Search

The Xiarihamu Cu--Ni sulfide deposit is the second-largest Cu--Ni deposit in China, located in the Eastern Kunlun orogenic belt. However, despite previous study, the formation and evolution of this deposit remains a key unknown in the tectonic evolution of the Eastern Kunlun Orogenic Belt. Moreover, the petrogenesis of the ore-bearing rocks and the nature of ore genesis are the subjects of ongoing debate. Here, we present detailed field observations, petrology, zircon U--Pb geochronology, and Re--Os isotopic analyses to constrain the timing and genesis of the Xiarihamu Cu--Ni sulfide deposit. Sulfides from the massive ores yielded a Re--Os isotopic isochron age of 408 [+ or -] 11 Ma. Four samples from the ore-bearing Xiarihamu mafic-ultramafic intrusions yielded zircon U--Pb ages of 423.1 [+ or -] 2 Ma, 422.9 [+ or -] 3.1 Ma, 422.7 [+ or -] 2.3 Ma, and 422.6 [+ or -] 2.7 Ma, respectively, indicating that the ore formed during the Silurian. The calculated initial [.sup.187]Os/[.sup.188]Os ratio and [gamma]Os values ranged from 0.5109 to 0.8499 and from 311 to 584, respectively, indicating that crustal contamination played an extremely important role in triggering sulfide saturation. In combination with previous research, drill core observations and Re--Os data provide robust evidence for multiple pulses of magma replenishment throughout the process of ore genesis. Based on this evidence, the large-scale magmatic Cu--Ni mineralization in Xiarihamu likely occurred in a post-collisional setting related to tectonic slab breakoff. Key words: Xiarihamu Cu--Ni deposit, geochronology, Re--Os isotope, crustal contamination, Eastern Kunlun Orogenic belt. Le gisement sulfure de Cu--Ni de Xiarihamu, dans la ceinture orogenique du Kunlun oriental, est le deuxieme gisement de Cu--Ni en importance en Chine. Malgre certaines etudes anterieures, la formation et l'evolution de ce gisement dans le contexte de l'evolution tectonique de cette ceinture orogenique demeurent d'importantes inconnues. La petrogenese des roches mineralisees et la nature de la genese du minerai font en outre toujours l'objet de debats. Nous presentons des observations de terrain detaillees, ainsi que des donnees d'analyses petrologiques, de geochronologie U--Pb sur zircons et d'isotopes de Re--Os pour mieux definir l'age et la genese du gisement sulfure de Cu--Ni de Xiarihamu. Des sulfures provenant de minerais massifs ont donne un age d'isochrone pour les isotopes de Re--Os de 408 [+ or -] 11 Ma. Quatre echantillons d'intrusions mafiques--ultramafiques mineralisees de Xiarihamu ont donne des ages U--Pb sur zircons de 423,1 [+ or -] 2 Ma, 422,9 [+ or -] 3,1 Ma, 422,7 [+ or -] 2,3 Ma et 422,6 [+ or -] 2,7 Ma, respectivement, indiquant que le minerai s'est forme au Silurien. Les valeurs calculees du rapport [.sup.187]Os/[.sup.188]Os initial et de [gamma]Os vont de 0,5109 a 0,8499 et de 311 a 584, respectivement, indiquant que la contamination crustale a joue un role extremement important dans le declenchement de la saturation en sulfure. Combinees aux resultats de travaux anterieurs, des observations de carottes et des donnees de Re--Os fournissent des preuves robustes de plusieurs episodes d'apport de magma tout au long du processus de genese du minerai. A la lumiere de ces preuves, la mineralisation magmatique en Cu--Ni a grande echelle a Xiarihamu s'est vraisemblablement produite dans un milieu post-collision associe a la rupture d'une plaque tectonique subductee. [Traduit par la Redaction] Mots-cles : gisement de Cu--Ni de Xiarihamu, geochronologie, isotopes de Re--Os, contamination crustale, ceinture orogenique du Kunlun oriental., Introduction The Eastern Kunlun Orogenic Belt (EKOB) is an important metallogenic belt located in the western portion of the Central China Orogenic Belt. Large numbers of skarn, porphyry, and orogenic [...]

We propose a procedure for the simultaneous determination of biomarkers of the action of sulfur mustard (SM, 2,2'-dichlorodiethyl sulfide), namely, a depurinized adduct with DNA (N7-hydroxyethylthioethyl guanine) and an adduct with acetylcysteine (ACC) (1,1'-sulfonylbis[2-S-(N-acetylcysteinyl)ethane]), in urine by high-resolution HPLC-tandem mass spectrometry with electrospray ionization. The limit of quantification reached for both analytes is 10 ng/mL. The calibration plots are linear in the range 10-200 ng/mL. The procedure was tested in the analysis of urine samples obtained after the subcutaneous administration of sulfur mustard to rats in nonlethal dose (2 mg/kg) both in the absence of therapy and in using ACC as a scavenger (antidote). The positive effect of ACC therapy on the kinetics of sulfur mustard excretion from a body in the first hours after poisoning was found at the molecular level for the first time, and the protective effect of ACC on DNA in case of damage with sulfur mustard was substantiated., Author(s): O. I. Orlova [sup.1], G. V. Karakashev [sup.1], E. I. Savel'eva [sup.1] Author Affiliations: (1) Research Institute of Hygiene, Occupational Pathology, and Human Ecology, Federal Medical and Biological Agency [...]

