Exothermic Reactions. The high temperatures sought in the experiments were produced by heat released from exothermic reactions. Two such reactions were used, that of thermite and that of silicon-ferric oxide. Thermite is a mixture of aluminum and iron oxide. Ferric oxide was used in the experiments because its reaction with aluminum releases more heat per gram of reactants than do those of ferrous oxide or magnetite. For complete reaction, the mixture should contain 54 parts of aluminum and 159.7 parts of ferric oxide by weight.

Processes of oxidation and secondary enrichment of sulphide minerals have challenged the minds of geologists, chemists and geochemists for over a century. In spite of extensive and varied investigations in the field and laboratory, the chemical mechanisms involved remain poorly understood. During the past decade, mainly through the pioneering work of Garrels (1960) and co-workers, the concept of thermodynamic mineral equilibria has been applied to reactions occurring in aqueous solutions at surface or near surface conditions. Mineral relationships in the zones of oxidation and supergene enrichment have been graphically portrayed by Garrels (1954) in Eh-pH diagrams by means of thermodynamic calculations following the methods of Pourbaix (1949).

This thesis is a study of phase equilibria among iron-rich silicate minerals in the metamorphic iron formations in the Cape Smith Belt, New Quebec, and is based on the chemical analyses of eight iron-rich silicate minerals. Mineral assemblages investigated include: grunerite-stilpnomelane, grunerite-stilpnomelane-almandite-biotite, stilpnomelane-minnesotaite-iron chlorite, all with quartz, magnetite, and calcite. Their stability relationships in the system FeO-MgO-Fe203-Al203-Si02-H20, during metamorphism are discussed.

The thesis area is located along the south shore of Grassy Portage Bay and along the west shore of Redgut Bay of Rainy Lake, in the townships of Watten and Halkirk in the Fort Francis Mining Division of Western Ontario. It is underlain by a series of metamorphised basic intrusives, volcanic rocks, sedimentary rocks and two granitic intrusive of early (?) Precambrian age. All intrusives are apparently younger than the stratified rocks; the granites are probably the youngest rocks in the area. The meta-basic intrusives consist of a main mass of hornblende gabbro and lesser amounts of associated rocks which are thought to be differentiates of the gabbro magma.

This thesis contains the results of an investigation into the stratigraphy and paleontology of the early Middle Ordovician Chazy group in the St. Lawrence Lowland. As such, it forms part of a series of studies of the Ordovician formations in this region, carried out by graduate geology students at McGill University. It follows the work of Harris (1933) and Okulitch (1934) on the Black River group, and that of Byrne (1958) on the Beekmantown group. Despite the excellent accessibility of the best exposures in the vicinity of Montreal, the Chazy group here, as a unit by itself, has not previously been studied in detail.

Chemical weathering of rocks including anorthosite is studied experimentally. Photographic expression of anorthosite is then outlined and statistical studies of slopes and grain size of products of weathering are made. Then tone of aerial photographs and color photography are considered. It is concluded that anorthosite should weather faster in areas where vegetation is present, and that the geomorphic expression of anorthosite is mainly related to jointing; in other aspects of surface expression, anorthosite is not different from other rock types.

A Precambrian layered gabbroic intrusion about 560 km^2 in area, of the Skaergaard type, crops out on the middle north coast of Labrador. Border zones and a Layered series are recognized, and have the following characteristics and approximate mean thicknesses. The intrusion displays extreme fractionation resulting in larvikite consisting of mesoperthite, fayalite, ferroaugite, and ore as the uppermost differentiate. Mineral variation and differentiation are described by means of quantitative mineralogy.

The composition and structural features of feldspars from the rocks of Mounts Royal, Bruno, Johnson, St. Hilaire, Rougemont, Yamaska, Shefford and Brome have been studied by optical and x-ray diffraction methods. Extensive diffraction work did not disclose the presence of highly disordered feldspars (high comparative forms). However, the plagioclases of these rocks belong to a distinct series whose order-disorder relations are in agreement with the geological setting of the intrusives and would classify the rocks as hypabyssal rocks (shallow seated rocks). The alkali feldspars of the Monteregian rocks belong to the low-albite--orthoclase series. The presence of this series of alkali feldspars and the absence of feldspars of the low-albite--microcline series is a characteristic of these rocks that is regarded to be a consequence of their cooling history. The rate of cooling of the igneous masses and the annealing of the rocks under predominantly dry conditions are thought to have been the principal factors responsible for the incomplete ordering of the feldspars. The trends of crystallization and the interrelations between the rock types are discussed on the basis of the compositional data obtained on the feldspars. A qualitative diagram for pressures of approximately 1000 bars has been presented to explain the paragenesis of the feldspar associations encountered in the Monteregian Rocks.

Some copper sulphide minerals recrystallized when heated in a temperature gradient in an argon-sulphur atmosphere, and acicular and lenticular crystals grew down gradient. The crystal composition was determined by the composition of the starting material, temperature, and the sulphur vapour pressure. The purpose of these experiments was to determine: (i) what effect the texture of the surface over which the copper sulphide migrated had upon the diffusing mineral, (ii) what relationship existed between temperature and the weight of the mineral transferred under a constant temperature gradient, (iii) what were the critical factors causing the migration, and, (iv) whether chalcopyrite (CuFeS2) and bornite (Cu5FeS4) would migrate to the same degree under similar conditions.

The Oka anorthosite, lying thirty miles northwest of Montreal, was mapped with particular attention to the distribution of the anorthosite varieties present and the geological structure of these occurrences. It was found that the anorthosite varieties were irregularly distributed within the area, even within an individual outcrop. All the anorthosite was classified according to Buddington’s classification of anorthosites. Samples were collected upon which detailed petrographic studies were made. These studies included flat stage and universal stage work on the plagioclase, determination of the anorthite content of the plagioclase by means of immersion oils, and identification of the accessory minerals. Modal analyses were made on a number of thin sections to insure accuracy of naming.