal vents on the seafloor, in combination with chemical and petrographic data from sulfide samples from the seafloor and massive sulfide ore deposits, allows a detailed examination of the processes involved. This paper presents theoretical models of reactions of two types: (1) adiabatic mixing between hydrothermal solution and seawater, and (2) reaction of hydrothermal solution with sulfide deposit materials. In addition, reaction of hydrothermal solution with sulfide deposit minerals and basalt in feeder zones is discussed.

  8. Sulfide mineralization associated with arc magmatism in the Qilian Block, western China: zircon U-Pb age and Sr-Nd-Os-S isotope constraints from the Yulonggou and Yaqu gabbroic intrusions

    NASA Astrophysics Data System (ADS)

    Zhang, Zhao-Wei; Li, Wen-Yuan; Gao, Yong-Bao; Li, Chusi; Ripley, Edward M.; Kamo, Sandra

    2014-02-01

    The sulfide-bearing Yulonggou and Yaqu mafic intrusions are located in the southern margin of the Qilian Block, Qinghai Province, western China. They are small dike-like bodies mainly composed of gabbros and diorites. Disseminated sulfides (pyrrhotite, pentlandite, and chalcopyrite) are present as concordant lenses within the intrusions. Precise CA-ID-TIMS zircon U-Pb dating yields the crystallization ages of 443.39 ± 0.42 and 440.74 ± 0.33 Ma for the Yulonggou and Yaqu intrusions, respectively. Whole rock samples from both intrusions show light rare earth element (REE) enrichments relative to heavy REE and pronounced negative Nb-Ta anomalies relative to Th and La, which are consistent with the products of arc basaltic magmatism. The Yulonggou intrusion has negative ɛ Nd values from -5.7 to -7.7 and elevated (87Sr/86Sr) i ratios from 0.711 to 0.714. In contrast, the Yaqu intrusion has higher ɛ Nd values from -4.1 to +8.4 and lower (87Sr/86Sr) i ratios from 0.705 to 0.710. The δ34S values of sulfide separates from the Yulonggou and Yaqu deposits vary from 0.8 to 2.4 ‰ and from 2 to 4.3 ‰, respectively. The γ Os values of sulfide separates from the Yulonggou and Yaqu deposits vary between 80 and 123 and between 963 and 1,191, respectively. Higher γ Os values coupled with higher δ34S values for the Yaqu deposit relative to the Yulonggou deposit indicate that external sulfur played a bigger role in sulfide mineralization in the Yaqu intrusion than in the Yulonggou intrusion. Mixing calculations using Sr-Nd isotope data show that contamination with siliceous crustal materials is more pronounced in the Yulonggou intrusion (up to 20 wt%) than in the Yaqu intrusion (<15 wt%). The distribution of sulfides in both intrusions is consistent with multiple emplacements of sulfide-saturated magmas from depth. The Yulonggou and Yaqu sulfide deposits are not economically valuable under current market condition due to small sizes and low Ni grades, which can be explained

  9. Evidence for thermal erosion of basalt and hybridization of komatiite at Kambalda, Western Australia

    SciTech Connect

    Lesher, C.M.

    1985-01-01

    Archean komatiite-associated Ni-sulfide ores in Western Australia are hosted by cumulate metakomatiites and are localized in footwall embayments. Structural, stratigraphical, and volcanological studies of the type-examples of these deposits at Kambalda, Western Australia suggest i) that the host units represent linear lava conduits and ii) that the embayments are volcanic features, modified by deformation. The sulfide ore are interpreted to have formed by assimilation of sulfidic, cherty sediments beneath the thermally-active lava conduits. Transgressive magmatic contacts between massive sulfide and pillowed metabasalt provide unequivocal evidence for erosion of basalt by highly thermally conductive massive sulfides. Evidence for thermal erosion of basalt by komatiite is more equivocal as contacts between the two lithologies are normally recrystallized and marked by chloritic metasomatic reaction zones. Thermal erosion channels produced experimentally by Huppert et al. (1984) are morphologically similar to the embayments at Kambalda, but it is unlikely that the embayments in these deposits have been generated by thermal erosion, for several reason: 1) Some embayments contain uneroded metasediments and predate emplacement of the ores and host units. 2) Some embayments appear to be broadly stratigraphically conformable within the footwall metabasalt sequence. 3) Some embayments are elliptical in outline and could not have formed by thermal erosion beneath a lava conduit. The embayments probably represent volcanic-topographic irregularities in the surface of the footwall basalt that have been variably modified by thermal erosion.

  10. Negligible sulfur isotope fractionation during partial melting: Evidence from Garrett transform fault basalts, implications for the late-veneer and the hadean matte

    NASA Astrophysics Data System (ADS)

    Labidi, J.; Cartigny, P.

    2016-10-01

    We report the quadruple sulfur isotope compositions, sulfur contents and speciation major and trace elements (including copper and chlorine abundances) of eleven basalts collected in the Garrett transform fault. We combine these data to discuss the absence of S isotopic fractionation along both partial melting and low-pressure fractional crystallization. The variations of K2O/TiO2 and La/SmN-ratios (respectively between 0.017 and 0.067, and between 0.31 and 0.59) suggest a range of depletion in Garrett lavas that includes ultra depleted samples (K2O/TiO2 < 0.03). The remarkable level of incompatible element depletion is consistent with re-melting of a depleted source. Contrasting with incompatible element depletion, all samples display similar S and Cu abundance (at a given major-element composition) to mid-ocean ridge basalts (MORB). This indicates that Garrett Intra Transform Lavas (ITL) are sulfide saturated as MORB are. Copper content for Garrett parental melts (MgO >8%) are ∼80 ppm, indistinguishable from MORBs. This requires their mantle sources, variably depleted in incompatible element, to host residual sulfide buffering the Cu content of all erupted melts. We calculate a minimum S content for the source of ultra-depleted Garrett lavas of 100 ± 40ppmS, i.e. roughly a factor of 2 below the MORB mantle source. After exclusion of a single sample with Cl/K ratio >0.1 that likely experienced hydrothermal sulfide assimilation, Garrett ITLs display homogeneous δ34 S, Δ33 S and Δ36 S values with averages of - 0.68 ± 0.08 ‰, + 0.010 ± 0.005 ‰ and - 0.04 ± 0.04 ‰, respectively (all 1σ, n = 10). The δ34 S values display no relationship with either K2O/TiO2 variations or extent sulfide fractionation. From these observations, we derive a 34S/32S fractionation factor between exsolved sulfides and sulfide dissolved in silicate melts of 1.0000 ± 0.0003. The S isotopic fractionation during partial melting can thus be considered as negligible, and both

  11. Origin of Magnetic High at Basalt-Ultramafic Hosted Hydrothermal Vent Field in the Central Indian Ridge

    NASA Astrophysics Data System (ADS)

    Fujii, M.; Okino, K.; Sato, T.; Sato, H.; Nakamura, K.

    2014-12-01

    Hydrothermal alteration processes can change crustal magnetization by destruction and creation of magnetic minerals. In the Yokoniwa hydrothermal vent field (YHVF), located at the NTO-massif in the Central Indian Ridge, a high magnetization zone (with ~12 A/m in ~200 m-scale) was discovered by previous deepsea AUV survey. Basalts and ultramafic rocks were found around the YHVF, however the origin of magnetic high and its relationship with hydrothermal activity are remains to be investigated. Therefore, we conducted additional magnetic field measurement, rock sampling, and geological observation using submersible Shinkai 6500 during the YK09-13 and YK13-03 cruises. Vector geomagnetic field were obtained along the dive tracks at an altitude of ~ 10 m. The crustal absolute magnetization is estimated using the 2D and 3D forward modeling technique. The values of magnetization show ~10 A/m just around the YHVF. This value is consistent with that of equivalent magnetization deduced from AUV data. Rock magnetic characters were measured for 8 basalts, 4 dolerites, 5 sulfides, and 30 serpentinized peridotites (SPs). The measurements of NRM, magnetic susceptibility, magnetic hysteresis, low (6-300K) and high (50-700°C) temperature magnetization curves were performed. The estimated magnetization values are 0.1-6 A/m in basalts, 0.2-0.6 A/m in dolerites, and <0.1 A/m in sulfides. The SPs show strong magnetization of 0.4-11 A/m. The magnetic grain sizes ranges over single domain to pseudo-single domain. The temperature-magnetization curves clearly show the Verway transition and Currie temperature of 580 °C, therefore magnetic carrier of SPs is supposed as pure magnetite, which is created during serpentinization process. Serpentinization degree (Sd) was also estimated by grain density measurement based on empirical formula from Oufi et al., 2002. Amount of magnetite was also estimated from saturation magnetization. The results show that the values of Sd vary in a range from 17

  12. Cadmium sulfide membranes

    DOEpatents

    Spanhel, Lubomir; Anderson, Marc A.

    1992-07-07

    A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

  13. Cadmium sulfide membranes

    DOEpatents

    Spanhel, Lubomir; Anderson, Marc A.

    1991-10-22

    A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

  14. SULFIDE MINERALS IN SEDIMENTS

    EPA Science Inventory

    The formation processes of metal sulfides in sediments, especially iron sulfides, have been the subjects of intense scientific research because of linkages to the global biogeochemical cycles of iron, sulfur, carbon, and oxygen. Transition metal sulfides (e.g., NiS, CuS, ZnS, Cd...

  15. Distributed Saturation

    NASA Technical Reports Server (NTRS)

    Chung, Ming-Ying; Ciardo, Gianfranco; Siminiceanu, Radu I.

    2007-01-01

    The Saturation algorithm for symbolic state-space generation, has been a recent break-through in the exhaustive veri cation of complex systems, in particular globally-asyn- chronous/locally-synchronous systems. The algorithm uses a very compact Multiway Decision Diagram (MDD) encoding for states and the fastest symbolic exploration algo- rithm to date. The distributed version of Saturation uses the overall memory available on a network of workstations (NOW) to efficiently spread the memory load during the highly irregular exploration. A crucial factor in limiting the memory consumption during the symbolic state-space generation is the ability to perform garbage collection to free up the memory occupied by dead nodes. However, garbage collection over a NOW requires a nontrivial communication overhead. In addition, operation cache policies become critical while analyzing large-scale systems using the symbolic approach. In this technical report, we develop a garbage collection scheme and several operation cache policies to help on solving extremely complex systems. Experiments show that our schemes improve the performance of the original distributed implementation, SmArTNow, in terms of time and memory efficiency.

  16. Very high potassium (VHK) basalt - Complications in mare basalt petrogenesis

    NASA Technical Reports Server (NTRS)

    Shervais, J. W.; Taylor, L. A.; Laul, J. C.; Shih, C.-Y.; Nyquist, L. E.

    1985-01-01

    The first comprehensive report on the petrology and geochemistry of Apollo 14 VHK (Very High Potassium) basalts and their implications for lunar evolution is presented. The reported data are most consistent with the hypothesis that VHK basalts formed through the partial assimilation of granite by a normal low-Ti, high-Al mare basalt magma. Assimilation was preceded by the diffusion-controlled exchange of alkalis and Ba between basalt magma and the low-temperature melt fraction of the granite. Hypotheses involving volatile/nonvolatile fractionations or long-term enrichment of the source regions in K are inconsistent with the suprachondritic Ba/La ratios and low initial Sr-87/Sr-86 ratios of VHK basalt. An important implication of this conclusion is that granite should be a significant component of the lunar crust at the Apollo 14 site.

  17. Basalt-CO2-H2O Interactions and Variability in Carbonate Mineralization Rates

    SciTech Connect

    Schaef, Herbert T.; McGrail, B. Peter; Owen, Antionette T.

    2009-02-01

    Flood basalts are receiving increasing attention as possible host formations for geologic sequestration of anthropogenic CO2, with studies underway in the U.S., India, Iceland, and Canada. Our previous laboratory studies with Columbia River basalts showed relative quick precipitation of carbonate minerals compared to other siliclastic rocks when batch reacted with water and supercritical CO2. In this study, our prior work with Columbia River basalt was extended to tests with basalts from the eastern U.S., India, and Africa. The basalts are all similar in bulk chemistry and share common minerals such as plagioclase, augite, and a glassy mesostasis. Single pass flow through dissolution experiments under dilute solution and mildly acidic conditions indicate similar cation release behavior among the basalt samples tested. Despite similar bulk chemistry and apparent dissolution kinetics, long-term static experiments with CO2 saturated water show significant differences in rates of mineralization as well as precipitate chemistry and morphology. For example, basalt from the Newark Basin in the U.S. is by far the most reactive of any basalt tested to date. Carbonate reaction products for the Newark Basin basalt were globular in form and contained significantly more Fe than the secondary carbonates that precipitated on the other basalt samples. Calcite grains with classic “dogtooth spar” morphology and trace cation substitution (Mg and Mn) were observed in post-reacted samples associated with the Columbia River basalts. Other basalts produced solid precipitates with compositions that varied chemically throughout the entire testing period. Polished cross sections of the reacted grains show precipitate overgrowths with irregular regions outlined by dark and bright layers indicative of zonations of different compositions. For example, SEM-EDX analysis across carbonate precipitates, which resulted from 854 days of reaction of the Central Atlantic Mafic Province (CAMP

  18. Why Hexagonal Basalt Columns?

    PubMed

    Hofmann, Martin; Anderssohn, Robert; Bahr, Hans-Achim; Weiß, Hans-Jürgen; Nellesen, Jens

    2015-10-01

    Basalt columns with their preferably hexagonal cross sections are a fascinating example of pattern formation by crack propagation. Junctions of three propagating crack faces rearrange such that the initial right angles between them tend to approach 120°, which enables the cracks to form a pattern of regular hexagons. To promote understanding of the path on which the ideal configuration can be reached, two periodically repeatable models are presented here involving linear elastic fracture mechanics and applying the principle of maximum energy release rate. They describe the evolution of the crack pattern as a transition from rectangular start configuration to the hexagonal pattern. This is done analytically and by means of three-dimensional finite element simulation. The latter technique reproduces the curved crack path involved in this transition.

  19. Why Hexagonal Basalt Columns?

    PubMed

    Hofmann, Martin; Anderssohn, Robert; Bahr, Hans-Achim; Weiß, Hans-Jürgen; Nellesen, Jens

    2015-10-01

    Basalt columns with their preferably hexagonal cross sections are a fascinating example of pattern formation by crack propagation. Junctions of three propagating crack faces rearrange such that the initial right angles between them tend to approach 120°, which enables the cracks to form a pattern of regular hexagons. To promote understanding of the path on which the ideal configuration can be reached, two periodically repeatable models are presented here involving linear elastic fracture mechanics and applying the principle of maximum energy release rate. They describe the evolution of the crack pattern as a transition from rectangular start configuration to the hexagonal pattern. This is done analytically and by means of three-dimensional finite element simulation. The latter technique reproduces the curved crack path involved in this transition. PMID:26550724

  20. Mineralization, alteration, and hydrothermal metamorphism of the ophiolite-hosted Turner-Albright sulfide deposit, southwestern Oregon

    USGS Publications Warehouse

    Zierenberg, R.A.; Shanks, Wayne C.; Seyfried, W.E.; Koski, R.A.; Strickler, M.D.

    1988-01-01

    The Turner-Albright sulfide deposit, part of the Josephine ophiolite, formed on and below the seafloor during Late Jurassic volcanism at a back arc spreading center. Ore fluids were probably localized by faults which were active on the seafloor at the time of sulfide deposition. The uppermost massive sulfide formed on the seafloor at hydrothermal vents. The bulk of the sulfide mineralization formed below the seafloor within olivine basalt hyaloclastite erupted near the time of mineralization. Infiltration of hydrothermal fluid into the hyaloclastite altered the rock. The fluid responsible for the hydrothermal alteration was evolved seawater with low pH and Mg and high Fe. The average value of sulfide and the difference between sulfide and contemporaneous seawater sulfate values are similar to ophiolite-hosted sulfide deposits in Cyprus. Mudstone and clinopyroxene basalt above the sulfide horizons were not altered by the ore-transporting hydrothermal fluid, but these rocks were hydrothermally metamorphosed by altered seawater heated by deep circulation into hot oceanic crust. This subseafloor metamorphism produced a mineral assemblage typical of prehnite-pumpellyite facies metamorphism. Exchange with altered seawater increased the whole-rock ??18O of the basalts to values of 9.4-11.2%. -from Authors

  1. Contrasting behavior of noble-metal elements during magmatic differentiation in basalts from the Cook Islands, Polynesia

    NASA Astrophysics Data System (ADS)

    Tatsumi, Yoshiyuki; Oguri, Kiwamu; Shimoda, Gen; Kogiso, Tetsu; Barsczus, Hans G.

    2000-02-01

    Concentrations of noble metals (Ir, Ru, Rh, Pt, Pd, and Au) in ocean-island basalts from the Cook Islands, Polynesia, were determined by improved fire-assay and tellurium coprecipitation techniques with an inductively-coupled-plasma mass spectrometer. Isotope, major element, and trace element compositions of these basalts indicate that the present samples include distinctive HIMU (high μ = high 238U/204Pb) and normal non-HIMU basalts. Examination based on Ni-Mg-Fe partitioning between olivine and liquid suggests an only minor effect of accumulation of phenocrysts in governing the compositional variations of the present samples. The fractionation trends obtained show monotonic decrease and increase in noble-metal elements with decreasing MgO content in HIMU and non-HIMU basalts, respectively. These characteristic trends indicate that HIMU magmas are differentiated by fractional crystallization and have higher sulfide/silicate ratios than non-HIMU basalts.

  2. H2S Injection and Sequestration into Basalt - The SulFix Project

    NASA Astrophysics Data System (ADS)

    Gudbrandsson, S.; Moola, P.; Stefansson, A.

    2014-12-01

    Atmospheric H2S emissions are among major environmental concern associated with geothermal energy utilization. It is therefore of great importance for the geothermal power sector to reduce H2S emissions. Known solutions for H2S neutralization are both expensive and include production of elemental sulfur and sulfuric acid that needs to be disposed of. Icelandic energy companies that utilize geothermal power for electricity production have decided to try to find an environmentally friendly and economically feasible solution to reduce the H2S emission, in a joint venture called SulFix. The aim of SulFix project is to explore the possibilities of injecting H2S dissolved in water into basaltic formations in close proximity to the power plants for permanent fixation as sulfides. The formation of sulfides is a natural process in geothermal systems. Due to basalt being rich in iron and dissolving readily at acidic conditions, it is feasible to re-inject the H2S dissolved in water, into basaltic formations to form pyrite. To estimate the mineralization rates of H2S, in the basaltic formation, flow through experiments in columns were conducted at various H2S concentrations, temperatures (100 - 240°C) and both fresh and altered basaltic glass. The results indicate that pyrite rapidly forms during injection into fresh basalt but the precipiation in altered basalt is slower. Three different alteration stages, as a function of distance from inlet, can be observed in the column with fresh basaltic glass; (1) dissolution features along with precipitation, (2) precipitation increases, both sulfides and other secondary minerals and (3) the basalt looks to be unaltered and little if any precipitation is observed. The sulfur has precipitated in the first half of the column and thereafter the solution is possibly close to be supersaturated with respect to the rock. These results indicate that the H2S sequestration into basalt is possible under geothermal conditions. The rate limiting

  3. Saturated fat (image)

    MedlinePlus

    ... saturated fats. Vegetable sources of saturated fat include coconut and palm oils. When looking at a food label, pay close ... saturated fats. Vegetable sources of saturated fat include coconut and palm oils. When looking at a food label, pay close ...

  4. Limitations in determining redox chemistry in basalt groundwaters at the Hanford site

    SciTech Connect

    Dill, J.A.; Jones, T.E.; Marcy, A.D.; West, M.H.

    1986-03-01

    The oxidation-reduction (redox) chemistry of the basalt groundwater system will be an important factor governing both the design and performance of a high-level nuclear waste repository in basalt. Although the redox state of the basalt groundwater system is inherently difficult to measure, there are a number of types of measurements that provide valuable information on this subject. These measurements include concentrations of dissolved sulfide, ferrous iron, electrode redox potential, and groundwater reducing capacity. These measurements have been made on a limited basis in a number of different repository test horizons. Taken collectively, the results of these measurements suggest that both sulfide and ferrous iron play an important role in the establishment of the basalt groundwater redox condition. Thermodynamic calculations of redox potential (E/sub h/) based on these measurements are indicative of an E/sub h/ of -0.4 V. Additional measurements are proposed that will provide a more complete understanding of basalt groundwater redox conditions. The proposed measurements include a more in-depth analysis of redox active species as well as quantification of dissolved gas species such as oxygen and methane.

  5. Sulfide capacities of fayalite-base slags

    NASA Astrophysics Data System (ADS)

    Simeonov, S. R.; Sridhar, R.; Toguri, J. M.

    1995-04-01

    The sulfide capacities of fayalite-base slags were measured by a gas-slag equilibration technique under controlled oxygen and sulfur potentials similar to those encountered in the pyrometallurgical processing of nonferrous metals. The oxygen pressure range was from 10-9.5 to 10-11 MPa and the sulfur pressure range from 10-3 to 10-4.5 MPa, over a temperature range of 1473 to 1623 K. The slags studied were FeO-SiO2 at silica saturation and those with addition of CaO, MgO, and Al2O3 to determine their effect on sulfide capacities. For these slags, the sulfide capacities were found to vary from 10-3.3 to 10-5. The sulfide capacities increased with increasing temperature from 1473 to 1623 K. A comparison of the reported plant data on sulfur content of industrial slags shows good agreement with the present experimental results. The present data will be useful in estimating metal losses in slag due to metal sulfide entrainment in nonferrous smelters.

  6. Hanford basalt flow mineralogy

    SciTech Connect

    Ames, L.L.

    1980-09-01

    Mineralogy of the core samples from five core wells was examined in some detail. The primary mineralogy study included an optical examination of polished mounts, photomicrographs, chemical analyses of feldspars, pyroxenes, metallic oxides and microcrystalline groundmasses and determination from the chemical analyses of the varieties of feldspars, pyroxenes and metallic oxides. From the primary mineralogy data, a firm understanding of the average Hanford basalt flow primary mineralogy emerged. The average primary feldspar was a laboradorite, the average pyroxene was an augite and the average metallic oxide was a solid solution of ilmenite and magnetite. Secondary mineralization consisted of vug filling and joint coating, chiefly with a nontronite-beidellite clay, several zeolites, quartz, calcite, and opal. Specific flow units also were examined to determine the possibility of using the mineralogy to trace flows between core wells. These included units of the Pomona, the Umatilla and a high chromium flow just below the Huntzinger. In the Umatilla, or high barium flow, the compositional variation of the feldspars was unique in range. The pyroxenes in the Pomona were relatively highly zoned and accumulated chromium. The high chromium flow contained chromium spinels that graded in chromium content into simple magnetites very low in chromium content. A study of the statistical relationships of flow unit chemical constituents showed that flow unit constituents could be roughly correlated between wells. The probable cause of the correlation was on-going physical-chemical changes in the source magma.

  7. Flood basalts and mass extinctions

    NASA Technical Reports Server (NTRS)

    Morgan, W. Jason

    1988-01-01

    There appears to be a correlation between the times of flood basalts and mass-extinction events. There is a correlation of flood basalts and hotspot tracks--flood basalts appear to mark the beginning of a new hotspot. Perhaps there is an initial instability in the mantle that bursts forth as a flood basalt but then becomes a steady trickle that persists for many tens of millions of years. Suppose that flood basalts and not impacts cause the environmental changes that lead to mass-extinctions. This is a very testable hypothesis: it predicts that the ages of the flows should agree exactly with the times of extinctions. The Deccan and K-T ages agree with this hypothesis; An iridium anomaly at extinction boundaries apparently can be explained by a scaled-up eruption of the Hawaiian type; the occurrence of shocked-quartz is more of a problem. However if the flood basalts are all well dated and their ages indeed agree with extinction times, then surely some mechanism to appropriately produce shocked-quartz will be found.

  8. Nickel in high-alumina basalts

    USGS Publications Warehouse

    Hedge, C.E.

    1971-01-01

    New analyses of high-alumina basalts reveal an average nickel content higher than previously indicated. Ni in high-alumina basalts correlates with magnesium in the same way as it does in other basalt types. There is therefore no reason, based on Ni contents, to hypothesize a special origin for high-alumina basalts and it is permissible (based on Ni contents) to form andesites by fractional crystallization from high-alumina basalts. ?? 1971.

  9. Decompression-Induced Crystallization of Hydrous Basalt

    NASA Astrophysics Data System (ADS)

    Teasdale, R.; Brooker, R. A.

    2014-12-01

    Decompression-induced crystallization of hydrous basalt during magma ascent from 1.5 kb (150 MPa) is quantified using isothermal decompression TZM experiments. The starting composition is a synthetic glass based on the 1921 Kilauea basalt, with 1% H2O added. In all cases, the liquidus phase is aluminous spinel, followed by clinopyroxene, then plagioclase. The plagioclase liquidus temperatures for isobaric (equilibrium) experiments range from 1175°C (at 1.5 kb) to 1217°C (at 200b), which are 35-75°C hotter than predicted by MELTS (Ghiorso & Sack 1995). Experiments were decompressed at 1kb/hr and quenched at 800, 400, 200, or 100b for three temperatures (1160°, 1150°, and 1140°C). Plagioclase crystals formed during decompression have long axes that range from less than 1 micron to 20 microns. Increasing decompression yields larger plagioclase crystal sizes and aspect ratios for experiments at equal temperatures. However, the number of crystals does not vary systematically, indicating that crystallization is dominated by growth rather than nucleation during decompression. Plagioclase compositions for experiments were measured with University of Bristol's Electron Microprobe and the Hyperprobe with Field Emission Gun. Plagioclase compositions from equilibrium experiments (An60-An80) span the range of those from decompression experiments (An60-An73). Equilibrium experiments generated higher An compositions at lower pressures (500b) than at higher pressure (1.5kb) but do not systematically vary with temperature. Variations in plagioclase compositions are minimal above H2O saturation (100-200°C, based on Papale et al., 2006). Below H2O saturation, An content decreases slightly, by approximately 4% An. One application of this work is better characterization of groundmass crystallization in hydrous basalt as it traverses the conduit during eruption. This work also provides a means of distinguishing groundmass plagioclase related to decompression from crystals

  10. Basaltic Lava Channels

    NASA Astrophysics Data System (ADS)

    Cashman, K. V.; Griffiths, R. W.; Kerr, R. C.

    2004-12-01

    or channel bends that exposes more core lava to cooling than simply that of the shear zones. Thus the channel geometry plays a major role in the thermal history of a flow. As lava flows rarely flow through pre-existing channels of prescribed geometry, we have performed an additional set of analog laboratory experiments to determine the relationship between flow rate, slope, and channel formation in solidifying flows. All flows develop stable uniform channels within solidified levees except when the flow rate is sufficiently low to permit flow front solidification, inflation, and tube formation. On constant slopes, increasing flow rates result in increases in both the rate of flow advance rate and the channel width, and a decrease in levee width. At constant flow rates, both channel width and levee width decrease with increasing slope while flow advance rate increases. Limited data on the geometry of basaltic lava channels indicate that experimental data are consistent with field observations, however, both additional field data and scaling relationships are required to fully utilize the laboratory experiments to predict channel development in basaltic lava flows.

  11. Pb isotopes in sulfides from mid-ocean ridge hydrothermal sites

    SciTech Connect

    LeHuray, A.P.; Church, S.E.; Koski, R.A.; Bouse, R.M.

    1988-04-01

    The authors report Pb isotope ratios of sulfides deposited at seven recently active mid-ocean ridge (MOR) hydrothermal vents. Sulfides from three sediment-starved sites on the Juan de Fuca Ridge contain Pb with isotope ratios identical to their local basaltic sources. Lead in two deposits from the sediment-covered Escanaba Trough, Gorda Ridge, is derived from the sediments and does not appear to contain any basaltic component. There is a range of isotope ratios in a Guaymas Basin deposit, consistent with a mixture of sediment and MOR basalt Pb. Lead in a Galapagos deposit differs slightly from known Galapagos basalt Pb isotope values. The faithful record of Pb isotope signatures of local sources in MOR sulfides indicates that isotope ratios from ancient analogues ca be used as accurate reflections of ancient oceanic crustal values in ophiolite-hosted deposits and continental crustal averages in sediment-hosted deposits. The preservation of primary ophiolitic or continental crustal Pb isotope signatures in ancient MOR sulfides provides a powerful tool for investigation of crustal evolution and for fingerprinting ancient terranes.

  12. Sulfide Mineralogy and Geochemistry

    NASA Astrophysics Data System (ADS)

    Dilles, John

    2007-02-01

    Reviews in Mineralogy and Geochemistry Series, Volume 61 David J. Vaughan, Editor Geochemical Society and Mineralogical Society of America; ISBN 0-939950-73-1 xiii + 714 pp.; 2006; $40. Sulfide minerals as a class represent important minor rock-forming minerals, but they are generally known as the chief sources of many economic metallic ores. In the past two decades, sulfide research has been extended to include important roles in environmental geology of sulfide weathering and resultant acid mine drainage, as well as in geomicrobiology in which bacteria make use of sulfides for metabolic energy sources. In the latter respect, sulfides played an important role in early evolution of life on Earth and in geochemical cycling of elements in the Earth's crust and hydrosphere.

  13. Geology, mineralogy, and chemistry of sediment-hosted clastic massive sulfides in shallow cores, Middle Valley, northern Juan de Fuca Ridge

    SciTech Connect

    Goodfellow, W.D.; Franklin, J.M. )

    1993-12-01

    Middle Valley is a sediment-covered rift near the northern end of Juan de Fuca Ridge. Hydrothermal fluids are presently being discharged at two vent fields about 3 km apart, Bent Hill and the area of active venting. The hydrothermally active chimneys at both Bent Hill and the area of active venting consist of anhydrite and Mg-rich silicates with minor pyrite, Cu-Fe sulfide, sphalerite, and galena. Hydrothermal discharge in these areas appears to be focused along extensional faults. At the Bent Hill massive sulfide deposit, clastic sulfide layers are interbedded with hydrothermally altered and unaltered hemipelagic and turbiditic sediment along the flanks of the sulfide mound. Sulfide textures and mineralogy suggest that the Bent Hill sulfide mound formed by the build-up and collapse of sulfide chimneys, the resedimentation of sulfide debris and the formation of clastic sulfide layers, and the infilling and replacement of clastic sulfides by hydrothermal fluids near vents. Sulfur isotope values that are consistently more positive than basaltic sulfur support the addition of seawater sulfur. Pb isotope values for the Bent Hill deposit that are transitional between midocean ridge basalt (MORB) and Middle Valley sediments indicate that the sulfides probably formed from fluids which originated in the oceanic crust but which have been modified by reaction with lower temperature (<274 C) fluids generated in the sedimentary pile, similar to those now venting in Middle Valley.

  14. Energy and Carbon Flow: Comparing ultramafic- and basalt-hosted vents

    NASA Astrophysics Data System (ADS)

    Perner, M.; Bach, W.; Seifert, R.; Strauss, H.; Laroche, J.

    2010-12-01

    In deep-sea vent habitats hydrothermal fluids provide the grounds for life by supplying reduced inorganic compounds (e.g. H2, sulfide). Chemolithoautotrophs can oxidize these substrates hereby yielding energy, which can then be used to fuel autotrophic CO2 fixation. Depending on the type of host rocks (and the degree of admixed ambient seawater) the availability of inorganic electron donors can vary considerably. While in ultramafic-hosted vents H2 levels are high and H2-oxidizing metabolisms are thought to dominate, in basalt-hosted vents, H2 is much lower and microbial sulfide oxidation is considered to prevail [1, 2]. We have investigated the effect of H2 and sulfide availability on the microbial community of distinct H2-rich and H2-poor vent sites along the Mid-Atlantic Ridge. Hydrothermally influenced samples were collected from the H2-rich ultramafic-hosted Logatchev field (15°N) and the comparatively H2-poor basalt-hosted vents from 5°S and 9°S. We conducted catabolic energy calculations to estimate the potential of various electron donors to function as microbial energy sources. We performed incubation experiments with hydrothermal fluids amended with H2 or sulfide and radioactively labelled bicarbonate and determined H2 and sulfide consumption and carbon incorporation rates. We constructed metagenomic libraries for sequence-based screening of genes encoding key enzymes for H2 uptake (NiFe uptake hydrogenases, group 1), sulfide oxidation (sulfide quinone oxidoreductase, sqr) and CO2 fixation pathways (RubisCOs of the Calvin cycle [CBB] and beta-subunit of the ATP citrate lyase of the reductive tricarboxylic acid cycle [rTCA]). We evaluated parts of the metagenomes from basalt-hosted sites by pyrosequencing. Based on our incubation experiments - under the conditions applied - we could not confirm that generally H2 consumption rates and biomass syntheses in fluids derived from ultramafic-hosted locations are significantly enhanced over those from basalt

  15. Injection and Monitoring at the Wallula Basalt Pilot Project

    SciTech Connect

    McGrail, B. Peter; Spane, Frank A.; Amonette, James E.; Thompson, Christopher J.; Brown, Christopher F.

    2014-01-01

    Continental flood basalts represent one of the largest geologic structures on earth but have received comparatively little attention for geologic storage of CO2. Flood basalt lava flows have flow tops that are porous, permeable, and have large potential capacity for storage of CO2. In appropriate geologic settings, interbedded sediment layers and dense low-permeability basalt rock flow interior sections may act as effective seals allowing time for mineralization reactions to occur. Previous laboratory experiments showed the relatively rapid chemical reaction of CO2-saturated pore water with basalts to form stable carbonate minerals. However, recent laboratory tests with water-saturated supercritical CO2 show that mineralization reactions occur in this phase as well, providing a second and potentially more important mineralization pathway than was previously understood. Field testing of these concepts is proceeding with drilling of the world’s first supercritical CO2 injection well in flood basalt being completed in May 2009 near the township of Wallula in Washington State and corresponding CO2 injection permit granted by the State of Washington in March 2011. Injection of a nominal 1000 MT of CO2 was completed in August 2013 and site monitoring is in progress. Well logging conducted immediately after injection termination confirmed the presence of CO2 predominantly within the upper flow top region, and showed no evidence of vertical CO2 migration outside the well casing. Shallow soil gas samples collected around the injection well show no evidence of leakage and fluid and gas samples collected from the injection zone show strongly elevated concentrations of Ca, Mg, Mn, and Fe and 13C/18O isotopic shifts that are consistent with basalt-water chemical reactions. If proven viable by this field test and others that are in progress or being planned, major flood basalts in the U.S., India, and perhaps Australia would provide significant additional CO2 storage capacity

  16. Injection and Monitoring at the Wallula Basalt Pilot Project

    DOE PAGES

    McGrail, B. Peter; Spane, Frank A.; Amonette, James E.; Thompson, Christopher J.; Brown, Christopher F.

    2014-01-01

    Continental flood basalts represent one of the largest geologic structures on earth but have received comparatively little attention for geologic storage of CO2. Flood basalt lava flows have flow tops that are porous, permeable, and have large potential capacity for storage of CO2. In appropriate geologic settings, interbedded sediment layers and dense low-permeability basalt rock flow interior sections may act as effective seals allowing time for mineralization reactions to occur. Previous laboratory experiments showed the relatively rapid chemical reaction of CO2-saturated pore water with basalts to form stable carbonate minerals. However, recent laboratory tests with water-saturated supercritical CO2 show thatmore » mineralization reactions occur in this phase as well, providing a second and potentially more important mineralization pathway than was previously understood. Field testing of these concepts is proceeding with drilling of the world’s first supercritical CO2 injection well in flood basalt being completed in May 2009 near the township of Wallula in Washington State and corresponding CO2 injection permit granted by the State of Washington in March 2011. Injection of a nominal 1000 MT of CO2 was completed in August 2013 and site monitoring is in progress. Well logging conducted immediately after injection termination confirmed the presence of CO2 predominantly within the upper flow top region, and showed no evidence of vertical CO2 migration outside the well casing. Shallow soil gas samples collected around the injection well show no evidence of leakage and fluid and gas samples collected from the injection zone show strongly elevated concentrations of Ca, Mg, Mn, and Fe and 13C/18O isotopic shifts that are consistent with basalt-water chemical reactions. If proven viable by this field test and others that are in progress or being planned, major flood basalts in the U.S., India, and perhaps Australia would provide significant additional CO2 storage

  17. Enriched Pt-Re-Os isotope systematics in plume lavas explained by metasomatic sulfides.

    PubMed

    Luguet, Ambre; Graham Pearson, D; Nowell, Geoff M; Dreher, Scott T; Coggon, Judith A; Spetsius, Zdislav V; Parman, Stephen W

    2008-01-25

    To explain the elevated osmium isotope (186Os-187Os) signatures in oceanic basalts, the possibility of material flux from the metallic core into the crust has been invoked. This hypothesis conflicts with theoretical constraints on Earth's thermal and dynamic history. To test the veracity and uniqueness of elevated 186Os-187Os in tracing core-mantle exchange, we present highly siderophile element analyses of pyroxenites, eclogites plus their sulfides, and new 186Os/188Os measurements on pyroxenites and platinum-rich alloys. Modeling shows that involvement in the mantle source of either bulk pyroxenite or, more likely, metasomatic sulfides derived from either pyroxenite or peridotite melts can explain the 186Os-187Os signatures of oceanic basalts. This removes the requirement for core-mantle exchange and provides an effective mechanism for generating Os isotope diversity in basalt source regions. PMID:18218894

  18. Enriched Pt-Re-Os isotope systematics in plume lavas explained by metasomatic sulfides.

    PubMed

    Luguet, Ambre; Graham Pearson, D; Nowell, Geoff M; Dreher, Scott T; Coggon, Judith A; Spetsius, Zdislav V; Parman, Stephen W

    2008-01-25

    To explain the elevated osmium isotope (186Os-187Os) signatures in oceanic basalts, the possibility of material flux from the metallic core into the crust has been invoked. This hypothesis conflicts with theoretical constraints on Earth's thermal and dynamic history. To test the veracity and uniqueness of elevated 186Os-187Os in tracing core-mantle exchange, we present highly siderophile element analyses of pyroxenites, eclogites plus their sulfides, and new 186Os/188Os measurements on pyroxenites and platinum-rich alloys. Modeling shows that involvement in the mantle source of either bulk pyroxenite or, more likely, metasomatic sulfides derived from either pyroxenite or peridotite melts can explain the 186Os-187Os signatures of oceanic basalts. This removes the requirement for core-mantle exchange and provides an effective mechanism for generating Os isotope diversity in basalt source regions.

  19. Electric potential changes prior to shear fracture in dry and saturated rocks

    NASA Astrophysics Data System (ADS)

    Yoshida, Shingo; Clint, Oswald C.; Sammonds, Peter R.

    Electric potential changes before shear rupture were measured using Darley Dale sandstone (quartz-rich) and Icelandic basalt (quartz-free) on both dry specimens and in the presence of pore fluid. We find that electric potential changed markedly just prior to dynamic rupture in dry and saturated sandstones and saturated basalt but we did not detect precursory signals in dry basalt. The absence of signals in dry basalt provides strong evidence that the piezoelectric effect and electrokinetic effect are dominant sources for precursory signals. Moreover we find that the amplitude of the precursory signals due to electrokinetic effect in saturated sandstone were as large as the coseismic signals. We propose that this signal is caused by accelerating evolution of dilatancy as cracks grow in the rock before rupture, resulting in water flow into the dilatant region with an electric current produced concurrently.

  20. Sulfide and sulfate saturation in hydrous silicate melts

    NASA Astrophysics Data System (ADS)

    Carroll, M. R.; Rutherford, M. J.

    1985-02-01

    A series of hydrothermal experiments was performed over a wide range of pressures, temperatures, oxygen fugacities, and melt FeO content, in order to examine the effects of physical changes on sulfur solubility in fractionated hydrous silicate melts. On the basis of the experimental results, it is concluded that upper crustal oxidation-reduction reactions and crystal fractionation processes may exert considerable influence on the amount of sulfur contained in magmas erupted at the surface. The application of the experimental results to investigations of volatile transport and volcanic degassing processes on the earth, Venus, and Mars is discussed

  1. Sulfide and sulfate saturation in hydrous silicate melts

    NASA Technical Reports Server (NTRS)

    Carroll, M. R.; Rutherford, M. J.

    1985-01-01

    A series of hydrothermal experiments was performed over a wide range of pressures, temperatures, oxygen fugacities, and melt FeO content, in order to examine the effects of physical changes on sulfur solubility in fractionated hydrous silicate melts. On the basis of the experimental results, it is concluded that upper crustal oxidation-reduction reactions and crystal fractionation processes may exert considerable influence on the amount of sulfur contained in magmas erupted at the surface. The application of the experimental results to investigations of volatile transport and volcanic degassing processes on the earth, Venus, and Mars is discussed

  2. The basalts of Mare Frigoris

    NASA Astrophysics Data System (ADS)

    Kramer, G. Y.; Jaiswal, B.; Hawke, B. R.; Öhman, T.; Giguere, T. A.; Johnson, K.

    2015-10-01

    This paper discusses the methodology and results of a detailed investigation of Mare Frigoris using remote sensing data from Clementine, Lunar Prospector, and Lunar Reconnaissance Orbiter, with the objective of mapping and characterizing the compositions and eruptive history of its volcanic units. With the exception of two units in the west, Mare Frigoris and Lacus Mortis are filled with basalts having low-TiO2 to very low TiO2, low-FeO, and high-Al2O3 abundances. These compositions indicate that most of the basalts in Frigoris are high-Al basalts—a potentially undersampled, yet important group in the lunar sample collection for its clues about the heterogeneity of the lunar mantle. Thorium abundances of most of the mare basalts in Frigoris are also low, although much of the mare surface appears elevated due to contamination from impact gardening with the surrounding high-Th Imbrium ejecta. There are, however, a few regional thorium anomalies that are coincident with cryptomare units in the east, the two youngest mare basalt units, and some of the scattered pyroclastic deposits and volcanic constructs. In addition, Mare Frigoris lies directly over the northern extent of the major conduit for a magma plumbing system that fed many of the basalts that filled Oceanus Procellarum, as interpreted by Andrews-Hanna et al. (2014) using data from the Gravity Recovery and Interior Laboratory mission. The relationship between this deep-reaching magma conduit and the largest extent of high-Al basalts on the Moon makes Mare Frigoris an intriguing location for further investigation of the lunar mantle.

  3. A model composition of the basaltic achondrite planetoid

    NASA Astrophysics Data System (ADS)

    Boesenberg, Joseph S.; Delaney, Jeremy S.

    1997-08-01

    The basaltic achondrites, eucrites, diogenites, and howardites have compositions on a common oxygen isotope mass fractionation line and probably formed from a chondritic precursor also lying on that same line. No chondritic meteorite group has the same isotopic signature as the basaltic achondrites, so the oxygen isotope ratios of several known chondritic groups were used to construct a two component mixing model for the composition of the precursor. This model does not provide a unique solution, as several mixtures of ordinary and carbonaceous precursors will satisfy the isotopic constraints. The FeMnMg abundances of the precursors and of the eucrites were used to provide an additional constraint. The precursor composition selected for study is a mixture of 70% (wt) H-chondrite with 30% (wt) CM-chondrtte. This mixture generates a slightly FeO-rich silicate precursor that, after reduction and separation of an iron + sulfide core, is compatible with the mantle of the basaltic achondrite planetoid (BAP) having a similar composition to that modeled by Dreibus and Wänke (1980). Partial melting experiments of this H-CM precursor composition suggest that eucritic magmas could be formed in such a mantle. These experiments also suggest that the mantle must have experienced metal loss to constrain the Fe/Mn ratios and probably significant olivine fractionation as well. Diogenite precursors may also be generated in this mantle composition as FeO reduction and olivine fractionation lead to the formation of SiO 2 enriched compositions from which diogenite source magmas may be extracted. If mixing of material from two very distinct chondritic reservoirs (H and CM-chondrites) is realistic, then an asteroid scale mixing process is needed to generate the achondrite precursor. Large impact events would provide a plausible method for mixing material from reservoirs with quite different oxygen isotope characteristics to assemble the basaltic achondrite planetoid.

  4. Melt migration in basalt columns driven by crystallization-induced pressure gradients.

    PubMed

    Mattsson, Hannes B; Caricchi, Luca; Almqvist, Bjarne S G; Caddick, Mark J; Bosshard, Sonja A; Hetényi, György; Hirt, Ann M

    2011-01-01

    The structure of columnar-jointed lava flows and intrusions has fascinated people for centuries and numerous hypotheses on the mechanisms of formation of columnar jointing have been proposed. In cross-section, weakly developed semicircular internal structures are a near ubiquitous feature of basalt columns. Here we propose a melt-migration model, driven by crystallization and a coeval specific volume decrease inside cooling and solidifying columns, which can explain the observed macroscopic features in columnar-jointed basalts. We study basalts from Hrepphólar (Iceland), combining macroscopic observations, detailed petrography, thermodynamic and rheological modelling of crystallization sequences, and Anisotropy of Magnetic Susceptibility (AMS) of late crystallizing phases (that is, titanomagnetite). These are all consistent with our proposed model, which also suggests that melt-migration features are more likely to develop in certain evolved basaltic lava flows (with early saturation of titanomagnetite), and that the redistribution of melt within individual columns can modify cooling processes.

  5. Radiation shielding concrete made of Basalt aggregates.

    PubMed

    Alhajali, S; Yousef, S; Kanbour, M; Naoum, B

    2013-04-01

    In spite of the fact that Basalt is a widespread type of rock, there is very little available information on using it as aggregates for concrete radiation shielding. This paper investigates the possibility of using Basalt for the aforementioned purpose. The results have shown that Basalt could be used successfully for preparing radiation shielding concrete, but some attention should be paid to the choice of the suitable types of Basalt and for the neutron activation problem that could arise in the concrete shield.

  6. Temperature dependence of basalt weathering

    NASA Astrophysics Data System (ADS)

    Li, Gaojun; Hartmann, Jens; Derry, Louis A.; West, A. Joshua; You, Chen-Feng; Long, Xiaoyong; Zhan, Tao; Li, Laifeng; Li, Gen; Qiu, Wenhong; Li, Tao; Liu, Lianwen; Chen, Yang; Ji, Junfeng; Zhao, Liang; Chen, Jun

    2016-06-01

    The homeostatic balance of Earth's long-term carbon cycle and the equable state of Earth's climate are maintained by negative feedbacks between the levels of atmospheric CO2 and the chemical weathering rate of silicate rocks. Though clearly demonstrated by well-controlled laboratory dissolution experiments, the temperature dependence of silicate weathering rates, hypothesized to play a central role in these weathering feedbacks, has been difficult to quantify clearly in natural settings at landscape scale. By compiling data from basaltic catchments worldwide and considering only inactive volcanic fields (IVFs), here we show that the rate of CO2 consumption associated with the weathering of basaltic rocks is strongly correlated with mean annual temperature (MAT) as predicted by chemical kinetics. Relations between temperature and CO2 consumption rate for active volcanic fields (AVFs) are complicated by other factors such as eruption age, hydrothermal activity, and hydrological complexities. On the basis of this updated data compilation we are not able to distinguish whether or not there is a significant runoff control on basalt weathering rates. Nonetheless, the simple temperature control as observed in this global dataset implies that basalt weathering could be an effective mechanism for Earth to modulate long-term carbon cycle perturbations.

  7. Shock Experiments on Basalt - Ferric Sulfate Mixes at 21 GPa & 49 GPa and their Relevance to Martian Meteorite Impact Glasses

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Ross, D. K.; See, T. H.; Nyquist, L. E.; Sutton, S.; Asimow, P.

    2013-01-01

    Large abundance of Martian atmospheric gases and neutron-induced isotopic excesses as well as Rb-Sr isotopic variations determined in some impact glasses in basaltic shergottites (e.g., Shergotty #DBS, Zagami #H1 and EET79001 #27, #8 and #104) provide definitive evidence for the occurrence of a Martian regolith component in their constituent mineral assemblages. Some of these glass-es, known as gas-rich impact-melts (GRIM), contain numerous micron-sized iron sulfide blebs along with minor amounts of iron sulfate particulates. As these GRIM glasses contain a Martian regolith component and as iron sulfates (but not sulfides) are found to occur abundantly on the Mars surface, we suggested that the sulfide blebs in GRIMs were likely generated by shock-reduction of the parental iron sulfate bearing regolith material that had been incorporated into the cavities/crevices of basaltic host rock prior to the impact event on Mars. To test whether the sulfates could be reduced to sulfides by impact shock, we carried out laboratory shock experiments on a basalt plus ferric sulfate mixture at 49 GPa at the Caltech Shock Wave Laboratory and at 21 GPa at Johnson Space Center (JSC) Experimental Impact Laboratory. The experimental details and the preliminary results for the Caltech 49 GPa experiment were presented at LPSC last year. Here, we report the results for the 21 GPa experiment at JSC and compare these results to obtain further insight into the mechanism of the bleb formation in the GRIM glasses.

  8. Experimental study into the petrogenesis of crystal-rich basaltic to andesitic magmas at Arenal volcano

    NASA Astrophysics Data System (ADS)

    Parat, F.; Streck, M. J.; Holtz, F.; Almeev, R.

    2014-08-01

    Arenal volcano is nearly unique among arc volcanoes with its 42 year long (1968-2010) continuous, small-scale activity erupting compositionally monotonous basaltic andesites that also dominate the entire, ~7000 year long, eruptive history. Only mineral zoning records reveal that basaltic andesites are the result of complex, open-system processes deriving minerals from a variety of crystallization environments and including the episodic injections of basalt. The condition of the mafic input as well as the generation of crystal-rich basaltic andesites of the recent, 1968-2010, and earlier eruptions were addressed by an experimental study at 200 MPa, 900-1,050 °C, oxidizing and fluid-saturated conditions with various fluid compositions [H2O/(H2O + CO2) = 0.3-1]. Phase equilibria were determined using a phenocryst-poor (~3 vol%) Arenal-like basalt (50.5-wt% SiO2) from a nearby scoria cone containing olivine (Fo92), plagioclase (An86), clinopyroxene (Mg# = 82) and magnetite (Xulvö = 0.13). Experimental melts generally reproduce observed compositional trends among Arenal samples. Small differences between experimental melts and natural rocks can be explained by open-system processes. At low pressure (200 MPa), the mineral assemblage as well as the mineral compositions of the natural basalt were reproduced at 1,000 °C and high water activity. The residual melt at these conditions is basaltic andesitic (55 wt% SiO2) with 5 wt% H2O. The evolution to more evolved magmas observed at Arenal occurred under fluid-saturated conditions but variable fluid compositions. At 1,000 °C and 200 MPa, a decrease of water content by approximately 1 wt% induces significant changes of the mineral assemblage from olivine + clinopyroxene + plagioclase (5 wt% H2O in the melt) to clinopyroxene + plagioclase + orthopyroxene (4 wt% H2O in the melt). Both assemblages are observed in crystal-rich basalt (15 vol%) and basaltic andesites. Experimental data indicate that the lack of orthopyroxene

  9. Trace elements in ocean ridge basalts

    NASA Technical Reports Server (NTRS)

    Kay, R. W.; Hubbard, N. J.

    1978-01-01

    A study is made of the trace elements found in ocean ridge basalts. General assumptions regarding melting behavior, trace element fractionation, and alteration effects are presented. Data on the trace elements are grouped according to refractory lithophile elements, refractory siderophile elements, and volatile metals. Variations in ocean ridge basalt chemistry are noted both for regional and temporal characteristics. Ocean ridge basalts are compared to other terrestrial basalts, such as those having La/Yb ratios greater than those of chondrites, and those having La/Yb ratios less than those of chondrites. It is found that (1) as compared to solar or chondrite ratios, ocean ridge basalts have low ratios of large, highly-charged elements to smaller less highly-charged elements, (2) ocean ridge basalts exhibit low ratios of volatile to nonvolatile elements, and (3) the transition metals Cr through Zn in ocean ridge basalts are not fractionated more than a factor of 2 or 3 from the chondritic abundance ratios.

  10. Thioarsenates in sulfidic waters.

    PubMed

    Stauder, S; Raue, B; Sacher, F

    2005-08-15

    It has long been recognized that the formation of soluble arsenic sulfur complexes plays a key role for the mobility and toxicity of arsenic in sulfate-reducing environments. Knowledge of the exact arsenic species is essential to understand the behavior of arsenic in sulfidic aquifers and to develop remediation strategies. In the past, monomeric and trimeric thioarsenites were assumed to be the existing species in sulfidic systems. In this study, thioarsenates were identified by IC-ICP/MS in arsenite- and sulfide-containing solutions as well as in a reduced groundwater from a contaminated site. The unexpected finding of an oxidation of As(lll) to As(V) in thioarsenates in strongly reducing systems can be explained by the high affinity between As(Ill) and sulfur. In sulfide-containing solutions without oxidant, As(lll) therefore undergoes disproportionation to thioarsenates (As(V)) and elemental arsenic. It has previously been supposed that mobility as well as toxicity of arsenic increases if the redox state decreases. For sulfidic waters, the opposite is probably the case. Thus, the formation of thioarsenates could be used in connection with remediation strategies. Thioarsenates are highly sensitive to oxygen and pH. This is important for analytical procedures. A loss of soluble arsenic as well as a conversion to arsenite and arsenate may occur if water samples containing thioarsenates are analyzed with conventional methods.

  11. Sulfidation of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Levard, C.; Michel, F. M.; Brown, G. E.

    2010-12-01

    Rapid development of nanotechnologies that exploit the properties of silver nanoparticles (Ag-NPs) raises questions concerning the impact of Ag on the environment. Ag-NPs are currently among the most widely used in the nanotechnology industry and the amount released into the environment is expected to increase along with production (1). When present in geochemical systems, Ag-NPs may undergo a variety of changes due to varying redox, pH, and chemical conditions. Expected changes range from surface modification (e.g., oxidation, sulfidation, chloridation etc.) to complete dissolution and re-precipitation. In this context, the focus of our work is on understanding the behavior of synthetic Ag-NPs with different particle sizes under varying conditions relevant to the environment. Sulfidation of Ag-NPs is of particular interest since it among the processes most likely to occur in aqueous systems, in particular under reducing conditions. Three sizes of Ag-NPs coated with polyvinyl pyrrolidone were produced using the polyol process (2) (7 ±1; 20 ±4, and 40 ±9 nm). Batch solutions containing the different Ag-NPs were subsequently reacted with Na2S solutions of different concentrations. The sulfidation process was followed step-wise for 24 hours and the corrosion products formed were characterized by electron microscopy (TEM/SEM), diffraction (XRD), and photo-electron spectroscopy (XPS). Surface charge (pHPZC) of the products formed during this process was also measured, as were changes in solubility and reactivity. Based on experimental observations we infer that the sulfidation process is the result of dissolution-precipitation and find that: (i) acanthite (Ag2S) is formed as a corrosion product; (ii) Ag-NPs aggregation increased with sulfidation rate; (iii) pHPZC increases with the rate of sulfidation; and (iv) the solubility of the corrosion products formed from sulfidation appears lower than that of non-sulfidated Ag-NPs. We observe size-dependent differences in

  12. Banded sulfide-magnetite ores of Mauk copper massive sulfide deposit, Central Urals: Composition and genesis

    NASA Astrophysics Data System (ADS)

    Safina, N. P.; Maslennikov, V. V.; Maslennikova, S. P.; Kotlyarov, V. A.; Danyushevsky, L. V.; Large, R. R.; Blinov, I. A.

    2015-05-01

    The results of investigation of metamorphosed sulfide-magnetite ores from the Mauk deposit located within the Main Ural Fault at the junction of Tagil and Magnitogorsk massive sulfide zones are discussed. The ore-hosting sequence comprises metamorphic rocks formed from basalt, carbonaceous and carbonaceous-cherty siltstone, and lenticular serpentinized ultramafic bodies. The ores of the deposit are represented by banded varieties and less frequent breccia. The clastic origin of the banded ore is indicated by load casts at the bottom of sulfide beds, alternation of sulfide and barren beds, and the truncation of the growth zones of pyrite crystals. Pyrite, pyrrhotite, chalcopyrite, sphalerite, and magnetite are the major minerals of the banded ores. The internal structure of the listed minerals testifies to the deep metamorphic recrystallization of primary hydrothermal-sedimentary ores accompanied with deformation. Cubanite, pyrrhotite, mackinawite, greigite, and gold are enclosed in metacrysts of pyrite, magnetite, and chalcopyrite. The accessory minerals of the Pb-Bi-Te, Bi-Te, and Ag-Te systems as well as uraninite have been found at the Mauk deposit for the first time. Magnetite predominantly replaces pyrite and less frequently chalcopyrite, pyrrhotite, and gangue minerals. It was established that the major carriers of As and Co are crystals of metamorphic pyrite. Chalcopyrite is the major carrier of Zn, Sn, Te, Pb, Bi, and Ag. Admixture of Fe and Cu is typical of sphalerite, and Se and Ni are characteristic of pyrrhotite. Ti, V, Mn, Sb, As, Ba, and U are concentrated in magnetite. The banded ores of the Mauk deposit are suggested as having been transformed in several stages: diagenesis, anadiagenesis, epidiagenesis ( t < 300°C), and amphibolite facies metamorphism ( t > 500°C).

  13. Thermoluminescence dating of Hawaiian basalt

    USGS Publications Warehouse

    May, Rodd James

    1979-01-01

    The thermoluminescence (TL) properties of plagioclase separates from 11 independently dated alkalic basalts 4,500 years to 3.3 million years old and 17 tholeiitic basalts 16 years to 450,000 years old from the Hawaiian Islands were investigated for the purpose of developing a TL dating method for young volcanic rocks. Ratios of natural to artificial TL intensity, when normalized for natural radiation dose rates, were used to quantify the thermoluminescence response of individual samples for age-determination purposes. The TL ratios for the alkalic basalt plagioclase were found to increase with age at a predictable exponential rate that permits the use of the equation for the best-fit line through a plot of the TL ratios relative to known age as a TL age equation. The equation is applicable to rocks ranging in composition from basaltic andesite to trachyte over the age range from about 2,000 to at least 250,000 years before present (B.P.). The TL ages for samples older than 50,000 years have a calculated precision of less than :t 10 percent and a potential estimated accuracy relative to potassium-argon ages of approximately :t 10 percent. An attempt to develop a similar dating curve for the tholeiitic basalts was not as successful, primarily because the dose rates are on the average lower than those for the alkalic basalts by a factor of 6, resulting in lower TL intensities in the tholeiitic basalts for samples of equivalent age, and also because the age distribution of dated material is inadequate. The basic TL properties of the plagioclase from the two rock types are similar, however, and TL dating of tholeiitic basalts should eventually be feasible over the age range 10,000 to at least 200,000 years B.P. The average composition of the plagioclase separates from the alkalic basalts ranges from oligoclase to andesine; compositional variations within this range have no apparent effect on the TL ratios. The average composition of the plagioclase from the tholeiitic

  14. Flood basalts and extinction events

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.

    1993-01-01

    The largest known effusive eruptions during the Cenozoic and Mesozoic Eras, the voluminous flood basalts, have long been suspected as being associated with major extinctions of biotic species. Despite the possible errors attached to the dates in both time series of events, the significance level of the suspected correlation is found here to be 1 percent to 4 percent. Statistically, extinctions lag eruptions by a mean time interval that is indistinguishable from zero, being much less than the average residual derived from the correlation analysis. Oceanic flood basalts, however, must have had a different biological impact, which is still uncertain owing to the small number of known examples and differing physical factors. Although not all continental flood basalts can have produced major extinction events, the noncorrelating eruptions may have led to smaller marine extinction events that terminated at least some of the less catastrophically ending geologic stages. Consequently, the 26 Myr quasi-periodicity seen in major marine extinctions may be only a sampling effect, rather than a manifestation of underlying periodicity.

  15. SULFIDE METHOD PLUTONIUM SEPARATION

    DOEpatents

    Duffield, R.B.

    1958-08-12

    A process is described for the recovery of plutonium from neutron irradiated uranium solutions. Such a solution is first treated with a soluble sullide, causing precipitation of the plutoniunn and uraniunn values present, along with those impurities which form insoluble sulfides. The precipitate is then treated with a solution of carbonate ions, which will dissolve the uranium and plutonium present while the fission product sulfides remain unaffected. After separation from the residue, this solution may then be treated by any of the usual methods, such as formation of a lanthanum fluoride precipitate, to effect separation of plutoniunn from uranium.

  16. CO2-filled vesicles in mid-ocean basalt

    USGS Publications Warehouse

    Moore, J.G.; Batchelder, J.N.; Cunningham, C.G.

    1977-01-01

    Volatile-filled vesicles are present in minor amounts in all samples of mid-ocean basalt yet collected (and presumably erupted) down to depths of 4.8 km. When such vesicles are pierced in liquid under standard conditions, the volume expansion of the gas is 0.2 ?? 0.05 times the eruption pressure in bars or 20 ?? 5 times the eruption depth in km. Such expansion could be used as a measure of eruption depth. A variety of techniques: (1) vacuum crushing and gas chromatographic, freezing separation, and mass spectrographic analyses; (2) measurements of phase changes on a freezing microscope stage; (3) microscopic chemical and solubility observations; and (4) volume change measurements, all indicate that CO2 comprises more than 95% by volume of the vesicle gas in several submarine basalt samples from the Atlantic and Pacific. The CO2 held in vesicles is present in quantities about equal to or greater than that presumed to be dissolved in the glass (melt) and amounts to 400-900 ppm of the rock. The rigid temperature of the glass is 800-1000??C and increases for shallower samples. A sulfur gas was originally present in subordinate amounts in the vesicles, but has largely reacted with iron in the vesicle walls to produce sulfide spherules. ?? 1977.

  17. Effect of chlorine on near-liquidus phase equilibria of an Fe-Mg-rich tholeiitic basalt

    NASA Astrophysics Data System (ADS)

    Filiberto, Justin; Dasgupta, Rajdeep; Gross, Juliane; Treiman, Allan H.

    2014-07-01

    The importance of Cl in basalt petrogenesis has been recognized, yet constraints on its effect on liquidus crystallization of basalts are scarce. In order to quantify the role of Cl in basaltic systems, we have experimentally determined near-liquidus phase relations of a synthetic Fe-Mg-rich basalt, doped with 0.0-2.5 wt% dissolved Cl, at 0.7, 1.1, and 1.5 GPa. Results have been parameterized and compared with previous data from literature. The effect of Cl on mineral chemistry and liquidus depression is dependent on the starting basaltic composition. The liquidus depression measured for a SiO2-rich, Al2O3-poor basalt is smaller than that observed for a basaltic melt depleted in silica and enriched in FeOT and Al2O3. The effect of Cl on depression of the olivine-orthopyroxene-liquid multiple saturation pressure does not seem to vary with the starting composition of the basaltic liquid. This suggests that Cl may significantly promote the generation of silica-poor, Fe-Al-rich magmas in the Earth, Mars, and the Moon.

  18. Flood Basalts and Neoproterozoic Glaciation

    NASA Astrophysics Data System (ADS)

    Halverson, G. P.; Cox, G. M.; Kunzmann, M.; Strauss, J. V.; Macdonald, F. A.

    2014-12-01

    Large igneous provinces (LIPs), which are commonly associated with supercontinental break-up, are the product of the emplacement of >106 km3 of mafic rocks in less than a few million years. LIP magmatism, in particular continental flood basalt (CFB) volcanism, perturbs global climate on shorter time scales through the radiative effects of degassed SO2 and CO2. On longer time scales, CFBs alter climate through the effect of the high weatherabilty of mafic rocks (5-10 times greater than average continental crust) on global silicate weathering. A link between flood basalt weathering, Rodinia break-up, and Neoproterozoic snowball glaciation has been postulated. Here we present a new compilation of Nd isotope data on Neoproterozoic mudstones from Laurentia, Australia, and South China along with a new seawater strontium isotope record from well preserved carbonates that support this hypothesis. These datasets are consistent with an outsized role of basalt weathering on the global silicate weathering budget during the second half of the Tonian period (~850 to 725 Ma). Along with Os isotope data, they also suggest that an additional pulse of basalt weathering at the end of the Tonian may have initiated the Sturtian snowball glaciation. CFBs have relatively high concentrations of phosphorous. Hence, the drawdown in atmospheric CO2 required to trigger the Sturtian snowball Earth was likely accomplished through a combination of increased silicate weathering rates and enhanced biological productivity driven by greater nutrient supply to the oceans. CFBs were also the likely source of the iron in Neoproterozoic iron formation (IF), all significant occurrences of which are restricted to Sturtian-aged glacial successions. Dramatic declines in ɛNd following the Cryogenian snowball glaciations are mirrored by stepwise increases in 87Sr/86Sr, reflecting the scouring of the continents by global ice sheets. This continental resurfacing removed the extensive basalt carapace as well as

  19. Mineralogy and geochemistry of a sediment-hosted hydrothermal sulfide deposit from the Southern Trough of Guaymas Basin, Gulf of California

    NASA Astrophysics Data System (ADS)

    Koski, Randolph A.; Lonsdale, Peter F.; Shanks, Wayne C.; Berndt, Michael E.; Howe, Stephen S.