We propose a new numerical workflow based on stochastic data integration where we merge a conceptual geological model, drillhole geophysical and geological logs, and surface geophysical data to compute a unified numerical model of a volcanogenic massive sulphide (VMS) deposit. The first step of the workflow consists in building a three-dimensional (3D) numerical conceptual model of the geology. This conceptual model, as well as geological logs, is then used to generate multiple equiprobable scenarios of the geology by means of multiple-point simulation (MPS). The MPS method studies high-order statistics in the space of a numerical conceptual model, making it possible to reproduce complex geological structures. We then use conventional conditional sequential Gaussian simulation, which is a method based on a node-by-node sequential process, to stochastically populate the geological grid with densities. For this purpose we use available density logs to simulate multiple equiprobable spatial distributions of the density at high spatial resolution within each geological unit separately. The stochastic high-resolution density models are iteratively combined by the gradual deformation method to minimize the difference between measured Bouguer anomaly data and the data computed on the combined realizations of density. Application of the proposed method to the Lalor deposit, a VMS deposit in Manitoba, Canada, produces a density model that honours the geology of the deposit and the Bouguer anomaly data. This unified model has the advantage to include all the available information (geological and density logs and surface geophysics) at scales appropriate for mining applications. Nous proposons un nouveau flux de travail numerique reposant sur l'integration stochastique de donnees dans lequel nous combinons un modele geologique conceptuel, les diagraphies geophysiques et geologiques, ainsi que les donnees geophysiques de surface pour obtenir un modele numerique unifie d'un gisement SMV. La premiere etape du flux de travail consiste en l'elaboration d'un modele conceptuel numerique 3D de la geologie. Ce modele conceptuel ainsi que les diagraphies geologiques sont utilises pour produire differents scenarios equiprobables de la geologie au moyen de la simulation multipoints (SMP). La methode SMP est utilisee pour examiner les statistiques d'ordre superieur dans l'espace d'un modele conceptuel numerique, rendant ainsi possible la reconstitution de structures geologiques complexes. Nous utilisons ensuite la simulation sequentielle gaussienne conditionnelle classique, une methode basee sur un processus sequentiel nceud-par-noeud pour remplir de maniere stochastique la grille geologique de valeurs de densite. A cette fin, nous utilisons des diagraphies de densite disponibles pour simuler differentes distributions spatiales equiprobables de la densite a haute resolution spatiale dans chaque unite geologique. Les modeles de densite stochastiques de haute resolution sont iterativement combines par la methode de deformation progressive afin de minimiser la difference entre les donnees d'anomalie de Bouguer mesurees et les donnees obtenues des realisations combinees de la densite. L'application de la methode proposee au gisement de Lalor, un gisement de sulfures massifs volcanogenes au Manitoba (Canada), produit un modele de densite qui reflete bien la geologie du gisement et les donnees d'anomalie de Bouguer. Ce modele unifie a l'avantage d'inclure toute l'information disponible (diagraphies geologiques et de densite et geophysique de surface) a des echelles convenant a des applications minieres. [Traduit par la Redaction], Introduction To understand the geometry and the spatial distribution of the physical properties of a deposit, many types of data must be collected, processed, and interpreted. This amount of diverse [...]

Magmatic-hydrothermal gold-copper deposits in post-subduction settings represent essential targets for mineral exploration, but controls on their formation remain controversial. The early Cretaceous lode Au districts that formed during lithosphere destruction of the North China Craton provide an ideal opportunity to better understand the key tectono-magmatic factors responsible for the genesis of Au-rich deposits in post-subduction settings. Here, we present a LA-ICP-MS study of silicate melt inclusions and sulfide inclusions from ore-related mafic to intermediate rocks in the central Taihangshan Au district in the interior of the North China Craton to constrain the content and evolution of magmatic ore metals ± volatiles. The results, combined with numerical modeling, suggest that the ore-related magmas contained only a few ng/g Au, which is similar to the Au content of non-mineralization-related mafic to intermediate magmas worldwide. The low Au content of the lode Au-related magmas suggest that large volumes of magmas had to accumulate in the middle to lower crust through trans-lithospheric fault systems to produce the lode Au deposits. It is further suggested that the lode Au-related magmas were alkali-rich, hydrous, oxidized and relatively rich in sulfur and chlorine (mafic melt inclusions contain 0.14â0.24 wt% S and 0.1â0.2 wt% Cl). These properties are considered critical for the generation of auriferous ore fluids. By comparing the tectono-magmatic setting of the giant Jiaodong Au province (~ 4000 t Au) with the central Taihangshan district (~ 150 t Au), we propose that the much larger total Au tonnage of the Jiaodong district results from the accumulation of a much larger volume of ore-forming magmas at deep crustal levels, induced by a stronger degree of lithosphere modification. In addition, given that the composition of lode Au-related magmas is similar to that of porphyry Cu-Au-related magmas, the lack of giant, early Cretaceous porphyry Cu-Au deposits in the North China Craton suggests that strong extensional settings favor the formation of lode Au deposits instead of porphyry Cu-Au deposits. The present study, therefore, has general implications for the genesis of Au-rich deposits in strongly extensional settings., Author(s): Jia Chang [sup.1] [sup.2], Andreas Audétat [sup.2], Jian-Wei Li [sup.1] Author Affiliations: (1) grid.503241.1, 0000 0004 1760 9015, School of Earth Resources and State Key Laboratory of Geological Processes [...]

The results of model experiments on the effect of transition elements (iron, manganese) and sulfide ions on the values of chemical (COD) and biochemical oxygen demand (BOD) are presented. It is shown that, in the presence of transition elements in water, BOD is overestimated. In the presence of 100 mg/L of iron(II) and >0.05 mg/L of sulfides in water, the BOD values exceed those of COD., Author(s): A. M. Safarov [sup.1], R. M. Khatmullina [sup.2], V. I. Safarova [sup.2], A. R. Mukhamatdinova [sup.2], V. Z. Latypova [sup.3], G. F. Shaidulina [sup.2], A. A. Kovbota [sup.1] Author [...]

