bluuebunny/crossref_metadata_2025 huggingface dataset:
Metamorphism of high-grade pelites in the Brabant Lake area, eastern La Ronge Domain, northern Saskatchewan
Authors: Abbas-Hasanie Syed A. F. , Lewry John F. , Perkins Dexter
Published: April 2011

The Brabant Lake area mostly comprises Early Proterozoic clastic metasediments of the MacLean Lake belt, eastern La Ronge Domain, Reindeer Zone. The belt underwent upper amphibolite facies metamorphism, with sillimanite occurring in both psammitic and pelitic gneisses. Biotite + garnet + sillimanite + cordierite + quartz + K-feldspar + plagioclase parageneses suggest peak metamorphic pressure–temperature (P–T) conditions of 650–750 °C at 4–6 kbar (1 bar = 100 kPa) and [Formula: see text]. Both psammitic and pelitic gneisses underwent anatexis, which may have caused a reduction in water pressure. P–T conditions were also calculated by applying thermometry on the basis of garnet–biotite Fe–Mg exchange and barometry on the basis of garnet + plagioclase + sillimanite + quartz assemblages. The most precise garnet–biotite thermometer yielded temperatures of 608–758 °C (mean 690 °C). A more recent version, which incorporates the effects of minor components and nonideal mixing in both garnet and biotite, yielded a wider range of temperatures (565–826 °C), suggesting that imprecision in garnet–biotite thermometry may be due to disparate closing temperatures or disequilibrium. Application of several recent calibrations of the grossular + anorthite + sillimanite + quartz barometer produced a range of pressure estimates: three of these calibrations gave results compatible with documented mineral parageneses and experimental data, yielding 6.1 ± 0.5,6.1 ± 0.8, and 6.8 ± 0.9 kbar, respectively. Estimated mean pressures from another calibration are about 1–2 kbar higher. Peak metamorphic conditions at Brabant Lake are comparable with those experienced by metasediments of the Kisseynew Domain in Saskatchewan and Manitoba and other portions of the Reindeer Zone. Of 19 analyzed garnets from metapelites, 4 showed distinct chemical zonation. Garnet core growth appears coeval with syn-D2 peak metamorphic conditions; such cores yield the highest temperature estimates. Lower temperature estimates from garnet rims (range 610–660 °C, mean 630 °C) reflect retrogression under postpeak metamorphic conditions.
Timing of Pleistocene glacial events in New York State
Authors: Muller Ernest H. , Calkin Parker E.
Published: April 2011

This review of age data for the Pleistocene of New York identifies both strengths and weaknesses in the temporal framework relating the glacial chronology of the Great Lakes region to that of the middle Atlantic seaboard. The pre-Wisconsinan record involves saprolith and till in the Adirondack Mountains, marine clay on Long Island, multiple tills at Fernbank, Otto, and Gowanda, and major drainage derangement of the Allegheny River. Middle Wisconsinan ice spread into the Allegheny Plateau, damming high-level lakes in Cayuga Trough and southern Ontario. Long Island pollen data show late Middle Wisconsinan warming, the Plum Point Interstade. Glacially overridden organic matter at Rush Creek, Lord Hill, and St. Davids shows that this episode ended by 24 000 BP. Maximum Late Wisconsinan glaciation occurred during the Nissouri Stade, 21 750 – 18 570 BP. The concept of an Erie Interstade implies that ice recession, 15 000 – 16 000 BP, permitted lake drainage across New York. New York evidence allows this interpretation, but fails to establish the extent of ice withdrawal. Port Bruce drift incorporates Erie Interstade lake sediments. Radiocarbon data at Nichols Brook suggest that Valley Heads recession began by 14 000 BP. About 13 000 BP, the Port Huron Advance to the Hamburg Moraine dammed Lake Whittlesey. Subsequent glacial recession opened eastward drainage before readvance restored Lake Warren. By 12 000 BP, Lake Iroquois occupied the Ontario plain. Pollen data indicate that marine incursion of the St. Lawrence Valley occurred 500–1000 years later than suggested by shell dates.
Géochimie des horizons d'oxydes ferro-manganésifères noirs enrichis en or dans la latérite de Misséni, au Mali
Authors: Séa Frédéric , Trudel Pierre , Tanguay Marc G.
Published: April 2011