    1985-07-01

    Samples dredged from a 15-m-high hydrothermal mound atop the flat turbidite pond in the Southern Trough of Guaymas Basin consist of pyrrhotite-rich massive sulfide, barite, barite + calcite, talc, and opaline silica as well as substrate material composed of fossiliferous, clay-rich ooze. An 11-m-long sediment core taken near the dredge site shows increasing hydrothermal alteration with depth; anhydrite-filled fractures near the base of the core appear to be channels for hydrothermal discharge. Oxidation of the sulfide-rich samples to an assemblage of geothite, lepidocrocite, and amorphous Fe oxyhydroxide is ubiquitous. Compared to other massive sulfide deposits on sediment-starved oceanic ridges, the hydrothermal deposit dredged in Guaymas Basin has a high pyrrhotite/pyrite ratio, a low Zn sulfide and combined ore metal (Cu + Zn + Pb + Ag + Cd) content, and a greater abundance of sulfate, carbonate, and silicate phases. Venting hydrothermal solutions are alkaline with moderately high pH; high Ca, Ba, and SiO2 content; low ƒS2 and ƒo2; and very low transition metal content. Disequilibrium assemblages of pyrrhotite and sulfate minerals form during rapid mixing of this evolved vent fluid with ambient bottom waters at the discharge site. Talc is formed at a temperature near 270°C by mixing or entrainment of Mg-rich bottom water or pore fluid with upwelling hydrothermal fluid that is saturated with silica. Calcite may precipitate from the alkaline, Ca-rich fluid during degassing of CO2. The minimum temperature range for sulfide and nonsulfide deposition is approximately 190°-326°C. The composition of hydrothermal deposits, vent solutions, and altered sediment requires that circulating fluids evolve during deep penetration into the basaltic basement complex, further interaction with the organic-and carbonate-rich sediment pile, and near-surface mixing with ambient seawater. Although the stable assemblage albite-epidote-clinochlore present at depth in the sediment

  20. Characterization of a newly isolated strain Pseudomonas sp. C27 for sulfide oxidation: Reaction kinetics and stoichiometry

    PubMed Central

    Xu, Xi-Jun; Chen, Chuan; Guo, Hong-liang; Wang, Ai-jie; Ren, Nan-qi; Lee, Duu-Jong

    2016-01-01

    Sulfide biooxidation by the novel sulfide-oxidizing bacteria Pseudomonas sp. C27, which could perform autotrophic and heterotrophic denitrification in mixotrophic medium, was studied in batch and continuous systems. Pseudomonas sp. C27 was able to oxidize sulfide at concentrations as high as 17.66 mM. Sulfide biooxidation occurred in two distinct stages, one resulting in the formation of sulfur with nitrate reduction to nitrite, followed by thiosulfate formation with nitrite reduction to N2. The composition of end-products was greatly impacted by the ratio of sulfide to nitrate initial concentrations. At a ratio of 0.23, thiosulfate represented 100% of the reaction products, while only 30% with a ratio of 1.17. In the continuous bioreactor, complete removal of sulfide was observed at sulfide concentration as high as 9.38 mM. Overall sulfide removal efficiency decreased continuously upon further increases in influent sulfide concentrations. Based on the experimental data kinetic parameter values were determined. The value of maximum specific growth rate, half saturation constant, decay coefficient, maintenance coefficient and yield were to be 0.11 h−1, 0.68 mM sulfide, 0.11 h−1, 0.21 mg sulfide/mg biomass h and 0.43 mg biomass/mg sulfide, respectively, which were close to or comparable with those reported in literature by other researches. PMID:26864216

  1. Zinc sulfide liquefaction catalyst

    DOEpatents

    Garg, Diwakar

    1984-01-01

    A process for the liquefaction of carbonaceous material, such as coal, is set forth wherein coal is liquefied in a catalytic solvent refining reaction wherein an activated zinc sulfide catalyst is utilized which is activated by hydrogenation in a coal derived process solvent in the absence of coal.

  2. Petrogenesis of Luna 16 aluminous mare basalts

    NASA Technical Reports Server (NTRS)

    Ma, M.-S.; Schmitt, R. A.; Nielsen, R. L.; Taylor, G. J.; Warner, R. D.; Keil, K.

    1979-01-01

    Bulk compositions, petrology and mineralogy of Luna 16 aluminous mare basalt particles of less than 0.5 mm are described. The data rule out any close genetic relationships between Luna 16 and other major types of lunar mare basalts. Compared to high-Ti mare basalts, the Luna 16 basalts contain lower TiO2 and Ta and higher Al2O3 and REE abundances, suggesting that the Luna 16 source rocks crystallized later than (i.e. stratigraphically above) the ilmenite-bearing high-Ti basalt cumulate source rocks. The REE pattern for the Luna 16 basalts requires that the source material from which they were derived crystallized from a light REE enriched magma.

  3. Basaltic volcanism - The importance of planet size

    NASA Technical Reports Server (NTRS)

    Walker, D.; Stolper, E. M.; Hays, J. F.

    1979-01-01

    The volumetrically abundant basalts on the earth, its moon, and the eucrite parent planet all have chemical compositions that are controlled to a large extent by dry, low-pressure, crystal-liquid equilibria. Since this generalization is valid for these three planetary bodies, we infer that it may also apply to the other unsampled terrestrial planets. Other characteristics of basaltic volcanism show variations which appear to be related to planet size: the eruption temperatures, degrees of fractionation, and chemical variety of basalts and the endurance of basaltic volcanism all increase with planet size. Although the processes responsible for chemical differences between basalt suites are known, no simple systematization of the chemical differences between basalts from planet to planet has emerged.

  4. S-33 constraints on the seawater sulfate contribution in modern seafloor hydrothermal vent sulfides

    USGS Publications Warehouse

    Ono, Shuhei; Shanks, Wayne C.; Rouxel, O.J.; Rumble, D.

    2007-01-01

    Sulfide sulfur in mid-oceanic ridge hydrothermal vents is derived from leaching of basaltic-sulfide and seawater-derived sulfate that is reduced during high temperature water rock interaction. Conventional sulfur isotope studies, however, are inconclusive about the mass-balance between the two sources because 34S/32S ratios of vent fluid H2S and chimney sulfide minerals may reflect not only the mixing ratio but also isotope exchange between sulfate and sulfide. Here, we show that high-precision analysis of S-33 can provide a unique constraint because isotope mixing and isotope exchange result in different ??33S (?????33S-0.515 ??34S) values of up to 0.04??? even if ??34S values are identical. Detection of such small ??33S differences is technically feasible by using the SF6 dual-inlet mass-spectrometry protocol that has been improved to achieve a precision as good as 0.006??? (2??). Sulfide minerals (marcasite, pyrite, chalcopyrite, and sphalerite) and vent H2S collected from four active seafloor hydrothermal vent sites, East Pacific Rise (EPR) 9-10??N, 13??N, and 21??S and Mid-Atlantic Ridge (MAR) 37??N yield ??33S values ranging from -0.002 to 0.033 and ??34S from -0.5??? to 5.3???. The combined ??34S and ??33S systematics reveal that 73 to 89% of vent sulfides are derived from leaching from basaltic sulfide and only 11 to 27% from seawater-derived sulfate. Pyrite from EPR 13??N and marcasite from MAR 37??N are in isotope disequilibrium not only in ??34S but also in ??33S with respect to associated sphalerite and chalcopyrite, suggesting non-equilibrium sulfur isotope exchange between seawater sulfate and sulfide during pyrite precipitation. Seafloor hydrothermal vent sulfides are characterized by low ??33S values compared with biogenic sulfides, suggesting little or no contribution of sulfide from microbial sulfate reduction into hydrothermal sulfides at sediment-free mid-oceanic ridge systems. We conclude that 33S is an effective new tracer for interplay among

  5. Characterization of reference Umtanum and Cohassett basalt

    SciTech Connect

    Allen, C.C.; Johnston, R.G.; Strope, M.B.

    1985-02-01

    The Basalt Waste Isolation Project (BWIP) Materials Testing Group (MTG) provides large quantities of reference basalt for testing waste package materials under repository conditions, site sorption characteristics and other experimental purposes. This document describes the reference rock materials currently used in testing, namely entablature and colonnade basalt from the Umtanum and Cohassett flows. The data include sampling locations, bulk chemical composition, modal percentages of major phases, and the chemical and mineralogical compositions of these phases. 8 refs., 17 figs., 15 tabs.

  6. The Use of Basalt, Basalt Fibers and Modified Graphite for Nuclear Waste Repository - 12150

    SciTech Connect

    Gulik, V.I.; Biland, A.B.

    2012-07-01

    New materials enhancing the isolation of radioactive waste and spent nuclear fuel are continuously being developed.. Our research suggests that basalt-based materials, including basalt roving chopped basalt fiber strands, basalt composite rebar and materials based on modified graphite, could be used for enhancing radioactive waste isolation during the storage and disposal phases and maintaining it during a significant portion of the post-closure phase. The basalt vitrification process of nuclear waste is a viable alternative to glass vitrification. Basalt roving, chopped basalt fiber strands and basalt composite rebars can significantly increase the strength and safety characteristics of nuclear waste and spent nuclear fuel storages. Materials based on MG are optimal waterproofing materials for nuclear waste containers. (authors)

  7. Mare basalt magma source region and mare basalt magma genesis

    SciTech Connect

    Binder, A.B.

    1982-11-15

    Given the available data, we find that the wide range of mare basaltic material characteristics can be explained by a model in which: (1) The mare basalt magma source region lies between the crust-mantle boundary and a maximum depth of 200 km and consists of a relatively uniform peridotite containing 73--80% olivine, 11--14% pyroxene, 4--8% plagioclase, 0.2--9% ilmenite and 1--1.5% chromite. (2) The source region consists of two or more density-graded rhythmic bands, whose compositions grade from that of the very low TiO/sub 2/ magma source regions (0.2% ilmenite) to that of the very high TiO/sub 2/ magma source regions (9% ilmenite). These density-graded bands are proposed to have formed as co-crystallizing olivine, pyroxene, plagioclase, ilmenite, and chromite settled out of a convecting magma (which was also parental to the crust) in which these crystals were suspended. Since the settling rates of the different minerals were governed by Stoke's law, the heavier minerals settled out more rapidly and therefore earlier than the lighter minerals. Thus the crystal assemblages deposited nearest the descending side of each convection cell were enriched in heavy ilmenite and chromite with respect to lighter olivine and pyroxene and very much lighter plagioclase. The reverse being the case for those units deposited near the ascending sides of the convection cells.

  8. Subseafloor basalts as fungal habitats

    NASA Astrophysics Data System (ADS)

    Ivarsson, M.; Bengtson, S.

    2013-12-01

    The oceanic crust makes up the largest potential habitat for life on Earth, yet next to nothing is known about the abundance, diversity and ecology of its biosphere. Our understanding of the deep biosphere of subseafloor crust is, with a few exceptions, based on a fossil record. Surprisingly, a majority of the fossilized microorganisms have been interpreted or recently re-interpreted as remnants of fungi rather than prokaryotes. Even though this might be due to a bias in fossilization the presence of fungi in these settings can not be neglected. We have examined fossilized microorganisms in drilled basalt samples collected at the Emperor Seamounts in the Pacific Ocean. Synchrotron-radiation X-ray tomography microscopy (SRXTM) studies has revealed a complex morphology and internal structure that corresponds to characteristic fungal morphology. Chitin was detected in the fossilized hyphae, which is another strong argument in favour of a fungal interpretation. Chitin is absent in prokaryotes but a substantial constituent in fungal cell walls. The fungal colonies consist of both hyphae and yeast-like growth states as well as resting structures and possible fruit bodies, thus, the fungi exist in vital colonies in subseafloor basalts. The fungi have also been involved in extensive weathering of secondary mineralisations. In terrestrial environments fungi are known as an important geobiological agent that promotes mineral weathering and decomposition of organic matter, and they occur in vital symbiosis with other microorganisms. It is probable to assume that fungi would play a similar role in subseafloor basalts and have great impact on the ecology and on biogeochemical cycles in such environments.

  9. The effects of sulfide composition on the solubility of sulfur in coexisting silicate melts

    NASA Astrophysics Data System (ADS)

    Smythe, Duane; Wood, Bernard; Kiseeva, Ekaterina

    2016-04-01

    The extent to which sulfur dissolves in silicate melts saturated in an immiscible sulfide phase is a fundamental question in igneous petrology and plays a primary role in the generation of magmatic ore deposits, volcanic degassing and planetary differentiation. Terrestrial sulfide melts often contain over 20 weight percent Ni + Cu, however, most experimental studies investigating sulfur solubility in silicate melt have been primarily concerned with the effects of silicate melt composition, and pure FeS has been use as the immiscible sulfide melt (O'Neill and Mavrogenes, 2002; Li and Ripley, 2005). To investigation of the effects of sulfide composition, in addition to those of temperature, pressure and silicate melt composition, on sulfur solubility in silicate melts, we have carried out a series of experiments done at pressures between 1.5 and 3 GPa and temperatures from 1400 to 1800C over a range of compositions of both the silicate and sulfide melt. We find that the solubility of sulfur in silicate melts drops significantly with the substitution of Ni and Cu for Fe in the immiscible sulfide melt, decreasing by approximately 40% at mole fractions of NiS + Cu2S of 0.4. Combining our results with those from the previous studies investigating sulfur solubility in silicate melts we have also found that solubility increases with increasing temperature and decreases pressure. These results show that without considering the composition of the immiscible sulfide phase the sulfur content of silicate melts can be significantly overestimated. This may serve to explain the relatively low sulfur concentrations in MORB melts, which previous models predict to be undersaturated in a sulfide phase despite showing chemical and textural evidence for sulfide saturation. Li, C. & Ripley, E. M. (2005). Empirical equations to predict the sulfur content of mafic magmas at sulfide saturation and applications to magmatic sulfide deposits. Mineralium Deposita 40, 218-230. O'Neill, H. S. C

  10. CORE SATURATION BLOCKING OSCILLATOR

    DOEpatents

    Spinrad, R.J.

    1961-10-17

    A blocking oscillator which relies on core saturation regulation to control the output pulse width is described. In this arrangement an external magnetic loop is provided in which a saturable portion forms the core of a feedback transformer used with the thermionic or semi-conductor active element. A first stationary magnetic loop establishes a level of flux through the saturation portion of the loop. A second adjustable magnet moves the flux level to select a saturation point giving the desired output pulse width. (AEC)

  11. Modeling Central American basalts using the Arc Basalt Simulator

    NASA Astrophysics Data System (ADS)

    Feigenson, M.; Carr, M. J.

    2011-12-01

    We have used the Arc Basalt Simulator (ABS), developed by JI Kimura, to explore the conditions and components of melting beneath the Central American volcanic front. ABS is a comprehensive forward model that incorporates slab dehydration and melting and mantle wedge fluxing and melting using realistic P-T conditions and experimentally determined phase relations. We have applied ABS versions 3 and 4 to model representative magma types in Nicaragua, which span a broad geochemical range including proximal high- and low-Ti lavas in Nicaragua. Sr-Nd-Pb data require appropriate selection of previously identified sources, including: separate carbonate and hemipelagic sediments, DMM, an enriched mantle isotopically similar to the alkaline basalts of Yojoa, a Himu-influenced mantle derived from Galapagos material and altered oceanic crust (AOC) derived from both MORB and Galapagos seamounts. Following the dry solidus, the dominant arc basalts, exemplified by Cerro Negro lavas, can be generated at about 80-90 km where lawsonite and zoisite break down, releasing LILEs into a hydrous fluid that travels into the wedge. The fluid-triggered melting occurs just above the garnet stability field in the wedge to fit the HREEs. Below 90 Km, slab melting begins and the AOC component dominates, generating a fluid with little or no HFSE depletions, consistent with the unusual high-Ti lavas found in Nicaragua. However, the isotopic data require a much lower sediment input for the high-Ti lavas (consistent with 10Be results on the high-Ti lavas) and an enriched component for the AOC and/or mantle wedge. Following the wet solidus, fits to the Cerro Negro magma only occur in the absence of phengite in the AOC and with the presence of HFSE attracting minerals, rutile, zircon and allanite. The depth of the best fit is 135 km, consistent with current best estimates of the depth to the seismic zone beneath Cerro Negro. Below 150 km, the high-Ti lavas can be generated if the HFSE retaining

  12. Electrochemical behavior of silver sulfide

    SciTech Connect

    Drouven, B.U.E.

    1982-01-01

    The electrochemical behavior of silver sulfide in sulfuric acid as well as in nitric acid was studied using electrodes made from synthetic silver sulfide. The primary techniques used were potentiostatic, potentiodynamic, galvanostatic and corrosion cell experiments. The cathodic reaction of silver sulfide produces silver and hydrogen sulfide. This reaction mechanism is a sequential two step charge transfer involving a single electron in each step. Silver ions are produced from silver sulfide upon applying an anodic potential. The dissolution rate of silver sulfide can be so high that the formation of silver sulfate occurs which partially covers the silver sulfide surface and inhibits a further rate increase. The sulfur from the silver sulfide will be oxidized at low overpotentials to elemental sulfur; at high overpotentials, the oxidation to sulfate or bisulfate is observed. The results suggest that the catalysis of chalcopyrite by the addition of silver ions is caused by the formation and subsequent dissolution of silver sulfide leaving a porous layer behind. The understanding of the reaction mechanism of silver sulfide dissolution and its optimization will significantly improve the economic evaluation of industrial processes using the catalyzed leaching of chalcopyrite. The present knowledge of the catalysis indicates that other ions may be substituted for silver ions which would increase the feasibility of hydrometallurgical processes.

  13. Sulfide detoxification in plant mitochondria.

    PubMed

    Birke, Hannah; Hildebrandt, Tatjana M; Wirtz, Markus; Hell, Rüdiger

    2015-01-01

    In contrast to animals, which release the signal molecule sulfide in small amounts from cysteine and its derivates, phototrophic eukaryotes generate sulfide as an essential intermediate of the sulfur assimilation pathway. Additionally, iron-sulfur cluster turnover and cyanide detoxification might contribute to the release of sulfide in mitochondria. However, sulfide is a potent inhibitor of cytochrome c oxidase in mitochondria. Thus, efficient sulfide detoxification mechanisms are required in mitochondria to ensure adequate energy production and consequently survival of the plant cell. Two enzymes have been recently described to catalyze sulfide detoxification in mitochondria of Arabidopsis thaliana, O-acetylserine(thiol)lyase C (OAS-TL C), and the sulfur dioxygenase (SDO) ethylmalonic encephalopathy protein 1 (ETHE1). Biochemical characterization of sulfide producing and consuming enzymes in mitochondria of plants is fundamental to understand the regulatory network that enables mitochondrial sulfide homeostasis under nonstressed and stressed conditions. In this chapter, we provide established protocols to determine the activity of the sulfide releasing enzyme β-cyanoalanine synthase as well as sulfide-consuming enzymes OAS-TL and SDO. Additionally, we describe a reliable and efficient method to purify OAS-TL proteins from plant material.

  14. Geothermal hydrogen sulfide removal

    SciTech Connect

    Urban, P.

    1981-04-01

    UOP Sulfox technology successfully removed 500 ppM hydrogen sulfide from simulated mixed phase geothermal waters. The Sulfox process involves air oxidation of hydrogen sulfide using a fixed catalyst bed. The catalyst activity remained stable throughout the life of the program. The product stream composition was selected by controlling pH; low pH favored elemental sulfur, while high pH favored water soluble sulfate and thiosulfate. Operation with liquid water present assured full catalytic activity. Dissolved salts reduced catalyst activity somewhat. Application of Sulfox technology to geothermal waters resulted in a straightforward process. There were no requirements for auxiliary processes such as a chemical plant. Application of the process to various types of geothermal waters is discussed and plans for a field test pilot plant and a schedule for commercialization are outlined.

  15. PGE geochemical constraints on the origin of the Ni-Cu-PGE sulfide mineralization in the Suoi Cun intrusion, Cao Bang province, Northeastern Vietnam

    NASA Astrophysics Data System (ADS)

    Svetlitskaya, Tatyana V.; Tolstykh, Nadezhda D.; Izokh, Andrey E.; Thi, Phuong Ngo

    2015-04-01

    The Permian (266-262 Ma) Suoi Cun intrusion in the Song Hien Rift Zone (NE Vietnam) consists of a sulfide-bearing mafic-ultramafic unit and a sulfide-free mafic unit. The Cu-Ni-PGE mineralization is represented by disseminated sulfides throughout the sulfide-bearing unit containing ~0.5 wt.% Ni, ~0.05 wt.% Cu, and ~0.2 ppm PGE. The sulfide schlieren have a limited distribution and contain ~2.6 wt.% Ni, ~0.5 wt.% Cu, and ~2.6 ppm PGE. The Suoi Cun rocks containing disseminated sulfides display moderately fractionated mantle-normalized PGE patterns with positive Pd and negative Ru anomalies. In contrast, the sulfide schlieren show enrichment in Ru with lower contents of other PGE except Pd. The low Cu/Pd ratios (1,385-11,529) throughout the intrusion indicate that all sulfides were separated from a PGE-undepleted magma as a result of a single sulfide segregation event. We suggest that sulfides segregated from Mg-rich basaltic magmas in a deep-seated magma chamber due to crustal contamination with country rocks. Then, the sulfide liquid along with early crystallizing olivines and Cr-spinels were pushed out upwards into an upper magma chamber by new pulses of magma. Two processes were important for understanding the PGE distribution: 1) fractionation of the sulfide liquid gave rise to PGE distribution observed in the disseminated ore and, 2) the interaction of oxidized silicate melts with the sulfide liquid was the responsible for the low PGE contents in the sulfide schlieren due to PGE transfer from the oxidized sulfide liquid to the silicate melt.

  16. Silicate melt removal and sulfide liquid retention in ultramafic rocks of the Duke Island Complex, Southeastern Alaska

    NASA Astrophysics Data System (ADS)

    Stifter, Eric C.; Ripley, Edward M.; Li, Chusi

    2014-10-01

    Magmatic Ni-Cu-PGE sulfide mineralization occurs within olivine clinopyroxenite, hornblende-bearing clinopyroxenite, and magnetite-hornblende-rich rocks in the Ural-Alaskan-Type Duke Island Complex in Southeast Alaska. The addition of large amounts of sulfur from country rocks occurred during fractional crystallization of the parental magma when clinopyroxene was becoming a liquidus mineral. Textural interfaces between sulfide and silicate minerals are strongly interlobate, and differ significantly from net-textures that are developed in many Ni-Cu-PGE deposits. Sulfide-free olivine clinopyroxenite is an adcumulate; residual liquid was efficiently expelled from the accumulating crystal pile. A significant interstitial liquid component is observable only in the form of interstitial sulfide in the S-rich rocks. Rounded sulfide inclusions and blebby to vermicular sulfide-silicate intergrowths indicate that silicate crystallization occurred under conditions of sulfide saturation. The presence of dense sulfide liquid inhibited the growth of silicate minerals and led to the development of interlobate grain boundaries. Strong, localized wetting of sulfide liquids on crystallizing silicates, and downward percolation of sulfide liquid through a crystallizing mush may have contributed to the evolution of these textures. Residual silicate liquid was removed from the system due to a combination of buoyant advection and compaction, but dense sulfide liquid remained.

  17. Volcanogenic trace element volatiles in basalts

    SciTech Connect

    Jovanovic, S.; Reed, G.W. Jr.

    1984-03-01

    Br, Hg, As, Se, Sb, Zn, and Cu were measured in samples of mid-ocean ridge (MOR) and ocean island basalt. To assess sea-water effects glassy rinds and crystalline interiors of pillow basalts were measured as was subaerial glass from Kilauea volcano. Preliminary results are reported. 6 references, 3 figures. (ACR)

  18. Shock metamorphism of lunar and terrestrial basalts

    NASA Technical Reports Server (NTRS)

    Schaal, R. B.; Hoerz, F.

    1977-01-01

    Lonar Crater (India) basalt and lunar basalt 75035 were shock loaded under controlled laboratory conditions up to 1000 kbar, generally in a CO/CO2 (1:1) environment evacuated to 10 to the minus seventh power torr. The Kieffer et al. (1976) classification scheme of progressive shock metamorphism is found to apply to lunar basalts. The major shock features of the five classes that span the range 0 to 1000 kbar are described. Only three out of 152 basalt specimens show shock effects in their natural state as severe as Class 2 features. The scarcity of shocked basalt hand samples in contrast to the abundance of shock-produced agglutinates and homogeneous glass spheres in the lunar regolith indicates the dominant role of micrometeorite impact in the evolution of the lunar regolith. The overall glass content in asteroidal and Mercurian regoliths is considered.

  19. X-ray microspectroscopy of sulfur in basaltic glass inclusions. Inference on the volcanic sulfur emissions

    NASA Astrophysics Data System (ADS)

    Métrich, N.; Susini, J.; Galoisy, L.; Calas, G.; Bonnin-Mosbah, M.; Menez, B.

    2003-03-01

    It is commonly accepted that sulfur is carried out as sulfide (S^{II-}) or/and sulfate (S^{VI}) by Earth mantlederived melts, before being released as SO2 and/or H2S in volcanic emissions. By analyzing reference compounds and a selection of minute glass inclusions in olivine crystals using μXANES (X-ray Near Edge Structure) spectroscopy at the sulfur K-edge, we demonstrated the ubiquitous presence of sulfite (S^{IV}) in addition to sulfate (S^{VI}) in these rare inclusions representative of oxidized and water rich-basaltic magmas, prior to loss of sulfur and water. The sulfide (S^{II-}) when exists is minor. We proposed that sulfite (S^{IV}) acts as an intermediate, metastable species which results in partitioning of sulfur into the volcanic gas emissions.

  20. Gluon saturation in a saturated environment

    SciTech Connect

    Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan

    2011-07-15

    A bootstrap equation for self-quenched gluon shadowing leads to a reduced magnitude of broadening for partons propagating through a nucleus. Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. In nucleus-nucleus collisions all participating nucleons acquire enhanced gluon density at small x, which boosts further the saturation scale. Solution of the reciprocity equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q{sub sA}{sup 2}, in AA compared with pA collisions.

  1. Heterogeneity in titaniferous lunar basalts

    NASA Technical Reports Server (NTRS)

    Walker, D.; Longhi, J.; Hays, J. F.

    1976-01-01

    Small but real chemical differences exist between subsamples of fine-grained quench-textured titaniferous lunar basalts. The existence of different textural domains with different chemistries is thought to account for most of this variation. In addition to the textural domains, lunar sample 74275 has a population of olivine 'megacrysts' as well as dunite fragments. These materials are thought to be extraneous and to compromise the primary nature of 74275. Recognition of the small chemical variations present may aid in understanding some discrepancies in the experimental-petrology literature. However, these small variations have a distressing petrogenetic significance since they severely limit resolution in recognizing the number and depth of origin of primary magmas.

  2. Sulfide isotopic compositions in shergottites and ALH84001, and possible implications for life on Mars

    SciTech Connect

    Greenwood, J.P.; McSween, H.Y. Jr.; Riciputi, L.R.

    1997-10-01

    The shergottite and ALH84001 meteorites hold keys for understanding geologic and possibly biologic processes on Mars. Recently, it has been proposed that carbonates in ALH84001, and the Fe-sulfides they contain, are products of extraterrestrial biogenic activity. Here we report ion microprobe analyses of sulfides in shergottites and ALH84001. The sulfur isotope ratios of igneous pyrrhotites in shergottites (mean {delta}{sup 34}S{sub CDT}: Shergotty = -0.4{per_thousand}, Zagami = +2.7{per_thousand}, EETA79001A = 1.9{per_thousand}, EETA79001B = -1.7{per_thousand}, LEW88516 = -1.9{per_thousand}, QUE94201 = +0.8{per_thousand}) are similar to those of terrestrial ocean-floor basalts, suggesting that the sulfur isotopic composition of the Martian mantle may be similar to that of the mantle of the Earth. The sulfur isotopic systematics of ALH84001 sulfides are distinct from the shergottites. Measured sulfur isotope ratios of eight pyrite grains ({delta}{sup 34}S{sub CDT} = +2.0 to +7.3{per_thousand}) in crushed zones confirm previously reported analyses of isotopically heavy sulfides and are indistinguishable from an Fe-sulfide zone within a carbonate globule ({delta}{sup 34}S{sub CDT} = +6.0{per_thousand}). Analyses of synthesized, fine-grained mixtures of sulfide, carbonate, and magnetite indicate than the measured sulfur isotope ratio is independent of the presence of carbonate and magnetite in the sputtered volume, confirming the accuracy of the analysis of the fine-grained sulfide in the carbonate globule. Terrestrial biogenic sulfate reduction typically results in light isotopic enrichments. The similarity of {delta}{sup 34}S values of the sulfides in ALH84001 imply that the Fe-sulfide zones within ALH84001 carbonates are probably not the result of bacterial reduction of sulfate. 38 refs., 3 figs., 1 tab.

  3. Re-Os geochronology on sulfides from the Tudun Cu-Ni sulfide deposit, Eastern Tianshan, and its geological significance

    NASA Astrophysics Data System (ADS)

    Wang, Minfang; Wang, Wei; Gutzmer, Jens; Liu, Kun; Li, Chao; Michałak, Przemysław P.; Xia, Qinlin; Guo, Xiaonan

    2015-11-01

    The Tudun deposit is a medium-sized Cu-Ni sulfide deposit, located at the westernmost edge of the Huangshan-Jing'erquan Belt in the northern part of Eastern Tianshan, NW China. Sulfide separates including pentlandite, pyrrhotite and chalcopyrite from the Tudun deposit, contain Re, common Os and 187Os ranging from 40.46 to 201.2, 0.8048 to 6.246 and 0.1709 to 0.9977 ppb, respectively. They have very low 187Os/188Os ratios of 1.224-2.352. The sulfides yield a Re-Os isochron age of 270.0 ± 7.5 Ma (MSWD = 1.3), consistent within uncertainty with the SHRIMP zircon U-Pb age for the Tudun mafic intrusion (gabbro) of 280.0 ± 3.0 Ma. The calculated initial 187Os/188Os ratio is 0.533 ± 0.022, and γOs values range from 283 to 307, with a mean of 297, indicating significant crustal contamination of the parent melt prior to sulfide saturation. The Tudun deposit shares the same age and Re-Os isotopic compositions with other orthomagmatic Cu-Ni sulfide deposits in Huangshan-Jing'erquan Belt, suggesting that they have formed in Early Permian.

  4. The Mantle and Basalt-Crust Interaction Below the Mount Taylor Volcanic Field, New Mexico

    NASA Technical Reports Server (NTRS)

    Schrader, Christian M.; Crumpler, Larry S.; Schmidt, Marick E.

    2010-01-01

    The Mount Taylor Volcanic Field (MTVF) lies on the Jemez Lineament on the southeastern margin of the Colorado Plateau. The field is centered on the Mt. Taylor composite volcano and includes Mesa Chivato to the NE and Grants Ridge to the WSW. MTVF magmatism spans approximately 3.8-1.5 Ma (K-Ar). Magmas are dominantly alkaline with mafic compositions ranging from basanite to hy-basalt and felsic compositions ranging from ne-trachyte to rhyolite. We are investigating the state of the mantle and the spatial and temporal variation in basalt-crustal interaction below the MTVF by examining mantle xenoliths and basalts in the context of new mapping and future Ar-Ar dating. The earliest dated magmatism in the field is a basanite flow south of Mt. Taylor. Mantle xenolith-bearing alkali basalts and basanites occur on Mesa Chivato and in the region of Mt. Taylor, though most basalts are peripheral to the main cone. Xenolith-bearing magmatism persists at least into the early stages of conebuilding. Preliminary examination of the mantle xenolith suite suggests it is dominantly lherzolitic but contains likely examples of both melt-depleted (harzburgitic) and melt-enriched (clinopyroxenitic) mantle. There are aphyric and crystal-poor hawaiites, some of which are hy-normative, on and near Mt. Taylor, but many of the more evolved MTVF basalts show evidence of complex histories. Mt. Taylor basalts higher in the cone-building sequence contain >40% zoned plagioclase pheno- and megacrysts. Other basalts peripheral to Mt. Taylor and at Grants Ridge contain clinopyroxene and plagioclase megacrysts and cumulate-textured xenoliths, suggesting they interacted with lower crustal cumulates. Among the questions we are addressing: What was the chemical and thermal state of the mantle recorded by the basaltic suites and xenoliths and how did it change with time? Are multiple parental basalts (Si-saturated vs. undersaturated) represented and, if so, what changes in the mantle or in the tectonic

  5. The solubility of sulfur in high-TiO2 mare basalts

    NASA Technical Reports Server (NTRS)

    Danckwerth, P. A.; Hess, P. C.; Rutherford, M. J.

    1979-01-01

    The present paper deals with an experimental investigation of the solubility of sulfur of the high-TiO2 mare basalt 74275 at 1 atm, 1250 C. The data indicate that at saturation, 74275 is capable of dissolving 3400 ppm sulfur at 10 to 15 degrees below its liquidus. The analyzed samples of 74275 show sulfur contents of 1650 ppm S, which indicates that 74275 was 50% undersaturated at the time of eruption.

  6. Mineralization of Basalts in the CO2-H2O-H2S System

    SciTech Connect

    Schaef, Herbert T.; McGrail, B. Peter; Owen, Antionette T.; Arey, Bruce W.

    2013-05-10

    Basalt samples representing five different formations were immersed in water equilibrated with supercritical carbon dioxide containing 1% hydrogen sulfide (H2S) at reservoir conditions (100 bar, 90°C) for up to 3.5 years. Surface coatings in the form of pyrite and metal cation substituted carbonates were identified as reaction products associated with all five basalts. In some cases, high pressure tests contained excess H2S, which produced the most corroded basalts and largest amount of secondary products. In comparison, tests containing limited amounts of H2S appeared least reacted with significantly less concentrations of reaction products. In all cases, pyrite appeared to precede carbonation, and in some instances, was observed in the absence of carbonation such as in cracks, fractures, and within the porous glassy mesostasis. Armoring reactions from pyrite surface coatings observed in earlier shorter duration tests were found to be temporary with carbonate mineralization observed with all the basalts tested in these long duration experiments. Geochemical simulations conducted with the geochemical code EQ3/6 accurately predicted early pyrite precipitation followed by formation of carbonates. Reactivity with H2S was correlated with measured Fe(II)/Fe(III) ratios in the basalts with more facile pyrite formation occurring with basalts containing more Fe(III) phases. These experimental and modeling results confirm potential for long term sequestration of acid gas mixtures in continental flood basalt formations.

  7. Sedimentary-hosted polymetallic massive sulfide deposits of the Kebrit and Shaban Deeps, Red Sea

    NASA Astrophysics Data System (ADS)

    Blum, N.; Puchelt, H.

    1991-07-01

    Massive sulfides recovered from the Kebrit Deep carbonaceous sedimentary succession represent black smoker fragments, novel to any Red Sea brine pool deposit. Chimneys, which were also observed in situ near the seawater/brine interface of the Kebrit Deep pool, are primarily comprised of Fe-, Zn- and Pb-bearing phases, and are often tar and asphalt impregnated. Cu-sulfides are virtually absent from parageneses, contrasting rift-related smoker and Red Sea metalliferous sediment deposits. Concentration of nickel in discrete bravoite points to a basalt/seawater leaching process as a source for most metals. The sedimentary package, which probably hosts Cu-mineralization in lower stockworks of the smoker deposit, is considered the major source of lead. Prevention of boiling of hydrothermal fluids, passing through a succession of organic-rich carbonate and clay horizons prior to discharge, is essential for smoker formation. Shaban Deep sedimentary-hosted massive sulfides are less frequent, with pyrite being the dominant ore mineral. Sulfur isotope data indicate both high temperature inorganic as well as biogenic sulfate (seawater and/or evaporite) reduction in sulfide-forming processes. Cogenetic sulfates formed from residual, bacteriogenically reduced seawater sulfate. Rather low sulfide/sulfate precipitation temperatures of 110 130 °C for the Kebrit brine pool and 100 °C for Shaban Deep massive sulfides are evident.

  8. Basalt CO2 Sequestration: Using Wireline Logs to Identify Subsurface Continental Flood Basalt Lithofacies

    NASA Astrophysics Data System (ADS)

    Sullivan, E. C.; Finn, S.; Davis, K. N.; Segovia, A. I.

    2010-12-01

    The flows of the Miocene Columbia River Basalt Group (CRBG) of the northwest United States are an important example of reactive flood basalts that are attractive targets for sequestration of anthropogenic carbon dioxide. Brecciated flow tops and dense flow interiors form layered regional aquifer systems in the Columbia Basin that have the potential to sequester gigatons of supercritical CO2 where they contain non-potable water and are at depths of greater than 800m. The demonstrated chemical reactivity of these continental flood basalts with supercritical CO2 in laboratory experiments suggests that part of the sequestered CO2 will be permanently entombed as carbonate minerals. Here we report on the use of conventional wire-line log data, along with full waveform sonic and resistivity-based image logs to identify subsurface basalt stratigraphy and lithofacies relevant to CO2 sequestration. We compare borehole data from the 2009 Big Sky Carbon Sequestration Partnership basalt pilot well near Wallula, Washington U.S.A. with regional outcrop analogs to determine patterns for recognizing basalt lithofacies in the subsurface. We examine quick-look techniques recently proposed for hydrocarbon exploration in basalt terranes and show that rescaled shear and compressional sonic log curves, which reflect changes in bulk modulus, appear to provide a robust tool for the identification of subsurface CRBG basalt lithofacies Resistivity-based Image Log of Vesicular Basalt and Fractures From the Wallula Basalt Pilot Well

  9. Hydrogen sulfide intoxication.

    PubMed

    Guidotti, Tee L

    2015-01-01

    Hydrogen sulfide (H2S) is a hazard primarily in the oil and gas industry, agriculture, sewage and animal waste handling, construction (asphalt operations and disturbing marshy terrain), and other settings where organic material decomposes under reducing conditions, and in geothermal operations. It is an insoluble gas, heavier than air, with a very low odor threshold and high toxicity, driven by concentration more than duration of exposure. Toxicity presents in a unique, reliable, and characteristic toxidrome consisting, in ascending order of exposure, of mucosal irritation, especially of the eye ("gas eye"), olfactory paralysis (not to be confused with olfactory fatigue), sudden but reversible loss of consciousness ("knockdown"), pulmonary edema (with an unusually favorable prognosis), and death (probably with apnea contributing). The risk of chronic neurcognitive changes is controversial, with the best evidence at high exposure levels and after knockdowns, which are frequently accompanied by head injury or oxygen deprivation. Treatment cannot be initiated promptly in the prehospital phase, and currently rests primarily on supportive care, hyperbaric oxygen, and nitrite administration. The mechanism of action for sublethal neurotoxicity and knockdown is clearly not inhibition of cytochrome oxidase c, as generally assumed, although this may play a role in overwhelming exposures. High levels of endogenous sulfide are found in the brain, presumably relating to the function of hydrogen sulfide as a gaseous neurotransmitter and immunomodulator. Prevention requires control of exposure and rigorous training to stop doomed rescue attempts attempted without self-contained breathing apparatus, especially in confined spaces, and in sudden release in the oil and gas sector, which result in multiple avoidable deaths. PMID:26563786

  10. Petrogenesis of Mt. Baker Basalts and Andesites: Constraints From Mineral Chemistry and Phase Equilibria

    NASA Astrophysics Data System (ADS)

    Mullen, E.; McCallum, I. S.

    2009-12-01

    ; however, the two methods do not give consistent results. The water content and redox state of the basalts are inversely correlated, inconsistent with data from andesites that show the reverse correlation. Using published experimental data and the BATCH algorithm (Longhi, 2002) we constructed an array of phase diagrams in the multi-component basalt system relevant to arc basalts and andesites ranging from 0 to 3 GPa and variable water contents. Projections of Mt. Baker lava compositions (corrected for loss or gain of olivine and plag where appropriate) on these diagrams reveal: (1) with the exception of Sulphur Cr., primary basaltic compositions equilibrated with depleted hydrous mantle harzburgite/lherzolite at pressures from 1 to 1.5 GPa, coincident with the crust-mantle boundary in the Mt. Baker region, (2) except for Sulphur Cr., melt fractions were >10%; Sulphur Cr. basalt is alkalic and formed by smaller degrees of partial melting comparable to basalts from the northern Garibaldi belt, (3) evidence for shallow fractionation of basalts (5-10 km), (4) Mt. Baker andesites delineate a low pressure fractionation trend coincident with the 0.2 GPa, water-saturated, oliv+cpx+plag and cpx+amph+plag cotectics (Sisson and Grove, 1993, Grove et al., 2003).

  11. Experimental Evidence for Polybaric Intracrustal Differentiation of Primitive Arc Basalt beneath St. Vincent, Lesser Antilles

    NASA Astrophysics Data System (ADS)

    Blundy, Jon; Melekhova, Lena; Robertson, Richard

    2014-05-01

    We present experimental phase equilibria for a primitive, high-Mg basalt from St. Vincent, Lesser Antilles. Experimental details were presented in Melekhova et al (Nature Geosci, 2013); the objective here is to compare experimental phase compositions to those of erupted lavas and cumulates from St. Vincent. Starting material with 4.5 wt% H2O is multiply-saturated with a lherzolite assemblage at 1.3 GPa and 1180 ° C, consistent with mantle wedge derivation. Experimental glasses from our study, in addition to those of Pichavant et al (GCA, 2002) and Pichavant & Macdonald (CMP 2007) on a similar high-Mg basalt, encompass a compositional range from high-magnesian basalt to dacite, with a systematic dependence on H2O content, temperature and pressure. We are able to match the glasses from individual experiments to different lava types, so as to constrain the differentiation depths at which these magmas could be generated from a high-Mg parent, as follows: Composition wt% H2OP (GPa) T (° C) High-Mg basalt 3.9-4.8 1.45-1.751180-1200 Low-Mg basalt 2.3-4.5 1.0-1.3 1065-1150 High alumina basalt 3.0-4.5 0.4 1050-1080 Basaltic andesite 0.6-4.5 0.7-1.0 1050-1130 Andesite 0.6 1.0 1060-1080 The fact that St. Vincent andesites (and some basaltic andesites) appear to derive from a low-H2O (0.6 wt%) parent suggest that they are products of partial melting of older, high-Mg gabbroic rocks, as 0.6 wt% H2O is approximately the amount that can be stored in amphibole-bearing gabbros. The higher H2O contents of parents for the other lava compositions is consistent with derivation by crystallization of basalts with H2O contents that accord with those of olivine-hosted melt inclusions from St. Vincent (Bouvier et al, J Petrol, 2008). The generation of evolved melts both by basalt crystallization and gabbro melting is consistent with the hot zone concept of Annen et al (J Petrol, 2006) wherein repeated intrusion of mantle-derived basalt simultaneously crystallize by cooling and melt

  12. Sulfide capacity of CaO-CaF2-SiO2 slags

    NASA Astrophysics Data System (ADS)

    Susaki, Katsujiro; Maeda, Masafumi; Sano, Nobuo

    1990-02-01

    The sulfide capacity C S 2- = (pct S2-) · ( P O 2/ P S 2)1/2) of CaO-CaF2-SiO2 slags saturated with CaO, 3CaO · SiO2 or 2CaOSiO2 was determined at 1200 °C, 1250 °C, 1300 °C, and 1350 °C by equilibrating molten slag, molten silver, and CO-CO2 gas mixtures. Higher sulfide capacities were obtained for CaO-saturated slags. A drastic decrease was observed in those values when the ratio pct CaO/pct SiO2 is less than 2. The sulfur partition between carbon-saturated iron melts and presently investigated slags was calculated by using the sulfide capacities obtained and the activity coefficient of sulfur in carbon-saturated iron, which was also experimentally determined. For slags saturated with CaO, partitions of sulfur as high as 10,000 were obtained at 1300 °C and 1350 °C. Correlations between the sulfide capacity and other basicity indexes such as carbonate capacity and theoretical optical basicity were also discussed.

  13. Composition and origin of basaltic magma of the Hawaiian Islands

    USGS Publications Warehouse

    Powers, H.A.

    1955-01-01

    Silica-saturated basaltic magma is the source of the voluminous lava flows, erupted frequently and rapidly in the primitive shield-building stage of activity, that form the bulk of each Hawaiian volcano. This magma may be available in batches that differ slightly in free silica content from batch to batch both at the same and at different volcanoes; differentiation by fractionation of olivine does not occur within this primitive magma. Silica-deficient basaltic magma, enriched in alkali, is the source of commonly porphyritic lava flows erupted less frequently and in relatively negligible volume during a declining and decadent stage of activity at some Hawaiian volcanoes. Differentiation by fractionation of olivine, plagioclase and augite is evident among these lavas, but does not account for the silica deficiency or the alkali enrichment. Most of the data of Hawaiian volcanism and petrology can be explained by a hypothesis that batches of magma are melted from crystalline paridotite by a recurrent process (distortion of the equatorial bulge by forced and free nutational stresses) that accomplishes the melting only of the plagioclase and pyroxene component but not the excess olivine and more refractory components within a zone of fixed and limited depth. Eruption exhausts the supply of meltable magma under a given locality and, in the absence of more violent melting processes, leaves a stratum of crystalline refractory components. ?? 1955.

  14. Anaglyph: Basalt Cliffs, Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Basalt cliffs along the northwest edge of the Meseta de Somuncura plateau near Sierra Colorada, Argentina show an unusual and striking pattern of erosion. Stereoscopic observation helps to clarify the landform changing processes active here. Many of the cliffs appear to be rock staircases that have the same color as the plateau's basaltic cap rock. Are these the edges of lower layers in the basalt or are they a train of slivers that are breaking off from, then sliding downslope and away from, the cap rock. They appear to be the latter. Close inspection shows that each stair step is too laterally irregular to be a continuous sheet of bedrock like the cap rock. Also, the steps are not flat but instead are little ridges, as one might expect from broken, tilted, and sliding slices of the cap rock. Stream erosion has cut some gullies into the cliffs and vegetation (appears bright in this infrared image) shows that water springs from and flows down some channels, but land sliding is clearly a major agent of erosion here.

    This anaglyph was generated by first draping a Landsat Thematic Mapper image over a topographic map from the Shuttle Radar Topography Mission, then producing the two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and the right eye with a blue filter.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7 Thematic Mapper image used here was provided to the SRTM project by the United States Geological Survey, Earth Resources Observation Systems (EROS) Data Center,Sioux Falls, South Dakota.

    Elevation data used in this

  15. Basaltic Crater in Color IR

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released August 6, 2004 This image shows two representations of the same infra-red image near Nili Fosse in the the Isidis region of Mars. On the left is a grayscale image showing surface temperature, and on the right is a false-color composite made from 3 individual THEMIS bands. The false-color image is colorized using a technique called decorrelation stretch (DCS), which emphasizes the spectral differences between the bands to highlight compositional variations. In many cases craters trap sand in their topographic depressions, interrupting the sand's migration across the Martian surface. This image is particularly interesting because there appears to be more than 1 type of sand in the bottom of this crater and in the hummocky terrain near the bottom of the image. The pink/magenta areas are characteristic of a basaltic composition, but there are also orange areas that are likely caused by the presence of andesite. These two compositions, basalt and andesite, are some of the most common found on Mars.

    Image information: IR instrument. Latitude 24, Longitude 80.7 East (297.3 West). 100 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip

  16. Relating sulfide mineral zonation and trace element chemistry to subsurface processes in the Reykjanes geothermal system, Iceland

    NASA Astrophysics Data System (ADS)

    Libbey, R. B.; Williams-Jones, A. E.

    2016-01-01

    The nature and distribution of sulfide minerals and their trace element chemistry in the seawater-dominated Reykjanes geothermal system was determined through the study of cuttings and core from wells that intersect different regions of the hydrothermal cell, from the near surface to depths of > 3000 m. The observed sulfide mineral zonation and trace element enrichment correlate well with the present-day thermal structure of the system. Isocubanite and pyrrhotite are confined to the deep, low permeability regions, whereas an assemblage of chalcopyrite and pyrite predominates in the main convective upflow path. The presence of marcasite in the uppermost regions of the system reflects weakly acidic conditions (pH < 5) marginal to the upflow, where outflow and downward percolating fluids have dissolved deeply exsolved CO2. The presence of "chalcopyrite disease" in sphalerite may be an indication that the system is experiencing a heating trend, following the logic of "zone-refining" in volcanogenic massive sulfide systems. Sulfide sulfur at all analyzed depths in the Reykjanes geothermal system was derived from a mixture of basaltic and reduced seawater sources. Petrographic evidence suggests that seawater-derived hydrothermal fluids have altered primary igneous sulfides in the host rocks, a process that has been proposed as a major control of aqueous sulfide production in mid-ocean ridge environments. Calculations show that igneous sulfides in the host basalts likely account for less than 5% of the total available ore metal budget in the system, however, their contribution to fluid metal budgets is probably significant because of their relatively high solubility. The processes documented by this study are likely analogous to those operating in the feeder and deep reaction zones of mid-ocean ridge seafloor hydrothermal systems. The results show that sulfide mineral zonation and trace element chemistry vary as a function of physicochemical parameters that are relevant

  17. Field method for sulfide determination

    SciTech Connect

    Wilson, B L; Schwarser, R R; Chukwuenye, C O

    1982-01-01

    A simple and rapid method was developed for determining the total sulfide concentration in water in the field. Direct measurements were made using a silver/sulfide ion selective electrode in conjunction with a double junction reference electrode connected to an Orion Model 407A/F Specific Ion Meter. The method also made use of a sulfide anti-oxidant buffer (SAOB II) which consists of ascorbic acid, sodium hydroxide, and disodium EDTA. Preweighed sodium sulfide crystals were sealed in air tight plastic volumetric flasks which were used in standardization process in the field. Field standards were prepared by adding SAOB II to the flask containing the sulfide crystals and diluting it to the mark with deionized deaerated water. Serial dilutions of the standards were used to prepare standards of lower concentrations. Concentrations as low as 6 ppB were obtained on lake samples with a reproducibility better than +- 10%.

  18. Chalcophile element (Ni, Cu, PGE, and Au) variations in the Tamarack magmatic sulfide deposit in the Midcontinent Rift System: implications for dynamic ore-forming processes

    NASA Astrophysics Data System (ADS)

    Taranovic, Valentina; Ripley, Edward M.; Li, Chusi; Rossell, Dean

    2016-03-01

    correlation between Pt and Pd, and between individual IPGE. At a given Pt or Pd content, however, the semi-massive sulfide ores have higher IPGE contents than the disseminated sulfide samples. Modeling results show that the variations in PGE tenors (metals in recalculated 100 % sulfide) in the Tamarack magmatic sulfide deposit are mainly controlled by variable R factors (magma/sulfide-liquid mass ratios) during sulfide-liquid segregation and subsequent monosulfide solid solution (MSS) fractionation during cooling. The initial contents of Ir, Pt, and Pd in the parental magma, estimated from the metal tenors of the disseminated sulfides, are 0.2, 2, and 1.8 ppb, respectively, which are ˜1/5 of the values for the PGE-undepleted primitive basalts of the Midcontinent Rift System. The variations of PGE tenors in the semi-massive and massive sulfide ores can be explained by MSS fractional crystallization from sulfide liquids. Extreme variations in the PGE contents of the massive sulfides may also in part reflect metal mobility during post-crystallization hydrothermal processes. The higher PGE tenors for the disseminated sulfides in the CGO dike relative to those in the FGO Intrusion are consistent with formation in a dynamic conduit where the early sulfide liquids left in the conduit by the FGO magma were subsequently upgraded by the subsequent surge of the CGO magma. The relatively low PGE tenors for the semi-massive and massive sulfides can be explained by lack of such an upgrading process for the sulfide due to their distal locations in a migrating conduit.

  19. Chalcophile element (Ni, Cu, PGE, and Au) variations in the Tamarack magmatic sulfide deposit in the Midcontinent Rift System: implications for dynamic ore-forming processes

    NASA Astrophysics Data System (ADS)

    Taranovic, Valentina; Ripley, Edward M.; Li, Chusi; Rossell, Dean

    2016-10-01

    correlation between Pt and Pd, and between individual IPGE. At a given Pt or Pd content, however, the semi-massive sulfide ores have higher IPGE contents than the disseminated sulfide samples. Modeling results show that the variations in PGE tenors (metals in recalculated 100 % sulfide) in the Tamarack magmatic sulfide deposit are mainly controlled by variable R factors (magma/sulfide-liquid mass ratios) during sulfide-liquid segregation and subsequent monosulfide solid solution (MSS) fractionation during cooling. The initial contents of Ir, Pt, and Pd in the parental magma, estimated from the metal tenors of the disseminated sulfides, are 0.2, 2, and 1.8 ppb, respectively, which are ˜1/5 of the values for the PGE-undepleted primitive basalts of the Midcontinent Rift System. The variations of PGE tenors in the semi-massive and massive sulfide ores can be explained by MSS fractional crystallization from sulfide liquids. Extreme variations in the PGE contents of the massive sulfides may also in part reflect metal mobility during post-crystallization hydrothermal processes. The higher PGE tenors for the disseminated sulfides in the CGO dike relative to those in the FGO Intrusion are consistent with formation in a dynamic conduit where the early sulfide liquids left in the conduit by the FGO magma were subsequently upgraded by the subsequent surge of the CGO magma. The relatively low PGE tenors for the semi-massive and massive sulfides can be explained by lack of such an upgrading process for the sulfide due to their distal locations in a migrating conduit.

  20. The Origin of Noble Gas Isotopic Heterogeneity in Icelandic Basalts

    NASA Technical Reports Server (NTRS)

    Dixon, E. T.; Honda, M.; McDougall, I.

    2001-01-01

    Two models for generation of heterogeneous He, Ne and Ar isotopic ratios in Icelandic basalts are evaluated using a mixing model and the observed noble gas elemental ratios in Icelandic basalts,Ocean island Basalt (OIBs) and Mid-Ocean Ridge Basalt (MORBs). Additional information is contained in the original extended abstract.

  1. Shock metamorphism of granulated lunar basalt

    NASA Technical Reports Server (NTRS)

    Schaal, R. B.; Thompson, T. D.; Hoerz, F.; Bauer, J. F.

    1979-01-01

    The paper deals with an extensive series of shock-recovery experiments performed on both nonporous crystalline basalt and its granulated and sieved counterpart to study the role of porosity and grain size in shock motomorphic effects under otherwise identical conditions. Shocked samples are compared with unshocked starting material in terms of textural and mineralogical modifications attributable to shock. A comparative petrographic and chemical characterization is presented of pulverized and sieved lunar basalt 75035 shocked between 6 and 75 GPa in comparison with holocrystalline disks of the same basalts shocked in 10 earlier experiments. Specifically, a petrographic classification of shock features is given, along with an estimation of relative amounts of shock glasses and a chemical characterization of shock glasses in each shocked granular basalt.

  2. Basalts Dredged from the Northeastern Pacific Ocean.

    PubMed

    Engel, C G; Engel, A E

    1963-06-21

    Volcanic rocks dredged from seamounts, fault ridges, and other major geological features of the northeast Pacific Ocean include a wide variety of basalts. Most of these are vesicular, porphyritic types with near analogues in the Hawaiian and other oceanic islands. In addition, aluminous basalts and diabasic theoleiites impoverished in potassium also occur. There is no simple correlation of composition, degree of oxidation, vesiculation, or hydration of these basalts with texture, or depth of dredge site. Most samples appear to have been extruded at much shallower depths than those now pertaining at the dredge site. The distribution of these basalts suggests that the andesite line coincides with or lies on the continent side of the foot of the continental slope.

  3. Naming Lunar Mare Basalts: Quo Vadimus Redux

    NASA Astrophysics Data System (ADS)

    Ryder, G.

    1999-01-01

    Nearly a decade ago, I noted that the nomenclature of lunar mare basalts was inconsistent, complicated, and arcane. I suggested that this reflected both the limitations of our understanding of the basalts, and the piecemeal progression made in lunar science by the nature of the Apollo missions. Although the word "classification" is commonly attached to various schemes of mare basalt nomenclature, there is still no classification of mare basalts that has any fundamental grounding. We remain basically at a classification of the first kind in the terms of Shand; that is, things have names. Quoting John Stuart Mill, Shand discussed classification of the second kind: "The ends of scientific classification are best answered when the objects are formed into groups respecting which a greater number of propositions can be made, and those propositions more important than could be made respecting any other groups into which the same things could be distributed." Here I repeat some of the main contents of my discussion from a decade ago, and add a further discussion based on events of the last decade. A necessary first step of sample studies that aims to understand lunar mare basalt processes is to associate samples with one another as members of the same igneous event, such as a single eruption lava flow, or differentiation event. This has been fairly successful, and discrete suites have been identified at all mare sites, members that are eruptively related to each other but not to members of other suites. These eruptive members have been given site-specific labels, e.g., Luna24 VLT, Apollo 11 hi-K, A12 olivine basalts, and Apollo 15 Green Glass C. This is classification of the first kind, but is not a useful classification of any other kind. At a minimum, a classification is inclusive (all objects have a place) and exclusive (all objects have only one place). The answer to "How should rocks be classified?" is far from trivial, for it demands a fundamental choice about nature

  4. Basalts Dredged from the Northeastern Pacific Ocean.

    PubMed

    Engel, C G; Engel, A E

    1963-06-21

    Volcanic rocks dredged from seamounts, fault ridges, and other major geological features of the northeast Pacific Ocean include a wide variety of basalts. Most of these are vesicular, porphyritic types with near analogues in the Hawaiian and other oceanic islands. In addition, aluminous basalts and diabasic theoleiites impoverished in potassium also occur. There is no simple correlation of composition, degree of oxidation, vesiculation, or hydration of these basalts with texture, or depth of dredge site. Most samples appear to have been extruded at much shallower depths than those now pertaining at the dredge site. The distribution of these basalts suggests that the andesite line coincides with or lies on the continent side of the foot of the continental slope. PMID:17802173

  5. Basalts dredged from the northeastern Pacific Ocean

    USGS Publications Warehouse

    Engel, C.G.; Engel, A.E.J.

    1963-01-01

    Volcanic rocks dredged from seamounts, fault ridges, and other major geological features of the northeast Pacific Ocean include a wide variety of basalts. Most of these are vesicular, porphyritic types with near analogues in the Hawaiian and other oceanic islands. in addition, aluminous basalts and diabasic tholeiites impoverished in potassium also occur. There is no simple correlation of composition, degree of oxidation, vesiculation, or hydration of these basalts with texture, or depth of dredge site. Most samples appear to have been extruded at much shallower depths than those now pertaining at the dredge site. the distribution of these basalts suggests that the andesite line coincides with or lies on the continent side of the foot of the continental slope.

  6. Basaltic Soil of Gale Crater: Crystalline Component Compared to Martian Basalts and Meteorites

    NASA Technical Reports Server (NTRS)

    Treiman, A. H.; Bish, D. L.; Ming, D. W.; Morris, R. V.; Schmidt, M.; Downs, R. T.; Stolper, E. M.; Blake, D. F.; Vaniman, D. T.; Achilles, C. N.; Chipera, S. J.; Bristow, T. F.; Crisp, J. A.; Farmer, J. A.; Morookian, J. M.; Morrison, S. M.; Rampe, E. B.; Sarrazin, P.; Yen, A. S.; Anderosn, R. C.; DesMarais, D. J.; Spanovich, N.

    2013-01-01

    A significant portion of the soil of the Rocknest dune is crystalline and is consistent with derivation from unweathered basalt. Minerals and their compositions are identified by X-ray diffraction (XRD) data from the CheMin instrument on MSL Curiosity. Basalt minerals in the soil include plagioclase, olivine, low- and high-calcium pyroxenes, magnetite, ilmenite, and quartz. The only minerals unlikely to have formed in an unaltered basalt are hematite and anhydrite. The mineral proportions and compositions of the Rocknest soil are nearly identical to those of the Adirondack-class basalts of Gusev Crater, Mars, inferred from their bulk composition as analyzed by the MER Spirit rover.

  7. Basaltic cannibalism at Thrihnukagigur volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Hudak, M. R.; Feineman, M. D.; La Femina, P. C.; Geirsson, H.

    2014-12-01

    Magmatic assimilation of felsic continental crust is a well-documented, relatively common phenomenon. The extent to which basaltic crust is assimilated by magmas, on the other hand, is not well known. Basaltic cannibalism, or the wholesale incorporation of basaltic crustal material into a basaltic magma, is thought to be uncommon because basalt requires more energy than higher silica rocks to melt. Basaltic materials that are unconsolidated, poorly crystalline, or palagonitized may be more easily ingested than fully crystallized massive basalt, thus allowing basaltic cannibalism to occur. Thrihnukagigur volcano, SW Iceland, offers a unique exposure of a buried cinder cone within its evacuated conduit, 100 m below the main vent. The unconsolidated tephra is cross-cut by a NNE-trending dike, which runs across the ceiling of this cave to a vent that produced lava and tephra during the ~4 Ka fissure eruption. Preliminary petrographic and laser ablation inductively coupled mass spectrometry (LA-ICP-MS) analyses indicate that there are two populations of plagioclase present in the system - Population One is stubby (aspect ratio < 1.7) with disequilibrium textures and low Ba/Sr ratios while Population Two is elongate (aspect ratio > 2.1), subhedral to euhedral, and has much higher Ba/Sr ratios. Population One crystals are observed in the cinder cone, dike, and surface lavas, whereas Population Two crystals are observed only in the dike and surface lavas. This suggests that a magma crystallizing a single elongate population of plagioclase intruded the cinder cone and rapidly assimilated the tephra, incorporating the stubbier population of phenocrysts. This conceptual model for basaltic cannibalism is supported by field observations of large-scale erosion upward into the tephra, which is coated by magma flow-back indicating that magma was involved in the thermal etching. While the unique exposure at Thrihnukagigur makes it an exceptional place to investigate basaltic

  8. Starch columns: Analog model for basalt columns

    NASA Astrophysics Data System (ADS)

    Müller, Gerhard

    1998-07-01

    Desiccation of starch-water mixtures produces tensile-crack patterns which appear to be interesting, but largely unknown study objects for fracture mechanics, structural geology, and volcanology. This paper concentrates on columnar jointing and on columns in starch. Starch columns have polygonal cross sections and are very similar to basalt columns. They are produced by lamp drying starch specimens with dimensions of several centimeters and have diameters in the millimeter range. The columns develop behind a crack front which propagates from the surface into the interior. The experiments, supported by X ray tomograms, show that polygonal regularity of the crack pattern is not present at the surface but develops during penetration. This transition is steered by a minimum-fracture-energy principle. The analogy between basalt cooling and starch desiccation is far reaching: water concentration in starch is analogous to temperature in basalt, both quantities obey diffusion equations, water loss is equivalent to heat loss, the resulting contraction stresses have similar dependences on depth and time, and in both cases the material strength is exceeded. The starch experiments show that column diameters are controlled by the depth gradient of water concentration at the crack front. High (low) gradients are connected with thin (thick) columns. By analogy, a similar relation with the temperature gradient exists for basalt columns. The (normalized) starch gradients are about 3 orders of magnitude larger than the (normalized) gradients in basalt. This explains why starch columns are much thinner than basalt columns. The gradients are so different, because the crack front speeds differ by a factor of about 10: after 3 days the speed is about 10 mm/d in starch but about 100 mm/d in basalt [Peck, 1978]. The speed difference, in turn, results from the difference of the diffusion constants: the hydraulic diffusivity of starch is 2 orders of magnitude lower than the thermal

  9. Wellbore cement fracture evolution at the cement–basalt caprock interface during geologic carbon sequestration

    SciTech Connect

    Jung, Hun Bok; Kabilan, Senthil; Carson, James P.; Kuprat, Andrew P.; Um, Wooyong; Martin, Paul F.; Dahl, Michael E.; Kafentzis, Tyler A.; Varga, Tamas; Stephens, Sean A.; Arey, Bruce W.; Carroll, KC; Bonneville, Alain; Fernandez, Carlos A.

    2014-08-07

    Composite Portland cement-basalt caprock cores with fractures, as well as neat Portland cement columns, were prepared to understand the geochemical and geomechanical effects on the integrity of wellbores with defects during geologic carbon sequestration. The samples were reacted with CO2-saturated groundwater at 50 ºC and 10 MPa for 3 months under static conditions, while one cement-basalt core was subjected to mechanical stress at 2.7 MPa before the CO2 reaction. Micro-XRD and SEM-EDS data collected along the cement-basalt interface after 3-month reaction with CO2-saturated groundwater indicate that carbonation of cement matrix was extensive with the precipitation of calcite, aragonite, and vaterite, whereas the alteration of basalt caprock was minor. X-ray microtomography (XMT) provided three-dimensional (3-D) visualization of the opening and interconnection of cement fractures due to mechanical stress. Computational fluid dynamics (CFD) modeling further revealed that this stress led to the increase in fluid flow and hence permeability. After the CO2-reaction, XMT images displayed that calcium carbonate precipitation occurred extensively within the fractures in the cement matrix, but only partially along the fracture located at the cement-basalt interface. The 3-D visualization and CFD modeling also showed that the precipitation of calcium carbonate within the cement fractures after the CO2-reaction resulted in the disconnection of cement fractures and permeability decrease. The permeability calculated based on CFD modeling was in agreement with the experimentally determined permeability. This study demonstrates that XMT imaging coupled with CFD modeling represent a powerful tool to visualize and quantify fracture evolution and permeability change in geologic materials and to predict their behavior during geologic carbon sequestration or hydraulic fracturing for shale gas production and enhanced geothermal systems.

  10. The mineralogy and the isotopic composition of sulfur in hydrothermal sulfide/sulfate deposits on the East Pacific Rise, 21 deg N latitude

    NASA Technical Reports Server (NTRS)

    Styrt, M. M.; Brackmann, A. J.; Holland, H. D.; Clark, B. C.; Pisutha-Arnond, V.; Eldridge, C. S.; Ohmoto, H.

    1981-01-01

    The mineralogy and isotopic composition of sulfur found in hydrothermal deposits associated with five groups of vents along the ridge axis of the East Pacific Rise near 21 deg N latitude are investigated. Solid samples of mixed sulfides and sulfates from mounds, chimneys and the surrounding sediment as well as fresh basaltic glass were examined with a portable X-ray fluorescence spectrometer and by scanning electron microscopy, X-ray diffractometry, and electron microprobe analysis. For the three vents of exit temperature close to 350 C, the chimneys are found to be rich in copper sulfides, while for those of temperatures around 300 C, zinc sulfide is found to predominate. The major sulfides found in the chimneys include wurtzite, chalcopyrite, pyrite and cubanite, with anhydrite the dominant sulfate. Significant mineralogical differences are found between active and inactive vents. The isotopic composition of sulfur in anhydrites from active vents is observed to be close to that of sea water and consistent with a derivation from sea water sulfate. The isotopic composition of sulfur in the sulfide minerals is explained in terms of precipitation from solutions with reduced sulfur derived from basalts or basaltic magmas, and sea water sulfate. Finally, the deposits are interpreted as the results of the mixing of H2S-dominated hydrothermal fluids with cold sea water near the sea floor.

  11. Hydrogen evolution from water through metal sulfide reactions

    NASA Astrophysics Data System (ADS)

    Saha, Arjun; Raghavachari, Krishnan

    2013-11-01

    Transition metal sulfides play an important catalytic role in many chemical reactions. In this work, we have conducted a careful computational study of the structures, electronic states, and reactivity of metal sulfide cluster anions M2SX- (M = Mo and W, X = 4-6) using density functional theory. Detailed structural analysis shows that these metal sulfide anions have ground state isomers with two bridging sulfide bonds, notably different in some cases from the corresponding oxides with the same stoichiometry. The chemical reactivity of these metal sulfide anions with water has also been carried out. After a thorough search on the reactive potential energy surface, we propose several competitive, energetically favorable, reaction pathways that lead to the evolution of hydrogen. Selectivity in the initial water addition and subsequent hydrogen migration are found to be the key steps in all the proposed reaction channels. Initial adsorption of water is most favored involving a terminal metal sulfur bond in Mo2S4- isomers whereas the most preferred orientation for water addition involves a bridging metal sulfur bond in the case of W2S4- and M2S5- isomers. In all the lowest energy H2 elimination steps, the interacting hydrogen atoms involve a metal hydride and a metal hydroxide (or thiol) group. We have also observed a higher energy reaction channel where the interacting hydrogen atoms in the H2 elimination step involve a thiol (-SH) and a hydroxyl (-OH) group. For all the reaction pathways, the Mo sulfide reactions involve a higher barrier than the corresponding W analogues. We observe for both metals that reactions of M2S4- and M2S5- clusters with water to liberate H2 are exothermic and involve modest free energy barriers. However, the reaction of water with M2S6- is highly endothermic with a considerable barrier due to saturation of the local bonding environment.