The 3.1 Ga Nuggihalli greenstone belt in the Western Dharwar craton is comprised of chromitite-bearing sill-like ultramafic-mafic rocks that are surrounded by metavolcanic schists (compositionally komatiitic to komatiitic basalts) and a suite of tonalite-trondhjemite-granodiorite gneissic rocks. The sill-like plutonic unit consists of a succession of serpentinite (after dunite)-peridotite-pyroxenite and gabbro with bands of titaniferous magnetite ore. The chromitite ore-bodies (length [almost equal to]30-500 m; width [almost equal to]2-15 m) are hosted by the serpentinite-peridotite unit. Unaltered chromites from massive chromitites (>80 % modal chromite) of the Byrapur and Bhaktarhalli chromite mines in the greenstone belt are characterized by high Cr# (100Cr/(Cr + Al)) of 78-86 and moderate Mg# (100 Mg/(Mg + Fe.sup.2+)) of 45-55. In situ trace-element analysis (LA-ICPMS) of unaltered chromites indicates that the parental magma of the chromitite ore-bodies was a komatiite lacking nickel-sulfide mineralization. In the Ga/Fe.sup.3+# versus Ti/Fe.sup.3+# diagram, the Byrapur chromites plot in the field of suprasubduction zone (SSZ) chromites while those from Bhaktarhalli lie in the MOR field. The above results corroborate our previous results based on major-element characteristics of the chromites, where the calculated parental melt of the Byrapur chromites was komatiitic to komatiitic basalt, and the Bhaktarhalli chromite was derived from Archean high-Mg basalt. The major-element chromite data hinted at the possibility of a SSZ environment existing in the Archean. Altered and compositionally zoned chromite grains in our study show a decrease in Ga, V, Co, Zn, Mn and enrichments of Ni and Ti in the ferritchromit rims. Trace-element heterogeneity in the altered chromites is attributed to serpentinization. The trace-element patterns of magnetite from the massive magnetite bands in the greenstone belt are similar to those from magmatic Fe-Ti-V-rich magnetite bands in layered intrusions, and magnetites from andesitic melts, suggesting that magnetite crystallized from an evolved gabbroic melt. Enrichments of Ni, Co, Te, As and Bi in disseminated millerite and niccolite occurring within chromitites, and in disseminated bravoite within magnetites, reflect element mobility during serpentinization. Monosulfide solid solution inclusions within pyroxenes (altered to actinolite) in pyroxenite, and interstitial pyrites and chalcopyrites in magnetite, retain primary characteristics except for Fe-enrichment in chalcopyrite, probably due to sub-solidus re-equilibration with magnetite. Disseminated sulfides are depleted in platinum-group elements (PGE) due to late sulfide saturation and the PGE-depleted nature of the mantle source of the sill-like ultramafic-mafic plutonic rocks in the Nuggihalli greenstone belt. Electronic supplementary material The online version of this article (doi:10.1007/s00410-015-1148-1) contains supplementary material, which is available to authorized users., Author(s): Ria Mukherjee[sup.1] [sup.2] , Sisir K. Mondal[sup.1] [sup.4] , Jose M. Gonzalez-Jimenez[sup.3] [sup.5] , William L. Griffin[sup.3] , Norman J. Pearson[sup.3] , Suzanne Y. O'Reilly[sup.3] Author Affiliations: (1) PGE [...]

Episodic refertilization and metasomatism of depleted subcontinental lithospheric mantle (SCLM) is rarely revealed within a single orogenic peridotite. We have investigated the Shenglikou peridotite massif in the North Qaidam Orogen (NE Tibet, China) to understand its origin and secular re-enrichment history and possible links with global tectonism, using multiple chemical and isotopic techniques. The massif contains two main groups of rocks, one rich in olivine (Ol) and the other rich in pyroxene (Pyro). In situ Re-Os isotope analyses on sulfides and previous reported whole-rock Os data show the Shenglikou peridotite massif has an Archean origin. The Ol-rich group has Mg# up to 0.923, Al.sub.2O.sub.3 contents down to 0.55 wt%, low FeO contents, whole-rock HREE ~0.01-0.1 times chondritic values and high spinel Cr# (up to 0.71). Modeling suggests that the Ol-rich peridotites are residues after ~30-40 % melt extraction at ~1600-1500 °C and [less than or equal to]5 GPa. Mineral compositions, oxygen-isotope compositions ([delta].sup.18O.sub.V-SMOW = 5.7 ± 0.1 â°) and attainment of Hf-isotope internal equilibration at ~1.5-1.4 Ga with initial ratios similar to that of depleted convective mantle indicate that the Ol-rich group was refertilized by silicate melts derived from the depleted asthenosphere at ~1.5-1.4 Ga, corresponding to one phase in the breakup of the Columbia supercontinent. On the other hand, chemical compositions and Hf-O isotopic signatures of the pyroxene-rich rocks suggest a second refertilization superimposed on the Archean lithospheric mantle at ~700 Ma, coeval with the global extension that affected Rodinia. Both groups show metasomatism by fluids, sourced from subducting slabs during the early Paleozoic convergence between the Qaidam and Qilian blocks. This study shows that the episodic refertilization and metasomatism of depleted Archean SCLM, temporally linked to supercontinental cycles, can be revealed in a single orogenic peridotite, and suggests that continental extension and convergence play an important role in the destruction of cratonic keels. Electronic supplementary material The online version of this article (doi:10.1007/s00410-015-1126-7) contains supplementary material, which is available to authorized users., Author(s): Qing Xiong[sup.1] [sup.2] , William L. Griffin[sup.2] , Jian-Ping Zheng[sup.1] , Suzanne Y. O'Reilly[sup.2] , Norman J. Pearson[sup.2] Author Affiliations: (1) State Key Laboratory of Geological Processes and Mineral [...]

