No description available.

Determination of water masses and circulation in the eastern Great Australian Bight, in conjunction with analysis of δ18O values and trace element concentrations in the articulated brachiopod Anakinetica cumingi, indicate that brachiopods faithfully record ambient temperatures and oceanographic conditions. Five water masses are identified on the shelf during March 1998, on the basis of temperature, salinity, δ2H and δ18O values. The warm, high salinity Great Australian Bight Plume occurs in the western part of the study area both at the surface and at depth, and the cool, low salinity Flinders Current flows west along the continental slope. The Flinders Current provides upwelling water along the Eyre Peninsula and in the central Great Australian Bight, and mixing of this water with Great Australian Bight Plume and shelf waters forms the combined water masses Flinders Current + Great Australian Bight outflow, Modified Flinders Current and Mixed waters. The Great Australian Bight Plume and Flinders Current are isotopically distinct, with Great Australian Bight Plume waters having lower δ18O values and higher δ2H values than Flinders Current waters. Using mean annual temperatures and δ18O values of seawater, brachiopod temperatures calculated from their δ18O values are within 1°C of measured temperatures. δ18O values in the brachiopods, in conjunction with seasonally variable temperatures and δ18O values of seawater, provide evidence for brachiopod major growth periods. Calculated brachiopod temperatures are most accurate assuming 70% of brachiopod growth occurs during summer when upwelling is occurring and 30% of growth occurs during the rest of the year. Brachiopods may be growing more during upwelling periods in response to increased food supply. Ba, Ni and V concentrations in the brachiopod shells show spatial variation that matches with water mass distribution on the shelf. Ba positively correlates with nitrate contents in the water and is enriched in brachiopods growing in upwelling areas. Ni and V positively correlate with seawater temperatures, suggesting that incorporation of these two elements into brachiopod calcite is temperature dependant. All three elements reflect the anticlockwise circulation pattern present in the eastern Great Australian Bight during the summer major growth period. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2009-01-29 16:23:44.036

The Paleoproterozoic Talbot volcanogenic massive sulphide (VMS) Cu-Zn occurrence is located near Talbot Lake, Manitoba, about 80 km south of Snow Lake. The mineralised system is unconformably overlain by more than 100 m of Paleozoic dolomite sequences and Quaternary glacial till. The clay fraction of the till contains pronounced anomalies of Zn, Cu, Ag, Pb, Au, Mn, Hg, Cd, Co, Bi and Se, which is ascribed to the formation of clay-humic complexes that have carbon-isotopic compositions of δ13C < -20‰. A VMS origin of the near-surface anomaly is confirmed by distinctly low 206Pb/204Pb ratios, compared to a more radiogenic till signature. The overall low 206Pb/204Pb ratios in the organic surface media black spruce bark, moss and humus also indicate input from a magmatic sulphide source, but likely reflect windblown material from the Flin Flon smelter stack at 160 km to the northwest. Black spruce tree rings that pre-date industrial sources of atmospheric metal input are used to measure historical element distributions because they record the local geochemistry at the time of heartwood growth and their root systems tap into large volumes of soil. At the Talbot prospect, the presence of secondary Zn from the till in black spruce tree cores is reflected in the Zn/Ca ratio, which eliminates the effect of dolomite-derived Zn. The process of element migration from buried mineralisation to the surface is complex and includes oxidation of sulphides, mobilisation and complexation of metal ions, physical upward transport, and deposition of indicator elements near the surface in accessible sampling media. To account for a significant influx of indicator elements into the relatively recently deposited till blanket, post-glacial groundwater upwelling is proposed to act as a major mechanism driving upward element migration. / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2011-05-14 04:38:36.886

