In this study, we report the experimentally-determined solubility of 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), and we derive a speciation-based model for estimating the solubilities of other chlorophenols. At 25$ sp circ$C, the log molality of the protonated species of 2,4,6 TCP is $-$2.8 $ pm$ 0.2, whereas for PCP the value is $-$5.1 $ pm$ 0.4. The pK$ rm sb{a}$ values that best fit the solubility data for 2,4,6 TCP and PCP are 6.0 $ pm$ 0.3 and 4.5 $ pm$ 0.5, respectively. At 55$ sp circ$C, the log molality of protonated PCP increases to $-$4.7 $ pm$ 0.2 and the pK$ rm sb{a}$ value decreases to 4.1 $ pm$ 0.3. Addition of a Na-chlorophenol aqueous species to the model improves the fit to each dataset and, at 25$ sp circ$C, we calculate log stability constants values for NaPCP$ sp circ$ and NaTCP$ sp circ$ of 1.1 $ pm$ 0.5 and 0.9 $ pm$ 0.4, respectively. At 55$ sp circ$C, the stability constant for NaPCP$ sp circ$ is 0.7 $ pm$ 0.4. The results of this study enable estimations of chlorophenol solubilities under a wide range of conditions of environmental interest.

A novel and simple "constant-addition" technique was used to study calcite precipitation kinetics and the partitioning of REE between calcite overgrowths and their parent seawater solutions under steady state conditions. / As a consequence of solute interactions in solution and at the growing mineral surface, the calcite precipitation mechanism in seawater is complex. It is dominated by the following reversible overall reaction: $ rm Ca sp{2+}+CO sbsp{3}{2-} rightleftharpoons CaCO sb3.$ A kinetic expression is proposed which describes the precipitation rate according to this reaction. A partial reaction order of 3 with respect to CO$ sb3 sp{2-}$ is obtained. / REE have a strong affinity for calcite and substitute for Ca$ sp{2+}$. REE partition coefficients in calcite overgrowths were calculated from their concentrations in the overgrowths and their parent solutions using a non-thermodynamic homogeneous model. The concentrations were determined by chelation and gradient ion chromatography (CGIC) using a revised procedure. REE partition coefficients decrease gradually with increasing REE atomic number. They are sensitive to changes in (REE): (Ca$ sp{2+}$) and the presence of O$ sb2$ in solution, but unaffected by the precipitation rate, $ rm lbrack CO sb3 sp{2-} rbrack$ or Pco$ sb2$ of the solution. The partitioning behaviour of REE is negatively correlated to the solubility of their respective carbonates and influenced by speciation, adsorption, and subsequent surface reactions (e.g., dehydration).

Stromboli volcano (Aeolian Islands, Italy) has two types of magma: volatile-rich, aphyric magma (LP) that produces pumices and volatile-poor, highly porphyritic magma (HP) that produces scoria. This work studies how changes of magma properties affect the bubble formation and growth, and the dynamics of volcano eruptions. The first part of this work is a study of bubble formation and growth in crystal-free Stromboli basalts. Using X-ray microtomography (µCT) I studied the 3-D bubble sizes and distributions, determined the permeability with lattice-Boltzmann simulations and laboratory measurements, investigated the factors that control the occurrence of Darcian and non-Darcian flow, and delineated the Darcian and non-Darcian flow regimes in the vesicular Stromboli basalts by constraining the correlations between friction factor (fk) and Forchheimer number (Fo). The second part of this work is based upon degassing experiments of crystal-bearing basalts at a synchrotron X-ray beamline. I studied 3-D crystal sizes and distributions, investigated the crystal effect on bubble sizes and distributions with X-ray µCT, and measured the magma permeability. The results demonstrate that the permeabilities of crystal-bearing Stromboli basalts are about 1 to 2 orders of magnitude higher than those in crystal-free samples in the porosity range of 31.6 to 55.3%. Based on my experimental results, I propose that the higher permeability in crystal-bearing samples results in highly efficient degassing in the shallow, highly porphyritic (HP) magma as opposed to the deeper, aphyric (LP) magma. The LP magma flows up in a cylindrical conduit due to the density and viscosity difference between the two magmas. We calculated the ascending LP magma volume flux and the descending HP magma volume flux, showing that LP magma can be efficiently transferred through the overlying HP magma, implying that this type of convection can potentially cause the more-violent paroxysmal explosions occasionally observed at Stromboli. / Le volcan Stromboli (îles Éoliennes, Italie) a deux types de magma: un magma aphyrique, riche en volatiles et produisant du pumice, et un magma hautement porphyritique produisant de la scorie. Cette étude documente l'influence de variations en propriétés magmatiques sur la formation et la croissance de bulles, et leur impact sur la dynamique des éruptions volcaniques. En première partie, la formation et la croissance des bulles a été étudiée dans les basaltes stromboliens sans cristaux. J'ai étudié par microtomographie en rayons-X la distribution tri-dimensionnelle et la taille des bulles dans ces basaltes vésiculés, quantifié leur perméabilité par des simulations de type Boltzmann sur réseau et par des mesures en laboratoire, investigué les facteurs qui contrôlent l'écoulement darcien et non-darcien, et délimité ces deux régimes en contraignant les corrélations entre le facteur de friction (fk) et le nombre Forchheimer (Fo). La deuxième partie est une étude expérimentale in situ sur une ligne synchrotron du dégazage de basaltes contenant des cristaux. La distribution tri-dimensionelle des cristaux et leur effet sur la taille des bulles et la perméabilité du magma ont été quantifiés par microtomographie rayons-X. Les valeurs de perméabilité des basaltes de Stromboli contenant des cristaux sont d'un à deux ordres de grandeur plus élevées que celles de basaltes sans cristaux, pour des valeurs de perméabilité allant de 31.6 à 55.3%. Ces résultats expérimentaux suggèrent que la perméabilité plus élevée des échantillons de basaltes contenant des cristaux favorise le dégazage des magmas hautement porphyritiques situés à faible profondeur, relatif aux magmas aphyriques et présents à plus grande profondeur. Le magma aphyrique remonte le long d'un conduit cylindrique à cause des différences de densité et viscosité entre les deux types de magmas. Des calculs de flux volumique d'un magma aphyrique ascendant et d'un magma porphyritique descendant démontrent que le magma aphyrique peut circuler efficacement et traverser un magma porphyritique sus-jacent. Ce type de convection pourrait potentiellement causer les éruptions paroxysmales observées sporadiquement à Stromboli.