The laterite overlying the Misséni gold occurrence in Mali is characterized by the presence of remarkable black layers of ferro-manganiferous oxides. In an attempt to study the origin of the concentrations in these layers, 56 rock and soil samples were collected from three wells and from a borehole near the occurrence. The bedrock of the area is composed of Lower Proterozoic volcano-sedimentary formations, within which primary gold is associated with copper and iron sulphides disseminated in crushed and silicified zones in andesites and andesitic volcaniclastites. The general profile of the laterite at Misséni, from bottom to top is as follows: (i) saprolite (including the Fe–Mn oxides rich layers), (ii) ferruginous hardpan, (iii) ferruginous cuirasse, and (iv) eluvium. The mineralogical composition of the layers rich in Fe–Mn oxides is dominated by geothite, hematite, psilomelane, and quartz enveloped in a kaolinite matrix. There is a significant increase of the following elements in these layers: (i) trace elements: Au, Cu, Co, Ba, W, Pb, V, Be, As, Sb, Cs, Se, U, and Th; (ii) rare-earth elements: La, Ce, Sm, Yb, Eu, Lu, and Tb. The average gold content measured in these layers of black Fe–Mn oxides is 672 ppb. These gold concentrations are three times higher than the amount of gold found in the saprolite (233 ppb) surrounding these layers and six times superior to the gold content measured in the country rock (109 ppb) hosting the auriferous zone. The gold content of oxide grains derived from the black layers range from 0.25 to 7.7 ppm. The black layers of Fe–Mn oxides of Misséni are probably related to the remnants of an old phreatic surface, above which the oxides of Fe–Mn were deposited as a result of the prevailing oxidation conditions in this environment. The gold would have precipitated synchronously, by reduction from gold thiosulphate and its adsorption on the newly formed oxides. [Journal Translation]
Nd, Sr, and Pb isotopic evidence for contrasting origins of late Paleozoic volcanic rocks from the Slide Mountain and Cache Creek terranes, south-central British Columbia
Authors: Smith Alan D. , Lambert Richard StJ.
Published: April 2011

The Slide Mountain and Cache Creek terranes are two prominent oceanic sutures in the Canadian Cordillera. Petrological and isotopic variations between volcanic rocks in these terranes support earlier interpretations from stratigraphic evidence that the Slide Mountain terrane represents the remnant of a late Paleozoic basin situated marginal to western North America, whereas the Cache Creek terrane represents a remnant of a much larger, open-ocean basin. Slide Mountain terrane volcanic rocks, represented by Late Pennsylvanian basalts of the Fennell Formation, resemble normal mid-oceanic ridge basalts but possess an unusual kaersutite- or augite-dominated mineralogy. Their εNd(300 Ma) values of +7.7 to +10.2 are among the highest observed for Paleozoic basalts. The hydrous mineralogy can be reconciled with eruption on a spreading ridge in either a back-arc or marginal basin setting. The latter is preferred from Pb isotope compositions (206Pb/204Pb = 17.7–18.5, 207Pb/204Pb = 15.51–15.61, 208Pb/204Pb = 37.2–38.8), which suggest exchange with high Th/U continental-derived sediment during hydrothermal alteration. Volcanic rocks, probably middle Mississippian, in the Bonaparte subterrane of the Cache Creek terrane include picrites and basalts belonging to a within-plate tholeiite suite. The intraplate suite broadly resembles Hawaiian basalts in major and trace element composition. However, moderate positive εNd values (εNd(340 Ma) +4.2 to +5.6) and a transition toward DUPAL signatures in Pb isotopic composition (206Pb/204Pb = 18.1–19.1, 207Pb/204Pb = 15.54–15.61, 208Pb/204Pb = 37.8–38.6) are features more similar to volcanic rocks from modern South Pacific ocean islands. Basaltic andesite and andesitic tuffs, also found in the Bonaparte subterrane, are tentatively correlated with Late Triassic to Early Jurassic low-K tholeiitic volcanic rocks of the Nicola Group on the Quesnel terrane.
Processus d'altération thermique, physico-chimique et biologique de constituants organiques et genèse d'une minéralisation sulfurée : le gîte Zn-Pb de La Florida (Cantabria, Espagne)
Authors: Hu M A , Disnar J R , Barbanson L , Suarez-Ruiz I
Published: April 2011

