1,843 results
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2. The impact of composite sampling and other data aggregation procedures on pollution detection in the pulp and paper industry
- Author
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Nemetz, Peter N. and Drechsler, Herbert D.
- Subjects
PAPER industry ,POLLUTION - Published
- 1978
3. Volume, dry weight, and kraft pulping of fertilized balsam fir from Nova Scotia
- Author
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Hunt, K., Warren, W. G., and Timmer, V. R.
- Subjects
PAPER industry ,FERTILIZERS - Published
- 1980
- Full Text
- View/download PDF
4. Management of toxic substances and hazardous wastes.
- Author
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Niemela VE
- Subjects
- Biodegradation, Environmental, Canada, Chemical Phenomena, Chemistry, Hot Temperature, Polychlorinated Biphenyls analysis, Refuse Disposal, Waste Disposal, Fluid, Industrial Waste
- Abstract
This paper describes the extent of the hazardous and toxic chemical waste problems in Canada and discusses the management, treatment, and disposal methods commonly used in North America and Europe. The treatment and disposal techniques covered are biological, physical-chemical, incineration technologies, and secure land disposal. Some of the available and emerging technologies for destruction of polychlorinated biphenyls are also described.
- Published
- 1984
- Full Text
- View/download PDF
5. Factors affecting Canadian pulp and paper prices
- Author
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Nautiyal, J. C. and Singh, B. K.
- Subjects
PAPER industry ,FOREST products - Published
- 1984
6. Selected papers from the thermal physiology symposium. Calgary, Alta., Canada, July 21-25, 1986. A satellite symposium of the XXX International Congress of the International Union of Physiological Sciences. Dedicated to the memory of Edward Alexander Sellers. September 14, 1916-August 28, 1985.
- Subjects
- Animals, Canada, History, 20th Century, Humans, Body Temperature Regulation
- Published
- 1987
7. Papers dedicated to the memory of Professor Klaus Rothfels (1919-1987) in recognition of his contributions to cytogenetics.
- Subjects
- Animals, Canada, History, 20th Century, Humans, Cytogenetics history
- Published
- 1989
8. Productivity performance of the Canadian pulp and paper industry
- Author
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Oum, Tae H., Frank, David L., Ghebremichael, Asghedom, and Tretheway, Michael W. Michael W. Tretheway
- Subjects
FOREST products industry ,PAPER industry - Published
- 1990
9. Productivity in the pulp and paper industries of the United States and Canada: a nonparametric analysis
- Author
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Buongiorno, Joseph and Hseu, Jiing-Shyang
- Subjects
MATHEMATICAL analysis ,PAPER industry - Published
- 1994
10. Microbiology and biodegradation of resin acids in pulp mill effluents: a minireview.
- Author
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Liss SN, Bicho PA, and Saddler JN
- Subjects
- Biodegradation, Environmental, Canada, Carboxylic Acids metabolism, Water Pollutants, Chemical toxicity, Diterpenes metabolism, Industrial Waste, Paper, Water Microbiology, Water Pollutants, Chemical metabolism
- Abstract
Resin acids, a group of diterpenoid carboxylic acids present mainly in softwood species, are present in many pulp mill effluents and toxic to fish in recipient waters. They are considered to be readily biodegradable. However, their removal across biological treatment systems has been shown to vary. Recent studies indicate that natural resin acids and transformation products may accumulate in sediments and pose acute and chronic toxicity to fish. Several resin acid biotransformation compounds have also been shown to bioaccumulate and to be more resistant to biodegradation than the original material. Until recently, the microbiology of resin-acid degradation has received only scant attention. Although wood-inhabiting fungi have been shown to decrease the level of resin present in wood, there is no conclusive evidence that fungi can completely degrade these compounds. In contrast, a number of bacterial isolates have recently been described which are able to utilize dehydroabietic or isopimaric acids as their sole carbon source. There appears to be an unusually high degree of substrate specificity with respect of the utilization of abietane congeners and the presence of substituents. Pimaranes do not appear to be attacked to the same extent as the abietanes. This paper reviews the occurrence, chemistry, toxicity, and biodegradation of resin acids in relation to the biological treatment of pulp and paper mill effluents.
- Published
- 1997
- Full Text
- View/download PDF
11. The occurrence of two types of entomopathogenic bacilli in natural populations of the spruce budworm, Choristoneura fumiferana
- Author
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Royama, T., van Frankenhuyzen, K., Eveleigh, E. S., and Strongman, D. B.
- Subjects
SPRUCE budworm ,POPULATION dynamics ,PLANT diseases ,ENTOMOLOGY ,BACTERIA - Abstract
This paper reports the occurrence of two types of pathogenic bacilliin cadavers of spruce budworm, Choristoneura fumiferana, larvae and pupae on balsam fir, Abies balsamea (L.) Mill., foliage sampled in several locations in New Brunswick, Canada. One type forms spores and protein crystals at sporulation typical of Bacillus thuringiensis (B.t.), while the other forms spores but no crystals. The noncrystal-producing bacillus is likely Bacillus cereus rather than an acrystalliferous variety of B.t.. The bacilli infect budworm during most of its life cycle, from hibernating second-instar larvae to pupae, with varying rates of infection, but are never a major cause of mortality. The bacilli also infect other lepidopterous species occurring on balsam fir foliage. Circumstantial evidence indicates that both bacilli occur naturally on the foliage, despite the history of aerial application of B.t.-based insecticides near, if not directly over, our study plots. A subtle impact of these bacilli on the dynamics of spruce budworm populations is discussed. [ABSTRACT FROM AUTHOR]
- Published
- 1997
12. Impact a court terme d'une coupe avec protection de la regeneration sur la gelinotte huppee (Bonasa umbellus) en foret boreale (in French)
- Author
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Ferron, Jean, Courtois, Rehaume, and Dussault, Christian
- Subjects
ANIMALS ,FOREST management ,FRENCH people ,TAIGAS ,TIMBER - Abstract
We studied the short-term impact of cutting with the protection of regeneration (CPR) on ruffed grouse (Bonasa umbellus) and its habitat.Drumming males were surveyed in the boreal forest of western Quebec between 1990 and 1994 in 5 control stands and 10 stands that were cutin 1992. Cutting caused a 50% decline in total density and basal area of trees. In harvested stands, shrubs were less abundant than in control stands. Lateral cover between 1 and 2 m and canopy closure werealso lower in cut stands. In the harvested stands, the density varied between 14.1 and 22.6 drummers/km
2 between 1990 and 1992before the CPR. In 1993, density declined to 10.1 but was reestablished at 21.5 in 1994. Densities did not differ significantly before orafter the CPR nor between cut and uncut stands (p > 0.05). After theCPR, the grouse generally established their drumming sites in the periphery of cut areas. There they found lateral cover and canopy closure similar to those measured in control stands by choosing sites where deciduous shrubs were more abundant than in the remainder of the stand. However, the characteristics of the tree stratum were not optimal; their overall density, that of Betulaceae, and that of Salicaceae were higher near drumming sites located in control stands than those in harvested stands. In harvested stands, drumming sites had a lower total basal area of trees, and namely that of deciduous trees, than in control sites. To maintain ruffed grouse populations immediately after cutting in mixed and deciduous stands of public lands, we suggestthat CPRs be in 15-ha blocks while maintaining a basal area of at least 7.5 m2 /ha, half of which should be in trembling aspen (Populus tremuloides Michx.) and paper birch (Betula papyrifera Marsh.). [ABSTRACT FROM AUTHOR]- Published
- 1998
13. Impact of timber-fee increases on British Columbia forest products companies: an economic and policy analysis
- Author
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Binkley, Clark S. and Zhang, Daowei
- Subjects
ECONOMICS ,FOREST management ,TIMBER - Abstract
On 14 April 1994, the British Columbia government announced a new stumpage formula that, at then-expected product prices, increased the average charge by about $12/m
3 and more than doubled the rate at which stumpage fees change when lumber prices change. Most of the increased revenues are reinvested in the forest sector by a new organization, Forest Renewal British Columbia (FRBC), created specifically for that purpose. Using standard event-study methodologies, this paper documents the net effect of the fee increases and new policy direction on British Columbia forest products companies. After controlling for firm-specific risk and the decline in the Toronto Stock Exchange that occurred at about the same time, the new stumpage policy extracted about $1.0 billion from shareholders of the firms studied, andperhaps $2.4 billion from all licencees (an amount roughly equal to the capitalized after-tax cost of the higher fees). The impact on individual firms is highly correlated with the allowable annual cut (AAC) in replaceable licenses each holds, with an average impact of about$33.3/m3 of AAC. The market appears to have discounted both the good news about offsets in impending timber-supply reductions that the creation of FRBC implies and the reductions in earnings riskthat the new stumpage system provides. When added to the increased regulatory costs associated with the new provincial Forest Practice Code, the timber-fee increases appear to have fully depleted the value of holding British Columbia timber quotas. [ABSTRACT FROM AUTHOR]- Published
- 1998
- Full Text
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14. Cultural, geographical, and sectoral refinements to measures of forest industry dependence
- Author
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Korber, D., Beckley, T., White, W., and Luckert, M.
- Subjects
TIMBER ,FORESTS & forestry ,ECONOMICS ,FOREST products industry - Abstract
Economic base analysis is a limited but useful tool for measuring forest dependence. It cannot measure the full range of forest values (e.g., subsistence, amenity, bequest, and existence values). However, economic base analysis utilizes widely available census data to provide accurate measures of communities dependent on industrial forest activity. This analysis includes Indian reserves and rural census subdivisions previously excluded in studies of economic base dependence. Economic base dependence measures are further improved by including a transfer payment sector. This paper presents findings of forest industry dependence measures using 1991 census data. Results show that including Indian reserves and other rural census subdivisions in the analysis increases the number of forest industry dependent places and population in the Prairie Provinces. The addition of the transfer payment sector to the economic base provides a more comprehensive account of the sources that contribute to the economic diversity of rural locations. These geographical and sectoral refinements to economic base calculations result in a more accurate accounting of forest industry dependence. [ABSTRACT FROM AUTHOR]
- Published
- 1998
- Full Text
- View/download PDF
15. A comparison of several methods for estimating light under a paper birch mixedwood stand
- Author
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Letchford, T., Gendron, F., and Comeau, P. G.
