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Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a simplified approach to quantify the contribution of individual factors to the historical growth or decline in total travel between two points in time. The method employs person trip rates and distributions of the individual characteristics at the two time points to determine the portion of urban person travel increase or decrease associated with the change in each factor. The paper presents the application of the approach to investigate changes in person travel in the Greater Toronto Area between 1986 and 1996. Specifically, the study determined the change in person travel attributed to each of the following factors independently: change in population size, change in age distribution, change in residential location distribution, and change in employment status distribution (full time, part time, work at home). The data were obtained from the 1986 and 1996 Transportation Tomorrow Surveys (TTSs).Key words: transportation planning, travel demand.Cet article présente une approche simplifiée afin de quantifier la contribution des facteurs individuels à l'augmentation/diminution historique du nombre total de voyages entre deux points dans le temps. La méthode utilise les taux de déplacements des individus et les distributions des caractéristiques individuelles aux deux points dans le temps afin de déterminer l'augmentation/diminution de la portion des déplacements des individus en ville associée au changement de chaque facteur. Ensuite, l'article présente l'application de l'approche afin d'étudier les changements des déplacements des individus dans le Grand Toronto entre 1986 et 1996. Plus particulièrement, l'étude a déterminé que le changement dans les déplacements des individus est attribué à chacun de ces facteurs indépendants, soit le changement dans la taille de la population, le changement dans la distribution de l'âge, le changement dans la distribution des locations résidentielles et le changement dans la distribution du statut d'emploi (temps plein, temps partiel, travail à la maison). Les données ont été obtenues dans le Transportation Tomorrow Surveys (TTS) de 1986 et 1996.Mots clés : planification des transports, demande de déplacements.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Individual tree diameter at breast height (DBH) distribution is an important information for forest management planning. Forest managers obtain the DBH data either by field measurements or estimations using predictive models. However, probability distribution models are still lacking or need improvement. Therefore, we aimed to construct and fit diameter distribution models that reflect forest structure and composition change. We evaluated gamma, log-normal, and Weibull probability distribution functions (PDFs) for two commercially important tree species, black spruce (Picea mariana (Mill) B.S.P.) and jack pine (Pinus banksiana Lamb), grown in natural stands across Ontario, Canada. We modelled the parameters of the distributions as a function of stand-level variables for these species. We used DBH data from 735 permanent sample plots. Our results showed that all three evaluated PDFs reflected observed DBH distribution. We demonstrated that the moment-based recovered parameters could represent the maximum likelihood-estimated parameters precisely, and parameters of the PDFs can be modelled as a function of stand-level dynamic covariates. The models unbiasedly predicted the PDF parameters DBH means and DBH classes. The R2 of the model fit ranged between 0.35 and 0.98 for the predicted parameters and 0.90 and 0.97 for the predicted DBH. [ABSTRACT FROM AUTHOR]

Glyphosate-resistant giant ragweed (Ambrosia trifida L.) was first identified in Canada in 2008. Although early studies attributed resistance in this species solely to non-target site mechanisms, the presence of a proline (P) to serine (S) mutation at position 106 of EPSPS2 in common and giant ragweed has recently been reported. The objective of this research was (i) to determine whether a P106S mutation is present in historical samples of giant ragweed seed collected from the site of the first report of glyphosate resistance, and (ii) to determine the frequency and distribution of P106S in resistant and susceptible biotypes collected as part of historical surveys throughout southwestern Ontario. [ABSTRACT FROM AUTHOR]

Non-industrial wood ash may be an effective forest soil nutrient supplement but its use in Canada is largely restricted because of unknown concentrations of trace metal contaminants. Sugar maple (Acer saccharum Marshall) is particularly sensitive to low soil calcium (Ca) levels, and though maple syrup is of great economic importance in Canada, it is unknown how wood ash could affect sap chemistry. Non-industrial wood ash (NIWA; 6 Mg·ha−1) applied to experimental plots in Muskoka, Ontario was rich in Ca (27%), while metal concentrations were well below provincial regulatory limits. One-year post-application, significant increases were observed in the treated plots in the soil pH and base cations (Ca, K, and Mg) in the surface soil horizons, and metal concentrations in the litter. Sap yield in the control plots was significantly lower in the first-year post-application than in the second year, but no other differences were found. In both tapping years, sap sweetness remained similar and differences in nutrient and metal concentrations between treatments were generally small and inconsistent. Foliar chemistry remained largely unchanged 1 year following application, except for K that was twice as high in the treated plots. Ultimately, NIWA is unlikely to significantly alter sugar maple sap chemistry, indicating that it is a viable nutrient supplement that can enhance soil fertility in sugar bushes with no impact on sap sweetness. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presents a reply to a comment on the study "Analysis and Reinterpretation of Deformation Features in the Rouge River Valley, Scarborough, Ontario," by N. Eyles and A. Mohajer. Structural analysis of deformation features in relation to local ice flow directions; Interpretation of drumilinoid features; Compatibility of the faults with neotectonic-related or glacial tectonic-related processes.