  12. Hydrogen evolution from water through metal sulfide reactions.

    PubMed

    Saha, Arjun; Raghavachari, Krishnan

    2013-11-28

    Transition metal sulfides play an important catalytic role in many chemical reactions. In this work, we have conducted a careful computational study of the structures, electronic states, and reactivity of metal sulfide cluster anions M2S(X)(-) (M = Mo and W, X = 4-6) using density functional theory. Detailed structural analysis shows that these metal sulfide anions have ground state isomers with two bridging sulfide bonds, notably different in some cases from the corresponding oxides with the same stoichiometry. The chemical reactivity of these metal sulfide anions with water has also been carried out. After a thorough search on the reactive potential energy surface, we propose several competitive, energetically favorable, reaction pathways that lead to the evolution of hydrogen. Selectivity in the initial water addition and subsequent hydrogen migration are found to be the key steps in all the proposed reaction channels. Initial adsorption of water is most favored involving a terminal metal sulfur bond in Mo2S4(-) isomers whereas the most preferred orientation for water addition involves a bridging metal sulfur bond in the case of W2S4(-) and M2S5(-) isomers. In all the lowest energy H2 elimination steps, the interacting hydrogen atoms involve a metal hydride and a metal hydroxide (or thiol) group. We have also observed a higher energy reaction channel where the interacting hydrogen atoms in the H2 elimination step involve a thiol (-SH) and a hydroxyl (-OH) group. For all the reaction pathways, the Mo sulfide reactions involve a higher barrier than the corresponding W analogues. We observe for both metals that reactions of M2S4(-) and M2S5(-) clusters with water to liberate H2 are exothermic and involve modest free energy barriers. However, the reaction of water with M2S6(-) is highly endothermic with a considerable barrier due to saturation of the local bonding environment.

  13. Volcanogenic Massive Sulfide Deposit Density

    USGS Publications Warehouse

    Mosier, Dan L.; Singer, Donald A.; Berger, Vladimir I.

    2007-01-01

    A mineral-deposit density model for volcanogenic massive sulfide deposits was constructed from 38 well-explored control areas from around the world. Control areas contain at least one exposed volcanogenic massive sulfide deposit. The control areas used in this study contain 150 kuroko, 14 Urals, and 25 Cyprus massive sulfide subtypes of volcanogenic massive sulfide deposits. For each control area, extent of permissive rock, number of exposed volcanogenic massive sulfide deposits, map scale, deposit age, and deposit density were determined. The frequency distribution of deposit densities in these 38 control areas provides probabilistic estimates of the number of deposits for tracts that are permissive for volcanogenic massive sulfide deposits-90 percent of the control areas have densities of 100 or more deposits per 100,000 square kilometers, 50 percent of the control areas have densities of 700 or more deposits per 100,000 square kilometers, and 10 percent of the control areas have densities of 3,700 or more deposits per 100,000 square kilometers. Both map scale and the size of the control area are shown to be predictors of deposit density. Probabilistic estimates of the number of volcanogenic massive sulfide deposits can be made by conditioning the estimates on sizes of permissive area. The model constructed for this study provides a powerful tool for estimating the number of undiscovered volcanogenic massive sulfide deposits when conducting resource assessments. The value of these deposit densities is due to the consistency of these models with the grade and tonnage and the descriptive models. Mineral-deposit density models combined with grade and tonnage models allow reasonable estimates of the number, size, and grades of volcanogenic massive sulfide deposits to be made.

  14. Saturation in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Roman, Ahmed; Hanna, James

    2015-03-01

    We consider a weakly nonlinear system consisting of a resonantly forced oscillator coupled to an unforced oscillator. It has long been known that, for quadratic nonlinearities and a 2:1 resonance between the oscillators, a perturbative solution of the dynamics exhibits a phenomenon known as saturation. At low forcing, the forced oscillator responds, while the unforced oscillator is quiescent. Above a critical value of the forcing, the forced oscillator's steady-state amplitude reaches a plateau, while that of the unforced oscillator increases without bound. We show that, contrary to established folklore, saturation is not unique to quadratically nonlinear systems. We present conditions on the form of the nonlinear couplings and resonance that lead to saturation. Our results elucidate a mechanism for localization or diversion of energy in systems of coupled oscillators, and suggest new approaches for the control or suppression of vibrations in engineered systems.

  15. Age and tectonic setting of the Bavanat Cu-Zn-Ag Besshi-type volcanogenic massive sulfide deposit, southern Iran

    NASA Astrophysics Data System (ADS)

    Mousivand, Fardin; Rastad, Ebrahim; Meffre, Sebastien; Peter, Jan M.; Mohajjel, Mohammad; Zaw, Khin; Emami, Mohammad Hashem

    2012-12-01

    The Bavanat Cu-Zn-Ag Besshi-type volcanogenic massive sulfide (VMS) deposit occurs within the Surian volcano-sedimentary complex in the Sanandaj-Sirjan zone (SSZ) of southern Iran. The Surian complex is comprised of pelite, sandstone, calcareous shale, basalt, gabbro sills, and thin-bedded limestone. Mineralization occurs as stratiform sheet-like and tabular orebodies hosted mainly by greenschist metamorphosed feldspathic and quartz feldspathic sandstone, basalt, and pelites. The basalts of the Surian complex show predominantly tholeiitic to transitional affinities, with a few samples that are alkalic in composition. Primitive mantle-normalized trace and rare earth element (REE) patterns of the Surian basalts display depletions in light REE, negative anomalies of Nb, Ta, and Ti, and positive anomalies of P. Positive P anomalies are indicative of minor crustal contamination. Furthermore, Th enrichments in the mid-ocean ridge basalt-normalized patterns of the Surian basalts are characteristic of rifted arc basalts emplaced in continental margin subduction zones. The high MgO content (>6 wt.%) of most Surian basalts and low TiO2 content of two samples (0.53 and 0.62 wt.%) are characteristic of boninites. The aforementioned features of the basalts indicate arc tholeiites emplaced in intra-arc rift environments and continental margin subduction zones. U-Pb dating by laser ablation- inductively coupled plasma mass spectrometry of detrital zircons extracted from the host feldspathic and quartz feldspathic sandstone yields various ages that are predominantly Permian and Triassic; however, the youngest zircons give a mean Early Jurassic concordant U-Pb age of 191 ± 12 Ma. This age, together with geological and petrochemical data, indicate that VMS mineralization formed in the Early Jurassic in pull-apart basins within the SSZ. These basins and the VMS mineralization may be temporally related to an intra-arc volcano-plutonic event associated with Neo-Tethyan oblique

  16. Studies of Magmatic Inclusions in the Basaltic Martian Meteorites Shergotty, Zagami, EETA 79001 and QUE 94201

    NASA Technical Reports Server (NTRS)

    Harvey, Ralph P.; McKay, Gordon A.

    1997-01-01

    inclusions; those found within early-forming pigeonite, intermediate and late-forming Ti, Fe-oxides and sulfides, and intermediate to late-forming phosphates. In this summer' s study we have made a detailed study of all of the various forms of inclusions found within the 4 basaltic martian meteorites listed above. Glasses and minerals within the inclusions were analyzed using the Camera SX-100 Electron Microprobe in Building 31. The mineralogy and textural context of the inclusions will then be used to explore the crystallization history of these specimens, and to investigate any differences in crystallization history or parental magma compositions between these rocks. In this manner, the magmatic inclusions provide a road map backwards toward the 'parental' compositions for the basaltic martian meteorites and provide significant insight into the igneous processes found within the crust of Mars.

  17. Effects of temperature, silicate melt composition, and oxygen fugacity on the partitioning of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide phases and silicate melt

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Audétat, Andreas

    2015-08-01

    application of this equation to natural samples of basaltic to rhyolitic composition yields DMSS/SM and DSL/SM values that agree with the measured values within ±0.5 log units for most of the elements, indicating the validity of the application of this equation to natural systems. Our partitioning data imply that sulfide liquid saturation in low-temperature intermediate to felsic melts causes a strong depletion in Cu, Au, Bi, and potentially Ag in the silicate melt, whereas MSS saturation may cause a depletion in Cu and potentially Au. Other elements including W, Zn, As, Mo, Sn, Sb, and Pb are much less or not affected by the saturation of sulfide liquid or MSS. These results place important constrains on the potential of magmas in forming porphyry-type ore deposits and the origin of the observed variability in metal ratios in porphyry-type ore deposits.

  18. Alteration of Rock Fragments from Columbia River Basalt Microcosms

    NASA Technical Reports Server (NTRS)

    Wentworth, Susan J.; Thomas-Keprta, Kathie L.; Velbel, Michael A.; McKay, David S.; Stevens, Todd O.

    1999-01-01

    During an earlier study, microorganisms were grown microcosms consisting of sterilized chips of Columbia River Basalt (CRB) and natural CRB ground water with its natural microflora; environmental conditions simulated a deep subsurface, anaerobic, dark environment. Subsequent scanning and transmission electron microscope (SEM and TEM) studies revealed the presence of several types of bacteria and biofilm, some of which were mineralized. Some of these biological features are very similar to possible biogenic features found in two meteorites from Mars, ALH84001 (found in Antarctica) and Nakhla (observed to fall in Egypt). Both ALH84001 and Nakhla contain traces of low-temperature aqueous alteration of silicates, oxides, and sulfides. The goals of this study are to use high-resolution field-emission SEM (FE-SEM) to examine the CRB samples for evidence of alteration features similar to those in the martian meteorites, to determine the extent of alteration during the CRB microcosm experiments, and to determine whether effects of biological activity can be distinguished from inorganic effects.

  19. A novel method for improving cerussite sulfidization

    NASA Astrophysics Data System (ADS)

    Feng, Qi-cheng; Wen, Shu-ming; Zhao, Wen-juan; Cao, Qin-bo; Lü, Chao

    2016-06-01

    Evaluation of flotation behavior, solution measurements, and surface analyses were performed to investigate the effects of chloride ion addition on the sulfidization of cerussite in this study. Micro-flotation tests indicate that the addition of chloride ions prior to sulfidization can significantly increase the flotation recovery of cerussite, which is attributed to the formation of more lead sulfide species on the mineral surface. Solution measurement results suggest that the addition of chloride ions prior to sulfidization induces the transformation of more sulfide ions from pulp solution onto the mineral surface by the formation of more lead sulfide species. X-ray diffraction and energy-dispersive spectroscopy indicate that more lead sulfide species form on the mineral surface when chloride ions are added prior to sulfidization. These results demonstrate that the addition of chloride ions prior to sulfidization can significantly improve the sulfidization of cerussite, thereby enhancing the flotation performance.

  20. Prevention of sulfide oxidation in sulfide-rich waste rock

    NASA Astrophysics Data System (ADS)

    Nyström, Elsa; Alakangas, Lena

    2015-04-01

    The ability to reduce sulfide oxidation in waste rock after mine closure is a widely researched area, but to reduce and/or inhibit the oxidation during operation is less common. Sulfide-rich (ca 30 % sulfur) waste rock, partially oxidized, was leached during unsaturated laboratory condition. Trace elements such as As and Sb were relatively high in the waste rock while other sulfide-associated elements such as Cu, Pb and Zn were low compared to common sulfide-rich waste rock. Leaching of unsaturated waste rock lowered the pH, from around six down to two, resulting in continuously increasing element concentrations during the leaching period of 272 days. The concentrations of As (65 mg/L), Cu (6.9 mg/L), Sb (1.2 mg/L), Zn (149 mg/L) and S (43 g/L) were strongly elevated at the end of the leaching period. Different alkaline industrial residues such as slag, lime kiln dust and cement kiln dust were added as solid or as liquid to the waste rock in an attempt to inhibit sulfide oxidation through neo-formed phases on sulfide surfaces in order to decrease the mobility of metals and metalloids over longer time scale. This will result in a lower cost and efforts of measures after mine closure. Results from the experiments will be presented.

  1. Nickel and Cobalt Partitioning Between Spinel and Basaltic Melt: Applications to Planetary Basalt Suites

    NASA Technical Reports Server (NTRS)

    Righter, K.

    2002-01-01

    New experimental spinel/melt partition coefficients for Ni and Co have been measured in basalt samples with natural levels of Ni and Co, are lower than previous high doping experiments, and are applied to several planetary basalt suites. Additional information is contained in the original extended abstract.

  2. Are flood basalt eruptions monogenetic or polygenetic?

    NASA Astrophysics Data System (ADS)

    Sheth, Hetu C.; Cañón-Tapia, Edgardo

    2015-11-01

    A fundamental classification of volcanoes divides them into "monogenetic" and "polygenetic." We discuss whether flood basalt fields, the largest volcanic provinces, are monogenetic or polygenetic. A polygenetic volcano, whether a shield volcano or a stratovolcano, erupts from the same dominant conduit for millions of years (excepting volumetrically small flank eruptions). A flood basalt province, built from different eruptive fissures dispersed over wide areas, can be considered a polygenetic volcano without any dominant vent. However, in the same characteristic, a flood basalt province resembles a monogenetic volcanic field, with only the difference that individual eruptions in the latter are much smaller. This leads to the question how a flood basalt province can be two very different phenomena at the same time. Individual flood basalt eruptions have previously been considered monogenetic, contrasted by only their high magma output (and lava fluidity) with typical "small-volume monogenetic" volcanoes. Field data from Hawaiian shield volcanoes, Iceland, and the Deccan Traps show that whereas many feeder dykes were single magma injections, and the eruptions can be considered "large monogenetic" eruptions, multiple dykes are equally abundant. They indicate that the same dyke fissure repeatedly transported separate magma batches, feeding an eruption which was thus polygenetic by even the restricted definition (the same magma conduit). This recognition helps in understanding the volcanological, stratigraphic, and geochemical complexity of flood basalts. The need for clear concepts and terminology is, however, strong. We give reasons for replacing "monogenetic volcanic fields" with "diffuse volcanic fields" and for dropping the term "polygenetic" and describing such volcanoes simply and specifically as "shield volcanoes," "stratovolcanoes," and "flood basalt fields."

  3. Partitioning of K, U, and Th between sulfide and silicate liquids - Implications for radioactive heating of planetary cores

    NASA Technical Reports Server (NTRS)

    Murrell, M. T.; Burnett, D. S.

    1986-01-01

    Experimental partitioning studies are reported of K, U, and Th between silicate and FeFeS liquids designed to test the proposal that actinide partitioning into sulfide liquids is more important then K partitioning in the radioactive heating of planetary cores. For a basaltic liquid at 1450 C and 1.5 GPa, U partitioning into FeFeS liquids is five times greater than K partitioning. A typical value for the liquid partition coefficient for U from a granitic silicate liquid at one atmosphere at 1150 C and low fO2 is about 0.02; the coefficient for Th is similar. At low fO2 and higher temperature, experiments with basaltic liquids produce strong Ca and U partitioning into the sulfide liquid with U coefficient greater than one. The Th coefficient is less strongly affected.

  4. Apparatus for use in sulfide chemiluminescence detection

    DOEpatents

    Spurlin, S.R.; Yeung, E.S.

    1987-01-06

    A method is described for chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

  5. Apparatus for use in sulfide chemiluminescence detection

    DOEpatents

    Spurlin, Stanford R.; Yeung, Edward S.

    1987-01-01

    A method of chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction.

  6. Experimental Partitioning of Chalcophile Elements between Mantle Silicate Minerals and Basaltic Melt at High Pressures and Temperatures - Implications for Sulfur Geochemistry of Mantle and Crust

    NASA Astrophysics Data System (ADS)

    Dasgupta, R.; Jego, S.; Ding, S.; Li, Y.; Lee, C. T.

    2015-12-01

    The behavior of chalcophile elements during mantle melting, melt extraction, and basalt differentiation is critical for formation of ore deposits and geochemical model and evolution of crust-mantle system. While chalcophile elements are strongly partitioned into sulfides, their behavior with different extent of melting, in particular, in the absence of sulfides, can only be modeled with complete knowledge of the partitioning behavior of these elements between dominant mantle minerals and basaltic melt with or without dissolved sulfide (S2-). However, experimental data on mineral-melt partitioning are lacking for many chalcophile elements. Crystallization experiments were conducted at 3 GPa and 1450-1600 °C using a piston cylinder and synthetic silicate melt compositions similar to low-degree partial melt of peridotite. Starting silicate mixes doped with 100-300 ppm of each of various chalcophile elements were loaded into Pt/graphite double capsules. To test the effect of dissolved sulfur in silicate melt on mineral-melt partitioning of chalcophile elements, experiments were conducted on both sulfur-free and sulfur-bearing (1100-1400 ppm S in melt) systems. Experimental phases were analyzed by EPMA (for major elements and S) and LA-ICP-MS (for trace elements). All experiments produced an assemblage of cpx + melt ± garnet ± olivine ± spinel and yielded new partition coefficients (D) for Sn, Zn, Mo, Sb, Bi, Pb, and Se for cpx/melt, olivine/melt, and garnet/melt pairs. Derived Ds (mineral/basalt) reveal little effect of S2- in the melt on mineral-melt partition coefficients of the measured chalcophile elements, with Ds for Zn, Mo, Bi, Pb decreasing by less than a factor of 2 from S-free to S-bearing melt systems or remaining similar, within error, between S-free and S-bearing melt systems. By combining our data with existing partitioning data between sulfide phases and silicate melt we model the fractionation of these elements during mantle melting and basalt

  7. Pump for Saturated Liquids

    NASA Technical Reports Server (NTRS)

    Elliott, D. G.

    1986-01-01

    Boiling liquids pumped by device based on proven components. Expanding saturated liquid in nozzle and diverting its phases along separate paths in liquid/vapor separator raises pressure of liquid. Liquid cooled in process. Pump makes it unnecessary to pressurize cryogenic liquids in order to pump them. Problems of introducing noncondensable pressurizing gas avoided.

  8. Platinum metals magmatic sulfide ores.

    PubMed

    Naldrett, A J; Duke, J M

    1980-06-27

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example.

  9. Lu-Hf constraints on the evolution of lunar basalts

    SciTech Connect

    Fujimaki, H.; Tatsumoto, M.

    1984-02-15

    Very low Ti basalts andd green glass samples from the moon show high Lu/Hf ratios and low Hf concentrations. Low-Ti lunar basalts show high and variable Lu/Hf ratios and higher Hf concentrations, whereas high-Ti lunar basalts show low Lu/Hf ratios and high Hf concentrations. KREEP basalts have constant Lu/Hf ratios and high but variable Hf concentrations. Using the Lu-Hf behavior as a constraint, we propose a model for the mare basalts evolution. This constraint requires extensive crystallization of the primary lunar magma ocean prior to formation of the lunar mare basalt sources and the KREEP basalts. Mare basalts are produced by the melting of the cumulate rocks, and KREEP basalts represent the residual liquid of the magma ocean.

  10. Evaluating crustal contamination in continental basalts: the isotopic composition of the Picture Gorge Basalt of the Columbia River Basalt Group

    NASA Astrophysics Data System (ADS)

    Brandon, Alan D.; Hooper, Peter R.; Goles, Gordon G.; Lambert, Richard St J.

    1993-09-01

    Crustal contamination of basalts located in the western United States has been generally under-emphasized, and much of their isotopic variation has been ascribed to multiple and heterogeneous mantle sources. Basalts of the Miocene Columbia River Basalt Group in the Pacific Northwest have passed through crust ranging from Precambrian to Tertiary in age. These flows are voluminous, homogenous, and underwent rapid effusion, all of which are disadvantages for crustal contamination while en route to the surface. The Picture Gorge Basalt of the Columbia River Basalt Group erupted through Paleozoic and Mesozoic oceanic accreted terranes in central Oregon, and earlier studies on these basalts provided no isotopic evidence for crustal contamination. New Sr, Nd, Pb, and O isotopic data presented here indicate that the isotopic variation of the Picture Gorge Basalt is very small, 87Sr/86Sr=0.70307 0.70371, ɛNd=+7.7-+4.8, δ18O=+5.6±6.1, and 206Pb/204Pb=18.80 18.91. Evaluation of the Picture Gorge compositional variation supports a model where two isotopic components contributed to Picture Gorge Basalt genesis. The first component (C1) is reflected by low 87Sr/86Sr, high ɛNd, and nonradiogenic Pb isotopic compositions. Basalts with C1 isotopic compositions have large MgO, Ni, and Cr contents and mantle-like δ18O=+5.6. C1 basalts have enrichments in Ba coupled with depletions in Nb and Ta. These characteristics are best explained by derivation from a depleted mantle source which has undergone a recent enrichment by fluids coming from a subducted slab. This C1 mantle component is prevalent throughout the Pacific Northwest. The second isotopic component has higher 87Sr/ 86Sr and δ18O, lower ɛNd, and more radiogenic Pb isotopic compositions than C1. There is a correlation in the Picture Gorge data of Sr, Nd, and Pb isotopes with differentiation indicators such as decreasing Mg#, and increasing K2O/TiO2, Ba, Ba/Zr, Rb/Sr, La/Sm, and La/Yb. Phase equilibrium and mineralogical

  11. Geochemical diversity of shergottite basalts: Mixing and fractionation, and their relation to Mars surface basalts

    NASA Astrophysics Data System (ADS)

    Treiman, Allan H.; Filiberto, Justin

    2015-04-01

    The chemical compositions of shergottite meteorites, basaltic rocks from Mars, provide a broad view of the origins and differentiation of these Martian magmas. The shergottite basalts are subdivided based on their Al contents: high-Al basalts (Al > 5% wt) are distinct from low-Al basalts and olivine-phyric basalts (both with Al < 4.5% wt). Abundance ratios of highly incompatible elements (e.g., Th, La) are comparable in all the shergottites. Abundances of less incompatible elements (e.g., Ti, Lu, Hf) in olivine-phyric and low-Al basalts correlate well with each other, but the element abundance ratios are not constant; this suggests mixing between components, both depleted and enriched. High-Al shergottites deviate from these trends consistent with silicate mineral fractionation. The "depleted" component is similar to the Yamato-980459 magma; approximately, 67% crystal fractionation of this magma would yield a melt with trace element abundances like QUE 94201. The "enriched" component is like the parent magma for NWA 1068; approximately, 30% crystal fractionation from it would yield a melt with trace element abundances like the Los Angeles shergottite. This component mixing is consistent with radiogenic isotope and oxygen fugacity data. These mixing relations are consistent with the compositions of many of the Gusev crater basalts analyzed on Mars by the Spirit rover (although with only a few elements to compare). Other Mars basalts fall off the mixing relations (e.g., Wishstone at Gusev, Gale crater rocks). Their compositions imply that basalt source areas in Mars include significant complexities that are not present in the source areas for the shergottite basalts.

  12. Sulfide-mediated dehydrative glycosylation.

    PubMed

    Nguyen, H M; Chen, Y; Duron, S G; Gin, D Y

    2001-09-12

    The development of a new method for glycosylation with 1-hydroxy glycosyl donors employing dialkyl sulfonium reagents is described. The process employs the reagent combination of a dialkyl sulfide and triflic anhydride to effect anomeric bond constructions. This controlled dehydrative coupling of various C(1)-hemiacetal glycosyl donors and nucleophilic acceptors proceeds by way of a sulfide-to-sulfoxide oxidation process in which triflic anhydride serves as the oxidant.

  13. Chemical Bonding in Sulfide Minerals

    SciTech Connect

    Vaughan, David J.; Rosso, Kevin M.

    2006-08-01

    An understanding of chemical bonding and electronic structure in sulfide minerals is central to any attempt at understanding their crystal structures, stabilities and physical properties. It is also an essential precursor to understanding reactivity through modeling surface structure at the molecular scale. In recent decades, there have been remarkable advances in first principles (ab initio) methods for the quantitative calculation of electronic structure. These advances have been made possible by the very rapid development of high performance computers. Several review volumes that chart the applications of these developments in mineralogy and geochemistry are available (Tossell and Vaughan, 1992; Cygan and Kubicki, 2001). An important feature of the sulfide minerals is the diversity of their electronic structures, as evidenced by their electrical and magnetic properties (see Pearce et al. 2006, this volume). Thus, sulfide minerals range from insulators through semiconductors to metals, and exhibit every type of magnetic behavior. This has presented problems for those attempting to develop bonding models for sulfides, and also led to certain misconceptions regarding the kinds of models that may be appropriate. In this chapter, chemical bonding and electronic structure models for sulfides are reviewed with emphasis on more recent developments. Although the fully ab initio quantitative methods are now capable of a remarkable degree of sophistication in terms of agreement with experiment and potential to interpret and predict behavior with varying conditions, both qualitative and more simplistic quantitative approaches will also be briefly discussed. This is because we believe that the insights which they provide are still helpful to those studying sulfide minerals. In addition to the application of electronic structure models and calculations to solid sulfides, work on sulfide mineral surfaces (Rosso and Vaughan 2006a,b) and solution complexes and clusters (Rickard

  14. The Eagle and East Eagle sulfide ore-bearing mafic-ultramafic intrusions in the Midcontinent Rift System, upper Michigan: Geochronology and petrologic evolution

    NASA Astrophysics Data System (ADS)

    Ding, Xin; Li, Chusi; Ripley, Edward M.; Rossell, Dean; Kamo, Sandra

    2010-03-01

    The Eagle and East Eagle intrusions are small, subvertical dike-like mafic-ultramafic bodies that cut Proterozoic sedimentary strata in the Baraga Basin in northern Michigan. The Eagle intrusion hosts a newly discovered magmatic Ni-Cu-PGE deposit. The nearby East Eagle intrusion also contains sulfide mineralization, but the extent of this mineralization has yet to be determined by further drilling. Both intrusions contain olivine-bearing rocks such as feldspathic peridotite, melatroctolite, and olivine melagabbro. Sulfide accumulations range from disseminated at both Eagle and East Eagle to semimassive and massive at Eagle. U-Pb baddeleyite dating gives a crystallization age of 1107.2 ± 5.7 Ma for the Eagle intrusion, coeval with eruption of picritic basalts at the base of the volcanic succession in the Midcontinent Rift System (MRS). The Fo contents of olivine cores in the Eagle and East Eagle intrusions vary between 75 and 85 mol %, higher than those of olivine in larger layered intrusions in the MRS such as the Duluth Complex. The FeO/MgO ratios and Al2O3 contents of the parental magmas for the Eagle and East Eagle intrusions inferred from olivine and spinel compositions are similar to those of picritic basalts in the base of the MRS volcanic succession. These petrochemical data suggest that the Eagle and East Eagle intrusions are the intrusive equivalents of high-MgO basalts that erupted in the early stages of continental magmatism associated with the development of the rift. Variations in mineral compositions and incompatible trace element ratios suggest that at least three major pulses of magmas were involved in the formation of low-sulfide rocks in the Eagle intrusion. Lower Fo contents of olivine associated with semimassive sulfides as compared to that of olivine in low-sulfide rocks suggest that the magma associated with the semimassive sulfide was more fractionated than the parental magmas of the low-sulfide rocks in the Eagle intrusion. Accumulation of

  15. Oxygen consumption in subseafloor basaltic crust

    NASA Astrophysics Data System (ADS)

    Orcutt, B. N.; Wheat, C. G.; Hulme, S.; Edwards, K. J.; Bach, W.

    2012-12-01

    Oceanic crust is the largest potential habitat for life on Earth and may contain a significant fraction of Earth's total microbial biomass, yet little is known about the form and function of life in this vast subseafloor realm that covers nearly two-thirds of the Earth's surface. A deep biosphere hosted in subseafloor basalts has been suggested from several lines of evidence; yet, empirical analysis of metabolic reaction rates in basaltic crust is lacking. Here we report the first measure of oxygen consumption in young (~ 8 Ma) and cool (<25 degrees C) basaltic crust, calculated from modeling oxygen and strontium profiles in basal sediments collected during Integrated Ocean Drilling Program (IODP) Expedition 336 to 'North Pond', a sediment 'pond' on the western flank of the Mid-Atlantic Ridge (MAR), where vigorous fluid circulation within basaltic crust occurs. Dissolved oxygen concentrations increased towards the sediment-basement interface, indicating an upward diffusional supply from oxic fluids circulating within the crust. A parametric reaction-transport model suggests oxygen consumption rates on the order of 0.5-500 nmol per cubic centimeter fluid per day in young and cool basaltic crust, providing sufficient energy to support a subsurface crustal biosphere.

  16. Finding Basalt Chips from Distant Maria

    NASA Astrophysics Data System (ADS)

    Taylor, G. J.

    2006-04-01

    The Apollo 16 landing site is in the lunar highlands, over 200 kilometers away from the nearest maria. Nevertheless, the Apollo 16 regolith contains a small percentage (<1%) of tiny fragments thrown to the site from distant maria. Ryan Zeigler, his colleagues at Washington University in St. Louis: Randy Korotev, Brad Jolliff, and the late Larry Haskin, and Jeffrey Gillis-Davis (University of Hawaii) made a detailed study of the chemical composition and mineralogy of fragments (only 2-4 millimeters across) of mare basalts. The basalts vary in composition, but are similar to other types identified previously. The team matched the compositions of the fragments to compositions of mare surfaces in the Apollo 16 region using remote sensing data from the Clementine mission. This blending of cosmochemical and remote sensing analyses allowed them to make educated guesses about where each of the basalt fragments may have originated. We now have a fuller understanding of the range of compositions of mare basalts and, because basalts record a wealth of information about planetary interiors, this research enlightens us about the diversity of rock compositions in the lunar mantle.

  17. Can we identify source lithology of basalt?

    PubMed

    Yang, Zong-Feng; Zhou, Jun-Hong

    2013-01-01

    The nature of source rocks of basaltic magmas plays a fundamental role in understanding the composition, structure and evolution of the solid earth. However, identification of source lithology of basalts remains uncertainty. Using a parameterization of multi-decadal melting experiments on a variety of peridotite and pyroxenite, we show here that a parameter called FC3MS value (FeO/CaO-3*MgO/SiO2, all in wt%) can identify most pyroxenite-derived basalts. The continental oceanic island basalt-like volcanic rocks (MgO>7.5%) (C-OIB) in eastern China and Mongolia are too high in the FC3MS value to be derived from peridotite source. The majority of the C-OIB in phase diagrams are equilibrium with garnet and clinopyroxene, indicating that garnet pyroxenite is the dominant source lithology. Our results demonstrate that many reputed evolved low magnesian C-OIBs in fact represent primary pyroxenite melts, suggesting that many previous geological and petrological interpretations of basalts based on the single peridotite model need to be reconsidered.

  18. Can we identify source lithology of basalt?

    PubMed Central

    Yang, Zong-Feng; Zhou, Jun-Hong

    2013-01-01

    The nature of source rocks of basaltic magmas plays a fundamental role in understanding the composition, structure and evolution of the solid earth. However, identification of source lithology of basalts remains uncertainty. Using a parameterization of multi-decadal melting experiments on a variety of peridotite and pyroxenite, we show here that a parameter called FC3MS value (FeO/CaO-3*MgO/SiO2, all in wt%) can identify most pyroxenite-derived basalts. The continental oceanic island basalt-like volcanic rocks (MgO>7.5%) (C-OIB) in eastern China and Mongolia are too high in the FC3MS value to be derived from peridotite source. The majority of the C-OIB in phase diagrams are equilibrium with garnet and clinopyroxene, indicating that garnet pyroxenite is the dominant source lithology. Our results demonstrate that many reputed evolved low magnesian C-OIBs in fact represent primary pyroxenite melts, suggesting that many previous geological and petrological interpretations of basalts based on the single peridotite model need to be reconsidered. PMID:23676779

  19. Micromechanics of brittle faulting and cataclastic flow in Mount Etna basalt

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Baud, Patrick; Vinciguerra, Sergio; Wong, Teng-fong

    2016-06-01

    Understanding how the strength of volcanic rocks varies with stress state, pressure, and microstructural attributes is fundamental to understanding the dynamics and tectonics of a volcanic system and also very important in applications such as geothermics or reservoir management in volcanic environments. In this study we investigated the micromechanics of deformation and failure in basalt, focusing on samples from Mount Etna. We performed 65 uniaxial and triaxial compression experiments on nominally dry and water-saturated samples covering a porosity range between 5 and 16%, at effective pressures up to 200 MPa. Dilatancy and brittle faulting were observed in all samples with porosity of 5%. Water-saturated samples were found to be significantly weaker than comparable dry samples. Shear-enhanced compaction was observed at effective pressures as low as 80 MPa in samples of 8% porosity. Microstructural data revealed the complex interplay of microcracks, pores, and phenocrysts on dilatant failure and inelastic compaction in basalt. The micromechanics of brittle failure is controlled by wing crack propagation under triaxial compression and by pore-emanated cracking under uniaxial compression especially in the more porous samples. The mechanism of inelastic compaction in basalt is cataclastic pore-collapse in agreement with a recent dual-porosity model.

  20. Hydrogen Sulfide Oxidation by Myoglobin.

    PubMed

    Bostelaar, Trever; Vitvitsky, Victor; Kumutima, Jacques; Lewis, Brianne E; Yadav, Pramod K; Brunold, Thomas C; Filipovic, Milos; Lehnert, Nicolai; Stemmler, Timothy L; Banerjee, Ruma

    2016-07-13

    Enzymes in the sulfur network generate the signaling molecule, hydrogen sulfide (H2S), from the amino acids cysteine and homocysteine. Since it is toxic at elevated concentrations, cells are equipped to clear H2S. A canonical sulfide oxidation pathway operates in mitochondria, converting H2S to thiosulfate and sulfate. We have recently discovered the ability of ferric hemoglobin to oxidize sulfide to thiosulfate and iron-bound hydropolysulfides. In this study, we report that myoglobin exhibits a similar capacity for sulfide oxidation. We have trapped and characterized iron-bound sulfur intermediates using cryo-mass spectrometry and X-ray absorption spectroscopy. Further support for the postulated intermediates in the chemically challenging conversion of H2S to thiosulfate and iron-bound catenated sulfur products is provided by EPR and resonance Raman spectroscopy in addition to density functional theory computational results. We speculate that the unusual sensitivity of skeletal muscle cytochrome c oxidase to sulfide poisoning in ethylmalonic encephalopathy, resulting from the deficiency in a mitochondrial sulfide oxidation enzyme, might be due to the concentration of H2S by myoglobin in this tissue. PMID:27310035

  1. Lithoautotrophic microbial ecosystems in deep basalt aquifers

    SciTech Connect

    Stevens, T.O.; McKinley, J.P.

    1995-10-20

    Bacterial communities were detected in deep crystalline rock aquifers within the Columbia River Basalt Group (CRB). CRB ground waters contained up to 60 {mu}M dissolved H{sub 2} and autotrophic microorganisms outnumbered heterotrophs. Stable carbon isotope measurements implied that autotrophic methanogenesis dominated this ecosystem and was coupled to the depletion of dissolved inorganic carbon. In laboratory experiments, H{sub 2} a potential energy source for bacteria, was produced by reactions between crushed basalt and anaerobic water. Microcosms containing only crushed basalt and ground water supported microbial growth. These results suggest that the CRB contains a lithoautotrophic microbial ecosystem that is independent of photosynthetic primary production. 38 refs., 4 figs., 3 tabs.

  2. Carbon Solubility of Molten Sulfides at 2-3 GPa

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Hirschmann, M. M.

    2012-12-01

    Sulfide is molten through much of Earth's upper mantle and so could have an important influence on geochemical and geophysical properties. For example, liquid sulfide could dissolve appreciable carbon, and thereby be a significant sink for reduced carbon in the mantle and perhaps be associated with carbon transport, including diamond precipitation. Here we present experimental data on the phase relations and carbon solubility of sulfides at 2-3 GPa in graphite capsules. Carbon was analyzed by EMPA using an LDE2 crystal and a 10 kV, 80 nA beam, and secondary steel and carbide standards. Repeated analyses of 99.995 wt% Fe indicate a C blank of 0.47 ± 0.12 wt.% (n=38), which was subtracted from the analyses. The limit of detection is therefore likely near 0.1-0.15 wt.%, but we take a more conservative value of 0.27 wt.%, which is the concentration in NIST C1248 steel, the lowest standard for which we unambiguously measure C. FeS monosulfide melts coexist with crystalline sulfide at 2GPa and 1100°C, and at 3GPa and 1200°C, respectively. Lower temperatures are subsolidus and higher temperatures produce only liquids (+graphite). For Fe-S liquids at 2GPa,1500-1600°C and 3GPa, 1600°C, at low bulk S content (5-10 wt.%), a carbide melt coexists with the sulfide. More sulfur-rich bulk compositions produce two immiscible liquids which are approximately (Fe~93%S2~3%C2~4%) and (Fe~70%S~30%)., but Ni addition diminishes the miscibility gap. Carbon solubility in (Fe0.5,Ni0.5)-S liquids diminishes with decreasing metal/sulfide ratio; up to 10 wt.% S, solubility is 2 wt.% C, but diminishes to <1 wt.% at 15 wt% S and is below detection at >20 wt.% S. At 2GPa and 1600°C, other graphite-saturated monosulfide compositions, (Fe1-x,Nix)S (x=0.33,0.50,0.67), FeCuS2 NiS, CuS, and CoS, dissolve less C than detection limit. We detect <0.5 wt.% C in Ni metal and Cu metal in graphite-saturated compositions. In the shallow mantle, where sulfide liquid approximates monosulfide stoichiometry

  3. Basaltic Volcanism and Ancient Planetary Crusts

    NASA Technical Reports Server (NTRS)

    Shervais, John W.

    1993-01-01

    The purpose of this project is to decipher the origin of rocks which form the ancient lunar crust. Our goal is to better understand how the moon evolved chemically and, more generally, the processes involved in the chemical fractionation of terrestrial planetoids. This research has implications for other planetary bodies besides the Moon, especially smaller planetoids which evolved early in the history of the solar system and are now thermally stable. The three main areas focused on in our work (lunar mare basalts, KREEP basalts, and plutonic rocks of the lunar highlands) provide complementary information on the lunar interior and the processes that formed it.

  4. Capillary saturation and desaturation.

    PubMed

    Hilfer, R; Armstrong, R T; Berg, S; Georgiadis, A; Ott, H

    2015-12-01

    Capillary desaturation experiments produce disconnected (trapped) ganglia of mesoscopic sizes intermediate between pore size and system size. Experimental evidence for interactions between these mesoscale clusters during desaturation is analyzed and discussed within the established microscopic and macroscopic laws of Newton, Young-Laplace, and Darcy. A theoretical expression for capillary number correlations is introduced that seems to have remained unnoticed. It expresses capillary desaturation curves in terms of stationary capillary pressures and relative permeabilities. The theoretical expression shows that the plateau saturation in capillary desaturation curves may in general differ from the residual nonwetting saturation defined through the saturation limit of the main hysteresis loop. Hysteresis effects as well as the difference between wetting and nonwetting fluids are introduced into the analysis of capillary desaturation experiments. The article examines experiments with different desaturation protocols and discusses the existence of a mesoscopic length scale intermediate between pore scale and sample scale. The theoretical expression is derived entirely within the existing traditional theory of two-phase flow in porous media and compared to a recent experiment. PMID:26764820

  5. Cumulate xenoliths from St. Vincent, Lesser Antilles Island Arc: a window into upper crustal differentiation of mantle-derived basalts

    NASA Astrophysics Data System (ADS)

    Tollan, P. M. E.; Bindeman, I.; Blundy, J. D.

    2012-02-01

    In order to shed light on upper crustal differentiation of mantle-derived basaltic magmas in a subduction zone setting, we have determined the mineral chemistry and oxygen and hydrogen isotope composition of individual cumulus minerals in plutonic blocks from St. Vincent, Lesser Antilles. Plutonic rock types display great variation in mineralogy, from olivine-gabbros to troctolites and hornblendites, with a corresponding variety of cumulate textures. Mineral compositions differ from those in erupted basaltic lavas from St. Vincent and in published high-pressure (4-10 kb) experimental run products of a St. Vincent high-Mg basalt in having higher An plagioclase coexisting with lower Fo olivine. The oxygen isotope compositions (δ18O) of cumulus olivine (4.89-5.18‰), plagioclase (5.84-6.28‰), clinopyroxene (5.17-5.47‰) and hornblende (5.48-5.61‰) and hydrogen isotope composition of hornblende (δD = -35.5 to -49.9‰) are all consistent with closed system magmatic differentiation of a mantle-derived basaltic melt. We employed a number of modelling exercises to constrain the origin of the chemical and isotopic compositions reported. δ18OOlivine is up to 0.2‰ higher than modelled values for closed system fractional crystallisation of a primary melt. We attribute this to isotopic disequilibria between cumulus minerals crystallising at different temperatures, with equilibration retarded by slow oxygen diffusion in olivine during prolonged crustal storage. We used melt inclusion and plagioclase compositions to determine parental magmatic water contents (water saturated, 4.6 ± 0.5 wt% H2O) and crystallisation pressures (173 ± 50 MPa). Applying these values to previously reported basaltic and basaltic andesite lava compositions, we can reproduce the cumulus plagioclase and olivine compositions and their associated trend. We conclude that differentiation of primitive hydrous basalts on St. Vincent involves crystallisation of olivine and Cr-rich spinel at depth

  6. Petrogenesis of the flood-basalt sequence at Noril'sk, North Central Siberia

    USGS Publications Warehouse

    Fedorenko, V.A.; Lightfoot, P.C.; Naldrett, A.J.; Czamanske, G.K.; Hawkesworth, C.J.; Wooden, J.L.; Ebel, D.S.

    1996-01-01

    The 3500-m-thick sequence of volcanic rocks at Noril'sk, formed during a brief interval (???1 m.y.) at the Permian/Triassic time boundary (???251 Ma), represents the earliest part of the ???6500-m-thick sequence presently ascribed to the Siberian flood-basalt province. It is composed of picritic and basaltic lavas of both low-Ti and high-Ti parentage. Extensive geological, geochemical, and isotopic study of the lava sequence and related intrusions allows detailed reconstruction of its petrogenesis. Various crustal-related processes - fractionation, crustal contamination, sulfide separation, and magma mixing - participated in the formation of the lavas. The geochemical and isotopic characteristics indicative of these processes, as well as mantle-related signatures of lava compositions, are discussed. Based on these characteristics, detailed interpretations of lava genesis and evolution throughout the Noril'sk sequence are presented. Eight varieties of lavas are recognized to be primitive, similar in composition to primary mantle melts; they varied from low-Mg basalts to olivine tholeiites or picrites, with normal tholeiites predominating. The primitive lavas are subdivided into four groups (magma types) on the basis of trace-element ratios (principally. Gd/Yb, Th/U, La/Yb, Ta/La, Ti/Sc, and V/Yb) and isotopic data. Three of the groups include both basaltic and picritic primitive lavas (with low-Mg basalts present in one of them), whereas the fourth group is represented exclusively by tholeiites. Distinctions among the groups cannot be related to degree of melting, and isotopic data indicate that none of the magma types could have formed by mixing or contamination of other types. Apparently, only differences in source composition and/or depth of melting can explain the magmatic diversity. This multitude of primitive magma types may be explained by melting in different layers of the upper mantle, which is complexly layered beneath Siberia to depths of 270 km. Moreover

  7. Crustal contamination and sulfide immiscibility history of the Permian Huangshannan magmatic Ni-Cu sulfide deposit, East Tianshan, NW China

    NASA Astrophysics Data System (ADS)

    Mao, Ya-Jing; Qin, Ke-Zhang; Tang, Dong-Mei; Feng, Hong-Ye; Xue, Sheng-Chao

    2016-11-01

    The Huangshannan mafic-ultramafic intrusion is a Permian Ni-Cu sulfide-bearing intrusion in the southern margin of the Central Asian Orogenic Belt. The intrusion consists of an ultramafic unit, which is composed of lherzolite and olivine websterite, and a mafic unit, which is composed of olivine gabbronorite, gabbronorite and leuco-gabbronorite. This intrusion was formed by two separate pulses of magma: a more primitive magma for the early ultramafic unit and a more evolved magma for the late mafic unit. U-Pb isotope geochronology of zircon from the mafic unit yields an age of 278 ± 2 Ma. According to its olivine and Cr-rich spinel compositions, the estimated parental magma of lherzolite for the Huangshannan intrusion has 12.4 wt.% MgO, indicating picritic affinity. Fractional crystallization modeling results and the presence of rounded sulfide inclusions in an olivine crystal (Fo 86.7) indicate that sulfide immiscibility was achieved at the beginning of olivine fractionation. Co-magmatic zircon crystals from gabbronorite have a δ18O value close to 6.5‰, which is 1.2‰ higher than the typical mantle value and suggests significant crustal contamination (∼20%). The positive εHf(t) values of co-magmatic zircon (which vary from +9.2 to +15.3) and positive whole rock εNd(t) values (which vary from +4.7 to +7.8) also indicate that the parental magma was derived from a depleted mantle source and contaminated by 5-20% juvenile arc crust and then by ∼5% upper crustal materials. However, modeling results of sulfur content at sulfide saturation reveal that such a large amount of crustal contamination is not sufficient to trigger sulfide saturation in the parental magma, which strongly suggests that external sulfur addition, probably during contamination, has played a critical role in causing sulfide immiscibility. Furthermore, the arc magmatism geochemical signatures of the Huangshannan intrusion, such as significant Nb and Ta depletion relative to La and low Ca

  8. Conceptual model of the geometry and physics of water flow in a fractured basalt vadose zone

    NASA Astrophysics Data System (ADS)

    Faybishenko, Boris; Doughty, Christine; Steiger, Michael; Long, Jane C. S.; Wood, Thomas R.; Jacobsen, Janet S.; Lore, Jason; Zawislanski, Peter T.

    2000-12-01

    A conceptual model of the geometry and physics of water flow in a fractured basalt vadose zone was developed based on the results of lithological studies and a series of ponded infiltration tests conducted at the Box Canyon site near the Idaho National Engineering and Environmental Laboratory. The infiltration tests included one 2-week test in 1996, three 2-day tests in 1997, and one 4-day test in 1997. For the various tests, initial infiltration rates ranged from 4.1 cm/d (4.75 ×10-7 m/s) to 17.7 cm/d (2.05×10-7 m/s) and then decreased with time, presumably because of mechanical or microbiological clogging of fractures and esicular basalt in the near-surface zone, as well as the effect of entrapped air. The subsurface moisture redistribution was monitored with tensiometers, neutron logging, time domain reflectrometry, and ground-penetrating radar. A conservative tracer, potassium bromide, was added to the pond water at a concentration of 3 g/L to monitor water flow with electrical resistivity probes and water sampling. Analysis of the data shows evidence of preferential flow rather than the propagation of a uniform wetting front. We propose a conceptual model describing the saturation-desaturation behavior of the basalt, in which rapid preferential flow occurs through the largest vertical fractures, followed by a gradual wetting of other fractures and the basalt matrix. Fractures that are saturated early in the tests may become desaturated thereafter, which we attribute to the redistribution of water between fractures and matrix. Lateral movement of water takes place within horizontal fracture and rubble zones, enabling development of perched water bodies.

  9. Pore water chemistry reveals gradients in mineral transformation across a model basaltic hillslope

    NASA Astrophysics Data System (ADS)

    Pohlmann, Michael; Dontsova, Katerina; Root, Robert; Ruiz, Joaquin; Troch, Peter; Chorover, Jon

    2016-06-01

    The extent of weathering incongruency during soil formation from rock controls local carbon and nutrient cycling in ecosystems, as well as the evolution of hydrologic flow paths. Prior studies of basalt weathering, including those that have quantified the dynamics of well-mixed, bench-scale laboratory reactors or characterized the structure and integrated response of field systems, indicate a strong influence of system scale on weathering rate and trajectory. For example, integrated catchment response tends to produce lower weathering rates than do well mixed reactors, but the mechanisms underlying these disparities remain unclear. Here we present pore water geochemistry and physical sensor data gathered during two controlled rainfall-runoff events on a large-scale convergent model hillslope mantled with 1 m uniform depth of granular basaltic porous media. The dense sampler and sensor array (1488 samplers and sensors embedded in 330 m3 of basalt) showed that rainfall-induced dissolution of basaltic glass produced supersaturation of pore waters with respect to multiple secondary solids including allophane, gibbsite, ferrihydrite, birnessite and calcite. The spatial distribution of saturation state was heterogeneous, suggesting an accumulation of solutes leading to precipitation of secondary solids along hydrologic flow paths. Rapid dissolution of primary silicates was widespread throughout the entire hillslope, irrespective of up-gradient flowpath length. However, coherent spatial variations in solution chemistry and saturation indices were observed in depth profiles and between distinct topographic regions of the hillslope. Colloids (110-2000 nm) enriched in iron (Fe), aluminum (Al), and phosphorus (P) were mobile in soil pore waters.

  10. Reactivity of Sulfide Mineral Surfaces

    SciTech Connect

    Rosso, Kevin M.; Vaughan, David J.

    2006-08-01

    In the preceding chapter, the fundamental nature of sulfide mineral surfaces has been discussed, and the understanding we have of the ways in which the surface differs from a simple truncation of the bulk crystal structure reviewed. This naturally leads on to considering our understanding of sulfide surface chemistry, in the sense of how sulfide surfaces interact and react, particularly with gases and liquids. As noted elsewhere in this volume, research on sulfide mineral surfaces and surface reactivity is a relatively recent concern of mineralogists and geochemists, partly prompted by the availability of new imaging and spectroscopic methods, powerful computers and new computer algorithms. There has been a significantly longer history of sulfide mineral surface research associated with technologists working with, or within, the mining industry. Here, electrochemical methods, sometimes combined with analytical and spectroscopic techniques, have been used to probe surface chemistry. The motivation for this work has been to gain a better understanding of the controls of leaching reactions used to dissolve out metals from ores, or to understand the chemistry of the froth flotation systems used in concentrating the valuable (usually sulfide) minerals prior to metal extraction. The need for improved metal extraction technologies is still a major motivation for research on sulfide surfaces, but in the last couple of decades, new concerns have become important drivers for such work. In particular, much greater awareness of the negative environmental impact of acid and toxic metal-bearing waters derived from breakdown of sulfide minerals at former mining operations has prompted research on oxidation reactions, and on sorption of metals at sulfide surfaces. At the interface between fundamental geochemistry and industrial chemistry, the role of sulfide substrates in catalysis, and in the self-assembly and functionalization of organic molecules, has become an area of

  11. Sulfide Composition and Melt Stability Field in the Earth's Upper Mantle

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Hirschmann, M. M.

    2015-12-01

    In the Earth's upper mantle, sulfur occurs chiefly as (Fe, Ni)xS minerals and melts with near-monosulfide stoichiometries. These could have substantial influence on geochemical and geophysical properties of the Earth's interior. For example, sulfide mineral and melts are the major carriers of chalcophile and platinum group elements (PGEs) and sulfide melts are potentially responsible for mantle geophysical anomalies, as their physical properties (higher density, surface tension, electrical conductivity and lower melting points) differ greatly from those of silicates. Sulfide melts are a potential sink for reduced mantle carbon and perhaps be associated with carbon transport, including diamond precipitation. Sulfides may be molten in large parts of the mantle, but this is determined in part by sulfide composition, which is in turn a product of Fe-Ni exchange with olivine and of the effect of sulfur, oxygen, and carbon fugacities on metal/anion ratios of melts. Melting experiments define the monosulfide (Fe0.35Ni0.12Cu0.01S0.52) solidus from 1-8 GPa at carbon-free and graphite saturated conditions. The resulting carbon-free solidus is below the mantle adiabat to depths of at least 300 km, but does not indicate sulfide melting in continental lithosphere. In contrast, the graphite saturated solidus indicates melting in the lithosphere at 6-7 GPa (~200 km), close to the source conditions typical of diamond formation. To determine the composition of sulfide equilibrated with olivine, we performed experiments on monosulfide-olivine (crushed powders from San Carlos single crystal) under 2 GPa, 1400 ◦C. Our preliminary results suggests that Fe-Ni distribution coefficients KD, defined by (Ni/Fe)sulfide/(Ni/Fe)olivine, have significantly lower values than those determined previously at one atmosphere (Doyle and Naldrett 1987; Fleet and MacRae 1987; Gaetani and Grove 1997). This indicates that sulfide equilibrated with olivine in the mantle is richer in Fe than former

  12. Sulfur and iron speciation in gas-rich impact-melt glasses from basaltic shergottites determined by microXANES

    SciTech Connect

    Sutton, S.R.; Rao, M.N.; Nyquist, L.E.

    2008-04-28

    Sulfur and iron K XANES measurements were made on GRIM glasses from EET 79001. Iron is in the ferrous state. Sulfur speciation is predominately sulfide coordination but is Fe coordinated in Lith B and, most likely, Ca coordinated in Lith A. Sulfur is abundantly present as sulfate near Martian surface based on chemical and mineralogical investigations on soils and rocks in Viking, Pathfinder and MER missions. Jarosite is identified by Moessbauer studies on rocks at Meridian and Gusev, whereas MgSO{sub 4} is deduced from MgO-SO{sub 3} correlations in Pathfinder MER and Viking soils. Other sulfate minerals such as gypsum and alunogen/S-rich aluminosilicates and halides are detected only in martian meteorites such as shergottites and nakhlites using SEM/FE-SEM and EMPA techniques. Because sulfur has the capacity to occur in multiple valence states, determination of sulfur speciation (sulfide/sulfate) in secondary mineral assemblages in soils and rocks near Mars surface may help us understand whether the fluid-rock interactions occurred under oxidizing or reducing conditions. On Earth, volcanic rocks contain measurable quantities of sulfur present as both sulfide and sulfate. Carroll and Rutherford showed that oxidized forms of sulfur may comprise a significant fraction of total dissolved sulfur, if the oxidation state is higher than {approx}2 log fO{sub 2} units relative to the QFM buffer. Terrestrial samples containing sulfates up to {approx}25% in fresh basalts from the Galapagos Rift on one hand and high sulfide contents present in oceanic basalts on the other indicate that the relative abundance of sulfide and sulfate varies depending on the oxygen fugacity of the system. Basaltic shergottites (bulk) such as Shergotty, EET79001 and Zagami usually contain small amounts of sulfur ({approx}0.5%) as pyrrhotite. But, in isolated glass pockets containing secondary salts (known as GRIM glasses) in these meteorites, sulfur is present in high abundance ({approx}1-12%). To

  13. Equilibration of Leachants with Basalt Rock for Repository Simulation Tests

    SciTech Connect

    Jantzen, C.M.

    2001-07-02

    In a nuclear waste repository in basalt, the groundwater will have a low redox potential (Eh) which may affect the leach rate of SRP waste glass. Accurate laboratory simulations of conditions in a basalt reposition must maintain low Eh values throughout the course of the experiment. In this report, important parameters affecting the ability of basalt to maintain appropriate Eh-pH conditions are examined, in particular basalt type and groundwater simulation.

  14. Basaltic injections into floored silicic magma chambers

    NASA Astrophysics Data System (ADS)

    Wiebe, R. A.

    Recent studies have provided compelling evidence that many large accumulations of silicic volcanic rocks erupted from long-lasting, floored chambers of silicic magma that were repeatedly injected by basaltic magma. These basaltic infusions are commonly thought to play an important role in the evolution of the silicic systems: they have been proposed as a cause for explosive silicic eruptions [Sparks and Sigurdsson, 1977], compositional variation in ash-flow sheets [Smith, 1979], mafic magmatic inclusions in silicic volcanic rocks [Bacon, 1986], and mixing of mafic and silicic magmas [Anderson, 1976; Eichelberger, 1978]. If, as seems likely, floored silicic magma chambers have frequently been invaded by basalt, then plutonic bodies should provide records of these events. Although plutonic evidence for mixing and commingling of mafic and silicic magmas has been recognized for many years, it has been established only recently that some intrusive complex originated through multiple basaltic injections into floored chambers of silicic magma [e.g., Wiebe, 1974; Michael, 1991; Chapman and Rhodes, 1992].

  15. Pressure grouting of fractured basalt flows

    SciTech Connect

    Shaw, P.; Weidner, J.; Phillips, S.; Alexander, J.

    1996-04-01

    This report describes a field trial of pressure grouting in basalt and the results of subsequent coring and permeability measurement activities. The objective was to show that the hydraulic conductivity of fractured basalt bedrock can be significantly reduced by pressure injection of cementitious materials. The effectiveness of the pressure grout procedure was evaluated by measuring the change in the hydraulic conductivity of the bedrock. The extent of grout penetration was established by analyzing postgrout injection drilling chips for the presence of a tracer in the grout and also by examining cores of the treated basalt. Downhole radar mapping was used to establish major lava flow patterns and follow water movement during a surface infiltration test. A site called Box Canyon, which is located northwest of the INEL, was chosen for this study due to the similarity of this surface outcrop geology to that of the underlying bedrock fracture system found at the Radioactive Waste Management Complex. This study showed that hydraulic conductivity of basalt can be reduced through pressure grouting of cementitious material.

  16. Thermal models for basaltic volcanism on Io

    USGS Publications Warehouse

    Keszthelyil, L.; McEwen, A.

    1997-01-01

    We present a new model for the thermal emissions from active basaltic eruptions on Io. While our methodology shares many similarities with previous work, it is significantly different in that (1) it uses a field tested cooling model and (2) the model is more applicable to pahoehoe flows and lava lakes than fountain-fed, channelized, 'a'a flows. This model demonstrates the large effect lava porosity has on the surface cooling rate (with denser flows cooling more slowly) and provides a preliminary tool for examining some of the hot spots on Io. The model infrared signature of a basaltic eruption is largely controlled by a single parameter, ??, the average survival time for a lava surface. During an active eruption surfaces are quickly covered or otherwise destroyed and typical values of ?? for a basaltic eruption are expected to be on the order of 10 seconds to 10 minutes. Our model suggests that the Galileo SSI eclipse data are consistent with moderately active to quiescent basaltic lava lakes but are not diagnostic of such activity. Copyright 1997 by the American Geophysical Union.

  17. Hydrogen isotope systematics of submarine basalts

    USGS Publications Warehouse

    Kyser, T.K.; O'Neil, J.R.

    1984-01-01

    The D/H ratios and water contents in fresh submarine basalts from the Mid-Atlantic Ridge, the East Pacific Rise, and Hawaii indicate that the primary D/H ratios of many submarine lavas have been altered by processes including (1) outgassing, (2) addition of seawater at magmatic temperature, and (3) low-temperature hydration of glass. Decreases in ??D and H2O+ from exteriors to interiors of pillows are explained by outgassing of water whereas inverse relations between ??D and H2O+ in basalts from the Galapagos Rise and the FAMOUS Area are attributed to outgassing of CH4 and H2. A good correlation between ??D values and H2O is observed in a suite of submarine tholeiites dredged from the Kilauea East Rift Zone where seawater (added directly to the magma), affected only the isotopic compositions of hydrogen and argon. Analyses of some glassy rims indicate that the outer millimeter of the glass can undergo lowtemperature hydration by hydroxyl groups having ??D values as low as -100. ??D values vary with H2O contents of subaerial transitional basalts from Molokai, Hawaii, and subaerial alkali basalts from the Society Islands, indicating that the primary ??D values were similar to those of submarine lavas. Extrapolations to possible unaltered ??D values and H2O contents indicate that the primary ??D values of most thoteiite and alkali basalts are near -80 ?? 5: the weight percentages of water are variable, 0.15-0.35 for MOR tholeiites, about 0.25 for Hawaiian tholeiites, and up to 1.1 for alkali basalts. The primary ??D values of -80 for most basalts are comparable to those measured for deep-seated phlogopites. These results indicate that hydrogen, in marked contrast to other elements such as Sr, Nd, Pb, and O, has a uniform isotopic composition in the mantle. This uniformity is best explained by the presence of a homogeneous reservoir of hydrogen that has existed in the mantle since the very early history of the Earth. ?? 1984.

  18. Geophysical Signatures to Monitor Fluids and Mineralization for CO2 Sequestration in Basalts

    NASA Astrophysics Data System (ADS)

    Otheim, L. T.; Adam, L.; Van Wijk, K.; Batzle, M. L.; Mcling, T. L.; Podgorney, R. K.

    2011-12-01

    Carbon dioxide sequestration in large reservoirs can reduce emissions of this green house gas into the atmosphere. Basalts are promising host rocks due to their volumetric extend, worldwide distribution, and recent observations that CO2-water mixtures react with basalt minerals to precipitate as carbonate minerals, trapping the CO2. The chemical reaction between carbonic acid and minerals rich in calcium, magnesium and iron precipitates carbonates in the pore space. This process would increase the elastic modulus and velocity of the rock. At the same time, the higher compressibility of CO2 over water changes the elastic properties of the rock, decreasing the saturated rock bulk modulus and the P-wave velocity. Reservoirs where the rock properties change as a result of fluid or pressure changes are commonly monitored with seismic methods. Here we present experiments to study the feasibility of monitoring CO2 migration in a reservoir and CO2-rock reactions for a sequestration scenario in basalts. Our goal is to measure the rock's elastic response to mineralization with non-contacting ultrasonic lasers, and the effect of fluid substitution at reservoir conditions at seismic and ultrasonic frequencies. For the fluid substitution experiment we observe changes in the P- and S-wave velocities when saturating the sample with super-critical (sc) CO2, CO2-water mixtures and water alone for different pore and confining pressures. The bulk modulus of the rock is significantly dependent on frequency in the 2~to 106~Hz range, for CO2-water mixtures and pure water saturations. Dry and pure CO2 (sc or gas) do not show a frequency dependence on the modulus. Moreover, the shear wave modulus is not dispersive for either fluid. The frequency dependence of the elastic parameters is related to the attenuation (1/Q) of the rock. We will show the correlation between frequency dependent moduli and attenuation data for the different elastic moduli of the rocks. Three other basalt samples

  19. Coatings on Atacama Desert Basalt: A Possible Analog for Coatings on Gusev Plains Basalt

    NASA Technical Reports Server (NTRS)

    Sutter, B.; Golden, D. C.; Amundson, R.; Chong-Diaz, G.; Ming, D. W.

    2007-01-01

    Surface coatings on Gusev Plains basalt have been observed and may contain hematite and nanophase Fe-oxides along with enrichments in P, S, Cl, and K relative to the underlying rock. The Gusev coatings may be derived from the dissolution of adhering soil and/or parent rock along with the addition of S and Cl from outside sources. Transient water for dissolution could be sourced from melting snow during periods of high obliquity, acid fog, and/or ground water (Haskin et al., 2005). Coatings on basalt in the hyper-arid (less than 2mm y(sup -1)) Atacama Desert may assist in understanding the chemistry, mineralogy and formation mechanisms of the Gusev basalt coatings. The Atacama Desert climate is proposed to be analogous to a paleo-Mars climate that was characterized by limited aqueous activity when the Gusev coatings could have formed. The objectives of this work are to (i) determine the chemical nature and extent of surface coatings on Atacama Desert basalt, and (ii) assess coating formation mechanisms in the Atacama Desert. Preliminary backscattered electron imaging of Atacama basalt thin-sections indicated that the coatings are as thick as 20 m. The boundary between the coating and the basalt labradorite, ilmenite, and augite grains was abrupt indicating that the basalt minerals underwent no chemical dissolution. The Atacama coatings have been added to the basalt instead of being derived from basalt chemical weathering. Semi-quantitative energy dispersive spectroscopy shows the coatings to be chemically homogeneous. The coating is depleted in Ca (0.9 wt% CaO) and enriched in K (1.3 wt.% K2O) and Si (69.1 wt.% SiO2) relative to the augite and labradorite grains. A dust source enriched in Si (e.g., poorly crystalline silica) and K and depleted in Ca appears to have been added to the basalt surface. Unlike the Gusev coatings, no P, S, and Cl enrichment was observed. However, Fe (3.2 wt.% FeO) was present in the Atacama coatings suggesting the present of Fe

  20. Variable mineralization processes during the formation of the Permian Hulu Ni-Cu sulfide deposit, Xinjiang, Northwestern China

    NASA Astrophysics Data System (ADS)

    Zhao, Yun; Xue, Chunji; Zhao, Xiaobo; Yang, Yongqiang; Ke, Junjun; Zu, Bo

    2016-08-01

    The Permian Hulu Ni-Cu sulfide deposit is located at the southern margin of the Central Asian Orogenic Belt (CAOB) in Northern Xinjiang, Northwestern China. The host intrusion of the Hulu deposit is composed of a layered mafic-ultramafic sequence and a dike-like unit. The layered sequence is composed of harzburgite, lherzolite, pyroxenite, gabbro, gabbrodiorite and diorite. The dike-like body comprises lherzolite and gabbro. Sulfide orebodies occur mainly within the harzburgite, pyroxenite and lherzolite at the base of the layered sequence and within the lherzolite in the dike-like body. Sulfide mineralization from the Hulu deposit shows significant depletion of PGE relative to Cu and Ni. These elements show good positive correlations with S in the sulfide mineralization from the dike-like unit but relatively weak correlations in the sulfide mineralization from the layered sequence. The sulfide mineralization from the layered unit shows excellent positive correlations between Ir and Os, Ru or Rh, and poor relationships between Ir and Pt or Pd. On the contrary, sulfide mineralization from the dike-like unit shows good correlations in the diagrams of Os, Ru, Rh, Pt and Pd against Ir. Both high Cu/Pd ratios (8855-481,398) and our modeling indicate that PGE depletion resulted from sulfide removal in a deep staging magma chamber. The evolved PGE-depleted magmas then ascended to the shallower magma chamber and became sulfide saturation due to crustal contamination. Both low Se/S ratios (33.5 × 10-6-487.5 × 10-6) and a negative correlation between Se/S and Cu/Pd ratios are consistent with the addition of crustal S. A large number of sulfide liquids segregated with minor crystallization of monosulfide solid solution (MSS) in the shallower magma chamber. When new magma pulses with unfractionated sulfide droplets entered the shallower magma chamber, the sulfide slurry containing crystallized MSS may be disrupted and mixed with the unfractionated sulfide droplets. The

  1. H 2O in basalt and basaltic andesite glass inclusions from four subduction-related volcanoes

    NASA Astrophysics Data System (ADS)

    Sisson, T. W.; Layne, G. D.