The La Florida lead-zinc deposit (Cantabria, Spain), which is hosted by Urgonian carbonates, is located on the border of the Basco-cantabric Lower Cretaceous basin. The stratiform orebody, which is composed of sphalerite, galena, and barite in iron-dolostones, occurs in an envelope of dolostone. Organic matter studies have been carried out on samples from this deposit to understand its genesis and later evolution. The results of this work reveal the immatury of the autochthonous organic matter despite a slight paleothermal anomaly centred on the deposit. Various alteration processes have affected the hydrocarbons associated with autochthonous organic matter and (or) allochthonous bitumens, namely geochromatographic fractionation, water-washing, and biodegradation. Together with previous geological work, the results of this study are consistent with epigenetic and (or) diagenetic emplacement of the mineralization. The proposed genetic scheme involves hydrothermal fluids that would have acquired at least some of their characteristics during their upward migration through the Mesozoic cover. These solutions probably brought in the metals, the sulphates, and the organics all necessary for in situ hydrogen sulphide production and ore genesis. Sulphate reduction probably proceeded mostly at the expense of allochthonous organics by bacteria introduced by meteoric water infiltrations.
Les dépôts coquilliers (faluns) holocènes de Baie-Comeau, Côte-Nord de l'estuaire du Saint-Laurent, Québec
Authors: Bernatchez Pascal , Dubois Jean-Marie M , Dionne Jean-Claude
Published: April 2011

Extensive shell beds were found in the valley of Rivière aux Anglais, near Baie-Comeau, along the North Shore of lower St. Lawrence River. Those particular accumulations, more or less well stratified and ranging from 2 to 15 m thick, represent the top parts of unconsolidated formations of the Goldthwait Sea between 10.4 and 9.6 ka BP. About 10 mounds have been discovered up to now. Their sizes vary, but reach 50 × 103 m2. Most overlie fine stratified sediments, such as fine sand, silt, and clay. They consist mainly of shell remains, which sometimes represent up to 90-95% of the volume. We can find various species of cirripeds (3), gastropods (7), brachiopods (1), echinoderms (1), and mostly pelecypods (11) including a large percentage of unbroken shells. Stratigraphic evidence suggests that these are natural formations (faluns) formed in a marine environment by sedimentation inside a seashore of ria type, where the sea currents and waves played a prominant role in the concentration of shell remains. The quantity of shells implies an environment of strong primary productivity, but also particular climatic conditions (frost) leading to a high number of deaths.
Timing and kinematics of post-Timiskaming deformation within the Larder Lake - Cadillac deformation zone, southwest Abitibi greenstone belt, Ontario, Canada
Authors: Wilkinson Lori , Cruden Alexander R , Krogh Thomas E
Published: April 2011

The Larder Lake - Cadillac deformation zone is one of several anastomosing zones of high strain within the Abitibi greenstone belt. In the Kirkland Lake area, Ontario, the Larder Lake - Cadillac deformation zone is characterized by extensive carbonate and chlorite alteration, strong south-dipping foliations, and steep lineations. These features formed during two ductile deformation increments, D2 and D3, that occurred after deposition of Timiskaming assemblage sediments. D2 strain accumulation and greenschist facies metamorphism and alteration were localized within the deformation zone, facilitated by channelling of hydrothermal fluids within a preexisting structure, possibly formed during early D1 terrane accretion. During D2 north-south shortening, east-west-trending sectors of the deformation zone accumulated bulk coaxial strains, while southeast- and northeast-trending sectors experienced, respectively, dextral and sinistral transpressive deformations. Preservation of Timiskaming assemblage sediments in the footwall of the deformation zone indicates a component of south-over-north (reverse) displacement that is not recorded by D2 fabrics. Northwest-southeast D3 compression resulted in the formation of a regional, northeast-striking cleavage formed under regional greenschist facies conditions, and local dextral reactivation of suitably oriented sections of the Larder Lake - Cadillac deformation zone. The Murdoch Creek and Lebel stocks abut the Larder Lake - Cadillac deformation zone. Their internal structure and emplacement are interpreted to be a consequence of D2 north-south shortening. Magmatic zircon and titanite in the Murdoch Creek and Lebel stocks yield U-Pb geochronology ages of 2672 ± 2 and 2673 ± 2 Ma, providing a maximum age for D2 deformation. Hydrothermal titantite associated with S3 foliation in the Murdoch Creek stock gives an U-Pb age of 2665 ± 4 Ma, the maximum age of D3 deformation. Pluton emplacement, deformation, and coincident metamorphism occurred over a span of 1 Ma (from 2670 to 2669 Ma) to over 14 Ma (from 2675 to 2661 Ma), during a regime of north-south, followed by northwest-southeast, regional shortening.
A review of high-resolution seismic profiling across the Sudbury, Selbaie, Noranda, and Matagami mining camps
Authors: Adam Erick , Perron G , Milkereit B , Wu Jianjun , Calvert A J , Salisbury M , Verpaelst Pierre , Dion Denis-Jacques
Published: April 2011