Aboriginal law has developed to require Aboriginal peoples to be "consulted and accommodated" if their rights may be impacted by a government decision, including a government permit or approval of a project of a private proponent. For example, hunting rights often exist throughout a First Nation's treaty or traditional territory (i.e. far beyond the limits of reserves), and the duty to consult and accommodate can be triggered by mining and other resource development. Contrary to the common understanding of some of those unfamiliar with this area of law, this duty applies not only to activities undertaken under federal authorization, but also to those under provincial authorization. The Crown's "duty to consult and accommodate" Aboriginal peoples has become a central theme in the discussion of natural resource development in Canada. In response to various decisions of Canadian courts, the Government of Ontario significantly overhauled its Mining Act in 2009 to provide for some consultation with Aboriginal communities. Those changes came in to effect in the spring of 2013. This paper will describe the constitutional duty to consult as it has been described and elaborated on by courts in Canada and some of the implications it has for resource extraction in Ontario. It will then undertake a case study discussing Ontario's attempt to respond to its duty to consult by amending the Mining Act regime. Finally, the paper will consider the flaws in the Mining Act and the reasons that exploration companies and surveyors working for them should be prudent and pro-active when undertaking intrusive activities in the traditional territories of Aboriginal peoples. [ABSTRACT FROM AUTHOR]

In this paper, recent boundary cases are considered-but especially as related to Ontario. The choice of jurisdiction is a consequence of the original audience for whom the paper was prepared: real estate lawyers in Ontario. While the activity of case law review and discussion may be seen as an ad hoc and fact-specific exercise, most lawyers in practice choose to remain aware of recent cases in order to stay abreast of new trends. Law schools still use the case law method for teaching-as well as to identify current reported cases as harbingers of potential new trends. Likewise, legislators monitor what emerges from our courts-if only to make sure that there is not a need for remedial legislation in order to possibly "correct" policy implications of a decision or a series of decisions which signal a new trend. Despite its jurisdictional limitations and the review of only most recent cases, this paper is both an example and a reminder that the jurisprudence of boundary law and the work of geomatics professionals continues to evolve. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An estimated 2300 people became seriously ill and 7 died from exposure to microbially contaminated drinking water in the town of Walkerton, Ontario, in May of 2000. The severity of this drinking water disaster resulted in the Government of Ontario calling a public inquiry by Mr. Justice Dennis O'Connor to address the cause of the outbreak, the role, if any, of government policies in contributing to this outbreak, and ultimately, the implications of this experience on the safety of drinking water across the province of Ontario. This paper summarizes relevant evidence presented at the inquiry by the expert panel together with Justice O'Connor's findings addressing the circumstances of the outbreak. These findings are reviewed in relation to the published causes of previous waterborne disease outbreaks that have been reported elsewhere in developed countries. The circumstances surrounding the Walkerton tragedy are an important source of knowledge for those concerned with providing safe drinking water to the public. Although some circumstances are obviously specific to this epidemic, others echo common themes in waterborne outbreaks that have occurred before. These common themes suggest the need for attention to broad issues of drinking water safety in addition to the individual specific details that often command attention. Key words: waterborne disease, Escherichia coli O157:H7, Campylobacter jejuni, Cryptosporidium, Giardia, multiple barriers, health risk.Environ 2300 personnes sont devenues gravement malades et sept personnes sont décédées à la suite d'une exposition à de l'eau potable contaminée par voie microbienne dans la ville de Walkerton, en Ontario, en mai 2000. La gravité de ce désastre d'eau potable a fait que le gouvernement de l'Ontario a lancé une enquête publique, menée par M. le juge Dennis O'Connor, visant à déterminer la cause de cette éclosion, la contribution, s'il y a en une, des politiques gouvernementales à cette éclosion et, en bout de ligne, les répercussions de cette expérience sur la salubrité de l'eau potable partout en Ontario. Cet article résume les preuves pertinentes présentées à l'enquête par le panel d'experts et les conclusions du juge O'Connor sur les circonstances de cette éclosion. Ces conclusions sont revues à la lumière des causes publiées touchant les éclosions antérieures de maladies hydriques qui ont été rapportées ailleurs dans les pays développés. Les circonstances entourant la tragédie de Walkerton sont une source importante de connaissances pour les compagnies fournissant de l'eau potable salubre au public. Bien que certaines circonstances sont évidemment spécifiques à cette épidémie, d'autres font penser à des thèmes communs aux éclosions hydriques survenues auparavant. Ces thèmes communs suggèrent le besoin de porter attention aux grandes questions de la sécurité de l'eau potable en plus des détails uniques spécifiques qui doivent souvent être examinés. Mots clés : maladie hydrique, Escherichia coli O157:H7, Campylobacter jejuni, Cryptosporidium, Giardia, barrières multiples, risque pour la santé. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