Elevated arsenic (As) concentrations in surface water from storing mine tailings in lakes can have a negative impact on local and downstream vegetation and aquatic life. At Terra Mine, an abandoned silver and copper mine in the Northwest Territories, tailings storage in Ho-Hum Lake has resulted in dissolved As concentrations of 50-80 μg/L, exceeding the 5 μg/L maximum guideline for aquatic life. A natural wetland located downstream appears to be attenuating As from surface water. The objectives of this study was to understand the sources of As to the wetland, the effectiveness of the wetland to sequester As, the form and stability of As in the sediments, the processes controlling As mobility, and the effect of seasonal changes in the wetland in the dissolved phase. Arsenic bound to the sediments was determined by analyzing for bulk composition, and As speciation and element association were identified using synchrotron-based bulk XANES and ESEM analysis. Arsenic enters the wetland by surface flow from Ho-Hum Lake, subsurface flow through the waste rock airstrip, and by windblown dust. In spring, dissolved As concentrations in surface water increased downstream. In late summer, a decrease in concentration was observed in the upstream portion of the wetland, however As returned to lake concentrations further downstream. Sediment As concentrations increased over the summer. ESEM and bulk XANES indicate that As was associated with (oxy)hydroxides and secondary sulphides. In the spring, when water levels were high from snow melt, (oxy)hydroxides formed and captured As, while sulphide oxidation in the sediments lead to the release of As into surface water. Over the summer, the onset of reducing conditions from microbial activity drove the formation of As-bearing sulphides and dissolution of (oxy)hydroxides. While As was accumulating in the sediments at most sites in the wetland over the summer, these results suggest that the wetland was not effectively sequestering dissolved As from the surface water, and that sediment-water cycling of As in the wetland as a result of seasonal redox variations were contributing As in the surface water. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2011-06-24 12:46:26.649

The Goldstrike property, located in northern Nevada within the Carlin Trend, contains one of the largest Carlin-type Au deposits in the world. The vast majority of this mineralization, formed in the Eocene, is in the form of Au-bearing, trace element-rich arsenian pyrite, either as very fine grains, overgrowths on earlier pyrite, or as reported in this study, patchy zones with high As values. Eight samples characteristic of Ore I and Ore II - ore types defined by Almeida et al. (2010) - were selected and analysed using electron microprobe, secondary ion mass spectrometry, and synchrotron !-XRF. !-XRF is a non-destructive technique for the elemental analysis of these samples with additional structural analysis capability. Although Ore I and Ore II yield similar Au values in whole rock analyses, and in the samples selected in this study, Ore II yielded much lower Au and trace element values in pyrite than Ore I. However, free gold was found in an Ore II sample, which explained their similar gold grade in whole rock. Two compositional trends were identified based on the ratio of Au and As in auriferous pyrite from both Ore I and Ore II: 1) those above an Au/As ratio of 0.007, characterized by elevated Ag, Au, As, Cu, Hg, Sb, and Tl that trend positively with respect to Au. The maximum value of Au ranges from 0.12 to 0.15at% (0.56 to 0.68wt%), occurring at an As concentration of 2.5 to 4.3at% (5 to 7.4wt%), and 2) those below an Au/As ratio of 0.007, characterized by As above the optimal range associated with lower Au and lower trace element concentrations. The peak in As corresponds well with the theoretical maximum amount of As that can be incorporated as a solid solution in pyrite (~6wt%) before the structure changes to a two-phase pyrite-arsenopyrite system. The less structurally stable solid solution has a more reactive surface that is more amenable to adsorption of other trace elements, including Au, especially with increased As. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2012-08-27 14:03:12.542

Adsorption of the scale inhibitor, Diethylenetriaminepenta (methylenephosphonic) acid, DTPMP, on illite, kaolinite, Na-montmorillonite, and aluminum oxide was evaluated as a function of equilibrium concentration at constant temperature, pH and ionic strength. The experimental conditions used were typical of oil and gas formations, including a high ionic strength and moderate hardness. The work was done to quantify DTPMP adsorption on common subsurface materials, and compare DTPMP adsorption to ortho-phosphate, a well studied, strongly adsorbing oxyanion. The experimental results showed that DTPMP adsorbed strongly to these surfaces, and suggested that adsorption was by ligand exchange. Adsorption on aluminum oxide and illite was especially high at low concentrations. This suggested bi-dentate adsorption at high energy surface sites and ternary adsorption on exchangeable polyvalent metals. The calculated DTPMP adsorption isotherms were consistent with isotherms describing ortho-phosphate adsorption, and successfully predicted adsorption curves on soils of known composition. Simulated 1-D column breakthrough curves, based upon DTPMP adsorption isotherms, varied from reported experimental curves. This was due to the non-equilibrium conditions which existed during the column studies.