- Subjects
PHOTOSYNTHESIS ,PAPER birch ,FORESTS & forestry ,FOREST management - Abstract
In 1996 we initiated a study to evaluate several techniques for measuring light under broadleaf canopies. Hourly average photosynthetic photon flux density and percent transmittance were measured 1 m above the ground at four points in each of three canopy densities created by a spacing experiment in a 35-year-old paper birch (Betula papyrifera Marsh.) dominated stand located near Prince George, B.C. At each point, fisheye photographs were taken and LAI-2000 plant canopy analyzer (LAI-2000), spherical densiometer, and competition index (Lorimer'sindex) measurements were made. Percent transmittance measurements onan overcast day (1-h average), transmittance measured over periods of 3 h or longer on a clear day, LAI-2000 diffuse noninterceptance measurements, and gap light index determined from fisheye photographs were strongly correlated with growing season percent transmittance (r
2 >= 0.96) as was competition index (r2 = 0.928). Concave spherical densiometer measurements and midday percent transmittance measurements on clear days were also well correlated with measured percent transmittance (r2 >= 0.89). Estimates of understory light by the LITE model were strongly correlated with growing season percent transmittance. Correlations improved with increasing length of the period simulated (r2 = 0.755 for a point measurement on a clear day; r2 = 0.936 for an entire sunny day;and, r2 = 0.953 for the entire growing season). However, this version of the model underestimated percent transmittance in these spaced birch stands by 34-90%. [ABSTRACT FROM AUTHOR]- Published
- 1998
16. Measurementand modeling of spatially explicit variation in light transmission through interior cedar--hemlock forests of British Columbia
- Author
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Canham, Charles D., Coates, K. Dave, Bartemucci, Paula, and Quaglia, Stefan
- Subjects
MEASUREMENT ,FOREST management ,BOTANY ,MODELING (Sculpture) ,CEDAR - Abstract
We have characterized canopy geometry and light transmission by the nine dominant conifer and broad-leaved tree species of the interior cedar-hemlock (ICH) forests of northern British Columbia. Our field data were used to parameterize a spatially explicit model of light transmission through mixed-species forests. That model, a component of the forest dynamics simulator SORTIE, was developed for eastern deciduous forests, and this paper presents a test of that model in a very different ecosystem. Our results show that individual crowns of the ICHforests intercepted much more light than species of eastern deciduous forests but that the canopy as a whole allowed greater light penetration, largely because of openings between the relatively narrow, conical crowns of the western conifers. Light transmission by individualcrowns was correlated with shade tolerance among the conifers (as ineastern deciduous species), but crown depth was not (in contrast with eastern species). Despite the fundamental differences in the natureof light transmission in the two ecosystems, the SORTIE light model developed for eastern deciduous forests was effective at predicting spatial variation in understory light levels in these western coniferous forests. The goodness of fit of such a simple model suggests that the most important factors regulating spatial variation in understorylight levels in these forests are simply the sizes and distribution of nearby trees, and the local sky brightness distribution. Discrete canopy gaps represent a special case in which a region of the canopy is not occupied by crowns. [ABSTRACT FROM AUTHOR]
- Published
- 1999
- Full Text
- View/download PDF
17. The changing landscape of Canada's western boreal forest: the current dynamics of permafrost
- Author
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Halsey, Linda A., Zoltai, Stephen C., and Vitt, Dale H.
- Subjects
PEATLANDS ,TAIGAS ,FROZEN ground ,FOREST management ,DYNAMICS ,CLIMATE change ,BOTANY - Abstract
This paper examines the impact that climatic change over the last millennium has had on aggradation and degradation of permafrost peatlands and the associated change in organic matter accumulation. Permafrost reached its southernmost Holocene extent in boreal continental western Canada during the Little Ice Age with 28 800 km
2 of permafrost peatland present within a sensitive zone demarcated by permafrost degradation. Subsequent degradation of permafrost has occurredin response to warming, with forested bogs changing to nonforested poor fens, associated with rising water levels. In conjunction with this ecosystem change, long-term net organic matter accumulation increases. As permafrost is in disequilibrium with climate, much of the permafrost that remains is in a relict state. Mapping of past and present permafrost distribution from peatland landforms indicates only 9% has degraded since the Little Ice Age, resulting in a 5% increase in long-term net organic matter accumulation. Of the permafrost that remains, 22% is in disequilibrium, located largely in the northern part of the sensitive zone. Additional loss of forested lands will occur inthe future in boreal continental western Canada under present-day climatic conditions as permafrost approaches equilibrium, with a further 11% increase in long-term net organic matter accumulation predicted. [ABSTRACT FROM AUTHOR]- Published
- 2000
18. Influence of millipedes on litter decomposition, N mineralization, and microbial communities in a coastal forest in British Columbia, Canada
- Author
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Prescott, C. E., Chanway, C. P., Holl, F. B., Carcamo, H. A., and Abe, T. A.
- Subjects
MICROBIOLOGY ,NITROGEN ,BIODEGRADATION - Abstract
Laboratory experiments were conducted with the millipede Harpaphe haydeniana haydeniana Wood (Polydesmida: Xystodesmidae) to determine (i) its litter feeding preferences, (ii) rates of leaf litter consumption, (iii) feeding effects on available nitrogen, and (iv) functional microbial diversity. The millipede exhibited a preference for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and, to a lesser extent, Sitka spruce (Picea sitchensis (Bong.) Carriere) litter compared withwestern hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata Donn ex D. Don) litter when given a choice. When only one litter type was provided, millipedes consumed considerably more western redcedar than Douglas-fir, Sitka spruce, or western hemlock. Among the six broadleaf species tested, paper birch (Betula papyrifera Marsh.), bigleaf maple (Acer macrophyllum Pursh), vine maple (Acer circinatum Pursh), and red alder (Alnus rubra Bong.) were consumed at much higher rates than swordfern (Polystichum munitum (Kaulf.) Presl.) or salal (Gaultheria shallon Pursh). Daily rates of conifer litter consumption ranged between 10 and 20% of the millipede's fresh biomass and may translate to 36% of the annual litter fall. Our results suggest that transformation of conifer litter into millipede frass can increase rates of litter decomposition and N mineralization, as well as influence microbial activity and diversity in coastal forests. [ABSTRACT FROM AUTHOR]
- Published
- 2000
19. Output scale, technical change, and productivity in the Canadian pulp and paper industry.
- Author
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Hailu, Atakelty and Veeman, Terrence S.
- Subjects
INDUSTRIAL productivity ,PAPER industry - Abstract
Analyzes the productivity and efficiency in the Canadian pulp and paper industry using input distance function and index number methods. Managerial and policy implications of productivity growth; Components of productivity growth; Contribution of output scale effects, capital disequilibrium to the industry.
- Published
- 2000
- Full Text
- View/download PDF
20. An economic assessment of using the allowable cut effect for enhanced forest management policies: an Alberta case study.
- Author
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Hegan, R. L. and Luckert, M. K.
- Subjects
POPULUS tremuloides ,WHITE spruce ,FOREST management ,SILVICULTURAL systems ,FORESTS & forestry - Abstract
Reports that forest policymakers in Canada are considering the allowable cut effect (ACE) as a potential mechanism to provide tenure holders with incentives to practice enhanced forest management. To investigate the incentives created by the ACE, this paper estimates returns to ACE investments for a trembling aspen (Populus tremuloides Michx.) - white spruce (Picea glauca (Moench) Voss) mixedwood forest in Alberta. A timber supply model is used to optimize harvesting schedules to maximize net present values over a 200-year planning horizon. A number of scenarios are investigated with variations in intensity of silvicultural investments, beginning age-class distributions, levels of flexibility around the allowable annual cut (AAC), calculations of AACs based on coniferous and mixedwood volumes, and green-up constraints. In our simulations, it was difficult to find positive returns to the ACE. Positive returns only occurred when operating under harvesting constraints with a mature starting forest and AAC calculations that ignored deciduous volumes. In those limited cases where there were positive returns to the ACE, returns were higher for extensive, rather than intensive investments. Combining these results with other potential impediments to the ACE, previously identified in the literature, the probability of tenure holders having incentives to undertake ACE investments is low.
- Published
- 2000
- Full Text
- View/download PDF
21. Decomposition of broadleaf and needle litter in forests of British Columbia: influences of litter type, forest type, and litter mixtures .
- Author
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Prescott, C.E., Zabek, L.M., Staley, C.L., and Kabzems, R.
- Subjects
FORESTS & forestry ,WHITE spruce ,DOUGLAS fir ,RED alder ,PAPER birch - Abstract
Reports on the measured rates of decomposition at three sites representing the major mixedwood forest types of British Columbia: (i) boreal forests of white spruce (Picea glauca (Moench) Voss) and trembling aspen (Populus tremuloides Michx.), (ii) coastal forests of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red alder (Alnus rubra Bong.), and (iii) a wet interior forest of Douglas-fir, paper birch (Betula papyrifera Marsh.), and lodgepole pine (Pinus contorta Doug. ex Loud.). Mass loss of litter of each species (both pure and in combination with the other species) that was measured in forests of each species to determine (i) if broadleaf litter decomposed faster than needle litter, (ii) if litter decomposed faster in broadleaf or mixedwood forests than in coniferous forests, and (iii) if mixing with broadleaf hastened decomposition of needle litter; Broadleaf litters that decomposed faster than needles during the first year but, thereafter, decomposed more slowly; Litter that tended to decompose faster in the broadleaf forests than in the coniferous forests; No evidence to indicate that the addition of broadleaf litter hastened decomposition of needle litter; Results that indicate that the mixing of needle litter with broadleaf litter is unlikely to hasten decomposition in mixedwood forests of British Columbia.
- Published
- 2000
- Full Text
- View/download PDF
22. Hinge modifications and musculature of strophomenoid brachiopods: examples across the Ordovician-Silurian boundary, Anticosti Island, Quebec.
- Author
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Dewing, Keith
- Subjects
ORDOVICIAN paleoecology ,ORDOVICIAN stratigraphic geology ,PALEOZOIC paleoecology ,ISLANDS - Abstract
Six modifications to the hinge occur in strophomenoid brachiopods from Anticosti Island: (1) overhanging socket ridges; (2) posterolateral socket ridges along the interarea articulate with grooves on the posterior of teeth; (3) anteromedian dental notches articulate with the crests of socket ridges; (4) dental crenulations on the surfaces of teeth mesh with socket ridges; (5) denticles extend laterally to the cardinal extremities; and (6) the margin of the ventral interarea fits into a long socket along the dorsal interarea forming a lateral tooth. Denticulate hinges and dental notches that typify Silurian and Devonian strophomenids begin in the fauna of the Ellis Bay Formation. Thus the most important interval of strophomenid faunal turnover was at the base of the Gamachian (the base of the Hirnantian) and not at the Ordovician–Silurian boundary. Muscle attachment pads in the delthyrial cavity do not correspond to the positions of either the adductor or diductor muscle scars. Pedicle adjustor muscles in modern brachiopods occupy this position. The round gap between the median fold of the pseudodeltidium and groove on chilidium is proposed as the point of emergence of the pedicle muscle. The tiny foramen, commonly sealed early in growth, is suggested to be part of a neanic water-intake system, active before the growth of the cardinal process in ephebic shells. Once the cardinal process appeared, the foramen was blocked. Recurring types of strophomenid ornamentation, such as posteriorly steepened rugae and checkerboard ornamentation, may have served as a plow to redistribute sediment as the shell was pulled backwards along the pedicle.Six modifications de la charnière sont présentes dans les Brachiopodes strophoménoïdés de l'Île d'Anticosti: (1) la présence de crêtes fossulaires surplombantes, (2) les crêtes fossulaires postéro-latérales le long de l'interaréa sont articulées avec des rainures sur la partie postérieure des dents, (3) des échancrures antéro-médianes s'articulent avec les crêtes fossulaires, (4) des crénulations sur la surface des dents s'engrènent avec les crêtes fossulaires, (5) des denticules sont présentes latéralement jusqu'aux extrémités cardinales et (6) la marge de l'interaréa ventral s'insère dans une longue fossette le long de l'interaréa dorsal, formant une dent latérale. Les charnières denticulées et les échancrures dentales typiques des strophoménidés du Silurien et du Dévonien débutent dans la faune de la Formation d'Ellis Bay. Ainsi, le changement faunique le plus important des strophoménidés se situe à la base du Gamachien (base de l'Hirnantien) et non pas à la limite Ordovicien–Silurien. Les cicatrices des muscles dans la cavité delthyriale ne correspondent pas aux positions des muscles adducteurs ou diducteurs. Les muscles ajusteurs pédonculaires occupent cet endroit dans les Brachiopodes modernes. Le trou rond entre le pli médian du pseudodeltidium et le sillon sur le chillidium est proposé comme point d'émergence du muscle pédonculaire. Le petit foramen, généralement calfaté pendant la croissance précoce, est suggéré comme faisant partie du système néanique d'inspiration d'eau, fonctionnel avant la croissance du processus cardinal dans les coquilles éphébiques. Une fois le processus cardinal apparu, le foramen était bouché. Certains types périodiques d'ornementation de strophoménidés, tels les rugae postérieurement plus abruptes et l'ornementation en damier, auraient pu servir de charrue pour redistribuer les sédiments quand la coquille était tirée vers l'arrière le long du pédoncule.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
23. Reefs during the multiple crises towards the Ordovician-Silurian boundary: Anticosti Island, eastern Canada, and worldwide.