This paper reports the results of a laboratory study of the effects of (i) manhole proximity to installation site, (ii) pipe slope (i.e., approach velocity), (iii) upstream head measurement location, and (iv) submergence on the "hydraulics" of two types of sewer weirs used by the City of Ottawa. The City's streamlined form of broad-crested weir and its compound-shaped sharp-crested weir were initially calibrated for a "pipe straight"-arrangement (no upstream manhole is present) for a wide range of flow conditions at 0.2%, 0.4%, and 1.0% pipe slopes. The calibration tests were then repeated with the weirs positioned immediately downstream of a model manhole structure ("manhole"-arrangement). Corresponding data sets were compared to determine the effects of (i) approach velocity and (ii) manhole proximity (for two different shapes of manhole "benching") on the respective weir discharge coefficients.Key words: sewer weirs, broad-crested weir, compound sharp-crested weir, calibration, sewer benching, discharge coefficients.Cet article rapporte les résultats d'une étude en laboratoire sur les effets de : (i) la proximité des bouches d'égout du site d'installation, (ii) la pente des conduites (i.e., vélocité d'approche), (iii) l'emplacement des mesures de la hauteur de la colonne d'eau en amont, et (iv) la submersion sur « l'hydraulique » de deux types de crêtes pour égouts utilisés par la ville d'Ottawa. Les profils d'écoulement des crêtes rectangulaires de la ville et de ses crêtes triangulaires on été calibrés au départ pour un arrangement de « conduites droites » (aucune bouche d'égout présente en amont), pour une variété de conditions d'écoulement ayant des pentes de conduites de 0,2%, 0,4% et 1,0%. Les tests de calibration ont été répétés avec les crêtes positionnées immédiatement en aval d'un modèle d'une structure de bouche d'égout (arrangement « bouche d'égout »). Les banques de données correspondantes ont été comparées afin de déterminer les effets de : (i) la vélocité d'approche, et (ii) la proximité de la bouche d'égout (pour deux types différents de formes de bouche d'égout) sur les coefficients d'écoulement des crêtes respectives.Mots clés : crêtes pour égouts, crête rectangulaire, crête triangulaire, calibration, structure de support pour égouts, coefficients de déversement.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Canadian coastal waters of the Pacific Ocean and the Atlantic Ocean as well as inland freshwater habitats in Ontario were sampled for centrohelid heliozoans (free-living heterotrophic single-celled organisms) over a period of nearly five decades. More than 60 species and subspecies were revealed, including 1 Triangulopteris, 1 Raphidocystis, 2 Pseudoraphidocystis, 3 Raineriophrys, 4 Pseudoraphidiophrys, 12 Choanocystis, 15 Pterocystis, and 25 Acanthocystis taxa. Of these, 22 were officially named and described as new to science based primarily on the morphology of the siliceous scales that cover the cell. New species were compared with images and/or descriptions of close "relatives" to validate their new species assignments. New data on five species of Acanthocystis and one species of Choanocystis required revisions of their descriptive taxonomy that in some cases resulted in the splitting off of separate species or subspecies. Very little can be concluded about global distribution of centrohelid heliozoans, owing to the paucity of records. For many of the taxa reported here, previous records consist of just one or two findings from other parts of the world. One example is Choanocystis antarctica Tikhonenkov and Mylnikov, 2011 that was previously known only from Antarctic seawater, but is reported here from an Ontario softwater lake. [ABSTRACT FROM AUTHOR]

Forest fragmentation and introduced pathogens are negatively impacting trees and forests globally, including the Carolinian forest of southern Ontario, Canada. Multiple species at risk live in this threatened but biodiverse forest, including the endangered Cornus florida (eastern flowering dogwood), which is now limited to fragmented woodlots, and has been decimated by the introduced fungal pathogen Discula destructiva (dogwood anthracnose). Ongoing management of C. florida in Canada is challenged by multiple knowledge gaps, two of which we aimed to address in this study. We first evaluated the association between anthracnose disease prevalence and a suite of ecological and environmental variables across 21 sites. Across our sites, larger trees tended to have the highest disease incidence, and trees on shallow slopes had the most crown dieback. We then quantified genetic diversity and gene flow, and found that genetic structure has not been substantially impacted by habitat fragmentation, although dispersal typically covers short distances. However, genetic diversity is relatively low in smaller populations and in younger trees. Localized dispersal and eroding genetic diversity may limit future adaptation and hence exacerbate population declines. We recommend that managers prioritize plantings in small populations, avoid shallow slopes, and track younger trees to evaluate age-related mortality. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Animal Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An unusually rich and extensive 5 m sequence of organic-rich sediments (ca. 13 000 to ca. 4500 BP) from a drained glacial kettle near Brampton, Ontario, has produced a large and varied assemblage of fossil insects. Coleoptera (beetles) from the base include species typical of northern boreal or tree line habitats today. Approximately one metre above the base of the section (ca. 11 500 BP), there is an abrupt appearance of numerous bark beetles (family Scolytidae) and other Coleoptera that inhabit boreal forests. Temperate species whose ranges are predominantly or totally south of the Ontario border, appear, beginning at ca. 9500 BP, suggesting environmental conditions similar to modern ones. Younger Dryas and Pre-Boreal Oscillation cold events may be evident in lower parts of the boreal sequence, although considerations of temporal and climatic resolution make interpretation somewhat ambiguous.Une séquence exceptionnellement féconde et vaste de sédiments riches en matière organique (vers 13 000 à vers 4 500 BP) s'étend sur une hauteur 5 m dans une marmite glaciaire drainée près de Brampton en Ontario; cette séquence a fourni un grand assemblage varié d'insectes fossiles. Les Coléoptères à la base comprennent des espèces typiques des présents habitats boréals du nord ou de la limite des arbres d'aujourd'hui. Environ un mètre au-dessus de la base (vers 11 500 BP) il y a une apparition soudaine de nombreux scolytes (famille des Scolytidae) et d'autres Coléoptères qui habitent les forêts boréales. Les espèces tempérées dont les étendues sont surtout ou entièrement au sud de la frontière de l'Ontario, semblent débuter vers 9 500 BP, suggérant des conditions environnementales semblables aux conditions modernes. Des événements de froid du Dryas récent et de l'oscillation préboréale peuvent être évidents dans les parties inférieures de la séquence boréale, bien que les considérations de résolution temporelle et climatique rendent l'interprétation quelque peu ambiguë.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Presents further discussion of a study concerning the effects of fire suppression in the boreal forest in Ontario. Impact of suppression on fire size; Evidence on the increase in the fire-return interval; Disclosure on the average annual burn fractions for protected and unprotected forests.