The behavior of nickel in the Earth's mantle is controlled by sulfide melt-olivine reaction. Prior to this study, experiments were carried out at low pressures with narrow range of Ni/Fe in sulfide melt. As the mantle becomes more reduced with depth, experiments at comparable conditions provide an assessment of the effect of pressure at low-oxygen fugacity conditions. In this study, we constrain the Fe-Ni composition of molten sulfide in the Earth's upper mantle via sulfide melt-olivine reaction experiments at 2 GPa, 1200 and 1400 °C, with sulfide melt [Formula omitted] (atomic ratio) ranging from 0 to 0.94. To verify the approach to equilibrium and to explore the effect of [Formula omitted] on Fe-Ni exchange between phases, four different suites of experiments were conducted, varying in their experimental geometry and initial composition. Effects of Ni secondary fluorescence on olivine analyses were corrected using the PENELOPE algorithm (Baró et al., Nucl Instrum Methods Phys Res B 100:31-46, 1995), 'zero time' experiments, and measurements before and after dissolution of surrounding sulfides. Oxygen fugacities in the experiments, estimated from the measured O contents of sulfide melts and from the compositions of coexisting olivines, were 3.0 ± 1.0 log units more reduced than the fayalite-magnetite-quartz (FMQ) buffer (suite 1, 2 and 3), and FMQ - 1 or more oxidized (suite 4). For the reduced (suites 1-3) experiments, Fe-Ni distribution coefficients [Formula omitted] are small, averaging 10.0 ± 5.7, with little variation as a function of total Ni content. More oxidized experiments (suite 4) give larger values of K.sub.D (21.1-25.2). Compared to previous determinations at 100 kPa, values of K.sub.D from this study are chiefly lower, in large part owing to the more reduced conditions of the experiments. The observed difference does not seem attributable to differences in temperature and pressure between experimental studies. It may be related in part to the effects of metal/sulfur ratio in sulfide melt. Application of these results to the composition of molten sulfide in peridotite indicates that compositions are intermediate in composition ( [Formula omitted] ~ 0.4-0.6) in the shallow mantle at 50 km, becomes more Ni rich with depth as the O content of the melt diminishes, reaching a maximum (0.6-0.7) at depths near 80-120 km, and then becomes more Fe rich in the deeper mantle where conditions are more reduced, approaching ( [Formula omitted] ~ 0.28) > 140 km depth. Because Ni-rich sulfide in the shallow upper mantle melts at lower temperature than more Fe-rich compositions, mantle sulfide is likely molten in much of the deep continental lithosphere, including regions of diamond formation., Author(s): Zhou Zhang [sup.1] , Anette von der Handt [sup.1] , Marc M. Hirschmann [sup.1] Author Affiliations: (Aff1) 0000000419368657, grid.17635.36, Department of Earth Sciences, University of Minnesota, , 150 Tate [...]

Byline: Galina P. Bulanova (1), Michael J. Walter (1), Chris B. Smith (1), Simon C. Kohn (1), Lora S. Armstrong (1), Jon Blundy (1), Luiz Gobbo (2) Keywords: Brazil; Collier 4 kimberlite; Sublithospheric diamonds; Inclusions; Carbon isotopes; Subduction; Carbonatite melt Abstract: We report on a suite of diamonds from the Cretaceous Collier 4 kimberlite pipe, Juina, Brazil, that are predominantly nitrogen-free type II crystals showing complex internal growth structures. Syngenetic mineral inclusions comprise calcium- and titanium-rich phases with perovskite stoichiometry, Ca-rich majoritic-garnet, clinopyroxene, olivine, TAPP phase, minerals with stoichiometries of CAS and K-hollandite phases, SiO.sub.2, FeO, native iron, low-Ni sulfides, and Ca--Mg-carbonate. We divide the diamonds into three groups on the basis of the carbon isotope compositions ([delt[a].sup.13]C) of diamond core zones. Group 1 diamonds have heavy, mantle-like [delt[a].sup.13]C (-5 to -10[per thousand]) with mineral inclusions indicating a transition zone origin from mafic protoliths. Group 2 diamonds have intermediate [delt[a].sup.13]C (-12 to -15[per thousand]), with inclusion compositions indicating crystallization from near-primary and differentiated carbonated melts derived from oceanic crust in the deep upper mantle or transition zone. A 206.sup.Pb/ [.sup.238]U age of 101 +- 7 Ma on a CaTiSi-perovskite inclusion (Group 2) is close to the kimberlite emplacement time (93.1 +- 1.5 Ma). Group 3 diamonds have extremely light [delt[a].sup.13]C (-25[per thousand]), and host inclusions have compositions akin to high-pressure--temperature phases expected to be stable in pelagic sediments subducted to transition zone depths. Collectively, the Collier 4 diamonds and their inclusions indicate multi-stage, polybaric growth histories in dynamically changing chemical environments. The young inclusion age, the ubiquitous chemical and isotopic characteristics indicative of subducted materials, and the regional tectonic history, suggest a model in which generation of sublithospheric diamonds and their inclusions, and the proto-kimberlite magmas, are related genetically, temporally and geographically to the interaction of subducted lithosphere and a Cretaceous plume. Author Affiliation: (1) Department of Earth Sciences, University of Bristol, Queen's Rd, Bristol, BS8 1RJ, UK (2) Rio Tinto Desenvolvimentos Minerais Ltda, Brasilia, Brazil Article History: Registration Date: 11/01/2010 Received Date: 04/06/2009 Accepted Date: 11/01/2010 Online Date: 07/02/2010 Article note: Communicated by M. W. Schmidt.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.03.021 Byline: TomaA Kohout (a)(b), Andrei Kosterov (c), Jakub Haloda (d), Patricie TA1/2cova (d), Radek ZboAil (e) Keywords: Comets; Magnetic fields; Meteorites Abstract: In this study we present a review of low-temperature magnetic properties of alabandite (Fe,Mn)S, daubreelite FeCr.sub.2S.sub.4, pyrrhotite Fe.sub.1- .sub.x S and troilite FeS updated with new experimental data. The results indicate that besides FeNi alloys mainly daubreelite with its Curie temperature T.sub.C [approximately equal to]150K and strong induced and remanent magnetizations may be a significant magnetic mineral in cold environments and may complement that of FeNi or even dominate magnetic properties of sulfide rich bodies at temperatures below T.sub.C . Comets are known to contain iron-bearing sulfides within dusty fraction and their surfaces are subject to temperature variations in the range of 100-200K down to the depth of several meters while the cometary interior is thermally stable at several tens of Kelvin which is within the temperature range where alabandite, daubreelite or troilite are 'magnetic'. Thus not only FeNi alloys, but also sulfides have to be considered in the interpretation of magnetic data from cometary objects such as will be delivered by Rosetta mission. Modeling indicates that magnetic interactions between cometary nucleus containing iron-bearing sulfides and interplanetary magnetic field would be difficult, but not impossible, to detect from orbit. Rosetta's Philae lander present on the surface would provide more reliable signal. Author Affiliation: (a) Institute of Geology, Academy of Sciences, Prague, Czech Republic (b) Department of Physics, University of Helsinki, 00014 Helsinki, Finland (c) Institute of Physics, St. Petersburg University, St. Petersburg, Russia (d) Czech Geological Survey, Prague, Czech Republic (e) Centre for Nanomaterial Research, Palacky University, Olomouc, Czech Republic Article History: Received 21 December 2009; Revised 15 February 2010; Accepted 15 March 2010