- Author
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Copper, Paul
- Subjects
REEFS ,LANDFORMS ,ORDOVICIAN paleoecology ,ORDOVICIAN stratigraphic geology - Abstract
Multiple latest Ordovician (Rawtheyan–Hirnantian) glaciations in central Africa, with concomitant global sea-level lowstands and cooler, restricted, equatorial carbonate shelves and ramps, interrupted by warmer interstadial highstands, had a dramatic global impact on the tropical shallow-water reef ecosystem and carbonate production. With the Ordovician-Silurian boundary strata on Anticosti Island as a global standard for a carbonate shelf-ramp setting, the latest Ordovician and earliest Silurian reveal three reef phases, ended by three extinctions. The first extinction, towards the end of the Rawtheyan, affected the last "Richmondian"-type reefs (Vaureal Formation, Mill Bay Member). The second extinction was less pronounced, ending with reefs at the base of the Prinsta Member (Ellis Bay Formation), interpreted as the top of the Normalograptusextraordinarius graptolite Subzone. The third and most severe extinction phase capped the Laframboise patch reef complex (Ellis Bay Formation), at the top of the Normalograptuspersculptus Zone. In the paleotropics, the Hirnantian interglacials showed higher biodiversity than either the preceding Rawtheyan or following Rhuddanian (early Llandovery) warm intervals, a feature perhaps achieved by high innovation rates via introduction of "Silurian" reef biotas during the Hirnantian. The Anticosti reef succession is compared with latest Ordovician reefs from northwestern Europe (Baltic Basin and U.K.), the northwestern margins of Gondwana (Spain and Austria), the Urals, Siberia, Kazakhstan, northeast Russia, and China. Reefs show a global decline from the late Caradoc through late Ashgill, marked by hiatuses towards the O–S boundary. A protracted 3–4 million-year recovery phase for Early Silurian tropical marine biotas, generally without reefs, marked the succeeding Rhuddanian; full reef recovery was delayed until the mid-Aeronian.Les dernières glaciations multiples à l'Ordovicien (Rawtheyen–Hirnantien) en Afrique centrale, en même temps que des bas niveaux globaux de la mer, des rampes et des plates-formes carbonatées plus froides et restreintes à l'équateur, interrompues par des hauts niveaux interstadiaires plus tempérés, ont eu un impact global dramatique sur l'écosystème des récifs tropicaux de faible profondeur et sur la production de carbonate. En prenant les strates de l'île d'Anticosti à la limite Ordovicien-Silurien comme une norme globale pour un milieu de rampe-plate-forme, l'Ordovicien terminal et le début du Silurien révèlent trois phases de récifs qui se sont terminées par trois extinctions. La première extinction, vers la fin du Rawtheyen, a affecté les derniers récifs de type « Richmond » (Formation Vaureal, membre de Mill Bay). La deuxième extinction était moins prononcée et s'est terminée avec des récifs à la base du membre Prinsta (Formation d'Ellis Bay), lesquels sont interprétés comme le sommet de la sous-zone du graptolite Normalograptus extraordinarius. La troisième et la plus sévère des phases d'extinction a coiffé le complexe de l'ensemble récifal Laframboise (Formation d'Ellis Bay), au sommet de la zone Normalograptus persculptus. À la hauteur des paléotropiques, les interglaciaires Hirnantien montraient une plus grande biodiversité que les intervalles tempérés du Rawtheyen qui le précédait ou du Rhuddien (Llandovérien précoce) qui le suivait, une caractéristique qui a pu être atteinte par des taux d'innovation élevés par l'introduction de biotes récifaux « siluriens » au cours de l'Hirnantien. La succession récifale Anticosti est comparée aux derniers récifs ordoviciens du nord-ouest de l'Europe (bassin baltique, Royaume-Uni), aux marges nord-ouest du Gondwana (Espagne, Autriche), de l'Oural, de la Sibérie, du Kazakhstan, du nord-est de la Russie et de la Chine. Les récifs montrent un déclin global à partir du Caradocien tardif et durant l'Ashgillien tardif lequel est marqué par des hiatus vers la limite O–S. Une phase prolongée de 3–4 Ma pour les biotes marins tropicaux du Silurien précoce, généralement sans récif, a marqué le Rhuddien qui a suivi : le rétablissement complet des récifs a été retardé jusqu'à l'Aeronien moyen.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
24. Modes of extinction in two Devonian ostracode faunas of western Canada.
- Author
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Braun, Willi K
- Subjects
DEVONIAN paleoecology ,DEVONIAN stratigraphic geology ,PALEOZOIC paleoecology ,ANIMALS - Abstract
The development of a prominent Middle Devonian Eifelian and an Upper Devonian Frasnian ostracode faunal sequence of western Canada is used to trace their evolutionary pathways, to illustrate evolutionary dynamics, and to evaluate the most probable causes and implications of the major and minor changes, which are clearly expressed in two sets of charts. A connection between sedimentary transgressive–regressive and evolutionary cycles is evident and documented in sample-for-sample accounts. Major changes in sea level were the primary cause for the most obvious breaks and trends in the faunal sequences and were responsible for the cyclic development of both the sedimentary and ostracode records. In contrast, numerous subordinate faunal breaks impart a distinctly punctuated pattern to both extinction and speciation pathways. Their regular spacing point to rhythmic influences that are interpreted to reflect primarily temperature fluctuations to which ostracodes are known to react in direct and indirect ways. In turn, the periodicity of the changes falls within the time frame of the Milankovitch Effect or to any one, or a combination, of its three variables. By combining the overall cyclic development with the punctuated progression of both extinction and speciation events in an "event-stratigraphic chart," a blueprint of the evolutionary dynamics emerges, which can be directly applied in sequence-stratigraphic reconstructions.On se sert du développement d'une séquence proéminente de faune ostracode dans l'ouest canadien, Eifélien au Dévonien moyen et Frasnien au Dévonien supérieur, pour en tracer les voies évolutives, illustrer la dynamique évolutive et pour évaluer les causes et les implications les plus probables des changements majeurs et mineurs qui sont clairement démontrés dans deux séries de diagrammes. Un lien entre les cycles sédimentaires de transgression–régression et d'évolution est évident et documenté dans des décomptes échantillon par échantillon. Des changements majeurs du niveau de la mer ont été la cause primaire des plus évidentes coupures et tendances des séquences fauniques et ils sont responsables du développement cyclique des sédiments et des ostracodes. Par contre, de nombreuses coupures dans la faune subordonnée donnent un patron nettement intermittent à la fois aux voies d'extinction et de spéciation. L'espacement régulier indique des influences rythmiques qui sont interprétées surtout comme le reflet des fluctuations de température auxquelles on sait que les ostracodes réagissent de façon directe et indirecte. Toutefois, la périodicité des changements tombe à l'intérieur de la période de temps de l'effet Milankovitch ou à l'une de ses trois variables ou une combinaison de celles-ci. En combinant le développement cyclique global et la progression intermittente des événements d'extinction et de spéciation dans un diagramme « événement-stratigraphie », il en ressort un plan directeur de la dynamique évolutive qui peut être directement appliqué aux reconstructions de séquences stratigraphiques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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- 2001
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25. Application of fuzzy cluster analysis to Lake Simcoe crustacean zooplankton community structure.
- Author
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Nicholls, Kenneth H. and Tudorancea, Claudiu
- Subjects
FUZZY sets ,CRUSTACEA ,ZOOPLANKTON - Abstract
Proposes the use of fuzzy cluster membership weights for ranking species important in a classification of the sampling unit, using crustacean-zooplankton data from Lake Simcoe in Ontario. Identification of elements of interannual and spatial variability in the crustacean zooplankton; Other aspects of crustacean zooplankton community structure.
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- 2001
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- View/download PDF
26. The impacts of broadcast burning after clear-cutting on the diversity of ectomycorrhizal fungi associated with hybrid spruce seedlings in central British Columbia.
- Author
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Mah, Karen, Tackaberry, Linda E., Egger, Keith N., and Massicotte, Hugues B.
- Subjects
CLEARCUTTING ,BIODIVERSITY ,ECTOMYCORRHIZAS ,SEEDLINGS - Abstract
Determines the effects of broadcast burning after clear-cutting on the diversity of ectomycorrhiza (ECM) on hybrid spruce seedlings in British Columbia. Abundance of Amphinema in planted seedlings from cut-burned and clear-cut sites; Relationship between mycorrhizal diversity and disturbance; Identification of fungal symbionts.
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- 2001
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27. Introduction / Introduction.
- Author
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Mavinic, Don and Zytner, Richard
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ENVIRONMENTAL engineering ,ENVIRONMENTAL protection - Abstract
Introduces a series of articles on environmental engineering in Canada.
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- 2001
28. Environmental engineering education in Canada.
- Author
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Smith, Daniel W and Biswas, Nihar
- Subjects
- *
ENVIRONMENTAL engineering , *ENVIRONMENTAL engineers , *ENVIRONMENTAL protection , *AIR quality management - Abstract
Environmental engineering education has been an active option for engineers from all disciplines for nearly 50 years at the graduate level. Some graduate programs expanded to integrate students with undergraduate science degrees with the engineering programs, since the cross discipline interaction is required outside the academic programs. In the mid-1980s interest increased to such a level that undergraduate programs began to form. Several of these programs have been accredited in their various forms recognizing the diversity of the field and those presenting the programs. The progression from graduate-degree-based specializations to broad-based undergraduate programs reflects both the increased knowledge in the field and the increased demand for professional engineers capable of responding to public health and environmental protection issues. Graduate programs greatly expand fundamental knowledge of physical, chemical, and biological processes and their application to protection problems. Of course, the doctorate is dedicated to the development of significant new knowledge. This paper defines several of the basic components of the environmental engineering profession and the educational process needed to produce qualified environmental engineers. [ABSTRACT FROM AUTHOR]
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- 2001
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29. Wet–dry composting of organic municipal solid waste: current status in Canada.
