Twenty-one galena specimens from 16 mineral deposits in the Kootenay district analysed isotopically in replicate have a linear relationship of isotopic compositions on a Pb²º⁶/Pb²º⁴ versus Pb²º⁷/Pb²º⁴ graph. Twelve of the galenas, including two from Sullivan mine (East Kootenay district), were analysed by an intercomparison technique; the first application of the intercomparison method to an anomalous lead suite. Intercomparison results verify the linear compositional pattern (slope = 0.1084 ± 0.0033). These results indicate that: 1. Kootenay arc leads are multi-stage leads. 2. Sullivan-type lead is the parent common lead from which the anomalous suite developed. 3. Kootenay arc mineral deposits formed during one major mineralizing episode. Time of anomalous lead mineralization, tm, is probably Jurassic as deduced from potassium-argon dates and crosscutting relations of ores and igneous rocks. Assuming tm = 180 m.y. time of emplacement of uranium and thorium that produced the radiogenic component of the anomalous leads is approximately 1700 m.y., possibly the age of Lower Purcell strata of the East Kootenay district. Lead isotopic compositions show no obvious correlations with age of wallrock, type of wallrock, geological nature of ore deposits, or minor element content of galena. Post-ore thermal metamorphism and hydrothermal alteration do not appear to have changed lead isotopic compositions. The history of evolution of Kootenay arc anomalous leads is interpreted as follows: 1. Formation of source rocks containing uranium and thorium about 1700 m.y. ago. 2. Introduction of Sullivan-type lead into source rocks about 1340 m.y. ago. 3. Mixing of Sullivan-type lead with radiogenic lead formed by decay of uranium and thorium, and transportation and deposition of these "lead mixtures” to form anomalous lead deposits during Coast Range orogeny. Geologic and isotopic data from Sullivan mine are reconciled most easily with an epigenetic origin of the Sullivan orebody, and probably with a genetic relation of Sullivan ore fluids with the source magma of Moyie Intrusions. Holmes-Houtermans model age for Sullivan ore, based on intercomparison data, is 1340 m.y. Sullivan lead evolved in a source with U²³⁸/Pb²º⁴ = 9.02, Th²³²/Pb²º⁴ = 36.71, and Th/U = 4.07 (in terms of present day abundances). A method of estimating volume of source rock of anomalous lead deposits is outlined. Calculations for Jersey, Reeves Macdonald and Bluebell mines indicate that the radiogenic lead component of these deposits could have been derived from 1 to 10 cubic kilometers of source rock containing 3 ppm uranium (and approximately 12 ppm Th) if only one-third to one-half of the radiogenic lead in the source were extracted during a period of concentration and mineralization. Kootenay arc deposits can be divided into two classes on the basis of minor element contents of galenas. This division closely corresponds to the following geological types of deposits: 1. replacement deposits with no evidence of open space filling, and 2. deposits with evidence of open space filling and variable amounts of wallrock replacement. Minor element contents of galenas from Salmo-type replacement deposits suggest but do not prove a fairly low temperature of mineral deposition. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Bandelierkop Formation of the Southern Marginal Zone (SMZ) of the Limpopo Belt consists of metamorphosed ultramafic, mafic and sedimentary rocks. Metamorphic conditions indicated by the petrography of these different rock groups are consistent with upper amphibolite to granulite facies. The ultramafic and mafic rocks are geochemically akin to peridotitic-pyroxenitic intrusive rocks and high-Mg basalts respectively. Metamorphism of these two rock groups in the SMZ was an essentially closed system process, except for the highly volatile phases such as H₂O and CO₂. The metasediments appear to represent a sequence of high (Mg+Fe)-greywackes and/or deep-water shales with minor amounts of iron formation material. The unusually mafic character of the metasediments can be ascribed to a high ultramafic + mafic source component to the original sediment. Some modification of the major and trace element compositions of the pelitic rocks has been caused by the removal of partial melts and the metamorphism of the pelitic rocks is not therefore considered to have occurred under closed system conditions. Variable extraction of partial melts is implied by the chemical variations shown by the pelitic rocks and is also suggested by the presence of large pegmatitic felsic bodies which are commonly found close to the pelitic rocks. Detailed petrographic study of the Bandelierkop Formation rocks suggests an increase in metamorphic grade, and/or a decrease in water activity, from south to north within the Southern Marginal Zone. Peak metamorphic conditions of 730°C + 65°C at pressures of 6.1 ± 1.5 kbars may be deduced from a careful application of several cation thermometers and barometers on selected mineral analyses. A rigorous application of garnet-biotite thermometry to the pelitic rocks indicates that the transition from orthoamphibole gneisses in the south to orthopyroxene-bearing rocks in the north of the SMZ terrane, is a function of changing biotite composition and/or decreasing water activities rather than an increase in metamorphic temperatures. In contrast to the major and trace element data, the stable isotope data for the ultramafic and mafic rocks in the SMZ indicate open system behaviour for some of these rocks, but closed system behaviour for the pelites. Extraction of SO to 70% partial melts from the pelitic rocks, should not, however, have affected the δ¹⁸O value of the restite. Petrological and stable isotope data in the SMZ rocks are consistent with retrogression in all these rocks and open system behaviour for oxygen in some ultramafic and mafic rocks, being caused by the crystallization and accompanying fluid release of melts produced during prograde metamorphism of the pelitic rocks. Small scale (-5 to 30m's) heterogeneity is implied by both oxygen and carbon stable isotope compositions of closely spaced rock samples, even for those collected from within large "shear zones", suggesting small fluid/rock ratios for most of the samples in the high-grade terrane or heterogeneous stable isotopic compositions of the fluids. Furthermore, a similarity in mineral-mineral stable isotope fractionation factors is observed for all the pelitic rocks, including the orthoamphibole gneisses found immediately south of the orthopyroxene isograd. These features preclude the presence of pervasive fluid infiltration after peak metamorphism. Two implications are, that granulite facies metamorphism in the SMZ terrane was not caused by an influx of mantle derived CO₂-rich fluid and, that the orthoamphibole gneisses are not retrogressed equivalents of the granulites found to the north of the orthopyroxene isograd. It is suggested that this isograd represents a change in the water activities of the rocks during metamorphism. Apparent disequilibria in mineral - mineral stable isotope fractionations observed amongst different minerals within any one pelitic rock, may be explained by a combination of the crystallization of residual melt within these rocks and oxygen diffusion amongst minerals which have not reached their oxygen-closure. The concordant quartz-plagioclase, quartz-biotite and plagioclase-biotite oxygen isotope equilibration temperatures are taken to represent minimum crystallization temperatures for the melts (-560°C), while successively higher quartz-orthopyroxene, quartz-amphibole and quartz-garnet oxygen isotope equilibration temperatures are a function of increasing closure temperatures for the orthopyroxene, amphibole and garnet respectively. The minimum estimate to peak metamorphic temperatures is given by the quartz-garnet oxygen isotope temperature averaging 736 + 52°C. If oxygen diffusion experiments performed in hydrothermal systems are appropriate for the SMZ rocks, then cooling rates for the SMZ terrane could have been as low as 12 to 25°C/My over a temperature range of 480 to 600°C. Stable isotope modeling of hypothetical fluids that may have been in equilibrium with the high-grade rocks, suggests that a mixture of CO₂ and H₂O, with CO₂/H₂O mole ratios > 0.1 can precipitate both quartz and carbonate of stable isotope composition similar to those determined for quartz and carbonate from the mineralized Archaean lode gold deposits of the Murchison and Pietersburg greenstone belts. A model involving granulite facies metamorphism, partial melt extraction and subsequent release of fluids, Au, K and S upon crystallization of such melts, appears to be viable for gold mineralization occuring in the adjacent lower grade greenstone belts and in the high-grade terrane of the Southern Marginal Zone.