The octanol-water partition coefficients (log Kow) of 2,4,6-trichlorophenol and pentachlorophenol were determined as functions of pH, ionic strength, and aqueous metal content. For both chlorophenols, the log Kow exhibits pH dependence in the range pKa-1 < pH < pK a+2. At lower and higher pH values, the Kow behaviour of the chlorophenols is independent of pH. Our data, in conjunction with those of Westall et al. (1985), indicate that a linear relationship exists Our data, in conjunction with those of Westall et al. (1985), indicate that a linear relationship exists between log Kow and log ionic strength of the aqueous solution for pentachlorophenol. Our results r results also suggest that aqueous metal-chlorophenol ate complexation can significantly alter the also suggest that aqueous metal-chlorophenolate complexation can significantly alter the partitioning behaviour. / We use our data to develop an empirical model of the partitioning behaviour based on speciation of the aqueous chlorophenol. The model requires knowledge of the low pH partitioning behaviour, as well as the acidity constant (pK a) of the chlorophenol of interest. Although Kow values have been measured as a function of pH and/or ionic strength for only pentachlorophenol, the input parameters for the empirical model are readily available in the literature for many chlorophenols. The model greatly expands our ability to quantify the hydrophobicity of chlorophenols, facilitating accurate estimations of the pH and ionic strength dependencies of the partitioning behaviour over a wide range of pH and ionic strength values of environmental interest.

The Thelon basin, Nunavut, is similar to the uranium-producing Athabasca Basin, Saskatchewan; however, the uranium deposits associated with the Thelon Basin are poorly understood. The objective of this research is to develop a genetic model for the Bong uranium deposit, located in the Northeast Thelon region on the Kiggavik project of AREVA Resources Canada Inc. The Bong deposit formed in four stages. The first stage involved silicification of the host rocks. Stage 2 is characterized by pervasive argillization of the host rock and the formation of Stage A uraninite in veins and coating graphite (~1120 Ma). This stage is characterized by ~225°C fluids with calculated δ18O and δD values of -7.9‰ and -100.9‰, respectively. During Stage 3, organic matter formed, along fractures in permeable clay-rich alteration zones. At ~1040 Ma, an oxidizing fluid event (Stage 4) reconcentrated uraninite into redox fronts (Stage B) and altered Stage A uraninite to uranophane.

The Red Lake greenstone belt is considered to be one of Canada’s premier gold producing regions with the Red Lake Gold Mines having produced >24 million ounces of gold to date. The East Bay Trend is a large structural corridor that parallels the East Bay of Red Lake, Ontario and is interpreted to be a manifestation of the regional D1 structure that crosscuts this complexly folded greenstone belt. The southernmost 8 km of this corridor is host to a variety of small gold deposits that demonstrate an assortment of mineralization styles. This study aims to: (1) better define veining styles and characterize the mineralizing fluids using petrography, fluid inclusions, geochronology and stable isotopes, (2) compare barren and auriferous veins from deposits along the East Bay Trend, and (3) compare the fluid history of the East Bay Trend to the Campbell-Red Lake gold deposit to determine the gold potential along this trend.