Structural information about that portion of the economically important Destor–Porcupine Deformation Zone and its associated faults, which lie buried under many metres of Clay Belt sediments in the region north of Matheson, Ontario, must rely principally on interpretation of geophysical data. In this area, the Archean greenstones of the Abitibi are crosscut by at least three generations of strongly magnetic diabase dykes. The predominant dyke set, the Matachewan, trend north–south, orthogonal to structures in the greenstones. Directional horizontal derivative analysis of the total magnetic field, which has a much sharper angular cutoff than that provided by standard Fourier-based filters, provides a method for separating the magnetic contributions from these two sources. This analysis revealed the existence of a previously unidentified fault (the Winslow fault) located to the north of, and parallel to, the economically significant Pipestone Fault. We also define a second new fault, the Carr fault, that is intimately associated with the existence of a buried felsic intrusive complex in Carr Township. Possible associations between these faults and previously known faults defined from surface mapping programs are explored.On doit se fier surtout à des interprétations de données géophysiques pour obtenir des informations structurales sur la portion d'importance économique de la Zone de déformation Destor–Porcupine et ses failles associées qui se trouvent enfouies sous plusieurs mètres de sédiments du Clay Belt dans la région au nord de Matheson, en Ontario. Dans cette région, les roches vertes archéennes de l'Abitibi sont recoupées par au moins trois générations de dykes de diabase fortement magnétiques. L'ensemble de dykes prédominant, le Matachewan, a une direction N–S orthogonale aux structures dans les roches vertes. L'analyse directionnelle de la dérive horizontale du champ magnétique total, qui a une coupure angulaire beaucoup plus abrupte que celle des filtres standard basés sur les séries de Fourier, fournit une méthode pour séparer les contributions magnétiques de ces deux sources. Cette analyse révèle l'existence d'une faille antérieurement non identifiée (la faille Winslow) située au nord de, et parallèle à, la faille Pipestone, une faille d'une grande importance économique. Nous définissons également une seconde nouvelle faille, la faille Carr, qui est intimement associée à l'existence d'un complexe intrusif felsique enfoui dans le canton de Carr. Nous étudions aussi les associations possibles entre ces failles et d'autres failles connues antérieurement alors que définies par des programmes de cartographie de surface.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Four different seismic methods were used extensively to evaluate the shear wave velocity of soils and rock in the city of Ottawa, Canada, from which the travel-time weighted average shear wave velocity (Vs) from surface to 30 m in depth (Vs30) and the fundamental frequency (F0) were computed. Three main geological or geotechnical units were identified with distinct shear wave velocities: these consist of very loose thick post-glacial fine-grained sands, silts, and clays (Vs <150 m/s, thickness up to 110 m), firm glacial sediments (Vs ~580 m/s, thickness ~3 m), and very firm bedrock (Vs ~1750-3550 m/s). The seismic methods applied were downhole interval Vs measurements at 15 borehole sites, seismic refraction-reflection profile measurements for 686 sites, high-resolution shear wave reflection 'landstreamer' profiling for 25 km in total, and horizontal-to-vertical spectral ratio (HVSR) of ambient seismic noise to evaluate the fundamental frequency for ~400 sites. Most of these methods are able to distinguish the very high shear wave impedance of and depth to bedrock. Sparse earthquake recordings show that the soil amplification is large for weak motion when the soil behaves linearly. Quatre méthodes sismiques différentes ont été grandement utilisées afin d'évaluer la vitesse des ondes de cisaillement des sols et roches dans la ville d'Ottawa, Canada, à partir desquelles la vitesse moyenne des ondes de cisaillement pondérée selon le temps de parcours (Vs) de la surface jusqu'à une profondeur de 30 m (Vs30) et la fréquence fondamentale (F0) ont été calculées. Trois unités géologiques ou géotechniques principales ont été identifiées selon des vitesses des ondes de cisaillement distinctes : des sables, silts et argiles post-glaciaires fins, lâches et épais (Vs <150 m/s, jusqu'à 110 m d'épaisseur), des sédiments glaciaires fermes (Vs ~580 m/s, ~3 m d'épaisseur) et du substratum rocheux très ferme (Vs ~1750-3550 m/s). Les méthodes sismiques appliquées étaient des mesures de Vs par intervalle en fond de forage pour 15 sites de forage, des mesures du profil de réfraction-réflexion sismique pour 686 sites, du profilage de la réflexion des ondes de cisaillement à haute résolution « landstreamer » pour 25 km linéaire au total, et le ratio spectral horizontal-vertical (RSHV) du bruit sismique ambiant pour l'évaluation de la fréquence fondamentale sur environ 400 sites. La majorité de ces méthodes sont capables de distinguer l'impédance très élevée aux ondes de cisaillement et la profondeur jusqu'au substratum rocheux. Quelques mesures de séismes montrent que l'amplification du sol est grande pour des mouvements faibles lorsque le sol de comporte de façon linéaire. [ABSTRACT FROM AUTHOR]