Byline: Claudio Marchesi (1,2), William L. Griffin (2), Carlos J. Garrido (3), Jean-Louis Bodinier (1), Suzanne Y. O'Reilly (2), Norman J. Pearson (2) Keywords: Subcontinental lithospheric mantle; Partial melting; Proterozoic; Re--Os isotopes; Sulfide; Ronda massif Abstract: The western part of the Ronda peridotite massif (Southern Spain) consists mainly of highly foliated spinel-peridotite tectonites and undeformed granular peridotites that are separated by a recrystallization front. The spinel tectonites are interpreted as volumes of ancient subcontinental lithospheric mantle and the granular peridotites as a portion of subcontinental lithospheric mantle that underwent partial melting and pervasive percolation of basaltic melts induced by Cenozoic asthenospheric upwelling. The Re--Os isotopic signature of sulfides from the granular domain and the recrystallization front mostly coincides with that of grains in the spinel tectonites. This indicates that the Re--Os radiometric system in sulfides was highly resistant to partial melting and percolation of melts induced by Cenozoic lithospheric thermal erosion. The Re--Os isotopic systematics of sulfides in the Ronda peridotites thus mostly conserve the geochemical memory of ancient magmatic events in the subcontinental lithospheric mantle. Os model ages record two Proterozoic melting episodes at ~1.6 to 1.8 and 1.2--1.4 Ga, respectively. The emplacement of the massif into the subcontinental lithospheric mantle probably coincided with one of these depletion events. A later metasomatic episode caused the precipitation of a new generation of sulfides at ~0.7 to 0.9 Ga. These Proterozoic Os model ages are consistent with results obtained for several mantle suites in Central/Western Europe and Northern Africa as well as with the Nd model ages of the continental crust of these regions. This suggests that the events recorded in mantle sulfides of the Ronda peridotites reflect different stages of generation of the continental crust in the ancient Gondwana supercontinent. Author Affiliation: (1) Geosciences Montpellier, UMR 5243, CC 60, CNRS-Universite Montpellier II, Place E. Bataillon, 34095, Montpellier, France (2) GEMOC ARC National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, Australia (3) Instituto Andaluz de Ciencias de la Tierra (IACT), CSIC-Universidad de Granada, Avenida Fuentenueva s/n, 18002, Granada, Spain Article History: Registration Date: 13/07/2009 Received Date: 02/02/2009 Accepted Date: 13/07/2009 Online Date: 14/08/2009 Article note: Communicated by J. Hoefs.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.07.014 Byline: William H. Farrand (a), Timothy D. Glotch (b), James W. Rice (c), Joel A. Hurowitz (d), Gregg A. Swayze (e) Keywords: Mars; Mars, Surface; Mineralogy; Spectroscopy Abstract: Analysis of visible to near infrared reflectance data from the MRO CRISM hyperspectral imager has revealed the presence of an ovoid-shaped landform, approximately 3 by 5km in size, within the layered terrains surrounding the Mawrth Vallis outflow channel. This feature has spectral absorption features consistent with the presence of the ferric sulfate mineral jarosite, specifically a K-bearing jarosite (KFe.sub.3(SO.sub.4).sub.2(OH).sub.6). Terrestrial jarosite is formed through the oxidation of iron sulfides in acidic environments or from basaltic precursor minerals with the addition of sulfur. Previously identified phyllosilicates in the Mawrth Vallis layered terrains include a basal sequence of layers containing Fe-Mg smectites and an upper set of layers of hydrated silica and aluminous phyllosilicates. In terms of its fine scale morphology revealed by MRO HiRISE imagery, the jarosite-bearing unit has fracture patterns very similar to that observed in Fe-Mg smectite-bearing layers, but unlike that observed in the Al-bearing phyllosilicate unit. The ovoid-shaped landform is situated in an east-west bowl-shaped depression superposed on a north sloping surface. Spectra of the ovoid-shaped jarosite-bearing landform also display an anomalously high 600nm shoulder, which may be consistent with the presence of goethite and a 1.92[mu]m absorption which could indicate the presence of ferrihydrite. Goethite, jarosite, and ferrihydrite can be co-precipitated and/or form through transformation of schwertmannite, both processes generally occurring under low pH conditions (pH 2-4). To date, this location appears to be unique in the Mawrth Vallis region and could represent precipitation of jarosite in acidic, sulfur-rich ponded water during the waning stages of drying. Author Affiliation: (a) Space Science Institute, 4750 Walnut St., #205, Boulder, CO 80301, USA (b) Stony Brook University, Department of Geosciences, 255 Earth and Space Sciences Building, Stony Brook, NY 11794-2100, USA (c) Arizona State University, School of Earth and Space Exploration, P.O. Box 871404, Tempe, AZ 85287-6305, USA (d) Jet Propulsion Laboratory, Mail Stop 183-501, 4800 Oak Grove Drive, Pasadena, CA 91109, USA (e) U.S. Geological Survey, Box 25046, Denver Federal Center Mail Stop 964, Denver, CO 80225-0046, USA Article History: Received 20 March 2009; Revised 12 June 2009; Accepted 3 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.07.002 Byline: Elizabeth L. Podowski (a), Tom S. Moore (b), Kevin A. Zelnio (a), George W. Luther (b), Charles R. Fisher (a) Keywords: Hydrothermal vents; Community structure; GIS; In-situ voltammetry; Eastern Lau Spreading Center; Lau basin Abstract: Hydrothermal vent environments are characterized by large gradients of toxic chemicals and high temperatures, which play a significant role in defining species' distributions. We used high-resolution imagery and spatially explicit in-situ physico-chemical measurements analyzed within a Geographic Information System (GIS) in order to characterize the spatial relations among different groups of megafauna, temperature, and chemistry within two discrete vent communities (40 and 50m.sup.2) on the Eastern Lau Spreading Center (ELSC). Chemical (sulfide and O.sub.2 concentrations) and temperature data were obtained from approximately 75 different locations within each community using in-situ instruments. All data were integrated into a GIS, which served as a visualization tool and enabled the data to be analyzed in a spatial context. Our results confirm the importance of abiotic variables in defining the distributions of some fauna and elucidate several biological associations that are consistent between the two communities. The provannid snail, Alviniconcha spp., appears to actively avoid temperatures above 32-46[degrees]C and/or sulfide concentrations exceeding approximately 260[mu]M. Slightly higher average sulfide concentrations and temperatures were measured among aggregations of Ifremeria nautilei compared to aggregations of the mussel Bathymodiolus brevior; however, the presence of mixed aggregations of the two species indicates an overlap in requirements. The brachyuran crab, Austinograea spp., was consistently observed directly on symbiont-containing species, particularly Alviniconcha spp. The solitary snail, Eosipho desbruyeresi, was rarely observed on biological substrata, but was often (60% of its population at the most active site) within 5cm of symbiont-containing fauna, indicating a tolerance and preference for proximity to areas of high productivity. Densities and coverage of species differed substantially between the two communities despite high species overlap. Symbiont-containing species covered much larger areas at the more hydrothermally active site, ABE1, while shrimp and anemones occurred in relatively higher densities within the less-active site, TM1. This is the first study to thoroughly characterize realized distributions of megafauna at vent sites along the ELSC. Author Affiliation: (a) Biology Department, Pennsylvania State University, 208 Mueller Building, University Park, PA 16802, USA (b) College of Marine and Earth Studies, University of Delaware, 700 Pilottown Rd., Lewes, DE 19958, USA Article History: Received 28 January 2009; Revised 26 June 2009; Accepted 3 July 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2009.06.006 Byline: Daphne Cuvelier (a), Jozee Sarrazin (b), Ana Colaco (a), Jon Copley (c), Daniel Desbruyeres (b), Adrian G. Glover (d), Paul Tyler (c), Ricardo Serrao Santos (a) Keywords: Community structure; Spatial distribution; Faunal assemblages; Video analysis; Lucky Strike; Hydrothermal vent; Mid-Atlantic Ridge; Vent ecology Abstract: Whilst the fauna inhabiting hydrothermal vent structures in the Atlantic Ocean is reasonably well known, less is understood about the spatial distributions of the fauna in relation to abiotic and biotic factors. In this study, a major active hydrothermal edifice (Eiffel Tower, at 1690m depth) on the Lucky Strike vent field (Mid-Atlantic Ridge (MAR)) was investigated. Video transects were carried out by ROV Victor 6000 and complete image coverage was acquired. Four distinct assemblages, ranging from dense larger-sized Bathymodiolus mussel beds to smaller-sized mussel clumps and alvinocaridid shrimps, and two types of substrata were defined based on high definition photographs and video imagery. To evaluate spatial variation, faunal distribution was mapped in three dimensions. A high degree of patchiness characterizes this 11m high sulfide structure. The differences observed in assemblage and substratum distribution were related to habitat characteristics (fluid exits, depth and structure orientation). Gradients in community structure were observed, which coincided with an increasing distance from the fluid exits. A biological zonation model for the Eiffel Tower edifice was created in which faunal composition and distribution can be visually explained by the presence/absence of fluid exits. Author Affiliation: (a) IMAR/Department of Oceanography and Fisheries, University of the Azores, Cais de Santa Cruz, 9901-862 Horta, Portugal (b) Institut Francais de Recherche pour l'Exploitation de la Mer (Ifremer), Centre de Brest, Departement Etudes des Ecosystemes Profonds, Laboratoire Environnement Profond, BP 70, 29280 Plouzane, France (c) National Oceanography Centre, Southampton, University of Southampton Waterfront Campus, European Way, Southampton SO14 3ZH, UK (d) Zoology Department, The Natural History Museum, Cromwell Rd, London SW7 5BD, UK Article History: Received 28 November 2008; Revised 5 June 2009; Accepted 17 June 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.earscirev.2009.06.002 Byline: Karen A. Merritt (a), Aria Amirbahman (b) Keywords: mercury; methylation; estuary; marine; sediment Abstract: Considerable recent research has focused on methylmercury (MeHg) cycling within estuarine and coastal marine environments. Because MeHg represents a potent neurotoxin that may magnify in marine foodwebs, it is important to understand the mechanisms and environmental variables that drive or constrain methylation dynamics in these environments. This critical review article explores the mechanisms hypothesized to influence aqueous phase and sediment solid phase MeHg concentrations and depth-specific inorganic Hg (II) (Hg.sub.i) methylation rates (MMR) within estuarine and coastal marine environments, and discusses issues of terminology or methodology that complicate mechanism-oriented interpretation of field and laboratory data. Mechanisms discussed in this review article include: 1) the metabolic activity of sulfate reducing bacteria (SRB), the microbial group thought to dominate mercury methylation in these environments; 2) the role that Hg.sub.i concentration and/or speciation play in defining depth-specific Hg.sub.i methylation rates; and 3) the depth-dependent balance between MeHg production and consumption within the sedimentary environment. As discussed in this critical review article, the hypothesis of SRB community control on the Hg.sub.i methylation rate in estuarine and coastal marine environments is broadly supported by the literature. Although Hg.sub.i speciation, as a function of porewater inorganic sulfide and/or dissolved organic matter concentration and/or pH, may also play a role in observed variations in MMR, the nature and function of the controlling ligand(s) has not yet been adequately defined. Furthermore, although it is generally recognized that the processes responsible for MeHg production and consumption overlap spatially and/or kinetically in the sedimentary environment, and likely dictate the extent to which MeHg accumulates in the aqueous and/or sediment solid phase, this conceptual interpretation requires refinement, and would benefit greatly from the application of kinetic modeling. Author Affiliation: (a) ENVIRON International Corp. 136 Commercial St. Portland, ME 04101, USA (b) Department of Civil and Environmental Engineering, 5711 Boardman Hall, University of Maine, Orono, ME 04469, USA Article History: Received 5 January 2008; Accepted 18 June 2009