    1993-06-01

    Total dissolved H 2O and major element abundances were measured in basalt and basaltic andesite glass inclusions in olivine phenocrysts from Quaternary eruptions of four subduction-related volcanoes to test the hypothesis that low-MgO high-alumina basalts contain high H 2O at depth [1] and to reveal any petrogenetically significant correlations between arc basalt compositions and H 2O contents. Total dissolved H 2O (combined molecular H 2O and OH groups) measured by ion microprobe in mafic glass inclusions from the 1974 eruption of Fuego, Guatemala, reaches 6.2 wt.%. Dissolved H 2O contents decrease in more evolved Fuego glasses. Correlations of H 2O with MgO, Na 2O, K 2O, S and Cl indicate that aqueous fluid exsolution during magma ascent forced crystallization and differentiation of residual liquids. Low-K 2O magnesian high-alumina basalt glass inclusions from the 3 ka eruption of Black Crater (Medicine Lake volcano, California) have low H 2O contents, near 0.2 wt.%, which are consistent with the MORB-like character of these and other primitive lavas of the Medicine Lake region. Basalt and basaltic andesite glass inclusions from Copco Cone and Goosenest volcano on the Cascade volcanic front north of Mt. Shasta have H 2O contents of up to 3.3 wt.%. The range of H 2O contents in Cascade mafic magmas is too large to have resulted solely from enrichment by crystallization and indicates the participation of an H 2O-rich component in magma generation or crustal-level modification. Whereas fluid-absent melting of amphibole-bearing peridotite can account for the H 2O in most mafic arc liquids, the very high H 2O/alkali ratios of the 1974 Fuego eruptives suggest that an aqueous fluid was involved in the generation of Fuego basalts.

  2. Sulfur isotope homogeneity of lunar mare basalts

    NASA Astrophysics Data System (ADS)

    Wing, Boswell A.; Farquhar, James

    2015-12-01

    We present a new set of high precision measurements of relative 33S/32S, 34S/32S, and 36S/32S values in lunar mare basalts. The measurements are referenced to the Vienna-Canyon Diablo Troilite (V-CDT) scale, on which the international reference material, IAEA-S-1, is characterized by δ33S = -0.061‰, δ34S ≡ -0.3‰ and δ36S = -1.27‰. The present dataset confirms that lunar mare basalts are characterized by a remarkable degree of sulfur isotopic homogeneity, with most new and published SF6-based sulfur isotope measurements consistent with a single mass-dependent mean isotopic composition of δ34S = 0.58 ± 0.05‰, Δ33S = 0.008 ± 0.006‰, and Δ36S = 0.2 ± 0.2‰, relative to V-CDT, where the uncertainties are quoted as 99% confidence intervals on the mean. This homogeneity allows identification of a single sample (12022, 281) with an apparent 33S enrichment, possibly reflecting cosmic-ray-induced spallation reactions. It also reveals that some mare basalts have slightly lower δ34S values than the population mean, which is consistent with sulfur loss from a reduced basaltic melt prior to eruption at the lunar surface. Both the sulfur isotope homogeneity of the lunar mare basalts and the predicted sensitivity of sulfur isotopes to vaporization-driven fractionation suggest that less than ≈1-10% of lunar sulfur was lost after a potential moon-forming impact event.

  3. A Reaction Involving Oxygen and Metal Sulfides.

    ERIC Educational Resources Information Center

    Hill, William D. Jr.

    1986-01-01

    Describes a procedure for oxygen generation by thermal decomposition of potassium chlorate in presence of manganese dioxide, reacted with various sulfides. Provides a table of sample product yields for various sulfides. (JM)

  4. Does the presence of bacteria effect basaltic glass dissolution rates? 1: Dead Pseudomonas reactants

    NASA Astrophysics Data System (ADS)

    Stockmann, Gabrielle J.; Shirokova, Liudmila S.; Pokrovsky, Oleg S.; Oelkers, Eric H.; Benezeth, Pascale

    2010-05-01

    Basaltic glass and crystalline basalt formations in Iceland have been suggested for industrial CO2 storage due to their porous and permeable properties and high reactivity. Acid CO2-saturated waters in contact with basaltic glass will lead to rapid dissolution of the glass and release of divalent cations, (Ca2+, Mg2+, Fe2+) that can react to form stable carbonates and thereby trap the CO2. However, the basalt formations in Iceland not only contains glass and mineral assemblages, but also host microbiological communities that either by their presence or by active involvement in chemical reactions could affect the amount of basaltic glass being dissolved and CO2 being trapped. Samples of natural bacteria communities from the CO2 storage grounds in Iceland were collected, separated, and purified using agar plate technique and cultured under laboratory conditions in nutrient broth-rich media. Heterotrophic aerobic Gram-negative strain of Pseudomonas reactants was selected for a series of flow-through experiments aimed at evaluation of basaltic glass dissolution rate in the presense of increasing amounts of dead bacteria and their lysis products. The experiments were carried out using mixed-flow reactors at pH 4, 6, 8 and 10 at 25 °C. Each of the four reactors contained 1 gram of basaltic glass of the size fraction 45-125 μm. This glass was dissolved in ~ 0.01 M buffer solutions (acetate, MES, bicarbonate and carbonate+bicarbonate mixture) of the desired pH. All experiments ran 2 months, keeping the flowrate and temperature stable and only changing the concentration of dead bacteria in the inlet solutions (from 0 to 430 mg/L). Experiments were performed in sterile conditions, and bacterial growth was prevented by adding NaN3 to the inlet solutions. Routine culturing of bacteria on the agar plates confirmed the sterility of experiments. Samples of outlet solutions were analyzed for major cations and trace elements by ICP-MS. Results demonstrate a slight decrease in the

  5. Lead Isotopic Compositions of the Endeavour Sulfides, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Labonte, F.; Hannington, M. D.; Cousens, B. L.; Blenkinsop, J.; Gill, J. B.; Kelley, D. S.; Lilley, M. D.; Delaney, J. R.

    2006-12-01

    reference line for the northern hemisphere mantle reservoirs in plots of 206Pb/204Pb versus 207Pb/204Pb and 208Pb/204Pb, suggesting relatively little contribution from buried sediment compared to deposits at sedimented ridges. Alternatively, systematic differences in the Pb isotope compositions of sulfides along the length of the ridge segment could be attributed to variable leaching of previously altered basaltic crust or interaction between hydrothermal fluids and enriched Mid-Ocean Ridge Basalts (MORB) sources.

  6. Mineralizing conditions and source fluid composition of base metal sulfides in the Lon District, southeastern Iceland

    NASA Astrophysics Data System (ADS)

    Kremer, C. H.; Thomas, D.; García del Real, P.; Zierenberg, R. A.; Bird, D. K.

    2014-12-01

    Hydrothermal base metal mineralization is rare in Iceland due to the scarcity of evolved magma bodies that discharge metal-rich aqueous fluids into bedrock. One exception is the Lon District of southeastern Iceland, where explosively emplaced rhyolitic breccias host base metal sulfide minerals. We performed petrographic, fluid inclusion, and stable isotope analyses on samples collected in Lon to constrain the conditions of sulfide mineral formation. Based on outcrop and hand sample observations, hot, early-stage hydrothermal fluids precipitated sulfide minerals, quartz, and epidote in rhyolitic breccia and basalt flows. Cooler late-stage fluids precipitated carbonates and quartz in rhyolitic breccia and basalt flows. The order of precipitation of the sulfides was: galena, sphalerite, then chalcopyrite. Homogenization temperatures of liquid-dominated multi-phase fluid inclusions in hydrothermal early-stage quartz coeval with chalcopyrite cluster around 303 °C and 330 °C, indicating precipitation of metallic sulfides in two main hydrothermal fluid pulses early in the period of hydrothermal activity in the Lon District. Freezing point depression analyses of fluid inclusions in quartz show that the sulfide minerals precipitated from a solution that was 4 wt. % NaCl. The 𝛿34S values of sulfides indicate that early-stage hydrothermal sulfur was derived from igneous rocks, either through leaching by non-magmatic hydrothermal fluids or by exsolution of magmatic waters. Early stage epidote 𝛿D values were on average -65.96 per mil, about 14 per mil higher than reported values in epidotes from elsewhere in southeastern Iceland. The 𝛿13C and 𝛿18O values of late-stage carbonates indicate that late stage hydrothermal fluids were meteoric in origin. Collectively, fluid inclusion and stable isotope analyses suggest that early-stage aqueous fluids derived from a mixture of magmatic waters exsolved from the proximal Geitafell intrusion and meteoric

  7. Nickel sulfide hollow whisker formation

    SciTech Connect

    Holcomb, G.R.; Cramer, S.D.

    1997-02-01

    Hollow, high-aspect-ratio nickel sulfide whiskers were formed during aqueous corrosion experiments at 250 C by the US Department of Energy. The whiskers grew radially from Teflon thread at the waterline in acidic sodium sulfate solutions containing chloride additions. The hollow morphology is consistent with that reported for the mineral millerite found in nature in hematite cavities. The data suggest that iron and chloride impurities are necessary for the observed whisker structure. Hollow nickel sulfide whiskers were observed only in high-temperature corrosion experiments conducted on stainless steels; they were not observed in similar experiments on nickel-base alloys.

  8. Effect of Fluorine on Near-Liquidus Phase Equilibria of Basalts

    NASA Technical Reports Server (NTRS)

    Filiberto, Justin; Wood, Justin; Loan, Le; Dasgupta, Rajdeep; Shimizu, Nobumichi; Treiman, Allan H.

    2010-01-01

    Volatile species such as H2O, CO2, F, and Cl have significant impact in generation and differentiation of basaltic melts. Thus far experimental work has primarily focused on the effect of water and carbon dioxide on basalt crystallization, liquid-line of descent, and mantle melting [e.g., 1, 2] and the effects of halogens have received far less attention [3-4]. However, melts in the planetary interiors can have non-negligible chlorine and fluorine concentrations. Here, we explore the effects of fluorine on near-liquidus phase equilibria of basalt. We have conducted nominally anhydrous piston cylinder experiments using graphite capsules at 0.6 - 1.5 GPa on an Fe-rich model basalt composition. 1.75 wt% fluorine was added to the starting mix in the form of AgF2. Fluorine in the experimental glass was measured by SIMS and major elements of glass and minerals were analyzed by EPMA. Nominally volatile free experiments yield a liquidus temperature from 1330 C at 0.8GPa to 1400 at 1.6GPa and an olivine(Fo72)-pyroxene(En68)-liquid multiple saturation point at 1.25 GPa and 1375 C. The F-bearing experiments yield a liquiudus temperature from 1260 C at 0.6GPa to 1305 at 1.5GPa and an ol(Fo66)-pyx(En64)-MSP at 1 GPa and 1260 C. This shows that F depresses the basalt liquidus, extends the pyroxene stability field to lower pressure, and forces the liquidus phases to be more Fe-rich. KD(Fe-Mg/mineral-melt) calculated for both pyroxenes and olivines show an increase with increasing F content of the melt. Therefore, we infer that F complexes with Mg in the melt and thus increases the melt s silica activity, depressing the liquidus and changing the composition of the crystallizing minerals. Our study demonstrates that on a weight percent basis, the effect of fluorine is similar to the effect of H2O [1] and Cl [3] on freezing point depression of basalts. But on an atomic fraction basis, the effect of F on liquidus depression of basalts is xxxx compared to the effect of H. Future

  9. Molybdenite saturation in silicic magmas: Occurrence and petrological implications

    USGS Publications Warehouse

    Audetat, A.; Dolejs, D.; Lowenstern, J. B.

    2011-01-01

    We identified molybdenite (MoS2) as an accessory magmatic phase in 13 out of 27 felsic magma systems examined worldwide. The molybdenite occurs as small (<20 ??m) triangular or hexagonal platelets included in quartz phenocrysts. Laser-ablation inductively coupled plasma mass spectrometry analyses of melt inclusions in molybdenite-saturated samples reveal 1-13 ppm Mo in the melt and geochemical signatures that imply a strong link to continental rift basalt-rhyolite associations. In contrast, arc-associated rhyolites are rarely molybdenite-saturated, despite similar Mo concentrations. This systematic dependence on tectonic setting seems to reflect the higher oxidation state of arc magmas compared with within-plate magmas. A thermodynamic model devised to investigate the effects of T, f O2 and f S2 on molybdenite solubility reliably predicts measured Mo concentrations in molybdenite-saturated samples if the magmas are assumed to have been saturated also in pyrrhotite. Whereas pyrrhotite microphenocrysts have been observed in some of these samples, they have not been observed from other molybdenite-bearing magmas. Based on the strong influence of f S2 on molybdenite solubility we calculate that also these latter magmas must have been at (or very close to) pyrrhotite saturation. In this case the Mo concentration of molybdenite-saturated melts can be used to constrain both magmatic f O2 and f S2 if temperature is known independently (e.g. by zircon saturation thermometry). Our model thus permits evaluation of magmatic f S2, which is an important variable but is difficult to estimate otherwise, particularly in slowly cooled rocks. ?? The Author 2011. Published by Oxford University Press. All rights reserved.

  10. 30 CFR 250.604 - Hydrogen sulfide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.604 Section 250.604... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Workover Operations § 250.604 Hydrogen sulfide. When a well-workover operation is conducted in zones known to contain hydrogen sulfide (H2S) or...

  11. 30 CFR 250.504 - Hydrogen sulfide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.504 Section 250.504... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Well-Completion Operations § 250.504 Hydrogen sulfide. When a well-completion operation is conducted in zones known to contain hydrogen sulfide (H2S) or...

  12. 30 CFR 250.808 - Hydrogen sulfide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Hydrogen sulfide. 250.808 Section 250.808... OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Production Safety Systems § 250.808 Hydrogen sulfide. Production operations in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of...

  13. Nanostructured metal sulfides for energy storage.

    PubMed

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-09-01

    Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices. PMID:25073046

  14. Nanostructured metal sulfides for energy storage.

    PubMed

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-09-01

    Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices.

  15. 30 CFR 250.808 - Hydrogen sulfide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 2 2012-07-01 2012-07-01 false Hydrogen sulfide. 250.808 Section 250.808 Mineral Resources BUREAU OF SAFETY AND ENVIRONMENTAL ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE OIL... § 250.808 Hydrogen sulfide. Production operations in zones known to contain hydrogen sulfide (H2S) or...

  16. 30 CFR 250.604 - Hydrogen sulfide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 2 2011-07-01 2011-07-01 false Hydrogen sulfide. 250.604 Section 250.604...-Workover Operations § 250.604 Hydrogen sulfide. When a well-workover operation is conducted in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of H2S is unknown (as defined...

  17. 30 CFR 250.504 - Hydrogen sulfide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 2 2011-07-01 2011-07-01 false Hydrogen sulfide. 250.504 Section 250.504...-Completion Operations § 250.504 Hydrogen sulfide. When a well-completion operation is conducted in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of H2S is unknown (as defined...

  18. 30 CFR 250.808 - Hydrogen sulfide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 2 2014-07-01 2014-07-01 false Hydrogen sulfide. 250.808 Section 250.808 Mineral Resources BUREAU OF SAFETY AND ENVIRONMENTAL ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE OIL... § 250.808 Hydrogen sulfide. Production operations in zones known to contain hydrogen sulfide (H2S) or...

  19. 30 CFR 250.808 - Hydrogen sulfide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 2 2013-07-01 2013-07-01 false Hydrogen sulfide. 250.808 Section 250.808 Mineral Resources BUREAU OF SAFETY AND ENVIRONMENTAL ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE OIL... § 250.808 Hydrogen sulfide. Production operations in zones known to contain hydrogen sulfide (H2S) or...

  20. Nanostructured metal sulfides for energy storage

    NASA Astrophysics Data System (ADS)

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-08-01

    Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices.

  1. Basalt Reactivity Variability with Reservoir Depth in Supercritical CO2 and Aqueous Phases

    SciTech Connect

    Schaef, Herbert T.; McGrail, B. Peter; Owen, Antionette T.

    2011-04-01

    Long term storage of CO{sub 2} in geologic formations is currently considered the most attractive option to reduce greenhouse gas emissions while continuing to utilize fossil fuels for energy production. Injected CO{sub 2} is expected to reside as a buoyant water-saturated supercritical fluid in contact with reservoir rock, the caprock system, and related formation waters. As was reported for the first time at the GHGT-9 conference, experiments with basalts demonstrated surprisingly rapid carbonate mineral formation occurring with samples suspended in the scCO{sub 2} phase. Those experiments were limited to a few temperatures and CO{sub 2} pressures representing relatively shallow (1 km) reservoir depths. Because continental flood basalts can extend to depths of 5 km or more, in this paper we extend the earlier results across a pressure-temperature range representative of these greater depths. Different basalt samples, including well cuttings from the borehole used in a pilot-scale basalt sequestration project (Eastern Washington, U.S.) and core samples from the Central Atlantic Magmatic Province (CAMP), were exposed to aqueous solutions in equilibrium with scCO{sub 2} and water-rich scCO{sub 2} at six different pressures and temperatures for select periods of time (30 to 180 days). Conditions corresponding to a shallow injection of CO{sub 2} (7.4 MPa, 34 C) indicate limited reactivity with basalt; surface carbonate precipitates were not easily identified on post-reacted basalt grains. Basalts exposed under identical times appeared increasingly more reacted with simulated depths. Tests, conducted at higher pressures (12.0 MPa) and temperatures (55 C), reveal a wide variety of surface precipitates forming in both fluid phases. Under shallow conditions tiny clusters of aragonite needles began forming in the wet scCO{sub 2} fluid, whereas in the CO{sub 2} saturated water, cation substituted calcite developed thin radiating coatings. Although these types of coatings

  2. Saturated Zone Colloid Transport

    SciTech Connect

    H. S. Viswanathan

    2004-10-07

    This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, R{sub col} is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh, and ionic strength). These factors are folded into the distributions of R{sub col} that have been developed from field and experimental data collected under varying geochemical conditions with different colloid types and sizes. Attachment rate constants, k{sub att}, and detachment rate constants, k{sub det}, of colloids to the fracture surface have been measured for the fractured volcanics, and separate R{sub col} uncertainty distributions have been developed for attachment and detachment to clastic material and mineral grains in the alluvium. Radionuclides such as plutonium and americium sorb mostly (90 to 99 percent) irreversibly to colloids (BSC 2004 [DIRS 170025], Section 6.3.3.2). The colloid retardation factors developed in this analysis are needed to simulate the transport of radionuclides that are irreversibly sorbed onto colloids; this transport is discussed in the model report ''Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]). Although it is not exclusive to any particular radionuclide release scenario, this scientific analysis especially addresses those scenarios pertaining to evidence from waste-degradation experiments, which indicate that plutonium and americium may be irreversibly attached to colloids for the time scales of interest. A section of this report will also discuss the validity of using microspheres as analogs to colloids in some of the lab and field experiments used to obtain the colloid retardation factors. In addition, a small fraction of colloids travels with the groundwater without any significant retardation

  3. Additive Construction using Basalt Regolith Fines

    NASA Technical Reports Server (NTRS)

    Mueller, Robert P.; Sibille, Laurent; Hintze, Paul E.; Lippitt, Thomas C.; Mantovani, James G.; Nugent, Matthew W.; Townsend, Ivan I.

    2014-01-01

    Planetary surfaces are often covered in regolith (crushed rock), whose geologic origin is largely basalt. The lunar surface is made of small-particulate regolith and areas of boulders located in the vicinity of craters. Regolith composition also varies with location, reflecting the local bedrock geology and the nature and efficiency of the micrometeorite-impact processes. In the lowland mare areas (suitable for habitation), the regolith is composed of small granules (20 - 100 microns average size) of mare basalt and volcanic glass. Impacting micrometeorites may cause local melting, and the formation of larger glassy particles, and this regolith may contain 10-80% glass. Studies of lunar regolith are traditionally conducted with lunar regolith simulant (reconstructed soil with compositions patterned after the lunar samples returned by Apollo). The NASA Kennedy Space Center (KSC) Granular Mechanics & Regolith Operations (GMRO) lab has identified a low fidelity but economical geo-technical simulant designated as Black Point-1 (BP-1). It was found at the site of the Arizona Desert Research and Technology Studies (RATS) analog field test site at the Black Point lava flow in adjacent basalt quarry spoil mounds. This paper summarizes activities at KSC regarding the utilization of BP-1 basalt regolith and comparative work with lunar basalt simulant JSC-1A as a building material for robotic additive construction of large structures. In an effort to reduce the import or in-situ fabrication of binder additives, we focused this work on in-situ processing of regolith for construction in a single-step process after its excavation. High-temperature melting of regolith involves techniques used in glassmaking and casting (with melts of lower density and higher viscosity than those of metals), producing basaltic glass with high durability and low abrasive wear. Most Lunar simulants melt at temperatures above 1100 C, although melt processing of terrestrial regolith at 1500 C is not

  4. Geology, sulfide geochemistry and supercritical venting at the Beebe Hydrothermal Vent Field, Cayman Trough

    NASA Astrophysics Data System (ADS)

    Webber, Alexander P.; Roberts, Stephen; Murton, Bramley J.; Hodgkinson, Matthew R. S.

    2015-09-01

    The Beebe Vent Field (BVF) is the world's deepest known hydrothermal system, at 4960 m below sea level. Located on the Mid-Cayman Spreading Centre, Caribbean, the BVF hosts high temperature (˜401°C) "black smoker" vents that build Cu, Zn and Au-rich sulfide mounds and chimneys. The BVF is highly gold-rich, with Au values up to 93 ppm and an average Au:Ag ratio of 0.15. Gold precipitation is directly associated with diffuse flow through "beehive" chimneys. Significant mass-wasting of sulfide material at the BVF, accompanied by changes in metal content, results in metaliferous talus and sediment deposits. Situated on very thin (2-3 km thick) oceanic crust, at an ultraslow spreading centre, the hydrothermal system circulates fluids to a depth of ˜1.8 km in a basement that is likely to include a mixture of both mafic and ultramafic lithologies. We suggest hydrothermal interaction with chalcophile-bearing sulfides in the mantle rocks, together with precipitation of Au in beehive chimney structures, has resulted in the formation of a Au-rich volcanogenic massive sulfide (VMS) deposit. With its spatial distribution of deposit materials and metal contents, the BVF represents a modern day analogue for basalt hosted, Au-rich VMS systems.

  5. Correlation between compositions of ore and host rocks in volcanogenic massive sulfide deposits of the Southern Urals

    NASA Astrophysics Data System (ADS)

    Seravkin, I. B.

    2013-05-01

    The geology and typification of volcanogenic massive sulfide (VMS) deposits of the Southern Urals are considered. The mineralogical-geochemical types of these deposits correlate with the composition of the underlying igneous rocks: Ni-Co-Cu deposits correlatedwith serpentinites (Ivanovka type); (Co)-Cu deposits, with basalts (Dombarovka type); Cu-Zn deposits, with basalt-rhyolite and basalt-andesite-rhyolite complexes (Ural type); and Au-Ba-Pb-Zn-Cu deposits, with basalt-andesite-rhyolite complexes with predominance of andesitic and felsic volcanics (Baimak type). The Ural-type deposits are subdivided into three subtypes: I, underlain by basalts (Zn-Cu deposits); II, hosted in felsic volcanic rocks of bimodal complexes (Cu-Zn deposits); and III, hosted in felsic volcanic rocks of continuously differentiated complexes (Zn-Cu deposits with Ba, Pb, and As). The above types and subtypes bearing local names are compared with global types of VMS deposits (MAR, Cyprus, Noranda, and Kuroko), to which they are close but not identical.

  6. Chalcophile element partitioning between sulfide phases and hydrous mantle melt: Applications to mantle melting and the formation of ore deposits

    NASA Astrophysics Data System (ADS)

    Li, Yuan

    2014-11-01

    Understanding the geochemical behavior of chalcophile elements in magmatic processes is hindered by the limited partition coefficients between sulfide phases and silicate melt, in particular at conditions relevant to partial melting of the hydrated, metasomatized upper mantle. In this study, the partitioning of elements Co, Ni, Cu, Zn, As, Mo, Ag, and Pb between sulfide liquid, monosulfide solid solution (MSS), and hydrous mantle melt has been investigated at 1200 °C/1.5 GPa and oxygen fugacity ranging from FMQ-2 to FMQ+1 in a piston-cylinder apparatus. The determined partition coefficients between sulfide liquid and hydrous mantle melt are: 750-1500 for Cu; 600-1200 for Ni; 35-42 for Co; 35-53 for Pb; and 1-2 for Zn, As, and Mo. The partition coefficients between MSS and hydrous mantle melt are: 380-500 for Cu; 520-750 for Ni; ∼50 for Co; <0.5 for Zn; 0.3-6 for Pb; 0.1-2 for As; 1-2 for Mo; and >34 for Ag. The variation of the data is primarily due to differences in oxygen fugacity. These partitioning data in conjunction with previous data are applied to partial melting of the upper mantle and the formation of magmatic-hydrothermal Cu-Au deposits and magmatic sulfide deposits. I show that the metasomatized arc mantle may no longer contain sulfide after >10-14% melt extraction but is still capable of producing the Cu concentrations in the primitive arc basalts, and that the comparable Cu concentrations in primitive arc basalts and in MORB do not necessarily imply similar oxidation states in their source regions. Previous models proposed for producing Cu- and/or Au-rich magmas have been reassessed, with the conclusions summarized as follows. (1) Partial melting of the oxidized (fO2 > FMQ), metasomatized arc mantle with sulfide exhaustion at degrees >10-14% may not generate Cu-rich, primitive arc basalts. (2) Partial melting of sulfide-bearing cumulates in the root of thickened lower continental crust or lithospheric mantle does not typically generate Cu- and

  7. Geochemistry of apollo 15 basalt 15555 and soil 15531.

    PubMed

    Schnetzler, C C; Philpotts, J A; Nava, D F; Schuhmann, S; Thomas, H H

    1972-01-28

    Major and trace element concentrations have been determined by atomic absorption spectrophotometry, colorimetry, and isotope dilution in Apollo 15 mare basalt 15555 from the Hadley Rille area; trace element concentrations have also been determined in plagioclase and pyroxene separates from basalt 15555 and in soil 15531 from the same area. Basalt 15555 most closely resembles in composition the Apollo 12 olivine-rich basalts. The concentrations of lithium, potassium, rubidium, barium, rare-earth elements, and zirconium in basalt 15555 are the lowest, and the negative europium anomaly is the smallest, reported for lunar basalts; this basalt might be the least differentiated material yet returned from the moon. Crystallization and removal of about 6 percent of plagioclase similar to that contained in the basalt would account for the observed europium anomaly; if plagioclase is not on the liquidus of this basalt, a multistage origin is indicated. Mineral data indicate that plagioclase and pyroxene approached quasi-equilibrium. Most of the chemical differences between basalt 15555 and soil 15531 would be accounted for if the soil were a mixture of 88 percent basalt, 6 percent KREEP (a component, identified in other Apollo soils, rich in potassium, rare-earth elements, and phosphorus) and 6 percent plagioclase (anorthosite?). PMID:17731364

  8. Geochemistry of apollo 15 basalt 15555 and soil 15531.

    PubMed

    Schnetzler, C C; Philpotts, J A; Nava, D F; Schuhmann, S; Thomas, H H

    1972-01-28

    Major and trace element concentrations have been determined by atomic absorption spectrophotometry, colorimetry, and isotope dilution in Apollo 15 mare basalt 15555 from the Hadley Rille area; trace element concentrations have also been determined in plagioclase and pyroxene separates from basalt 15555 and in soil 15531 from the same area. Basalt 15555 most closely resembles in composition the Apollo 12 olivine-rich basalts. The concentrations of lithium, potassium, rubidium, barium, rare-earth elements, and zirconium in basalt 15555 are the lowest, and the negative europium anomaly is the smallest, reported for lunar basalts; this basalt might be the least differentiated material yet returned from the moon. Crystallization and removal of about 6 percent of plagioclase similar to that contained in the basalt would account for the observed europium anomaly; if plagioclase is not on the liquidus of this basalt, a multistage origin is indicated. Mineral data indicate that plagioclase and pyroxene approached quasi-equilibrium. Most of the chemical differences between basalt 15555 and soil 15531 would be accounted for if the soil were a mixture of 88 percent basalt, 6 percent KREEP (a component, identified in other Apollo soils, rich in potassium, rare-earth elements, and phosphorus) and 6 percent plagioclase (anorthosite?).

  9. Platinum metals magmatic sulfide ores.

    PubMed

    Naldrett, A J; Duke, J M

    1980-06-27

    Platinum-group elements (PGE) are mined predominantly from deposits that have formed by the segregation of molten iron-nickel-copper sulfides from silicate magmas. The absolute concentrations of PGE in sulfides from different deposits vary over a range of five orders of magnitude, whereas those of other chalcophile elements vary by factors of only 2 to 100. However, the relative proportions of the different PGE in a given deposit are systematically related to the nature of the parent magma. The absolute and relative concentrations of PGE in magmatic sulfides are explained in terms of the degree of partial melting of mantle peridotite required to produce the parent magma and the processes of batch equilibration and fractional segregation of sulfides. The Republic of South Africa and the U.S.S.R. together possess more than 97 percent of the world PGE reserves, but significant undeveloped resources occur in North America. The Stillwater complex in Montana is perhaps the most important example. PMID:17796685

  10. p-Chlorophenyl methyl sulfide

    Integrated Risk Information System (IRIS)

    p - Chlorophenyl methyl sulfide ; CASRN 123 - 09 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for N

  11. Transition metal sulfide loaded catalyst

    DOEpatents

    Maroni, V.A.; Iton, L.E.; Pasterczyk, J.W.; Winterer, M.; Krause, T.R.

    1994-04-26

    A zeolite-based catalyst is described for activation and conversion of methane. A zeolite support includes a transition metal (Mo, Cr or W) sulfide disposed within the micropores of the zeolite. The catalyst allows activation and conversion of methane to C[sub 2]+ hydrocarbons in a reducing atmosphere, thereby avoiding formation of oxides of carbon.

  12. Transition metal sulfide loaded catalyst

    DOEpatents

    Maroni, Victor A.; Iton, Lennox E.; Pasterczyk, James W.; Winterer, Markus; Krause, Theodore R.

    1994-01-01

    A zeolite based catalyst for activation and conversion of methane. A zeolite support includes a transition metal (Mo, Cr or W) sulfide disposed within the micropores of the zeolite. The catalyst allows activation and conversion of methane to C.sub.2 + hydrocarbons in a reducing atmosphere, thereby avoiding formation of oxides of carbon.

  13. Microbiology: A microbial arsenic cycle in a salt-saturated, extreme environment

    USGS Publications Warehouse

    Oremland, R.S.; Kulp, T.R.; Blum, J.S.; Hoeft, S.E.; Baesman, S.; Miller, L.G.; Stolz, J.F.

    2005-01-01

    Searles Lake is a salt-saturated, alkaline brine unusually rich in the toxic element arsenic. Arsenic speciation changed from arsenate [As(V)] to arsenite [As(III)] with sediment depth. Incubated anoxic sediment slurries displayed dissimilatory As(V)-reductase activity that was markedly stimulated by H2 or sulfide, whereas aerobic slurries had rapid As(III)-oxidase activity. An anaerobic, extremely haloalkaliphilic bacterium was isolated from the sediment that grew via As(V) respiration, using either lactate or sulfide as its electron donor. Hence, a full biogeochemical cycle of arsenic occurs in Searles Lake, driven in part by inorganic electron donors.

  14. Crystallization of tholeiitic basalt in Alae Lava Lake, Hawaii

    USGS Publications Warehouse

    Peck, D.L.; Wright, T.L.; Moore, J.G.

    1966-01-01

    . Ferric-ferrous ratios suggest that oxidation with maximum intensity between 550??C and 610??C moved downward in the crust as it cooled; this was followed by reduction at a temperature of about 100??C. The crystallized basalt is a homogeneous fine-grained rock containing on the average 48.3 percent by volume intergranular pyroxene (augite > pigeonite), 34.2 percent plagioclase laths (An60 70), 7.9 percent interstitial glass, 6.9 percent opaques (ilmenite > magnetite), 2.7 percent olivine (Fo70 80), and a trace of apatite. Chemical analyses of 18 samples, ranging from initially quenched pumice to lava cored more than a year after the eruption from the center and from near the base of the lake, show little variation from silica-saturated tholeiitic basalt containing 50.4 percent SiO2, 2.4 percent Na2O, and 0.54 percent K2O. Apparently there was no significant crystal settling and no appreciable vapor-phase transport of these components during the year of crystallization. However, seven samples of interstitial liquid that had been filter-pressed into gash fractures and drill holes from partly crystalline mush near the base of the crust show large differences from the bulk composition of the solidified crust-lower MgO, CaO, and Al2O3; and higher total iron, TiO2, Na2O, K2O, P2O5, and F, and, in most samples, SiO2. The minor elements Ba, Ga, Li, Y, and Yb and possibly Cu tend to be enriched in the filter-pressed liquids, and Cr and possibly Ni tend to be depleted. ?? 1966 Stabilimento Tipografico Francesco Giannini & Figli.

  15. Biogenic Mn-Oxides in Subseafloor Basalts

    PubMed Central

    Ivarsson, Magnus; Broman, Curt; Gustafsson, Håkan; Holm, Nils G.

    2015-01-01

    The deep biosphere of the subseafloor basalts is recognized as a major scientific frontier in disciplines like biology, geology, and oceanography. Recently, the presence of fungi in these environments has involved a change of view regarding diversity and ecology. Here, we describe fossilized fungal communities in vugs in subseafloor basalts from a depth of 936.65 metres below seafloor at the Detroit Seamount, Pacific Ocean. These fungal communities are closely associated with botryoidal Mn oxides composed of todorokite. Analyses of the Mn oxides by Electron Paramagnetic Resonance spectroscopy (EPR) indicate a biogenic signature. We suggest, based on mineralogical, morphological and EPR data, a biological origin of the botryoidal Mn oxides. Our results show that fungi are involved in Mn cycling at great depths in the seafloor and we introduce EPR as a means to easily identify biogenic Mn oxides in these environments. PMID:26107948

  16. Lead isotope studies of mare basalt 70017

    NASA Technical Reports Server (NTRS)

    Mattinson, J. M.; Tilton, G. R.; Todt, W.; Chen, J. H.

    1977-01-01

    Uranium, thorium, and isotopic lead data for components of basalt 70017 are reported, and it is found that the whole rock, pyroxene, and ilmenite points in a concordia diagram plot along a chord intersecting the curve at 3.7 and 4.33 eons. The plagioclase data do not seem to lie on this line. The data for 70017 appear to plot along a distinctly different chord in a concordia diagram than do the data for 75055 and 75035, two other Apollo 17 mare basalts. The lead data are in accord with Sm-Nd results. A 3.7 eon crystallization age for 70017 would be consistent with the same kind of parentless lead that is indicated by previous studies of soils and soil breccias from stations at Taurus-Littrow. The Th/U ratio in ilmenite is 2.2, and the concentrations of these two elements are approximately twice those in pyroxene.

  17. Biogenic Mn-Oxides in Subseafloor Basalts.

    PubMed

    Ivarsson, Magnus; Broman, Curt; Gustafsson, Håkan; Holm, Nils G

    2015-01-01

    The deep biosphere of the subseafloor basalts is recognized as a major scientific frontier in disciplines like biology, geology, and oceanography. Recently, the presence of fungi in these environments has involved a change of view regarding diversity and ecology. Here, we describe fossilized fungal communities in vugs in subseafloor basalts from a depth of 936.65 metres below seafloor at the Detroit Seamount, Pacific Ocean. These fungal communities are closely associated with botryoidal Mn oxides composed of todorokite. Analyses of the Mn oxides by Electron Paramagnetic Resonance spectroscopy (EPR) indicate a biogenic signature. We suggest, based on mineralogical, morphological and EPR data, a biological origin of the botryoidal Mn oxides. Our results show that fungi are involved in Mn cycling at great depths in the seafloor and we introduce EPR as a means to easily identify biogenic Mn oxides in these environments. PMID:26107948

  18. Northwest Africa 5298: A Basaltic Shergottite

    NASA Technical Reports Server (NTRS)

    Hui, Hejiu; Peslier, Anne; Lapen, Thomas J.; Brandon, Alan; Shafer, John

    2009-01-01

    NWA 5298 is a single 445 g meteorite found near Bir Gandouz, Morocco in March 2008 [1]. This rock has a brown exterior weathered surface instead of a fusion crust and the interior is composed of green mineral grains with interstitial dark patches containing small vesicles and shock melts [1]. This meteorite is classified as a basaltic shergottite [2]. A petrologic study of this Martian meteorite is being carried out with electron microprobe analysis and soon trace element analyses by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Oxygen fugacity is calculated from Fe-Ti oxides pairs in the sample. The data from this study constrains the petrogenesis of basaltic shergottites.

  19. Total nitrogen content of deep sea basalts

    NASA Technical Reports Server (NTRS)

    Norris, T. L.; Schaeffer, O. A.

    1982-01-01

    An estimate of the total nitrogen content of the earth's mantle, aimed at furnishing a further constraint for earth atmosphere origin and evolution models, was attempted through thermal neutron activation analysis via N-14(n,p)C-14 for the case of deep sea basalt glasses from the East Pacific Rise, the Mid-Atlantic Rift, and the Juan de Fuca Ridge. The increased nitrogen abundance of matrix material from the same samples as the glasses may be due to the incorporation of chemically-bound nitrogen from sea water, rather than dissolved molecular nitrogen. A discussion is presented of factors affecting observed basalt nitrogen content and its interpretation in terms of mantle nitrogen abundance. A 2 ppm N lower limit is estimated for the mantle.

  20. Comparison of Lunar Basalts and Gabbros with those of the Terrestrial Ocean Crust

    NASA Astrophysics Data System (ADS)

    Natland, J. H.

    2012-12-01

    Initial studies of lunar samples returned from the Apollo and Luna missions took place before rocks of the Earth's lower ocean crust, chiefly varieties of gabbro cumulates, were widely known or understood. Continuing exploration of the ocean crust invites some new comparisons. When volcanic rocks and glass from Apollo 11 and 17 were discovered to have very high TiO2 contents (8-14%), nothing comparable was known from Earth. The high-TiO2 lunar samples were soon described as primary melts derived from considerable depths in the lunar mantle. Other lunar samples have only very low TiO2 contents (~0.2%) and very low concentrations of highly incompatible elements such as Zr and Sr. Today, dredging and drilling results indicate that oxide gabbros rich in magmatic oxides and sulfides and with up to 12% TiO2 comprise a significant percentage of the gabbroic portion of the ocean crust especially at slowly spreading ridges. These are very late stage differentiates, and are commonly juxtaposed by high-temperature deformation processes with more primitive olivine gabbros and troctolites having only ~0.2% TiO2 and low concentrations of Zr and other incompatible elements. The rocks are mainly adcumulates, with very low concentrations of incompatible elements set by proportions of cumulus minerals, and with little contribution from the liquids that produced them. In addition, some lunar gabbros with highly calcic plagioclase (~An93-98) are similar to gabbros and troctolites found in island arcs. All of these similarities suggest that very few lunar basaltic rocks are pristine; instead they all could be nearly complete shock fusion products produced by meteorite impact into a diverse assemblage of lunar gabbros that included both low- and high-TiO2 gabbroic facies. On this hypothesis, no lunar basalt is a primary melt derived from the Moon's mantle. Although magmatic environments on the ancient Moon and in the modern ocean crust were different in important ways, the general

  1. Uranium-lead isotope systematics of Mars inferred from the basaltic shergottite QUE 94201

    SciTech Connect

    Gaffney, A M; Borg, L E; Connelly, J N

    2006-12-22

    amount of sulfide crystallization may generate large extents of U-Pb fractionation during formation of the mantle sources of martian basalts.

  2. Nanoparticulate mineral matter from basalt dust wastes.

    PubMed

    Dalmora, Adilson C; Ramos, Claudete G; Querol, Xavier; Kautzmann, Rubens M; Oliveira, Marcos L S; Taffarel, Silvio R; Moreno, Teresa; Silva, Luis F O

    2016-02-01

    Ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been the subject of some concern recently around the world for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the mining district of Nova Prata in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3 and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition we have identified a number of trace metals such as Cd, Cu, Cr, Zn that are preferentially concentrated into the finer, inhalable, dust fraction and could so present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimise exposure to these natural fertilizing basalt dust wastes and is thus of direct relevance to both the industrial sector of basalt mining and to agriculture in the region.

  3. Nanoparticulate mineral matter from basalt dust wastes.

    PubMed

    Dalmora, Adilson C; Ramos, Claudete G; Querol, Xavier; Kautzmann, Rubens M; Oliveira, Marcos L S; Taffarel, Silvio R; Moreno, Teresa; Silva, Luis F O

    2016-02-01

    Ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been the subject of some concern recently around the world for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the mining district of Nova Prata in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3 and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition we have identified a number of trace metals such as Cd, Cu, Cr, Zn that are preferentially concentrated into the finer, inhalable, dust fraction and could so present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimise exposure to these natural fertilizing basalt dust wastes and is thus of direct relevance to both the industrial sector of basalt mining and to agriculture in the region. PMID:26551199

  4. Pb isotopic heterogeneity in basaltic phenocrysts

    SciTech Connect

    Bryce, Julia G.; DePaolo, Donald J.

    2002-06-01

    The Pb isotopic compositions of phenocrystic phases in young basaltic lavas have been investigated using the Getty-DePaolo method (Getty S. J. and DePaolo D. J. [1995] Quaternary geochronology by the U-Th-Pb method. Geochim. Cosmochim. Acta 59, 3267 3272), which allows for the resolution of small isotopic differences. Phenocryst, matrix, and whole rock analyses were made on samples from the 17 Myr-old Imnaha basalts of the Columbia River Group, a zero-age MORB from the Mid-Atlantic Ridge, and a ca. 260 kyr-old tholeiite from Mount Etna. Plagioclase feldspar phenocrysts have low-(U, Th)/Pb, and in each sample the plagioclase has significantly lower 206Pb/207Pb and 208Pb/207Pb values than whole rock, matrix, and magnetite-rich separates. The Pb isotopic contrast between plagioclase and matrix/whole rock is found in three samples with varying grain sizes (0.5 2 cm for the Imnaha basalt and MORB and <1 mm for the Etna sample) from different tectonic settings, suggesting that these results are not unique. The isotopic contrasts are only slightly smaller in magnitude than the variations exhibited by whole rock samples from the region. The Imnaha basalts also have Sr isotopic heterogeneity evident only in plagioclase phenocrysts, but the MORB and Etna lavas do not. The isotopic heterogeneities reflect magma mixing, and indicate that isotopically diverse magmas were mixed together just prior to eruption. The results reinforce indications from melt inclusion studies that magma source region isotopic heterogeneities have large amplitudes at short length scales, and that the isotopic variations imparted to the magmas are not entirely homogenized during segregation and transport processes.

  5. Hydrogen evolution from water through metal sulfide reactions

    SciTech Connect

    Saha, Arjun; Raghavachari, Krishnan

    2013-11-28

    Transition metal sulfides play an important catalytic role in many chemical reactions. In this work, we have conducted a careful computational study of the structures, electronic states, and reactivity of metal sulfide cluster anions M{sub 2}S{sub X}{sup −} (M = Mo and W, X = 4–6) using density functional theory. Detailed structural analysis shows that these metal sulfide anions have ground state isomers with two bridging sulfide bonds, notably different in some cases from the corresponding oxides with the same stoichiometry. The chemical reactivity of these metal sulfide anions with water has also been carried out. After a thorough search on the reactive potential energy surface, we propose several competitive, energetically favorable, reaction pathways that lead to the evolution of hydrogen. Selectivity in the initial water addition and subsequent hydrogen migration are found to be the key steps in all the proposed reaction channels. Initial adsorption of water is most favored involving a terminal metal sulfur bond in Mo{sub 2}S{sub 4}{sup −} isomers whereas the most preferred orientation for water addition involves a bridging metal sulfur bond in the case of W{sub 2}S{sub 4}{sup −} and M{sub 2}S{sub 5}{sup −} isomers. In all the lowest energy H{sub 2} elimination steps, the interacting hydrogen atoms involve a metal hydride and a metal hydroxide (or thiol) group. We have also observed a higher energy reaction channel where the interacting hydrogen atoms in the H{sub 2} elimination step involve a thiol (–SH) and a hydroxyl (–OH) group. For all the reaction pathways, the Mo sulfide reactions involve a higher barrier than the corresponding W analogues. We observe for both metals that reactions of M{sub 2}S{sub 4}{sup −} and M{sub 2}S{sub 5}{sup −} clusters with water to liberate H{sub 2} are exothermic and involve modest free energy barriers. However, the reaction of water with M{sub 2}S{sub 6}{sup −} is highly endothermic with a considerable

  6. How thick are lunar mare basalts

    NASA Technical Reports Server (NTRS)

    Hoerz, F.

    1978-01-01

    It is argued that De Hon's estimates of the thickness of lunar mare basalts, made by analyzing 'ghost' craters on mare surfaces, were inflated as the result of the crater morphometric data of Pike (1977) to reconstruct rim heights of degraded craters. Crater rim heights of 82 randomly selected highland craters of various states of degradation were determined, and median rim height was compared to that of corresponding fresh impact structures. Results indicate that the thickness estimates of De Hon may be reduced by a factor of 2, and that the total volume of mare basalt produced throughout lunar history could be as little as 1-2 million cubic kilometers. A survey of geochemical and petrographic evidence indicates that lateral transport of regolith components over distances of much greater than 10 km is relatively inefficient; it is suggested that vertical mixing of a highland substrate underlying the basaltic fill may have had a primordial role in generating the observed mare width distributions and high concentrations of exotic components in intrabasin regoliths.

  7. Voluminous granitic magmas from common basaltic sources

    USGS Publications Warehouse

    Sisson, T.W.; Ratajeski, K.; Hankins, W.B.; Glazner, A.F.

    2005-01-01

    Granitic-rhyolitic liquids were produced experimentally from moderately hydrous (1.7-2.3 wt% H2O) medium-to-high K basaltic compositions at 700 MPa and f O2 controlled from Ni-NiO -1.3 to +4. Amount and composition of evolved liquids and coexisting mineral assemblages vary with fO2 and temperature, with melt being more evolved at higher fO2s, where coexisting mineral assemblages are more plagioclase- and Fe-Ti oxide-rich and amphibole-poor. At fO2 of Ni-NiO +1, typical for many silicic magmas, the samples produce 12-25 wt% granitic-rhyolitic liquid, amounts varying with bulk composition. Medium-to-high K basalts are common in subduction-related magmatic arcs, and near-solidus true granite or rhyolite liquids can form widely, and in geologically significant quantities, by advanced crystallization-differentiation or by low-degree partial remelting of mantle-derived basaltic sources. Previously differentiated or weathered materials may be involved in generating specific felsic magmas, but are not required for such magmas to be voluminous or to have the K-rich granitic compositions typical of the upper continental crust. ?? Springer-Verlag 2005.

  8. Lunar sample studies. [breccias basalts, and anorthosites

    NASA Technical Reports Server (NTRS)

    1977-01-01

    Lunar samples discussed and the nature of their analyses are: (1) an Apollo 15 breccia which is thoroughly analyzed as to the nature of the mature regolith from which it derived and the time and nature of the lithification process, (2) two Apollo 11 and one Apollo 12 basalts analyzed in terms of chemistry, Cross-Iddings-Pirsson-Washington norms, mineralogy, and petrography, (3) eight Apollo 17 mare basalts, also analyzed in terms of chemistry, Cross-Iddings-Pirsson-Washington norms, mineralogy, and petrography. The first seven are shown to be chemically similar although of two main textural groups; the eighth is seen to be distinct in both chemistry and mineralogy, (4) a troctolitic clast from a Fra Mauro breccia, analyzed and contrasted with other high-temperature lunar mineral assemblages. Two basaltic clasts from the same breccia are shown to have affinities with rock 14053, and (5) the uranium-thorium-lead systematics of three Apollo 16 samples are determined; serious terrestrial-lead contamination of the first two samples is attributed to bandsaw cutting in the lunar curatorial facility.

  9. Evidence for hydrothermal Archaea within the basaltic flanks of the East Pacific Rise.

    PubMed

    Ehrhardt, Christopher J; Haymon, Rachel M; Lamontagne, Michael G; Holden, Patricia A

    2007-04-01

    Little is known about the fluids or the microbial communities present within potentially vast hydrothermal reservoirs contained in still-hot volcanic ocean crust beneath the flanks of the mid-ocean ridge. During Alvin dives in 2002, organic material attached to basalt was collected at low, near-ambient temperatures from an abyssal hill fault scarp in 0.5 Ma lithosphere on the western ridge flank of the East Pacific Rise. Mineral analysis by X-ray diffractometry and scanning electron microscopy revealed high-temperature (> 110 degrees C) phases chalcopyrite (Cu(5)FeS(4)) and 1C pyrrhotite (Fe(1-x)S) within the fault scarp materials. A molecular survey of archaeal genes encoding 16S rRNA identified a diverse hyperthermophilic community, including groups within Crenarchaeota, Euryarchaeota, and Korarchaeota. We propose that the sulfide, metals and archaeal communities originated within a basalt-hosted subseafloor hydrothermal habitat beneath the East Pacific Rise ridge flank and were transported to the seafloor during a recent episode of hydrothermal venting from the abyssal hill fault. Additionally, inferred metabolisms from the fault scarp community suggest that an ecologically unique high-temperature archaeal biosphere may thrive beneath the young East Pacific Rise ridge flank and that abyssal hill fault scarps may present new opportunities for sampling for this largely unexplored microbial habitat.

  10. Computed solid phases limiting the concentration of dissolved constituents in basalt aquifers of the Columbia Plateau in eastern Washington. Geochemical modeling and nuclide/rock/groundwater interaction studies

    SciTech Connect

    Deutsch, W.J.; Jenne, E.A.; Krupka, K.M.

    1982-08-01

    A speciation-solubility geochemical model, WATEQ2, was used to analyze geographically-diverse, ground-water samples from the aquifers of the Columbia Plateau basalts in eastern Washington. The ground-water samples compute to be at equilibrium with calcite, which provides both a solubility control for dissolved calcium and a pH buffer. Amorphic ferric hydroxide, Fe(OH)/sub 3/(A), is at saturation or modestly oversaturated in the few water samples with measured redox potentials. Most of the ground-water samples compute to be at equilibrium with amorphic silica (glass) and wairakite, a zeolite, and are saturated to oversaturated with respect to allophane, an amorphic aluminosilicate. The water samples are saturated to undersaturated with halloysite, a clay, and are variably oversaturated with regard to other secondary clay minerals. Equilibrium between the ground water and amorphic silica presumably results from the dissolution of the glassy matrix of the basalt. The oversaturation of the clay minerals other than halloysite indicates that their rate of formation lags the dissolution rate of the basaltic glass. The modeling results indicate that metastable amorphic solids limit the concentration of dissolved silicon and suggest the same possibility for aluminum and iron, and that the processes of dissolution of basaltic glass and formation of metastable secondary minerals are continuing even though the basalts are of Miocene age. The computed solubility relations are found to agree with the known assemblages of alteration minerals in the basalt fractures and vesicles. Because the chemical reactivity of the bedrock will influence the transport of solutes in ground water, the observed solubility equilibria are important factors with regard to chemical-retention processes associated with the possible migration of nuclear waste stored in the earth's crust.

  11. Identification of Mineral Phases on Basalt Surfaces by Imaging SIMS.

    PubMed

    Ingram, J C; Groenewold, G S; Olson, J E; Gianotto, A K; McCurry, M O

    1999-05-01

    A method for the identification of mineral phases on basalt surfaces utilizing secondary ion mass spectrometry (SIMS) with imaging capability is described. The goal of this work is to establish the use of imaging SIMS for characterization of the surface of basalt. The basalt surfaces were examined by interrogating the intact basalt (heterogeneous mix of mineral phases) as well as mineral phases that have been separated from the basalt samples. Mineral separates from the basalt were used to establish reference spectra for the specific mineral phases. Electron microprobe and X-ray photoelectron spectroscopy were used as supplemental techniques for providing additional characterization of the basalt. Mineral phases that make up the composition of the basalt were identified from single-ion images which were statistically grouped. The statistical grouping is performed by utilizing a program that employs a generalized learning vector quantization technique. Identification of the mineral phases on the basalt surface is achieved by comparing the mass spectra from the statistically grouped regions of the basalt to the mass spectral results from the mineral separates. The results of this work illustrate the potential for using imaging SIMS to study adsorption chemistry at the top surface of heterogeneous mineral samples.

  12. Partitioning of Se, As, Sb, Te and Bi between monosulfide solid solution and sulfide melt - Application to magmatic sulfide deposits

    NASA Astrophysics Data System (ADS)

    Helmy, Hassan M.; Ballhaus, Chris; Wohlgemuth-Ueberwasser, Cora; Fonseca, Raúl O. C.; Laurenz, Vera

    2010-11-01

    The chalcogenes (S, Se, Te), semimetals (As, Sb) and the metal Bi are important ligands for noble metals and form a wide range of compositionally diverse minerals with the platinum-group elements (PGE). With the exception of S, few experimental data exist to quantify the behavior of these elements in magmatic sulfide systems. Here we report experimental partition coefficients for Se, Te, As, Sb, and Bi between monosulfide solid solution (mss) and sulfide melt, determined at 950 °C at a range of sulfur fugacities ( fS2) bracketed by the Fe-FeS (metal-troilite) and the Fe 1-×S-S x (mss-sulfur) equilibria. Selenium is shown to partition in mss-saturated sulfide melt as an anion replacing S 2-. Arsenic changes its oxidation state with fS 2 from predominantly anionic speciation at low fS 2, to cationic speciation at high fS 2. The elements Sb, Te, and Bi are so highly incompatible with mss that they can only be present in sulfide melt as cations and/or as neutral metallic species. The partition coefficients derived fall with increasing atomic radius of the element. They also reflect the positions of the respective elements in the Periodic Table: within a group (e.g., As, Sb, Bi) the partition coefficients fall with increasing atomic radius, and within a period the elements of the 15th group are more incompatible with mss than the neighboring elements of the 16th group.

  13. Isotopic and REE studies of lunar basalt 12038 - Implications for petrogenesis of aluminous mare basalts

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Wooden, J. L.; Shih, C.-Y.; Wiesmann, H.; Bansal, B. M.

    1981-01-01

    Sr, Nd, and Sm isotopic studies of lunar basalt 12038, one of the so-called aluminous mare basalts, are reported. The evolution of the Sr and Nd isotopic compositions and the rare earth element (REE) abundances is successfully modeled within the framework of the model developed by Nyquist et al. (1977, 1979) for Apollo 12 olivine-pigeonite and ilmenite basalts. It is pointed out that the isotopic and trace element features of 12038 can by modeled as produced by partial melting of a cumulate mantle source which crystallized from a lunar magma ocean with a chondrite-normalized REE pattern of constant negative slope. Chondrite-normalized La/Yb is equal to 2.2 for this hypothetical magma ocean pattern.

  14. Making rhyolite in a basalt crucible

    NASA Astrophysics Data System (ADS)

    Eichelberger, John

    2016-04-01

    Iceland has long attracted the attention of those concerned with the origin of rhyolitic magmas and indeed of granitic continental crust, because it presents no alternative for such magmas other than deriving them from a basaltic source. Hydrothermally altered basalt has been identified as the progenitor. The fact that rhyolite erupts as pure liquid requires a process of melt-crustal separation that is highly efficient despite the high viscosity of rhyolite melt. Volcanoes in Iceland are foci of basaltic magma injection along the divergent plate boundary. Repeated injection produces remelting, digestion, and sometimes expulsion or lateral withdrawal of material resulting in a caldera, a "crucible" holding down-dropped and interlayered lava flows, tephras, and injected sills. Once melting of this charge begins, a great deal of heat is absorbed in the phase change. Just 1% change in crystallinity per degree gives a melt-present body an effective heat capacity >5 times the subsolidus case. Temperature is thus buffered at the solidus and melt composition at rhyolite. Basalt inputs are episodic ("fires") so likely the resulting generation of rhyolite by melting is too. If frequent enough to offset cooling between events, rhyolite melt extractions will accumulate as a rhyolite magma reservoir rather than as discrete crystallized sills. Evidently, such magma bodies can survive multiple firings without themselves erupting, as the 1875 eruption of Askja Caldera of 0.3 km3 of rhyolite equilibrated at 2-km depth without previous leakage over a ten-millennium period and the surprise discovery of rhyolite magma at 2-km depth in Krafla suggest. Water is required for melting; otherwise melting cannot begin at a temperature lower than that of the heat source. Because the solubility of water in melt is pressure-dependent and almost zero at surface pressure, there must be a minimum depth at which basalt-induced melting can occur and a rhyolite reservoir sustained. In practice, the

  15. Basaltic melt evolution of the Hengill volcanic system, SW Iceland, and evidence for clinopyroxene assimilation in primitive tholeiitic magmas

    SciTech Connect

    Troennes, R.G. )

    1990-09-10

    The thick oceanic crust of Iceland is formed by tholeiitic central volcanoes arranged in en echelon patterns along the 40-50 km wide rift zones. The Hengill central volcano in the southwestern rift zone has produced 25-30 km{sup 3} of hyaloclastites and lava during the last 0.11 m.y., with maximum productivity during the isostatic rebound following the degalciations 0.13 and 0.01 m.y. ago. The petrographic relations of pillow rim and hyaloclastite glass indicate that the basaltic melts were saturated with olivine and plagioclase, except for the most primitive ones that were undersaturated with plagioclase. Saturation with clinopyroxene was reached in some of the intermediate and evolved basaltic melts. Corroded and partly resorbed crystals of clinopyroxene and partly disintegrated gabbro nodules with resorbed clinopyroxene indicate that selective assimilation contributed to the evolution of the most primitive melts. The intermediate and evolved basaltic glass compositions fall along the low-pressure cotectic for mid-ocean ridge basalt (MORB) compositions saturated with olivine, plagioclase, and clinopyroxene, but the primitive glasses fall well inside the low-pressure olivine + plagioclase primary phase volume. The dense picritic magmas were driven to the surface by magmatic overpressure in the mantle at an early deglaciation stage characterized by the absence of large, trapping magma chambers in the lower crust. The assimilation of clinopyroxene in these melts could proceed by direct contact with the solidified cumulate sequences and gabbro intrusions. Clinopyroxene assimilation in combination with olivine fractionation may also contribute to the chemical evolution of some of the most primitive MORB magmas.

  16. Kinetics of sulfate reduction and sulfide precipitation rates in sediments of a bar-built estuary (Pescadero, California).

    PubMed

    Richards, Chandra M; Pallud, Céline

    2016-05-01

    The bar-built Pescadero Estuary in Northern California is a major fish rearing habitat, though recently threatened by near-annual fish kill events, which occur when the estuary transitions from closed to open state. The direct and indirect effects of hydrogen sulfide are suspected to play a role in these mortalities, but the spatial variability of hydrogen sulfide production and its link to fish kills remains poorly understood. Using flow-through reactors containing intact littoral sediment slices, we measured potential sulfate reduction rates, kinetic parameters of microbial sulfate reduction (Rmax, the maximum sulfate reduction rate, and Km, the half-saturation constant for sulfate), potential sulfide precipitation rates, and potential hydrogen sulfide export rates to water at four sites in the closed and open states. At all sites, the Michaelis-Menten kinetic rate equation adequately describes the utilization of sulfate by the complex resident microbial communities. We estimate that 94-96% of hydrogen sulfide produced through sulfate reduction precipitates in the sediment and that only 4-6% is exported to water, suggesting that elevated sulfide concentrations in water, which would affect fish through toxicity and oxygen consumption, cannot be responsible for fish deaths. However, the indirect effects of sulfide precipitates, which chemically deplete, contaminate, and acidify the water column during sediment re-suspension and re-oxidation in the transition from closed to open state, can be implicated in fish mortalities at Pescadero Estuary. PMID:26925545

  17. Geochemical controls on dissolved sodium in basalt aquifers of the Columbia Plateau, Washington

    USGS Publications Warehouse

    Hearn, P.P.; Steinkampf, W.C.; Bortleson, Gilbert C.; Drost, B.W.

    1985-01-01

    Miocene basaltic aquifers of the Columbia Plateau are the principal source of water for agricultural, domestic, and municipal use in Washington State. Irrigation with groundwaters with relatively high sodium concentrations has been cause for concern in recent years, because of the tendency of such waters to reduce soil permeability. Chemical reactions involving groundwater and the basalts are the primary mechanisms responsible for the input of sodium to groundwater in the plateau. This conclusion is supported by the sequence of secondary alteration products found and by progressive changes in groundwater chemistry with depth and position along regional flow paths. Upgradient and shallow groundwaters have low sodium concentrations and sodium-adsorption ratios (SAR's), and are predominantly calcium sodium bicarbonate waters. Groundwaters from deeper and downgradient locations have higher sodium concentrations and SAR 's and are predominantly sodium bicarbonate water. Volcanic glass and cryptocrystalline matrix are the major sources of groundwater sodium, and are dissolved by a combination of silicate hydrolysis and dissolution by carbonic acid. Magnesium, iron, and calcium are removed from solution by the formation of an iron magnesium smectite, calcite , and amorphous iron oxyhydroxide. The addition of sodium, silicon, and potassium by dissolution of basalt exceeds their removal by the precipitation of secondary minerals, and their concentrations increase in the initial stages of this process. In later stages, these continued increases produce a water saturated with clinoptilolite and silica phases, and these begin to precipitate. While the timing of these processes is unclear, the mineralogy of secondary alteration and estimated cooling rates of the basalt flows suggest that observed alteration products formed primarily at low temperature, under conditions similar to those existing at the present time. (USGS)

  18. Formation of orthopyroxenite by reaction between peridotite and hydrous basaltic melt: an experimental study

    NASA Astrophysics Data System (ADS)

    Wang, Chunguang; Liang, Yan; Dygert, Nick; Xu, Wenliang

    2016-09-01

    The consequences of hydrous basaltic melts and peridotite interaction were examined experimentally in Au-Pd, Pt, and graphite capsules using the reaction couple method. Reactions between a hydrous basaltic andesite (4 wt% H2O) and dunite or lherzolite in an Au-Pd capsule at 1 GPa and 1200 °C produce a melt-bearing orthopyroxenite-dunite sequence. Reactions between a hydrous ferro-basalt and lherzolite in Pt or Au-Pd capsules at 0.8-2 GPa and 1250-1385 °C produce a melt-bearing orthopyroxenite-harzburgite sequence. Reactions between the ferro-basalt and lherzolite in graphite capsules (not designed to retain water) result in a melt-bearing dunite-harzburgite sequence at 1 GPa and a melt-bearing harzburgite-lherzolite sequence at 2 GPa. The orthopyroxenite from the hydrous reaction experiments has a high porosity, and it is separated by a sharp lithological interface from the dunite or harzburgite. Orthopyroxenes in the orthopyroxenite are large in size with resorbed olivine inclusions. Formation of the high-porosity orthopyroxenite in the hydrous melt-rock reaction experiments is determined by the liquidus phase relation of the interface reacting melt and reaction kinetics. Reaction between orthopyroxene-saturated hydrous melt and olivine at melt-rock interface produces orthopyroxenite. Water infiltration induces hydrous melting of the lherzolite, producing a dunite or an orthopyroxene-depleted harzburgite. Efficient diffusive exchange between the partial melt and the hydrous reacting melt promotes orthopyroxene-oversaturation around the melt-rock interfacial region. The simplified experiments reveal end-member processes for understanding the formation of orthopyroxenite in the upper mantle. The presence of orthopyroxenites in mantle samples is a strong indication of hydrous melt and peridotite interaction.

  19. Marine diagenesis of hydrothermal sulfide

    SciTech Connect

    Moammar, M.O.

    1985-01-01

    An attempt is made to discuss the artificial and natural oxidation and hydrolysis of hydrothermal sulfide upon interaction with normal seawater. Synthetic and natural ferrosphalerite particles used in kinetic oxidation and hydrolysis studies in seawater develop dense, crystalline coatings consisting of ordered and ferrimagnetic delta-(Fe, Zn)OOH. Due to the formation of this reactive diffusion barrier, the release of Zn into solution decreases rapidly, and sulfide oxidation is reduced to a low rate determined by the diffusion of oxygen through the oxyhydroxide film. This also acts as an efficient solvent for ions such as Zn/sup 2 +/, Ca/sup 2 +/, and possibly Cd/sup 2 +/, which contribute to the stabilization of the delta-FeOOH structure. The oxidation of sulfide occurs in many seafloor spreading areas, such as 21/sup 0/N on the East Pacific Ridge. In these areas the old surface of the sulfide chimneys are found to be covered by an orange stain, and sediment near the base of nonactive vents is also found to consist of what has been referred to as amorphous iron oxide and hydroxide. This thesis also discusses the exceedingly low solubility of zinc in seawater, from delta-(Fe, Zn)OOH and the analogous phase (zinc-ferrihydroxide) and the zinc exchange minerals, 10-A manganate and montmorillonite. The concentrations of all four are of the same magnitude (16, 36.4, and 12 nM, respectively) as the zinc concentration in deep ocean water (approx. 10 nM), which suggests that manganates and montmorillonite with iron oxyhydroxides control zinc concentration in the deep ocean.

  20. Sulfide smelting using Ausmelt technology

    NASA Astrophysics Data System (ADS)

    Mounsey, Edward N.; Robilliard, Ken R.

    1994-08-01

    Over the past decade, Ausmelt has been developing the top submerged lancing process for the smelting of sulfidic ores to recover such metals as copper, lead, silver, tin, antimony, and nickel as well as for separation of minor elements such as arsenic, antimony, and bismuth. Development has taken place in Ausmelt's pilot plant in Dandenong, near Melbourne, Australia. A number of projects have proceeded to commercial-scale operation. This paper reviews developments at both the pilot and commercial scales.

  1. Hotspots, basalts, and the evolution of the mantle.

    PubMed

    Anderson, D L

    1981-07-01

    The trace element concentration patterns of continental and ocean island basalts and of mid-ocean ridge basalts are complementary. The relative sizes of the source regions for these fundamentally different basalt types can be estimated from the trace element enrichment-depletion patterns. Their combined volume occupies most of the mantle above the 670 kilometer discontinuity. The source regions separated as a result of early mantle differentiation and crystal fractionation from the resulting melt. The mid-ocean ridge basalts source evolved from an eclogite cumulate that lost its late-stage enriched fluids at various times to the shallower mantle and continental crust. The mid-ocean ridge basalts source is rich in garnet and clinopyroxene, whereas the continental and ocean island basalt source is a garnet peridotite that has experienced secondary enrichment. These relationships are consistent with the evolution of a terrestrial magma ocean. PMID:17741173

  2. Trace element composition of Luna 24 Crisium VLT basalt

    NASA Technical Reports Server (NTRS)

    Haskin, L. A.