The Neoarchean Pukaskwa batholith consists of pre-, syn-, and post-tectonic phases emplaced over an interval of 50 million years. Pre-tectonic phases are broadly synvolcanic and have a high-Al tonalite-trondhjemite-granodiorite (TTG) affinity interpreted to reflect derivation by partial melting of basaltic crust at lower crustal or upper mantle depths. Minor syn-tectonic phases slightly post-date volcanism and have geochemical characteristics suggesting some involvement or interaction with an ultramafic (mantle) source component. Magmatic emplacement of pre- and syn-tectonic phases occurred in the midcrust at paleopressures of 550-600 MPa and these components of the batholith are thought to be representative of the midcrust underlying greenstone belts during their development. Subsequent to emplacement of the syntectonic phases, and likely at approximately 2680 Ma, the Pukaskwa batholith was uplifted as a structural dome relative to flanking greenstone belts synchronously with ongoing regional sinistral transpressive deformation. The driving force for vertical tectonism is interpreted to be density inversion (Rayleigh-Taylor-type instabilities) involving denser greenstone belts and underlying felsic plutonic crust. The trigger for initiation of this process is interpreted to be an abrupt change in the rheology of the midcrust attributed to introduction of heat from the mantle attendant with slab breakoff or lithospheric delamination following the cessation of subduction. This process also led to partial melting of the intermediate to felsic midcrust generating post-tectonic granitic phases at approximately 2667 Ma. We propose that late density inversion-driven vertical tectonics is an inevitable consequence of horizontal (plate) tectonic processes associated with greenstone belt development within the Superior Province. Le batholite néoarchéen de Pukaskwa comprend des phases pré-, syn- et post-tectoniques mises en place durant une période de 50 Ma. Les phases pré-tectoniques sont largement synvolcaniques et elles ont une affinité Al et TTG (« tonalite-trondhjemite-granodiorite ») élevée qui est interprétée comme étant le reflet de la dérivation par fusion partielle d'une croûte basaltique à des profondeurs de croûte inférieure ou de manteau supérieur. Des phases syntectoniques mineures sont légèrement plus tardives que le volcanisme et elles ont des caractéristiques géochimiques qui suggèrent une certaine implication ou interaction avec une composante de source ultramafique (manteau). La mise en place magmatique des phases pré- et syntectoniques a eu lieu dans le milieu de la croûte à des paléopressions de 550-600 MPa et ces composantes du batholite seraient représentatives des ceintures de roches vertes sous-jacentes, au centre de la croûte durant leur développement. Après la mise en place des phases syntectoniques, et probablement vers 2680 Ma, le batholite de Pukaskwa a été soulevé en dôme structural par rapport aux ceintures de roches vertes de part et d'autre, et ce, de manière synchrone avec la déformation transpressive régionale senestre en cours. La force motrice derrière le tectonisme vertical serait une inversion de densité (instabilités de type Rayleigh-Taylor) impliquant les ceintures de roches vertes plus denses et la croûte felsique plutonique sous-jacente. Le déclencheur pour l'initiation de ce processus est interprété comme étant un changement abrupt dans la rhéologie de la croûte moyenne attribué à l'introduction de chaleur du manteau auxiliaire à la rupture de la dalle ou à la délamination lithosphérique suivant la cessation de la subduction. Ce processus a aussi mené à une fusion partielle de la croûte moyenne intermédiaire à felsique générant des phases granitiques post-tectoniques vers 2667 Ma. Nous proposons que la tectonique verticale poussée par l'inversion de densité tardive soit une conséquence inévitable des processus tectoniques horizontaux (plaques) associés au développement de ceintures vertes dans la Province du Supérieur. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Bones of small vertebrates (mammals, birds, snakes, fish, amphibians) have been recovered from time to time from sites in postglacial sediments at Hamilton, Ontario, for over a century. One of these sites, at Westdale Ravine, was previously assigned a Glacial Lake Iroquois age (ca. 12 000 years BP), but is now considered compatible with environments during or since the Hypsithermal (last 5000 years). A corrected radiocarbon date of 4330 ±210 years BP confirms such an age and indicates that the bones are younger than and intrusive within the Glacial Lake Iroquois sediments in which they were found. Pendant plus d’un siècle, des ossements de petits vertébrés (mammifères, oiseaux, serpents, poissons, amphibiens) ont, de temps à autre, été prélevés de sédiments postglaciaires en différentes localités à Hamilton (Ontario). Une de ces localités, du ravin Westdale, à laquelle un âge correspondant au lac glaciaire Iroquois (environ 12 000 ans avant le présent) a, par le passé, été attribué, serait compatible avec les conditions environnementales présentes durant ou depuis la période hypsithermale (les derniers 5000 ans). Une datation au radiocarbone (âge corrigé de 4330 210 ans avant le présent) confirme un tel âge et indique que les ossements sont plus jeunes que les sédiments du lac glaciaire Iroquois dans lesquels ils se trouvent, et qu’ils y sont donc intrusifs. [ABSTRACT FROM AUTHOR]