Fundamental aspects of the surface chemistry of calcite, dolomite, magnesite, and gaspeite in aqueous solutions were examined using different lines of investigation including experimental, theoretical, and/or computer-assisted modeling approaches (i.e., ab initio molecular and surface complexation modeling). A Genetic Algorithm (GA) was implemented and tested for the calibration of surface complexation models (SCMs). The GA can successfully optimize numerous adjustable SCM parameters without incurring convergence problems while minimizing numerical instability problems, a notable advantage over conventional deterministic, root-finding, and optimization techniques implemented in codes such as FITEQL. It was routinely used throughout this thesis for the simultaneous calibration of surface complexation parameters (e.g., intrinsic constants, capacitances) at carbonate surfaces. The definition of reactive surface sites at hydrated rhombohedral carbonate mineral surfaces was critically revisited. Using calcite as the model mineral, a single generic charge-neutral surface site scheme was proposed for the formulation of surface equilibria. The resulting molecular representation of surface equilibria is consistent with experimental and theoretical findings and is compatible with assumptions implicit in SCMs. Based upon the one-site scheme, new and simplified SCMs for magnesite and dolomite were formulated. These successfully reproduced published surface charge and electrokinetic data while yielding surface speciation predictions consistent with available spectroscopic data. The acid-base behavior of the gaspeite (NiCO3(s)) surface in NaCl solutions was investigated for the first time by means of conventional titration techniques and micro-electrophoresis. Surface protonation and the electrophoretic mobility of gaspeite are strongly affected by the background electrolyte. Acid-base surface complexation reactions, / Des aspects fondamentaux sur la chimie surfacique des minéraux carbonatés dans des solutions aqueuses ont été examinés par des approches expérimentales et théoriques ainsi que par des méthodes d'optimisation numérique et de modélisation moléculaire.Un algorithme génétique (GA, selon son sigle anglais) a été implémenté et testé pour la calibration de modèles de complexation à la surface (SCMs, selon son sigle anglais). Le GA peut optimiser de façon stochastique et simultanée des nombreux paramètres tout en minimisant des problèmes de convergence ou de stabilité numérique. Cet algorithme est très avantageux par rapport aux techniques déterministiques conventionnelles adoptées par des codes d'optimisation de constantes d'équilibre tel que FITEQL. Le GA a donc été utilisé de façon routinière dans cette étude, pour estimer les constantes de formation des espèces chimiques se formant à la surface des minéraux carbonatés. En utilisant la calcite comme modèle, nous avons réévalué de façon critique la définition de sites réactifs à la surface hydratée des minéraux carbonatés rhomboédriques. Ceci nous a permis de définir un site d'adsorption générique neutre pour ce type de minéraux, qui est compatible avec les résultats d'études théoriques et expérimentales ainsi qu'avec des hypothèses associées à la formulation de SCMs. Des nouvelles réactions, basées sur un seul site générique, ont été formulées pour la magnésite et dolomite et calibrées en utilisant des données publiées de charge surfacique et, par la suite, testées avec des données électrocinétiques et spectroscopiques disponibles dans la littérature.Le comportement acide-base à la surface de la gaspéite (NiCO3(s)), dans des solutions de NaCl, à été examiné par des techniques conventionnelles de titrage surfacique et par la micro-électrophorèse. Nous avons trouvé que l'él