    1978-01-01

    The origins of the individual particles analyzed from the Luna 24 core and the information they provide on the trace-element composition of Mare Crisium basalt are considered. Previous analyses of several Luna 24 soil fragments are reviewed. It is concluded that: (1) the average trace-element concentrations for 12 VLT basalt fragments are the best available estimates for bulk samples of Crisium VLT basalt; (2) there is weak evidence that the average Crisium basalt might have a small positive Eu anomaly relative to chondritic matter; (3) the soils contain components from sources other than the Crisium VLT basalt; and (4) there is no convincing information in concentrations of rare-earth elements, Co, Sc, FeO, or Na2O among the analyzed fragments to indicate more than one parent basalt.

  3. Hotspots, basalts, and the evolution of the mantle.

    PubMed

    Anderson, D L

    1981-07-01

    The trace element concentration patterns of continental and ocean island basalts and of mid-ocean ridge basalts are complementary. The relative sizes of the source regions for these fundamentally different basalt types can be estimated from the trace element enrichment-depletion patterns. Their combined volume occupies most of the mantle above the 670 kilometer discontinuity. The source regions separated as a result of early mantle differentiation and crystal fractionation from the resulting melt. The mid-ocean ridge basalts source evolved from an eclogite cumulate that lost its late-stage enriched fluids at various times to the shallower mantle and continental crust. The mid-ocean ridge basalts source is rich in garnet and clinopyroxene, whereas the continental and ocean island basalt source is a garnet peridotite that has experienced secondary enrichment. These relationships are consistent with the evolution of a terrestrial magma ocean.

  4. Metal sulfide for battery applications

    SciTech Connect

    Guidotti, R.A.

    1988-01-01

    A number of metal sulfides can be used in batteries as a cathode (reducible) material as part of an electrochemical couple to provide energy. There are a number of physical and chemical characteristics that can be evaluated for screening potential candidates for use in batteries. These include: cell potential vs. Li, thermal and chemical stability, electrical conductivity, allotropic form (phase), reaction kinetics during discharge, type of discharge mechanism, and material rechargeability. These are reviewed in general, with emphasis on sulfides of copper, iron, and molybdenum which are currently being used as cathodes in Li and Li-alloy batteries. The presence of impurities can adversely impact performance when naturally occurring sulfide minerals are used for battery applications. Sandia National Laboratories uses natural pyrite (FeS2) for its high-temperature, thermally activated Li(Si)/FeS2 batteries. The purification and processing procedures for the FeS2 involves both chemical and physical methods. Flotation was found to yield comparable results as HF leaching for removal of silica, but without the negative health and environmental concerns associated with this technique. 11 refs., 5 figs., 6 tabs.

  5. Chemical dissolution of sulfide minerals

    USGS Publications Warehouse

    Chao, T.T.; Sanzolone, R.F.

    1977-01-01

    Chemical dissolution treatments involving the use of aqua regia, 4 N HNO3, H2O2-ascorbic acid, oxalic acid, KClO3+HCl, and KClO3+HCl followed by 4 N HNO3 were applied to specimens of nine common sulfide minerals (galena, chalcopyrite, cinnabar, molybdenite, orpiment, pyrite, stibnite, sphalerite, and tetrahedrite) mixed individually with a clay loam soil. The resultant decrease in the total sulfur content of the mixture, as determined by using the Leco induction furnace, was used to evaluate the effectiveness of each chemical treatment. A combination of KClO3+HCl followed by 4 N HNO3 boiling gently for 20 min has been shown to be very effective in dissolving all the sulfide minerals. This treatment is recommended to dissolve metals residing in sulfide minerals admixed with secondary weathering products, as one step in a fractionation scheme whereby metals in soluble and adsorbed forms, and those associated with organic materials and secondary oxides, are first removed by other chemical extractants.

  6. Sulfide-Driven Microbial Electrosynthesis

    SciTech Connect

    Gong, YM; Ebrahim, A; Feist, AM; Embree, M; Zhang, T; Lovley, D; Zengler, K

    2013-01-01

    Microbial electrosynthesis, the conversion of carbon dioxide to organic molecules using electricity, has recently been demonstrated for acetogenic microorganisms, such as Sporomusa ovata. The energy for reduction of carbon dioxide originates from the hydrolysis of water on the anode, requiring a sufficiently low potential. Here we evaluate the use of sulfide as an electron source for microbial electrosynthesis. Abiotically oxidation of sulfide on the anode yields two electrons. The oxidation product, elemental sulfur, can be further oxidized to sulfate by Desulfobulbus propionicus, generating six additional electrons in the process. The eight electrons generated from the combined abiotic and biotic steps were used to reduce carbon dioxide to acetate on a graphite cathode by Sporomusa ovata at a rate of 24.8 mmol/day.m(2). Using a strain of Desulfuromonas as biocatalyst on the anode resulted in an acetate production rate of 49.9 mmol/day.m(2), with a Coulombic efficiency of over 90%. These results demonstrate that sulfide can serve effectively as an alternative electron donor for microbial electrosynthesis.

  7. Laboratory Shock Experiments on Basalt - Iron Sulfate Mixes at ~ 40 - 50 GPa and their Relevance to the Martian Reolith Component Present in Shergotties

    SciTech Connect

    Rao, M N; Nyquist, L E; Ross, D K; Asimow, P D; See, T; Sutton, S; Cardernas, F; Montes, R; Cintala, M

    2012-03-14

    Basaltic shergottites such as Shergotty, Zagami and EET79001 contain impact melt glass pockets that are rich in Martian atmospheric gases and are known as gas-rich impact-melt (GRIM) glasses. These glasses show evidence for the presence of a Martian regolith component based on Sm and Kr isotopic studies. The GRIM glasses are sometimes embedded with clusters of innumerable micron-sized iron-sulfide blebs associated with minor amounts of iron sulfate particles. These sulfide blebs are secondary in origin and are not related to the primary igneous sulfides occurring in Martian meteorites. The material comprising these glasses arises from the highly oxidizing Martian surface and sulfur is unlikely to occur as sulfide in the Martian regoilith. Instead, sulfur is shown to occur as sulfate based on APXS and Mossbauer results obtained by the Opportunity and Spirit rovers at Meridiani and Gusev. We have earlier suggested that the micron-sized iron sulfide globules in GRIM glasses were likely produced by shock-reduction of iron sulfate occurring in the regolith at the time when the GRIM glasses were produced by the meteoroid impact that launched the Martian meteorites into space. As a result of high energy deposition by shock (~ 40-60 GPa), the iron sulfate bearing phases are likely to melt along with other regolith components and will get reduced to immiscible sulfide fluid under reducing conditions. On quenching, this generates a dispersion of micron-scale sulfide blebs. The reducing agents in our case are likely to be H2 and CO which were shock-implanted from the Martian atmosphere into these glasses along with the noble gases. We conducted lab simulation experiments in the Lindhurst Laboratory of Experimental Geophysics at Caltech and the Experimental Impact Laboratory at JSC to test whether iron sulfide globules can be produced by impact-driven reduction of iron sulfate by subjecting Columbia River Basalt (CRB) and ferric sulfate mixtures to shock pressures

  8. Laboratory Shock Experiments on Basalt - Iron Sulfate Mixes at Approximately 40-50 GPa and Their Relevance to the Martian Regolith Component Present in Shergottites

    NASA Technical Reports Server (NTRS)

    Rao, M. N.; Nyquist, L. E.; Ross, D. K.; Asimow, P. D.; See, T.; Sutton, S.; Cardernas, F.; Montes, R.; Cintala, M.

    2012-01-01

    Basaltic shergottites such as Shergotty, Zagami and EET79001 contain impact melt glass pockets that are rich in Martian atmospheric gases [1] and are known as gas-rich impact-melt (GRIM) glasses. These glasses show evidence for the presence of a Martian regolith component based on Sm and Kr isotopic studies [2]. The GRIM glasses are sometimes embedded with clusters of innumerable micron-sized iron-sulfide blebs associated with minor amounts of iron sulfate particles [3, 4]. These sulfide blebs are secondary in origin and are not related to the primary igneous sulfides occurring in Martian meteorites. The material comprising these glasses arises from the highly oxidizing Martian surface and sulfur is unlikely to occur as sulfide in the Martian regoilith. Instead, sulfur is shown to occur as sulfate based on APXS and Mossbauer results obtained by the Opportunity and Spirit rovers at Meridiani and Gusev [5]. We have earlier suggested that the micron-sized iron sulfide globules in GRIM glasses were likely produced by shock-reduction of iron sulfate occurring in the regolith at the time when the GRIM glasses were produced by the meteoroid impact that launched the Martian meteorites into space [6]. As a result of high energy deposition by shock (approx. 40-60 GPa), the iron sulfate bearing phases are likely to melt along with other regolith components and will get reduced to immiscible sulfide fluid under reducing conditions. On quenching, this generates a dispersion of micron-scale sulfide blebs. The reducing agents in our case are likely to be H2 and CO which were shock-implanted from the Martian atmosphere into these glasses along with the noble gases. We conducted lab simulation experiments in the Lindhurst Laboratory of Experimental Geophysics at Caltech and the Experimental Impact Laboratory at JSC to test whether iron sulfide globules can be produced by impact-driven reduction of iron sulfate by subjecting Columbia River Basalt (CRB) and ferric sulfate mixtures to

  9. Vesicles, water, and sulfur in Reykjanes Ridge basalts

    USGS Publications Warehouse

    Moore, J.G.; Schilling, J.-G.

    1973-01-01

    Dredge hauls of fresh submarine basalt collected from the axis of the Reykjanes Ridge (Mid-Atlantic Ridge) south of Iceland were taken aboard R/ V TRIDENT in 1967 and 1971. The samples show systematic changes as the water depth of collection (and eruption) decreases: radially elongate vesicles and concentric zones of vesicles appear at about 700 m depth and are conspicuous to shallow water; the smoothed volume percent of vesicles increases from 5% at 1000 m, 10% at 700 m, to 16% at 500 m, and the scatter in degree of vesicularity increases in shallower water; specific gravity decreases from 2.7??0.1 at 1000 m to 2.3??0.3 at 100 m. Bulk sulfur content for the outer 2 cm averages 843 ppm up to a depth of 200 m, then drops off rapidly in shallower water owing to degassing. Sulfur content below 200 m is independent of depth (or geographic position), and the melt is apparently saturated with sulfur, but the excess cannot escape the lava unless another vehicle carries it out. Only shallower than 200 m, where intense vesiculation of other gases occurs can excess sulfur be lost from the lava erupting on the sea floor. H2O+110?? averages about 0.35 percent and H2O+150?? about 0.25 percent, and both apparently decrease in water shallower than 200 m as a result of degassing. H2O+ (below 200 m) decreases with distance from Iceland or increasing depth, presumably as a result of either adsorption of water on the surface of shallower, more vesicular rocks; or more likely due to the presence of the Iceland hot mantle plume supplying undifferentiated primordial material, relative to lavas of the Reykjanes Ridge supplied from the low velocity layer already depleted in volatiles and large lithophile elements. The H2O+110??/S ratio of lava erupting below 200 m water depth ranges from 3 to 5 which is comparable to reliable gas analyses from oceanic basaltic volcanoes. ?? 1973 Springer-Verlag.

  10. Se-Te fractionation by sulfide-silicate melt partitioning: Implications for the composition of mantle-derived magmas and their melting residues

    NASA Astrophysics Data System (ADS)

    Brenan, James M.

    2015-07-01

    Partitioning of Se and Te has been measured between coexisting sulfide liquid, monosulfide solid solution (MSS) and silicate melt at 0.9-1.5 GPa, 1200-1300 °C, fO2 controlled near the fayalite-magnetite-quartz buffer (FMQ-1.2 to -1.6) and 3-22 wt% FeO in the silicate melt. Both elements are highly compatible in the sulfide phase relative to silicate liquid (Dsulfide phase/silicate liquid > 600), with the identity of the sulfide dictating the sense of Se-Te fractionation. Whereas the measured DTe/DSe is ∼5-9 for sulfide liquid/silicate liquid partitioning, MSS/silicate melt partitioning fractionates Te from Se in the opposite sense, with DTe/DSe of ∼0.5-0.8. At fixed fO2, DSulLiq/SilLiq values for both Se and Te decrease ∼8-fold over the range in silicate melt FeO content investigated. The relative values of DSulLiq/SilLiq for Cu to Se increase with increasing FeO in the silicate melt, such that DCu exceeds DSe only for melts with >11 wt% FeO. Hence the standard belief that DCu >DSe as indicative of sulfide removal should be carefully assessed in the context of the FeO content of the magmas involved. Assuming a chondritic mantle Se/Te, predicted MSS and sulfide liquid compositions are generally in accord with natural mantle sulfides, in terms of their designation as MSS or sulfide liquid, based on independent criteria. However, additional variability is likely due to Te redistribution in accessory platinum group minerals (PGM), or that some sulfides are metasomatic. Calculations show that the Se/Te ratio of silicate melt derived from a sulfide liquid-saturated mantle is significantly higher, and more variable, than for silicate melt in equilibrium with residual MSS; modest sulfide liquid removal at low pressure, however, likely obscures the Se/Te fractionation imposed by the source sulfide phase. Models indicate that the composition of MORB is consistent with melts produced from sulfide-bearing sources with chondritic Se/Te, and source sulfur contents higher

  11. The mean composition of ocean ridge basalts

    NASA Astrophysics Data System (ADS)

    Gale, Allison; Dalton, Colleen A.; Langmuir, Charles H.; Su, Yongjun; Schilling, Jean-Guy

    2013-03-01

    mean composition of mid-ocean ridge basalts (MORB) is determined using a global data set of major elements, trace elements, and isotopes compiled from new and previously published data. A global catalog of 771 ridge segments, including their mean depth, length, and spreading rate enables calculation of average compositions for each segment. Segment averages allow weighting by segment length and spreading rate and reduce the bias introduced by uneven sampling. A bootstrapping statistical technique provides rigorous error estimates. Based on the characteristics of the data, we suggest a revised nomenclature for MORB. "ALL MORB" is the total composition of the crust apart from back-arc basins, N-MORB the most likely basalt composition encountered along the ridge >500 km from hot spots, and D-MORB the depleted end-member. ALL MORB and N-MORB are substantially more enriched than early estimates of normal ridge basalts. The mean composition of back-arc spreading centers requires higher extents of melting and greater concentrations of fluid-mobile elements, reflecting the influence of water on back-arc petrogenesis. The average data permit a re-evaluation of several problems of global geochemistry. The K/U ratio reported here (12,340 ± 840) is in accord with previous estimates, much lower than the estimate of Arevalo et al. (2009). The low Sm/Nd and 143Nd/144Nd ratio of ALL MORB and N-MORB provide constraints on the hypothesis that Earth has a non-chondritic primitive mantle. Either Earth is chondritic in Sm/Nd and the hypothesis is incorrect or MORB preferentially sample an enriched reservoir, requiring a large depleted reservoir in the deep mantle.

  12. Nontronite Mineralization in Columbia River Basalts

    NASA Astrophysics Data System (ADS)

    Baker, L.

    2015-12-01

    The ferric smectite nontronite is one of the first minerals formed by secondary weathering of Columbia River Basalts (CRB). Although nontronite is a common weathering product of CRB, it is not ubiquitous; field relations in near-surface flows suggest it only forms where sufficient water is available. In near-surface flows that are above the water table, nontronite is found filling cracks or vesicles, or in association with paleosols now preserved between flows in many localities. Field relations strongly suggest that porosity and permeability at the millimeter to meter scale control the supply of water for weathering and are key to the chemical composition of secondary clays and to the overall abundance of individual secondary weathering minerals. Weathering in the basalts initiates in void spaces that hold water, where high-Fe nontronite forms radiating acicular sprays. Small void spaces fill completely with nontronite of uniform composition, which penetrates the walls and replaces surrounding glass and ferromagnesian minerals. This process produces a relatively limited quantity of high-purity ferric nontronite. In large void spaces where water is limiting, nontronite lines the interior of vesicles but does not fill them; vermicular clay strands grow into the space from nucleation sites at the vesicle wall. Nontronitic cores are coated by layers of Mg- and Al-rich clays, and Mn oxides coat the exteriors. Thus, weathering under water-limited conditions appears to produce more compositionally complex mineral assemblages. In more extensively weathered basalts, nontronite is not present except in isolated, enclosed spaces. Results of this study may be useful in interpreting remotely sensed mineralogical data on Mars. The compositions of ferromagnesian smectites and spatial relationships between different clays on Mars may hold clues to the original conditions of water-rock interaction.

  13. Products of a Subglacial Flood Basalt Eruption

    NASA Astrophysics Data System (ADS)

    Gorny, C. F.; White, J. D. L.; Gudmundsson, M. T.

    2015-12-01

    The Snæbýlisheiði unit, SE Iceland, is a ca. 26 km³ elongate, flat-topped ridge of volcaniclastic debris coupled with and intruded by coherent basalt stretching over 34 km from the eruption site perpendicular to the rift fissure source. It formed from a single subglacial flood basalt eruption during a recent glaciation, and its elongation reflects glacial control on dispersal via the hydraulic potential gradient at the glacier's base, which drove towards the glacier terminus the meltwater+debris formed during the eruption by quenching and fragmentation. High magma discharge and outgassing drove segregation of magma into down-flow propagating intrusions. Edifice growth was mediated by the extent of ice melting, extent and efficiency of meltwater+debris drainage, and hydraulic gradients locally favoring meltwater accumulation. Eruption style reflected magma flux, edifice stability, and accessibility of water to the vent area via flooding or infiltration. Deposits reflect these competing factors in their chaotic internal organization and stratigraphy, limited lithofacies continuity, and diverse particle populations from multiple source vents. Linear growth of the ridge down-gradient from the eruption site was driven primarily by propagation and continuous fragmentation of shoaling intrusions that formed an interconnected intrusive complex with extensive peperites. Advance was along gently meandering and locally bifurcating sub-ice conduits within hyaloclastite with sheet-lobe levees and lobate fingered intrusions. Irregular dikes, apophyses, horns, and tendrils extended from the main body and generated voluminous lapilli tuff and contorticlasts while providing additional heat to the system. Prolonged transport and deposition of debris produced complexly bedded volcaniclastic deposits derived from and intruded by the basalt sheet. The bedding and depositional features of volcaniclastic debris and relationship to their adjacent intrusions suggest transport and

  14. Trace Element Diffusion in Basaltic Melt

    NASA Astrophysics Data System (ADS)

    Holycross, M.; Watson, E. B.

    2015-12-01

    We conducted high pressure, high temperature experiments to determine simultaneously the diffusivities of 24 trace elements (Sc, V, Rb, Y, Zr, Nb, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Hf, Ta, Th, U) in liquids of basaltic composition. Pre-synthesis runs were conducted in graphite capsules in a piston-cylinder apparatus to create two glasses having relatively high and low trace element contents. These glasses were then powdered and paired in diffusion couples by repacking in graphite capsules. All diffusion experiments were executed in a piston cylinder apparatus at 1 GPa pressure and temperatures ranging from 1250-1500º C. Concentration gradients that developed in the glasses were characterized using a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS). Diffusion coefficients were determined from concentration profiles and show Arrhenian behavior within experimental error. Errors were assigned based on the linear fit of five time series experiments conducted over 500-9000 s to accurately represent the total experimental reproducibility of our results. Data show the highest activation energies are obtained for high field strength elements. Values for the pre-exponential factor, D0, also peak for the high field strength elements. We suggest that trace element diffusion in basaltic melts follows the compensation law (Winchell, 1969), with log D0 exhibiting linear dependence on activation energy. Calculated diffusivities indicate that transport through basaltic melt could be an effective mechanism for fractionating high field strength elements over geologically relevant time scales. Winchell (1969) High Temp. Sci. 1: 200-215

  15. Hydrothermal Alteration in Submarine Basaltic Rocks from the Reykjanes Geothermal Field, Iceland. (Invited)

    NASA Astrophysics Data System (ADS)

    Zierenberg, R. A.; Schiffman, P.; Fowler, A. P.; Marks, N.; Fridleifsson, G.; Elders, W. A.

    2013-12-01

    The Iceland Deep Drilling Project (IDDP) is preparing to drill to 4-5 km in the Reykjanes Geothermal Field to sample geothermal fluids at supercritical temperature and pressure for power generation. The Reykjanes geothermal field is the on-land extension of the Reykjanes Ridge spreading center. The upper 1-2 kilometers drilled at Reykjanes are submarine basalts and basaltic sediments, hyalloclastites, and breccias, with an increasing proportion of basaltic intrusive rocks below 2 km depth. Geothermal fluids are evolved seawater with a composition similar to mid-ocean ridge hydrothermal systems. Zn- and Cu-rich sulfide scale, locally enriched in Au and Ag, are deposited in production pipes. The sulfide deposits are compositionally and isotopically similar to seafloor massive sulfides. In anticipation of deeper drilling, we have investigated the mineralogy and geochemistry of drill cuttings from a 3 km deep well (RN-17). The depth zoning of alteration minerals is similar to that described from other Icelandic geothermal fields, and is comparable to observed seafloor metamorphic gradients in ODP drill holes and ophiolites. Chlorite-epidote alteration occurs at depths >400 m and passes downhole through epidote-actinolite alteration and into amphibole facies (hornblende-calcic plagioclase) alteration below 2.5 km. Local zones of high temperature (>800°C), granoblastic-textured, pyroxene hornfels, are interpreted to form by contact metamorphism during dike/sill emplacement. Similar granoblasically altered basalts were recovered from the base of the sheeted dikes in IODP Hole 1256D. Downhole compositional variations of drill cuttings, collected every 50 m, suggest that rocks below ~ 2 km are little altered. Whole-rock oxygen isotope profiles are consistent with low water/rock ratios, but suggest that early stages of hydrothermal alteration included meteoric water-derived fluids. Strontium isotope profiles indicate more extensive exchange with seawater-derived fluids

  16. Mare basalt genesis - Modeling trace elements and isotopic ratios

    NASA Astrophysics Data System (ADS)

    Binder, A. B.

    1985-11-01

    Various types of mare basalt data have been synthesized, leading to the production of an internally consistent model of the mare basalt source region and mare basalt genesis. The model accounts for the mineralogical, major oxide, compatible siderophile trace element, incompatible trace element, and isotopic characteristics of most of the mare basalt units and of all the pyroclastic glass units for which reliable data are available. Initial tests of the model show that it also reproduces the mineralogy and incompatible trace element characteristics of the complementary highland anorthosite suite of rocks and, in a general way, those of the lunar granite suite of rocks.

  17. An estimate of the juvenile sulfur content of basalt

    USGS Publications Warehouse

    Moore, J.G.; Fabbi, Brent P.

    1971-01-01

    Sulfur analyses by X-ray fluorescence give an average content of 107 ppm for 9 samples of fresh subaerially-erupted oceanic basalt and 680 ppm for 38 samples of submarine erupted basalt. This difference is the result of retention of sulfur in basalt quenched on the sea floor and loss of sulfur in basalt by degassing at the surface. The outer glassy part of submarine erupted basalt contains 800??150 ppm sulfur, and this amount is regarded as an estimate of the juvenile sulfur content of the basalt melt from the mantle. The slower cooled interiors of basalt pillows are depleted relative to the rims owing to degassing and escape through surface fractures. Available samples of deep-sea basalts do not indicate a difference in original sulfur content between low-K tholeiite, Hawaiian tholeiite, and alkali basalt. The H2O/S ratio of analyzed volcanic gases is generally lower than the H2O/S ratio of gases presumed lost from surface lavas as determined by chemical differences between pillow rims and surface lavas. This enrichment of volcanic gases in sulfur relative to water may result from a greater degassing of sulfur relative to water from shallow intrusive bodies beneath the volcano. ?? 1971 Springer-Verlag.

  18. Quantifying glassy and crystalline basalt partitioning in the oceanic crust

    NASA Astrophysics Data System (ADS)

    Moore, Rachael; Ménez, Bénédicte

    2016-04-01

    The upper layers of the oceanic crust are predominately basaltic rock, some of which hosts microbial life. Current studies of microbial life within the ocean crust mainly focus on the sedimentary rock fraction, or those organisms found within glassy basalts while the potential habitability of crystalline basalts are poorly explored. Recently, there has been recognition that microbial life develops within fractures and grain boundaries of crystalline basalts, therefore estimations of total biomass within the oceanic crust may be largely under evaluated. A deeper understanding of the bulk composition and fractionation of rocks within the oceanic crust is required before more accurate estimations of biomass can be made. To augment our understanding of glassy and crystalline basalts within the oceanic crust we created two end-member models describing basalt fractionation: a pillow basalt with massive, or sheet, flows crust and a pillow basalt with sheeted dike crust. Using known measurements of massive flow thickness, dike thickness, chilled margin thickness, pillow lava size, and pillow lava glass thickness, we have calculated the percentage of glassy versus crystalline basalts within the oceanic crust for each model. These models aid our understanding of textural fractionation within the oceanic crust, and can be applied with bioenergetics models to better constrain deep biomass estimates.

  19. Study on basalt fiber parameters affecting fiber-reinforced mortar

    NASA Astrophysics Data System (ADS)

    Orlov, A. A.; Chernykh, T. N.; Sashina, A. V.; Bogusevich, D. V.

    2015-01-01

    This article considers the effect of different dosages and diameters of basalt fibers on tensile strength increase during bending of fiberboard-reinforced mortar samples. The optimal dosages of fiber, providing maximum strength in bending are revealed. The durability of basalt fiber in an environment of cement, by means of microscopic analysis of samples of fibers and fiberboard-reinforced mortar long-term tests is examined. The article also compares the behavior of basalt fiber in the cement stone environment to a glass one and reveals that the basalt fiber is not subject to destruction.

  20. Microbial colonization and alteration of basaltic glass

    NASA Astrophysics Data System (ADS)

    Einen, J.; Kruber, C.; Øvreås, L.; Thorseth, I. H.; Torsvik, T.

    2006-03-01

    Microorganisms have been reported to be associated with the alteration of the glassy margin of seafloor pillow basalts (Thorseth et al., 2001, 2003; Lysnes et al., 2004). The amount of iron and other biological important elements present in basalts and the vast abundance of basaltic glass in the earth's crust, make glass alteration an important process in global element cycling. To gain further insight into microbial communities associated with glass alteration, five microcosm experiments mimicking seafloor conditions were inoculated with seafloor basalt and incubated for one year. Mineral precipitations, microbial attachment to the glass and glass alteration were visualized by scanning electron microscopy (SEM), and the bacterial community composition was fingerprinted by PCR and denaturing gradient gel electrophoresis (DGGE) in combination with sequencing. SEM analysis revealed a microbial community with low morphological diversity of mainly biofilm associated and prosthecate microorganisms. Approximately 30 nm thick alteration rims developed on the glass in all microcosms after one year of incubation; this however was also seen in non inoculated controls. Calcium carbonate precipitates showed parallel, columnar and filamentous crystallization habits in the microcosms as well as in the sterile controls. DGGE analysis showed an alteration in bacterial community profiles in the five different microcosms, as a response to the different energy and redox regimes and time. In all microcosms a reduction in number of DGGE bands, in combination with an increase in cell abundance were recorded during the experiment. Sequence analysis showed that the microcosms were dominated by four groups of organisms with phylogenetic affiliation to four taxa: The Rhodospirillaceae, a family containing phototrophic marine organisms, in which some members are capable of heterotrophic growth in darkness and N2 fixation; the family Hyphomicrobiaceae, a group of prosthecate oligotrophic

  1. The nomenclature of polymict basaltic achondrites

    NASA Technical Reports Server (NTRS)

    Delaney, J. S.; Prinz, M.; Harlow, G. E.; Takeda, H.; Nehru, C. E.

    1983-01-01

    The system of nomenclature for basaltic achondrite meteorites is discussed, and new classification criteria are proposed. Under the new system, all achondrites are divided intno the broad groupings 'monomict' and 'polymict' by the number of lithologies present. The monomicts are classified structurally as brecciated or unbreccciated and as eucrites, diogenites, or cumulate eucrites. The polymicts are classified using an arbitrary mineral-chemical standard based on the percentage content of diogenite (magnesium orthopyroxenite): diogenites have more than 90 percent, eucrites have less than 10 percent, and all other polymicts area howardites. Tables listing all known achondrites by classification are provided.

  2. Plagioclase mineralogy of olivine alkaline basalt

    NASA Technical Reports Server (NTRS)

    Hoffer, J. M.

    1973-01-01

    A geological and mineralogical study of the Potrillo volcanics is reported. The investigation consisted first of field mapping to establish and identify the different rock types and volcanic features in order to determine the geological history. Next, samples were collected and analyzed petrographically to determine suitable rocks from the various stratigraphic units for study of plagioclase. Samples selected for further study were crushed and the plagioclase extracted for the determination of composition and structural state. These results were then related to the petrology and crystallization of the basalt.

  3. Thermal Infrared Spectra of Experimentally Shocked Basalt

    NASA Astrophysics Data System (ADS)

    Johnson, J. R.; Horz, F.

    2003-12-01

    We acquired thermal infrared (3-40 microns) emissivity and hemispherical reflectance spectra of experimentally shocked samples of a fine-grained basalt from Grand Falls, AZ to document the spectral effects of shock as a function of increasing shock pressures (17-57 GPa). This sample contains 25% pyroxene, 20% olivine, and 45% feldspar, making it a suitable analog to the Surface Type 1 (basalt) observed in Thermal Emission Spectrometer (TES) data of Mars. Reflectance data (3-14 microns) were acquired using a Nexus 470 FTIR spectrometer at the HIGP, University of Hawaii, and emission spectra (5-40 microns) were acquired using a Nicolet Nexus 670 emission spectrometer at Arizona State University. These data complement similar previous measurements of experimentally shocked plagioclase and pyroxene relevant to interpreting spectra provided by TES. The samples were shocked using the 25-mm barrel gun at Johnson Space Center and provided ~400 mg per sample. Large (2-10 mm) chips of recovered material were separated from the samples and washed to remove clinging fines, and the residual was powdered to provide a consistent grain size ( ˜20 microns). Spectra were obtained of both the chips and the powder samples. Results for the chips show a shift in band positions in the 900-1200 wavenumber (wn) region compared to unshocked samples, consistent with the structural degradation of feldspar and subsequent formation of maskelynite and glass. The development of a band near 460 wn at high pressures is also consistent with glass formation in feldspars. Conversely, absorptions related to pyroxene remain present even at high pressures, consistent with previous work. Results for the powders show little variations with increasing pressure except for the loss of minor transparency features in the 800-900 wn region. Additional visible/near-infrared (0.35-2.50 microns) measurements of the powdered basalt samples also will be acquired at the RELAB facility. Future work will include

  4. Vesiculation of basaltic magma during eruption

    USGS Publications Warehouse

    Mangan, M.T.; Cashman, K.V.; Newman, S.

    1993-01-01

    Vesicle size distributions in vent lavas from the Pu'u "O'o-Kupaianaha eruption of Kilauea volcano are used to estimate nucleation and growth rates of H2O-rich gas bubbles in basaltic magma nearing the earth's surface (???120 m depth). By using well-constrained estimates for the depth of volatile exsolution and magma ascent rate, nucleation rates of 35.9 events.cm-3.s-1 and growth rates of 3.2 ?? 10-4cm/s are determined directly from size-distribution data. The results are consistent with diffusion-controlled growth as predicted by a parabolic growth law. -from Authors

  5. 30 CFR 250.604 - Hydrogen sulfide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 2 2014-07-01 2014-07-01 false Hydrogen sulfide. 250.604 Section 250.604... § 250.604 Hydrogen sulfide. When a well-workover operation is conducted in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of H2S is unknown (as defined in § 250.490 of...

  6. 30 CFR 250.504 - Hydrogen sulfide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 2 2014-07-01 2014-07-01 false Hydrogen sulfide. 250.504 Section 250.504... § 250.504 Hydrogen sulfide. When a well-completion operation is conducted in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of H2S is unknown (as defined in § 250.490 of...

  7. 30 CFR 250.604 - Hydrogen sulfide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 2 2013-07-01 2013-07-01 false Hydrogen sulfide. 250.604 Section 250.604... § 250.604 Hydrogen sulfide. When a well-workover operation is conducted in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of H2S is unknown (as defined in § 250.490 of...

  8. 30 CFR 250.504 - Hydrogen sulfide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 2 2012-07-01 2012-07-01 false Hydrogen sulfide. 250.504 Section 250.504... § 250.504 Hydrogen sulfide. When a well-completion operation is conducted in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of H2S is unknown (as defined in § 250.490 of...

  9. 30 CFR 250.604 - Hydrogen sulfide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 2 2012-07-01 2012-07-01 false Hydrogen sulfide. 250.604 Section 250.604... § 250.604 Hydrogen sulfide. When a well-workover operation is conducted in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of H2S is unknown (as defined in § 250.490 of...

  10. 30 CFR 250.504 - Hydrogen sulfide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 2 2013-07-01 2013-07-01 false Hydrogen sulfide. 250.504 Section 250.504... § 250.504 Hydrogen sulfide. When a well-completion operation is conducted in zones known to contain hydrogen sulfide (H2S) or in zones where the presence of H2S is unknown (as defined in § 250.490 of...

  11. Petrogenesis of primitive and evolved basalts in a cooling Moon: Experimental constraints from the youngest known lunar magmas

    NASA Astrophysics Data System (ADS)

    Elardo, Stephen M.; Shearer, Charles K.; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Bell, Aaron S.

    2015-07-01

    We have conducted high-temperature experiments over a range of pressures to constrain the petrogenesis of the youngest sampled lunar magmas, which have contrasting primitive and evolved compositions. Our results indicate that at ∼3 Ga, melting still occurred within the same mantle depth range that produced crystalline mare basalts for the previous ∼1 Ga, although our data cannot support or confirm that the shallowest extents of melting moved deeper into the mantle by ∼3 Ga, as is predicted by most thermal evolution models. Furthermore, melting still occurred in regions with low abundances of heat-producing elements. Basaltic lunar meteorite NEA 003A has some of the lowest abundances of incompatible trace elements among all mare basalts and no negative Eu anomaly. Our experiments show that NEA 003A is multiply saturated with olivine and low-Ca pyroxene on its liquidus at ∼1.1 GPa (∼215 km) and ∼1330 °C. If the primitive NEA 003A liquid composition is a minimally-modified melt, the relatively low Mg# of its source region (73-75), its lack of a Eu anomaly, and its chondritic initial Nd isotopic composition indicate its source region likely escaped mixing during mantle overturn with later-stage magma ocean cumulates that formed after plagioclase saturation. This condition would require the sources of the ultramafic glasses to have experienced cumulate mixing, or for assimilation of later-stage magma ocean cumulates by the ultramafic glass parental magmas before eruption in order to account for their higher Mg#'s and deeper negative Eu anomalies. Alternatively, NEA 003A may have undergone some fractional crystallization, in which case its more primitive source region would be deeper than 215 km and may approach the depth range of the ultramafic glass source regions. Iron- and incompatible trace element-rich basaltic lunar meteorites LAP 02205, NWA 032/479, and NWA 4734 have nearly identical bulk compositions and have a multiple saturation point on their

  12. East Mariana Basin tholeiites: Cretaceous intraplate basalts or rift basalts related to the Ontong Java plume?

    USGS Publications Warehouse

    Castillo, P.R.; Pringle, M.S.; Carlson, R.W.

    1994-01-01

    Studies of seafloor magnetic anomaly patterns suggest the presence of Jurassic oceanic crust in a large area in the western Pacific that includes the East Mariana, Nauru and Pigafetta Basins. Sampling of the igneous crust in this area by the Deep Sea Drilling Program (DSDP) and the Ocean Drilling Program (ODP) allows direct evaluation of the age and petrogenesis of this crust. ODP Leg 129 drilled a 51 m sequence of basalt pillows and massive flows in the central East Mariana Basin. 40Ar 39Ar ages determined in this study for two Leg 129 basalts average 114.6 ?? 3.2 Ma. This age is in agreement with the Albian-late Aptian paleontologic age of the overlying sediments, but is distinctively younger than the Jurassic age predicted by magnetic anomaly patterns in the basin. Compositionally, the East Mariana Basin basalts are uniformly low-K tholeiites that are depleted in highly incompatible elements compared to moderately incompatible ones, which is typical of mid-ocean ridge basalts (MORB) erupted near hotspots. The Sr, Nd and Pb isotopic compositions of the tholeiites ( 87Sr 86Srinit = 0.70360-0.70374; 143Nd 144Ndinit = 0.512769-0.512790; 206Pb 204Pbmeas = 18.355-18.386) also overlap with some Indian Ocean Ridge MORB, although they are distinct from the isotopic compositions of Jurassic basalts drilled in the Pigafetta Basin, the oldest Pacific MORB. The isotopic compositions of the East Mariana Basin tholeiites are also similar to those of intraplate basalts, and in particular, to the isotopic signature of basalts from the nearby Ontong Java and Manihiki Plateaus. The East Mariana Basin tholeiites also share many petrologic and isotopic characteristics with the oceanic basement drilled in the Nauru Basin at DSDP Site 462. In addition, the new 110.8 ?? 1.0 Ma 40Ar 39Ar age for two flows from the bottom of Site 462 in the Nauru Basin is indistinguishable from the age of the East Mariana Basin flows. Thus, while magnetic anomaly patterns predict that the igneous

  13. Crystal Stratigraphy of Two Basalts from Apollo 16: Unique Crystallization of Picritic Basalt 606063,10-16 and Very-Low-Titanium Basalt 65703,9-13

    NASA Technical Reports Server (NTRS)

    Donohue, P. H.; Neal, C. R.; Stevens, R. E.; Zeigler, R. A.

    2014-01-01

    A geochemical survey of Apollo 16 regolith fragments found five basaltic samples from among hundreds of 2-4 mm regolith fragments of the Apollo 16 site. These included a high-Ti vitrophyric basalt (60603,10-16) and one very-low-titanium (VLT) crystalline basalt (65703,9-13). Apollo 16 was the only highlands sample return mission distant from the maria (approx. 200 km). Identification of basaltic samples at the site not from the ancient regolith breccia indicates input of material via lateral transport by post-basin impacts. The presence of basaltic rocklets and glass at the site is not unprecedented and is required to satisfy mass-balance constraints of regolith compositions. However, preliminary characterization of olivine and plagioclase crystal size distributions indicated the sample textures were distinct from other known mare basalts, and instead had affinities to impact melt textures. Impact melt textures can appear qualitatively similar to pristine basalts, and quantitative analysis is required to distinguish between the two in thin section. The crystal stratigraphy method is a powerful tool in studying of igneous systems, utilizing geochemical analyses across minerals and textural analyses of phases. In particular, trace element signatures can aid in determining the ultimate origin of these samples and variations document subtle changes occurring during their petrogenesis.

  14. Low-power-threshold photonic saturable absorber in nonlinear chalcogenide glass.

    PubMed

    Minardi, S; Cheng, G; D'Amico, C; Stoian, R

    2015-01-15

    We experimentally demonstrate controllable nonlinear modulation of optical guiding in ultrafast laser-written evanescently coupled waveguide arrays in bulk gallium lanthanum sulfide chalcogenide glass. The intensity-dependent response is validated by simulating light propagation in waveguide arrays with instantaneous Kerr nonlinearity using a discrete-continuous spatiotemporal unidirectional Maxwell equation model. The intensity-driven modulation of transmission in multicore structures acts as a potential saturable absorber at kilowatt threshold levels. PMID:25679858

  15. Saturation current spikes eliminated in saturable core transformers

    NASA Technical Reports Server (NTRS)

    Schwarz, F. C.

    1971-01-01

    Unsaturating composite magnetic core transformer, consisting of two separate parallel cores designed so impending core saturation causes signal generation, terminates high current spike in converter primary circuit. Simplified waveform, demonstrates transformer effectiveness in eliminating current spikes.

  16. Neuropsychologic effects of saturation diving.

    PubMed

    Vaernes, R J; Kløve, H; Ellertsen, B

    1989-05-01

    Neuropsychologic status of saturation divers was assessed before and after 300-500 msw dives (deep saturation diving--DSD group) and before and after 3.5 yr of ordinary saturation diving (saturation diving--SD group). Average baseline results showed the divers to be slightly superior to nondiving controls. Mild-to-moderate neuropsychologic changes (greater than 10% impairment) were found in measures of tremor, spatial memory, vigilance, and automatic reactivity in 20% of the divers after deep dives (DSD group). One year postdive no recovery was observed except for a vigilance test. In the SD group, 20% of the divers showed greater than 10% impairment after 3.5 yr of ordinary saturation diving. Significant reduction in autonomic reactivity was also found and there was a relationship between low autonomic reactivity before saturation diving and number of greater than 10% impairments. For the whole group (DSD + SD divers), negative correlations were found between saturation experience and results on memory and complex visuomotor tests. Years of diving from first to last examination was positively correlated with number of greater than 10% impairments and with reduction in autonomic reactivity. No similar correlations were found to dive variables after about 3 yr of air diving. The mild-to-moderate changes seen in some divers, therefore, seem to be the effects of saturation diving. Since one deep dive may cause an effect similar to the effect of 3.5 yr of ordinary saturation diving, there is reason to believe that repeated deep diving may lead to more pronounced neuropsychologic impairment.

  17. Basaltic caves at Craters of the Moon National Monument and Preserve as analogs for Mars

    NASA Astrophysics Data System (ADS)

    Hinman, N. W.; Richardson, C. D.; McHenry, L.; Scott, J. R.

    2010-12-01

    minerals were not included as no iron was detected in solution. Results compared well with evaporation of solutions generated by simulating chemical weathering of minerals found in the basalt; this approach allowed iron minerals to precipitate during evaporation because minerals in the basalt contained iron. The minerals modeled upon evaporation included the minerals observed in the actual deposits - hematite, calcite, and quartz. Na-minerals neared saturation in simulations but were normally not saturated, leaving open the question of their origin. One possible explanation for the presence of Na-minerals could be seasonal ice formation in the caves followed by sublimation, leaving more concentrated solutions behind than were sampled here. A seasonal model for mineral deposition in caves could be relevant to deposits in martian caves. While the formation mechanism for the secondary minerals at COM is not completely understood, the presence of secondary minerals that harbor organic compounds in a cave environment that may be analogous to Mar has implications for where to search for signs of martian life.

  18. Is Ishtar Terra a thickened basaltic crust?

    NASA Technical Reports Server (NTRS)

    Arkani-Hamed, Jafar

    1992-01-01

    The mountain belts of Ishtar Terra and the surrounding tesserae are interpreted as compressional regions. The gravity and surface topography of western Ishtar Terra suggest a thick crust of 60-110 km that results from crustal thickening through tectonic processes. Underthrusting was proposed for the regions along Danu Montes and Itzpapalotl Tessera. Crustal thickening was suggested for the entire Ishtar Terra. In this study, three lithospheric models with total thicknesses of 40.75 and 120 km and initial crustal thicknesses of 3.9 and 18 km are examined. These models could be produced by partial melting and chemical differentiation in the upper mantle of a colder, an Earth-like, and a hotter Venus having temperatures of respectively 1300 C, 1400 C, and 1500 C at the base of their thermal boundary layers associated with mantle convection. The effects of basalt-granulite-eclogite transformation (BGET) on the surface topography of a thickening basaltic crust is investigated adopting the experimental phase diagram and density variations through the phase transformation.

  19. Degassing of reduced carbon from planetary basalts

    PubMed Central

    Wetzel, Diane T.; Rutherford, Malcolm J.; Jacobsen, Steven D.; Hauri, Erik H.; Saal, Alberto E.

    2013-01-01

    Degassing of planetary interiors through surface volcanism plays an important role in the evolution of planetary bodies and atmospheres. On Earth, carbon dioxide and water are the primary volatile species in magmas. However, little is known about the speciation and degassing of carbon in magmas formed on other planets (i.e., Moon, Mars, Mercury), where the mantle oxidation state [oxygen fugacity (fO2)] is different from that of the Earth. Using experiments on a lunar basalt composition, we confirm that carbon dissolves as carbonate at an fO2 higher than -0.55 relative to the iron wustite oxygen buffer (IW-0.55), whereas at a lower fO2, we discover that carbon is present mainly as iron pentacarbonyl and in smaller amounts as methane in the melt. The transition of carbon speciation in mantle-derived melts at fO2 less than IW-0.55 is associated with a decrease in carbon solubility by a factor of 2. Thus, the fO2 controls carbon speciation and solubility in mantle-derived melts even more than previous data indicate, and the degassing of reduced carbon from Fe-rich basalts on planetary bodies would produce methane-bearing, CO-rich early atmospheres with a strong greenhouse potential. PMID:23569260

  20. Identifying recycled ash in basaltic eruptions

    NASA Astrophysics Data System (ADS)

    D'Oriano, Claudia; Bertagnini, Antonella; Cioni, Raffaello; Pompilio, Massimo

    2014-07-01

    Deposits of mid-intensity basaltic explosive eruptions are characterized by the coexistence of different types of juvenile clasts, which show a large variability of external properties and texture, reflecting alternatively the effects of primary processes related to magma storage or ascent, or of syn-eruptive modifications occurred during or immediately after their ejection. If fragments fall back within the crater area before being re-ejected during the ensuing activity, they are subject to thermally- and chemically-induced alterations. These `recycled' clasts can be considered as cognate lithic for the eruption/explosion they derive. Their exact identification has consequences for a correct interpretation of eruption dynamics, with important implications for hazard assessment. On ash erupted during selected basaltic eruptions (at Stromboli, Etna, Vesuvius, Gaua-Vanuatu), we have identified a set of characteristics that can be associated with the occurrence of intra-crater recycling processes, based also on the comparison with results of reheating experiments performed on primary juvenile material, at variable temperature and under different redox conditions.

  1. Emplacement of Columbia River flood basalt

    SciTech Connect

    Reidel, Stephen P. )

    1997-11-01

    Evidence is examined for the emplacement of the Umatilla, Wilbur Creek, and the Asotin Members of Columbia River Basalt Group. These flows erupted in the eastern part of the Columbia Plateau during the waning phases of volcanism. The Umatilla Member consists of two flows in the Lewiston basin area and southwestern Columbia Plateau. These flows mixed to form one flow in the central Columbia Plateau. The composition of the younger flow is preserved in the center and the composition of the older flow is at the top and bottom. There is a complete gradation between the two. Flows of the Wilbur Creek and Asotin Members erupted individually in the eastern Columbia Plateau and also mixed together in the central Columbia Plateau. Comparison of the emplacement patterns to intraflow structures and textures of the flows suggests that very little time elapsed between eruptions. In addition, the amount of crust that formed on the earlier flows prior to mixing also suggests rapid emplacement. Calculations of volumetric flow rates through constrictions in channels suggest emplacement times of weeks to months under fast laminar flow for all three members. A new model for the emplacement of Columbia River Basalt Group flows is proposed that suggests rapid eruption and emplacement for the main part of the flow and slower emplacement along the margins as the of the flow margin expands.

  2. Hafnium isotope variations in oceanic basalts.

    USGS Publications Warehouse

    Patchett, P.J.; Tatsumoto, M.

    1980-01-01

    Routine low-blank chemistry and 0.01-0.04% precision on the ratio 176Hf/177Hf allows study of Hf isotopic variations, generated by beta --decay of 176Lu, in volcanic rocks derived from the suboceanic mantle. Normalized to 176Hf/177Hf = 0.7325, 176Hf/177Hf ranges 0.2828-0.2835, based on 24 basalt samples. 176Hf/177Hf is positively correlated with 143Nd/144Nd, and negatively correlated with 87Sr/86Sr and 206Pb/204Pb. Along the Iceland-Reykjanes ridge traverse, 176Hf/177Hf increases southwards. The coherence of Hf, Nd and Sr isotopes in the oceanic mantle allows an approximate bulk Earth 176Hf/177Hf of 0.28295 to be inferred from the bulk Earth 143Nd/144Nd. This requires the bulk Earth Lu/Hf to be 0.25, similar to that of the Juvinas eucrite. 60% of the Hf isotopic variation in oceanic basalts occurs among mid-ocean ridge samples. Lu-Hf fractionation probably decouples from Sm-Nd and Rb-Sr fractionation in very depleted source regions, with high Lu/Hf, and consequent high 176Hf/177Hf ratios developing in mantle residual from partial melting. (Authors' abstract) -T.R.

  3. Identifying recycled ash in basaltic eruptions.

    PubMed

    D'Oriano, Claudia; Bertagnini, Antonella; Cioni, Raffaello; Pompilio, Massimo

    2014-07-28

    Deposits of mid-intensity basaltic explosive eruptions are characterized by the coexistence of different types of juvenile clasts, which show a large variability of external properties and texture, reflecting alternatively the effects of primary processes related to magma storage or ascent, or of syn-eruptive modifications occurred during or immediately after their ejection. If fragments fall back within the crater area before being re-ejected during the ensuing activity, they are subject to thermally- and chemically-induced alterations. These 'recycled' clasts can be considered as cognate lithic for the eruption/explosion they derive. Their exact identification has consequences for a correct interpretation of eruption dynamics, with important implications for hazard assessment. On ash erupted during selected basaltic eruptions (at Stromboli, Etna, Vesuvius, Gaua-Vanuatu), we have identified a set of characteristics that can be associated with the occurrence of intra-crater recycling processes, based also on the comparison with results of reheating experiments performed on primary juvenile material, at variable temperature and under different redox conditions.

  4. Degassing of reduced carbon from planetary basalts.

    PubMed

    Wetzel, Diane T; Rutherford, Malcolm J; Jacobsen, Steven D; Hauri, Erik H; Saal, Alberto E

    2013-05-14

    Degassing of planetary interiors through surface volcanism plays an important role in the evolution of planetary bodies and atmospheres. On Earth, carbon dioxide and water are the primary volatile species in magmas. However, little is known about the speciation and degassing of carbon in magmas formed on other planets (i.e., Moon, Mars, Mercury), where the mantle oxidation state [oxygen fugacity (fO2)] is different from that of the Earth. Using experiments on a lunar basalt composition, we confirm that carbon dissolves as carbonate at an fO2 higher than -0.55 relative to the iron wustite oxygen buffer (IW-0.55), whereas at a lower fO2, we discover that carbon is present mainly as iron pentacarbonyl and in smaller amounts as methane in the melt. The transition of carbon speciation in mantle-derived melts at fO2 less than IW-0.55 is associated with a decrease in carbon solubility by a factor of 2. Thus, the fO2 controls carbon speciation and solubility in mantle-derived melts even more than previous data indicate, and the degassing of reduced carbon from Fe-rich basalts on planetary bodies would produce methane-bearing, CO-rich early atmospheres with a strong greenhouse potential. PMID:23569260

  5. Growth of large sulfide structures on the endeavour segment of the Juan de Fuca ridge

    NASA Astrophysics Data System (ADS)

    Tivey, Margaret K.; Delaney, John R.

    1986-04-01

    Mapping and sampling with DSRV "Alvin" has established that sulfide blocks 0.5 m across, dredged from the axial valley of the Endeavour Segment at 47°57'N, are samples of unusually large sulfide structures. The steep-sided structures, up to 30 m in length, 20 m in height, and 10-15 m across, are localized by venting along normal faults at the base of the western axial valley wall, and are distributed for about 200 m along strike paralleling the 020 trend of the ridge crest. High-temperature fluids (350 to more than 400°C) pass through the massive sulfide structures and enter seawater through small, concentric "nozzle-like" features projecting from the top or the sides of the larger vent structures. Diffuse, low-temperature flow is pervasive in the vicinity of the active sulfide structures, exiting from basalt and sulfide surfaces alike. Evidence of recent volcanic activity is sparse. The two largest samples taken with the dredge would not have been recoverable using the submersible. These samples represent massive, complex portions of the sulfide structures which were not closely associated with rapid high-temperature fluid flow at the time of sampling; they contain textural evidence of sealed hydrothermal fluid exit channels. Mineralogy is dominated by Fe sulfides nnd amorphous silica. Pyrite, marcasite, wurtzite, chalcopyrite, and iss are the most common sulfide phases. Pyrrhotite, galena, and sphalerite are present in trace amounts. Barite, amorphous silica, and chalcedony are the only non-sulfide phases; anhydrite is not observed in any of the dredge samples, although it is common in the chimney-like samples recovered by "Alvin". Specific mineralogical-textural zones within the dredge samples are anaoogous to individual layers in East Pacific Rise at 21°N and southern Juan de Fuca Ridge samples, with two exceptions: a coarse-grained, highly porous Fe sulfide-rich interior containing sulfidized tubeworm casts, and a 2-5 cm thick zone near the outer margin of

  6. The geochemical characteristics of basaltic and acidic volcanics around the Myojin depression in the Izu arc, Japan

    NASA Astrophysics Data System (ADS)

    Haraguchi, S.; Tamaki, K.; Kato, Y.; Machida, S.

    2012-12-01

    Around the Myojin Depression, westside of the Myojin-sho caldera in the Izu arc, seamounts are circular distributed and hydrothermal activity with sulfide deposition are found from the Baiyonneise Caldera, one of seamounts at the northern side. Some knoll chains distribute in the eastside of the Myojin Depression, and connect between these knolls. This circulator distribution of seamounts and connected knoll chains considered to the dykes are similar to the geographical features of the Kuroko Depositions in the Hokuroku Region, Northwest Japan (Tanahashi et al., 2008). Hydrothermal activities are also found from the other rifts (Urabe and Kusakabe 1990). Based on these observations, the cruise KT09-12 by R/V Tansei-Maru, Ocean Research Institute (ORI), University of Tokyo, investigated in the Myojin Rift. During the cruise, basaltic to dacitic volcanic rocks and some acidic plutonic rocks were recovered by dredge system. Herein, we present petrographical and chemical analyses of these rock samples with sample dredged by the cruise MW9507 by R/V MOANA WAVE, and consider the association with hydrothermal activities and depositions. Dredges during the cruise KT09-12 were obtained at the Daini-Beiyonneise Knoll at the northern side, Daisan-Beiyonneise Knoll at the southern side, and the Dragonborn Hill, small knoll chains, at the southeastern side of the depression. Many volcanic rocks are basalt, and recovered mainly from the Dragonborn Hill. Andesite and dacite was recovered from the Daini- and the Daini-Bayonneise Knoll. Tonalites were recovered from the Daisan-Bayonneise Knoll. Basalts from the Dragonborn Hill show less than 50% of SiO2 and more than 6 wt% and 0.88 wt% of MgO and TiO2 content. Basalts from the rift zone show depleted in the volcanic front (VF) side and enriched in the reararc (RA) side. The Dragonborn Hill is distributed near the VF, and basalts show depleted geochemical characteristics. However, these characteristics are different from the basalts

  7. Density of basalt core from Hilo drill hole, Hawaii

    USGS Publications Warehouse

    Moore, J.G.

    2001-01-01

    Density measurements of 1600 samples of core from 889 to 3097 m depth below sea level in the Hawaii Scientific Drilling Program hole near Hilo, Hawaii show marked differences between the basaltic rock types and help define stratigraphy in the hole. Water-saturated densities of subaerial lava flows (occurring above 1079 m depth) have the broadest range because of the large density variation within a single lava flow. Water-saturated densities commonly range from 2.0 to 3.0 with an average of 2.55 ?? 0.24 g/cc. Dikes and sills range from 2.8 to 3.1 g/cc). Densities of hyaloclastite commonly range from 2.3 to 2.7, with an overall average of about 2.5 g/cc. The low-density of most hyaloclastite is due primarily to palagonitization of abundant glass and presence of secondary minerals in the interstices between fragments. Four principal zones of pillow lava, separated by hyaloclastite, occur in the drill core. The shallowest (1983-2136 m) is paradoxically the densest, averaging 3.01 ?? 0.10 g/cc. The second (2234-2470 m) is decidedly the lightest, averaging 2.67 ?? 0.13 g/cc. The third (2640-2790 m) and fourth (2918-bottom at 3097 m) are high, averaging 2.89 ?? 0.17 and 2.97 ?? 0.08 g/cc, respectively. The first pillow zone includes degassed pillows i.e. lava erupted on land that flowed into the sea. These pillows are poor in vesicles, because the subaerial, one-atmosphere vesicles were compressed when the flow descended to deeper water and higher pressure. The second (low-density, non-degassed) pillow zone is the most vesicle-rich, apparently because it was erupted subaqueously at a shallow depth. The higher densities of the third and fourth zones result from a low vesicularity of only a few percent and an olivine content averaging more than 5% for the third zone and about 10% for the fourth zone. The uppermost hyaloclastite extending about 400 m below the bottom of the subaerial basalt is poorly cemented and absorbs up to 6 wt% of water when immersed. Progressing

  8. Petrogenesis and ore genesis of the Permian Huangshanxi sulfide ore-bearing mafic-ultramafic intrusion in the Central Asian Orogenic Belt, western China

    NASA Astrophysics Data System (ADS)

    Mao, Ya-Jing; Qin, Ke-Zhang; Li, Chusi; Xue, Sheng-Chao; Ripley, Edward M.

    2014-07-01

    The Permian Huangshanxi mafic-ultramafic intrusion hosts one of the two largest magmatic sulfide deposits in the Eastern Tianshan which is situated in the southern margin of the Central Asian Orogenic Belt. In this paper we use mineral compositions and whole-rock geochemical data to decipher the genetic relationship between magma evolution and sulfide mineralization. The Huangshanxi intrusion consists of three separate intrusive units. Important sulfide mineralization occurs in the base of the last intrusive unit, an elongated, layered ultramafic body composed of lherzolite at the bottom, olivine websterite in the middle and websterite at the top. Based on olivine-liquid equilibria and mass balance, the MgO and FeO contents in the parental magma for a lherzolite sample are estimated to be 8.71 and 8.36 wt.%, respectively. The Huangshanxi mafic-ultramafic intrusive rocks and the estimated "trapped liquids" for several olivine-orthopyroxene cumulate rocks all show light rare earth element enrichments relative to heavy rare earth elements and significant Nb depletions relative to Th and La, which are similar to the characteristics of coeval basalts in the region. The arc-like geochemical features are attributed to pre-Permian mantle metasomatism by slab-derived fluids. Partial melting of the previously-modified mantle is thought to have resulted from heating by upwelling asthenosphere associated with post-subduction lithosphere delamination or by mantle plume activity. The relationship between the Fo and Ni contents of olivine crystals from the Huangshanxi sulfide-poor ultramafic rocks (< 1 wt.% S) indicates cotectic sulfide segregation during olivine crystallization. Significant depletions in platinum group elements (PGE) relative to Ni and Cu in the bulk sulfide ores of the Huangshanxi deposit are likely due to sulfide retention in the source mantle. Stratigraphic reversals in olivine Fo contents and bulk sulfide PGE tenors suggest that multiple magma replenishments

  9. Lithium-cupric sulfide cell

    SciTech Connect

    Cuesta, A.J.; Bump, D.D.

    1980-01-01

    Lithium cells have become the primary power source for cardiac pacemakers due to their reliability and longevity at low current drain rates. A lithium-cupric sulfide cell was developed which makes maximum use of the shape of a pacemaker's battery compartment. The cell has a stable voltage throughout 90% of its lifetime. It then drops to a second stable voltage before depletion. The voltage drop creates a small decrease in pacemaker rate, which alerts the physician to replace the pacemaker. No loss of capacity due to self-discharge as been seen to date, and cells have proven to be safe under extreme conditions. 2 refs.

  10. Molybdenum sulfide/carbide catalysts

    DOEpatents

    Alonso, Gabriel; Chianelli, Russell R.; Fuentes, Sergio; Torres, Brenda

    2007-05-29

    The present invention provides methods of synthesizing molybdenum disulfide (MoS.sub.2) and carbon-containing molybdenum disulfide (MoS.sub.2-xC.sub.x) catalysts that exhibit improved catalytic activity for hydrotreating reactions involving hydrodesulfurization, hydrodenitrogenation, and hydrogenation. The present invention also concerns the resulting catalysts. Furthermore, the invention concerns the promotion of these catalysts with Co, Ni, Fe, and/or Ru sulfides to create catalysts with greater activity, for hydrotreating reactions, than conventional catalysts such as cobalt molybdate on alumina support.

  11. Preparation of amorphous sulfide sieves

    DOEpatents

    Siadati, Mohammad H.; Alonso, Gabriel; Chianelli, Russell R.

    2006-11-07

    The present invention involves methods and compositions for synthesizing catalysts/porous materials. In some embodiments, the resulting materials are amorphous sulfide sieves that can be mass-produced for a variety of uses. In some embodiments, methods of the invention concern any suitable precursor (such as thiomolybdate salt) that is exposed to a high pressure pre-compaction, if need be. For instance, in some cases the final bulk shape (but highly porous) may be same as the original bulk shape. The compacted/uncompacted precursor is then subjected to an open-flow hot isostatic pressing, which causes the precursor to decompose and convert to a highly porous material/catalyst.

  12. Does crater 'saturation equilibrium' occur in the solar system?

    NASA Technical Reports Server (NTRS)

    Hartmann, W. K.

    1984-01-01

    The similarity in crater densities on the most heavily cratered surfaces throughout the solar system is statistically examined and discussed in terms of a 'saturation equilibrium' being achieved by cratering processes. This hypothesis accounts for (1) the similarity in maximum relative crater density, below certain theoretically predicted values, on all heavily cratered surfaces; (2) a levelling off at this same relative density among 100-m scale craters in populations on lunar maria and other sparsely cratered lunar surfaces; and (3) the approximate uniformity of maximum relative densities on Saturn satellites. The lunar frontside upland crater population, sometimes described as a well-preserved production function useful for interpreting other planetary surfaces, is found not to be a production function. It was modified by intercrater plains at least partly formed by early upland basaltic lava flooding.

  13. Landsliding in partially saturated materials

    NASA Astrophysics Data System (ADS)

    Godt, Jonathan W.; Baum, Rex L.; Lu, Ning

    2009-01-01

    Rainfall-induced landslides are pervasive in hillslope environments around the world and among the most costly and deadly natural hazards. However, capturing their occurrence with scientific instrumentation in a natural setting is extremely rare. The prevailing thinking on landslide initiation, particularly for those landslides that occur under intense precipitation, is that the failure surface is saturated and has positive pore-water pressures acting on it. Most analytic methods used for landslide hazard assessment are based on the above perception and assume that the failure surface is located beneath a water table. By monitoring the pore water and soil suction response to rainfall, we observed shallow landslide occurrence under partially saturated conditions for the first time in a natural setting. We show that the partially saturated shallow landslide at this site is predictable using measured soil suction and water content and a novel unified effective stress concept for partially saturated earth materials.

  14. Landsliding in partially saturated materials

    USGS Publications Warehouse

    Godt, J.W.; Baum, R.L.; Lu, N.

    2009-01-01

    [1] Rainfall-induced landslides are pervasive in hillslope environments around the world and among the most costly and deadly natural hazards. However, capturing their occurrence with scientific instrumentation in a natural setting is extremely rare. The prevailing thinking on landslide initiation, particularly for those landslides that occur under intense precipitation, is that the failure surface is saturated and has positive pore-water pressures acting on it. Most analytic methods used for landslide hazard assessment are based on the above perception and assume that the failure surface is located beneath a water table. By monitoring the pore water and soil suction response to rainfall, we observed shallow landslide occurrence under partially saturated conditions for the first time in a natural setting. We show that the partially saturated shallow landslide at this site is predictable using measured soil suction and water content and a novel unified effective stress concept for partially saturated earth materials. Copyright 2009 by the American Geophysical Union.

  15. Basalt-Trachybasalt Fractionation in Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Bridges, J. C.; Edwards, P. H.; Filiberto, J.; Schwenzer, S. P.; Gasda, P.; Wiens, R.

    2016-08-01

    A set of igneous float rocks in Gale Crater have been analysed by ChemCam. They are basalt-trachybasalts, 47 to 53 ± 5 wt% SiO2 and formed by ol-dominated crystal fractionation from an Adirondack type basalt, in magmatism with tholeiitic affinities.

  16. Submarine basalt from the Revillagigedo Islands region, Mexico

    USGS Publications Warehouse

    Moore, J.G.

    1970-01-01

    Ocean-floor dredging and submarine photography in the Revillagigedo region off the west coast of Mexico reveal that the dominant exposed rock of the submarine part of the large island-forming volcanoes (Roca Partida and San Benedicto) is a uniform alkali pillow basalt; more siliceous rocks are exposed on the upper, subaerial parts of the volcanoes. Basalts dredged from smaller seamounts along the Clarion fracture zone south of the Revillagigedo Islands are tholeiitic pillow basalts. Pillows of alkali basalts are more vesicular than Hawaiian tholeiitic pillows collected from the same depths. This difference probably reflects a higher original volatile content of the alkali basalts. Manganese-iron oxide nodules common in several dredge hauls generally contain nucleii of rhyolitic pumice or basalt pillow fragments. The pumice floated to its present site from subaerial eruptions, became waterlogged and sank, and was then coated with manganese-iron oxides. The thickness of palagonite rinds on the glassy pillow fragments is proportional to the thickness of manganese-iron oxide layers, and both are a measure of the age of the nodule. Both oldest basalts (10-100 m.y.) and youngest (less than 1 m.y.) are along the Clarion fracture zone, whereas basalts from Roca Partida and San Benedicto volcanoes are of intermediate age. ?? 1970.

  17. Constructibility issues associated with a nuclear waste repository in basalt

    SciTech Connect

    Turner, D.A.

    1981-12-04

    This report contains the text and slide reproductions of a speech on nuclear waste disposal in basalt. The presentation addresses the layout of repository access shafts and subsurface facilities resulting from the conceptual design of a nuclear repository in basalt. The constructibility issues that must be resolved prior to construction are described. (DMC)

  18. Germanium abundances in lunar basalts: Evidence of mantle metasomatism

    SciTech Connect

    Dickinson, T.; Taylor, G.J.; Keil, T.K.; Bild, R.W.