Lithoprobe high-resolution seismic surveys have provided the first systematic images of the deep stratigraphy in four major Canadian mining camps (Noranda, Matagami, Sudbury, and Selbaie). Systematic compressional wave velocity and density measurements in deep boreholes have established that lithological contacts were the main impedance contrast imaged, although reflections from faults and deformation zones have also been observed. The strongest reflections are attributed to mafic intrusions and some sulphides and oxides. Integrating seismic, physical rock property measurements, and geological data has resulted in the revision of several geological models with direct impact on local strategies for deep mineral exploration. Mining companies have shown an interest in seismic reflection methods and this has led to several follow-up studies. The application of seismic methods to the direct detection of massive sulphides, based on physical rock property measurements, has been studied through two-dimensional and three-dimensional (3D) seismic imaging and vertical seismic profiling technologies. The challenge will now be to optimize 3D seismic imaging for mineral exploration and to improve seismic data processing by enhancing the seismic response from deep, lenticular orebodies.
Geochemical and radiogenic isotope (Sr-Nd) characteristics of Paleoproterozoic anorthositic and granitoid rocks in the Umiakoviarusek Lake region, Labrador, Canada.
Authors: Piercey Stephen J , Wilton Derek HC
Published: April 2011

Recent work in the north-central Labrador has identified Paleoproterozoic anorthositic and granitoid rocks that are spatially associated with, yet temporally distinct from, younger Mesoproterozoic intrusions of the Nain Plutonic Suite. The Umiakoviarusek Lake (UL) region of Labrador contains several of these Paleoproterozoic intrusions and provides an opportunity to study their geochemical and radiogenic isotope (Sr-Nd) characteristics. Geochemically, the anorthositic and granitoid rocks have features consistent with contemporary anorthositic and granitoid rocks from other anorthosite-mangerite-charnockite-granite complexes. The anorthositic rocks contain elevated contents of Al2O3, CaO, Sr, and Eu with low Ba, Rb, K, Zr, total rare earth elements (REE), and light REE. The granitoid rocks, on the other hand, contain lower concentrations of these elements along with elevated SiO2 and K2O. Isotopic data at 2050 Ma for the anorthositic rocks (ISr = 0.7048-0.7082; εNd = -4.1 to -15.9) and granitoid rocks (ISr = 0.7036-0.7094, εNd = -5.1 to -9.7) are consistent with variable crustal and mantle contributions to their genesis. The relatively unradiogenic Sr and slightly evolved Nd isotopic data from the UL granitoid rocks is consistent with a significant juvenile mantle component, possibly derived from an underplating mantle plume; this component may also be present in the anorthositic rocks. The Nd and Sr isotopic data are also consistent with crustal contamination from Archean source materials; however, based on the existing isotopic database for the Nain Province gneisses, it is not possible to delineate a specific gneiss component. Furthermore, it is also quite possible that an Archean source, unlike any described at present, was a crustal source component in the UL intrusive rocks.
Archean crustal evolution of the northwestern Superior craton margin: U-Pb zircon results from the Split Lake Block
Authors: Böhm Christian O , Heaman Larry M , Corkery M Timothy
Published: April 2011