The sulphur isotopic evolution of basaltic melts degassed under disequilibrium conditions was investigated experimentally at temperatures of 1225 oC and oxygen fugacities between 0.5 and 1.9 log10 units above that defined by the Ni-NiO buffer. Melts were equilibrated at a pressure of 550 MPa in a piston-cylinder apparatus and degassed at ~490 to 0 MPa. Water concentrations in the experimental glasses varied from 1.5-10 wt %. Extents of degassing were quantified by comparing sulphur concentrations in the experimentally degassed (DG) glasses to those in isobarically quenched (IQ) glasses, and ranged from 0 to ~40%. Degassed glasses were systematically more enriched in 34S than IQ glasses, and the degree of enrichment correlated positively with the extent of degassing. Predicted fractionation factors between the gas and the melt (34αg-m) for open-system degassing under conditions of local gas-melt equilibrium ranged from 0.9986 to 0.9996. Our empirical fractionation factor was found to be 0.9987, which lies near the low end of the predicted range, suggesting that another process is contributing to S isotope fractionation. Modelling results indicate that a possible explanation for this behaviour is the diffusion of S during bubble growth; however consideration of the mechanistic details of bubble growth show that more sophisticated models than those employed in this study are needed to fully quantify this effect. / Une investigation de l'evolution isotopique du soufre dans les liquides basaltiques a été effectuée à une temperature de 1225 °C et à une fugacité d'oxygène entre 0.5 et 1.9 unités log10 au-dessus du tampon Ni-NiO. Les matières fondues ont été équilibrées à une pression de 550 MPa dans un appareil piston-cylindre et dégazées de ~490 à 0 MPa. Les concentrations de l'eau dans des verres expérimentaux ont varié entre 1.5 et 10 % (en masse). Le taux de dégazage (variable de 0 à ~40 %) a été quantifié en comparant les concentrations de soufre dans les verres dégazés experimentalement (DG) à celles de verres trempés de façon isobarique (IQ). Les verres DG étaient systématiquement plus enrichis en 34S que les verres IQ, et cet enrichissement montrait une corrélation positive avec le degré de dégazage observé. Les facteurs de fractionation théoriques entre la phase gazeuse et la phase fondue (34αg-m) pour dégazage d'un système ouvert sous conditions d'équilibre localisé (phase gazeuse-phase fondue) ont varié entre 0.9986 to 0.9996. Notre facteur de fractionation empirique était de 0.9987, vers le bas de la gamme prédite, ce qui suggère qu'un processus additionel contribue à la fractionation isotopique de soufre. Nos résultats de modélisation suggèrent la diffusion du soufre pendant la croissance de bulles de gaz comme possible explication; néanmoins, la prise en compte des détails mécanistiques de la croissance des bulles montre que des modèles plus complexes que ceux utilisés ici sont nécessaires pour une quantification complète de cet effet.

The solubility of Zr-bearing minerals in peralkaline, H2O-saturated alkali aluminosilicate melts with or without added F reaches a maximum of about 4 and 3.5 wt.% ZrO2 respectively at approximately 57 wt.% SiO2. The saturating phase for melts with SiO2 content above this threshold is zircon. In the halogen-free experiments, the saturating phase for melts with lower silica content is wadeite (K2ZrSi 3O9), while ZrO2 crystallizes from melts with 1 wt.% added F. Experiments with Cl-bearing melts indicate no maximum solubility of Zr minerals; the solubility remains at 2 to 2.2 wt.% ZrO2 across a wide compositional range. The saturating phases in the Cl-bearing melts are the same as those of the F-bearing melts and the transition from ZrO 2 to zircon occurs at the same composition. The positive slope of the wadeite saturation curve on XZrO2-XSiO2 plots for the halogen-free melts suggests that increasing SiO2 activity increases the solubility of wadeite. / Peralkaline Ti,Zr-bearing sodium aluminosilicate glasses have been analyzed by Raman spectroscopy to determine the effect of Cl on glass structure. The spectra of the Ti-bearing glasses show a significant difference between the Cl-free and the Cl-bearing composition. The Cl-free glass spectrum contains a strong, asymmetric peak at 900 cm--1 which is associated with Ti in five-fold coordination. This peak is shifted to higher frequency and becomes more symmetric with the addition of 0.3 wt.% Cl. Deconvolution of the high-frequency waveband suggests that differences between spectra result from the contribution of a peak at 945 cm--1. This peak is believed to be the result of Ti-O vibrations in fully-polymerized titanate tetrahedra. It is proposed that the addition of Cl destabilizes [5] Ti in favour of tetrahedral coordination as a result of competition between Cl and titanate groups for alkalis. / 23Na NMR MAS analyses of a suite of Na-aluminosilicate glasses with Na/Al = 2 and varying SiO2 content has revealed a trend toward more negative chemical shift (greater shielding of the nucleus) as the glass structure becomes more polymerized, i.e. the average number of non-bridging oxygen atoms per tetrahedron (NBO/T) decreases. This trend is observed only for glasses with NBO/T &le; 0.3. For more polymerized glasses no change in chemical shift is measured. (Abstract shortened by UMI.)