    1988-01-01

    To fill in gaps in the present Ge data base, mare basalts were analyzed for Ge and other elements by RNAA and INAA. Mare basalts from Apollo 11, 12, 15, 17 landing sites are rather uniform in Ge abundance, but Apollo 14 aluminous mare basalts and KREEP are enriched in Ge by factors of up to 300 compared to typical mare basalts. These Ge enrichments are not associated with other siderophile element enrichments and, thus, are not due to differences in the amount of metal segregated during core formation. Based on crystal-chemical and inter-element variations, it does not appear that the observed Ge enrichments are due to silicate liquid immiscibility. Elemental ratios in Apollo 14 aluminous mare basalts, green and orange glass, average basalts and KREEP suggest that incorporation of late accreting material into the source regions or interaction of the magmas with primitive undifferentiated material is not a likely cause for the observed Ge enrichments. We speculate that the most plausible explanation for these Ge enrichments is complexing and concentration of Ge by F, Cl or S in volatile phases. In this manner, the KREEP basalt source regions may have been metasomatized and Apollo 14 aluminous mare basalt magmas may have become enriched in Ge by interacting with these metasomatized areas. The presence of volatile- and Ge-rich regions in the Moon suggests that the Moon was never totally molten. 71 refs., 1 fig., 6 tabs.

  19. Synthesis and optical properties of sulfide nanoparticles prepared in dimethylsulfoxide.

    PubMed

    Li, Yuebin; Ma, Lun; Zhang, Xing; Joly, Alan G; Liu, Zuli; Chen, Wei

    2008-11-01

    Many methods have been reported for the formation of sulfide nanoparticles by the reaction of metallic salts with sulfide chemical sources in aqueous solutions or organic solvents. Here, we report the formation of sulfide nanoparticles in dimethylsulfoxide (DMSO) by boiling metallic salts without sulfide sources. The sulfide sources are generated from the boiling of DMSO and react with metallic salts to form sulfide nanoparticles. In this method DMSO functions as a solvent and a sulfide source as well as a stabilizer for the formation of the nanoparticles. The recipe is simple and economical making sulfide nanoparticles formed in this way readily available for many potential applications.

  20. 40 CFR 425.03 - Sulfide analytical methods and applicability.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Provisions § 425.03 Sulfide analytical methods and applicability. (a) The potassium ferricyanide titration... the potassium ferricyanide titration method for the determination of sulfide in wastewaters...

  1. 40 CFR 425.03 - Sulfide analytical methods and applicability.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Provisions § 425.03 Sulfide analytical methods and applicability. (a) The potassium ferricyanide titration... the potassium ferricyanide titration method for the determination of sulfide in wastewaters...

  2. 40 CFR 425.03 - Sulfide analytical methods and applicability.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Provisions § 425.03 Sulfide analytical methods and applicability. (a) The potassium ferricyanide titration... the potassium ferricyanide titration method for the determination of sulfide in wastewaters...

  3. Synthesis and Optical Properties of Sulfide Nanoparticles Prepared in Dimethylsulfoxide

    SciTech Connect

    Li, Yuebin; Ma, Lun; Zhang, Xing; Joly, Alan G.; Liu, Zuli; Chen, Wei

    2008-11-01

    Many methods have been reported for the formation of sulfide nanoparticles by the reaction of metallic salts with sulfide chemical sources in aqueous solutions or organic solvents. Here, we report the formation of sulfide nanoparticles in dimethylsulfoxide (DMSO) by boiling metallic salts without sulfide sources. The sulfide sources are generated from the boiling of DMSO and react with metallic salts to form sulfide nanoparticles. In this method DMSO functions as a solvent and a sulfide source as well as a stabilizer for the formation of the nanoparticles. The recipe is simple and economical making sulfide nanoparticles formed in this way readily available for many potential applications.

  4. Study of microorganisms/basaltic crust interactions at hydrothermal vents and abyssal environments by an in situ experimental approach

    NASA Astrophysics Data System (ADS)

    Henri, P. A.; Rommevaux, C.; Menez, B.; Lesongeur, F.; Godfroy, A.

    2013-12-01

    In the dark ocean, microbial communities must thrive on organic matter coming from the photic zone or on redox reaction through chemosynthesis. Chemosynthetic microorganisms need to couple oxidized compounds, which are abundant in seawater, to reduced compounds. Near ocean ridges, newly formed basalt is enriched in these compounds. Even if the bioavailability is weak in glassy basalts, organisms can potentially alter the rock directly or indirectly by the use of these compounds (e.g. Fe2+, Mn2+) for their metabolisms. Moreover, the oceanic crust is highly hydrated by the oceanic circulation, and abiotic alteration, by hydration and redox reactions, contribute to make compounds bioavailable for organisms. To better discern abiotic and biotic implications and contribution in the early basalt alteration, we conducted an in situ experiment. Microbial incubators and abiotic controls containing synthetic MORB glasses of various compositions have been deployed since 2006 off-axis and in the vicinity of various vents of the Lucky Strike hydrothermal field (LS; 37°N-32°W, MAR) and recovered annually. This allows us to compare the biodiversity and the associated level of basalt alteration, according to the duration of in situ incubation (from only few weeks to more than two years) and the environmental parameters (particularly the level of hydrothermal fluid influence). The nature and the level of the microbial colonization of each sample are explored by pyrosequencing targeting the 16S RNAr gene. In parallel, the basalt alteration is characterized at the appropriate microscale using electronic, fluorescence and Raman microscopy/spectroscopy. These approaches allow to identify microbial species specifically associated with the alteration phases and to link alteration processes and microbial metabolisms and activity. We first evidence a close association between the different alteration phases at the basalt surface, and the presence of microbial cells, in favor of a

  5. Hydrothermal interactions of cesium and strontium phases from spent unreprocessed fuel with basalt phases and basalts

    SciTech Connect

    Komarneni, S.; Scheetz, B.E.; McCarthy, G.J.; Coons, W.E.

    1980-03-01

    This investigation is a segment of an extensive research program aimed at investigating the feasibility of long-term, subsurface storage of commercial nuclear waste. Specifically, it is anticipated that the waste will be housed in a repository mined from the basalt formations which lie beneath the Hanford Site. The elements monitored during the present experiments were Cs and Sr. These two elements represent significant biohazards if released from a repository and are the major heat producing radionuclides present in commercial radioactive waste. Several Cs phases and/or solutions were reacted with either isolated basalt phases or bulk-rock basalt, and the resulting solids and solutions were analyzed. The hydrothermal reactivity of SrZrO/sub 3/, which is believed to be a probable host for Sr in SFE was investigated. While so far no evidence exists which indicates that Sr is present in a water soluble phase in spent fuel elements (SFE), detailed investigation of a potential hazard is warranted. This investigation has determined that some Cs compounds likely to be stable components of spent fuel (i.e., CsOH, Cs/sub 2/MoO/sub 4/, Cs/sub 2/U/sub 2/O/sub 7/) have significant hydrothermal solubilities. These solubilities are greatly decreased in the presence of basalt and/or basalt minerals. The decrease in the amount of Cs in solution results from reactions which form pollucite and/or CsAlSiO/sub 4/, with the production of pollucite exceeding that of CsAlSiO/sub 4/. Dissolution of ..beta..-Cs/sub 2/U/sub 2/O/sub 7/ implies solubilizing a uranium species to an undetermined extent. The production of schoepite (UO/sub 3/.3H/sub 2/O) during some experiments containing basalt phases, indicates a tendency to oxidize U/sup 4 +/ to U/sup 6 +/. When diopside (nominally CaMgSi/sub 2/O/sub 6/) and ..beta..-Cs/sub 2/U/sub 2/O/sub 7/ were hydrothermally reacted, at 300/sup 0/C both UO/sub 2/ and UO/sub 3/.3H/sub 2/O were produced. Results of experiments on SrZrO/sub 3/ show it to be

  6. Variation in sulfide tolerance of photosystem II in phylogenetically diverse cyanobacteria from sulfidic habitats

    NASA Technical Reports Server (NTRS)

    Miller, Scott R.; Bebout, Brad M.

    2004-01-01

    Physiological and molecular phylogenetic approaches were used to investigate variation among 12 cyanobacterial strains in their tolerance of sulfide, an inhibitor of oxygenic photosynthesis. Cyanobacteria from sulfidic habitats were found to be phylogenetically diverse and exhibited an approximately 50-fold variation in photosystem II performance in the presence of sulfide. Whereas the degree of tolerance was positively correlated with sulfide levels in the environment, a strain's phenotype could not be predicted from the tolerance of its closest relatives. These observations suggest that sulfide tolerance is a dynamic trait primarily shaped by environmental variation. Despite differences in absolute tolerance, similarities among strains in the effects of sulfide on chlorophyll fluorescence induction indicated a common mode of toxicity. Based on similarities with treatments known to disrupt the oxygen-evolving complex, it was concluded that sulfide toxicity resulted from inhibition of the donor side of photosystem II.

  7. Differences between oceanic basalts by multitrace element ratio topology

    NASA Astrophysics Data System (ADS)

    Allegre, Claude J.; Schiano, Pierre; Lewin, Eric

    1995-01-01

    Trace element multidimensional analysis of ocean island basalts defines a structure delimited by the same four end members (Hawaiian Islands, St. Helena-Tubuai-Mangaia Islands, Kerguelen-Gough-Tristan da Cunha and the Society Islands) as determined by isotope ratios. In contrast to the results obtained for the distribution of isotopic ratios, the dispersions of trace element concentrations in mid-ocean ridge basalts are greater than those for ocean island basalts. This can be accounted for by a two-component mantle source composed of pyroxenite layers embedded in a peridotitic matrix, which melts to varying degrees; ocean island basalts are produced by a relatively uniform low degree of melting of the pyroxenite and limited isotopic exchange with the surrounding matrix, whereas mid-ocean ridge basalts are melts of both components with higher and more variable extents of melting and complete isotopic exchange between the pyroxenite strips and the peridotitic matrix.

  8. Origin of High-Alumina Basalt, Andesite, and Dacite Magmas.

    PubMed

    Hamilton, W

    1964-10-30

    The typical volcanic rocks of most island arcs and eugeosynclines, and of some continental environments, are basalt, andesite, and dacite, of high alumina content. The high-alumina basalt differs from tholeiitic basalt primarily in having a greater content of the components of calcic plagioclase. Laboratory data indicate that in the upper mantle, below the level at which the basaltic component of mantle rock is transformed by pressure to eclogite or pyroxenite, the entire basaltic portion probably is melted within a narrow temperature range, but that above the level of that transformation plagioclase is melted selectively before pyroxene over a wide temperature range. The broad spectrum of high-alumina magmas may represent widely varying degrees of partial melting above the transformation level, whereas narrow-spectrum tholeiite magma may represent more complete melting beneath it.

  9. [Determination of Total Iron and Fe2+ in Basalt].

    PubMed

    Liu, Jian-xun; Chen, Mei-rong; Jian, Zheng-guo; Wu, Gang; Wu, Zhi-shen

    2015-08-01

    Basalt is the raw material of basalt fiber. The content of FeO and Fe2O3 has a great impact on the properties of basalt fibers. ICP-OES and dichromate method were used to test total Fe and Fe(2+) in basalt. Suitable instrument parameters and analysis lines of Fe were chosen for ICP-OES. The relative standard deviation (RSD) of ICP-OES is 2.2%, and the recovery is in the range of 98%~101%. The method shows simple, rapid and highly accurate for determination of total Fe and Fe(2+) in basalt. The RSD of ICP-OES and dichromate method is 0.42% and 1.4%, respectively.

  10. Use and Features of Basalt Formations for Geologic Sequestration

    SciTech Connect

    McGrail, B. Peter; Ho, Anita M.; Reidel, Steve P.; Schaef, Herbert T.

    2003-01-01

    Extrusive lava flows of basalt are a potential host medium for geologic sequestration of anthropogenic CO2. Flood basalts and other large igneous provinces occur worldwide near population and power-producing centers and could securely sequester a significant fraction of global CO2 emissions. We describe the location, extent, and general physical and chemical characteristics of large igneous provinces that satisfy requirements as a good host medium for CO2 sequestration. Most lava flows have vesicular flow tops and bottoms as well as interflow zones that are porous and permeable and serve as regional aquifers. Additionally, basalt is iron-rich, and, under the proper conditions of groundwater pH, temperature, and pressure, injected CO2 will react with iron released from dissolution of primary minerals in the basalt to form stable ferrous carbonate minerals. Conversion of CO2 gas into a solid form was confirmed in laboratory experiments with supercritical CO2 in contact with basalt samples from Washington state.

  11. Ibitira: A basaltic achondrite from a distinct parent asteroid

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, David W.

    2004-01-01

    I have done detailed petrologic study of Ibitira, nominally classified as a basaltic eucrite. The Fe/Mn ratio of Ibitira pyroxenes with <10 mole % wollastonite component is 36.4 0.4, and is well-resolved from those of five basaltic eucrites studied for comparison; 31.2-32.2. Data for the latter completely overlap. Ibitira pyroxenes have lower Fe/Mg than the basaltic eucrite pyroxenes. Thus, the higher Fe/Mn ratio does not reflect a simple difference in oxidation state. Ibitira also has an oxygen isotopic composition, alkali element contents and a Ti/Hf ratio that distinguish it from basaltic eucrites. These differences support derivation from a distinct parent asteroid. Ibitira is the first recognized representative of the fifth known asteroidal basaltic crust.

  12. [Determination of Total Iron and Fe2+ in Basalt].

    PubMed

    Liu, Jian-xun; Chen, Mei-rong; Jian, Zheng-guo; Wu, Gang; Wu, Zhi-shen

    2015-08-01

    Basalt is the raw material of basalt fiber. The content of FeO and Fe2O3 has a great impact on the properties of basalt fibers. ICP-OES and dichromate method were used to test total Fe and Fe(2+) in basalt. Suitable instrument parameters and analysis lines of Fe were chosen for ICP-OES. The relative standard deviation (RSD) of ICP-OES is 2.2%, and the recovery is in the range of 98%~101%. The method shows simple, rapid and highly accurate for determination of total Fe and Fe(2+) in basalt. The RSD of ICP-OES and dichromate method is 0.42% and 1.4%, respectively. PMID:26672315

  13. Origin of High-Alumina Basalt, Andesite, and Dacite Magmas.

    PubMed

    Hamilton, W

    1964-10-30

    The typical volcanic rocks of most island arcs and eugeosynclines, and of some continental environments, are basalt, andesite, and dacite, of high alumina content. The high-alumina basalt differs from tholeiitic basalt primarily in having a greater content of the components of calcic plagioclase. Laboratory data indicate that in the upper mantle, below the level at which the basaltic component of mantle rock is transformed by pressure to eclogite or pyroxenite, the entire basaltic portion probably is melted within a narrow temperature range, but that above the level of that transformation plagioclase is melted selectively before pyroxene over a wide temperature range. The broad spectrum of high-alumina magmas may represent widely varying degrees of partial melting above the transformation level, whereas narrow-spectrum tholeiite magma may represent more complete melting beneath it. PMID:17794034

  14. Lu-Hf constraints on the evolution of lunar basalts

    NASA Technical Reports Server (NTRS)

    Fujimaki, H.; Tatsumoto, M.

    1984-01-01

    It is shown that a cumulate-remelting model best explains the recently acquired data on the Lu-Hf systematics of lunar mare basalts. The model is constructed using Lu and Hf concentration data and is strengthened by Hf isotopic evidence of Unruh et al. (1984). It is shown that the similarity in MgO/FeO ratios and Cr2O3 content in high-Ti and low-Ti basalts are not important constraints on lunar basalt petrogenesis. The model demonstrates that even the very low Ti or green glass samples are remelting products of a cumulate formed after at least 80-90 percent of the lunar magma ocean had solidified. In the model, all the mare basalts and green glasses were derived from 100-150 km depth in the lunar mantle. The Lu-Hf systematics of KREEP basalts clearly indicate that they would be the final residual liquid of the lunar magma ocean.

  15. Origin of high-alumina basalt, andesite, and dacite magmas

    USGS Publications Warehouse

    Hamilton, W.

    1964-01-01

    The typical volcanic rocks of most island arcs and eugeosynclines, and of some continental environments, are basalt, andesite, and dacite, of high alumina content. The high-alumina basalt differs from tholeiitic basalt primarily in having a greater content of the components of calcic plagioclase. Laboratory data indicate that in the upper mantle, below the level at which the basaltic component of mantle rock is transformed by pressure to eclogite or pyroxenite, the entire basaltic portion probably is melted within a narrow temperature range, but that above the level of that transformation plagioclase is melted selectively before pyroxene over a wide temperature range. The broad spectrum of high-alumina magmas may represent widely varying degrees of partial melting above the transformation level, whereas narrow-spectrum tholeiite magma may represent more complete melting beneath it.

  16. Composition of basalts from the Mid-Atlantic Ridge

    USGS Publications Warehouse

    Engel, A.E.J.; Engel, C.G.

    1964-01-01

    Studies of volcanic rocks in dredge hauls from the submerged parts of the Mid-Atlantic Ridge suggest that it consists largely of tholeiitic basalt with low values of K, Ti, and P. In contrast, the volcanic islands which form the elevated caps on the Ridge are built of alkali basalt with high values of Ti, Fe3+, P, Na, and K. This distinct correlation between the form of the volcanic structures, elevation above the sea floor, and composition suggests that the islands of alkali basalt are derived from a parent tholeiitic magma by differentiation in shallow reservoirs. The volume of low-potassium tholeiites along the Mid-Atlantic Ridge and elsewhere in the oceans appears to be many times that of the alkali basalts exposed on oceanic islands. Tholeiitic basalts with about 0.2 K2O appear to be the primary and predominant magma erupted on the oceanic floor.

  17. Conceptual Model of the Geometry and Physics of Water Flow in a Fractured Basalt Vadose Zone: Box Canyon Site, Idaho

    SciTech Connect

    Faybishenko, Boris; Doughty, Christine; Steiger, Michael; Long, Jane C.S.; Wood, Tom; Jacobsen, Janet; Lore, Jason; Zawislanski, Peter T.

    1999-03-01

    A conceptual model of the geometry and physics of water flow in a fractured basalt vadose zone was developed based on the results of lithological studies and a series of ponded infiltration tests conducted at the Box Canyon site near the Idaho National Engineering and Environmental Laboratory (INEEL) in Idaho. The infiltration tests included one two-week test in 1996, three two-day tests in 1997, and one four-day test in 1997. For the various tests, initial infiltration rates ranged from 4.1 cm/day to 17.7 cm/day and then decreased with time, presumably due to mechanical or microbiological clogging of fractures and vesicularbasalt in the near-surface zone, as well as the effect of entrapped air. The subsurface moisture redistribution was monitored with tensiometers, neutron logging, time domain reflectrometry and ground penetrating radar. A conservative tracer, potassium bromide, was added to the pond water at a concentration of 3 g/L to monitor water flow with electrical resistivity probes and water sampling. Analysis of the data showed evidence of preferential flow rather than the propagation of a uniform wetting front. We propose a conceptual model describing the saturation-desaturation behavior of the basalt, in which rapid preferential flow through vertical column-bounding fractures occurs from the surface to the base of the basalt flow. After the rapid wetting of column-bounding fractures, a gradual wetting of other fractures and the basalt matrix occurs. Fractures that are saturated early in the tests may become desaturated thereafter, which we attribute to the redistribution of water between fractures and matrix. Lateral movement of water was also observed within a horizontal central fracture zone and rubble zone, which could have important implications for contaminant accumulation at contaminated sites.

  18. Ammonia and hydrogen sulfide removal using biochar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reducing ammonia and hydrogen sulfide emissions from livestock facilities is an important issue for many communities and livestock producers. Ammonia has been regarded as odorous, precursor for particulate matter (PM), and contributed to livestock mortality. Hydrogen sulfide is highly toxic at elev...

  19. Sulfide oxidation under chemolithoautotrophic denitrifying conditions.

    PubMed

    Cardoso, Ricardo Beristain; Sierra-Alvarez, Reyes; Rowlette, Pieter; Flores, Elias Razo; Gómez, Jorge; Field, Jim A

    2006-12-20

    Chemolithoautotrophic denitrifying microorganisms oxidize reduced inorganic sulfur compounds coupled to the reduction of nitrate as an electron acceptor. These denitrifiers can be applied to the removal of nitrogen and/or sulfur contamination from wastewater, groundwater, and gaseous streams. This study investigated the physiology and kinetics of chemolithotrophic denitrification by an enrichment culture utilizing hydrogen sulfide, elemental sulfur, or thiosulfate as electron donor. Complete oxidation of sulfide to sulfate was observed when nitrate was supplemented at concentrations equal or exceeding the stoichiometric requirement. In contrast, sulfide was only partially oxidized to elemental sulfur when nitrate concentrations were limiting. Sulfide was found to inhibit chemolithotrophic sulfoxidation, decreasing rates by approximately 21-fold when the sulfide concentration increased from 2.5 to 10.0 mM, respectively. Addition of low levels of acetate (0.5 mM) enhanced denitrification and sulfate formation, suggesting that acetate was utilized as a carbon source by chemolithotrophic denitrifiers. The results of this study indicate the potential of chemolithotrophic denitrification for the removal of hydrogen sulfide. The sulfide/nitrate ratio can be used to control the fate of sulfide oxidation to either elemental sulfur or sulfate.

  20. 30 CFR 250.808 - Hydrogen sulfide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 2 2011-07-01 2011-07-01 false Hydrogen sulfide. 250.808 Section 250.808 Mineral Resources BUREAU OF OCEAN ENERGY MANAGEMENT, REGULATION, AND ENFORCEMENT, DEPARTMENT OF THE... Safety Systems § 250.808 Hydrogen sulfide. Production operations in zones known to contain...

  1. Impact of organic carbon on weathering and chemical denudation of granular basalt

    NASA Astrophysics Data System (ADS)

    Dontsova, Katerina; Zaharescu, Dragos; Henderson, Whitney; Verghese, Sarah; Perdrial, Nicolas; Hunt, Edward; Chorover, Jon

    2014-08-01

    Bench-scale experiments were conducted to determine rates and patterns of coupled organic matter infusion and weathering in a San Francisco volcanic field (Flagstaff, AZ) basalt sample under experimentally-modeled biotic and abiotic condition and to inform larger-scale collaborative studies at the landscape evolution observatory (LEO), Biosphere 2 (Tucson, AZ), where the same basaltic media is being used in a synthetic hillslope experiment. We postulated that mineral transformations depend significantly on the presence of organic carbon compounds including dissolved natural organic matter (DOM), with organic C simultaneously imprinting the chemical and mineralogical properties of primary and secondary solids undergoing incongruent dissolution. The present work reports on solute releases from Flagstaff basalt (FB) along laboratory-controlled gradients in DOM type and concentration. Loamy sand textured FB was subjected to flow-through, saturated column dissolution experiments using influent solutions with and without DOM compounds. Solutions included Ponderosa pine forest soil O-horizon extracts at three target concentrations: 7, 35, and 70 mg L-1 C, malic acid (MA) solutions at 7, 35, 70, and 140 mg L-1 C, and a control without DOM but having comparable inorganic solution composition. Chemical denudation rates for FB dissolution products were calculated from the concentration difference between outflow and inflow solutions. In addition, changes in the composition of the solid phase over the course of the experiment were determined using X-ray diffraction (XRD), X-ray fluorescence (XRF), and selective dissolution (SE). Column experiments supported dissolution rates derived from the literature and indicated a potentially strong effect of plant-derived organic ligands on mineral dissolution congruency and secondary phase precipitation. Both malic acid and DOM enhanced basalt dissolution, with malic acid having larger effect on per unit C basis. The largest relative

  2. Megacrystic Clinopyroxene Basalts Sample A Deep Crustal Underplate To The Mount Taylor Volcanic Field, New Mexico

    NASA Astrophysics Data System (ADS)

    Schmidt, M. E.; Schrader, C. M.; Crumpler, L. S.; Wolff, J. A.

    2012-12-01

    The alkaline and compositionally diverse (basanite to high-Si rhyolite) Mount Taylor Volcanic Field (MTVF), New Mexico comprises 4 regions that cover ~75 x 40 km2: (1) Mount Taylor, a large composite volcano and a surrounding field of basaltic vents; (2) Grants Ridge, constructed of topaz rhyolitic ignimbrite and coulees; (3) Mesa Chivato, a plateau of alkali basalts and mugearitic to trachytic domes; and (4) the Rio Puero basaltic necks. Distributed throughout its history (~3.6 to 1.26 Ma; Crumpler and Goff, 2012) and area (excepting Rio Puerco Necks) is a texturally distinct family of differentiated basalts (Mg# 43.2-53.4). These basalts contain resorbed and moth-eaten megacrysts (up to 2 cm) of plagioclase, clinopyroxene, and olivine ±Ti-magnetite ±ilmenite ±rare orthopyroxene. Some megacrystic lava flows have gabbroic cumulate inclusions with mineral compositions similar to the megacrysts, suggesting a common origin. For instance, gabbroic and megacrystic clinopyroxenes form linear positive arrays in TiO2 (0.2-2.3 wt%) with respect to Al2O3 (0.7-9.3 wt%). The lowest Al clinopyroxenes are found in a gabbroic inclusion and are associated with partially melted intercumulus orthopyroxene. Megacrystic and gabbroic plagioclase (An 41-80) in 4 representative thin sections were analyzed for 87Sr/86Sr by Laser Ablation ICP-MS. 87Sr/86Sr values for the suite range from 0.7036 to 0.7047. The low 87Sr/86Sr plagioclases (0.7036 to 0.7037) are associated with high Ti-Al clinopyroxenes. Likewise, the higher 87Sr/86Sr plagioclases (0.7043 to 0.7047) are associated with the low-Al clinopyroxenes. Taken together, these megacrysts track the differentiation of an intrusive body (or related bodies) from alkaline to Si-saturated conditions by fractional crystallization and crustal assimilation. The intrusive body likely underplates portions of the MTVF that have generated silicic magmas (Mount Taylor, Grants Ridge, Mesa Chivato). Although disequilibrium is implied by resorbed

  3. Vapor saturation and accumulation in magmas of the 1989-1990 eruption of Redoubt Volcano, Alaska

    USGS Publications Warehouse

    Gerlach, Terrance M.; Westrich, Henry R.; Casadevall, Thomas J.; Finnegan, David L.

    1994-01-01

    The 1989–1990 eruption of Redoubt Volcano, Alaska, provided an opportunity to compare petrologic estimates of SO2 and Cl emissions with estimates of SO2 emissions based on remote sensing data and estimates of Cl emissions based on plume sampling. In this study, we measure the sulfur and chlorine contents of melt inclusions and matrix glasses in the eruption products to determine petrologic estimates of SO2 and Cl emissions. We compare the results with emission estimates based on COSPEC and TOMS data for SO2 and data for Cl/SO2 in plume samples. For the explosive vent clearing period (December 14–22, 1989), the petrologic estimate for SO2 emission is 21,000 tons, or ~12% of a TOMS estimate of 175,000 tons. For the dome growth period (December 22, 1989 to mid-June 1990), the petrologic estimate for SO2 emission is 18,000 tons, or ~3% of COSPEC-based estimates of 572,000–680,000 tons. The petrologic estimates give a total SO2 emission of only 39,000 tons compared to an integrated TOMS/COSPEC emission estimate of ~1,000,000 tons for the whole eruption, including quiescent degassing after mid-June 1990. Petrologic estimates also appear to underestimate Cl emissions, but apparent HCl scavenging in the plume complicates Cl emission comparisons. Several potential sources of ‘excess sulfur’ often invoked to explain petrologic SO2 deficits are concluded to be unlikely for the 1989–1990 Redoubt eruption — e.g., breakdown of sulfides, breakdown of anhydrite, release of SO2 from a hydrothermal system, degassing of commingled infusions of basalt in the magma chamber, and syn-eruptive degassing of sulfur from melt present in non-erupted magma. Leakage and/or diffusion of sulfur from melt inclusions do not provide convincing explanations for the petrologic SO2 deficits either. The main cause of low petrologic estimates for SO2 is that melt inclusions do not represent the total sulfur content of the Redoubt magmas, which were vapor-saturated magmas carrying most of

  4. Flood basalt eruptions, comet showers, and mass extinction events

    NASA Technical Reports Server (NTRS)

    Rampino, Michael R.; Stothers, Richard B.

    1988-01-01

    A chronology of initiation dates of the major continental flood basalt episodes has been established from compilation of published K-Ar and Ar-Ar ages of basaltic flows and related basic intrusions. The dating is therefore independent of the biostratigraphic and paleomagnetic time scales, and the estimated errors of the inititation dates are approximately + or - 4 pct. There are 11 distinct episodes of continental flood basalts known during the past 250 Myr. The data show that flood basalt episodes are generally relatively brief geologic events, with intermittent eruptions during peak output periods lasting ony 2 to 3 Myr or less. Statistical analyses suggest that these episodes may have occurred quasi-periodically with a mean cycle time of 32 + or - 1 Myr. The initiation dates of the flood basalts are close to the estimated dates of marine mass extinctions and impact-crater clusters. Although a purely internal forcing might be argued for the flood basalt volcanism, quasi-periodic comet impacts may be the trigger for both the flood basalts and the extinctions. Impact cratering models suggest that large-body impactors lead to deep initial cratering, and therefore may cause mantle disturbances and initiate mantle plume activity. The flood basalt episodes commonly mark the initiation or jump of a mantle hotspot, and are often followed by continental rifting and separation. Evidence from dynamical studies of impacts, occurrences of craters and hotspots, and the geochemistry of boundary layers is synthesized to provide a possible model of impact-generated volcanism. Flood basalt eruptions may themselves have severe effects on climate, and possibly on life. Impacts might, as a result, have led to mass extinctions through direct atmospheric disturbances, and/or indirectly through prolonged flood basalt volcanism.

  5. Weathering of sulfides on Mars

    NASA Technical Reports Server (NTRS)

    Burns, Roger G.; Fisher, Duncan S.

    1987-01-01

    Pyrrhotite-pentlandite assemblages in mafic and ultramafic igneous rocks may have contributed significantly to the chemical weathering reactions that produce degradation products in the Martian regolith. By analogy and terrestrial processes, a model is proposed whereby supergene alteration of these primary Fe-Ni sulfides on Mars has generated secondary sulfides (e.g., pyrite) below the water table and produced acidic groundwater containing high concentrations of dissolved Fe, Ni, and sulfate ions. The low pH solutions also initiated weathering reactions of igneous feldspars and ferromagnesian silicates to form clay silicate and ferric oxyhydroxide phases. Near-surface oxidation and hydrolysis of ferric sulfato-and hydroxo-complex ions and sols formed gossan above the water table consisting of poorly crystalline hydrated ferric sulfates (e.g., jarosite), oxides (ferrihydrite, goethite), and silica (opal). Underlying groundwater, now permafrost contains hydroxo sulfato complexes of Fe, Al, Mg, Ni, which may be stabilized in frozen acidic solutions beneath the surface of Mars. Sublimation of permafrost may replenish colloidal ferric oxides, sulfates, and phyllosilicates during dust storms on Mars.

  6. Percutaneous absorption of selenium sulfide

    SciTech Connect

    Farley, J.; Skelly, E.M.; Weber, C.B.

    1986-01-01

    The purpose of this study was to determine selenium levels in the urine of Tinea patients before and after overnight application of a 2.5% selenium sulfide lotion. Selenium was measured by atomic absorption spectroscopy (AAS). Hydride generation and carbon rod atomization were studied. It was concluded from this study that selenium is absorbed through intact skin. Selenium is then excreted, at least partially, in urine, for at least a week following treatment. The data show that absorption and excretion of selenium vary on an individual basis. Selenium levels in urine following a single application of selenium sulfide lotion do not indicate that toxic amounts of selenium are being absorbed. Repeated treatments with SeS/sub 2/ result in selenium concentrations in urine which are significantly higher than normal. Significant matrix effects are observed in the carbon rod atomization of urine samples for selenium determinations, even in the presence of a matrix modifier such as nickel. The method of standard additions is required to obtain accurate results in the direct determination of selenium in urine by carbon rod AAS.

  7. Hydrogen sulfide pollution in wastewater treatment facilities

    SciTech Connect

    AlDhowalia, K.H. )

    1987-01-01

    The hydrogen sulfide (H{sub 2}S) found in wastewater collection systems and wastewater treatment facilities results from the bacterial reduction of the sulfate ion (SO{sub 4}). Hydrogen sulfide is a gas that occurs both in the sewer atmosphere and as a dissolved gas in the wastewater. When raw wastewater first enters the wastewater treatment facility by gravity most of the hydrogen sulfide is in the gaseous phase and will escape into the atmosphere at the inlet structures. Also some of the dissolved hydrogen sulfide will be released at points of turbulance such as at drops in flow, flumes, or aeration chambers. Several factors can cause excessive hydrogen sulfide concentrations in a sewerage system. These include septic sewage, long flow times in the sewerage system, high temperatures, flat sewer grades, and poor ventilation. These factors are discussed in this paper.

  8. Sulfide stress cracking susceptibility of nickel containing steels

    NASA Astrophysics Data System (ADS)

    Payer, J. H.; Pednekar, S. P.; Boyd, W. K.

    1986-09-01

    A systematic evaluation of the sulfide-stress cracking (SSC) behavior of five steels with nickel contents ranging from 0 to 3 pct was conducted in an acidified chloride solution saturated with H2S at room temperature (NACE solution). All of the steels were low-alloy, structural, or pressure vessel steels that are heat treatable to high strength levels with high toughness. All of the steels were heat treated to yield strength of approximately 690 MPa (100 ksi) and evaluated by identical test methods. The relative cracking susceptibility of the steels was determined from threshold stresses in constant-load tension tests and threshold stress intensities shown by precracked double-cantilever-beam specimens. Tempering treatment was a decisive factor in SSC susceptibility of low-nickel steels. When double tempered, low-Ni steels with greater than 1 pct Ni can be equivalent in SSC resistance to nominally nickel-free 4130 steel.

  9. Molybdenum Valence in Basaltic Silicate Melts

    NASA Technical Reports Server (NTRS)

    Danielson, L. R.; Righter, K.; Newville, M.; Sutton, S.; Pando, K.

    2010-01-01

    The moderately siderophile element molybdenum has been used as an indicator in planetary differentiation processes, and is particularly relevant to core formation [for example, 1-6]. However, models that apply experimental data to an equilibrium differentiation scenario infer the oxidation state of molybdenum from solubility data or from multivariable coefficients from metal-silicate partitioning data [1,3,7]. Partitioning behavior of molybdenum, a multivalent element with a transition near the J02 of interest for core formation (IW-2) will be sensitive to changes in JO2 of the system and silicate melt structure. In a silicate melt, Mo can occur in either 4+ or 6+ valence state, and Mo6+ can be either octahedrally or tetrahedrally coordinated. Here we present first XANES measurements of Mo valence in basaltic run products at a range of P, T, and JO2 and further quantify the valence transition of Mo.

  10. Chemical Weathering Kinetics of Basalt on Venus

    NASA Technical Reports Server (NTRS)

    Fegley, Bruce, Jr.

    1997-01-01

    The purpose of this project was to experimentally measure the kinetics for chemical weathering reactions involving basalt on Venus. The thermochemical reactions being studied are important for the CO2 atmosphere-lithosphere cycle on Venus and for the atmosphere-surface reactions controlling the oxidation state of the surface of Venus. These reactions include the formation of carbonate and scapolite minerals, and the oxidation of Fe-bearing minerals. These experiments and calculations are important for interpreting results from the Pioneer Venus, Magellan, Galileo flyby, Venera, and Vega missions to Venus, for interpreting results from Earth-based telescopic observations, and for the design of new Discovery class (e.g., VESAT) and New Millennium missions to Venus such as geochemical landers making in situ elemental and mineralogical analyses, and orbiters, probes and balloons making spectroscopic observations of the sub-cloud atmosphere of Venus.

  11. Silicate sulfidation and chemical differences between enstatite chondrites and Earth

    NASA Astrophysics Data System (ADS)

    Lehner, S. W.; Petaev, M. I.; Buseck, P. R.

    2013-12-01

    -sensitive material and contains minor elements such as Na, Ca, Mg, or Fe, which also occur in the adjacent minerals. Its high S content and vesicular nature point to formation by quenching of a high-temperature melt saturated with a gaseous phase. The porous silica occurs in ~50% of chondrules [12], metal-sulfide nodules, and as inter-chondrule clasts, suggesting it is a good tracer of silicate sulfidation. Refs: [1] Javoy M. (1995) GRL 22: 2219-2222. [2] Javoy M. et al. (2010) EPSL 293: 259-268. [3] Kaminski E. & Javoy M. (2013) EPSL 365: 97-107. [4] Jacobsen S.B. et al. (2013) LPSC 44: #2344. [5] Weisberg M.K. et al. (2011) GCA 75: 6556-6569. [6] Lehner S.W. et al. (2013) GCA 101: 34-56. [7] Simon S.B. et al. (2013) LPSC 44: #2270. [8] Lehner S.W. et al. (2012) LPSC 43: #2252. [9] Shahar A. et al. (2011) GCA 75: 7688-7697. [10] Kempl J. et al. (2013) EPSL 368: 61-68. [11] Fitoussi C. & Bourdon B. (2012) Science 335: 1477-1480. [12] Piani L. et al. (2013) MetSoc 76: # 5178.

  12. Giant Plagioclase "Mosaicrysts" and Other Textures in the Steens Basalt, Columbia River Flood Basalt Province

    NASA Astrophysics Data System (ADS)

    Grunder, A.; Moore, N. E.; Bohrson, W. A.

    2015-12-01

    The Steens Basalts (~16.7 Ma), the oldest and most mafic stage of Columbia River flood basalt volcanism, are known for lavas with conspicuous giant plagioclase laths (2 - 5 cm in diameter). Such flows are intercalated with ones that are nearly aphyric or that bear plagioclase (plag) phenocrysts of 0.5-2 cm. Addition textures are distinctive radial, snowflake plag clusters and sandwich glomerocrysts of plag, with olivine trapped between laths. These clusters and glomerocrysts are typically 1, but as large as 3 cm in diameter. Plag composition of all textural types is limited (An76-60). Plag dominates the phenocryst mode; rare flows, mainly low in the section, have olivine > plag and phenocrystic clinopyroxene occurs rarely, and mainly high in the section. Unlike the flows, dikes have few phenocrysts; giant laths are rare and the snowflake texture has not been observed. Giant plag laths are euhedral and make up a few percent to more than 50% of the rock. Many plag megacrysts are made of several plag crystals that form a mosaic, where the constituent crystals are crystallographically distinct and are overgrown with feldspar to make the crystal euhedral. We describe these composite megacrysts as "mosaicrysts". We are exploring magmatic conditions that would trigger oversaturation to spawn rapid growth yielding clusters and overgrowths that form mosaicrysts. Giant plagioclase basalts (so-called GPB) are also described for the Deccan and Emeishan flood basalt provinces attesting to similar magmatic processes. Plag laths typically define strong flow foliation at the flow base, have a swirled distribution in the flow core, and are sparse in the top. Some particularly crystal-rich flows (or sills) have an abrupt transition to a crystal-poor upper few decimeters of the several-m- thick flow. We interpret the crystal-poor top to be the expelled melt from crystal accumulation in the flow, which locally reinjects and is entrained in lower crystal mush.

  13. Isotope geochemistry of caliche developed on basalt

    NASA Astrophysics Data System (ADS)

    Knauth, L. Paul; Brilli, Mauro; Klonowski, Stan

    2003-01-01

    Enormous variations in oxygen and carbon isotopes occur in caliche developed on < 3 Ma basalts in 3 volcanic fields in Arizona, significantly extending the range of δ 18O and δ 13C observed in terrestrial caliche. Within each volcanic field, δ 18O is broadly co-variant with δ 13C and increases as δ 13C increases. The most 18O and 13C enriched samples are for subaerial calcite developed on pinnacles, knobs, and flow lobes that protrude above tephra and soil. The most 18O and 13C depleted samples are for pedogenic carbonate developed in soil atmospheres. The pedogenic caliche has δ 18O fixed by normal precipitation in local meteoric waters at ambient temperatures and has low δ 13C characteristic of microbial soil CO 2. Subaerial caliche has formed from 18O-rich evapoconcentrated meteoric waters that dried out on surfaces after local rains. The associated 13C enrichment is due either to removal of 12C by photosynthesizers in the evaporating drops or to kinetic isotope effects associated with evaporation. Caliche on basalt lava flows thus initially forms with the isotopic signature of evaporation and is subsequently over-layered during burial by calcite carrying the isotopic signature of the soil environment. The large change in carbon isotope composition in subsequent soil calcite defines an isotopic biosignature that should have developed in martian examples if Mars had a "warm, wet" early period and photosynthesizing microbes were present in the early soils. The approach can be similarly applied to terrestrial Precambrian paleocaliche in the search for the earliest record of life on land. Large variations reported for δ 18O of carbonate in Martian meteorite ALH84001 do not necessarily require high temperatures, playa lakes, or flood runoff if the carbonate is an example of altered martian caliche.

  14. Space-time relations of hydrothermal sulfide-sulfate-silica deposits at the northern Cleft Segment, Juan de Fuca Ridge

    SciTech Connect

    Koski, R.A.; Smith, V.K. ); Embley, R.W. ); Jonasson, I.R. ); Kadko, D.C. . Rosenstiel School of Marine and Atmospheric Science)

    1993-04-01

    Submersible investigations along the northern Cleft Segment of the Juan de Fuca Ridge indicate that a newly erupted sheet flow and two recent megaplume events are spatially related to a NNE-trending fissure system that is now the locus for active hydrothermal venting and deposition of massive sulfide mounds and chimneys. Samples from active high-temperature vent sites located east and north of the sheet flow terrain include zoned Cu-sulfide-rich chimneys (Type 1), bulbous anhydrite-rich chimneys (Type 2), and columnar Zn-sulfide-rich chimneys (Type 3). Type 1 chimneys with large open channelways result from the focused discharge of fluid at temperatures between 310 and 328 C from the Monolith sulfide mound. Type 2 chimneys are constructed on the Monolith and Fountain mounds where discharge of fluid at temperatures between 293 and 315 C is diffuse and sluggish. Type 3 chimneys, characterized by twisting narrow channelways, are deposited from focused and relatively low-temperature fluid discharging directly from basalt substrate. Inactive sulfide chimneys (Type 4) located within 100 m of the fissure system have bulk compositions, mineral assemblages, colloform and bacteroidal textures, and oxygen isotope characteristics consistent with low-temperature (< 250 C ) deposition from less robust vents. Field relations and [sup 210]Pb ages (> 100 years) indicate that the Type 4 chimneys formed prior to the sheet flow eruption. The sulfide mounds and Type 1 and Type 2 chimneys at the Monolith and Fountain vents, however, are an expression of the same magmatic event that caused the sheet flow eruption and megaplume events.

  15. Transferable potentials for phase equilibria. 8. United-atom description for thiols, sulfides, disulfides, and thiophene.

    PubMed

    Lubna, Nusrat; Kamath, Ganesh; Potoff, Jeffrey J; Rai, Neeraj; Siepmann, J Ilja

    2005-12-22

    An extension of the transferable potentials for phase equilibria united-atom (TraPPE-UA) force field to thiol, sulfide, and disulfide functionalities and thiophene is presented. In the TraPPE-UA force field, nonbonded interactions are governed by a Lennard-Jones plus fixed point charge functional form. Partial charges are determined through a CHELPG analysis of electrostatic potential energy surfaces derived from ab initio calculations at the HF/6-31g+(d,p) level. The Lennard-Jones well depth and size parameters for four new interaction sites, S (thiols), S(sulfides), S(disulfides), and S(thiophene), were determined by fitting simulation data to pure-component vapor-equilibrium data for methanethiol, dimethyl sulfide, dimethyl disulfide, and thiophene, respectively. Configurational-bias Monte Carlo simulations in the grand canonical ensemble combined with histogram-reweighting methods were used to calculate the vapor-liquid coexistence curves for methanethiol, ethanethiol, 2-methyl-1-propanethiol, 2-methyl-2-propanethiol, 2-butanethiol, pentanethiol, octanethiol, dimethyl sulfide, diethyl sulfide, ethylmethyl sulfide, dimethyl disulfide, diethyl disulfide, and thiophene. Excellent agreement with experiment is achieved, with unsigned errors of less than 1% for saturated liquid densities and less than 3% for critical temperatures. The normal boiling points were predicted to within 1% of experiment in most cases, although for certain molecules (pentanethiol) deviations as large as 5% were found. Additional calculations were performed to determine the pressure-composition behavior of ethanethiol+n-butane at 373.15 K and the temperature-composition behavior of 1-propanethiol+n-hexane at 1.01 bar. In each case, a good reproduction of experimental vapor-liquid equilibrium separation factors is achieved; both of the coexistence curves are somewhat shifted because of overprediction of the pure-component vapor pressures.

  16. Slow light and saturable absorption

    NASA Astrophysics Data System (ADS)

    Selden, A. C.

    2009-06-01

    Quantitative analysis of slow light experiments utilising coherent population oscillation (CPO) in a range of saturably absorbing media, including ruby and alexandrite, Er3+:Y2SiO5, bacteriorhodopsin, semiconductor quantum devices and erbium-doped optical fibres, shows that the observations may be more simply interpreted as saturable absorption phenomena. A basic two-level model of a saturable absorber displays all the effects normally associated with slow light, namely phase shift and modulation gain of the transmitted signal, hole burning in the modulation frequency spectrum and power broadening of the spectral hole, each arising from the finite response time of the non-linear absorption. Only where hole-burning in the optical spectrum is observed (using independent pump and probe beams), or pulse delays exceeding the limits set by saturable absorption are obtained, can reasonable confidence be placed in the observation of slow light in such experiments. Superluminal (“fast light”) phenomena in media with reverse saturable absorption (RSA) may be similarly explained.

  17. The phylogeny of endolithic microbes associated with marine basalts.

    PubMed

    Mason, Olivia U; Stingl, Ulrich; Wilhelm, Larry J; Moeseneder, Markus M; Di Meo-Savoie, Carol A; Fisk, Martin R; Giovannoni, Stephen J

    2007-10-01

    We examined the phylogenetic diversity of microbial communities associated with marine basalts, using over 300 publicly available 16S rDNA sequences and new sequence data from basalt enrichment cultures. Phylogenetic analysis provided support for 11 monophyletic clades originating from ocean crust (sediment, basalt and gabbro). Seven of the ocean crust clades (OCC) are bacterial, while the remaining four OCC are in the Marine Group I (MGI) Crenarchaeota. Most of the OCC were found at diverse geographic sites, suggesting that these microorganisms have cosmopolitan distributions. One OCC in the Crenarchaeota consisted of sequences derived entirely from basalts. The remaining OCC were found in both basalts and sediments. The MGI Crenarchaeota were observed in all studies where archaeal diversity was evaluated. These results demonstrate that basalts are occupied by cosmopolitan clades of microorganisms that are also found in marine sediments but are distinct from microorganisms found in other marine habitats, and that one OCC in the ubiquitous MGI Crenarchaeota clade may be an ecotype specifically adapted to basalt.

  18. Deep degassing and the eruptibility of flood basalt magmas

    NASA Astrophysics Data System (ADS)

    Black, B. A.; Manga, M.

    2015-12-01

    Individual flood basalt lavas often exceed 103 km3 in volume, and many such lavas erupt during emplacement of flood basalt provinces. The large volume of individual flood basalt lavas demands correspondingly large magma reservoirs within or at the base of the crust. To erupt, some fraction of this magma must become buoyant and overpressure must be sufficient to encourage failure and dike propagation. Because the overpressure associated with a new injection of magma is inversely proportional to the total reservoir volume, buoyancy overpressure has been proposed as a trigger for flood basalt eruptions. To test this hypothesis, we develop a new one-dimensional model for buoyancy overpressure-driven eruptions that combines volatile exsolution, bubble growth and rise, assimilation, and permeable fluid escape through the surrounding country rocks. Degassing during emplacement of flood basalt provinces may have major environmental repercussions. We investigate the temporal evolution of permeable degassing through the crust and degassing during eruptive episodes. We find that assimilation of volatile-rich country rocks strongly enhances flood basalt eruptibility, implying that the eruptive dynamics of flood basalts may be intertwined with their climatic consequences.

  19. The phylogeny of endolithic microbes associated with marine basalts.

    PubMed

    Mason, Olivia U; Stingl, Ulrich; Wilhelm, Larry J; Moeseneder, Markus M; Di Meo-Savoie, Carol A; Fisk, Martin R; Giovannoni, Stephen J

    2007-10-01

    We examined the phylogenetic diversity of microbial communities associated with marine basalts, using over 300 publicly available 16S rDNA sequences and new sequence data from basalt enrichment cultures. Phylogenetic analysis provided support for 11 monophyletic clades originating from ocean crust (sediment, basalt and gabbro). Seven of the ocean crust clades (OCC) are bacterial, while the remaining four OCC are in the Marine Group I (MGI) Crenarchaeota. Most of the OCC were found at diverse geographic sites, suggesting that these microorganisms have cosmopolitan distributions. One OCC in the Crenarchaeota consisted of sequences derived entirely from basalts. The remaining OCC were found in both basalts and sediments. The MGI Crenarchaeota were observed in all studies where archaeal diversity was evaluated. These results demonstrate that basalts are occupied by cosmopolitan clades of microorganisms that are also found in marine sediments but are distinct from microorganisms found in other marine habitats, and that one OCC in the ubiquitous MGI Crenarchaeota clade may be an ecotype specifically adapted to basalt. PMID:17803778

  20. Petrologic models of 15388, a unique Apollo 15 mare basalt

    NASA Technical Reports Server (NTRS)

    Hughes, S. S.; Dasch, E. J.; Nyquist, L. E.

    1993-01-01

    Mare basalt 15388, a feldspathic microgabbro from the Apennine Front, is chemically and petrographically distinct from Apollo 15 picritic, olivine-normative (ON), and quartz-normative basalts. The evolved chemistry, coarse texture, lack of olivine, and occurrence of cristobalite in 15388 argue for derivation by a late-stage magmatic process that is significantly removed from parental magma. It either crystallized from a magma evolved from the more mafic Apollo 15 basalts, or it crystallized from a currently unrepresented magma. Rb-Sr and Sm-Nd isotopic systematics yield isochron ages of 3.391 plus or minus 0.036 and 3.42 plus or minus 0.07 Ga, respectively, and epsilon(sub Nd) = 8.6 plus or minus 2.4, which is relatively high for Apollo 15 mare basalts. In contrast to chemical patterns of average Apollo 15 ON basalts and Apollo 15 picritic basalt, 15388 has a strongly positive LREE slope, high Ti, shallower HREE slope and a slightly positive Eu anomaly. These features argue against 15388 evolution by simple olivine fractionation of a parental ON or picritic basalt magma, although olivine is a dominant liquidus phase in both potential parents.

  1. Geochemistry, Petrology, and Provenance of Magnetite-Rich Ortaklar Cu Deposit Hosting Basalts from Koçali Complex, Gaziantep, Turkey

    NASA Astrophysics Data System (ADS)

    Yun, E.; Lee, I.; Kang, J.; Dönmez, C.; Yildirim, N.

    2015-12-01

    Magnetite-rich Cyprus type VMS deposit has been recently discovered from the Ortaklar-Gaziantep region within Koçali complex, SE Turkey. Magnetite rich sulfide ore bodies are in close contact with underlying footwall spilitic basalts. These basalts are part of Koçali mélange, which represents an accreted oceanic complex during closing of southern Neotethys. These extrusives are low-K, low alkali tholeiites with Ca rich, partially sericitized plagioclase subophitically enclosed by augite with disseminated Fe-Ti oxides and pyrite. Mineral crystallization sequence of plagioclase followed by augite and opaque is typical of MORB. Major and trace element analyses for least altered basalts based on LOI (1.5~3.6 wt%), Ce/Ce* (0.9~1.1) exhibit limited range of element abundances. Low Mg# (59~60) suggests that basalts were derived from moderately evolved magma with fractional crystallization. HFSE (Th, Nb, Hf, Zr) were used for tectonic discrimination and basalts were plotted within MORB end spectrum, near MORB-IAT boundary. N-MORB normalized La to Lu ranges from 0.4 to 0.9 times N-MORB with LREE depletion [(La/Sm)N = 0.58~0.67] and flat HREE [(Tb/Lu)N = 0.95~1.05]. Chondrite normalized REE patterns resemble those of N-MORB but characterized by severe LREE depletion [(La/Sm)CN = 0.35~0.45]. LREE depletion coupled with high Sm/Nd (0.36~0.43), high CaO/Na2O (5.0~6.2) and low Nb/Yb (0.23~0.39) suggest depleted N-MORB composition derived from the refractory mantle source. Analyzed basalts are similar to those found from other rift (Costa Rica Rift Hole 504b) and intra-transform fault (Siqueiros transform). Magnetite emplacement occurring close to the ore-host boundary and lack of pyrrhotite from hosting basalts imply an involvement of oxidized hydrothermal fluids. Basalts probably have formed by late stage, partial melting of the refractory mantle at low pressure, shallow depth, and H2O rich environment. Possible source of mantle heterogeneity can be identified by isotope

  2. Monitoring Microbe-Induced Sulfide Precipitation Under Dynamic Flow Conditions Using Multiple Geophysical Techniques

    NASA Astrophysics Data System (ADS)

    Williams, K. H.; Hubbard, S.; Ntarlagiannis, D.; Banfield, J.

    2004-05-01

    A laboratory study was undertaken to investigate the feasibility of using minimally invasive geophysical techniques to monitor microbe-induced sulfide precipitation in saturated sand-packed columns under dynamic flow conditions. Specifically, the effect of zinc and iron sulfide precipitation on geophysical signatures was evaluated during stimulated sulfate-reduction by Desulfovibrio vulgaris. Four inoculated columns and one non-inoculated control were operated under a continuous upward flow velocity of 50cm/day with the following measurements made: multi-port fluid sampling, cross-column acoustic wave propagation, induced polarization, time domain reflectometry and saturated hydraulic conductivity. Over a period of seven weeks, the onset and progression of sulfate reduction within the columns was confirmed through decreasing substrate and aqueous metals concentrations, increased biomass, and visible regions of sulfide accumulation. Decreases in initial lactate and sulfate concentrations (2.8mM and 4.0mM, respectively) followed predicted stoichiometric relationships and soluble Zn(II) and Fe(II) concentrations (0.31mM and 0.36mM, respectively) were reduced to levels below detection through sequestration as insoluble sulfide phases. The areas where sulfide precipitation and accumulation occurred resulted in significant changes in two of the three geophysical measurements. High frequency (400-600kHz) acoustic wave amplitudes were reduced by nearly an order of magnitude over the course of the experiment with no significant accompanying change in wave velocity. Neither the wave amplitudes nor the velocities changed significantly in the downgradient portions of the column where microbial activity and sulfide precipitation were depressed due to depleted substrate and metals concentrations. The frequency content of the transmitted waves remained unchanged throughout the course of the experiment. Over the frequency range of the induced polarization measurements (0.1-1000Hz

  3. Simulating infiltration tests in fractured basalt at the Box Canyon Site, Idaho

    SciTech Connect

    Unger, Andre J.A.; Faybishenko, Boris; Bodvarsson, Gudmundur S.; Simmons, Ardyth M.

    2003-04-01

    The results of a series of ponded infiltration tests in variably saturated fractured basalt at Box Canyon, Idaho, were used to build confidence in conceptual and numerical modeling approaches used to simulate infiltration in fractured rock. Specifically, we constructed a dual-permeability model using TOUGH2 to represent both the matrix and fracture continua of the upper basalt flow at the Box Canyon site. A consistent set of hydrogeological parameters was obtained by calibrating the model to infiltration front arrival times in the fracture continuum as inferred from bromide samples collected from fracture/borehole intersections observed during the infiltrating tests. These parameters included the permeability of the fracture and matrix continua, the interfacial area between the fracture and matrix continua, and the porosity of the fracture continuum. To calibrate the model, we multiplied the fracture-matrix interfacial area by a factor between 0.1 and 0.01 to reduce imbibition of water from the fracture continuum into the matrix continuum during the infiltration tests. Furthermore, the porosity of the fracture continuum, as calculated using the fracture aperture inferred from pneumatic-test permeabilities, was increased by a factor of 50 yielding porosity values for the upper basalt flow in the range of 0.01 to 0.02. The fracture-continuum porosity was a highly sensitive parameter controlling the arrival times of the simulated infiltration fronts. Porosity values are consistent with those determined during the Large-Scale Aquifer Pumping and Infiltration Test at the Idaho National Engineering and Environmental Laboratory.

  4. Hydrologic Responses to CO2 Injection in Basalts Based on Flow-through Experiments

    NASA Astrophysics Data System (ADS)

    Thomas, D.; Hingerl, F.; Garing, C.; Bird, D. K.; Benson, S. M.; Maher, K.

    2015-12-01

    Experimental studies of basalt-CO2 interactions have increased our ability to predict geochemical responses within a mafic reservoir during geologic CO2 sequestration. However, the lack of flow-through experiments prevents the use of coupled hydrologic-geochemical models to predict evolution of permeability and porosity, critical parameters for assessing storage feasibility. We present here results of three flow-through experiments on an intact basalt core during which we employed X-ray Computed Tomography (CT) to quantify porosity evolution and fluid flow. Using a single core of glassy basaltic tuff from the Snake River Plain (Menan Buttes complex), we performed tracer tests using a solution of NaI (~100,000 ppm) before and after injection of CO2-saturated water at reservoir conditions (90 bar, 50°C) to image porosity and flow path distribution. During the tracer tests, CT scans were taken at 2.5-minute intervals, and outlet fluid was discretely sampled at the same intervals and subsequently measured via ICP-MS, enabling interpretation of the tracer breakthrough curve through both imaging and geochemical analyses. Comparison of the porosity distribution from before and after injection of CO2 shows an overall decrease in core-averaged porosity from 34% to 31.1%. Permeability decreased exponentially from ~4.9x10-12 m2 to 1.18 x10-12 m2. The decrease in porosity and permeability suggests geochemical transformations in the mineral assemblage of the core, which we observe through petrographic analysis of an unaltered sample of the same lithology in contrast with the altered core. There is a significant increase in grain coatings, as well as reduction in the grain size, suggesting dissolution re-precipitation mechanisms. Finally, to develop a framework for the coupled geochemical and hydrologic responses observed experimentally, we have calibrated a reactive transport model at the core scale using the TOUGHREACT simulator [1]. [1] Xu et al. (2011) Comput. Geosci.

  5. Petrogenesis of Mare Basalts, Mg-Rich Suites and SNC Parent Magmas

    NASA Technical Reports Server (NTRS)

    Hess, Paul C.

    2004-01-01

    The successful models for the internal evolution of the Moon must consider the volume, distribution, timing, composition and, ultimately, the petrogenesis of mare basaltic volcanism. Indeed, given the paucity of geophysical data, the internal state of the Moon in the past can be gleaned only be unraveling the petrogenesis of the various igneous products on the Moon and, particularly, the mare basalts. most useful in constraining the depth and composition of their source region [Delano, 1980] despite having undergone a certain degree of shallow level olivine crystallization.The bulk of the lunar volcanic glass suite can be modeled as the partial melting products of an olivine + orthopyroxene source region deep within the lunar mantle. Ti02 contents vary from 0.2 wt % -1 7.0wt [Shearer and Papike, 1993]. Values that extreme would seem to require a Ti- bearing phase such as ilmenite in the source of the high-Ti (but not in the VLT source) because a source region of primitive LMO olivine and orthopyroxene, even when melted in small degrees cannot account for the observed range of Ti02 compositions. The picritic glasses are undersaturated with respect to ilmenite at all pressures investigated therefore ilmenite must have been consumed during melting, leaving an ilmenite free residue and an undersaturated melt [Delano, 1980, Longhi, 1992, Elkins et al, 2000 among others]. Multi- saturation pressures for the glasses potentially represent the last depths at which the liquids equilibrated with a harzburgite residue before ascending to the surface. These occur at great depths within the lunar mantle. Because the liquids have suffered some amount of crystal fractionation, this is at best a minimum depth. If the melts are mixtures, then it is only an average depth of melting. Multisaturation, nevertheless, is still a strong constraint on source mineralogy, revealing that the generation of the lunar basalts was dominated by melting of olivine and orthopyroxene.

  6. Sulfiding of hydrogel derived catalysts

    SciTech Connect

    Kemp, R.A.

    1991-11-05

    This patent describes a process for hydrotreating hydrocarbon feeds. It comprises contacting the feeds at a temperature in the range of from about 400{degrees} F. to about 850{degrees} F. and a pressure in the range of from about 400 psig to about 2500 psig with a catalyst having improved desulfurization activity prepared by incorporating an element selected from the group consisting of nickel, cobalt and mixtures thereof, and a heavy metal selected from the group consisting of molybdenum, tungsten and mixtures thereof, into an alumina hydrogel containing a phosphorous-containing compound, and sulfiding the catalyst with a gaseous sulfur compound at a temperature of at least about 900{degrees} F. for at least one hour.

  7. Pelletizing of sulfide molybdenite concentrates

    NASA Astrophysics Data System (ADS)

    Palant, A. A.

    2007-04-01

    The results of a pelletizing investigation using various binding components (water, syrup, sulfite-alcohol distillery grains, and bentonite) of the flotation sulfide molybdenite concentrate (˜84% MoS2) from the Mongolian deposit are discussed. The use of syrup provides rather high-strength pellets (>3 N/pellet or >300 g/pellet) of the required size (2 3 mm) for the consumption of 1 kg binder per 100 kg concentrate. The main advantage of the use of syrup instead of bentonite is that the molybdenum cinder produced by oxidizing roasting of raw ore materials is not impoverished due to complete burning out of the syrup. This fact exerts a positive effect on the subsequent hydrometallurgical process, decreasing molybdenum losses related to dump cakes.

  8. [Hydrogen sulfide and penile erection].

    PubMed

    Huang, Yi-Ming; Cheng, Yong; Jiang, Rui

    2012-09-01

    Hydrogen sulfide (H2S) is the third type of active endogenous gaseous signal molecule following nitric oxide (NO) and carbon monoxide (CO). In mammalians, H2S is mainly synthesized by two proteases, cystathionine-beta-synthase (CBS) and cystathionine-gamma-lyase (CSE). H2S plays an essential function of physiological regulation in vivo, and promotes penile erection by acting on the ATP-sensitive potassium channels to relax the vascular smooth muscle as well as by the synergistic effect with testosterone and NO to relax the corpus cavernosum smooth muscle (CCSM). At present, the selective phosphodiesterase type 5 (PDE5) inhibitor is mainly used for the treatment of erectile dysfunction (ED), but some ED patients fail to respond. Therefore, further studies on the mechanism of H2S regulating penile erection may provide a new way for the management of erectile dysfunction.

  9. Structural studies in limestone sulfidation

    SciTech Connect

    Fenouil, L.A.; Lynn, S.

    1993-05-01

    This study investigates the sulfidation of limestone at high temperatures (700--900{degree}C) as the first step in the design of a High-Temperature Coal-Gas Clean-Up system using millimeter-size limestone particles. Several workers have found that the rate of this reaction significantly decreases after an initial 10 to 15% conversion of CaCO{sub 3} to CaS. The present work attempts to explain this feature. It is first established that millimeter-size limestone particles do not sinter at temperatures up to the CaCO{sub 3} calcination point (899{degree}C at 1.03 bar CO{sub 2} partial pressure). It is then shown that CaS sinters rapidly at 750 to 900{degree}C if CO{sub 2} is present in the gas phase. Scanning Electron Microscope (SEM) photographs and Electron Dispersive Spectroscopy (EDS) data reveal that the CaS product layer sinters and forms a quasi-impermeable coating around the CaCO{sub 3} grains that greatly hinders more H{sub 2}S from reaching the still unreacted parts of the stone. Moreover, most of the pores initially present within the limestone structure begin to disappear or, at least, are significantly reduced in size. From then on, subsequent conversion is limited by diffusion of H{sub 2}S through the CaS layer, possibly by S{sup 2{minus}} ionic diffusion. The kinetics is then adequately described by a shrinking-core model, in which a sharp front of completely converted limestone is assumed to progress toward the center of the pellet. Finally, experimental evidence and computer simulations using simple sintering models suggest that the CaS sintering, responsible for the sharp decrease in the sulfidation rate, is surface-diffusion controlled.

  10. Saturation and pulsed FEL dynamics

    SciTech Connect

    Giannessi, L.; Mezi, L.

    1995-12-31

    The behavior of a FEL operating in the saturated pulsed regime, may be reproduced by the linear FEL integral equation, suitably modified to include saturation effects through a gain depression coefficient depending on the laser intensity. This simple method allows to evaluate several FEL parameters like gain, efficiency, band-width and optical pulse duration as functions of the optical cavity length, only with a numerical integration. The predictions have been compared with available experimental and numerical data, and the method has been applied to estimate the operating characteristics of some planned FEL experiments.

  11. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  12. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  13. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  14. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide is zinc sulfide containing a copper activator....

  15. 21 CFR 177.2490 - Polyphenylene sulfide resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyphenylene sulfide resins. 177.2490 Section 177... Components of Articles Intended for Repeated Use § 177.2490 Polyphenylene sulfide resins. Polyphenylene sulfide resins (poly(1,4-phenylene sulfide) resins) may be safely used as coatings or components...

  16. Modeling Cooling Rates of Martian Flood Basalt Columns

    NASA Astrophysics Data System (ADS)

    Weiss, D. K.; Jackson, B.; Milazzo, M. P.; Barnes, J. W.

