Field examination of late-tectonic, U-, Th-, Mo-, and REE-bearing pegmatites, skarns, and veins in the southwestern Grenville Province indicates that they are spatially and temporally related. These observations lead to a renewal of the hypothesis that the deposits were related to intrusion of the pegmatites and formation of the skarns. The granitic pegmatites are related either to chemical fractionation of late-tectonic granitic plutons or mid-crustal anatectic melts with emplacement at the present structural level. This interpretation is based primarily on their discordant nature, late tectonic age, and moderately-evolved chemical composition. At the time of pegmatite emplacement the host rocks remained above 500$\sp\circ$C. Endoskarns (within pegmatite) are dominated by calc-silicate minerals (Ca pyroxene, scapolite, andradite, and titanite) and have a similar origin to the hybridized pegmatites involving metasomatic reaction of the pegmatite and skarn by either diffusion or infiltration of chemical components into the pegmatite. The exoskarns are dominantly primary with a mineralogical zonation which may be characterized as proximal to distal with relation to the pegmatite. The absence of calcite within the proximal skarn is explained in that the pegmatite-derived fluids were undersaturated in calcite resulting in dissolution. Calcite veins represent distal primary skarn. Secondary tremolite-phlogopite-sulphide replacement veins occur within the primary skarn. Fluorite-apatite-calcite veins, have inclusions and selvages of coarse-grained biotite, K-feldspar, Ca amphibole, Ca pyroxene, and titanite with occasional magnetite, sulphides, and rate-element minerals. Common minerals within the pegmatites, skarns, and veins facilitated a chemical comparison of these minerals. The colour of ferromagnesian phases, particularly Ca pyroxene and biotite/phlogopite was used in the field to describe the relative iron contents of these phases. In general, iron was highest in the minerals associated with the pegmatites, and proximal skarn; more magnesium rich in the skarns not directly associated with a pegmatite. Major- and trace-element distribution coefficients (K$\sb{\rm D})$ for coexisting phases in veins and skarns are indistinguishable, although only a few elements (Fe, Mg, Mn, and Zn) have regular distributions. In a more detailed study of the Hunt Mo skarn, four zones have been identified in the exoskarn which is, in part, consistent with observations from many other skarns in the region. The proximal zone 1 assemblage is narrow, coarse-grained (1 metre), and dominantly composed of Fe-rich Ca pyroxene, scapolite (or microcline or albite), titanite, pyrite, and molybdenite (rare quartz). The dominant skarn type, zone 2, is fine- to coarse-grained and consists of Fe-bearing Ca pyroxene, phlogopite/biotite, titanite, pyrite, and pyrrhotite, with irregular phlogopite (possibly secondary) veinlets throughout. Apatite is an accessory phase within zone 2 skarns. The third zone is composed of Ca pyroxene; phlogopite, and tremolite, and occasionally calcite and pyrite which are fine to medium grained. The fourth zone represents small veins hosted in graphite-bearing phlogopite-diopside-dolomite-calcite marble, and is dominated by fine- to medium-grained tremolite, phlogopite, calcite, pyrite $(\pm$ graphite). (Abstract shortened by UMI.)

The Sagan-Afelata area, which extends east approximately 100 km from the Main Ethiopian Rift towards the Adola gold fields, is underlain by high-grade rocks, dominantly biotite and quartzofeldspathic gneiss. The gneissic rocks are characteristically of K-rich mineralogy and appear to form a Proterozoic supracrustal sequence rather than Archean basement as thought earlier. The gneissic rocks were subjected to at least three distinct phases of deformation. The first, D$\sb1$, to which probably several generations of structures are attributed, formed migmatitic layering then isoclinal folds that transposed the layers parallel to flat-lying regional foliation (S$\sb1$), during amphibolite to granulite facies metamorphism. The second, D$\sb2$, formed upright folds in S$\sb1$ and parallel layers with subhorizontal NNW to NNE trending axes, accompanied by amphibolite facies metamorphism that overprinted most rocks. D$\sb3$, resulted in local E-W trending, open, upright folds that are confined to the eastern part of the area. (Abstract shortened by UMI.)