Byline: Sonja Aulbach (1), Steven B. Shirey (2), Thomas Stachel (1), Steven Creighton (1), Karlis Muehlenbachs (1), Jeff W. Harris (3) Keywords: Diamond; Sulfide; Inclusion; Eclogite; Peridotite; Re--Os; Isotope; Jagersfontein; Craton Abstract: Sulfide inclusions in diamonds from the 90-Ma Jagersfontein kimberlite, intruded into the southern margin of the Kaapvaal Craton, were analyzed for their Re--Os isotope systematics to constrain the ages and petrogenesis of their host diamonds. The latter have [delt[a].sup.13]C ranging between -3.5 and -9.8[per thousand] and nitrogen aggregation states (from pure Type IaA up to 51% total N as B centers) corresponding to time/temperature history deep within the subcontinental lithospheric mantle. Most sulfides are Ni-poor ([Ni + Co]/Fe = 0.05--0.25 for 15 of 17 inclusions), have elevated Cu/[Fe + Ni + Co] ratios (0.02--0.36) and elemental Re--Os ratios between 0.5 and 46 (12 of 14 inclusions) typical of eclogitic to more pyroxenitic mantle sources. Re--Os isotope systematics indicate two generations of diamonds: (1) those on a 1.7 Ga age array with initial 187.sup.Os/ [.sup.188]Os [(.sup.187]Os/ [.sup.188]Os.sub.i) of 0.46 +- 0.07 and (2) those on a 1.1 Ga array with 187.sup.Os/ [.sup.188]Os.sub.i of 0.30 +- 0.11. The radiogenic initial Os isotopic composition for both generations of diamond suggests that components with high time-integrated Re--Os are involved, potentially by remobilization of ancient subducted oceanic crust and hybridization of peridotite. A single sulfide with higher Os and Ni content but significantly lower 187.sup.Os/ [.sup.188]Os hosted in a diamond with less aggregated N may represent part of a late generation of peridotitic diamonds. The paucity of peridotitic sulfide inclusions in diamonds from Jagersfontein and other kimberlites from the Kaapvaal craton contrasts with an overall high relative abundance of diamonds with peridotitic silicate inclusions. This may relate to extreme depletion and sulfur exhaustion during formation of the Kaapvaal cratonic root, with the consequence that in peridotites, sulfide-included diamonds could only form during later re-introduction of sulfur. Author Affiliation: (1) Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada (2) Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC, USA (3) Department of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK Article History: Registration Date: 06/10/2008 Received Date: 29/04/2008 Accepted Date: 06/10/2008 Online Date: 06/11/2008 Article note: Communicated by J. Hoefs.