Copyright of Botany is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Environmental Engineering & Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Zoology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The 20-year successional development of understory vegetation was investigated in jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana (Mill.) BSP) plantations in northern Ontario, in relation to stand species composition, species diversity, and the rate of change in stands of different post-disturbance ages. Detrended correspondence analysis (DCA) ordination of plantation stands using species composition data from 1978 and 1998 indicated variation among stands in directions and rates of change in species composition over time. Rank correlations of environmental variables with the DCA axes suggested a light–moisture gradient along the first axis, driven by soil texture and overstory species, and a gradient representing time since disturbance and stand development along the second axis. Although overall beta diversity among stands remained constant over time, some convergence was found among a smaller group of stands, and divergence was noted between spruce and pine stands. Species composition also became more highly correlated with environmental variables through time. From 1978 to 1998, species richness increased in young, dry pine stands; decreased in older, dry pine stands; and decreased in young spruce stands. The understory vegetation in stands on mesic sites was more diverse than that on dry, sandy sites at both times. The rate of change in understory species composition slowed with time after disturbance, indicating an increasing stability in micro en vi ron men tal conditions as the influence of harvesting disturbance became weaker with time.Le développement sur une période de 20 ans de la succession de la végétation de sous-étage a été étudié dans des plantations de pin gris (Pinusbanksiana Lamb.) et d'épinette noire (Piceamariana (Mill.) BSP) situées dans le Nord de l'Ontario en lien avec la composition en espèces du peuplement, la diversité des espèces et le taux de changement dans des peuplements d'âge différent issus de perturbations. L'ordination des plantations par l'analyse de correspondance en utilisant les données de composition en espèces de 1978 et de 1998 indiquait une variation entre les peuplements dans la direction et le taux de changement dans la composition en espèces en fonction du temps. Les corrélations de rang des variables environnementales avec les axes associés à l'analyse de correspondance suggèrent l'ex istence d'un gradient de lumière et d'humidité le long du premier axe, déterminé par les espèces de l'étage dominant et la texture du sol, ainsi qu'un gradient représentant le développement du peuplement et le temps écoulé depuis la perturbation le long du deuxième axe. Bien que dans l'ensemble la diversité bêta parmi les peuplements soit demeurée constante dans le temps, une certaine convergence a été observée parmi un plus petit groupe de peuplements et une divergence a été notée entre les peuplements d'épinette et de pin. Avec le temps, la composition en espèce est également devenue plus étroitement corrélée avec les variables environnementales. De 1978 à 1998, la richesse en espèces a augmenté dans les jeunes peuplements secs de pin et a diminué dans les plus vieux peuplements secs de pin et les jeunes peuplements d'épinette. La végétation de sous-étage dans les peuplements sur des stations mésiques était plus diversifiée que sur les stations sèches et sableuses aux deux moments. Le taux de changement dans la composition en espèces de sous-étage a diminué avec le temps après la perturbation, reflétant la stabilité croissante des conditions en vironnementales à mesure que l'influence de la perturbation due à la récolte s'atténuait.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Describes the spatial and temporal patterns associated with canopy interception, throughfall and net forest water along a black spruce topo-sequence situated in northwestern Ontario. Detection of downward shifts in the potential of hydrogen ions for throughfall; Demographic profile of the study area; Modal conditions for three discrete vegetative communities.

Evaluates the soil properties responsible for the external corrosion of cast iron mains in Toronto, Ontario. Description of the city's water distribution network; Processes associated with corrosion; Classification of soil samples.

Presents a study that estimated the urban metabolism of the Greater Toronto Area (GTA) in Ontario. Background on the use of urban metabolism analyses in quantifying the overall fluxes of energy, water and wastes into an urban region; Analysis of inputs to the GTA urban ecosystem; Results and implications.

Comparison of litho-, bio-, and chemostratigraphy in two cores from the northeastern margin of the Michigan Basin (Manitoulin Island) and from within the Ottawa Embayment (eastern Ontario) identifies interbasinal differences of Late Ordovician platform foundering linked to Taconic orogenesis. Graptolite biostratigraphy defines an east-to-west younging (late Edenian to early Maysvillian) of platform burial. A regional unconformity likely caps the platform succession. In both basins, an increased supply of mafic material appears during the final stages of platform collapse, with the accumulation of organic-rich (<8%), petroliferous shales (Collingwood Member -- Michigan Basin; Eastview Member -- Ottawa Embayment). Both units preserve evidence for deposition coincident with increased dysoxic to possible anoxic bottom-water conditions, but the Collingwood Member accumulated under a relatively stable paleoceanographic environment. Rhythmic interbedding with platform limestone in eastern Ontario, combined with evidence for fluctuating paleoproductivity, suggests the depositional environment of the Eastview Member was more sensitive to higher order controls affiliated with tectonic, oceanographic, and (or) sea level variation. Such interbasinal differences likely reflect a greater rate of subsidence in the Manitoulin region transforming platform sedimentation to a distal ramp facies. In eastern Ontario, a lesser rate of subsidence maintained a shallower water, but open margin, setting. Burial of the Upper Ordovician platform, as preserved in eastern Ontario, occurred during peak dysoxic conditions, with deposition of a hemipelagic facies (Billings Formation) that marks the peak supply of clay-size mafic-derived sediment. Bottom-water ventilation occurred only with appearance of abundant Taconic-derived distal turbidites. An equivalent hemipelagic facies appears to be absent from the Manitoulin region. However, equivalent resedimented deposits are represented by the Blue M [ABSTRACT FROM AUTHOR]

Presents a study that investigated the application of numerical models in determining exchange flows between Lake Ontario and Hamilton Harbour in Ontario. Concerns over the pollution level of Hamilton Harbour; Comparison among several models for assessing the effects of inflows from Lake Ontario; Results and implications for cleanup operations and sewage diversions.

Focuses on changes in phytoplankton abundance, biodiversity and community structure in three small Precambrian Shield boreal forest lakes in northwestern Ontario for several years before and after experimental watershed and shoreline clearcut logging operations and associated forest regeneration practices. Possible effects of forest harvesting within drainage basins; Data analysis; Total phytoplankton biovolumes in the three lakes.