    2011-12-01

    Columnar jointing in large basalt flows have been extensively studied and can provide important clues about the emplacement conditions and cooling history of a basalt flow. The recent discovery of basalt columns on Mars in crater walls near Marte Vallis provides an opportunity to infer conditions on early Mars when the Martian basalt flows were laid down. Comparison of the Martian columns to Earth analogs allows us to gain further insight into the early Martian climate, and among the best terrestrial analogs are the basalt columns in the Columbia River Basalt Group (CRBG) in eastern Washington. The CRBG is one of the youngest (< 17 Myrs old) and most extensively studied basalt provinces in the world, extending over 163,700 square km with total thickness exceeding 1 km in some places. The morphologies and textures of CRBG basalt columns suggest that in many places flows ~100 m thick cooled at uniform rates, even deep in the flow interior. Such cooling seems to require the presence of water in the column joints since the flow interiors should have cooled much more slowly than the flow margins if conductive cooling dominated. Secondary features, such pillow basalts, likewise suggest the basalt flows were in direct contact with standing water in many places. At the resolution provided by the orbiting HiRISE camera (0.9 m), the Martian basalt columns resemble the CRBG columns in many respects, and so, subject to important caveats, inferences linking the morphologies of the CRBG columns to their thermal histories can be extended in some respects to the Martian columns. In this presentation, we will describe our analysis of the HiRISE images of the Martian columns and what can be reasonably inferred about their thermal histories and the conditions under which they were emplaced. We will also report on a field expedition to the CRBG in eastern Washington State. During that expedition, we surveyed basalt column outcrops on the ground and from the air using Unmanned Aerial

  17. Mineral chemistry of Pangidi basalt flows from Andhra Pradesh

    NASA Astrophysics Data System (ADS)

    Nageswara Rao, P. V.; Swaroop, P. C.; Karimulla, Syed

    2012-04-01

    This paper elucidates the compositional studies on clinopyroxene, plagioclase, titaniferous magnetite and ilmenite of basalts of Pangidi area to understand the geothermometry and oxybarometry conditions. Petrographic evidence and anorthite content (up to 85%) of plagioclase and temperature estimates of clinopyroxene indicate that the clinopyroxene is crystallized later than or together with plagioclase. The higher An content indicates that the parent magma is tholeiitic composition. The equilibration temperatures of clinopyroxene (1110-1190°C) and titaniferous magnetite and ilmenite coexisting mineral phases (1063-1103°C) are almost similar in lower basalt flow and it is higher for clinopyroxene (900-1110°C) when compared to titaniferous magnetite and ilmenite coexisting mineral phases (748-898°C) in middle and upper basalt flows. From this it can be inferred that the clinopyroxene is crystallized earlier than Fe-Ti oxide phases reequilibration, which indicates that the clinopyroxene temperature is the approximate eruption temperature of the present lava flows. The wide range of temperatures (900-1190°C) attained by clinopyroxene may point out that the equilibration of clinopyroxene crystals initiated from depth till closer to the surface before the melt erupted. Pangidi basalts follow the QFM buffer curve which indicates the more evolved tholeiitic composition. This suggests the parent tholeiitic magma suffered limited fractionation at high temperature under increasing oxygen fugacity in lower basalt flow and more fractionation at medium to lower temperatures under decreasing oxygen fugacity conditions during cooling of middle and upper basalt flows. The variation of oxygen fugacity indicates the oxidizing conditions for lower basalt flow (9.48-10.3) and extremely reducing conditions for middle (12.1-15.5) and upper basalt (12.4-15.54) flows prevailed at the time of cooling. Temperature vs. (FeO+Fe2O3)/(FeO+Fe2O3 +MgO) data plots for present basalts suggested

  18. An Apollo 15 Mare Basalt Fragment and Lunar Mare Provinces

    NASA Technical Reports Server (NTRS)

    Ryder, Graham; Burling, Trina Cox

    1996-01-01

    Lunar sample 15474,4 is a tiny fragment of olivine-augite vitrophyre that is a mare basalt. Although petroraphically distinct from all other Apollo 15 samples, it has been ignored since its first brief description. Our new petrographic and mineral chemical data show that the olivines and pyroxenes are distinct from those in other basalts. The basalt cooled and solidified extremely rapidly; some of the olivine might be cumulate or crystallized prior to extrusion. Bulk-chemical data show that the sample is probably similar to an evolved Apollo 15 olivine-normative basalt in major elements but is distinct in its rare earth element pattern. Its chemical composition and petrography both show that 15474,4 cannot be derived from other Apollo 15 mare basalts by shallow-level crystal fractionation. It represents a distinct extrusion of magma. Nonetheless, the chemical features that 15474,4 has in common with other Apollo 15 mare basalts, including the high FeO/Sc, the general similarity of the rare earth element pattern, and the common (and chondritic) TiO2/Sm ratio, emphasize the concept of a geochemical province at the Apollo 15 site that is distinct from basalts and provinces elsewhere. In making a consistent picture for the derivation of all of the Apollo 15 basalts, both the commonalities and the differences among the basalts must be explained. The Apollo 15 commonalities and differences suggest that the sources must have consisted of major silicate phases with the same composition but with varied amounts of a magma trapped from a contemporary magma ocean. They probably had a high olivine/pyroxene ratio and underwent small and reasonably consistent degrees of partial melting to produce the basalts. These inferences may be inconsistent with models that suggest greatly different depths of melting among basalts, primitive sources for the green glasses, or extensive olivine fractionation during ascent. An integrated approach to lunar mare provinces, of which the Apollo 15

  19. Pliocene Basaltic Volcanism in The East Anatolia Region (EAR), Turkey

    NASA Astrophysics Data System (ADS)

    Oyan, Vural; Özdemir, Yavuz; Keskin, Mehmet

    2016-04-01

    East Anatolia Region (EAR) is one of the high Plateau which is occurred with north-south compressional regime formed depending on continent-continent collision between Eurasia and Arabia plates (Şengör and Kidd, 1979). Recent studies have revealed that last oceanic lithosphere in the EAR have completely depleted to 20 million years ago based on fission track ages (Okay et al. 2010). Our initial studies suggest that extensively volcanic activity in the EAR peaked in the Pliocene and continued in the same productivity throughout Quaternary. Voluminous basaltic lava plateaus and basaltic lavas from local eruption centers occurred as a result of high production level of volcanism during the Pliocene time interval. In order to better understand the spatial and temporal variations in Pliocene basaltic volcanism and to reveal isotopic composition, age and petrologic evolution of the basaltic volcanism, we have started to study basaltic volcanism in the East Anatolia within the framework of a TUBITAK project (project number:113Y406). Petrologic and geochemical studies carried out on the Pliocene basaltic lavas indicate the presence of subduction component in the mantle source, changing the character of basaltic volcanism from alkaline to subalkaline and increasing the amount of spinel peridotitic melts (contributions of lithospheric mantle?) in the mantle source between 5.5-3.5 Ma. FC, AFC and EC-AFC modelings reveal that the while basaltic lavas were no or slightly influenced by crustal contamination and fractional crystallization, to more evolved lavas such as bazaltictrachyandesite, basalticandesite, trachybasalt might have been important processes. Results of our melting models and isotopic analysis data (Sr, Nd, Pb, Hf, 18O) indicate that the Pliocene basaltic rocks were derived from both shallow and deep mantle sources with different melting degrees ranging between 0.1 - 4 %. The percentage of spinel seems to have increased in the mantle source of the basaltic

  20. Iron-induced hydroxyl radical generation from basaltic volcanic ash

    NASA Astrophysics Data System (ADS)

    Horwell, C. J.; Fenoglio, I.; Fubini, B.

    2007-09-01

    Iron-induced hydroxyl radical generation from the surface of volcanic ash particles is a possible mechanism of respiratory toxicity in addition to crystalline silica induced pathogenicity. Here we show that volcanic ash generates hydroxyl radicals, with greater reactivity in iron-rich, silica-poor samples, such as basaltic ash. Basaltic particles expose at the surface high levels of poorly-coordinated iron ions in both Fe(II) and Fe(III) oxidation states which are likely to be the cause of such reactivity. Hitherto, basaltic ash has been disregarded as a hazard due to the lack of crystalline silica particulate but future hazard assessment should consider its toxic potential.

  1. Basaltic volcanic episodes of the Yucca Mountain region

    SciTech Connect

    Crowe, B.M.

    1990-03-01

    The purpose of this paper is to summarize briefly the distribution and geologic characteristics of basaltic volcanism in the Yucca Mountain region during the last 10--12 Ma. This interval largely postdates the major period of silicic volcanism and coincides with and postdates the timing of major extensional faulting in the region. Field and geochronologic data for the basaltic rocks define two distinct episodes. The patterns in the volume and spatial distribution of these basaltic volcanic episodes in the central and southern part of the SNVF are used as a basis for forecasting potential future volcanic activity in vicinity of Yucca Mountain. 33 refs., 2 figs.

  2. Geology, mineralogy, and sulfur isotope geochemistry of the Sargaz Cu-Zn volcanogenic massive sulfide deposit, Sanandaj-Sirjan Zone, Iran

    NASA Astrophysics Data System (ADS)

    Badrzadeh, Zahra; Barrett, Timothy J.; Peter, Jan M.; Gimeno, Domingo; Sabzehei, Mossaieb; Aghazadeh, Mehraj

    2011-12-01

    The Sargaz Cu-Zn massive sulfide deposit is situated in the southeastern part of Kerman Province, in the southern Sanandaj-Sirjan Zone of Iran. The stratigraphic footwall of the Sargaz deposit is Upper Triassic to Lower Jurassic (?) pillowed basalt, whereas the stratigraphic hanging wall is andesite. Mafic volcanic rocks are overlain by andesitic volcaniclastics and volcanic breccias and locally by heterogeneous debris flows. Rhyodacitic flows and volcaniclastics overlie the sequence of basaltic and andesitic rocks. Based on the bimodal nature of volcanism, the regional geologic setting and petrochemistry of the volcanic rocks, we suggest massive sulfide mineralization in the Sargaz formed in a nascent ensialic back-arc basin. The current reserves (after ancient mining) of the Sargaz deposit are 3 Mt at 1.34% Cu, 0.38% Zn, 0.08%Pb, 0.24 g/t Au, and 7 g/t Ag. The structurally dismembered massive sulfide lens is zoned from a pyrite-rich base, to a pyrite ± chalcopyrite-rich central part, and a sphalerite-chalcopyrite-rich upper part, with a sphalerite-rich zone lateral to the upper part. The main sulfide mineral is pyrite, with lesser chalcopyrite and sphalerite. The feeder zone, comprised of a vein stockwork consists of quartz-sulfide-sericite pesudobreccia and, in the deepest part, chlorite-quartz-pyrite pesudobreccia. Footwall hydrothermal alteration extends at least 70-80 m below the massive sulfide lens and more than a hundred meters along strike from the massive sulfide lens. Jasper and Fe-Mn bearing chert horizons lateral to the sulfide deposit represent low-temperature hydrothermal precipitates of the evolving hydrothermal system. Based on mineral textures and paragenetic relationships, the growth history of the Sargaz deposit is complex and includes: (1) early precipitation of sulfides (protore) on the seafloor as precipitation of fine-grained anhedral pyrite, sphalerite, quartz, and barite; (2) anhydrite precipitation in open spaces and mineral interstices

  3. Mineralogical, petrological, and geochemical studies of the Limahe mafic-ultramatic intrusion and associated Ni-Cu sulfide ores, SW China

    NASA Astrophysics Data System (ADS)

    Tao, Yan; Li, Chusi; Song, Xie-Yan; Ripley, Edward M.

    2008-11-01

    The Limahe Ni-Cu sulfide deposit is hosted by a small mafic-ultramafic intrusion (800 × 200 × 300 m) that is temporally associated with the voluminous Permian flood basalts in SW China. The objective of this study is to better understand the origin of the deposit in the context of regional magmatism which is important for the ongoing mineral exploration in the region. The Limahe intrusion is a multiphase intrusion with an ultramafic unit at the base and a mafic unit at the top. The two rock units have intrusive contacts and exhibit similar mantle-normalized trace element patterns and Sr-Nd isotopic compositions but significantly different cumulus mineralogy and major element compositions. The similarities suggest that they are related to a common parental liquid, whereas the differences point to magma differentiation by olivine crystallization at depth. Sulfide mineralization is restricted to the ultramafic unit. The abundances of sulfides in the ultramafic unit generally increase towards the basal contacts with sedimentary footwall. The δ 34S values of sulfide minerals from the Limahe deposit are elevated, ranging from +2.4 to +5.4‰. These values suggest the involvement of external S with elevated δ 34S values. The mantle-normalized platinum-group element (PGE) patterns of bulk sulfide ores are similar to those of picrites associated with flood basalts in the region. The abundances of PGE in the sulfide ores, however, are significantly lower than that of sulfide liquid expected to segregate from undepleted picrite magma. Cr-spinel and olivine are present in the Limahe ultramafic rocks as well as in the picrites. Mantle-normalized trace element patterns of the Limahe intrusion generally resemble those of the picrites. However, negative Nb-Ta anomalies, common features of contamination with the lower or middle crust, are present in the intrusion but absent in the picrites. Sr-Nd isotopes suggest that the Limahe intrusion experienced higher degrees of

  4. Nanostructured lead sulfide: synthesis, structure and properties

    NASA Astrophysics Data System (ADS)

    Sadovnikov, S. I.; Gusev, A. I.; Rempel, A. A.

    2016-07-01

    The theoretical and experimental results of recent studies dealing with nanostructured lead sulfide are summarized and analyzed. The key methods for the synthesis of nanostructured lead sulfide are described. The crystal structure of PbS in nanopowders and nanofilms is discussed. The influence of the size of nanostructure elements on the optical and thermal properties of lead sulfide is considered. The dependence of the band gap of PbS on the nanoparticle (crystallite) size for powders and films is illustrated. The bibliography includes 222 references.

  5. Microbial control of hydrogen sulfide production

    SciTech Connect

    Montgomery, A.D.; Bhupathiraju, V.K.; Wofford, N.; McInerney, M.J.

    1995-12-31

    A sulfide-resistant strain of Thiobacillus denitrificans, strain F, prevented the accumulation of sulfide by Desulfovibrio desulfuricans when both organisms were grown in liquid medium. The wild-type strain of T. denitrificans did not prevent the accumulation of sulfide produced by D. desulfuricans. Strain F also prevented the accumulation of sulfide by a mixed population of sulfate-reducing bacteria enriched from an oil field brine. Fermentation balances showed that strain F stoichiometrically oxidized the sulfide produced by D. desulfuricans and the oil field brine enrichment to sulfate. The ability of a strain F to control sulfide production in an experimental system of cores and formation water from the Redfield, Iowa, natural gas storage facility was also investigated. A stable, sulfide-producing biofilm was established in two separate core systems, one of which was inoculated with strain F while the other core system (control) was treated in an identical manner, but was not inoculated with strain F. When formation water with 10 mM acetate and 5 mM nitrate was injected into both core systems, the effluent sulfide concentrations in the control core system ranged from 200 to 460 {mu}M. In the test core system inoculated with strain F, the effluent sulfide concentrations were lower, ranging from 70 to 110 {mu}M. In order to determine whether strain F could control sulfide production under optimal conditions for sulfate-reducing bacteria, the electron donor was changed to lactate and inorganic nutrients (nitrogen and phosphate sources) were added to the formation water. When nutrient-supplemented formation water with 3.1 mM lactate and 10 mM nitrate was used, the effluent sulfide concentrations of the control core system initially increased to about 3,800 {mu}M, and then decreased to about 1,100 {mu}M after 5 weeks. However, in the test core system inoculated with strain F, the effluent sulfide concentrations were much lower, 160 to 330 {mu}M.

  6. Microscale measurements of oxygen diffusion and consumption in subaqueous sulfide tailings

    NASA Astrophysics Data System (ADS)

    Elberling, Bo; Damgaard, Lars Riis

    2001-06-01

    The disposal of sulfide mine tailings in an environmentally sound, yet cost-effective, manner is an issue facing most metal mines. Subaqueous tailing disposal is considered an attractive option for disposal that limits oxygen (O 2) availability within sulfide mine tailings and controlling sulfide oxidation and the resultant acid mine drainage (AMD). Assuming that O 2 profiles represent steady-state conditions, we aim to evaluate the depth-dependent and temperature-dependent rates of O 2 consumption in saturated mine tailings. Measurements include microscale O 2 gradients and diffusivity profiles within columns representing undisturbed mine tailing profiles from an impoundment near Nanisivik Mine in northern Canada. Measurements were made across the diffusive boundary layer (DBL) above the tailing-water interface as well as in the tailings below. Laboratory measurements of O 2 profiles are compared to in situ profiles. From the laboratory results it is possible to evaluate the O 2 flux across the DBL and the depth-integrated O 2 uptake. The results are compared with the average sulfate production rate over 3 months. O 2 uptake in saturated tailings is discussed in relation to O 2 uptake measured in columns after free drainage. The methods applied provide consistent O 2 consumption rates as well as reliable predictions for controlling AMD by keeping tailings under water.

  7. Effect of Dissolved Organic Matter on Basalt Weathering Rates under Flow Conditions

    NASA Astrophysics Data System (ADS)

    Dontsova, K.; Steefel, C. I.; Chorover, J. D.

    2009-12-01

    Rock weathering is an important aspect of soil formation that is tightly coupled to the progressive colonization of grain surfaces by microorganisms and plant tissue, both of which are associated with the exudation of complexing ligands and reducing equivalents that are incorporated into dissolved organic matter. As part of a larger hillslope experimental study being designed for Biosphere 2 (Oracle, AZ), we seek to determine how the presence and concentration of dissolved organic matter affects the incongruent dissolution rates of basaltic tuff. Saturated flow column experiments are being conducted using plant-derived soluble organic matter solutions of variable concentrations, and comparisons are being made to experiments conducted with malic acid, a low-molecular weight organic acid commonly exuded into the rhizosphere. Dissolved organic matter was extracted from Ponderosa Pine forest floor and was characterized for aqueous geochemical parameters (pH, EC, ion balance, DOC/TN) and also for DOC composition (UV-Vis, FTIR spectroscopy). Column effluents are being analyzed for major and trace cations, anions, silica and organic solutes. Dissolution rates of primary minerals and precipitation rates of secondary phases will be estimated by fitting the data to a numerical reactive transport model, CrunchFlow2007. At the end of the fluid flow experiment, column materials will be analyzed for biogeochemical composition to detect preferential dissolution of specific phases, the precipitation of new ones, and to monitor the associated formation of biofilms. The influence of organic solutions on weathering patterns of basalt will be discussed.

  8. Stereo Pair: Basalt Cliffs, Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Basalt cliffs along the northwest edge of the Meseta de Somuncura plateau near Sierra Colorada, Argentina show an unusual and striking pattern of erosion. Stereoscopic observation helps to clarify the landform changing processes active here. Many of the cliffs appear to be rock staircases that have the same color as the plateau's basaltic cap rock. Are these the edges of lower layers in the basalt or are they a train of slivers that are breaking off from, then sliding downslope and away from, the cap rock. They appear to be the latter. Close inspection shows that each stair step is too laterally irregular to be a continuous sheet of bedrock like the cap rock. Also, the steps are not flat but instead are little ridges, as one might expect from broken, tilted, and sliding slices of the cap rock. Stream erosion has cut some gullies into the cliffs and green vegetation shows that water springs from and flows down some channels, but landsliding is clearly a major agent of erosion here.

    This cross-eyed stereoscopic image pair was generated using topographic data from the Shuttle Radar Topography Mission, combined with an enhanced Landsat 7satellite color image. The topography data are used to create two differing perspectives of a single image, one perspective for each eye. In doing so, each point in the image is shifted slightly, depending on its elevation. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7 Thematic Mapper image used here was provided to the SRTM project by the United States Geological Survey, Earth Resources Observation Systems (EROS) Data Center,Sioux Falls, South

  9. Calcium Sulfate in Atacama Desert Basalt: A Possible Analog for Bright Material in Adirondack Basalt, Gusev Crater

    NASA Technical Reports Server (NTRS)

    Sutter, B.; Golden, D. C.; Amundson, R.; Chong-Diaz, G.; Ming, D. W.

    2007-01-01

    The Atacama Desert in northern Chile is one of the driest deserts on Earth (< 2mm/y). The hyper-arid conditions allow extraordinary accumulations of sulfates, chlorides, and nitrates in Atacama soils. Examining salt accumulations in the Atacama may assist understanding salt accumulations on Mars. Recent work examining sulfate soils on basalt parent material observed white material in the interior vesicles of surface basalt. This is strikingly similar to the bright-white material present in veins and vesicles of the Adirondack basalt rocks at Gusev Crater which are presumed to consist of S, Cl, and/or Br. The abundance of soil gypsum/anhydrite in the area of the Atacama basalt suggested that the white material consisted of calcium sulfate (Ca-SO4) which was later confirmed by SEM/EDS analysis. This work examines the Ca-SO4 of Atacama basalt in an effort to provide insight into the possible nature of the bright material in the Adirondack basalt of Gusev Crater. The objectives of this work are to (i) discuss variations in Ca-SO4 crystal morphology in the vesicles and (ii) examine the Ca-SO4 interaction(s) with the basalt interior.

  10. A computational study of adhesion between rubber and metal sulfides at rubber-brass interface

    NASA Astrophysics Data System (ADS)

    Ling, Chian Ye; Hirvi, Janne T.; Suvanto, Mika; Bazhenov, Andrey S.; Ajoviita, Tommi; Markkula, Katriina; Pakkanen, Tapani A.

    2015-05-01

    Computational study at level of density functional theory has been carried out in order to investigate the adhesion between rubber and brass plated steel cord, which has high importance in tire manufacturing. Adsorption of natural rubber based adsorbate models has been studied on zinc sulfide, ZnS(1 1 0), and copper sulfide, Cu2S(1 1 1) and CuS(0 0 1), surfaces as the corresponding phases are formed in adhesive interlayer during rubber vulcanization. Saturated hydrocarbons exhibited weak interactions, whereas unsaturated hydrocarbons and sulfur-containing adsorbates interacted with the metal atoms of sulfide surfaces more strongly. Sulfur-containing adsorbates interacted with ZnS(1 1 0) surface stronger than unsaturated hydrocarbons, whereras both Cu2S(1 1 1) and CuS(0 0 1) surfaces showed opposite adsorption preference as unsaturated hydrocarbons adsorbed stronger than sulfur-containing adsorbates. The different interaction strength order can play role in rubber-brass adhesion with different relative sulfide concentrations. Moreover, Cu2S(1 1 1) surface exhibits higher adsorption energies than CuS(0 0 1) surface, possibly indicating dominant role of Cu2S in the adhesion between rubber and brass.

  11. Melt rock components in KREEPy breccia 15205: Petrography and mineral chemistry of KREEP basalts and quartz-normative mare basalts

    NASA Technical Reports Server (NTRS)

    Shervais, John W.; Vetter, Scott K.

    1993-01-01

    Many current models for the origin of lunar highland rocks feature as an essential component the assimilation of KREEPy material by primitive magmas parental to the Mg-rich suite and alkali suite plutonic rocks. Similar models have also been proposed for the origin of various mare basalt suites. However, any model which considers assimilation of KREEP an important petrologic process must sooner-or-later deal with the question: what is KREEP? Because pristine KREEP basalts are rare, and most known samples are small (e.g., 15382/15386), the geochemical variability of KREEP basalts is poorly known. Other KREEP compositions which are commonly used in these models include the hypothetical 'high-K KREEP' component of Warren and Wasson, which is derived from Apollo 14 soil data, and the 'superKREEP' quartz-monzodiorite 15405. Lunar breccia 15205 is a polymict regolith breccia that consists of approximately 20% KREEP basalt clasts and 20% quartz-normative basalt clasts in a KREEP-rich matrix. Bulk rock mixing calculations show that this sample comprises about 84% KREEP. The clasts range up to 1 cm in size, but most are considerably smaller. The primary aim is to characterize pristine KREEP basalts petrographically, to establish the range in chemical compositions of KREEP basalts, and to test models that were proposed for their origin. In addition, we may be able to extend the compositional range recognized in the quartz-normative basalt suite and cast some light on its origin as well. Preliminary whole rock geochemical data on the KREEP basalts are presented in a companion paper by M.M. Lindstrom and co-workers. Concentration is on petrography and mineral chemistry of these clasts, and the implications these data have for the origin of the different melt rock suites.

  12. Spreading and collapse of big basaltic volcanoes

    NASA Astrophysics Data System (ADS)

    Puglisi, Giuseppe; Bonforte, Alessandro; Guglielmino, Francesco; Peltier, Aline; Poland, Michael

    2016-04-01

    Among the different types of volcanoes, basaltic ones usually form the most voluminous edifices. Because volcanoes are growing on a pre-existing landscape, the geologic and structural framework of the basement (and earlier volcanic landforms) influences the stress regime, seismicity, and volcanic activity. Conversely, the masses of these volcanoes introduce a morphological anomaly that affects neighboring areas. Growth of a volcano disturbs the tectonic framework of the region, clamps and unclamps existing faults (some of which may be reactivated by the new stress field), and deforms the substratum. A volcano's weight on its basement can trigger edifice spreading and collapse that can affect populated areas even at significant distance. Volcano instability can also be driven by slow tectonic deformation and magmatic intrusion. The manifestations of instability span a range of temporal and spatial scales, ranging from slow creep on individual faults to large earthquakes affecting a broad area. In the frame of MED-SVU project, our work aims to investigate the relation between basement setting and volcanic activity and stability at three Supersite volcanoes: Etna (Sicily, Italy), Kilauea (Island of Hawaii, USA) and Piton de la Fournaise (La Reunion Island, France). These volcanoes host frequent eruptive activity (effusive and explosive) and share common features indicating lateral spreading and collapse, yet they are characterized by different morphologies, dimensions, and tectonic frameworks. For instance, the basaltic ocean island volcanoes of Kilauea and Piton de la Fournaise are near the active ends of long hotspot chains while Mt. Etna has developed at junction along a convergent margin between the African and Eurasian plates and a passive margin separating the oceanic Ionian crust from the African continental crust. Magma supply and plate velocity also differ in the three settings, as to the sizes of the edifices and the extents of their rift zones. These

  13. Investigation on laboratory and pilot-scale airlift sulfide oxidation reactor under varying sulfide loading rate.

    PubMed

    Pokasoowan, Chanya; Kanitchaidecha, Wilawan; K C, Bal Krishna; Annachhatre, Ajit P

    2009-01-01

    Airlift bioreactor was established for recovering sulfur from synthetic sulfide wastewater under controlled dissolved oxygen condition. The maximum recovered sulfur was 14.49 g/day when sulfide loading rate, dissolved oxygen (DO) and pH values were 2.97 kgHS(-)/m(3)-day, 0.2-1.0 mg/L and 7.2-7.8, respectively. On the other hand, the increase in recovered sulfur reduced the contact surface of sulfide oxidizing bacteria which affects the recovery process. This effect caused to reduce the conversion of sulfide to sulfur. More recovered sulfur was produced at high sulfide loading rate due to the change of metabolic pathway of sulfide-oxidizing bacteria which prevented the toxicity of sulfide in the culture. The maximum activity in this system was recorded to be about 3.28 kgS/kgVSS-day. The recovered sulfur contained organic compounds which were confirmed by the results from XRD and CHN analyzer. Afterwards, by annealing the recovered sulfur at 120 degrees C for 24 hrs under ambient Argon, the percentage of carbon reduced from 4.44% to 0.30%. Furthermore, the percentage of nitrogen and hydrogen decreased from 0.79% and 0.48% to 0.00% and 0.14%, respectively. This result showed the success in increasing the purity of recovered sulfur by using the annealing technique. The pilot-scale biological sulfide oxidation process was carried out using real wastewater from Thai Rayon Industry in Thailand. The airlift reactor successfully removed sulfide more than 90% of the influent sulfide at DO concentration of less than 0.1 mg/L, whereas the elementary sulfur production was 2.37 kgS/m(3)-day at sulfide loading rate of 2.14 kgHS(-)/m(3)-day. The sulfur production was still increasing as the reactor had not yet reached its maximum sulfide loading rate. PMID:19085599

  14. Low-velocity impact craters in ice and ice-saturated sand with implications for Martian crater count ages.

    USGS Publications Warehouse

    Croft, S.K.; Kieffer, S.W.; Ahrens, T.J.

    1979-01-01

    We produced a series of decimeter-sized impact craters in blocks of ice near 0oC and -70oC and in ice-saturated sand near -70oC as a preliminary investigation of cratering in materials analogous to those found on Mars and the outer solar satellites. Crater diameters in the ice-saturated sand were 2 times larger than craters in the same energy and velocity range in competent blocks of granite, basalt and cement. Craters in ice were c.3 times larger. Martian impact crater energy versus diameter scaling may thus be a function of latitude. -from Authors

  15. Glass structure and petrogenesis of high-titanium lunar basalts

    NASA Astrophysics Data System (ADS)

    Finnila, Aleta Berk

    Chapters 1 and 2 use characteristics of the lunar volcanic glass suites to elucidate their petrogenesis and the mineralogy of the lunar mantle. Chapter 1 discusses techniques for calculating the amount of crustal assimilation possible in lunar magma chambers and dikes based on thermal energy balances, kinetic rates, and simple fluid mechanical constraints. The discussion leads to the conclusion that only a small part of the total major element chemical variation in the mare basalt and volcanic glass collection is due to assimilation/fractional crystallization processes near the lunar surface. Chapter 2 analyses a series of piston-cylinder experiments conducted at pressures of 1.0 and 1.5 GPa where ilmenite was dissolved into a lunar red glass composition. The calculated ilmenite saturation surface and experimentally determined ilmenite-olivine cotectic are used to create a TiOsb2-(FeO+MgO)-SiOsb2 pseudo-ternary diagram at 1.0 and 1.5 GPa. These phase diagrams are used to constrain the origin of the high-titanium lunar basalt suite. The projection of the suite of pristine lunar glasses onto the olivine-orthopyroxene cotectic supports having a common deep source of orthopyroxene-olivine-ilmenite±diopside with every mineral except olivine or orthopyroxene being consumed during melt generation. The position and temperature of the ilmenite-olivine-orthopyroxene eutectic constrain melt compositions to having a maximum of approximately 17 wt.% TiOsb2. Chapters 3 and 4 use computer simulations to predict glass structure at the atomic level. Chapter 3 demonstrates the utility of the Monte Carlo simulation method called quantum annealing (QA). Because QA is a relatively new technique, the theory and implementation are described in detail. The QA results compare favorably to molecular dynamics (MD) simulations using the same boundary conditions. While the QA code is not very efficient on a serial architecture, the algorithm is almost perfectly parallel. Using the Cray-T3D

  16. Laboratory studies of Aedes aegypti (L.) attraction to ketones, sulfides and primary chloroalkanes tested alone and in combination with l-lactic acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The attraction of female Aedes aegypti to single compounds and binary compositions comprised of L-lactic acid and an additional saturated compound from a set of ketones, sulfides, and chloroalkanes was studied using a triple-cage dual-port olfactometer. These chemical classes were studied because o...

  17. Sulfidation of iron at high temperatures and diffusion kinetics in ferrous sulfide

    SciTech Connect

    Danielewski, M.; Mrowec, S.; Stoklosa, A.

    1982-02-01

    The kinetics and mechanism of iron sulfidation have been studied as a function of temperature (950-1200 K) and sulfur pressure (10/sup -3/ 0.065 atm). It has been stated that a compact Fe/sub 1-y/ S scale on iron grows according to the parabolic rate law as a result of outward lattice diffusion of metal ions through cation vacancies. The activation energy of sulfidation increases with sulfur pressure and the 1/n exponent increases with temperature. This nontypical dependence of iron sulfidation kinetics on temperature and pressure results from the analogous effect of both these parameters on defect concentration in ferrous sulfide. The chemical diffusion coefficients, D/sub FeS/ , and diffusion coefficients of defects, D/sub d/ , in ferrous sulfide have been calculated on the basis of parabolic rate contacts of iron sulfidation and deviations from stoichiometry in ferrous sulfide. It has been shown that D/sub FeS/ is practically independent of cation vacancy concentration whereas the diffusion coefficient of defects depends strongly on that parameter. A comparison of self-diffusion coefficients of iron in Fe/sub 1-y/ S calculated from the kinetics of iron sulfidation to those obtained from radioisotopic studies indicates that within the range studied of temperatures and sulfur vapor pressures the outward diffusion of iron across the scale occurs preferentially along the c axis of columnar ferrous sulfide crystals.

  18. Computation of EABF and EBF for basalt rock samples

    NASA Astrophysics Data System (ADS)

    Karabul, Yaşar; Amon Susam, Lidya; İçelli, Orhan; Eyecioğlu, Önder

    2015-10-01

    In this study, certain photon absorption parameters including the energy absorption buildup factor (EABF) and exposure buildup factor (EBF) have been investigated for three different basalt samples collected from different parts of Van city. Radiation shielding properties of the basalt samples indicated a strong correlation between photon energy absorption parameters and values of EABF and EBF of basalt samples. It was found that EABF and EBF parameters are related to radiation shielding properties of basalt samples. A new method and algorithm based on ZXCOM was used. Instead of calculating G-P fitting parameters for every effective atomic number (Zeff), EABF and EBF were calculated for Zeff by interpolation, using ANSI/ANS 6.4.3 standard data available for Zeff.

  19. Mineralogy of Silica Polymorphs in Basaltic Clasts in Eucrites

    NASA Astrophysics Data System (ADS)

    Ono, H.; Takenouchi, A.; Mikouchi, T.

    2016-08-01

    We analyzed silica polymorphs in basaltic clasts in Y-75011, Pasamonte and Stannern eucrites. Cristobalite and quartz have been found, which suggests wide occurrence of hydrothermal activity throughout the crust of Vesta.

  20. A Modified CIPW Norm Calculation for Lunar Mare Basalts

    NASA Technical Reports Server (NTRS)

    Milliken, R. E.; Basu, A.

    2000-01-01

    CIPW norms of lunar mare basalts are anomalously low in pyroxene. A modified norm calculation allowing higher Ca, Ti, Al, Cr, and Mn in di' and hy' obtains closer matches between normative and modal mineralogy.

  1. Systematics of Vanadium in Olivine from Planetary Basalts

    NASA Technical Reports Server (NTRS)

    Karner, J. M.; Papike, J. J.; Shearer, C. K.

    2002-01-01

    The systematics of vanadium in olivines from the Earth, Moon and Mars allows for the comparison of planetary basalt origin and igneous setting and process. Additional information is contained in the original extended abstract.

  2. Basaltic Cone Suggests Constructional Origin of Some Guyots.

    PubMed

    Christensen, M N; Gilbert, C M

    1964-01-17

    A basaltic cinder cone was built beneath the waters of Mono Lake in Pleistocene time. This cone is now exposed. Its internal structure, external form, and petrography suggest that it was constructed with a flat top.

  3. Basaltic Cone Suggests Constructional Origin of Some Guyots.

    PubMed

    Christensen, M N; Gilbert, C M

    1964-01-17

    A basaltic cinder cone was built beneath the waters of Mono Lake in Pleistocene time. This cone is now exposed. Its internal structure, external form, and petrography suggest that it was constructed with a flat top. PMID:17753148

  4. Experimental Confirmation of the Volatility of Germanium in Martian Basalts

    NASA Astrophysics Data System (ADS)

    Humayun, M.; DiFrancesco, N.; Ustunisik, G.

    2016-08-01

    Experimental degassing of a synthetic martian basalt doped with Ge and Zn resulted in nearly total loss of both elements after 6 hours of heating, implying that the Ge depletion in shergottites is complemented by Ge excesses in sedimentary rocks.

  5. [Comparative carcinogenic properties of basalt fiber and chrysotile-asbestos].

    PubMed

    Nikitina, O V; Kogan, F M; Vanchugova, N N; Frash, V N

    1989-01-01

    In order to eliminate asbestos adverse effect on workers' health it was necessary to use mineral rayon, primarily basalt fibre, instead of asbestos. During a chronic experiment on animals the oncogenicity of 2 kinds of basalt fibre was studied compared to chrysotile asbestos. The dust dose of 25 mg was twice administered by intraperitonial route. All types of dust induced the onset of intraperitonial mesotheliomas but neoplasm rates were significantly lower in the groups exposed to basalt fibre. There was no credible data on the differences between the groups exposed to various types of basalt fibre. Since the latter produced some oncogenic effect, it was necessary to develop a complex of antidust measures, fully corresponding to the measures adopted for carcinogenic dusts.

  6. Low temperature aqueous alteration of basalt: Mineral assemblages of Deccan basalts and implications for Mars

    NASA Astrophysics Data System (ADS)

    Greenberger, R. N.; Mustard, J. F.; Kumar, P. S.; Dyar, M. D.; Breves, E. A.; Sklute, E. C.

    2012-09-01

    Al-rich phyllosilicates (kaolinite, montmorillonite) have been found in layers overlying Fe/Mg-smectites on Mars, and it has been suggested that this stratigraphy formed through in situ leaching at the surface, similar to terrestrial weathering profiles. We are investigating the remotely sensed signatures of this type of weathering using ten samples from a vertical section of altered Deccan basalts and four samples collected nearby as an analog for leaching resulting in Al-rich phyllosilicate over Fe/Mg-smectite stratigraphies. Samples were analyzed with reflectance spectroscopy from 0.28 to 25.0 μm, inductively coupled plasma atomic emission spectrometry for 10 major element concentrations (Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti), loss on ignition for volatiles, x-ray diffraction (XRD) for mineralogies, and Mössbauer spectroscopy for Fe redox state. Spectra of basalt samples were dominated by Fe2+ crystal field transitions with weak alteration bands near 1.4 and/or 1.9 μm. Reststrahlen bands in mid-infrared showed the convolution of plagioclase and pyroxene features typical of basalts. Saprolite samples were incompletely leached, and their spectra were dominated by complex Al- and Fe/Mg-bearing smectite clays and retained no original mafic signatures. XRD and Mössbauer detected pyroxene and plagioclase not visible by reflectance spectroscopy in some saprolite samples. Zeolites were present throughout the saprolite. The laterite was the most leached horizon, and all analyses showed kaolinite and iron oxide assemblages. This kaolinite and hematite association would be expected if kaolinite on Mars formed through leaching under conditions similar to those on Earth and has implications for abundant freshwater on the Martian surface.

  7. Ridding Groundwater of Hydrogen Sulfide. Part 1.

    ERIC Educational Resources Information Center

    Lochrane, Thomas G.

    1979-01-01

    This article is the first in a series reviewing the problems associated with hydrogen sulfide in drinking water sources. Discussion centers on identification of a cost-effective balance between aeration and chlorination treatment operations. (AS)

  8. Selenium sulfide: adjunctive therapy for tinea capitis.

    PubMed

    Allen, H B; Honig, P J; Leyden, J J; McGinley, K J

    1982-01-01

    Selenium sulfide lotion used as a shampoo has been shown to be an effective adjunctive agent to griseofulvin in the treatment of tinea capitis. Of 16 children with Trichophyton tonsurans infections 15 had negative fungal cultures at two weeks following a regimen of daily oral griseofulvin and selenium sulfide shampooing twice weekly. All patients treated with griseofulvin alone or in combination with either a bland shampoo or topical clotrimazole had positive cultures not only at the two-week interval but also as long as eight weeks later. In vitro analysis shows selenium sulfide to be sporicidal, correlating well with the in vivo observations. It is postulated that selenium sulfide usage may lessen the chances for spreading of infectious spores to other individuals.

  9. Basalt Waste Isolation Project Reclamation Support Project:

    SciTech Connect

    Brandt, C.A.; Rickard, W.H. Jr.; Cadoret, N.A.

    1992-06-01

    The Basalt Waste Isolation Project (BWIP) Reclamation Support Project began in the spring of 1988 by categorizing sites distributed during operations of the BWIP into those requiring revegetation and those to be abandoned or transferred to other programs. The Pacific Northwest Laboratory's role in this project was to develop plans for reestablishing native vegetation on the first category of sites, to monitor the implementation of these plans, to evaluate the effectiveness of these efforts, and to identify remediation methods where necessary. The Reclamation Support Project focused on three major areas: geologic hydrologic boreholes, the Exploratory Shaft Facility (ESF), and the Near-Surface Test Facility (NSTF). A number of BWIP reclamation sites seeded between 1989 and 1990 were found to be far below reclamation objectives. These sites were remediated in 1991 using various seedbed treatments designed to rectify problems with water-holding capacity, herbicide activity, surficial crust formation, and nutrient imbalances. Remediation was conducted during November and early December 1991. Sites were examined on a monthly basis thereafter to evaluate plant growth responses to these treatments. At all remediation sites early plant growth responses to these treatments. At all remediation sites, early plant growth far exceeded any previously obtained using other methods and seedbed treatments. Seeded plants did best where amendments consisted of soil-plus-compost or fertilizer-only. Vegetation growth on Gable Mountain was less than that found on other areas nearby, but this difference is attributed primarily to the site's altitude and north-facing orientation.

  10. Hafnium isotope variations in oceanic basalts

    NASA Technical Reports Server (NTRS)

    Patchett, P. J.; Tatsumoto, M.

    1980-01-01

    Hafnium isotope ratios generated by the beta(-) decay of Lu-176 are investigated in volcanic rocks derived from the suboceanic mantle. Hf-176/Hf-177 and Lu/Hf ratios were determined to precisions of 0.01-0.04% and 0.5%, respectively, by routine, low-blank chemistry. The Hf-176/Hf-177 ratio is found to be positively correlated with the Nd-143/Nd-144 ratio and negatively correlated with the Sr-87/Sr-86 and Pb-206/Pb-204 ratios, and to increase southwards along the Iceland-Reykjanes ridge traverse. An approximate bulk earth Hf-176/Hf-177 ratio of 0.28295 is inferred from the bulk earth Nd-143/Nd-144 ratio, which requires a bulk earth Lu/Hf ratio of 0.25, similar to the Juvinas eucrite. Midocean ridge basalts are shown to account for 60% of the range of Hf isotope ratios, and it is suggested that Lu-Hf fractionation is decoupled from Sm-Nd and Rb-Sr fractionation in very trace-element-depleted source regions as a result of partial melting.

  11. Diversity of life in ocean floor basalt

    NASA Astrophysics Data System (ADS)

    Thorseth, I. H.; Torsvik, T.; Torsvik, V.; Daae, F. L.; Pedersen, R. B.

    2001-12-01

    Electron microscopy and biomolecular methods have been used to describe and identify microbial communities inhabiting the glassy margins of ocean floor basalts. The investigated samples were collected from a neovolcanic ridge and from older, sediment-covered lava flows in the rift valley of the Knipovich Ridge at a water depth around 3500 m and an ambient seawater temperature of -0.7°C. Successive stages from incipient microbial colonisation, to well-developed biofilms occur on fracture surfaces in the glassy margins. Observed microbial morphologies are various filamentous, coccoidal, oval, rod-shaped and stalked forms. Etch marks in the fresh glass, with form and size resembling the attached microbes, are common. Precipitation of alteration products around microbes has developed hollow subspherical and filamentous structures. These precipitates are often enriched in Fe and Mn. The presence of branching and twisted stalks that resemble those of the iron-oxidising Gallionella, indicate that reduced iron may be utilised in an energy metabolic process. Analysis of 16S-rRNA gene sequences from microbes present in the rock samples, show that the bacterial population inhabiting these samples cluster within the γ- and ɛ-Proteobacteria and the Cytophaga/Flexibacter/Bacteroides subdivision of the Bacteria, while the Archaea all belong to the Crenarchaeota kingdom. This microbial population appears to be characteristic for the rock and their closest relatives have previously been reported from cold marine waters in the Arctic and Antarctic, deep-sea sediments and hydrothermal environments.

  12. Lead isotope systematics of mare basalt 75075

    NASA Technical Reports Server (NTRS)

    Chen, J. H.; Tilton, G. R.; Mattinson, J. M.; Vidal, P.

    1978-01-01

    Uranium, thorium and isotopic lead data are reported for two bulk samples and separated pyroxene, ilmenite and plagioclase from basalt 75075. In a concordia diagram the whole rock, ilmenite and four pyroxene samples define a chord intersecting the concordia curve at approximately 4.25 and 2.8 AE. Three plagioclase samples plot distinctly off the chord. The crystallization age of 75075 is accurately determined at 3.74 AE by Rb-Sr, Sm-Nd and K-Ar measurements from other laboratories. It is not possible to adjust the isotopic composition of initial lead so as to reconcile the U-Pb data with a crystallization age of 3.74 AE. The data therefore indicate some type of post-crystallization disturbance of the U-Pb system that is not detected by the other systems. The 75075 data are one of the few examples of this type of age pattern found on the moon. If the disturbance was a single event, it probably occurred around 2.8 AE ago, the time indicated by the pyroxene, whole rock and ilmenite data.

  13. Radiolytic Hydrogen Production in the Subseafloor Basaltic Aquifer.

    PubMed

    Dzaugis, Mary E; Spivack, Arthur J; Dunlea, Ann G; Murray, Richard W; D'Hondt, Steven

    2016-01-01

    Hydrogen (H2) is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium ((238)U, (235)U), thorium ((232)Th) and potassium ((40)K). To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th, and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt) concentrations (which can vary between eruptive events) and post-emplacement alteration. However, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2 production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (>10 Ma) basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may support as

  14. Basalt: Biologic Analog Science Associated with Lava Terrains

    NASA Astrophysics Data System (ADS)

    Lim, D. S. S.; Abercromby, A.; Kobs-Nawotniak, S. E.; Kobayashi, L.; Hughes, S. S.; Chappell, S.; Bramall, N. E.; Deans, M. C.; Heldmann, J. L.; Downs, M.; Cockell, C. S.; Stevens, A. H.; Caldwell, B.; Hoffman, J.; Vadhavk, N.; Marquez, J.; Miller, M.; Squyres, S. W.; Lees, D. S.; Fong, T.; Cohen, T.; Smith, T.; Lee, G.; Frank, J.; Colaprete, A.

    2015-12-01

    This presentation will provide an overview of the BASALT (Biologic Analog Science Associated with Lava Terrains) program. BASALT research addresses Science, Science Operations, and Technology. Specifically, BASALT is focused on the investigation of terrestrial volcanic terrains and their habitability as analog environments for early and present-day Mars. Our scientific fieldwork is conducted under simulated Mars mission constraints to evaluate strategically selected concepts of operations (ConOps) and capabilities with respect to their anticipated value for the joint human and robotic exploration of Mars. a) Science: The BASALT science program is focused on understanding habitability conditions of early and present-day Mars in two relevant Mars-analog locations (the Southwest Rift Zone (SWRZ) and the East Rift Zone (ERZ) flows on the Big Island of Hawai'i and the eastern Snake River Plain (ESRP) in Idaho) to characterize and compare the physical and geochemical conditions of life in these environments and to learn how to seek, identify, and characterize life and life-related chemistry in basaltic environments representing these two epochs of martian history. b) Science Operations: The BASALT team will conduct real (non-simulated) biological and geological science at two high-fidelity Mars analogs, all within simulated Mars mission conditions (including communication latencies and bandwidth constraints) that are based on current architectural assumptions for Mars exploration missions. We will identify which human-robotic ConOps and supporting capabilities enable science return and discovery. c) Technology: BASALT will incorporate and evaluate technologies in to our field operations that are directly relevant to conducting the scientific investigations regarding life and life-related chemistry in Mars-analogous terrestrial environments. BASALT technologies include the use of mobile science platforms, extravehicular informatics, display technologies, communication

  15. Genesis of highland basalt breccias - A view from 66095

    NASA Technical Reports Server (NTRS)

    Garrison, J. R., Jr.; Taylor, L. A.

    1980-01-01

    Electron microprobe and defocused beam analyses of the lunar highland breccia sample 66095 show it consists of a fine-grained subophitic matrix containing a variety of mineral and lithic clasts, such as intergranular and cataclastic ANT, shocked and unshocked plagioclase, and basalts. Consideration of the chemistries of both matrix and clasts provides a basis for a qualitative three-component mixing model consisting of an ANT plutonic complex, a Fra Mauro basalt, and minor meteoric material.

  16. Radiolytic Hydrogen Production in the Subseafloor Basaltic Aquifer.

    PubMed

    Dzaugis, Mary E; Spivack, Arthur J; Dunlea, Ann G; Murray, Richard W; D'Hondt, Steven

    2016-01-01

    Hydrogen (H2) is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium ((238)U, (235)U), thorium ((232)Th) and potassium ((40)K). To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th, and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt) concentrations (which can vary between eruptive events) and post-emplacement alteration. However, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2 production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (>10 Ma) basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may support as

  17. Radiolytic Hydrogen Production in the Subseafloor Basaltic Aquifer

    PubMed Central

    Dzaugis, Mary E.; Spivack, Arthur J.; Dunlea, Ann G.; Murray, Richard W.; D’Hondt, Steven

    2016-01-01

    Hydrogen (H2) is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium (238U, 235U), thorium (232Th) and potassium (40K). To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th, and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt) concentrations (which can vary between eruptive events) and post-emplacement alteration. However, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2 production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (>10 Ma) basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may support as many as

  18. Shocked basalt from Lonar Impact Crater, India, and experimental analogues

    NASA Technical Reports Server (NTRS)

    Kieffer, S. W.; Schaal, R. B.; Gibbons, R.; Horz, F.; Milton, D. J.; Dube, A.

    1976-01-01

    Samples of Lonar basalts were experimentally shocked in vacuum to pressures between 200 and 650 kbar by a 20 mm, high-velocity gun. Plagioclase and palagonite in experimentally shocked samples show deformation similar to that in the naturally shocked rocks, but pyroxene does not show optically resolvable edge melting. It is estimated that pressures in excess of 800-1000 kbar are required for the formation of totally shock-melted rocks from nonporous basalt.

  19. The Search for Interstellar Sulfide Grains

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Messenger, Scott

    2010-01-01

    The lifecycle of sulfur in the galaxy is poorly understood. Fe-sulfide grains are abundant in early solar system materials (e.g. meteorites and comets) and S is highly depleted from the gas phase in cold, dense molecular cloud environments. In stark contrast, sulfur is essentially undepleted from the gas phase in the diffuse interstellar medium, indicating that little sulfur is incorporated into solid grains in this environment. It is widely believed that sulfur is not a component of interstellar dust grains. This is a rather puzzling observation unless Fe-sulfides are not produced in significant quantities in stellar outflows, or their lifetime in the ISM is very short due to rapid destruction. Fe sulfide grains are ubiquitous in cometary samples where they are the dominant host of sulfur. The Fe-sulfides (primarily pyrrhotite; Fe(1-x)S) are common, both as discrete 0.5-10 micron-sized grains and as fine (5-10 nm) nanophase inclusions within amorphous silicate grains. Cometary dust particles contain high abundances of well-preserved presolar silicates and organic matter and we have suggested that they should contain presolar sulfides as well. This hypothesis is supported by the observation of abundant Fe-sulfides grains in dust around pre- and post-main sequence stars inferred from astronomical spectra showing a broad 23 micron IR feature due to FeS. Fe-sulfide grains also occur as inclusions in bona fide circumstellar amorphous silicate grains and as inclusions within deuterium-rich organic matter in cometary dust samples. Our irradiation experiments show that FeS is far more resistant to radiation damage than silicates. Consequently, we expect that Fe sulfide stardust should be as abundant as silicate stardust in solar system materials.

  20. Upper critical field of copper molybdenum sulfide

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Woollam, J. A.

    1978-01-01

    The upper critical field of sintered and sputtered copper molybdenum sulfide Cu(x)Mo6S8 was measured and found to exceed the Werthamer, Helfand, and Hohenberg (1966) value for a type II superconductor characterized by dirty limit, weak isotropic electron phonon coupling, and no paramagnetic limiting. It is suggested that the enhancement results from anisotropy or clean limit or both. Other ternary molybdenum sulfides appear to show similar anomalies.

  1. Modes of emplacement of basalt terrains and an analysis of mare volcanism in the Orientale Basin

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1976-01-01

    Three distinctive types of basalt terrains can be recognized on earth on the basis of surface morphology: flood basalts, shield basalts, and plains basalts, each of which reflects unique styles of eruption and modes of emplacement. Two of these, flood basalts and plains basalts, appear to be important in the emplacement of mare basalts on the moon. Using surface features as identifying criteria, mare units in the Orientale Basin were examined and the following emplacement sequence was derived: (1) initial emplacement of impact melt in the basin center, (2) eruption of flood-type basalts in the basin center and approximately concurrent emplacement of plains type basalts in Lacus Veris, and (3) emplacement of plains type basalts in Lacus Autumni

  2. The source and longevity of sulfur in an Icelandic flood basalt eruption plume

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Edmonds, Marie; Mather, Tamsin; Schmidt, Anja; Hartley, Margaret; Oppenheimer, Clive; Pope, Francis; Donovan, Amy; Sigmarsson, Olgeir; Maclennan, John; Shorttle, Oliver; Francis, Peter; Bergsson, Baldur; Barsotti, Sara; Thordarson, Thorvaldur; Bali, Eniko; Keller, Nicole; Stefansson, Andri

    2015-04-01

    The Holuhraun fissure eruption (Bárðarbunga volcanic system, central Iceland) has been ongoing since 31 August 2014 and is now the largest in Europe since the 1783-84 Laki event. For the first time in the modern age we have the opportunity to study at first hand the environmental impact of a flood basalt fissure eruption (>1 km3 lava). Flood basalt eruptions are one of the most hazardous volcanic scenarios in Iceland and have had enormous societal and economic consequences across the northern hemisphere in the past. The Laki eruption caused the deaths of >20% of the Icelandic population by environmental pollution and famine and potentially also increased European levels of mortality through air pollution by sulphur-bearing gas and aerosol. A flood basalt eruption was included in the UK National Risk Register in 2012 as one of the highest priority risks. The gas emissions from Holuhraun have been sustained since its beginning, repeatedly causing severe air pollution in populated areas in Iceland. During 18-22 September, SO2 fluxes reached 45 kt/day, a rate of outgassing rarely observed during sustained eruptions, suggesting that the sulfur loading per kg of erupted magma exceeds both that of other recent eruptions in Iceland and perhaps also other historic basaltic eruptions globally. This raises key questions regarding the origin of these prodigious quantities of sulphur. A lack of understanding of the source of this sulfur, the conversion rates of SO2 gas into aerosol, the residence times of aerosol in the plume and the dependence of these on meteorological factors is limiting our confidence in the ability of atmospheric models to forecast gas and aerosol concentrations in the near- and far-field from Icelandic flood basalt eruptions. In 2015 our group is undertaking a project funded by UK NERC urgency scheme to investigate several aspects of the sulfur budget at Holuhraun using a novel and powerful approach involving simultaneous tracking of sulfur and

  3. Effect of molybdenum plus chromium on the corrosion of iron-, nickel-, and cobalt-base alloys in basaltic lava and simulated magmatic gas at 1150/sup 0/C

    SciTech Connect

    Ehrlich, S.A.; Douglass, D.L.

    1982-06-01

    The compatibility of several binary and ternary alloys in a magma environment was studied. Binary alloys containing molybdenum and ternary alloys containing chromium and molybdenum were exposed to basaltic lava at 1150/sup 0/C for periods of 24 and 96 hours. A cover gas was used to produce oxygen and sulfur fugacities corresponding to those of the gases dissolved in basaltic melts. Three base metals were used. These included iron, nickel, and cobalt. The primary reactions in binary alloys were found to be sulfidation. Oxide scales with a spinel layer formed on ternary alloys. The synergistic effect of molybdenum and chromium additions in ternary alloys exhibited superior corrosion resistance to binary alloys which formed base-metal sulfides down grain-boundaries. Extensive analyses of the reaction products by scanning electron microscopy, X-ray energy dispersive analysis, electron microprobe analysis, and metallography are presented for each alloys. The products formed are discussed with reference to thermodynamic stability diagrams, and the reaction path concept is used to explain some of the corrosion.

  4. Testing the Origins of Basalt Fragments fro Apollo 16

    NASA Technical Reports Server (NTRS)

    Donohue, P. H.; Stevens, R. E.; Neal, C. R.; Zeigler, R. A.

    2013-01-01

    Several 2-4 mm regolith fragments of basalt from the Apollo 16 site were recently described by [1]. These included a high-Ti vitrophyric basalts (60603,10-16) and one very-low-titanium (VLT) crystalline basalt (65703,9-13). As Apollo 16 was the only highlands sample return mission distant from the maria, identification of basaltic samples at the site indicates input from remote sites via impact processes [1]. However, distinguishing between impact melt and pristine basalt can be notoriously difficult and requires significant sample material [2-6]. The crystal stratigraphy method utilizes essentially non-destructive methods to make these distinctions [7,8]. Crystal stratigraphy combines quantitative petrography in the form of crystal size distributions (CSDs) coupled with mineral geochemistry to reveal the petrogenetic history of samples. The classic CSD plot of crystal size versus population density can reveal insights on growth/cooling rates, residence times, and magma history which in turn can be used to evaluate basaltic vs impact melt origin [7-9]. Electron microprobe (EMP) and laser ablation (LA)-ICP-MS analyses of mineral phases complement textural investigations. Trace element variations document subtle changes occurring during the formation of the samples, and are key in the interpretation and preservation of this rare lunar sample collection.

  5. Thermal infrared spectroscopy and modeling of experimentally shocked basalts

    USGS Publications Warehouse

    Johnson, J. R.; Staid, M.I.; Kraft, M.D.

    2007-01-01

    New measurements of thermal infrared emission spectra (250-1400 cm-1; ???7-40 ??m) of experimentally shocked basalt and basaltic andesite (17-56 GPa) exhibit changes in spectral features with increasing pressure consistent with changes in the structure of plagioclase feldspars. Major spectral absorptions in unshocked rocks between 350-700 cm-1 (due to Si-O-Si octahedral bending vibrations) and between 1000-1250 cm-1 (due to Si-O antisymmetric stretch motions of the silica tetrahedra) transform at pressures >20-25 GPa to two broad spectral features centered near 950-1050 and 400-450 cm-1. Linear deconvolution models using spectral libraries composed of common mineral and glass spectra replicate the spectra of shocked basalt relatively well up to shock pressures of 20-25 GPa, above which model errors increase substantially, coincident with the onset of diaplectic glass formation in plagioclase. Inclusion of shocked feldspar spectra in the libraries improves fits for more highly shocked basalt. However, deconvolution models of the basaltic andesite select shocked feldspar end-members even for unshocked samples, likely caused by the higher primary glass content in the basaltic andesite sample.

  6. Hotspots, basalts, and the evolution of the mantle

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1981-01-01

    It is noted that the trace element concentration patterns of continental and ocean island basalts and of mid-ocean ridge basalts are complementary. Estimates of the relative sizes of the source regions for these fundamentally different basalt types can be arrived at from the trace element enrichment-depletion patterns. Their combined volume occupies the greater part of the mantle above the 670 km discontinuity. It is pointed out that the source regions separated as a result of early mantle differentiation and crystal fractionation from the resulting melt. The mid-ocean ridge basalts source evolved from an eclogite cumulate that gave up its late-stage enriched fluids at various times to the shallower mantle and continental crust. The mid-ocean ridge basalts source is rich in garnet and clinopyroxene, while the continental and ocean island basalt source is a garnet peridotite that has experienced secondary enrichment. These relationships are found to be consistent with the evolution of a terrestrial magma ocean.

  7. Insulation from basaltic stamp sand. Final technical report

    SciTech Connect

    Williams, F. D.

    1981-04-01

    A Midwest Appropriate Technology Grant was awarded to determine the technical and economic feasibility of producing mineral-fiber insulation directly from extensive deposits of basaltic sand produced during former mining and milling operations in the Keweenaw Peninsula region of Michigan's Upper Peninsula. The amounts of local basaltic sands available and representative chemical compositions were determined. The variation of viscosity with temperature and chemical composition was estimated. Samples were melted and either pulled or blown into fiber. In all cases fiber could be made with a reasonable tensile strength to ensure usefulness. It was concluded that it was technically feasible to produce fibers from basaltic stamp sands of the Upper Peninsula of Michigan. A technical feasibility study using published data, a cost and design analysis of a basalt fiber production plant, a market survey of fiber needs, and an economic analysis for investing in a basalt fiber venture was undertaken. These studies concluded that the local production of basaltic insulation was both feasible and economically reasonable. It was suggested that the plant be located in a region of greater population density with lower utility costs. A representative one-third of these studies is included as appendices A, B, C, and D.

  8. A basalt trigger for the 1991 eruptions of Pinatubo volcano?

    USGS Publications Warehouse

    Pallister, J.S.; Hoblitt, R.P.; Reyes, A.G.

    1992-01-01

    THE eruptive products of calc-alkaline volcanos often show evidence for the mixing of basaltic and acid magmas before eruption (see, for example, refs 1, 2). These observations have led to the suggestion3 that the injection of basaltic magma into the base of a magma chamber (or the catastrophic overturn of a stably stratified chamber containing basaltic magma at its base) might trigger an eruption. Here we report evidence for the mixing of basaltic and dacitic magmas shortly before the paroxysmal eruptions of Pinatubo volcano on 15 June 1991. Andesitic scoriae erupted on 12 June contain minerals and glass with disequilibrium compositions, and are considerably more mafic than the dacitic pumices erupted on 15 June. Differences in crystal abundance and glass composition among the pumices may arise from pre-heating of the dacite magma by the underlying basaltic liquid before mixing. Degassing of this basaltic magma may also have contributed to the climatologically important sulphur dioxide emissions that accompanied the Pinatubo eruptions.

  9. Geological perspectives of metalliferous sulfides: offshore exploration in the Gorda Ridge area

    SciTech Connect

    Beauchamp, R.G.

    1984-05-01

    The Gorda Ridge is a submarine mountain range located between 86 nautical miles (160km) and 178 nautical miles (330km) off the coasts of northern California and Oregon. Preliminary results from recent investigations of samples from the Ridge suggest both low and high temperature hydrothermal activity. Sea Marc II (Sea Mapping and Remote Characterization) maps of the Gorda Ridge assist in the identification of the central rift valley, seamounts, continuous and discontinuous ridges, and ridge offsets. Volcanic samples dredged from the Gorda Ridge contain traces of sulfide minerals (e.g., pyrite, pyrrhotite, and sphalerite). Fresh volcanic glass occurred in most of the dredge samples. Other samples showed evidence of hydrothermal activity including the occurrence of geothite and nontronite. Manganese minerals todorokite and birnessite occur as encrustations over basalt. Abundant worm tubes were found in association with nontronite. Agglutinated benthic foramifera, some with tests constructed of volcanic glass, are abundant and found in a majority of dredge hauls.

  10. Leaching of metals and trace elements from sulfide-bearing coal waste in southwestern Illinois

    SciTech Connect

    Krothe, N.C.; Edkins, J.E.; Schubert, J.P.

    1980-01-01

    Metal sulfides, chiefly pyrite and minor sphalerite, associated with the Herrin (No. 6) coal member of the Pennsylvanian Carbondale Formation, have been concentrated in a coal refuse deposit in southern Illinois. Chemical, petrographic, and x-ray-diffraction data for 34 cores, show that the upper two meters of material have been leached of sulfides in the thirty years since washing operations ceased. Oxidation of pyrite has produced highly acid waters with high concentrations of iron, zinc (up to 200 parts per million) and toxic trace elements that have leached downward to a water system perched on the underlying Illinoisan glacial drift. Deep well samples in the refuse pile are more saturated with metals than are the runoff waters and shallow-well samples. Metal recovery does not appear to be economically feasible at this site.

  11. Linking hydrothermal geochemistry to organismal physiology: physiological versatility in Riftia pachyptila from sedimented and basalt-hosted vents.

    PubMed

    Robidart, Julie C; Roque, Annelys; Song, Pengfei; Girguis, Peter R

    2011-01-01

    Much of what is known regarding Riftia pachyptila physiology is based on the wealth of studies of tubeworms living at diffuse flows along the fast-spreading, basalt-hosted East Pacific Rise (EPR). These studies have collectively suggested that Riftia pachyptila and its chemoautotrophic symbionts are physiologically specialized, highly productive associations relying on hydrogen sulfide and oxygen to generate energy for carbon fixation, and the symbiont's nitrate reduction to ammonia for energy and biosynthesis. However, Riftia also flourish in sediment-hosted vents, which are markedly different in geochemistry than basalt-hosted systems. Here we present data from shipboard physiological studies and global quantitative proteomic analyses of Riftia pachyptila trophosome tissue recovered from tubeworms residing in the EPR and the Guaymas basin, a sedimented, hydrothermal vent field. We observed marked differences in symbiont nitrogen metabolism in both the respirometric and proteomic data. The proteomic data further suggest that Riftia associations in Guaymas may utilize different sulfur compounds for energy generation, may have an increased capacity for energy storage, and may play a role in degrading exogenous organic carbon. Together these data reveal that Riftia symbionts are far more physiologically plastic than previously considered, and that--contrary to previous assertions--Riftia do assimilate reduced nitrogen in some habitats. These observations raise new hypotheses regarding adaptations to the geochemical diversity of habitats occupied by Riftia, and the degree to which the environment influences symbiont physiology and evolution. PMID:21779334

  12. Chloritites of the Tocantins Group, Araguaia fold belt, central-northern Brazil: Vestiges of basaltic magmatism and metallogenetic implications

    NASA Astrophysics Data System (ADS)

    Kotschoubey, Basile; Villas, Raimundo Netuno; Aires, Benevides

    2016-08-01

    Chloritites from different localities (Arapoema, Couto Magalhães Velho, Juarina, Morro Grande, Morro do Jabuti, Morro do Pau Ferrado, Morro do Salto, Serra do Jacu, Serra do Quatipuru, Serra do Tapa, Serrinha) of the Araguaia fold belt, Tocantins geotectonic province, central-northern Brazil, have been investigated. Based on field work and petrographic, diffractometric, geochemical and mineral chemistry data, these rocks, commonly associated with metacherts and banded iron formations, have been interpreted as products of ocean-floor exhalative-hydrothermal activity on MORB basalts. Distribution patterns of rare earth elements and diagrams of relatively immobile components in the hydrothermal environment highlight not only the genetic link between the chloritites and the basaltic rocks that occur in the region (Serra do Tapa and Morro do Agostinho), but also some peculiar characteristics of the submarine environment. The rock association and anomalous contents of Cu, Zn, Ni, As, and Au are suggestive that the region was favorable to the formation of volcanogenic massive sulfide deposits, what makes it a potential target for mineral exploration programs.

  13. Absolute magnetization of the seafloor at a basalt-hosted hydrothermal site: Insights from a deep-sea submersible survey

    NASA Astrophysics Data System (ADS)

    Szitkar, Florent; Dyment, Jérôme; Fouquet, Yves; Choi, Yujin; Honsho, Chie

    2015-02-01

    The analysis of high-resolution vector magnetic data acquired by deep-sea submersibles (DSSs) requires the development of specific approaches adapted to their uneven tracks. We present a method that takes advantage of (1) the varying altitude of the DSS above the seafloor and (2) high-resolution multibeam bathymetric data acquired separately, at higher altitude, by an Autonomous Underwater Vehicle, to estimate the absolute magnetization intensity and the magnetic polarity of the shallow subseafloor along the DSS path. We apply this method to data collected by DSS Nautile on a small active basalt-hosted hydrothermal site. The site is associated with a lack of magnetization, in agreement with previous findings at the same kind of sites: the contrast between nonmagnetic sulfide deposits/stockwork zone and strongly magnetized basalt is sufficient to explain the magnetic signal observed at such a low altitude. Both normal and reversed polarities are observed in the lava flows surrounding the site, suggesting complex history of accumulating volcanic flows.

  14. Linking hydrothermal geochemistry to organismal physiology: physiological versatility in Riftia pachyptila from sedimented and basalt-hosted vents.