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129I is a fission product with a long half-life (1.57 x 107 yrs) that has important implications as a tool to monitor long-term stability and interactions in the hydrosphere, biosphere and geosphere. In the groundwaters, migration of 129I, which because of its low natural concentrations is assumed to be the same as stable iodine (127I), can be retarded by various reactions with geologic and biologic reservoirs. At Atomic Energy of Canada, Chalk River Laboratories, Ontario, solid, low-level radioactive wastes from industrial, academic and medical applications have been stored in trenches overlying unconsolidated sandy glacial tills and permeable very-fine to fine-grained sands overlying crystalline bedrock. The sandy aquifer system drains into a Swamp comprised of approximately 3 in of sphagnum peat. Hydrologically, most of the yearly precipitation (∼340mm/a) percolates into the underlying aquifer at Area C. This has generated a contaminant plume, having chemical characteristics of a dilute, sanitary landfill leachate, containing 14C (DOC, DIC), tritium (HTO) and levels of 129I which are elevated above present-day precipitation levels of approximately 107 atoms 129I/l water. A comprehensive field and analytical program at this site has been initiated to examine the partitioning of 127I and 129I amongst the various reservoirs in this system and the controlling factors. (Abstract shortened by UMI.)

A digital thematic map of the shallow marine habitats surrounding the Tobago Cays and the Horseshoe Reef was created using a low-cost remote sensing methodology. Colour aerial photographs were selected because of their high spatial resolution and availability. The aerial photographs were scanned, georeferenced, rectified (ground control points and a second order polynomial) and mosaicked to cover the entire study arm. Benthic classes were derived and described objectively using agglomerative hierarchical classification of field data. Supervised classification of the Tobago Cays was obtained using this field derived classification. The final thematic map comprises 8 classes (mixed live coral community, dead coral substratum with mixed algae, seagrass dominated, macro algae dominated, sand dominated, rubble dominated, deep water and beach sands) with an overall accuracy of 87% and a Kappa and Tau coefficients of 85%. Producer and user accuracies of individual classes range between 53% and 100%. (Abstract shortened by UMI.)

This thesis represents the results of a mineral chemical and crystal chemical investigation of trioctahedral and dioctahedral micas from the Paleozoic granitic rocks of the Dunnage, Gander, Avalon and Meguma tectonic zones of the Canadian Appalachians. The objectives of the thesis were: (1) to investigate the relationships between the composition of biotite and the tectonic origin of the host granitic rock. (2) to investigate the significance of quadrupole splitting distributions in the Mossbauer spectra of these Appalachian and other biotite specimens and (3) to investigate the cis and trans-octahedral Fe2+ Mossbauer spectral contributions of dioctahedral (muscovite) micas from the granitic rocks of the Gander zone in New Brunswick. These results of the study am presented as three manuscripts intended for submission to peer-reviewed journals. In the first manuscript, the author document the mineral chemistry of biotite occurring in granitic rocks of the Canadian Appalachians. The most significant variations are changes in total Al contents and Fe/(Fe+Mg) values. Using common oxygen geobarometers, the biotite from the granitic rocks of most zones plot on or above the NNO buffer, indicating moderate oxidizing conditions, whereas biotite from the Meguma zone plots between the QFM and NNO buffers implying fairly reducing conditions during crystallization. The composition of biotite in Appalachian granitic rocks reflects primarily the nature of the host magmas and cannot be readily used for interpreting the tectonic setting of these rocks. In the second manuscript, the methodology of quadrupole splitting distribution (QSD) analysis was used to describe the room temperature 57Fe Mossbauer spectra of 71 specimens of trioctahedral micas from the Paleozoic granitic rocks of the Canadian Appalachians, the granitic rocks of the Hepburn and Bishop intrusive suites of the Early Proterozoic Wopmay orogen, Northwest Territories, and the nepheline syenite of the Cretaceous Mont Saint-Hilaire alkaline intrusion, Quebec. To the author, the details of the crystallochemical controls of the observed QSDs in biotite are not well understood because of a lack of electronic structure calculations that link local distortion environments to quadrupole splitting values. Furthermore, several key crystal chemical parameters of the synthetic phlogopite-biotite-annite solid solution (e.g., Fe/(Fe+Mg), Fe3+/Fe total) do not correlate with any of the QSD features of natural biotites. The most strongly-correlated chemical parameter is found to be Altotal . Finally, in the third manuscript, QSD analysis of specimens of muscovite from granites of the Gander zone in New Brunswick shows that the Mossbauer spectra of these dioctahedral micas fall into two distinct groups. In the first group, two well-resolved octahedral Fe2+ spectral contributions occur whereas, in the second group, a single but broader octahedral Fe 2+ contribution occurs. Furthermore, spectra from the first group clearly show bimodal QSDs for Fe2+. In the second group, the spectra show broad unimodal QSDs for Fe2+. (Abstract shortened by UMI.)