Two newly discovered kimberlites from the Wawa area, Ontario, are Group-1 kimberlites in their petrographic, mineralogical, geochemical, and isotopic features. They contain mantle minerals and xenoliths of the Fe–Ti-association (magnesian ilmenite, iron-rich olivine, orange Ti-pyrope garnet, augite, and ferroan enstatite) and of the Cr-association (chromian spinel, forsteritic olivine, purple Cr-pyrope garnets, chromian diopside, and enstatite); minerals of Fe–Ti-association are much more abundant. Minerals of eclogitic association are absent. Both G-10 pyrope garnets and high Cr spinels typically associated with diamond are represented in the Cr-association. The average age of the kimberlites is 1097 ± 7 Ma; i.e., contemporaneous with other alkaline igneous rocks in the Wawa area. Equilibration pressures and temperatures of mantle xenoliths plot close to a 40–45 mW m[sup –2] geotherm. On the basis of the Ni-in-garnet geothermometer, garnets from the Wawa kimberlites equilibrated at 800–1350°C, and at least in part within the diamond stability field. It is likely that kimberlitic magma was derived from light rare earth-element-enriched asthenospheric mantle.Deux kimberlites découvertes récemment dans la région de Wawa, en Ontario, sont des kimberlites de Groupe 1 selon leurs caractéristiques pétrographiques, minéralogiques, géochimiques et isotopiques. Elles contiennent des minéraux du manteau et des xénolites d'association Fe–Ti (ilménite magnésienne, olivine riche en fer, grenat pyrope-Ti orange, augite et bronzite) et d'association Cr (diopside chromifère, olivine à fostérite, grenats pyrope-Cr pourprés, diopside chromifère et enstatite); les minéraux de l'association Fe–Ti sont beaucoup plus abondants. Il y a absence de minéraux d'association éclogite. Les grenats pyropes G-10 et les spinelles à haute teneur en Cr, typiquement associés au diamant, sont représentés dans l'association Cr. L'âge moyen des kimberlites et de 1097±7Ma, c.-à-d. elles sont contemporaines des autres roches ignées alcalines de la région de Wawa. Les pressions et les températures d'équilibre des xénolites du manteau se positionnent près du géotherme 40-45 mWm[sup –2] . En se basant sur le géothermomètre « Ni dans le grenat », les grenats provenant des kimberlites de Wawa auraient trouvé leur équilibre entre 800 et 1350 ºC et au moins en partie dans le champ de stabilité du diamant. Il est probable que le magma kimberlitique provenait du manteau asthénosphérique enrichi en éléments de terres rares légers.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The Oak Ridges Moraine aquifer feeds the headwaters of major rivers in the Greater Toronto Area and is an important source of domestic water supply. Recognizing the rapid rate of urban growth in the region, there is a concern that changing land use along the moraine must be strictly controlled if groundwater is to be adequately protected. To date, efforts to incorporate groundwater protection into the land use planning process have been hampered by an inadequate quantitative hydrogeological understanding of the aquifer system. Focusing on the Duffins Creek watershed, comprehensive hydrogeological studies including a numerical flow model now provide a quantitative insight into the hydrogeologic function of the moraine. These studies demonstrate that 60% of the entire basin groundwater discharge to streams occurs along the south flank of the moraine, and 60% of this headwater discharge occurs below the 275 m above sea level contour, one of the commonly accepted planning boundaries of the moraine. The remaining discharge is contributed by aquifers within and underlying deposits that extend to the south of the moraine. While 75–80% of the watershed discharge to streams is received from the uppermost aquifer, 20–25% is contributed by deeper aquifers underlying the extensive Northern–Newmarket till aquitard. This work shows that the moraine sediments represent just one component of a regional flow system that extends beyond the morphological boundary of the moraine. This has important implications for groundwater protection, as it demonstrates the need for management strategies that incorporate the regional groundwater flow system and not the moraine in isolation.L'aquifère de la moraine de Oak Ridges alimente le cours supérieur de grandes rivières dans la région du Grand Toronto et constitue une importante source d'alimentation en eau domestique. Conscient du taux rapide de croissance urbaine dans la région, on croit que le changement d'utilisation des terres le long de la moraine doit être rigoureusement contrôlé afin de protéger adéquatement l'eau souterraine. À ce jour, les efforts pour inclure la protection de l'eau souterraine dans le processus de planification d'utilisation des terres ont été retardés par une connaissance quantitative hydrogéologique inadéquate du système d'aquifères. Ciblant le bassin hydrographique de Duffins Creek, des études hydrogéologiques complètes, incluant un modèle numérique de l'écoulement, fournissent maintenant un aperçu quantitatif de la fonction hydrogéologique de la moraine. Il démontre que 60 % de tout le débit souterrain du bassin a lieu le long du flanc sud de la moraine. Soixante pour cent de ce débit a lieu sous le niveau amsl de 275 m, soit l'une des limites couramment utilisées comme limite de planification pour la moraine de Oak Ridges. Le débit restant est contrôlé par des aquifères à l'intérieur et sous des dépôts qui se prolongent au sud de la moraine. Alors que 75 à 80 % du débit du bassin hydrographique vers les ruisseaux provient de l'aquifère supérieur, 20 à 25 % provient d'aquifères plus profonds sous la grande couche de till semi-perméable capacitive de Northern–Newmarket. Cette étude montre que les sédiments de la moraine ne représentent qu'une composante d'un système régional d'écoulement qui s'étend au-delà de la limite morphologique de la moraine. Cela représente des implications importantes pour la protection de l'eau souterraine car cela démontre le besoin d'avoir des stratégies de gestion qui incorporent le système régional d'écoulement de l'eau souterraine et non seulement la moraine.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Geometry and timing of deformation affecting Ordovician bedrock and overlying Pleistocene sediments in the Rouge River valley near Scarborough, Ontario, are analysed to evaluate whether or not the structures are a result of glacial action or neotectonic activity. Extensive data on local and regional ice-flow directions are used to evaluate the kinematic compatibility between the observed faults and folds and the local ice-flow directions. Jointing and multiple episodes of faulting affect both the Ordovician bedrock and the overlying Pleistocene sediments. At one site, the bedrock is displaced by a normal fault by a minimum of 1.2 m. Crosscutting relationships constrain the majority of the faulting in the Rouge River valley as being coeval with deposition of the lower Bowmanville till during the Nissouri phase (ca. 23–15 ka), and possibly younger at one locality. The youngest regional ice-flow direction is northwestward; however, local ice-flow directions are highly variable. This can be explained by local perturbation enhanced by the presence of drumlinoid features in the area. Most deformation features are compatible with local and regional ice-flow directions. Glaciotectonic ice-push and ice-thrust deformation affected the Thorncliffe Formation after about 23 ka. Although some faults appear to be kinematically incompatible with ice-flow directions, six boreholes drilled to 52 m depth revealed only minor vertical offsets of bedrock strata in the uppermost 20 m, and an absence of obvious fault offsets deeper, precluding the possibility that the faults observed in the surface exposures were caused by deep-seated neotectonic stresses.Nous avons analysé la géométrie et le moment de la déformation touchant le socle ordovicien et les sédiments sus-jacents du Pléistocène dans la vallée de la rivière Rouge près de Scarborough, en Ontario, afin de déterminer si les structures résultent d'une action glaciaire ou d'une activité néotectonique. De nombreuses données sur les directions locales et régionales de l'écoulement glaciaire ont servi pour évaluer la compatibilité cinématique entre les failles et les plis observés et les directions locales des écoulements glaciaires. Le réseau de diaclases et les nombreux épisodes de failles affectent à la fois le socle ordovicien et les sédiments sus-jacents du Pléistocène. À un site, le socle est déplacé d'au moins 1,2 mètres par une faille normale. Des relations d'entrecroisements restreignent la plupart des failles de la vallée de la rivière Rouge à être contemporaines de la déposition du till Bowmanville inférieur au cours de la phase Nissouri (vers 23–15 ka) et possiblement plus jeunes à une localité. La direction de l'écoulement régional le plus jeune est vers le nord-ouest; toutefois, les directions locales de l'écoulement glaciaire sont hautement variables. Cela peut être expliqué par une perturbation locale rehaussée par la présence de formes drumlinoïdes dans la région. La plupart des paramètres de déformation sont compatibles avec les directions locales et régionales de l'écoulement glaciaire. La déformation glaciotectonique et de chevauchement glaciaire a affecté la Formation de Thorncliffe un peu après 23 ka. Bien que quelques failles semblent être incompatibles d'un point de vue cinétique avec les directions d'écoulement, six forages à une profondeur de 52 mètres ont révélé seulement de mineurs déplacements verticaux des strates du socle dans les 20 mètres supérieurs et une absence de déplacement évident de failles à de plus grandes profondeurs, écartant ainsi la possibilité que les failles observées dans les affleurements de surface aient été causées par des contraintes néotectoniques à de grandes profondeurs.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Estimates critical loads of acidity and the amount by which these critical loads are exceeded by atmospheric deposition, for 1469 lakes from five regions in south-central Ontario, using single lake chemistry measurements and sulphur deposition data for the period 1976-1999. Reduction in the portion of lakes with critical load exceedances due to the declining sulphur deposition.