- Author
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Otten, Lambert
- Subjects
COMPOSTING ,WASTE products ,ENVIRONMENTAL engineering ,INDUSTRIAL wastes - Abstract
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.)
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- 2001
- Full Text
- View/download PDF
30. Bioremediation of diesel fuel contaminated soil.
- Author
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Zytner, R G, Salb, A, Brook, T R, Leunissen, M, and Stiver, W H
- Subjects
BIOREMEDIATION ,DIESEL fuels ,SOIL pollution ,CARBON dioxide - Abstract
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.)
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- 2001
- Full Text
- View/download PDF
31. Risk assessment for environmental contamination: an overview of the fundamentals and application of risk assessment at contaminated sites.
- Author
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Cushman, David J, Driver, Keith S, and Ball, Stephen D
- Subjects
ENVIRONMENTAL engineering ,RISK assessment ,PUBLIC health ,POLLUTANTS - Abstract
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.)
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- 2001
- Full Text
- View/download PDF
32. Choosing a "best" Canadian environmental management strategy.
- Author
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Heathcote, Isobel W
- Subjects
ENVIRONMENTAL management ,ENVIRONMENTAL law ,POLLUTION prevention ,ENVIRONMENTAL engineering - Abstract
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.)
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- 2001
- Full Text
- View/download PDF
33. A comparative [sup 40] Ar/[sup 39] Ar conventional and laserprobe study of muscovite from the Port Mouton pluton, southwest Nova Scotia.
- Author
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Fallon, Raymond P, Reynolds, Peter H, and Clarke, D Barrie
- Subjects
MUSCOVITE ,ARGON ,IGNEOUS intrusions ,EARTH sciences - Abstract
We report [sup 40] Ar/[sup 39] Ar age spectrum and laserprobe data for primary magmatic or fluido-magmatic muscovite minerals from the Port Mouton pluton, one of several weakly peraluminous peripheral plutons in the Meguma terrane, southwestern Nova Scotia. Laserprobe data from the cores of thin grain fragments suggest that this pluton cooled rapidly following intrusion at 373 ± 1 Ma, the U–Pb monazite age. The rims of thicker more complete grains record ages of 315–325 Ma, even in cases where there have been no apparent changes in grain rim chemistry and where deformation is minimal. The observed age gradients may be the result of prolonged reheating during the Late Carboniferous Alleghanian Orogeny or, alternatively, the result of rapid cooling at this time to temperatures below the closure value for muscovite rims. Conventional age spectra obtained from muscovite separates record neither the older intrusion age nor the younger reset–cooling age. Instead, these intermediate ages appear to reflect the averaging of intragrain (core–rim) age variations in thick grains and thus have no chronological significance. For these Port Mouton muscovite minerals, the record of initial cooling appears to reside only in certain limited regions of a given grain, a record that can be recovered by the laserprobe technique applied to carefully prepared subgrain fragments. A contrast in the early tectono-thermal histories of plutonic rocks in southwestern Nova Scotia relative to those in the northeast may be the result of perturbation by a mantle plume.Nous rapportons des données de sonde à laser et de plage d'âge [sup 40] Ar/[sup 39] Ar pour des muscovites primaires magmatiques ou de fluides magmatiques provenant du pluton de Port Mouton, un parmi plusieurs plutons périphériques faiblement hyperalumineux dans le terrane de Meguma, au sud-ouest de la Nouvelle-Écosse. Les données de sondes à laser du centre de fragments à grain mince suggèrent que ce pluton s'est refroidi rapidement après son intrusion il y a 373 ± 1 Ma, soit l'âge de la monazite U–Pb. Les bordures de grains plus épais et plus complets enregistrent des âges de 315–325 Ma, même dans les cas où il n'y a aucun changement apparent dans la chimie du bord du grain et où la déformation est minimale. Les gradients d'âges observés peuvent être le résultat d'un réchauffement prolongé au cours de l'orogenèse alléghanienne au Carbonifère tardif ou, alternativement, le résultat d'un refroidissement rapide à cette époque à des températures sous la valeur limite pour les bordures de muscovite. Les spectres d'âge conventionnels obtenus de feuillets de muscovite n'enregistrent ni l'âge de l'intrusion la plus vieille ni l'âge plus jeune de reprise/refroidissement. Ces âges intermédiaires semblent plutôt refléter la moyenne de variations d'âges intra-grains (centre–bordure) dans les grains épais et ainsi n'ont aucune signification chronologique. Pour ces muscovites de Port Mouton, l'enregistrement du refroidissement initial semble ne résider que dans certaines régions limitées d'un grain donné, une donnée qui peut être déterminée par la technique de la sonde à laser appliquée à des fragments soigneusement préparés de sous-grains. Un contraste dans les historiques tectono-thermiques précoces des roches plutoniques dans le sud-ouest de la Nouvelle-Écosse par rapport à celles au nord-est peut découler d'une perturbation par un panache du manteau.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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- 2001
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34. U-Pb ages of granitoid rocks in the northwestern Makkovik Province, Labrador: evidence for 175 million years of episodic synorogenic and postorogenic plutonism.
- Author
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Ketchum, John WF, Barr, Sandra M, Culshaw, Nicholas G, and White, Chris E
- Subjects
ROCKS ,ZIRCON ,IGNEOUS intrusions ,GEOLOGY ,EARTH sciences - Abstract
New U–Pb zircon, titanite, and monazite ages reported here, along with existing age data, demonstrate that granitoid bodies in the northwestern segment of the Paleoproterozoic Makkovik Province, Labrador, are of three distinct ages. The redefined Island Harbour Bay plutonic suite consists of varied dioritic to granitic units that were syntectonically emplaced into Archean crust of the Kaipokok domain between ca. 1895 Ma and 1870 ± 2 Ma. This plutonism occurred during the early stages of the Makkovikian Orogeny in an obliquely convergent, Andean continental margin setting. The Hares Islands and Drunken Harbour granites form smaller, discrete plutons that were emplaced in or adjacent to the Island Harbour Bay plutonic suite at 1805 ± 5 Ma and 1791 ± 2 Ma, respectively, during dextral strike-slip deformation that accompanied accretion of an outboard juvenile terrane. Magmatic activity during this period was preferentially sited along active structural zones, but also occurred outside of these zones. The undeformed Blacklers Bight A-type granite was emplaced in the Kaipokok domain at 1716 ± 1 Ma, late in the development of the orogen. A-type granites of this age form a significant component of the southeastern Makkovik Province, and their generation is linked to mafic underplating and heterogeneous regional extension. The new age data support the conclusion of earlier workers that crustal growth via synorogenic and postorogenic plutonism was episodic, and allow, along with field and geochemical data, inferences to be made regarding the tectonic setting of individual plutonic events.Les nouveaux âges U–Pb sur du zircon, de la titanite et de la monazite, rapportés ici avec certaines données d'âge déjà existantes, démontrent que des amas granitoïdes dans le segment nord-ouest de la province de Makkovik, du Paléoprotérozoïque, au Labrador, sont de trois âges distincts. La suite plutonique Island Harbour Bay redéfinie comprend des unités dioritiques à granitiques variées qui ont été mises en place syntectoniquement dans la croûte archéenne du domaine Kaipokok il y a environ 1895 à 1870 ± 2 Ma. Ce plutonisme a eu lieu au cours des premiers stages de l'orogénie makkovikienne dans un environnement de marge continentale andin à convergence oblique. Les granites de Hares Islands et de Drunken Harbour forment de plus petits plutons distincts qui ont été mis en place dans la suite plutonique Island Bay Harbour ou adjacents à cette dernière respectivement à 1805 ± 5 Ma et 1791 ± 2 Ma, au cours d'une déformation dextre qui a accompagné l'accrétion d'un terrane juvénile extérieur. L'activité magmatique au cours de cette période était localisée surtout le long de zones structurales actives mais elle a aussi eu lieu en dehors de ces zones. Blacklers Bight, le granite non déformé de type A, a été mis en place dans le domaine de Kaipokok ca. 1716 ± 1 Ma, soit tard dans le développement de l'orogène. Des granites de type A de cet âge sont une composante significative de la province Makkovik du sud-est et leur génération est liée à une remontée de magma mafique sous les plaques et à une extension hétérogène régionale. Les nouvelles données d'âge supportent les conclusions de travailleurs précédents à savoir que la croissance de la croûte par du plutonisme syn- et post orogénique était épisodique et permettaient, avec les données de terrain et géochemiques, de tirer des conclusions sur l'environnement tectonique d'événements plutoniques individuels.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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- 2001
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35. Integrated chitinozoan, conodont, and graptolite biostratigraphy from the upper part of the Cape Cormorant Formation (Middle Ordovician), western Newfoundland.
- Author
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Albani, Roberto, Bagnoli, Gabriella, Maletz, Jörg, and Stouge, Svend
- Subjects
EVENT stratigraphy ,GRAPTOLITES ,GEOLOGICAL basins ,GEOLOGY ,EARTH sciences - Abstract
The Cape Cormorant Formation of the Table Head Group exposed on the Port au Port Peninsula, western Newfoundland, is composed of dark-brown to black shales with interbeds of thin calcareous silty and sandy distal turbidites. Distinctive carbonate conglomerates and breccias derived from the foundering shelf are occasionally found in the formation. The sediments accumulated in the foreland basin formed during the early stage of the Taconic orogeny. The faunas from the upper part of the Cape Cormorant Formation include graptolites, conodonts, and chitinozoans. The graptolites are well preserved, but are of low diversity and are referred to the Darriwil Pterograptus elegans Zone. Conodonts recorded from the distal turbidites are rare and fragmented. The faunas include taxa that are known from the St. George and Table Head groups. The conodont fauna is tentatively assigned to the Histiodella kristinae Phylozone and to the younger, unzoned interval. The chitinozoans are well preserved and the yield is high. The fauna is assigned to the Cyathochitina jenkinsi Zone and to an undefined interval. The abundance and diversity of the chitinozoan assemblages display a cyclic pattern, which is related to changes of the oceanic watermass in the foreland basin. The new chitinozoan species Belonechitina nevillensis n. sp., Belonechitina uniformipunctata n. sp., and Cyathochitina cormorani n. sp. are described.La Formation de Cape Cormorant du Groupe de Table Head affleurant dans la péninsule de Port au Port, dans l'ouest de Terre-Neuve, est composée de schistes argileux brun foncé à noirs avec de minces interlits de turbidites distales, calcareuses, silteuses et sablonneuses. Des brèches et des conglomérats à carbonate distinctifs et dérivés de la plate-forme en effondrement se retrouvent occasionnellement dans la formation. Les sédiments se sont accumulés dans le bassin d'avant-pays qui s'est formé au cours du premier stage de l'orogénie taconique. La faune de la partie supérieure de la Formation de Cape Cormorant comprend des Graptolites, des Conodontes et des Chitinozoaires. Les Graptolites sont bien conservés, mais faiblement diversifiés, et ils sont rattachés à la zone Pterograptus elegans de Darriwil. Les Conodontes provenant de turbidites distales sont rares et fragmentés. La faune comprend des taxons qui sont connus des groupes de St. George et de Table Head. La faune des Conodontes est provisoirement assignée à la phylozone Histiodella kristinae et à l'intervalle plus jeune qui n'est pas zoné. Les Chitinozoaires sont bien préservés et abondants. La faune est assignée à la zone Cyathochitina jenkinsi et à un intervalle indéfini. L'abondance et la diversité des assemblages de Chitinozoaires démontrent un patron cyclique qui est relié aux changements de la masse d'eau océanique dans le bassin d'avant-pays. On décrit les nouvelles espèces de Chitinozoaires Belonechitina nevillensis n. sp., Belonechitina uniformipunctata n.sp. et Cyathochitina cormorani n. sp. [ABSTRACT FROM AUTHOR]
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- 2001
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36. Geology and tectonic setting of Paleoproterozoic granitoid suites in the Island Harbour Bay area, Makkovik Province, Labrador.