The source of gold in lode gold deposits in metamorphic terrains is debatable. As a test of the "deep source model", the Bamble Shear Belt of southern Norway was studied. A transition from amphibolite to granulite facies takes place over the 30 km width of the Shear Belt. Some 400 samples from various rock units across the Belt were analyzed for a wide range of elements. The results, combined with petrographic studies and data from elemental and isotopic composition of sulfides, are interpreted with emphasis on the processes that have affected the distribution of gold. The oldest exposed rocks in Bamble are a sequence of sedimentary and volcanic materials of early- to mid-Proterozoic age. During the Kongsbergian, or Gothian, orogeny (1600--1450 Ma), all the supracrustal rocks were intruded by a suite of acid-intermediate magmas, and a series of basic dykes and sills known as metabasites. The highest grade portion of Bamble is dominated by tonalitic-trondhjemitic charnockites and subordinate metabasites and metasediments. All rocks in this zone are strongly depleted in LILE, LREE, and HFSE relative to their equivalent rocks from amphibolite and transition zones. Depletion of the elements can be explained by the presence of a CO2-rich fluid during magmatic crystallization, or metamorphic recrystallization. Both metabasites and hyperites are of low-Mg tholefitic nature (MgO < 10%), and bear features typical of destructive margin settings. On MORB-normalized plots, they exhibit marked enrichments in LILE and LREE. The absence of Mg-rich cumulates argues against a functional crystallization model. Both series are the products of low degrees of partial melting. Supracrustal rocks of varied type and origin in Bamble are strongly depleted in Au, As, Sb, and Se relative to the crustal abundance of these elements. The average Au in the Bamble rocks, 0.35 ppb, is only 25% of the crustal abundance of this element. Charnockites are also depleted in Au, As, Sb, and Se. The mean value of Au in these rocks (0.2 ppb) is 20% of the general abundance of this element in felsic rocks elsewhere. Lode gold deposits are commonly associated with alkaline and light REE metasomatism, and a significant enrichment in As, Sb, and Se. Neither special Au-enriched rocks, nor unreasonably large volumes of source rocks are required to produce a giant gold deposit. Shear zones serve as major source areas and principal conduits for extraction and transportation of Au. (Abstract shortened by UMI.)

The Neoarchean Lake of the Woods greenstone belt is located immediately south of Kenora, Ontario within the western part of the Wabigoon Subprovince of the Superior Province. The supracrustal rocks have been subdivided into 3 major lithostratigraphic assemblages. The Lower Keewatin is the oldest assemblage with a zircon U-Pb age of 2738 +/- 2.0 Ma. It consists of Mg and Fe tholeiitic metabasalts. The Upper Keewatin Assemblage disconformably overlies the Lower Keewatin Assemblage. Two geochemically distinct volcanic suites are recognised. The dominant suite consists of compositionally diverse calc-alkaline metabasalt to metarhyolite. Felsic volcanic rocks from this suite yield U-Pb zircon ages ranging from 2712--2723 Ma. A coeval suite of mafic to ultramafic volcanic rocks consists of tholeiitic metabasalt, komatiitic metabasalt and metakomatiite. The Electrum assemblage unconformably overlies the Upper Keewatin Assemblage in the northern part of the belt. It consists of metaconglomerates, metasandstones and minor metavolcanic rocks having detrital ages indicating deposition after 2699 Ma. The volcanic rocks consist of shoshonitic meta-andesite and calc-alkaline metarhyolite. The Electrum shoshonites are part of a chemically diverse suite of potassic igneous rocks emplaced at a late stage in the tectonic evolution of the western Wabigoon Subprovince. The suite is also comprised of silica undersaturated ultrapotassic rocks of the Falcon Island pluton (2695 Ma) and silica saturated monzodiotitic intrusions such as the Don Lake stock. The Falcon Island pluton consists of nepheline-bearing, alkali feldspar syenite and alkali feldspar melasyenite with lessor amounts of clinopyroxenite, monzodiorite, and peraluminous alkali feldspar syenite. A genetic linkage of gold mineralization to oxidized alkaline intrusions has been proposed on the basis of mineral chemical studies from the Abitibi Subprovince. Nd isotopic data from a compositional spectrum of representative rocks from the major stratigraphic units of the belt indicates a major change in the isotopic signature of mantle sources at about 2.7 Ga. Comparison of Nd, Pb and Sr isotope data from a number of well documented potassic suites across the southern Superior Province indicates heterogeneity was widespread in the post 2.7 Ga mantle. The correlation of this isotopic data suggests mixing between a juvenile depleted mantle component and an enriched end-member with isotopic characteristics approaching those of the ancient granitic terrain of Winnipeg River Subprovince and the Opatica and Pontiac metasedimentary subprovinces. (Abstract shortened by UMI.)