It is thought that a significant mechanism of stibnite (Sb2S3) oxidation in mine wastes is through contact with a mineral of greater rest potential (whereby the outer valence shell electrons operate at a higher energy level), such as pyrite (FeS2). The goal of this research is to determine if the oxidation of stibnite in an oxygenated flow through system was increased through contact with minerals of greater rest potential such as pyrite and arsenopyrite (FeAsS) and whether this electro-chemical reaction was affected by various ratios of stibnite to pyrite (or arsenopyrite) and slightly acidic (pH 5) to alkaline (7.5) pH conditions. Four column leaching experiments were carried out using various ratios of stibnite and pyrite (or arsenopyrite). When the two minerals were mixed in columns and leached with water, the treatment with the greatest amount of pyrite and least amount of stibnite (95% pyrite) had the highest cumulative amount of dissolved Sb (Exp #2- 16 730 mg Sb/kg stibnite). X-ray absorption near-edge structure (XANES) analysis of the solid phase revealed that the 95% pyrite treatment had the highest proportion of total Sb as Sb(V)-O species compared to all other mixed treatments and 100% stibnite. These results indicate that galvanic interactions had occurred between stibnite and pyrite. Using a solution buffered to pH 7.5, it was possible to determine the effect of a high pH environment on these galvanic interactions between stibnite and pyrite. Under slightly alkaline pH conditions, the 95% pyrite treatment had the highest cumulative amount of dissolved Sb (Exp #3- 18 090 mg Sb/kg stibnite) and this amount was similar to the 95% pyrite treatment in experiment #2. XANES analysis revealed a smaller proportion of total Sb as oxide species in this experiment compared to experiment #2, possibly due to the formation of a soluble Sb complex with HCO3-. In Experiment #4, the leaching with deionized water of a mixed system containing stibnite and arsenopyrite / On croit qu'un des mécanismes importants de dissolution de la stibnite (Sb₂S₃) dans les résidus miniers est par contact avec un minéral ayant un plus fort potentiel électrique, tel que la pyrite (FeS₂). L'objectif de la recherche était de déterminer l'impact du ratio stibnite vs. pyrite et l'effet du pH sur le taux de dissolution de la stibnite. Quatre essais de lessivage en colonnes ont été réalisés. Les deux premiers essais de lessivage avec de l'eau déionisée ont montré que le traitement contenant la plus forte proportion de pyrite (95% pyrite) a résulté en la plus grand quantité cumulative de Sb dissous (Exp #2-16730 mg Sb/kg stibnite). L'analyse spectroscopique par absorption des rayons-X (XANES) de la phase solide a révélé que la proportion de Sb total sous forme Sb(V)-O était plus importante dans le traitement 95% pyrite comparé à tous les autres traitements mixtes et au traitement contrôle de 100% stibnite. Ces observations indiquent que des interactions galvaniques ont eu lieu entre la stibnite et la pyrite. En utilisant une solution tamponnée à pH 7.5, il fut possible de déterminer l'effet d'un pH légèrement alcalin sur ces interactions entre la stibnite et la pyrite. Dans ces conditions, la quantité maximale de Sb dissous a été atteinte dans le traitement 95% pyrite (Exp #3-18090 mg Sb/kg stibnite), ce qui est comparable au traitement 95% pyrite dans l'expérience #2 de lessivage à l'eau. Cependant, l'analyse XANES a révélé une proportion moindre du Sb total sous forme d'oxide dans l'essai de lessivage à pH 7.5, possiblement en raison de la formation d'un complexe soluble entre Sb et HCO₃-. L'expérience #4 a testé l'impact de l'arsenopyrite sur la dissolution de la stibnite lors d'un lessivage à l'eau. Dans ce cas, le traitement 95% arsenopyrite (Exp #4-10311 mg Sb/kg stibnite) a libéré moins de Sb en solution comparé au traitement 95% pyrite de l'expérience #2, et ce résultat s'explique par la plus p