The Split Lake Block forms a partly retrogressed, granulite-grade basement segment located at the northwestern margin of the Superior Province in Manitoba. Unlike other segments along the craton margin, the effects of Proterozoic tectonism are relatively minor in the Split Lake Block, making it amenable to establishing firm temporal constraints for the Archean magmatic and metamorphic history of the northwestern Superior Province margin. Consequently, samples from the main lithological units within the Split Lake Block were selected for precise single-grain U-Pb zircon geochronology. Heterogeneous zircon populations isolated from representative enderbite, tonalite, and granodiorite samples reveal a complex growth history with pre-2.8 Ga protolith ages (e.g., 2841 ± 2 Ma tonalite), possibly as old as 3.35 Ga as indicated in a granodiorite sample. The youngest Archean granitic magmatism identified in the eastern Split Lake Block is represented by the 2708 ± 3 Ma Gull Lake granite. A U-Pb zircon age of 2695+4-1 Ma obtained for leucosome in mafic granulite is interpreted to reflect the timing of granulite-grade metamorphism in the Split Lake Block, supported by polyphase zircon growth and (or) lead loss at ca. 2.7 Ga in the enderbite sample. A younger phase of metamorphic zircon growth at ca. 2.62 Ga is documented in the tonalite and granodiorite zircon populations. The 2.70-2.71 Ga crust formation, the occurrence of ca. 2695 Ma high-grade metamorphism, and broadly contemporaneous Paleoproterozoic mafic dykes in both the Split Lake Block and Pikwitonei Granulite Domain imply a common evolution of these high-grade terrains along the northwestern Superior craton margin since the late Archean.
Evolution of Cheekye fan, Squamish, British Columbia: Holocene sedimentation and implications for hazard assessment
Authors: Friele Pierre A , Ekes C , Hickin E J
Published: April 2011

Cheekye fan, a large (~25 km2) fan located at the head of Howe Sound, southwestern British Columbia, has its origins in the collapse of the western flank of Mount Garibaldi onto a waning Late Pleistocene glacier, followed by post-glacial redistribution of colluvial-glacial sediments. Reconstruction of internal fan architecture allowed characterization of the rapid decline in sediment delivery to the lower fan through the paraglacial period, a result holding important implications for hazard assessment. A ground penetrating radar profile on lower Cheekye fan has reflectors with a steep (25°), westerly dip lying between 48 and 26 m above sea level, which are interpreted as foreset beds. Radiocarbon ages from marine deltaic deposits at the head of Howe Sound indicate that the sea stood at about 45 m above sea level at 10 200 BP. Together, the data indicate that the head of Howe Sound was deglaciated by 10 200 BP, that the fan had prograded 2.5 km into the fjord by this time, and continued to prograde as relative sea level fell. Reflectors at -10 m above sea level with a steep southerly dip along the southern edge of the lower fan, and radiocarbon ages in this vicinity, indicate it had reached close to its modern extent by 8000-9000 BP. Calculation of the volume of sediment stored in the lower fan indicates that at least 90% of the material was deposited before 6000 BP. This indicates that the Cheekye fan is largely a relict feature, putting its large size into context for future hazard assessments.
Late Laramide dolomite recrystallization of the Husky Rainbow "A" hydrocarbon Devonian reservoir, northwestern Alberta, Canada: paleomagnetic and geochemical evidence
Authors: Lewchuk Michael T , Al-Aasm Ihsan S , Symons David TA , Gillen Kevin P
Published: April 2011

The Rainbow Field is in reefal carbonates of the Middle Devonian Keg River Formation in the Western Canada Sedimentary Basin. Alternating field and thermal step demagnetization was done on specimens from unoriented core from a vertical, an inclined, and a horizontal well core in the dolomite reservoir. Although they had no viscous remanent magnetization component to use for orientation, most specimens had a well-defined characteristic remanent magnetization (ChRM) that resides in single to pseudosingle domain magnetite. By rotating the mean ChRM direction around its core axis, a small circle can be generated for each core and the small circles intersect in the true ChRM direction of D = 168°, I = -73.5o (α95 = 5.8°, k = 32.2). Its paleopole of 164°E, 83°N (A95 = 10°) defines a Tertiary age with one sigma limits of Middle Eocene to Middle Miocene age. Petrographic examination defines four generations of dolomite. Matrix dolomite has 60-100 µm diameter crystals that were later recrystallized to 200-400 µm. Dolomite cements are represented by vug-filling coarse dolomite (100-200 µm) and saddle dolomite (1000 µm). All four generations of dolomite give similar δ18O values of -10.7 to -16.5 (Peedee Belemnite, PDB), δ13C values of +0.7 to +3.2 (PDB), and Sr isotopic ratios of 0.70826 to 0.70846 that do not match the expected Middle Devonian carbonate or seawater values. We interpret these data to indicate that mixed pre-Laramide basinal fluids, heated by burial during the Laramide Orogeny, were present during late Laramide time when the dolomites were recrystallized and (or) precipitated prior to petroleum migration and accumulation in the Rainbow "A" reservoir. Thus the combined use of paleomagnetism, geochemistry, and petrography has been proven to be a useful technique to date and identify dolomitization events and pathways for the migration of hydrocarbons.
Large-scale effects of subglacial meltwater flow in the southern Slave Province, Northwest Territories, Canada
Authors: Rampton V N
Published: April 2011