- Author
-
Barr, S M, White, C E, Culshaw, N G, and Ketchum, J WF
- Subjects
GEOLOGY ,PLATE tectonics ,ROCKS ,EARTH sciences - Abstract
Paleoproterozoic granitoid rocks in the Island Harbour Bay area (Kaipokok domain, Makkovik Province, Labrador) are divided into four separate suites on the basis of field relations, petrology, and age. The redefined Island Harbour Bay plutonic suite consists of ca. 1895–1870 Ma dioritic to granitic (mainly granodioritic and granitic) units. The rocks are variably foliated as a result of emplacement under amphibolite-facies conditions in a dextral transpressive regime during Andean-type subduction. The dominant mafic mineral is biotite, and accessory epidote, allanite, and titanite are abundant. The suite is calc-alkalic, but with rare-earth element patterns similar to those of Archean tonalitic–trondhjemitic–granodioritic suites. It is interpreted to have formed deep in an Andean-type magmatic arc at the margin of the Nain continent. In contrast, the younger Hares Islands and Drunken Harbour granites (emplaced at ca. 1805 and 1790 Ma, respectively) were part of widespread late-orogenic magmatic activity in the Makkovik Province. In contrast to the Island Harbour Bay plutonic suite, these units retain igneous textures and are either unfoliated or display magmatic foliation, locally modified by emplacement in active shear zones. The ca. 1716 Ma Blacklers Bight granite varies from porphyritic to equigranular, is fluorite-bearing, and has chemical features approaching those of continental A-type granites. Similar granite occurs farther south in the Makkovik Province, reflecting widespread anorogenic magmatic activity at that time, perhaps related to mafic magma underplating. Variable interaction with Archean (Nain Province) crust by granitic magmas of all three ages is evidenced by ℇ[sub Nd ] values ranging from –7.2 to –2.5.Les roches granitoïdes paléoprotérozoïques de la région de Island Harbour Bay (domaine de Kaipokok, province de Makkovik, au Labrador) sont divisées en quatre suites distinctes selon les relations de terrain, la pétrologie et l'âge. La suite plutonique redéfinie de Island Habour Bay est composée d'unités dioritiques à granitiques (surtout granodioritiques et granitiques), ca. 1895-1870 Ma. La foliation des roches est variable en raison de leur mise en place sous des conditions de faciès de l'amphibolite dans un régime transpressif dextre durant une subduction de type andin. Le minéral mafique dominant est la biotite; l'épidote, l'allanite et la titanite abondent en tant que minéraux accessoires. La suite est calc-alkaline, mais elle possède des patrons des éléments des terres rares semblables à ceux des suites tonalite–trondhjemite–granodiorite de l'Archéen. On croit qu'elle s'est formée à grande profondeur dans un arc magmatique de type andin en bordure du continent Nain. À titre de comparaison, les granites plus jeunes de Hares Island et de Drunken Harbour (respectivement mis en place il y a environ 1805 et 1790 Ma) faisaient partie d'une vaste activité magmatique tardi-orogénique dans la province de Makkovik. Contrairement à la suite plutonique Island Harbour Bay, ces unités ont conservé des textures ignées et elles sont soit sans foliation ou soit avec foliation magmatique, modifiée localement par la mise en place de zones de cisaillement actives. Le granite de Blacklers Bight, ca. 1716 Ma, varie de porphyrique à isogranulaire, il comporte de la fluorine et possède des caractéristiques qui rappellent celles des granites de type A. On retrouve un granite semblable plus au sud dans la province de Makkovik, démontrant qu'à cette époque il y avait une activité magmatique anorogénique généralisée, possiblement reliée à une remontée de magma mafique sous les plaques. L'interaction variable entre la croûte archéenne (province de Nain) et les magmas granitiques des trois âges est mis en évidence par les valeurs de ℇ[sub Nd] variant de –7,2 à –2,5.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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- 2001
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37. Natural fire frequency for the eastern Canadian boreal forest: consequences for sustainable forestry.
- Author
-
Bergeron, Yves, Gauthier, Sylvie, Kafka, Victor, Lefort, Patrick, and Lesieur, Daniel
- Subjects
FOREST fires ,FOREST management - Abstract
Examines the natural fire frequency in boreal forest in Canada. Decrease in forest fires; Consequences of fire cycle for sustainable forest management of the boreal forest; Justification of clear-cutting practices; Elongation of the fire cycles.
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- 2001
- Full Text
- View/download PDF
38. Extracting a paleotemperature record from picea engelmannii tree-line sites in the central Canadian Rockies.
- Author
-
St. George, Scott and Luckman, Brian H.
- Subjects
PALEOTHERMOMETRY ,ENGELMANN spruce - Abstract
Examines the paleotemperature record from Picea engelmannii tree-line sites in Canadian Rockies, British Columbia. Differences in tree species modelling techniques, spatial coverage and seasonal temperatures; Development of temperature reconstruction for the Banff-Jasper region; Regional estimates of temperature.
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- 2001
- Full Text
- View/download PDF
39. Recent growth of conifer species of western North America: assessing spatial patterns of radial growth trends.
- Author
-
McKenzie, Donald, Hessl, Amy E., and Peterson, David L.
- Subjects
FOREST fires ,CARBON - Abstract
Examines the direct emissions of carbon from forest fires in Canada. Mean area-weighted fuel consumption for fires; Changes to the forest sink condition; Mean annual estimate for direct carbon emissions.
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- 2001
- Full Text
- View/download PDF
40. Functional and numerical responses of predators to cyclic lemming abundance: effects on loss of goose nests.
- Author
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Wilson, Deborah J. and Bromley, Robert C.
- Subjects
GEESE ,EGGS ,PREDATORY animals - Abstract
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.)
- Published
- 2001
- Full Text
- View/download PDF
41. Bryophyte community structure in a boreal poor fen: reciprocal transplants.
- Author
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Mulligan, Roisín C and Gignac, L Dennis
- Subjects
PEAT mosses ,BRYOPHYTES ,NONVASCULAR plants ,PEATLANDS - Abstract
The ability of four boreal bryophytes (Sphagnumangustifolium (C. Jens ex Russ.), Sphagnum fuscum (Schimp.) Klinggr., Sphagnum magellanicum Brid., and Pleurozium schreberi (Brid.) Mitt.) to live in each others' habitats was examined in a 1-year reciprocal transplant experiment conducted in a poor fen peatland in northern Alberta, Canada. Growth in length was determined by measuring increase in shoot length, and growth in dry weight was determined by subtracting final dry weight from initial predicted dry weight. Species tolerance ranges, which approximate to fundamental niches, were determined by the significant differences in growth among the species. Stepwise regression analyses indicated that depth to water was the most important factor for all species except S. fuscum. Pleurozium schreberi exhibited the narrowest potential distribution, indicating that its present distribution is likely the result of habitat limitation. Although S. magellanicum and S. angustifolium exhibited wide potential ecological amplitude, the distributions of these species are partially limited by habitat. Sphagnum fuscum was able to grow in all habitats, and its distribution is not limited by any of the habitat factors measured.Key words: peatland, moss, community structure, Sphagnum, Pleurozium schreberi, niche.Les auteurs ont étudié la capacité de quatre bryophytes boréales (Sphagnum angustifolium (C. Jens. ex Russ.), Sphagnum fuscum (Schimp.) Klinggr., Sphagnum magellanicum Brid. et Pleurozium schreberi (Brid.) Mitt.) à vivre dans les habitats les uns des autres, au cours d'une année de transplantations expérimentales réciproques conduites dans une tourbière minérotrophe pauvre du nord de l'Alberta, au Canada. Ils ont déterminé la croissance en longueur en mesurant l'augmentation de la longueur des tiges, et la croissance en poids sec, en soustrayant le poids sec final du poids sec initial prédit. Les amplitudes de tolérance des espèces, qu'on peut considérer comme niche fondamentale, sont déterminées par les différences de croissance significatives observées entre les espèces. Les analyses par régression progressive indiquent que la profondeur de l'eau est le facteur le plus important pour toutes les espèces, sauf pour le S. fuscum. Le Pleurozium schreberi montre la distribution potentielle la plus étroite, ce qui indique que sa distribution actuelle est le résultat d'une limitation dans l'habitat. Bien que le S. magellanicum et le S. angustifolium montrent une large amplitude écologique potentielle, les distributions de ces espèces sont partiellement limitées par l'habitat. Le S. fuscum est capable de croître dans tous les habitats et sa distribution n'est pas limitée par les variables de l'habitat qui on ét é mesurées.Mots clés: tourbière, mousse, structure des communautés, Sphagnum, Pleuroziumschreberi, habitat. [ABSTRACT FROM AUTHOR]
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- 2001
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42. Dynamics and morphology of giant circular patterns of low tree density in black spruce stands in northern Quebec.
