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Geology topics

Research about Canada

Source-linked reports with geographic coverage including Canada.

297 records · Page 17Linked to original sources
USGS1966

Sediment transport in a Precambrian ice age: The Huronian Gowganda Formation

The Gowganda Formation of Ontario consists of conglomerates, quartzites, and argillites deposited in a glacial environment. The distribution of varved argillites and silty limestones suggests continental and marine facies, respectively. Pebble and ripple-drift orientations, distribution of limestones, striated pavements, distribution of the underlying Bruce Group, and Huronian quartzite paleocurrents support the conclusion that sediment transport was from north to south.

Ontario↗
USGS1959

Chemical composition of argillites of the cobalt series (precambrian) and the problem of soda-rich sediments

Two new chemical analyses show that the varved argillites of the Precambrian Cobalt series of Ontario, Canada, contain more Na 2 O than K 2 O and have a Na 2 O/K 2 O ratio higher than most pelitic rocks but similar to that found in many graywackes. Published chemical data substantiate these observations. The Cobalt materials are also low in CaO but otherwise have a composition compatible with their presumed glacial origin. Albitization of the detrital plagioclase feldspar seems to best account for the low lime and high soda content of these rocks. X-ray data confirm the presence of albite. Spectrographic analyses of the argillites are also given.

Ontario↗
USGS1955

The Sudbury [Ontario] aeromagnetic map as a test of interpretation methods

The method of interpretation of aeromagnetic maps described by Vacquier, Steenland, Henderson, and Zietz (1951) is applied to several anomalies on the aeromagnetic map of part of Sudbury, Ontario. The resulting average computed depths deviate from the known depths by less than 10 percent. The aeromagnetic map is described and compared with the known surface geology.

Ontario↗
USGS1944

The fluorspar deposits of Saint Lawrence, Newfoundland

Fluorspar from Newfoundland, eighth ranking producer of the world, comes entirely from the St. Lawrence district. Here pre-Cambrian lavas and pyroclastics, Cambrian sedimentary rocks, Ordovician (?) volcanic and sedimentary rocks, and a Paleozoic alaskite-granite comprise the bedrock.Epithermal fluorite veins occupy steeply dipping fault fissures in granite, rhyolite porphyry, and lamprophyre. Eleven veins show walls bearing nearly horizontal striations; one vein bears only vertical striations; and the walls of three veins show both horizontal and vertical striations. The strikes of nearly all veins are within 45 degrees of the normal to the walls of the elongated granite mass. Some veins are more than a mile long and contain numerous workable lenses. Veins are of two types: high-grade containing over 95 per cent CaF 2 and averaging about 5 feet thick, and lower grade containing about 75 per cent CaF 2 and averaging between 15 and 20 feet thick.Sulphides, present in small quantities, include pyrite, chalcopyrite, sphalerite, and argentiferous galena. Non-metallic gangue minerals are quartz, calcite, and rarely barite. "Blastonite," a local name for material composed of microcrystalline quartz and brecciated fluorite, in some places forms as much as 10 per cent of a vein. A nodular type of fluorspar probably formed by alternate rotation of fragments of breccia and deposition of fluorite.Regional zoning is shown by the distribution of barite and green fluorite. Barite shows a distinct zone of localization, and green fluorite predominates in veins both near the granite margins and farther from the granite body.This district will undoubtedly occupy a still more prominent position among producers of fluorspar.

Newfoundland↗
USGSDate not supplied

Exsolved magmatic fluid and its role in the formation of comb-layered quartz at the Cretaceous Logtung W-Mo deposit, Yukon Territory, Canada

Comb-layered quartz is a type of unidirectional solidification texture found at the roofs of shallow silicic intrusions that are often associated spatially with Mo and W mineralisation. The texture consists of multiple layers of euhedral, prismatic quartz crystals (Type I) that have grown on subplanar aplite substrates. The layers are separated by porphyritic aplite containing equant phenocrysts of quartz (Type II), which resemble quartz typical of volcanic rocks and porphyry intrusions. At Logtung, Type I quartz within comb layers is zoned with respect to a number of trace elements, including Al and K. Concentrations of these elements as well as Mn, Ti, Ge, Rb and H are anomalous and much higher than found in Type II quartz from Logtung or in igneous quartz reported elsewhere. The two populations appear to have formed under different conditions. The Type II quartz phenocrysts almost certainly grew from a high-silica melt between 600 and 800°C (as β-quartz); in contrast, the morphology of Type I quartz is consistent with precipitation from a hydrothermal solution, possibly as α-quartz grown below 600°C. The bulk compositions of comb-layered rocks, as well as the aplite interlayers, are consistent with the hypothesis that these textures did not precipitate solely from a crystallising silicate melt. Instead, Type I quartz may have grown from pockets of exsolved magmatic fluid located between the magma and its crystallised border. The Type II quartz represents pre-existing phenocrysts in the underlying magma; this magma was quenched to aplite during fracturing/degassing events. Renewed and repeated formation and disruption of the pockets of exsolved aqueous fluid accounts for the rhythmic banding of the rocks.

Yukon Territory↗
USGSDate not supplied

Characterizing the two-dimensional thermal conductivity distribution in a sand and gravel aquifer

Both hydrologic and thermal transport properties play a significant role in the movement of heat through permeable sedimentary material; however, the thermal conductivity is rarely characterized in detailed spatial resolution. As part of a study of the movement of thermal plumes through a sand and gravel aquifer, we have constructed a two-dimensional profile of thermal conductivity. This work consisted of: (i) measuring the thermal conductivity of the soil solids, λ s , for the main stratigraphic units using the steady-state divided-bar apparatus and estimating conductivity from mineral composition; (ii) measuring the volumetric water content and porosity using crosshole ground-penetrating radar; (iii) evaluating four models used to predict the apparent thermal conductivity, λ, of variably saturated soils and selecting the best model using the information-theoretic approach, (iv) calculating the λ field on a 0.25-m square cell grid using measured data and the selected model, and (v) simulating thermal transport within the two-dimensional domain using a finite element numerical model. The apparent thermal conductivity in the saturated aquifer ranges from 2.14 to 2.69 W m −1 K −1 with a mean of 2.42 W m −1 K −1 Numerical simulations show that the heterogeneous thermal conductivity field results in increased thermal dispersion that is most pronounced at the plume front. Our values for λ and λ s may be used for glacial soils with similar mineralogy and texture. Our methods may also be used at other sites to construct the thermal conductivity distribution.

Ontario↗