Byline: Victor Kress (1), Lori E. Greene (1,2), Matthew D. Ortiz (1,3), Luke Mioduszewski (1,4) Keywords: Sulfide; Liquid; Density; Thermodynamic model; Experimental; Partial molar volume Abstract: We present the results of a series of density experiments in the system O--S--Fe--Ni--Cu. These experiments were designed to extend our understanding of the physical properties of sulfide liquids, and to extend one-bar thermochemical models for sulfide liquids to apply to low to moderate pressures. Density measurements indicate both positive and negative deviations from linear mixing of partial molar volumes across this five-dimensional composition space. In terms of the homogeneous speciation model of Kress (in Contrib Mineral Petrol 154:191--204, 2007), the best fit to experimental data can be achieved by starting with a model where the volume of formation reaction for associated species initially is set to zero. Further refinement of this first-order fit yields a volume mixing model which reproduces experimental data to within nearly the estimated experimental uncertainty. Experimental ultrasonic and X-ray absorption data from the literature, along with the bulk modulus--volume relation of Anderson and Nafe (J Geophys Res 16:3951--3963, 1965), allow the estimation of the pressure dependence of partial molar volumes for sulfide liquid species. The resulting combined thermochemical model should be valid to about 2,000 K and 3 GPa. Application of this thermochemical model in a simple adiabatic magma ascent scenario confirms earlier work suggesting that the pressure dependence of sulfur solubility in sulfide-saturated magma will decrease with increasing pressure along geologically reasonable paths in P--T-- f.sub. O.sub.2 -- f.sub. S.sub.2 space. Author Affiliation: (1) University of Washington Earth and Space Sciences, Box 351310, Seattle, WA, USA (2) National Renewable Energy Laboratory, Golden, CO, 80401, USA (3) 9428 NE 146th Circle Apt C102, Bothell, WA, 98011, USA (4) 6504 34th Ave. NE, Seattle, WA, 98115, USA Article History: Registration Date: 24/05/2008 Received Date: 31/01/2008 Accepted Date: 23/05/2008 Online Date: 13/06/2008 Article note: Communicated by T. L. Grove.

We report sulfur isotopic compositions of sulfides of various paragenetic stages in the giant Sukhoi Log sediment-hosted orogenic Au deposit in Russia. The overall mean value and the significant variability in early pyrite indicate that the sulfur was from the reduction of seawater sulfate. The later generations of sulfide have [[delta].sup.34]S values in successively smaller ranges, coincident with the mode that is around the median value of the whole data set. Together with textural evidence, sulfide trace element data, and gold occurrence, the data demonstrate that metamorphism has gradually homogenized the early sulfur, accompanied by the segregation of quartz and the release of Au from the lattice of early pyrite and its reprecipitation as inclusions in later pyrite. The S isotopic compositions of sulfides in Sukhoi Log, and many other major orogenic Au deposits hosted in sedimentary rocks of various ages, show a pattern generally parallel to the seawater sulfate curve through geologic time, indicating that the sulfur in most sediment-hosted orogenic Au deposits was probably also originally from the reduction of seawater sulfate. We conclude that sulfidation and gold mineralization in many sediment-hosted orogenic gold deposits was early during basin evolution when seawater was the principal active fluid, rather than later, during or after basin inversion, as proposed in current models.