- Author
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Giroux, Jean-François, Bergeron, Yves, and Veillette, Jean J
- Subjects
BLACK spruce ,GEOMORPHOLOGY ,PLANTS ,SOILS - Abstract
Giant circular patterns of low tree density in black spruce (Picea mariana) stands were investigated in the Abitibi region of Quebec. We used dendrochronological techniques to test the hypotheses that ring patterns of low tree density are caused either by radial changes in spruce mortality or productivity. Seven circles were sampled. We found no gradient in the age of spruce along circle radii suggesting that rings of low tree density do not expand radially, that is, they are not spatially dynamic entities. The results indicate, however, that spruce trees were less dense and productive within the rings due to excessive moisture in the soil. Measurements of surface elevation, thickness of the organic layer and elevation of the mineral substrate across the circles revealed that a depression in the mineral soil beneath the rings traps the surface water and this area of poor drainage seems to prevent the establishment of black spruce within the rings. The origin of the ring-shaped depressions was attributed to geological or geomorphological causes.Key words: black spruce, Picea mariana, mortality, productivity, rings, geomorphology.Des formations circulaires géantes caractérisées par une densité arborescente faible ont été étudiées dans des peuplements d'épinettes noires (Picea mariana) de l'Abitibi au Québec. Les hypothèses liées à un processus de mortalité radiale ou à une baisse de productivité dans l'anneau ont été documentées dans sept cercles à l'aide de techniques dendrochronologiques. L'absence d'un gradient d'âge des épinettes ne supporte pas une expansion radiale des anneaux. Par contre, les résultats indiquent que la productivité et la densité des épinettes sont plus faibles dans l'anneau à cause de l'humidité excessive du sol à cet endroit. Des relevés topographiques de la surface du sol, de l'épaisseur de la couche organique et de l'altitude du substrat minéral ont démontré l'existence d'une dépression dans le sol minéral sous l'anneau. Cette dépression, dans un environnement comme celui-ci où la nappe phréatique est près de la surface, piège les eaux de surface et maintient l'humidité excessive du sol prévenant ainsi l'établissement de l'épinette noire. Les anneaux sont donc statiques et l'origine de la dépression annulaire relève de causes géologiques ou géomorphologiques.Mots clés : épinette noire, Picea mariana, mortalité, productivité, anneau, géomorphologie. [ABSTRACT FROM AUTHOR]
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- 2001
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43. Autecology of Erythronium grandiflorum in western Canada.
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Loewen, Dawn C, Allen, Geraldine A, and Antos, Joseph A
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ERYTHRONIUM (Plants) ,LILIACEAE ,PLANT physiology - Abstract
Habitat requirements of the yellow glacier lily, Erythronium grandiflorum Pursh, were studied at 38 sites in southern British Columbia and southwestern Alberta. At each site we recorded densities of E. grandiflorum growth stages from seedling to flowering, environmental characteristics of the site, and percent cover of associated plant species. We carried out detrended correspondence analysis (DCA) of the sites based on cover of associated species, and examined rank correlations between site environmental variables and site ordination scores. Variation among sites was related primarily to elevation and the presence of deciduous vs. coniferous trees. All growth stages of E. grandiflorum were less abundant in coniferous forests than in open areas or sites with deciduous trees, suggesting that evergreen canopies restrict the species on many sites where it could otherwise grow. Although E. grandiflorum populations were most commonly found in subalpine meadows, they flowered more abundantly in low-elevation populations. Recruitment was frequent, with seedlings occurring at many sites; we also showed that detached bulb segments can give rise to new ramets. The present widespread distribution of E. grandiflorum may derive from a post-glacial period with extensive meadow habitat that was favourable for rapid spread.Key words: canopy cover, elevation, yellow glacier lily, post-glacial migration, subalpine meadows.Les auteurs ont étudié les caractéristiques des habitats nécessaires au lis jaune des glaciers, l'Erythronium grandiflorum Pursh, sur 38 sites du sud de la Colombie Britannique et du sud-ouest de l'Alberta. Sur chaque site, ils ont enregistré la densité des stades de développement des E. grandiflorum, de la plantule à la floraison, ainsi que les caractéristiques environnementales du site, et le pourcentage de couverture des plantes associées. Ils ont effectué des analyses par correspondances hors-tendances (DCA) des sites, basées sur la couverture des espèces associée, et ils ont examiné l'ordination des corrélations entre les variables environnementales du site et les données d'ordination du site. La variations entre les sites est surtout reliée à l'élévation et à la présence d'arbres décidus vs des conifères. Tous les stades de développement de l'E. grandiflorum sont moins abondants dans les forêts conifériennes que sur les stations ouvertes, ou les sites avec des arbres décidus, ce qui suggère que les canopées conifériennes restreignent l' espèces sur plusieurs sites où elle pourrait par ailleurs se développer. Bien que les populations de l'E. grandiflorum se retrouvent plus communément dans les prairies sub-alpines, elles fleurissent plus abondamment dans les populations de basses élévations. Le recrutement est fréquent, avec la présence de plantules sur plusieurs sites; les auteurs montrent également que des segments de bulbes détachés peuvent donner de nouvelles ramètes. La large distribution actuelle de l'E, grandiflorum pourrait provenir de la période post-glaciaire comportant de grands habitats de prairie, ce qui était favorable à une rapide dispersion.Mots clés : canopée, élévation, lis jaune des glaciers, migration post-glaciaire, prairies sub-alpines.[Traduit par Rédaction] [ABSTRACT FROM AUTHOR]
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- 2001
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44. Imbricate architecture of the upper Paleozoic to Jurassic oceanic Cache Creek Terrane, central British Columbia.
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Struik, L C, Schiarizza, P, Orchard, M J, Cordey, F, Sano, H, MacIntyre, D G, Lapierre, H, and Tardy, M
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SUBMARINE topography ,OCEANIC plateaus ,ROCKS ,RIVERS - Abstract
Upper Paleozoic to Lower Jurassic oceanic rocks of the Cache Creek Terrane near Fort St. James, in central British Columbia, form a stack of thrust sheets cut by steeply dipping strike-slip faults. Paleontologically dated upper Paleozoic strata include bioclastic shallow-water limestone and ribbon chert. Isotopically dated Permian rocks consist of tonalite sills and stocks and rhyolite flows intercalated with basalt flows. Paleontologically dated lower Mesozoic rocks include greywacke, sandstone, siltstone, argillite, ribbon chert, conglomerate, limestone, and basalt tuff. Trembleur Ultramafite unit of the Cache Creek Complex, in places part of an ophiolite suite, forms thrust sheets and klippen that overlie lower Mesozoic sedimentary rocks. Sedimentological, lithochemical, paleontological, petrological, and textural comparisons with other areas and established models demonstrate that Cache Creek Terrane is an accretionary complex, a structurally stacked assemblage of rocks that originated in diverse and disparate oceanic paleoenvironments. These environments include spreading ridge, oceanic plateau, atoll, trench fill, and possibly arc. Internal imbrication of the terrane is as young as Early Jurassic, as determined from fossil evidence, and the minimum age of obduction of the thrust stack westward onto Stikine Terrane is Middle Jurassic, as determined from dating of a crosscutting pluton. Triassic blueschist and eclogite of Cache Creek Terrane are interpreted to have been primarily uplifted to upper crustal levels during Triassic subduction. Cache Creek Terrane, as a remnant of that subduction process, and caught in the collision between Stikine and Quesnel terranes, marks the position of a lithosphere-scale suture zone, the Pinchi Suture.Les roches océaniques du terrane de Cache Creek (Paléozoïque supérieur à Jurassique inférieur), près de Fort St. James, au centre de la Colombie-Britannique forment un empilement de nappes de charriage recoupé par des failles de décrochement à pendage abrupt. Les strates du Paléozoïque supérieur, datées par la paléontologie, comprennent des calcaires bioclastiques d'eau peu profonde et des cherts rubanés. Les roches du Permien, datées par analyse isotopique, comprennent des filons-couches et des petits intrusifs de tonalite ainsi que des écoulements de rhyolite intercalés avec des écoulements de basaltes. Les roches du Mésozoïque inférieur, datées par la paléontologie, comprennent des grauwackes, des grès, des microgrès, des argilites, des cherts rubanés, des conglomérats, des calcaires et des tufs basaltiques. L'unité ultramafique Trembleur du complexe de Cache Creek, qui à certains endroits fait partie d'une suite ophiolitique, forme des nappes de charriage et des klippes qui reposent sur les roches sédimentaires du Mésozoïque inférieur. Des comparaisons sédimentologiques, lithochimiques, paléontologiques, pétrologiques et texturales avec d'autres régions et avec des modèles établis démontrent que le terrane de Cache Creek est un complexe formé par accrétion, un assemblage de roches empilées structurellement qui proviennent de paléoenvironnements divers et disparates. Ces environnements océaniques comprennent des crêtes qui s'écartent, des plateaux océaniques, des atolls, des remplissages de fosses et possiblement des arcs. Une imbrication interne du terrane s'est effectuée aussi tôt que le Jurassique précoce, tel qu'il a été déterminé par des évidences de fossiles, et l'âge minimum pour l'obduction de l'empilement de charriage vers l'ouest sur le terrane de Stikine serait du Jurassique moyen, tel que déterminé par la datation d'un pluton qui le recoupe. Le schiste bleu et l'éclogite du terrane de Cache Creek (du Trias) sont interprétés comme ayant été principalement soulevés à des niveaux supérieurs de la croûte au cours de la subduction au Trias. Le terrane de Cache Creek, en tant que lambeau de ce processus de subduction pris dans la collision entre les terranes de Stikine et Quesnel, marque la position d'une zone de suture à l'échelle de la lithosphère, soit la suture Pinchi.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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45. The influence of mantle plume in the genesis of the Cache Creek oceanic igneous rocks: implications for the geodynamic evolution of the inner accreted terranes of the Canadian Cordillera.
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Tardy, M, Lapierre, H, Struik, L C, Bosch, D, and Brunet, P
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MANTLE plumes ,EARTH'S mantle ,PLUMES (Fluid dynamics) ,IGNEOUS rocks - Abstract
West of Prince George, British Columbia, the Cache Creek Terrane is composed of mafic lavas interlayered with both mid-Permian pelagic limestones and Upper Triassic siliceous shales and greywackes. Gabbro, basalt, dolerites, and foliated clinopyroxene-rich ultramafic rocks are exposed within the Pinchi Fault system. The mid-Permian lavas show affinities of oceanic island tholeiites. Among the Triassic lavas, three types of rocks have been distinguished. Type 1 is geochemically similar to the mid-Permian volcanic rocks. Type 2 differs from type 1 by higher TiO[sub 2] abundances and convex rare earth element patterns. Type 3 has the highest Zr, Nb, and Ta abundances and the greatest light rare earth element enrichment. The mafic rocks within the Pinchi Fault system are similar to N-type mid-ocean-ridge basalt (N-MORB), and the foliated ultramafic rocks are characterized by very low trace element contents, similar to extremely depleted harzburgites. Permian lavas and Triassic type 1 and igneous rocks from the Pinchi Fault system have the highest e[sub Nd(i)] ratios (+7.4 to +9.6) and those of type 3 alkali have the lowest ratios (+2.0 to +5.3). The ℇ[sub Nd(i)] values of type 2 are intermediate between those of type 1 (~+7) and type 3 (~+4.9). This suggests that the Triassic rocks generated from a heterogeneous plume source or the mixing between depleted N-MORB and enriched oceanic island basalt sources. If the mafic igneous rocks sampled in central British Columbia are representative of the preserved parts of an oceanic crust, within the Cache Creek Terrane, then that crust was dominated by oceanic plateau components, perhaps due to the difficulty of subducting thick crust.À l'ouest de Prince George, en Colombie-Britannique, le terrane de Cache Creek est composé de laves mafiques interstratifiées avec des calcaires pélagiques du Permien moyen et des schistes argileux siliceux et des grauwackes du Trias supérieur. Dans le système de failles Pinchi, on retrouve des affleurements de gabbro, de basalte, de dolérite et de roches ultramafiques foliées et riches en clinopyroxène. Les laves du Permien moyen montrent des affinités avec des tholéiites d'îles océaniques. Parmi les laves du Trias, on distingue trois types de roches. La géochimie du type 1 est similaire à celle des roches volcaniques du Permien moyen. Le type 2 diffère du type 1 par de plus hautes concentrations de TiO[sub 2] et des patrons convexes pour les éléments des terres rares. Le type 3 a les plus grandes concentrations de Zr, Nb, et Ta et le plus grand enrichissement en éléments de terres rares légers. Les roches mafiques à l'intérieur du système de failles Pinchi sont similaires aux basaltes médio-océaniques normaux (N-MORB) alors que les roches ultramafiques foliées sont caractérisées par de très faibles contenus en éléments traces, semblables à des harzburgites extrêmement appauvries. Les laves du Permien, les roches ignées et celles de type 1 du Trias provenant du système de failles Pinchi ont les rapports ℇ[sub Nd(i)] les plus élevés (+7,4 à +9,6) alors qu'ils sont les plus bas pour les roches alcalines de type 3 (+2,0 à +5,3). Les valeurs ℇ[sub Nd(i)] du type 2 sont intermédiaires entre celles du type 1 (~+7) et du type 3 (~+4,9). Cela suggère que les roches du Trias proviennent d'une source panache hétérogène ou d'un mélange entre des basaltes N-MORB appauvris et des sources enrichies de basaltes d'îles océaniques. Si les roches mafiques échantillonnées au centre de la Colombie-Britannique. sont représentatives de parties préservées d'une croûte océanique, à l'intérieur du terrane de Cache Creek, alors cette croûte a été dominée par des composantes du plateau océanique, peut-être parce qu'il eut été difficile à une croûte épaisse de passer en dessous d'une autre plaque. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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46. Facies interpretation of Middle Carboniferous to Lower Permian Pope succession limestone of Cache Creek Group, Fort St. James, central British Columbia.