    PubMed

    Robidart, Julie C; Roque, Annelys; Song, Pengfei; Girguis, Peter R

    2011-01-01

    Much of what is known regarding Riftia pachyptila physiology is based on the wealth of studies of tubeworms living at diffuse flows along the fast-spreading, basalt-hosted East Pacific Rise (EPR). These studies have collectively suggested that Riftia pachyptila and its chemoautotrophic symbionts are physiologically specialized, highly productive associations relying on hydrogen sulfide and oxygen to generate energy for carbon fixation, and the symbiont's nitrate reduction to ammonia for energy and biosynthesis. However, Riftia also flourish in sediment-hosted vents, which are markedly different in geochemistry than basalt-hosted systems. Here we present data from shipboard physiological studies and global quantitative proteomic analyses of Riftia pachyptila trophosome tissue recovered from tubeworms residing in the EPR and the Guaymas basin, a sedimented, hydrothermal vent field. We observed marked differences in symbiont nitrogen metabolism in both the respirometric and proteomic data. The proteomic data further suggest that Riftia associations in Guaymas may utilize different sulfur compounds for energy generation, may have an increased capacity for energy storage, and may play a role in degrading exogenous organic carbon. Together these data reveal that Riftia symbionts are far more physiologically plastic than previously considered, and that--contrary to previous assertions--Riftia do assimilate reduced nitrogen in some habitats. These observations raise new hypotheses regarding adaptations to the geochemical diversity of habitats occupied by Riftia, and the degree to which the environment influences symbiont physiology and evolution.

  15. The Axum-Adwa basalt-trachyte complex: a late magmatic activity at the periphery of the Afar plume

    NASA Astrophysics Data System (ADS)

    Natali, C.; Beccaluva, L.; Bianchini, G.; Siena, F.

    2013-08-01

    The Axum-Adwa igneous complex consists of a basalt-trachyte (syenite) suite emplaced at the northern periphery of the Ethiopian plateau, after the paroxysmal eruption of the Oligocene (ca 30 Ma) continental flood basalts (CFB), which is related to the Afar plume activity. 40Ar/39Ar and K-Ar ages, carried out for the first time on felsic and basaltic rocks, constrain the magmatic age of the greater part of the complex around Axum to 19-15 Ma, whereas trachytic lavas from volcanic centres NE of Adwa are dated ca 27 Ma. The felsic compositions straddle the critical SiO2-saturation boundary, ranging from normative quartz trachyte lavas east of Adwa to normative (and modal) nepheline syenite subvolcanic domes (the obelisks stones of ancient axumites) around Axum. Petrogenetic modelling based on rock chemical data and phase equilibria calculations by PELE (Boudreau 1999) shows that low-pressure fractional crystallization processes, starting from mildly alkaline- and alkaline basalts comparable to those present in the complex, could generate SiO2-saturated trachytes and SiO2-undersaturated syenites, respectively, which correspond to residual liquid fractions of 17 and 10 %. The observed differentiation processes are consistent with the development of rifting events and formation of shallow magma chambers plausibly located between displaced (tilted) crustal blocks that favoured trapping of basaltic parental magmas and their fractionation to felsic differentiates. In syenitic domes, late- to post-magmatic processes are sometimes evidenced by secondary mineral associations (e.g. Bete Giorgis dome) which overprint the magmatic parageneses, and mainly induce additional nepheline and sodic pyroxene neo-crystallization. These metasomatic reactions were promoted by the circulation of Na-Cl-rich deuteric fluids (600-400 °C), as indicated by mineral and bulk rock chemical budgets as well as by δ18O analyses on mineral separates. The occurrence of this magmatism post-dating the

  16. 87Sr/86Sr ratios in basalts from islands in the Indian Ocean

    USGS Publications Warehouse

    Hedge, C.E.; Watkins, N.D.; Hildreth, R.A.; Doering, W.P.

    1973-01-01

    87Sr/86Sr ratios of basalts from islands in the Indian Ocean (0.7040) are higher than those of basalts dredged from the Mid-Indian Ocean Ridge (0.7034). The sources of the island basalts have apparently not been in equilibrium with the source of the ridge basalts for roughly 109 years. Both ridge and island basalts in the Indian Ocean are higher in 87Sr/86Sr than are rocks from similar settings in the eastern Pacific. ?? 1973.

  17. Importance of lunar granite and KREEP in very high potassium (VHK) basalt petrogenesis

    NASA Technical Reports Server (NTRS)

    Neal, Clive R.; Taylor, Lawrence A.; Lindstrom, Marilyn M.

    1988-01-01

    Analysis of five very high potassium (VHK) basalts from Apollo 14 breccia 14303 shows the presence of a KREEP component. An assimilation and fractional crystallization model is presented to describe the basalt evolution. The influence of granite assimilation on the basalt evolution is discussed. The presence of VHK basalts containing only a granite signature and those with both granite and KREEP signatures suggests that there are at least two different VHK basalt flows at the Apollo 14 site.

  18. The Plumbing System of a Highly Explosive Basaltic Volcano: Sunset Crater, AZ

    NASA Astrophysics Data System (ADS)

    Allison, C. M.; Roggensack, K.; Clarke, A. B.

    2015-12-01

    We seek to better understand highly explosive basaltic eruptions with specific focus on magmatic volatile solubility in alkali basalts and the magma plumbing system. Sunset Crater, an alkali basalt (~3.7 wt.% alkalis) scoria cone volcano, erupted explosively in 1085 AD. We analyzed 125 primary melt inclusions (MIs) from Sunset Crater tephra deposited by 2 subplinian phases and 1 Strombolian explosion to compare magma volatiles and storage conditions. We picked rapidly quenched free olivine crystals and selected large volume MIs (50-180 μm) located toward crystal cores. MIs are faceted and exhibit little major element composition variability with minor post entrapment crystallization (2-10%). MIs are relatively dry but CO2-rich. Water content varies from 0.4 wt.% to 1.5 wt.% while carbon dioxide abundance ranges between 1,150 ppm and 3,250 ppm. Most MIs contain >1 wt.% H2O and >2,150 ppm CO2. All observed MIs contain a vapor bubble, so we are evaluating MI vapor bubbles with Raman spectroscopy and re-homogenization experiments to determine the full volatile budget. Because knowledge of volatile solubility is critical to accurately interpret results from MI analyses, we measured H2O-CO2 solubility in the Sunset Crater bulk composition. Fluid-saturated experiments at 4 and 6 kbar indicate shallower entrapment pressures for these MIs than values calculated for this composition using existing models. Assuming fluid saturation, MIs record depths from 6 km to 14 km, including groupings suggesting two pauses for longer-term storage at ~6 km and ~10.5 km. We do not observe any significant differences in MIs from phases exhibiting different eruptive styles, suggesting that while a high CO2 content may drive rapid magma ascent and be partly responsible for highly explosive eruptions, shallower processes may govern the final eruptive character. To track shallow processes during magma ascent from depth of MI-entrapment up to the surface, we are examining MI re-entrants.

  19. Icelandic basaltic geothermal field: A natural analog for nuclear waste isolation in basalt

    SciTech Connect

    Ulmer, G.C.; Grandstaff, D.E. . Dept. of Geology)

    1984-11-21

    Analog studies of Icelandic geothermal fields have shown that the design of nuclear waste repositories in basalt can benefit by comparison to the data base already available from the development of these geothermal fields. A high degree of similarity exists between these two systems: their petrology, groundwater geochemistry, mineral solubilities, hydrologic parameters, temperature ranges, water-rock redox equilibria, hydrothermal pH values, and secondary mineralogies all show considerable overlap in the range of values. The experimentally-simulated hydrothermal studies of the basaltic nuclear waste repository rocks have, at this time, produced a data base that receives a strong confirmation from the Icelandic analog. Furthermore, the Icelandic analog should eventually be employed to extrapolate into higher and lower temperatures, into longer time-base chemical comparisons, and into more realistic mineral deposition studies, than have been possible in the laboratory evaluations of the nuclear waste repository designs. This eventual use of the Icelandic analog will require cooperative work with the Icelandic Geological Survey. 46 refs., 4 figs., 2 tabs.

  20. Strength and durability of basalt fiber and basalt-fiber cement composites

    SciTech Connect

    Vedagiri, V.

    1987-01-01

    Basalt fibers melt drawn from naturally occurring igneous rock in an inert atmosphere of helium, argon or nitrogen show significantly improved mean strength (3.7 GPa). Weibull analysis of fiber strengths at different gage lengths indicates a high-strength population governing strength below 6.5-mm gage and a low-strength population at higher gage lengths. The durability of the basalt-cement composites was studied by conducting tensile and flexural tests, after water immersion at different temperatures for different times. By measuring the mirror-zone radius on the fiber surfaces in fractured composite specimens, the retention of fiber strength within the composite was also measured. The chemical and microstructural changes in the fiber-matrix interphase region were investigated by using electron probe microanalysis (EPMA). The fiber-matrix bond strength was evaluated by investigating multiple crack failure modes of composite specimens. The results indicate that although the strength values are comparable to other fiber systems, the precipitation of calcium hydroxide at the interface and the degradation of the fiber in the alkaline matrix decrease the strength of the composites, over extended period of time.

  1. Biogeography and biodiversity in sulfide structures of active and inactive vents at deep-sea hydrothermal fields of the Southern Mariana Trough.

    PubMed

    Kato, Shingo; Takano, Yoshinori; Kakegawa, Takeshi; Oba, Hironori; Inoue, Kazuhiko; Kobayashi, Chiyori; Utsumi, Motoo; Marumo, Katsumi; Kobayashi, Kensei; Ito, Yuki; Ishibashi, Jun-ichiro; Yamagishi, Akihiko

    2010-05-01

    The abundance, diversity, activity, and composition of microbial communities in sulfide structures both of active and inactive vents were investigated by culture-independent methods. These sulfide structures were collected at four hydrothermal fields, both on- and off-axis of the back-arc spreading center of the Southern Mariana Trough. The microbial abundance and activity in the samples were determined by analyzing total organic content, enzymatic activity, and copy number of the 16S rRNA gene. To assess the diversity and composition of the microbial communities, 16S rRNA gene clone libraries including bacterial and archaeal phylotypes were constructed from the sulfide structures. Despite the differences in the geological settings among the sampling points, phylotypes related to the Epsilonproteobacteria and cultured hyperthermophilic archaea were abundant in the libraries from the samples of active vents. In contrast, the relative abundance of these phylotypes was extremely low in the libraries from the samples of inactive vents. These results suggest that the composition of microbial communities within sulfide structures dramatically changes depending on the degree of hydrothermal activity, which was supported by statistical analyses. Comparative analyses suggest that the abundance, activity and diversity of microbial communities within sulfide structures of inactive vents are likely to be comparable to or higher than those in active vent structures, even though the microbial community composition is different between these two types of vents. The microbial community compositions in the sulfide structures of inactive vents were similar to those in seafloor basaltic rocks rather than those in marine sediments or the sulfide structures of active vents, suggesting that the microbial community compositions on the seafloor may be constrained by the available energy sources. Our findings provide helpful information for understanding the biogeography, biodiversity and

  2. Biogeography and biodiversity in sulfide structures of active and inactive vents at deep-sea hydrothermal fields of the Southern Mariana Trough.

    PubMed

    Kato, Shingo; Takano, Yoshinori; Kakegawa, Takeshi; Oba, Hironori; Inoue, Kazuhiko; Kobayashi, Chiyori; Utsumi, Motoo; Marumo, Katsumi; Kobayashi, Kensei; Ito, Yuki; Ishibashi, Jun-ichiro; Yamagishi, Akihiko

    2010-05-01

    The abundance, diversity, activity, and composition of microbial communities in sulfide structures both of active and inactive vents were investigated by culture-independent methods. These sulfide structures were collected at four hydrothermal fields, both on- and off-axis of the back-arc spreading center of the Southern Mariana Trough. The microbial abundance and activity in the samples were determined by analyzing total organic content, enzymatic activity, and copy number of the 16S rRNA gene. To assess the diversity and composition of the microbial communities, 16S rRNA gene clone libraries including bacterial and archaeal phylotypes were constructed from the sulfide structures. Despite the differences in the geological settings among the sampling points, phylotypes related to the Epsilonproteobacteria and cultured hyperthermophilic archaea were abundant in the libraries from the samples of active vents. In contrast, the relative abundance of these phylotypes was extremely low in the libraries from the samples of inactive vents. These results suggest that the composition of microbial communities within sulfide structures dramatically changes depending on the degree of hydrothermal activity, which was supported by statistical analyses. Comparative analyses suggest that the abundance, activity and diversity of microbial communities within sulfide structures of inactive vents are likely to be comparable to or higher than those in active vent structures, even though the microbial community composition is different between these two types of vents. The microbial community compositions in the sulfide structures of inactive vents were similar to those in seafloor basaltic rocks rather than those in marine sediments or the sulfide structures of active vents, suggesting that the microbial community compositions on the seafloor may be constrained by the available energy sources. Our findings provide helpful information for understanding the biogeography, biodiversity and

  3. Hydrogen sulfide and translational medicine

    PubMed Central

    Guo, Wei; Cheng, Ze-yu; Zhu, Yi-zhun

    2013-01-01

    Hydrogen sulfide (H2S) along with carbon monoxide and nitric oxide is an important signaling molecule that has undergone large numbers of fundamental investigations. H2S is involved in various physiological activities associated with the regulation of homeostasis, vascular contractility, pro- and anti-inflammatory activities, as well as pro- and anti-apoptotic activities etc. However, the actions of H2S are influenced by its concentration, reaction time, and cell/disease types. Therefore, H2S is a signaling molecule without definite effect. The use of existing H2S donors is limited because of the instant release and short lifetime of H2S. Thus, translational medicine involving the sustained and controlled release of H2S is of great value for both scientific and clinical uses. H2S donation can be manipulated by different ways, including where H2S is given, how H2S is donated, or the specific structures of H2S-releasing drugs and H2S donor molecules. This review briefly summarizes recent progress in research on the physiological and pathological functions of H2S and H2S-releasing drugs, and suggests hope for future investigations. PMID:24096643

  4. Hydrogen Sulfide as a Gasotransmitter

    PubMed Central

    Gadalla, Moataz M.; Snyder, Solomon H.

    2010-01-01

    Nitric oxide (NO) and carbon monoxide (CO) are well established as messenger molecules throughout the body, gasotransmitters, based on striking alterations in mice lacking the appropriate biosynthetic enzymes. Hydrogen sulfide (H2S) is even more chemically reactive, but till recently there was little definitive evidence for its physiologic formation. Cystathionine β-synthase (CBS, EC 4.2.1.22), and Cystathionine γ-lyase (CSE; EC 4.4.1.1), also known as cytathionase, can generate H2S from cyst(e)ine. Very recent studies with mice lacking these enzymes have established that CSE is responsible for H2S formation in the periphery, while in the brain CBS is the biosynthetic enzyme. Endothelial-derived relaxing factor (EDRF) activity is reduced 80% in the mesenteric artery of mice with deletion of CSE, establishing H2S as a major physiologic EDRF. H2S appears to signal predominantly by S-sulfhydrating cysteines in its target proteins, analogous to S-nitrosylation by NO. Whereas S-nitrosylation typically inhibits enzymes, S-sulfhydration activates them. S-nitrosylation basally affects 1–2% of its target proteins, while 10–25% of H2S target proteins are S-sulfhydrated. In summary, H2S appears to be a physiologic gasotransmitter of comparable importance to NO and CO. PMID:20067586

  5. Helium Saturation of Liquid Propellants

    NASA Technical Reports Server (NTRS)

    Yavrouian, A. H.; Moran, Clifford M.

    1990-01-01

    The research is in three areas which are: (1) techniques were devised for achieving the required levels of helium (He) saturation in liquid propellants (limited to monomethylhydrazine (MMH) and nitrogen tetroxide (NTO)); (2) the values were evaluated for equilibrium solubilities of He in liquid propellants as currently used in the industry; and (3) the He dissolved in liquid propellants were accurately measured. Conclusions drawn from these studies include: (1) Techniques for dissolving He in liquid propellants depending upon the capabilities of the testing facility (Verification of the quantity of gas dissolved is essential); (2) Until greater accuracy is obtained, the equilibrium solubility values of He in MMH and NTO as cited in the Air Force Propellant Handbooks should be accepted as standard (There are still enough uncertainties in the He saturation values to warrant further basic experimental studies); and (3) The manometric measurement of gas volume from a frozen sample of propellant should be the accepted method for gas analysis.

  6. Criteria for saturated magnetization loop

    NASA Astrophysics Data System (ADS)

    Harres, A.; Mikhov, M.; Skumryev, V.; Andrade, A. M. H. de; Schmidt, J. E.; Geshev, J.

    2016-03-01

    Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe3O4 and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one.

  7. Saturation of the turbulent dynamo.

    PubMed

    Schober, J; Schleicher, D R G; Federrath, C; Bovino, S; Klessen, R S

    2015-08-01

    The origin of strong magnetic fields in the Universe can be explained by amplifying weak seed fields via turbulent motions on small spatial scales and subsequently transporting the magnetic energy to larger scales. This process is known as the turbulent dynamo and depends on the properties of turbulence, i.e., on the hydrodynamical Reynolds number and the compressibility of the gas, and on the magnetic diffusivity. While we know the growth rate of the magnetic energy in the linear regime, the saturation level, i.e., the ratio of magnetic energy to turbulent kinetic energy that can be reached, is not known from analytical calculations. In this paper we present a scale-dependent saturation model based on an effective turbulent resistivity which is determined by the turnover time scale of turbulent eddies and the magnetic energy density. The magnetic resistivity increases compared to the Spitzer value and the effective scale on which the magnetic energy spectrum is at its maximum moves to larger spatial scales. This process ends when the peak reaches a characteristic wave number k☆ which is determined by the critical magnetic Reynolds number. The saturation level of the dynamo also depends on the type of turbulence and differs for the limits of large and small magnetic Prandtl numbers Pm. With our model we find saturation levels between 43.8% and 1.3% for Pm≫1 and between 2.43% and 0.135% for Pm≪1, where the higher values refer to incompressible turbulence and the lower ones to highly compressible turbulence. PMID:26382506

  8. Saturation of the turbulent dynamo.

    PubMed

    Schober, J; Schleicher, D R G; Federrath, C; Bovino, S; Klessen, R S

    2015-08-01

    The origin of strong magnetic fields in the Universe can be explained by amplifying weak seed fields via turbulent motions on small spatial scales and subsequently transporting the magnetic energy to larger scales. This process is known as the turbulent dynamo and depends on the properties of turbulence, i.e., on the hydrodynamical Reynolds number and the compressibility of the gas, and on the magnetic diffusivity. While we know the growth rate of the magnetic energy in the linear regime, the saturation level, i.e., the ratio of magnetic energy to turbulent kinetic energy that can be reached, is not known from analytical calculations. In this paper we present a scale-dependent saturation model based on an effective turbulent resistivity which is determined by the turnover time scale of turbulent eddies and the magnetic energy density. The magnetic resistivity increases compared to the Spitzer value and the effective scale on which the magnetic energy spectrum is at its maximum moves to larger spatial scales. This process ends when the peak reaches a characteristic wave number k☆ which is determined by the critical magnetic Reynolds number. The saturation level of the dynamo also depends on the type of turbulence and differs for the limits of large and small magnetic Prandtl numbers Pm. With our model we find saturation levels between 43.8% and 1.3% for Pm≫1 and between 2.43% and 0.135% for Pm≪1, where the higher values refer to incompressible turbulence and the lower ones to highly compressible turbulence.

  9. Vapor segregation and loss in basaltic melts

    USGS Publications Warehouse

    Edmonds, M.; Gerlach, T.M.

    2007-01-01

    Measurements of volcanic gases at Pu'u'O??'o??, Kilauea Volcano, Hawai'i, reveal distinct degassing regimes with respect to vapor segregation and loss during effusive activity in 2004-2005. Three styles of vapor loss are distinguished by the chemical character of the emitted volcanic gases, measured by open path Fourier transform infrared spectroscopy: 1 persistent continuous gas emission, 2 gas piston events, and 3 lava spattering. Persistent continuous gas emission is associated with magma ascent and degassing beneath the crater vents, then eruption of the degassed magma from flank vents. Gas piston events are the result of static gas accumulation at depths of 400-900 m beneath Pu'u'O??'o??. A CO2-rich gas slug travels up the conduit at a few meters per second, displacing magma as it expands. Lava spattering occurs due to dynamic bubble coalescence in a column of relatively stagnant magma. The Large gas bubbles are H2O rich and are generated by open-system degassing at depths of <150 m. Static gas accumulation and dynamic bubble coalescence are both manifestations of vapor segregation in basaltic melts, but their implications differ. Accumulation and segregation of CO2-rich vapor at depth does not deplete the melt of H2O (required to drive lava fountains near to the surface) and therefore gas piston events can occur interspersed with lava fountaining activity. Lava spattering, however, efficiently strips H2O-rich vapor from magma beneath the crater vents; the magma must then erupt effusively from vents on the flank of the cone. ?? 2007 The Geological Society of America.

  10. Geomechanical rock properties of a basaltic volcano

    NASA Astrophysics Data System (ADS)

    Schaefer, Lauren; Kendrick, Jackie; Lavallée, Yan; Oommen, Thomas; Chigna, Gustavo

    2015-06-01

    In volcanic regions, reliable estimates of mechanical properties for specific volcanic events such as cyclic inflation-deflation cycles by magmatic intrusions, thermal stressing, and high temperatures are crucial for building accurate models of volcanic phenomena. This study focuses on the challenge of characterizing volcanic materials for the numerical analyses of such events. To do this, we evaluated the physical (porosity, permeability) and mechanical (strength) properties of basaltic rocks at Pacaya Volcano (Guatemala) through a variety of laboratory experiments, including: room temperature, high temperature (935 °C), and cyclically-loaded uniaxial compressive strength tests on as-collected and thermally-treated rock samples. Knowledge of the material response to such varied stressing conditions is necessary to analyze potential hazards at Pacaya, whose persistent activity has led to 13 evacuations of towns near the volcano since 1987. The rocks show a non-linear relationship between permeability and porosity, which relates to the importance of the crack network connecting the vesicles in these rocks. Here we show that strength not only decreases with porosity and permeability, but also with prolonged stressing (i.e., at lower strain rates) and upon cooling. Complimentary tests in which cyclic episodes of thermal or load stressing showed no systematic weakening of the material on the scale of our experiments. Most importantly, we show the extremely heterogeneous nature of volcanic edifices that arise from differences in porosity and permeability of the local lithologies, the limited lateral extent of lava flows, and the scars of previous collapse events. Input of these process-specific rock behaviors into slope stability and deformation models can change the resultant hazard analysis. We anticipate that an increased parameterization of rock properties will improve mitigation power.

  11. Exploration of a Subsurface Biosphere in a Volcanic Massive Sulfide: Results of the Mars Analog Rio Tinto Drilling Experiment

    NASA Astrophysics Data System (ADS)

    Stoker, C. R.; Stevens, T.; Amils, R.; Fernandez, D.

    2005-12-01

    Biological systems on Earth require three key ingredients-- liquid water, an energy source, and a carbon source, that are found in very few extraterrestrial environments. Previous examples of independent subsurface ecosystems have been found only in basalt aquifers. Such lithotrophic microbial ecosystems (LME) have been proposed as models for steps in the early evolution of Earth's biosphere and for potential biospheres on other planets where the surface is uninhabitable, such as Mars and Europa.. The Mars Analog Rio Tinto Experiment (MARTE) has searched in a volcanic massive sulfide deposit in Rio Tinto Spain for a subsurface biosphere capable of living without sunlight or oxygen and found a subsurface ecosystem driven by the weathering of the massive sulfide deposit (VMS) in which the rock matrix provides sufficient resources to support microbial metabolism, including the vigorous production of H2 by water-rock interactions. Microbial production of methane and sulfate occurred in the sulfide orebody and microbial production of methane and hydrogen sulfide continued in an anoxic plume downgradient from the sulfide ore. Organic carbon concentrations in the parent rock were too low to support microbes. The Rio Tinto system thus represents a new type of subsurface ecosystem with strong relevance for exobiological studies. Commercial drilling was used to reach the aquifer system at 100 m depth and conventional laboratory techniques were used to identify and characterize the biosphere. Then, the life search strategy that led to successful identification of this biosphere was applied to the development of a robotic drilling, core handling, inspection, subsampling, and life detection system built on a prototype planetary lander that was deployed in Rio Tinto Spain in September 2005 to test the capability of a robotic drilling system to search for subsurface life. A remote science team directed the simulation and analyzed the data from the MARTE robotic drill. The results

  12. Saturating the holographic entropy bound

    SciTech Connect

    Bousso, Raphael; Freivogel, Ben; Leichenauer, Stefan

    2010-10-15

    The covariant entropy bound states that the entropy, S, of matter on a light sheet cannot exceed a quarter of its initial area, A, in Planck units. The gravitational entropy of black holes saturates this inequality. The entropy of matter systems, however, falls short of saturating the bound in known examples. This puzzling gap has led to speculation that a much stronger bound, S < or approx. A{sup 3/4}, may hold true. In this note, we exhibit light sheets whose entropy exceeds A{sup 3/4} by arbitrarily large factors. In open Friedmann-Robertson-Walker universes, such light sheets contain the entropy visible in the sky; in the limit of early curvature domination, the covariant bound can be saturated but not violated. As a corollary, we find that the maximum observable matter and radiation entropy in universes with positive (negative) cosmological constant is of order {Lambda}{sup -1} ({Lambda}{sup -2}), and not |{Lambda}|{sup -3/4} as had hitherto been believed. Our results strengthen the evidence for the covariant entropy bound, while showing that the stronger bound S < or approx. A{sup 3/4} is not universally valid. We conjecture that the stronger bound does hold for static, weakly gravitating systems.

  13. NEAR-CONTINUOUS MEASUREMENT OF HYDROGEN SULFIDE AND CARBONYL SULFIDE BY AN AUTOMATIC GAS CHROMATOGRAPH

    EPA Science Inventory

    An automatic gas chromatograph with a flame photometric detector that samples and analyzes hydrogen sulfide and carbonyl sulfide at 30-s intervals is described. Temperature programming was used to elute trace amounts of carbon disulfide present in each injection from a Supelpak-S...

  14. Noril'sk/Siberian plateau basalts and Bahama hot spot: Impact triggered?

    NASA Technical Reports Server (NTRS)

    Deitz, R. S.; Mchone, J. F.

    1992-01-01

    Twenty-eight years after one of us argued that Sudbury was an astrobleme, this interpretation has only recently attained wide acceptance; not so for the view that the Sudbury Cu/Ni sulfide ores are cosmogenic. Other research has provided the triggering of plateau basalts by super-large impacts a modicum of respectability. The recent apparent successful tying in of the K/T extinctions to the Chicxulub astrobleme in the Yucatan encourages the search for an impact event that may have caused the other two major post-Paleozoic extinctions (P/Tr, Tr/J). This gives us heart to offer two further outrageous hypotheses. The cosmogenic concept for the Sudbury ore deposite remains viable because it is giant, nonultramafic, and unique (except for Noril'sk). The Triassic/Jurassic boundary catastrophic extinctions have been attributed to the Manicouagan asteroidal impact, but recent radiometric dating indicates these events are diachronous (Manicouagan astrobleme 212 +/- 2 Ma and Tr/J boundary 200 Ma).

  15. Space-Time-Isotopic Trends of Snake River Plain Basalts

    NASA Astrophysics Data System (ADS)

    Jean, M. M.; Hanan, B. B.; Shervais, J. W.

    2010-12-01

    The Snake River Plain (SRP) volcanic province is an 800 km track of basalt extending from the Owyhee Plateau to its current terminus, the Yellowstone Plateau. It is one of several late-Tertiary magmatic terranes that also include the Cascades magmatic arc, the Columbia River basalts, and the Oregon Plateau basalts; all of which are adjacent to the Basin and Range Province extensional system (Hughes and McCurry, 2002). This province represents the track of the Yellowstone plume and consists of basalt that is compositionally similar to ocean-island basalt. This basalt overlies a series of rhyolitic eruptive centers (overlapping caldera complexes, ignimbrites, and caldera-filling eruptions) that signal the arrival of the plume head (Christiansen, 2001) and herald the onset of plume-related rhyolitic and basaltic volcanism (Pierce et al., 2002). Observed within the SRP are two basalt types: the dominant low-K olivine tholeiites and less common high-K alkaline basalts. We report new Sr-, Nd-, and Pb-isotopic analyses of these two basalt types from all three SRP provinces: eastern, central, and western. Low-K tholeiites are enriched in 143Nd/144Nd and 86Sr/87Sr and forms a quasi-linear array in Pb-isotope space, along with Craters of the Moon and eastern SRP basalts. High-K lavas are found largely in the western plain, and have a uniquely different isotopic signature. They are depleted in 143Nd/144Nd and 86Sr/87Sr, relative to the low-K tholeiites, and plot closer to the BSE component of Zindler and Hart (1986). They also share the same Pb-isotopic space with high-K basalts from Smith Prairie (Boise River Group 2 of Vetter and Shervais, 1992). One low-K tholeiite - Eureka North, plots with these high alkali basalts. Mass balance models have demonstrated an increasing plume component from the Yellowstone caldera in the east to the craton edge in the west. The lavas analyzed in this study conform remarkably to this model. The mass fraction of plume component in western

  16. Effectiveness of various cover scenarios on the rate of sulfide oxidation of mine tailings

    NASA Astrophysics Data System (ADS)

    Romano, Connie G.; Ulrich Mayer, K.; Jones, David R.; Ellerbroek, David A.; Blowes, David W.

    2003-02-01

    Long term environmentally sound disposal of the millions of tons of mining residue is a serious challenge to the international mining industry. This paper evaluates, through a numerical investigation, the potential performance of desulfurized tailings as a cover material for the reduction of acidic drainage from sulfidic tailings. This evaluation is facilitated through a comparison of various cover types as decommissioning options. The cover types considered consist of a desulfurized tailings material cover exposed to ambient climate conditions, a water cover (flooded tailings), and a combination cover type. As part of the evaluation of cover performances, the effect of climatic variability on the potential rate of sulfide oxidation in tailings with an open ground surface, was also assessed. The numerical analysis was conducted using the model PYROX, which was modified to allow for variably-saturated conditions, time varying moisture contents, and to account for the temperature dependence of Henry's law and gas diffusion. In the case study presented here, the benign cover material consists of a low sulfide waste stream (cassiterite float tails, CFT), a by-product of the production of tin concentrate (cassiterite, SnO 2). Modelling results after a simulation period of 100 years indicate that a water cover alone or an exposed CFT cover alone are both less effective options than the combined cover type. A water cover alone leads to a reduction of approximately 99.1%, in the oxidation rate relative to uncovered tailings while the combined cover type results in the lowest potential extent of sulfide oxidation after mine closure-an approximately 99.8% reduction. Importantly, a CFT cover exposed to ambient environmental conditions can still substantially reduce the sulfide oxidation rate, by approximately 75-82% over a 100-year time period, relative to uncovered tailings. Variability in precipitation (and hence percent saturation of the surface layer) had less of an

  17. A new lunar high-Ti basalt type defined from clasts in Apollo 16 breccia 60639

    NASA Astrophysics Data System (ADS)

    Fagan, A. L.; Neal, C. R.

    2016-01-01

    This paper reports the detailed examination of three basalt clasts from Apollo 16 breccia 60639 that represent a new variant of high-Ti basalt returned from the Moon by the Apollo 16 mission. Mineral chemistry and whole-rock analyses were conducted on aliquots from three clasts (breccia matrix, basalt, and basalt + breccia matrix). The basalt clasts, which are not overtly porphyritic, contain compositionally zoned pyroxene, olivine, and plagioclase crystals that represent the evolution of the magma during crystallization; ilmenite does not exhibit major-element compositional zoning within individual crystals. Mineral compositions are distinct between the basalt and breccia matrix lithologies. In addition, whole-rock analyses identify clear compositional differences between the basalt and breccia matrix lithologies in both major and trace element concentrations. The composition of the mixed lithology aliquots (i.e., basalt + breccia matrix) do not indicate simple two component mixing (i.e., compositions are not intermediate to the basalt and breccia end-members); this apparent incongruity can be accounted for by adding ∼19-40% plagioclase to an amalgamation of the average basalt and individual breccia clast compositions via impact mixing. Whole-rock analyses are consistent with previous analyses of one 60639 basalt clast, which were interpreted to indicate chemical similarity with Apollo 11 and 17 basalts. However, both major and trace elements suggest that the 60639 basalt clasts examined here have compositions that are distinct from Apollo 11 and 17 high-Ti basalts. Although the 60639 basalt clasts have similar characteristics to a variety of previously identified basalt types, the more extensive whole-rock analyses reported here indicate that they represent a type of Apollo high-Ti basalt heretofore unrecognized in the Apollo and lunar meteorite collections. By placing these new analyses in the context of other mare basalt compositions, a petrogenetic model for

  18. Saturation diving; physiology and pathophysiology.

    PubMed

    Brubakk, Alf O; Ross, John A S; Thom, Stephen R

    2014-07-01

    In saturation diving, divers stay under pressure until most of their tissues are saturated with breathing gas. Divers spend a long time in isolation exposed to increased partial pressure of oxygen, potentially toxic gases, bacteria, and bubble formation during decompression combined with shift work and long periods of relative inactivity. Hyperoxia may lead to the production of reactive oxygen species (ROS) that interact with cell structures, causing damage to proteins, lipids, and nucleic acid. Vascular gas-bubble formation and hyperoxia may lead to dysfunction of the endothelium. The antioxidant status of the diver is an important mechanism in the protection against injury and is influenced both by diet and genetic factors. The factors mentioned above may lead to production of heat shock proteins (HSP) that also may have a negative effect on endothelial function. On the other hand, there is a great deal of evidence that HSPs may also have a "conditioning" effect, thus protecting against injury. As people age, their ability to produce antioxidants decreases. We do not currently know the capacity for antioxidant defense, but it is reasonable to assume that it has a limit. Many studies have linked ROS to disease states such as cancer, insulin resistance, diabetes mellitus, cardiovascular diseases, and atherosclerosis as well as to old age. However, ROS are also involved in a number of protective mechanisms, for instance immune defense, antibacterial action, vascular tone, and signal transduction. Low-grade oxidative stress can increase antioxidant production. While under pressure, divers change depth frequently. After such changes and at the end of the dive, divers must follow procedures to decompress safely. Decompression sickness (DCS) used to be one of the major causes of injury in saturation diving. Improved decompression procedures have significantly reduced the number of reported incidents; however, data indicate considerable underreporting of injuries

  19. Saturation diving; physiology and pathophysiology.

    PubMed

    Brubakk, Alf O; Ross, John A S; Thom, Stephen R

    2014-07-01

    In saturation diving, divers stay under pressure until most of their tissues are saturated with breathing gas. Divers spend a long time in isolation exposed to increased partial pressure of oxygen, potentially toxic gases, bacteria, and bubble formation during decompression combined with shift work and long periods of relative inactivity. Hyperoxia may lead to the production of reactive oxygen species (ROS) that interact with cell structures, causing damage to proteins, lipids, and nucleic acid. Vascular gas-bubble formation and hyperoxia may lead to dysfunction of the endothelium. The antioxidant status of the diver is an important mechanism in the protection against injury and is influenced both by diet and genetic factors. The factors mentioned above may lead to production of heat shock proteins (HSP) that also may have a negative effect on endothelial function. On the other hand, there is a great deal of evidence that HSPs may also have a "conditioning" effect, thus protecting against injury. As people age, their ability to produce antioxidants decreases. We do not currently know the capacity for antioxidant defense, but it is reasonable to assume that it has a limit. Many studies have linked ROS to disease states such as cancer, insulin resistance, diabetes mellitus, cardiovascular diseases, and atherosclerosis as well as to old age. However, ROS are also involved in a number of protective mechanisms, for instance immune defense, antibacterial action, vascular tone, and signal transduction. Low-grade oxidative stress can increase antioxidant production. While under pressure, divers change depth frequently. After such changes and at the end of the dive, divers must follow procedures to decompress safely. Decompression sickness (DCS) used to be one of the major causes of injury in saturation diving. Improved decompression procedures have significantly reduced the number of reported incidents; however, data indicate considerable underreporting of injuries

  20. Gold solubility and partitioning between sulfide liquid, monosulfide solid solution and hydrous mantle melts: Implications for the formation of Au-rich magmas and crust-mantle differentiation

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Audétat, Andreas

    2013-10-01

    The solubility of Au in sulfur-free vs. sulfide-saturated melts and its partitioning behavior between sulfide liquid (SL), monosulfide solid solution (MSS) and hydrous basanite melt at variable Au activities was investigated in a fO2 range of FMQ-2 to FMQ+1.6 at 1200 °C/1.5 GPa using piston cylinder apparatus. Gold solubility in sulfur-free (<100 μg/g S) melt is low (0.6-1.6 μg/g) and increases with fO2 in a manner consistent with Au dissolution as AuO1/2, whereas in sulfide-saturated melts it is high (13.6 ± 1.7 μg/g) and independent of fO2. Variations in the chlorine content of sulfide-saturated melts (0.2-1.2 wt% Cl) had no measurable effect on Au solubility. Gold partition coefficients between sulfide liquid and silicate melt (DAuSL/SM) are very high, ∼10,000 ± 3000, which is at the upper end of values reported in previous studies. Gold partition coefficients between MSS and silicate melt (DAuMSS/SM) are much lower, 60 ± 10, which is at the lower end of previous values. Both DAuSL/SM and DAuMSS/SM are independent of fO2. The new Au partition coefficients were used in conjunction with previously published Cu and Ag partition coefficients to investigate the role of MSS versus SL during partial melting in the source region of primitive potassic magmas and during crust-mantle differentiation. The high Au content of ore deposits associated with potassic magmas has commonly been explained by the dissolution of Au-rich sulfide liquid, either during partial melting in the mantle source or during partial re-melting of sulfide-bearing cumulates at the crust-mantle boundary. We argue that MSS is the dominant sulfide phase in the mantle source region of these magmas, and thus that their high Au content is a consequence of low MSS-silicate melt partition coefficients rather than of sulfide exhaustion or partial re-melting of sulfide-bearing cumulates. Continental crust is depleted in Au, Ag and Cu relative to mantle melts, which was thought to be due to removal of

  1. Continuous measurement of dissolved sulfide in sewer systems.

    PubMed

    Sutherland-Stacey, L; Corrie, S; Neethling, A; Johnson, I; Gutierrez, O; Dexter, R; Yuan, Z; Keller, J; Hamilton, G

    2008-01-01

    Sulfides are particularly problematic in the sewage industry. Hydrogen sulfide causes corrosion of concrete infrastructure, is dangerous at high concentrations and is foul smelling at low concentrations. Despite the importance of sulfide monitoring there is no commercially available system to quantify sulfide in waste water. In this article we report on our use of an in situ spectrometer to quantify bisulfide in waste water and additional analysis with a pH probe to calculate total dissolved sulfide. Our results show it is possible to use existing commercially available and field proven sensors to measure sulfide to mg/l levels continuously with little operator intervention and no sample preparation. PMID:18309215

  2. Process for producing cadmium sulfide on a cadmium telluride surface

    DOEpatents

    Levi, Dean H.; Nelson, Art J.; Ahrenkiel, Richard K.

    1996-01-01

    A process for producing a layer of cadmium sulfide on a cadmium telluride surface to be employed in a photovoltaic device. The process comprises providing a cadmium telluride surface which is exposed to a hydrogen sulfide plasma at an exposure flow rate, an exposure time and an exposure temperature sufficient to permit reaction between the hydrogen sulfide and cadmium telluride to thereby form a cadmium sulfide layer on the cadmium telluride surface and accomplish passivation. In addition to passivation, a heterojunction at the interface of the cadmium sulfide and the cadmium telluride can be formed when the layer of cadmium sulfide formed on the cadmium telluride is of sufficient thickness.

  3. Animal adaptations for tolerance and exploitation of poisonous sulfide.

    PubMed

    Grieshaber, M K; Völkel, S

    1998-01-01

    Many aquatic animal species can survive sulfide exposure to some extent through oxidation of the sulfide, which results mainly in thiosulfate. In several species, sulfide oxidation is localized in the mitochondria and is accompanied by ATP synthesis. In addition, blood-based and intracellular compounds can augment sulfide oxidation. The formation of thiosulfate requires oxygen, which results in an increase in oxygen consumption of some species. If not all sulfide is detoxified, cytochrome C oxidase is inhibited. Under these conditions, a sulfide-dependent anaerobic energy metabolism commences. PMID:9558453

  4. Paleosecular variation, geochemistry, correlation, and timing of Grande Ronde Basalt lava flows, Columbia River Basalt Group

    NASA Astrophysics Data System (ADS)

    Hagstrum, J. T.; Sawlan, M. G.

    2013-12-01

    Co-located paleomagnetic and geochemical sampling of lava flows at eight sections within the Grande Ronde Basalt (GRB) was undertaken across the Columbia Plateau in WA and OR. The GRB represents roughly 87% (151,000 km3) of the Miocene Columbia River flood basalt province (174,000 km3) by volume (exclusive of the Steens Mountain Basalt), and recently published 40Ar/39Ar age estimates indicate that it was most likely emplaced within a time interval of less than 400 ka [Barry et al., Lithos 118(3), 213-222, 2010]. GRB flows include four stratigraphic magnetozones within the formation (R1, N1, R2, N2), and the sections currently sampled are mostly within the upper two magnetozones. Because Plateau GRB flows have undergone pervasive low-temperature alteration to varying degrees [see M. Sawlan's abstract, this meeting], particular care has been taken to collect the freshest available rock. Several new flow units have been identified, and similar, but unusual, paleomagnetic directions in stratigraphically adjacent flows of different chemical composition indicate, with high probability, that these flows were emplaced contemporaneously relative to the rate of geomagnetic paleosecular variation (PSV). Thus, several magma sources and their vent systems apparently operated nearly simultaneously and produced a stratigraphic framework in which compositionally distinct flows are intercalated. In addition, transitional directions have been found in flows near the N1/R2 and R2/N2 geomagnetic reversal boundaries, and an excursion to low inclinations occurred during emplacement of the Winter Water member (N2) flows. The detail and sequential nature of the PSV curve recovered from the upper GRB lava flows (R2 & N2) so far indicate extraordinarily rapid eruption of these flows. Comparison of the rate of change shown by our nascent PSV curve for the upper GRB with a recently published one for the Holocene of western North America [Hagstrum and Blinman, G3 11(6), 2010], which covers in

  5. Basalt here, basalt there: Constraining the basaltic nature of eight Vp-type asteroids in the inner and outer main asteroid belt

    NASA Astrophysics Data System (ADS)

    Hardersen, Paul Scott; Reddy, Vishnu

    2016-10-01

    The distribution and abundance of basaltic material in the main asteroid belt has multiple implications that impact our understanding of the physical and thermal conditions that existed in the inner solar system during the formation epoch about 4.6 Gyr ago. Subjects impacted by a more accurate basaltic asteroid inventory include the efficacy of current inner solar system heating model predictions (Al-26 and T Tauri induction heating), the existence of differentiated parent bodies other than (4) Vesta, the dispersion efficiency of Vestoids by YORP forces, and the predictive ability of the V-taxonomy in predicting a basaltic surface composition. This work reports on a continuation of an effort to better constrain the basaltic asteroid population in the main asteroid belt with the goal of observing about 650 Vp-type asteroids. This work focuses on two populations: a) those Vp-classified asteroids (Carvano et al., 2010) in the spatial vicinity of (4) Vesta (candidate Vestoids) in the inner main belt, and b) Vp-classified asteroids in the outer main belt beyond 2.5 AU. Thus far, 23 Vp-type asteroids and candidate Vestoids have been observed and analyzed, which are all strongly suggestive of a basaltic surface composition (Hardersen et al., 2014, 2015, 2016 (in preparation)). However, unpublished work is beginning to show that the Vp taxonomic class is less accurate in its ability to identify basaltic surface compositions in outer-belt Vp-type asteroids. We report here on an additional set of Vp-type asteroids that were observed at the NASA Infrared Telescope Facility (IRTF) in December 2015 and January 2016. All observations were obtained with the SpeX spectrograph in prism mode with spectral range from 0.7 to 2.5 microns. They include (4900) Maymelou, (7302) 1993 CQ, (9064) Johndavies, (9531) Jean-Luc, (11341) Babbage, (17480) 1991 PE10, (20171) 1996 WC2, and (25849) 2000 ET107. We present average near-infrared (NIR) reflectance spectra of each asteroid, determine the

  6. Hydrogen Sulfide Inhibits Amyloid Formation

    PubMed Central

    2015-01-01

    Amyloid fibrils are large aggregates of misfolded proteins, which are often associated with various neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s, and vascular dementia. The amount of hydrogen sulfide (H2S) is known to be significantly reduced in the brain tissue of people diagnosed with Alzheimer’s disease relative to that of healthy individuals. These findings prompted us to investigate the effects of H2S on the formation of amyloids in vitro using a model fibrillogenic protein hen egg white lysozyme (HEWL). HEWL forms typical β-sheet rich fibrils during the course of 70 min at low pH and high temperatures. The addition of H2S completely inhibits the formation of β-sheet and amyloid fibrils, as revealed by deep UV resonance Raman (DUVRR) spectroscopy and ThT fluorescence. Nonresonance Raman spectroscopy shows that disulfide bonds undergo significant rearrangements in the presence of H2S. Raman bands corresponding to disulfide (RSSR) vibrational modes in the 550–500 cm–1 spectral range decrease in intensity and are accompanied by the appearance of a new 490 cm–1 band assigned to the trisulfide group (RSSSR) based on the comparison with model compounds. The formation of RSSSR was proven further using a reaction with TCEP reduction agent and LC-MS analysis of the products. Intrinsic tryptophan fluorescence study shows a strong denaturation of HEWL containing trisulfide bonds. The presented evidence indicates that H2S causes the formation of trisulfide bridges, which destabilizes HEWL structure, preventing protein fibrillation. As a result, small spherical aggregates of unordered protein form, which exhibit no cytotoxicity by contrast with HEWL fibrils. PMID:25545790

  7. Hydrogen Sulfide and Urogenital Tract.

    PubMed

    di Villa Bianca, Roberta d'Emmanuele; Cirino, Giuseppe; Sorrentino, Raffaella

    2015-01-01

    In this chapter the role played by H2S in the physiopathology of urogenital tract revising animal and human data available in the current relevant literature is discussed. H2S pathway has been demonstrated to be involved in the mechanism underlying penile erection in human and experimental animal. Both cystathionine-β synthase (CBS) and cystathionine-γ lyase (CSE) are expressed in the human corpus cavernosum and exogenous H2S relaxes isolated human corpus cavernosum strips in an endothelium-independent manner. Hydrogen sulfide pathway also accounts for the direct vasodilatory effect operated by testosterone on isolated vessels. Convincing evidence suggests that H2S can influence the cGMP pathway by inhibiting the phosphodiesterase 5 (PDE-5) activity. All these findings taken together suggest an important role for the H2S pathway in human corpus cavernosum homeostasis. However, H2S effect is not confined to human corpus cavernosum but also plays an important role in human bladder. Human bladder expresses mainly CBS and generates in vitro detectable amount of H2S. In addition the bladder relaxant effect of the PDE-5 inhibitor sildenafil involves H2S as mediator. In conclusion the H2S pathway is not only involved in penile erection but also plays a role in bladder homeostasis. In addition the finding that it involved in the mechanism of action of PDE-5 inhibitors strongly suggests that modulation of this pathway can represent a therapeutic target for the treatment of erectile dysfunction and bladder diseases. PMID:26162831

  8. Breakthroughs in Seismic and Borehole Characterization of Basalt Sequestration Targets

    SciTech Connect

    Sullivan, E. C.; Hardage, Bob A.; McGrail, B. Peter; Davis, Klarissa N.

    2011-04-01

    Mafic continental flood basalts form a globally important, but under-characterized CO2 sequestration target. The Columbia River Basalt Group (CRBG) in the northwestern U.S. is up to 5 km thick and covers over 168,000 km2. In India, flood basalts are 3 km thick and cover greater than 500,000 km2. Laboratory experiments demonstrate that the CRBG and other basalts react with formation water and super critical (sc) CO2 to precipitate carbonates, thus adding a potential mineral trapping mechanism to the standard trapping mechanisms of most other types of CO2 sequestration reservoirs. Brecciated tops of individual basalt flows in the CRBG form regional aquifers that locally have greater than 30% porosity and three Darcies of permeability. Porous flow tops are potential sites for sequestration of gigatons of scCO2 in areas where the basalts contain unpotable water and are at depths greater than 800 m. In this paper we report on the U.S. DOE Big Sky Regional Carbon Sequestration Partnership surface seismic and borehole geophysical characterization that supports a field test of capacity, integrity, and geochemical reactivity of CRBG reservoirs in eastern Washington, U.S.A. Traditional surface seismic methods have had little success in imaging basalt features in on-shore areas where the basalt is thinly covered by sediment. Processing of the experimental 6.5 km, 5 line 3C seismic swath included constructing an elastic wavefield model, identifying and separating seismic wave modes, and processing the swath as a single 2D line. Important findings include: (1) a wide variety of shear wave energy modes swamp the P-wave seismic records; (2) except at very short geophone offsets, ground roll overprints P-wave signal; and (3) because of extreme velocity contrasts, P-wave events are refracted at incidence angles greater than 7-15 degrees. Subsequent removal of S-wave and other noise during processing resulted in tremendous improvement in image quality. The application of wireline

  9. Petrogenesis of pillow basalts from Baolai in southwestern Taiwan

    NASA Astrophysics Data System (ADS)

    Liu, Chih-Chun; Yang, Huai-Jen

    2016-04-01

    The pillow basalts from Baolai in southwestern Taiwan have been inferred to bear Dupal signautres based on their Th/Ce ratio, linking the Baolai basalts to the South China Sea (SCS) seamounts that are characterized by Dupal Pb isotope signatures (Smith and Lewis, 2007). In this study, thirty-two Baolai basalt samples were analyzed for abundances of major and trace elements as well as Pb and Nd isotope ratios to verify their Dupal characters and to constrain their petrogenesis significance. The Baolai basalts contain 4-10 % L.O.I.. Three stages of alteration are inferred from plots of L.O.I. abundance versus concentrations major oxides as well as mineral textures and compositions. The first alteration stage was characterized by albitization that converted Ca-rich plagioclase to albite. The second alteration stage was dominated by chloritization of olivine and augite, resulting in increases in L.O.I. abundance. The last alteration stage is represented by formation of secondary calcite in vesicles and cracks. These alteration processes reflect interaction with seawater and apparently did not affect the magmatic Pb isotope composition for the low Pb concentration in seawater. Relative to the North Hemisphere Reference Line (NHRL), the Baolai pillow basalts have higher 208Pb/204Pb ratios at a given 206Pb/204Pb value, showing Dupal anomaly. For their relatively higher 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios, the Baolai basalts are distinct from majority of the Cenozoic basalts in the Hainan-Leizhou peninsula, the Indochina peninsula, and the SCS seamounts, for which derivation from the Hainan mantle plume has been recently proposed (Wang et al., 2013). In contrast, the Baolai basalts and the Cenozoic basalts from eastern Guangdong at southeastern China have similar Pb and Nd isotope compositions, indicating derivation from similar mantle sources. However, the Baolai basalts have lower abundance ratios of Zr/Hf (40.3-45.6 versus 46.5-50.5), La/Yb (12

  10. Effect of carbon nanotube addition on the wear behavior of basalt/epoxy woven composites.

    PubMed

    Kim, M T; Rhee, K Y; Lee, B H; Kim, C J

    2013-08-01

    The effect of acid-treated carbon nanotube (CNT) addition on the wear and dynamic mechanical thermal properties of basalt/epoxy woven composites was investigated in this study. Basalt/CNT/epoxy composites were fabricated by impregnating woven basalt fibers into epoxy resin mixed with 1 wt% CNTs which were acid-treated. Wear and DMA (dynamic mechanical analyzer) tests were performed on basalt/epoxy composites and basalt/CNT/epoxy composites. The results showed that the addition of the acid-treated CNTs improved the wear properties of basalt/epoxy woven composites. Specifically, the friction coefficient of the basalt/epoxy composite was stabilized in the range of 0.5-0.6 while it fell in the range of 0.3-0.4 for basalt/CNT/epoxy composites. The wear volume loss of the basalt/CNT/epoxy composites was approximately 68% lower than that of the basalt/epoxy composites. The results also showed that the glass transition temperature of basalt/CNT/epoxy composites was higher than that of basalt/epoxy composites. The improvement of wear properties of basalt/epoxy composites by the addition of acid-treated CNTs was caused by the homogeneous load transfer between basalt fibers and epoxy matrix due to the reinforcement of CNTs.

  11. Basalt-radionuclide distribution coefficient determinations. FY-1979 annual report

    SciTech Connect

    Ames, L.L.; McGarrah, J.E.

    1980-09-01

    Experimental radionuclide distribution coefficients (Kd') were determined for Pomona, Flow E, Umtanum basalts, and secondary mineralization associated with Pomona basalt at 23/sup 0/, 60/sup 0/ and 150/sup 0/C. Radionuclides used were /sup 75/Se, /sup 85/Sr, /sup 99/Tc, /sup 125/I, /sup 135/Cs, /sup 226/Ra, /sup 237/Np, /sup 238/U, /sup 241/Am, and /sup 241/Pu. Solution oxygen contents were controlled by the basalt/groundwater system (Eh = 600 to 700 mV), and were high (8.2 to 8.4 mg/l) at 23/sup 0/C. Oxygen contents and pH changed little in contact with basalt. The effects of temperature changes on radionuclide Kd' results varied depending upon the radionuclide involved, solution-solid reactions, and the relationship of the radionuclide to these reactions. For example, cesium Kd' values decreased from 3100 ml/g for Umtanum basalt at 23/sup 0/C to 120 ml/g at 150/sup 0/C. At the same time, strontium Kd' values increased for Umtanum basalt from 105 ml/g at 23/sup 0/C to complete removal at 150/sup 0/C and 40 days. Radionuclide adsorption coefficient measurements at higher temperatures and pressures were made in addition to the 23/sup 0/C, solution-solid contact time-conditional Kd (Kd') measurements. These include Kd' measurements with Umtanum basalt, Pomona basalt, Flow E basalt and secondary mineralization and radioisotopes of americium, cesium, iodine, neptunium, plutonium, radium, selenium, strontium, technetium and uranium. The additional temperatures involved were 60/sup 0/C, 150/sup 0/C, and 300/sup 0/C. At 150/sup 0/C, argon pressures of 6.9, 13.8, 20.7, and 27.6 MPa will be used to ascertain the effects of pressure changes on Kd' values. So far only the 6.9 MPa argon pressure has been investigated. The upper temperature of 250/sup 0/C is where thermal breakdown of dioctahedral smectites (secondary mineralization) begins.

  12. Preliminary Hydrogeologic Characterization Results from the Wallula Basalt Pilot Study

    SciTech Connect

    B.P. McGrail; E. C. Sullivan; F. A. Spane; D. H. Bacon; G. Hund; P. D. Thorne; C. J. Thompson; S. P. Reidel; F. S. Colwell

    2009-12-01

    The DOE's Big Sky Regional Carbon Sequestration Partnership has completed drilling the first continental flood basalt sequestration pilot borehole to a total depth (TD) of 4,110 feet on the Boise White Paper Mill property at Wallula, Washington. Site suitability was assessed prior to drilling by the 2007-2008 acquisition, processing and analysis of a four-mile, five-line three component seismic swath, which was processed as a single data-dense line. Analysis of the seismic survey data indicated a composite basalt formation thickness of {approx}8,000 feet and absence of major geologic structures (i.e., faults) along the line imaged by the seismic swath. Drilling of Wallula pilot borehole was initiated on January 13, 2009 and reached TD on April 6, 2009. Based on characterization results obtained during drilling, three basalt breccia zones were identified between the depth interval of 2,716 and 2,910 feet, as being suitable injection reservoir for a subsequent CO2 injection pilot study. The targeted injection reservoir lies stratigraphically below the massive Umtanum Member of the Grande Ronde Basalt, whose flow-interior section possesses regionally recognized low-permeability characteristics. The identified composite injection zone reservoir provides a unique and attractive opportunity to scientifically study the reservoir behavior of three inter-connected reservoir intervals below primary and secondary caprock confining zones. Drill cuttings, wireline geophysical logs, and 31one-inch diameter rotary sidewall cores provided geologic data for characterization of rock properties. XRF analyses of selected rock samples provided geochemical characterizations of the rocks and stratigraphic control for the basalt flows encountered by the Wallula pilot borehole. Based on the geochemical results, the pilot borehole was terminated in the Wapshilla Ridge 1 flow of the Grande Ronde Basalt Formation. Detailed hydrologic test characterizations of 12 basalt interflow reservoir

  13. Phase Engineering of 2D Tin Sulfides.

    PubMed

    Mutlu, Zafer; Wu, Ryan J; Wickramaratne, Darshana; Shahrezaei, Sina; Liu, Chueh; Temiz, Selcuk; Patalano, Andrew; Ozkan, Mihrimah; Lake, Roger K; Mkhoyan, K A; Ozkan, Cengiz S

    2016-06-01

    Tin sulfides can exist in a variety of phases and polytypes due to the different oxidation states of Sn. A subset of these phases and polytypes take the form of layered 2D structures that give rise to a wide host of electronic and optical properties. Hence, achieving control over the phase, polytype, and thickness of tin sulfides is necessary to utilize this wide range of properties exhibited by the compound. This study reports on phase-selective growth of both hexagonal tin (IV) sulfide SnS2 and orthorhombic tin (II) sulfide SnS crystals with diameters of over tens of microns on SiO2 substrates through atmospheric pressure vapor-phase method in a conventional horizontal quartz tube furnace with SnO2 and S powders as the source materials. Detailed characterization of each phase of tin sulfide crystals is performed using various microscopy and spectroscopy methods, and the results are corroborated by ab initio density functional theory calculations. PMID:27099950

  14. Phase Engineering of 2D Tin Sulfides.

    PubMed

    Mutlu, Zafer; Wu, Ryan J; Wickramaratne, Darshana; Shahrezaei, Sina; Liu, Chueh; Temiz, Selcuk; Patalano, Andrew; Ozkan, Mihrimah; Lake, Roger K; Mkhoyan, K A; Ozkan, Cengiz S

    2016-06-01

    Tin sulfides can exist in a variety of phases and polytypes due to the different oxidation states of Sn. A subset of these phases and polytypes take the form of layered 2D structures that give rise to a wide host of electronic and optical properties. Hence, achieving control over the phase, polytype, and thickness of tin sulfides is necessary to utilize this wide range of properties exhibited by the compound. This study reports on phase-selective growth of both hexagonal tin (IV) sulfide SnS2 and orthorhombic tin (II) sulfide SnS crystals with diameters of over tens of microns on SiO2 substrates through atmospheric pressure vapor-phase method in a conventional horizontal quartz tube furnace with SnO2 and S powders as the source materials. Detailed characterization of each phase of tin sulfide crystals is performed using various microscopy and spectroscopy methods, and the results are corroborated by ab initio density functional theory calculations.

  15. Convective Regimes in Crystallizing Basaltic Magma Chambers

    NASA Astrophysics Data System (ADS)

    Gilbert, A. J.; Neufeld, J. A.; Holness, M. B.

    2015-12-01

    Cooling through the chamber walls drives crystallisation in crustal magma chambers, resulting in a cumulate pile on the floor and mushy regions at the walls and roof. The liquid in many magma chambers, either the bulk magma or the interstitial liquid in the mushy regions, may convect, driven either thermally, due to cooling, or compositionally, due to fractional crystallization. We have constructed a regime diagram of the possible convective modes in a system containing a basal mushy layer. These modes depend on the large-scale buoyancy forcing characterised by a global Rayleigh number and the proportion of the chamber height constituting the basal mushy region. We have tested this regime diagram using an analogue experimental system composed of a fluid layer overlying a pile of almost neutrally buoyant inert particles. Convection in this system is driven thermally, simulating magma convection above and within a porous cumulate pile. We observe a range of possible convective regimes, enabling us to produce a regime diagram. In addition to modes characterised by convection of the bulk and interstitial fluid, we also observe a series of regimes where the crystal pile is mobilised by fluid motions. These regimes feature saltation and scouring of the crystal pile by convection in the bulk fluid at moderate Rayleigh numbers, and large crystal-rich fountains at high Rayleigh numbers. For even larger Rayleigh numbers the entire crystal pile is mobilised in what we call the snowglobe regime. The observed mobilisation regimes may be applicable to basaltic magma chambers. Plagioclase in basal cumulates crystallised from a dense magma may be a result of crystal mobilisation from a plagioclase-rich roof mush. Compositional convection within such a mush could result in disaggregation, enabling the buoyant plagioclase to be entrained in relatively dense descending liquid plumes and brought to the floor. The phenocryst load in porphyritic lavas is often interpreted as a

  16. Geochronology, petrology and Hf-S isotope geochemistry of the newly-discovered Xiarihamu magmatic Ni-Cu sulfide deposit in the Qinghai-Tibet plateau, western China

    NASA Astrophysics Data System (ADS)

    Li, Chusi; Zhang, Zhaowei; Li, Wenyuan; Wang, Yalei; Sun, Tao; Ripley, Edward M.

    2015-02-01

    This paper reports the first set of data for the newly-discovered Xiarihamu magmatic Ni-Cu sulfide deposit in the Eastern Kunlun Paleozoic arc terrane which is located in the northern part of the Qinghai-Tibet plateau. An on-going drilling campaign reveals ~ 100 million tons of sulfide mineralization with the average grade of 0.8 wt.% Ni and 0.1 wt.% Cu for the deposit. This makes the Xiarihamu deposit one of the 20 largest magmatic Ni-Cu sulfide deposits in the world and the largest ever found in arc settings. The deposit is hosted in a small ultramafic body intruding older gabbroic and metamorphic rocks. New zircon U-Pb isotope age data reveal that the ultramafic body (411.6 ± 2.4 Ma) is ~ 20 Ma younger than the host gabbroic intrusion (431.3 ± 2.1 Ma). The ultramafic body is composed predominantly of lherzolite and olivine websterite, with minor dunite, websterite and orthopyroxenite. Mineralization mainly occurs as sub-horizontal to gently dipping (< 30°) disseminated sulfide zones that are generally concordant with the lithological structure of the ultramafic intrusion. The lateral extension and thickness of individual mineralized zones are up to ~ 200 m and ~ 100 m, respectively. Sulfide mineral assemblages are composed of pyrrhotite, pentlandite and chalcopyrite. The Xiarihamu ultramafic rocks show light REE enrichments and pronounced negative Nb anomalies, plus significant Ca-depletion in olivine (< 700 ppm Ca), which are characteristic of many arc basalts in the world. Olivine crystals in the Xiarihamu ultramafic rocks have relatively primitive compositions, with Fo contents up to 90 mol%, close to the mantle value. The contrasting Ni contents of olivine crystals with similar Fo contents from different sulfide-mineralized zones in a single drill core indicate that at least two pulses of sulfide-laden magma with different Ni compositions were involved in the development of the deposit. Estimated parental magma for the Xiarihamu lherzolites contains 52

  17. Similar Microbial Communities Found on Two Distant Seafloor Basalts.

    PubMed

    Singer, Esther; Chong, Lauren S; Heidelberg, John F; Edwards, Katrina J

    2015-01-01

    The oceanic crust forms two thirds of the Earth's surface and hosts a large phylogenetic and functional diversity of microorganisms. While advances have been made in the sedimentary realm, our understanding of the igneous rock portion as a microbial habitat has remained limited. We present the first comparative metagenomic microbial community analysis from ocean floor basalt environments at the Lō'ihi Seamount, Hawai'i, and the East Pacific Rise (EPR; 9°N). Phylogenetic analysis indicates the presence of a total of 43 bacterial and archaeal mono-phyletic groups, dominated by Alpha- and Gammaproteobacteria, as well as Thaumarchaeota. Functional gene analysis suggests that these Thaumarchaeota play an important role in ammonium oxidation on seafloor basalts. In addition to ammonium oxidation, the seafloor basalt habitat reveals a wide spectrum of other metabolic potentials, including CO2 fixation, denitrification, dissimilatory sulfate reduction, and sulfur oxidation. Basalt communities from Lō'ihi and the EPR show considerable metabolic and phylogenetic overlap down to the genus level despite geographic distance and slightly different seafloor basalt mineralogy. PMID:26733957

  18. An ancient recipe for flood-basalt genesis.

    PubMed

    Jackson, Matthew G; Carlson, Richard W

    2011-07-27

    Large outpourings of basaltic lava have punctuated geological time, but the mechanisms responsible for the generation of such extraordinary volumes of melt are not well known. Recent geochemical evidence suggests that an early-formed reservoir may have survived in the Earth's mantle for about 4.5 billion years (ref. 2), and melts of this reservoir contributed to the flood basalt emplaced on Baffin Island about 60 million years ago. However, the volume of this ancient mantle domain and whether it has contributed to other flood basalts is not known. Here we show that basalts from the largest volcanic event in geologic history--the Ontong Java plateau--also exhibit the isotopic and trace element signatures proposed for the early-Earth reservoir. Together with the Ontong Java plateau, we suggest that six of the largest volcanic events that erupted in the past 250 million years derive from the oldest terrestrial mantle reservoir. The association of these large volcanic events with an ancient primitive mantle source suggests that its unique geochemical characteristics--it is both hotter (it has greater abundances of the radioactive heat-producing elements) and more fertile than depleted mantle reservoirs-may strongly affect the generation of flood basalts.

  19. Similar Microbial Communities Found on Two Distant Seafloor Basalts.

    PubMed

    Singer, Esther; Chong, Lauren S; Heidelberg, John F; Edwards, Katrina J

    2015-01-01

    The oceanic crust forms two thirds of the Earth's surface and hosts a large phylogenetic and functional diversity of microorganisms. While advances have been made in the sedimentary realm, our understanding of the igneous rock portion as a microbial habitat has remained limited. We present the first comparative metagenomic microbial community analysis from ocean floor basalt environments at the Lō'ihi Seamount, Hawai'i, and the East Pacific Rise (EPR; 9°N). Phylogenetic analysis indicates the presence of a total of 43 bacterial and archaeal mono-phyletic groups, dominated by Alpha- and Gammaproteobacteria, as well as Thaumarchaeota. Functional gene analysis suggests that these Thaumarchaeota play an important role in ammonium oxidation on seafloor basalts. In addition to ammonium oxidation, the seafloor basalt habitat reveals a wide spe