A basal sequence of flood basalt lavas associated with the Neoproterozoic Midcontinent rift system crops out in Alona Bay along the southeastern shore of Lake Superior in Ontario. The Alona Bay lava succession is about 1200 m thick and lies just north of the well-studied, contemporaneous Mamainse Point Formation. Detailed chemostratigraphy of the Alona Bay lavas suggests they are grossly correlative with the basal portion of the Mamainse Point Formation. For instance, like the basal part of Mamainse Point Formation, the Alona Bay section contains numerous high-MgO lavas and can be subdivided into 4–5 groups with distinct chemical characteristics. Chemical variations within the Alona Bay groups are largely the result of fractional crystallization, likely at moderate pressures. One small group of Alona Bay lavas also carries the compositional imprint of crustal contamination. The remaining inter-group chemical distinctions at Alona Bay are the consequence of temporal changes in partial melting and source character. With time and development of the Midcontinent rift, degrees of melting increased; mean pressures of melting decreased, reducing garnet control; and lithospheric source contributions waned. Similar temporal variations during flood basalt evolution have been documented elsewhere.Une séquence basale de laves de basaltes des plateaux associée au système de rift mi-continental (Néoprotérozoïque) affleure dans la baie d'Alona, le long de la rive sud-est du lac Supérieur en Ontario. La succession de laves de la baie d'Alona a une épaisseur d'environ 1200 m et elle se trouve juste au nord de la Formation de Mamainse Point qui lui est contemporaine et qui a été bien étudiée. Une chimiostratigraphie détaillée des laves de la baie Alona suggère une vague corrélation à la section basale de la Formation de Mamainse Point. Par exemple, tout comme la partie basale de la Formation de Mamainse Point, la section de la baie d'Alona contient de nombreuses laves à haute teneur de MgO et elle peut être divisée en 4–5 groupes ayant des caractéristiques chimiques distinctes. Les variations chimiques à l'intérieur des groupes de la baie d'Alona découlent en grande partie d'une cristallisation fractionnée, probablement à des pressions modérées. Quelques laves de la baie d'Alona présentent aussi une surimposition compositionnelle montrant une contamination de la croûte. À la baie d'Alona, les distinctions chimiques qui subsistent entre les groupes résultent de changements temporels dans la fusion partielle et le caractère de la source. Avec le temps, et le développement du rift mi-continental, les taux de fusion ont augmenté; les pressions moyennes de fusion ont diminué, réduisant le contrôle du grenat; les contributions de la source lithosphérique ont aussi diminué. D'autres documents rapportent de semblables variations temporelles au cours de l'évolution du basalte de plateau.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]