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Sano, H and Rui, L
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CARBONIFEROUS stratigraphic geology ,LIMESTONE ,CARBONATE rocks ,BASALT - Abstract
Lithostratigraphy and microfacies of the Bashkirian to Asselian Pope succession limestone of the Cache Creek Group near Fort St. James, central British Columbia, were lithologically grouped into five facies associations A to E. On the basis of fusulines and conodonts, facies associations A to D and the lower part of facies association E are time-equivalent, ranging from the lower Bashkirian to lower Kasimovian, and the upper part of facies association E is dated as upper Gzhelian to Asselian. The Pope succession limestone is interpreted to have been built on a basaltic basement of an oceanic plateau or seamount in an open-ocean realm. The limestone is devoid of terrigenous grains, is associated with basaltic rocks, and laterally grades into deeper-water spicular cherts. Microfacies analysis of facies associations A to E showed that they exhibit characteristic facies of (A) deep-water basinal setting, (B) marginal basin to lower slope, (C) shallow-subtidal bank margin, (D) peritidal algal mound on the bank margin, and (E) shallow-subtidal bank margin to intertidal lagoonal flat,. Moscovian to Asselian rocks of facies associations C, D, and E record an upward increase of low-relief encrusting calci-microbes as rock-builders. This tendency is closely correlated with that in limestone buildups mapped from the Panthalassan Ocean. The abundance of phylloid algal plates and the reefal facies of the Moscovian rocks of facies association D are the same as the reef-building phylloid algae of the Bashkirian to Sakmarian limestone of both the Tethyan and Panthalassan oceans. The Pope succession limestone has many similarities in tectonic, stratigraphic, sedimentologic, and paleontologic aspects to the Akiyoshi buildup, a representative Panthalassan buildup in a Permian subduction-related accretionary complex in Japan. The timing of the increasing importance of the calci-microbes and phylloid algae in the Pope and Akiyoshi buildups is also correlatable.La lithostratigraphie et les microfaciès de la séquence calcaire Pope, du Bashkirien à l'Asselien, du Groupe de Cache Creek à proximité de Fort St. James, au centre de la Colombie-Britannique, ont été regroupés, selon la lithologie, en cinq faciès associatifs, A à E. Basé sur les Fusulines et les Conodontes, les faciès associatifs A à D et la partie inférieure du faciès associatif E sont équivalents dans le temps, allant du Bashkirien inférieur au Kasimovien inférieur et la partie supérieure du faciès associatif E est daté du Gzelien supérieur à l'Asselien. La séquence calcaire Pope est interprétée comme ayant été construite sur le socle basaltique d'un plateau océanique ou sur un mont sous-marin dans un domaine de la haute mer. Le calcaire ne présente pas de grains terrigènes, il est associé à des roches basaltiques et passe latéralement à des cherts spiculaires d'eau plus profonde. L'analyse des microfaciès des faciès associatifs A à E démontre qu'ils présentent des faciès (A) d'environnement de bassin profond, (B) de bassin marginal à une pente inférieure, (C) de bord de la rive, peu profond, subtidal, (D) d'édifices algaires péritidaux sur les bords de la rive et (E) respectivement de bord de rive peu profond, subtidal, à bord de rive, intertidal, à battures lagunaires. Les roches des faciès associatifs C, D et E, du Moscovien à l'Asselien, enregistrent une augmentation vers le haut de microbes calcaires à bas relief d'incrustation en tant qu'édificateurs de roches. Cette tendance est étroitement reliée à l'accumulation de calcaire cartographiée dans l'océan panthalassien. La grande abondance de plaques algaires foliacées et le faciès récifal des roches du Moscovien du faciès associatif D sont identiques aux algues foliacées constructrices de récifs dans le calcaire des océans Tethys et Panthalassa, du Bashkirien au Sakmarien. Selon des aspects tectoniques, stratigraphiques, sédimentologiques et paléontologiques, la séquence calcaire Pope ressemble en plusieurs points à l'accumulation Akiyoshi, au Japon, une accumulation représentative panthalassienne dans un complexe accrétionnaire relié à la subduction, au Permien. Il est aussi possible de corréler le séquencement de l'augmentation de l'importance des microbes calcaires et des algues foliacées dans les accumulations Pope et Akiyoshi.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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47. Biostratigraphic and biogeographic constraints on the Carboniferous to Jurassic Cache Creek Terrane in central British Columbia.
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Orchard, M J, Cordey, F, Rui, L, Bamber, E W, Mamet, B, Struik, L C, Sano, H, and Taylor, H J
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CARBONIFEROUS stratigraphic geology ,PALEOZOIC stratigraphic geology ,CONODONTS ,RIVERS - Abstract
Conodonts, radiolarians, foraminiferids, and corals provide constraints on the geology and tectonics of the Nechako region. They also support the notion that the Cache Creek Terrane is allochthonous with respect to the North American craton. The 177 conodont collections, assigned to 20 faunas, range in age from Bashkirian (Late Carboniferous) to Norian (Late Triassic); 70 radiolarian collections representing 12 zones range from Gzhelian (Late Carboniferous) to Toarcian (Early Jurassic); 335 collections assigned to 11 fusulinacean assemblages (with associated foram-algal associations) range from Bashkirian to Wordian (Middle Permian); and two coral faunas are of Bashkirian and Wordian age. The fossils document a long but sporadic history of sedimentary events within the Cache Creek Complex that included two major carbonate buildups in the Late Carboniferous (Pope limestone) and Middle Permian (Copley limestone), punctuated by intervening Early Permian deepening; basaltic eruptions during the mid Carboniferous and mid Permian; the onset of oceanic chert sedimentation close to the Carboniferous–Permian boundary and its persistence through the Late Triassic (Sowchea succession); latest Permian and Early Triassic mixed clastics and volcanics (Kloch Lake succession); Middle and Late Triassic reworking of carbonates (Whitefish limestone), including cavity fill in older limestones (Necoslie breccia), and fine-grained clastic sedimentation extending into the Early Jurassic (Tezzeron succession). Tethyan, eastern Pacific, and (or) low-latitude biogeographic attributes of the faunas are noted in the Gzhelian (fusulines), Artinskian (conodonts, fusulines), Wordian (fusulines, corals, conodonts), and Ladinian (conodonts, radiolarians). The Cache Creek Terrane lay far to the west of the North American continent during these times.Les conodontes, radiolaires, foraminiféridés et les coraux améliorent les données géologiques et tectoniques de la région de Nechako. Ils appuient aussi la notion que le terrane de Cache Creek est allochtone par rapport au craton nord-américain. Cent soixante-dix-sept collections de conodontes, assignés à 20 faunes, ont des âges allant du Bashkirien (Carbonifère tardif) au Norien (Trias tardif); 70 collections de radiolaires représentant 12 zones vont du Gzelien (Carbonifère tardif) au Toarcien (Jurassique précoce); 335 collections assignées à 11 assemblages de fusulinides (avec des associations foraminifères-algues associées) vont du Bashkirien au Wordien (Permien moyen) et deux faunes coralliennes sont du Bashkirien et du Wordien. Les fossiles enregistrent un historique long mais sporadique d'événements sédimentaires à l'intérieur du complexe de Cache Creek qui comprend deux grandes formation carbonatées au Carbonifère tardif (calcaire Pope) et au Permien moyen (calcaire Copley) ponctuées par un nouvel approfondissement au Permien précoce; des éruptions basaltiques au cours du Carbonifère moyen et du Permien moyen; le déclenchement de la sédimentation océanique de chert près de la limite Carbonifère–Permien et sa persistance à travers le Trias tardif (séquence de Sowchea); des mélanges de clastiques et de volcaniques au Permien terminal et au Trias précoce (séquence de Kloch Lake); le remaniement des carbonates (calcaire de Whitefish) au Trias moyen et tardif, comprenant le remplissage de cavités dans des calcaires plus âgés (brèche de Necoslie) et une sédimentation clastique à grains fins se poursuivant jusqu'au Jurassique précoce (séquence de Tezzeron). Des attributs biogéographiques du genre téthysien, de l'est du Pacifique et (ou) de basse latitude, sont notés dans les faunes du Gzelien (Fusulines) de l'Artinskien (conodontes, fusulines), du Wordien (fusulines, coraux, conodontes) et du Ladinien (conodontes, radiolaires). Le terrane de Cache Creek était potentillement très éloigné à l'ouest du continent nord-américain durant ces époques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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48. Timing and tectonic setting of Stikine Terrane magmatism, Babine-Takla lakes area, central British Columbia.