The relative abundances of the stable and long-lived Isotopes of rubidium, cesium, strontium, cerium, neodymium, and samarium resulting from the ther­mal neutron fission of U^235 and Pu^239 were determined mass spectrometrically. Special precautions were taken to eliminate or at least minimize contamination of the sub-microgram quantities of fission products with the naturally occurring elements. By using isotope dilution the yields of isotopes of different elements were related with very good precision. Sufficient information was available to evaluate from such results the absolute cumulative yields of twenty-seven mass chains for U^235 fission. It was possible from the results of the present study of make a quantitative comparison between the yields of the heavy fragments for U^235 and Pu^239 fission, with special attention being given to the fine structure supposedly resulting from the influence of nuclear shells involving 50 and 82 neutrons. / Thesis / Master of Science (MS)

The methods available for the calculation of ratios of partition functions for isotopic molecules were examined critically and compared. A number of calculations were made for carbon as well as for selenium systems using the exact method rather than an approximate one. Improvements were made to the sample handling system of the mass spectrometer to prevent sample cross-contamination and to reduce the time needed for sample changeover. Four sets of experiments were performed. The kinetic isotope effects in the reductions to Se° of Se^V1 and Se^1V were studied as were the isotope exchange reactions between Se° and Se^1V and between Se^1V and Se^V1. Estimates were made of the ratios of rate constants and isotope exchange equilibrium constants for 82Se and 76Se in these systems and these were compared with the theoretical values. / Thesis / Doctor of Philosophy (PhD)