This dissertation aims to provide insight into the relationships between environmental factors and the organization of quartz technology in northern Manitoba by evaluating the contribution of large pegmatite quarries to quartz economies around Granville and Southern Indian Lakes. Secondary ion mass spectrometry (SIMS) quantification of trace element (Ti, Ge, U, Th) concentrations and Pb isotope ratios was used to characterize large sources of pegmatite quartz exploited by toolmakers in the Granville Lake and Lac La Ronge regions of northern Manitoba and Saskatchewan, respectively. The same technique was applied to a sample of formal quartz tools from the Churchill River Diversion Archaeological Project (CRDAP) study area in northern Manitoba. Quarry and artifact results were compared. The results of this analysis indicate: 1) characterized pegmatite quartz sources in the Granville Lake district likely played a significant role in quartz economies in the Churchill River basin of northern Manitoba, 2) toolmakers in the study area had large lithic procurement ranges, and 3) lithic resource stress contributed to the selection of technological strategies in the Churchill River basin.

The Millennium uranium deposit is located 35 km north of the Key Lake mine, Saskatchewan. Uranium mineralization occurs in a variety of styles including (1) massive replacement, (2) fracture filling veins, (3) fine-grain aggregates associated with “mini” roll fronts, and (4) disseminated grains. The chemical Pb and isotopic 207Pb/206Pb ages of the massive (style 1), vein-type (style 2), and fine-aggregate (style 3) uraninite cluster at 1400-1200 and 1100-900 Ma. The ~1400 Ma ages coincide with the primary mineralization event for many of the uranium deposits (1550-1400 Ma) within the Athabasca Basin. Unlike other uranium deposits from the Athabasca basin, disseminated uraninite (style 4) have 207Pb/206Pb ages from 1770-1650 Ma. These ages are older than the depositional age for the Athabasca sediments (~1710 Ma) and are similar to the ages from the Beaverlodge vein-type uranium deposits.

No description available.

The giant Pascua Au-Ag-Cu high-sulphidation system is located in the El Indio belt in north-central Chile, and is hosted mainly by Triassic granitic rocks and locally by Miocene breccia bodies. Hydrothermal activity involved two distinct high-sulphidation alteration stages, the later of which was accompanied by main stage mineralization. The early hydrothermal activity consisted of extensive and pervasive advanced argillic alteration, local development of vuggy silica and distal argillic to propylitic alteration. This alteration was locally overprinted by an intermediate stage comprising argillic alteration, silicification and primary jarosite, more or less contemporaneously with the formation of Brecha Central, the main breccia body in the deposit. The superimposed second major hydrothermal event produced significant advanced argillic and vuggy silica alteration. The latter likely formed at pH near 0 owing to the limited buffering capacity of previously altered rocks. Termination of the second stage of alteration coincided with the main Au-Ag-Cu mineralizing event, in which Au dissolved in pyrite and enargite, formed inclusions in these minerals, and precipitated as isolated grains of native gold. Detailed EPMA and SIMS imaging and analyses of pyrite and enargite show that both contain Au, Ag, As, Cu, Se and Te and that their distribution is crystallographically controlled. The main trace element associations in the mineralized pyrite are As-Ag, Au-Cu and Se-Te. I suggest that the first two, As-Ag and Au-Cu, were the result of coupled substitution in the Fe site, whereas Te and Se replace S by direct anion exchange. The nature of the coupled substitutions observed in the gold-bearing pyrite underlines the fact that gold is not necessarily coupled with arsenic as previously thought and that arsenic can behave as a metal in the structure of pyrite. Approximately 55% of the gold in the deposit was scavenged from mineralizing fluids that were mainly under-saturated with respect to native gold and trapped into the structure of pyrite and enargite (50 and 5%, respectively). The remaining 45%, including - 7% as inclusions in sulphides, precipitated mainly in the form of native gold with lesser calaverite for which the gold depositional mechanism is interpreted to be an increase in pH that destabilized AuHS and AuCb". Substantial late-stage Ag-enrichment, characterized by halogen-bearing phases, is evident in the upper parts of the deposit and overprints previous alteration and mineralization. The silver enrichment event is interpreted to represent the waning stage of the hydrothermal system. Secondary leaching and weathering of pyrite, enargite and alunite created two supergene products, one dominated by secondary soluble sulphates such as voltaite, massive coquimbite, chalcanthite, and romerite, and one by jarosite. Abundant sulphides in vuggy silica altered rocks, which lacked the capacity to neutralize later oxidizing fluids, were the main locus of formation of the soluble sulphates. Elsewhere, the pH likely rose above 1, which inhibited precipitation of soluble sulphates and favoured formation of jarosite. Direct-ion SIMS images and trace element analyses of soluble sulphates indicate that these minerals likely contain gold in their structures.