Byline: Alan E. Boudreau (1) Keywords: Bushveld Complex; Merensky Reef; Platinum group elements; Geochemical modeling Abstract: The Merensky pegmatoid (normal reef) in the western Bushveld Complex is commonly characterized as a pyroxene-rich pegmatoidal unit with a base that is enriched in chromite and platinum-group element-bearing sulfides overlying a leuconorite footwall. Models for its formation have ranged from those that view it as entirely a magmatic cumulate succession to those that have suggested that it is a zone of volatile-induced remelting. The consequences of the latter interpretation are investigated using the numerical modeling program IRIDIUM, which links diffusive and advective mass and heat transport with a phase equilibration routine based on the MELTS program. The initial system consists of a simple stratigraphic succession of a partially molten leuconorite overlain by a partially molten pyroxenite, both initially at 1,190degC and 2 kbar. 2 wt% of a volatile fluid composed of 75 mol% [H.sub.2]O, 20 mol% C[O.sub.2 ]and 5 mol% [H.sub.2]S is then added to the lower 20 cm of the pyroxenite. The system is then allowed to evolve under conditions of chemical diffusion in the liquid. The addition of the volatile components results in a modest increase in the amount of melt in the pyroxenite. However, chemical diffusion across the leuconorite--pyroxenite boundary leads to more extensive melting at and below the boundary with preferential loss of opx from the underlying leuconorite, preferential re-precipitation of sulfide and chromite and concentration of the PGE at this boundary. These results mimic actual mineral and compositional profiles across the Merensky pegmatoid and illustrate that long-term diffusion process can effectively produce mineralogical and compositional layering not present in the original assemblage. Author Affiliation: (1) Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA Article History: Registration Date: 27/02/2008 Received Date: 14/09/2007 Accepted Date: 27/02/2008 Online Date: 18/03/2008 Article note: Communicated by C. Ballhaus.

Byline: Sarah-Jane Barnes (1), R. A. Cox (1), M. L. Zientek (2) Abstract: Concentrations of Ag, Au, Cd, Co, Re, Zn and Platinum-group elements (PGE) have been determined in sulfide minerals from zoned sulfide droplets of the Noril'sk 1 Medvezky Creek Mine. The aims of the study were to establish whether these elements are located in the major sulfide minerals (pentlandite, pyrrhotite, chalcopyrite and cubanite), to establish whether the elements show a preference for a particular sulfide mineral and to investigate the model, which suggests that the zonation in the droplets is caused by the crystal fractionation of monosulfide solid solution (mss). Nickel, Cu, Ag, Re, Os, Ir, Ru, Rh and Pd, were found to be largely located in the major sulfide minerals. In contrast, less than 25% of the Au, Cd, Pt and Zn in the rock was found to be present in these sulfides. Osmium, Ir, Ru, Rh and Re were found to be concentrated in pyrrhotite and pentlandite. Palladium and Co was found to be concentrated in pentlandite. Silver, Cd and Zn concentrations are highest in chalcopyrite and cubanite. Gold and platinum showed no preference for any of the major sulfide minerals. The enrichment of Os, Ir, Ru, Rh and Re in pyrrhotite and pentlandite (exsolution products of mss) and the low levels of these elements in the cubanite and chalcopyrite (exsolution products of intermediate solid solution, iss) support the mss crystal fractionation model, because Os, Ir, Ru, Rh and Re are compatible with mss. The enrichment of Ag, Cd and Zn in chalcopyrite and cubanite also supports the mss fractionation model these minerals are derived from the fractionated liquid and these elements are incompatible with mss and thus should be enriched in the fractionated liquid. Gold and Pt do not partition into either iss or mss and become sufficiently enriched in the final fractionated liquid to crystallize among the iss and mss grains as tellurides, bismithides and alloys. During pentlandite exsolution Pd appears to have diffused from the Cu-rich portion of the droplet into pentlandite. Author Affiliation: (1) Sciences de la Terre, Universite du Quebec a Chicoutimi, Quebec, QC, Canada, G7H 2B1 (2) U.S. Geological Survey, Spokane Office, Washington, WA, 99201, USA Article History: Registration Date: 03/04/2006 Received Date: 03/10/2005 Accepted Date: 25/03/2006 Online Date: 31/05/2006 Article note: Communicated by T. L. Grove

The transformation of pentlandite, [(Ni,Fe).sub.9][S.sub.8], to violarite, [(Ni,Fe).sub.3][S.sub.4], has been investigated under mild hydrothermal conditions, at constant values of pH (range 3 to 5) controlled by the acetic acid/sodium acetate buffer. At 80 [degrees]C, 20(4) wt% of the pentlandite transforms to violarite in 33 days; with the addition of small amounts of [Fe.sup.3+][(C[H.sub.3]COO).sub.2](OH) and [H.sub.2]S the reaction reaches 40(4) wt% completion in this time. At 120 [degrees]C and a pressure of 3.5 bars the reaction is complete in 3 days at pH 3.9. Electron backscatter diffraction and backscattered electron imaging reveal that the reaction textures are typical of a coupled dissolution-reprecipitation reaction, rather than a solid state electrolytic process as has been previously reported. The gap between the dissolution front and the precipitation front of violarite is less than 400 nm. The violarite produced by these hydrothermal transformations is texturally similar to supergene violarite, being fine grained, porous and finely cracked. Keywords: Transformation, replacement reactions, pentlandite, sulfides, violarite

Results demonstrate that a positive charge increase on the sulfur, following nucleophilic attack of the sulfide, occurs during the transition state oxidation of aryl sulfides by peroxymonocarbonate ion. Data further reveal that the reaction is pH dependent with a pK(sub)a of approximately 1.6 for peroxymonocarbonate.

Research describes the syntheses, reaction kinetics, and oxidations of sulfides to sulfoxides brought about by chiral nonracemic 3-substituted-1,2-benzisothiazole 1,1-dioxides in the presence of hydrogen peroxide as an oxidant.

Research shows that sulfide-borane complexation increases from thioanisole to dimethyl sulfide with ether, sulfides, and dialkyl sulfides in between and in that order. However, the reactivity of the borane adducts toward 1-octene increases in the reversed order. Data suggest that the dialkyl sulfides are useful as borane and chloroborane carriers.

Results suggest that the ligand nature influences the mechanism of oxidation of organic sulfides to sulfoxides with four oxo(salen)chromium(V)[O=Cr(sup)v(salen) complexes in acetonitrile. Data indicate that overall the selective oxidation reaction is second-order and first-order each in the oxidant and the substrate.

Research has been conducted on the bacterial strains CVO abd FWKO B. The isolation of these strains from the oil field brine has been carried out.

Research has been conducted on the human lysozyme disulfide bonds. The effect of the disulfide bond on the human lysozyme structure, folding and stability has been studied.

Research has been conducted on the posttranslational glycosylation. The application of the top-down mass spectrometry characterization to the disulfide-bonded homodimers has been examined.

Research has been conducted on the oxidation of organic disulfides containing alkyl and aryl substituents by hydrogen peroxide. Conversion of thiosulfinate into thiosulfonate is described.