M.Sc Thesis / Northern peatlands are able to persist on the landscape and continue to accumulate carbon in the long-term thanks to a suite of ecohydrological feedbacks that confer resilience to disturbance such as the drier and warmer conditions associated with climate change. One feedback of particular interest operates between peat pore-water residence time and chemistry, whereby changes in hydraulic structure with depth restrict turnover in deeper layers, allowing decay end-products to accumulate and thermodynamically suppress decomposition. In this way, the burial of peat facilitates its continued recalcitrance. While this feedback has been observed in more extensive northern peatlands, at least on the side of carbon dynamics and geochemistry, there has been no observational study of profiles of pore-water residence time nor has it been assessed in smaller peat-forming systems. The peat-filled bedrock depressions of the Canadian Shield offered a unique opportunity to study this feedback in systems where primary peat formation occurs under geological constraints on growth in the form of the largely impermeable bedrock. These systems play important hydrological, biogeochemical and ecological roles on the landscape. Understanding their resilience on the landscape may reveal key insights into their evolution and their response to disturbance, which is increasing in the eastern Georgian Bay region. These systems have previously exhibited a hydrological feedback between water table depth and specific yield that varies with depression size. To assess the hydraulic structure that constrains pore-water transport to support continued recalcitrance, profiles of hydrophysical properties and pore-water residence time in four deep (>0.4 m mean depth) and five intermediate (<0.4 m) depressions. Hydraulic structure varied by depression size and depth in the profile, with very low hydraulic conductivities measured in the catotelms of deep sites. The two classes of depressions exhibited distinct hydrology, in the form of dampened water table fluctuations and hydraulic gradients in the deeper sites. Stable isotope analysis of δ2H and δ18O was used to estimate relative pore-water residence times using the simplified inverse transit time proxy (ITTP) for samples collected from May-August 2017. These estimates were observed to have similar controls to hydraulic structure and a close relationship with depth-averaged conductivity on a whole-site basis. While it was hypothesized that the catotelms of deeper depressions would have less pore-water turnover than that of shallower depressions, the ITTP was only able to differentiate between catotelm-acrotelm and deep-intermediate individually. The relative residence time of pore-water in deep catotelms based on δ2H was longer than in intermediate catotelms, but not significantly. These results broadly supported previous pore-water residence time work despite the likely ubiquitous promotion of turnover in the wetter-than-average study period. Carbon accumulation was quantified from extracted peat cores and pore-water chemistry was assessed as dissolved organic matter (DOM) quality using fluorescence spectrometry of monthly pore-water samples. Fluorescence and absorption indices varied by the same depression characteristics as hydraulic structure of site size and depth, but only the humification index exhibited significant temporal variation. Characterization of pore-water DOM was somewhat unclear across the seven indices calculated, although the DOM of intermediate sites appeared to be less humified, more recently produced and autochthonous in nature compared to deep sites Carbon accumulation was predominantly driven by the waterlogged, relatively stable carbon stored deep in the catotelm. Total carbon accumulated in the profile, and even more so the amount stored in the catotelm, were strongly related to depression depth. The thickness and carbon storage of the acrotelm was insensitive to depression morphology, with some intermediate sites being considered all acrotelm based on their water table behaviour. Overall, deeper peat-filled depressions showed stronger signs of the pore-water residence time-chemistry feedback, suggesting the carbon stored in their deep peat layers is more resilient to decay, by way of less conductive deep peat, longer relative pore-water residence times and more humified, less biologically active DOM. In order to comprehensively assess this feedback, longer stable isotope records are essential to ensure robust residence time estimates through differing moisture conditions, and a greater variety of depression sizes may allow for elucidation of threshold depression sizes where hydrological behaviours diverge. This study, at least on a categorical basis, can be used to inform conservation strategies of the relative vulnerability of these important reptile habitats and carbon stores, as well as guide restoration efforts to construct sufficiently deep, resilient systems. / Thesis / Master of Science (MSc)

The various concepts of the fission process, mass and charge distribution, and fine structure in fission yields are reviewed. Details and results of mass spectrometric analyses of fission-product samples of cesium, rubidium, and strontium are reported. Absolute yield values have been assigned to the mass 87, 135, and 137 chains. Relative yields of the mass 88 and 90 chains have been determined. A mechanism is postulated to account tor anomalies in fission fine structure. The Glendenin mechanism of instantaneous neutron emission is found to require modification. / Thesis / Master of Science (MS)

A study of methods for determining the relative abundances of the chlorine isotopes, and the results of mass spectrometric analyses of several chlorine-containing substances. Small variations are shown to exist in nature between the relative abundances of the chlorine isotopes in halite samples from at least two different localities. Other studies involving chlorine isotopes and their possible fractionation are included. / Thesis / Master of Science (MSc)

Both bromodeprotonation and bromodesulphonation occur during aqueous bromination of sodium p-methoxybenzenesulphonate, A, and potassium l-methylnaphthalene-4-sulphonate, B. Extensive kinetic studies reported here suggest that bromodesulphonation of A proceeds by a two-step process with Br2 as the brominating species, but do not completely exclude Br+ (or H2OBr+) acting in either a one- or two-step process. For B, the kinetic data can be interpreted by either a one- or two-step process with Br2 as the brominating species. Kinetic sulphur isotope effects have been measured for the bromodesulphonation of A and B and found to vary with bromide-ion concentration, thus strongly supporting the two-step process involving molecular bromine. The kinetic results for the bromodeprotonation of A cannot distinguish between a one- and two-step process involving Br2l the two-step mechanism has been confirmed by the observation of a variation in kinetic hydrogen isotope effect with bromide-ion concentration. / Thesis / Doctor of Philosophy (PhD)

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Call number: LD2668 .T4 1978 H75 / Master of Science