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MacIntyre, D G, Villeneuve, M E, and Schiarizza, P
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- *
STRUCTURAL geology , *PHYSICAL geology , *MAGMATISM , *LAKES - Abstract
New bedrock mapping completed as part of the Nechako NATMAP Project indicates that the area between Babine and Takla lakes in central British Columbia is underlain by rocks of the Early Permian Asitka, Late Triassic Takla, and Early to Middle Jurassic Hazelton volcanic-arc assemblages of the Stikine Terrane. These are cut by large composite stocks of quartz diorite, granodiorite, and quartz monzonite previously mapped as the Late Triassic to Early Jurassic Topley intrusions. New U/Pb (n = 6) and laser [sup 40] Ar/[sup 39] Ar (n = 10) isotopic age dates reported in this paper suggest there are two distinct ages of plutons: the Topley intrusive suite with isotopic ages between 218 and 193 Ma; and, east of Babine Lake, the new Spike Peak intrusive suite with isotopic ages ranging from 179 to 166 Ma. West of the main plutonic belt is a thick volcanic succession of subaerial, porphyritic andesite flows, volcanic breccias, and rhyolitic ash-flow tuffs that have isotopic ages between 185 and 174 Ma. These rocks are assigned to the Saddle Hill Formation of the Hazelton Group. The plutonic roots of this proximal arc assemblage are most likely the coeval and compositionally similar plutons of the Spike Peak intrusive suite that have been unroofed in the area east of the Takla Fault. Major oxide and trace element data support the interpretation that the Topley and Spike Peak granitic rocks formed in a juvenile volcanic-arc environment and that magmatism is related to melts generated above a long-lived subduction zone of unknown orientation.Une nouvelle cartographie effectuée dans le cadre du projet NATMAP Nechako indique que la région entre les lacs Babine et Takla au centre de la Colombie-Britannique est recouverte de roches des assemblages d'arcs volcaniques du terrane de Stikine, soit Asitka du Permien précoce, Takla du Trias tardif et Hazelton du Jurassique précoce à moyen. Ces assemblages sont recoupés par des petits massifs intrusifs composites de diorite quartzique, de granodiorite et de monzonite quartzique qui avaient auparavant été cartographiés en tant que les intrusions Topley, du Trias tardif au Jurassique précoce. De nouvelles datations U-Pb (n = 6) et isotopes laser [sup 40] Ar/[sup 39] Ar (n = 10) présentées dans cet article suggèrent deux âges distincts de plutons, soit la suite intrusive de Topley avec des âges isotopiques entre 218 et 193 Ma et, à l'est du lac Babine, la nouvelle suite intrusive de Spike Peak dont les âges isotopiques varient de 179 à 166 Ma. À l'ouest de la ceinture plutonique principale se trouve une séquence volcanique épaisse d'écoulements subaériens d'andésite porphyrique, des brèches volcanique et des tufs d'écoulement de cendre rhyolitique dont les âges isotopiques varient entre 185 et 174 Ma. Ces roches sont assignées à la Formation de Saddle Hill du Groupe Hazelton. Les racines plutoniques de cet assemblage d'arc proximal sont fort probablement les plutons contemporains et à composition similaire de la suite intrusive de Spike Peak qui ont été décapés dans la région à l'est de la faille de Takla. Les données sur les principaux oxydes et les éléments traces corroborent l'interprétation que les roches granitiques de Topley et de Spike Peak se sont formées dans un environnement d'arc volcanique juvénile et que le magmatisme est relié aux fusions qui se sont produites au-dessus d'une ligne de subduction de longue durée mais dont l'orientation est inconnue.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
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49. New U–Pb age constraints on latest Cretaceous magmatism and associated mineralization in the Fawnie Range, Nechako Plateau, central British Columbia.
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Friedman, R M, Diakow, L J, Lane, R A, and Mortensen, J K
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MAGMATISM ,GEOLOGY ,NATURAL history ,EARTH sciences - Abstract
New U–Pb ages and K–Ar dates, primarily for rocks proximal to mineral occurrences in the Fawnie Range of central British Columbia, document latest Cretaceous (ca. 74–66 Ma) continental-arc igneous activity and date associated base and precious metal mineralization. U–Pb ages of ca. 73–69 Ma for the Capoose pluton and hypabyssal to extrusive garnet rhyolites at the Capoose prospect demonstrate a latest Cretaceous age for mineralization and a likely plutonic source for mineralizing fluids. A U–Pb age of ca. 67 Ma for a late mineralized felsic dyke and two K–Ar dates (ca. 70 and 68 Ma) for hornfelsed Jurassic volcanic rocks at the Blackwater–Davidson prospect constrain a latest Cretaceous age for mineralization. A U–Pb age of ca. 74 Ma for a fine grained diorite sill that cuts a significant epithermal gold vein at the Tsacha prospect places a minimum age on mineralization at this probable Jura-Cretaceous deposit and documents latest Cretaceous magmatism. Latest Cretaceous K–Ar dates are reported for an andesite flow adjacent to the Eocene Holy Cross deposit (ca. 66 Ma), about 35 km north of the Fawnie Range, and a Kasalka Group rhyolite (ca. 68 Ma) exposed near the western margin of the Nechako Plateau. Latest Cretaceous magmatism and mineralization in the Fawnie Range represent the waning stages of Bulkley suite magmatism and porphyry-style mineralization, which was concentrated along the western margin of the Nechako Plateau at circa 88–70 Ma. The distribution of latest Cretaceous arc igneous rocks along the North American Cordilleran is reviewed and tectonic implications discussed.De nouveaux âges U–Pb et de nouvelles datations K–Ar, surtout pour des roches à proximité d'occurrences minérales dans la chaîne Fawnie du centre de la Colombie-Britannique documentent la plus récente activité ignée d'arc continental au Crétacé (ca. 74–66 Ma) et datent la minéralisation associée de métaux précieux et de métaux de base. Des âges U–Pb d'environ 73–69 Ma pour le pluton de Capoose et les rhyolites grenatifères hypabyssales à extrusives dans la zone d'intérêt Capoose démontrent un âge Crétacé terminal pour la minéralisation et une source plutonique probable pour les fluides minéralisateurs. Un âge U–Pb d'environ 67 Ma pour un dyke felsique à minéralisation tardive et deux datations K–Ar (ca. 70 et 68 Ma) pour des roches volcaniques au faciès des cornéennes, datant du Jurassique, à la zone d'intérêt Blackwater–Davidson limitent l'âge de la minéralisation au Crétacé terminal. Un âge U–Pb d'environ 74 Ma pour un filon-couche de diorite à grains fins qui recoupe une importante veine d'or épithermale à la zone d'intérêt Tsacha donne un âge minimum pour la minéralisation de ce dépôt, probablement au Jurassique–Crétacé, et documente le magmatisme au Crétacé terminal. Des datations K–Ar de Crétacé terminal sont rapportées pour un écoulement d'andésite adjacent au gisement de Holy Cross, datant de l'Éocène (ca. 66 MA), situé à environ 35 km au nord de la chaîne Fawnie et pour une rhyolite du Groupe de Kasalka (ca. 68 Ma) affleurant près de la bordure ouest du plateau Nechako. Du magmatisme et de la minéralisation dans la chaîne Fawnie, au Crétacé terminal, représentent les dernières phases du magmatisme de la suite Bulkley et de la minéralisation de type porphyrique, qui a été concentrée le long de la bordure ouest du plateau Nechako il y a environ 88–70 Ma. On passe en revue la distribution des roches ignées d'arc au Crétacé terminal le long de la Cordillère nord-américaine et on discute des implications tectoniques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
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50. Geochronology of mid-Cretaceous to Eocene magmatism, Babine porphyry copper district, central British Columbia.
- Author
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MacIntyre, D G and Villeneuve, M E
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HISTORICAL geology ,GEOLOGICAL time scales ,MAGMATISM ,PORPHYRY ,IGNEOUS rocks - Abstract
New U/Pb and [sup 40] Ar/[sup 39] Ar isotopic dating in the Babine porphyry copper district of central British Columbia documents three distinct magmatic events at 107–104, 85–78, and 54–50 Ma. The earliest event involved emplacement of rhyolite domes into submarine volcanic rocks of the Rocky Ridge Formation. The rhyolite domes and related dacitic to basaltic volcanic rocks gave a U–Pb age of 107.9 ± 0.2 Ma and an [sup 40] Ar/[sup 39] Ar age of 104.8 ± 1.2 Ma. The rhyolites, which were previously mapped as Eocene, are reinterpreted to be part of a previously unrecognized mid-Cretaceous cauldron subsidence complex. The regionally extensive Late Cretaceous magmatic event is also recognized in the Babine district and is represented by [sup 40] Ar/[sup 39] Ar ages of 85.2 ± 2.8 and 78.3 ± 0.8 Ma on two Bulkley intrusions, one of which has associated porphyry copper mineralization. The final magmatic event is the most widespread and involved emplacement of the Babine intrusions and formation of numerous porphyry copper deposits including the Bell and Granisle past producers. Twenty-one new [sup 40] Ar/[sup 39] Ar isotopic ages for these intrusions and coeval andesites of the Newman Formation have a narrow range from 53.6 ± 0.9 to 49.9 ± 0.6 Ma, whereas previous K–Ar isotopic dating had a possible range of 15 Ma. The mid-Cretaceous, Late Cretaceous, and Eocene magmatic suites in the Babine district are interpreted to be part of a long-lived volcano-plutonic complex that was the site of periodic magmatism and porphyry copper mineralization over a 60 Ma time period. This complex may have evolved within a zone of extension (pull-apart basins) situated between dextral strike-slip faults that were active during periods of rapid oblique plate convergence.De nouvelles datations U–Pb et isotopiques [sup 40] Ar/[sup 39] Ar dans le district de cuivre porphyrique Babine, du centre de la Colombie-Britannique, documentent trois événements magmatiques distincts à 107–104 Ma, 85–78 Ma et 54–50 Ma. L'événement le plus précoce impliquait la mise en place de dômes de rhyolite dans les roches volcaniques sous-marines de la Formation de Rocky Ridge. Les dômes de rhyolite et les roches volcaniques apparentées dacitiques à basaltiques ont donné un âge U–Pb de 107,9 ± 0,2 Ma et un âge [sup 40] Ar/[sup 39] Ar de 104,8 ± 1,2 Ma. Les rhyolites, antérieurement cartographiées comme datant de l'Éocène, sont réinterprétées comme faisant partie d'un complexe de cuvettes d'effondrement auparavant non reconnues et qui dateraient du Crétacé moyen. Le magmatisme extensif régional du Crétacé tardif est aussi reconnu dans le district de Babine et il est représenté par des âges [sup 40] Ar/[sup 39] Ar de 85,2 ± 2,8 et 78,3 ± 0,8 Ma sur deux intrusions Bulkley, dont l'une présente une minéralisation associée de cuivre porphyrique. L'événement magmatique final est le plus répandu et il comprend la mise en place des intrusions Babine et la formation de nombreux gisements de cuivre porphyrique incluant les anciens gisements productifs de Bell et de Granisle. Vingt et un nouveaux âges [sup 40] Ar/[sup 39] Ar pour ces intrusions et des andésites contemporaines de la Formation Newman ont une plage étroite de 53,6 ± 0,9 à 49,9 ± 0,6 alors que des datations antérieures d'isotopes K–Ar avaient une plage de 15 Ma. Les suites magmatiques du Crétacé moyen, du Crétacé tardif et de l'Éocène dans le district de Babine sont interprétées comme faisant partie d'un complexe volcano-plutonique de longue durée où s'est produit du magmatisme périodique et de la minéralisation en cuivre porphyrique durant une période de 60 Ma. Ce complexe peut avoir évolué à l'intérieur d'une zone d'extension (basins d'extension) située entre des failles dextres à décrochement horizontal qui étaient actives durant les périodes de convergence rapide et oblique des plaques.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]
- Published
- 2001
- Full Text
- View/download PDF
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