Scanning electron microscopy and mercury intrusion porosimetry are used in parallel to identify the structure of a medium sensitivity Champlain clay. The clay structure is observed firstly on intac...

Study of the structure of a sensitive Champlain clay and of its evolution during consolidation

Diffuse reflectance spectra of 15 mineral species commonly associated with sulphide-bearing mine wastes show diagnostic absorption bands related to electronic processes involving ferric and/or ferrous iron, and to vibrational processes involving water and hydroxyl. Many of these absorption bands are relatively broad and overlapping; however, spectral analysis methods, including continuum removal and derivative analysis, permit most of the minerals to be distinguished. Key spectral differences between the minerals are illustrated in a series of plots showing major absorption band centres and other spectral feature positions. Because secondary iron minerals are sensitive indicators of pH, Eh, relative humidity, and other environmental conditions, spectral mapping of mineral distributions promises to have important application to mine waste remediation studies.

Spectral reflectance properties (0.4–2.5 μm) of secondary Fe-oxide, Fe-hydroxide, and Fe-sulphate-hydrate minerals associated with sulphide-bearing mine wastes

This paper describes the use of quantitative mineralogy and specific surface area in interpreting the index properties of clayey soils from nine sites in Eastern Canada. Samples representative of t...

Mineralogy, chemistry, and physical properties interrelationships of some sensitive clays from Eastern Canada

Mechanism and effect of chemical weathering of sedimentary rocks

Following the partial collapse of a shale embankment in Derbysllire, a detailed mineralogical, chemical and electron microscopical investigation was carried out to establish whether the crushed mudstone fill had been significantly affected by chemical weathering after emplacement. Samples of unweathered and weathered Namurian mudrocks from the area were also analysed for comparison and laboratory experiments carried out to simulate abiotic and biochemical shale weathering. It is concluded that chemical alteration of the shale is a rapid process and that significant post-emplacement chemical and mineralogical changes occurred in the embankment fill. The main reactions involve oxidation of framboidal pyrite, leaching of carbonates by sulphuric acid, formation of authigenic sulphate and iron hydroxide minerals, and leaching of cations from clay minerals. In parts of the fill forming the outer shoulders of the embankment, up to 10lume loss may have occurred due to acid leaching.

Chemical and biochemical weathering of pyritic mudrocks in a shale embankment

Oxidation of pyrite and crystallization of sulphate minerals in rock fractures have locally produced ground heaving in excess of 10 cm in the foundations of a college at Sainte-Foy, near Quebec (Quebec). Black shales of the Sainte-Foy Formation are involved; they contain about 2% disseminated framboidal pyrite and 3% calcite. Reaction products identified with a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray chemical analyser (EDXA) are iron hydroxides and numerous sulphate minerals containing calcium, iron, potassium, aluminum, magnesium, manganese, barium, and strontium. In Ontario, heaving of black shales has been observed in the Ottawa area in particular; rock expansion there was mainly attributed to crystallization of gypsum along the bedding plane cleavages of the shales. At Sainte-Foy, fibroferrite, a fibrous iron–aluminum sulphate mineral, probably also contributed significantly to heaving.

Black shale heaving at Sainte-Foy, Quebec, Canada

The mineralogy of sensitive clays in relation to some engineering geology problems — An overview

Pop-ups, which form in response to high horizontal surface and near-surface stresses, were recognized on the floors of two quarries in metropolitan Quebec City. This note constitutes the first publ...

The occurrence of pop-ups in the Québec City area

La methodologie d'inventaire des granulats du Quebec a ete elaboree a partir des methodes mises au point en Norvege et en Ontario (Canada). Ces regions ont des conditions geologiques semblables a celles du Quebec. L'inventaire des granulats est effectue en considerant les depots de granulats comme des gisements zones selon certains criteres de qualite: quantite qualite des granulats et exploitabilite. Il est difficile de classer selon un seul critere d'utilisation, ainsi les classes derivees du systeme d'evaluation sont limitees a trois. Les reserves sont evaluees en tenant compte des secteurs deja exploites, des zones urbaines et protegees. Les donnees de bases utilisees sont celles provenant des travaux de cartographie du Quaternaire, de la roche en place et des ressources en eau souterraine. Les travaux de terrain sont limites a la visiste de certaines gravieres afin d'echantillonner les facies typiques. Les bases de donnees sur les caracteristiques des granulats des autres agences gouvernementales sont aussi incorporees dans la base de donnees de l'inventaire des granulats d'une region. Cette base de donnees est informatisee a l'aide d'un programme developpe avec le progiciel dBaseIII+pour IBM PC. La methodologie d'inventaire a ete verifiee sur le terrain a partir de deux regions precises: Val d'Or et Quebec sur des feuillets au 1∶50 000.

Jean-Yves Chagnon

Papers

Black shale heaving at Sainte-Foy, Quebec, Canada

The mineralogy of sensitive clays in relation to some engineering geology problems — An overview

The occurrence of pop-ups in the Québec City area

L'inventaire des granulats au Québec