Broad corridors in the southern Slave Province of the Northwest Territories are marked by meltwater-scoured bedrock, irregular and transverse gravel ridges, gravel bars, crag and tail features (tails formed of gravel), drumlins, boulder lags, potholes, plunge pools, meltwater-sculpted slopes (in some cases defining till plateaus), and eskers. Most of the above features can either be attributed to the subglacial erosion of till by high-velocity, turbulent meltwater under high pressures and (or) meltwater transport and deposition of the eroded material. Potholes, plunge pools, and meltwater-sculpted slopes developed in unconsolidated deposits have received little attention in the literature, although they are the equivalent of similar features in bedrock that have had their origin attributed to subglacial meltwater erosion. In the case of inverted plunge pools, eroded materials, including boulders, have been transported upwards by meltwater some tens of metres during their formation. Features and deposits owing their origin to subglacial meltwater can lead to complex dispersal patterns of minerals and metals contained within both till and glaciofluvial deposits.
Population study of electrophoretic polymorphisms of red cell enzymes and plasma proteins in Caucasian Canadians
Authors: Philipps Sylvia , Giblett Eloise R. , Anderson Jeanne E. , Lewis Marion , Kaita Hiroko
Published: April 2011

Blood samples from a random series of Canadian Caucasians were phenotyped for 28 red cell enzyme systems and eight plasma protein systems. Polymorphism was found in 17 and rare variants in 11 of the systems. Allele frequencies are presented for these; distribution of phenotypes is in accordance with the Hardy–Weinberg equilibrium theory. In a complementary study of families there was no evidence of de novo mutation in any of the 36 systems and they allowed a minimum estimate of the frequency of null alleles in the ADA, C2, and GPT systems.

Key words: polymorphism, red cell enzyme, plasma protein, phenotype, allele frequency, population.
A DNA cytophotometric and chromosome banding study in Hedera helix (Araliaceae), with reference to differential DNA replication associated with juvenile–adult phase change
Authors: König C. , Ebert I. , Greilhuber J.
Published: April 2011

The present DNA cytophotometric and chromosome banding comparison of the juvenile and the adult developmental phase in the common ivy, Hedera helix, was undertaken as an attempt to verify or refute the asserted phase-correlated differential DNA replication in this plant. No statistically significant differences between the two developmental phases were found in genome size (as determined from mitotic nuclei), nuclear DNA content in resting meristems and somatic leaf tissues, and content of constitutive heterochromatin as measured from C-banded metaphase plates. There is no evidence for differential DNA replication in Hedera helix.

Key words: Hedera helix, differential DNA replication, morphogenesis, genome size, chromosome structure.
Chromosome organization in meiosis revealed by light microscope analysis of silver-stained cores
Authors: Rufas J. S. , Gimenez-Abian J. , Suja J. A. , Vega C. Garcia De La
Published: April 2011

Three species of grasshoppers have been analyzed by means of a modified silver impregnation technique that reveals the presence of a chromatid core that identifies chiasmata at first meiotic metaphase. In terms of the behaviour of the chromatid core most of the configurations observed at diplotene with orcein are easily recognized in metaphase I silver-stained bivalents. Some "hidden" configurations, as well as simple chromatin associations, that do not appear to represent chiasmata have also been detected. The disposition and behaviour of the chromatid cores in metaphase I and anaphase I provide grounds to support a reorganization of half-bivalents between first and second division.

Key words: chromatid core, meiotic chromosome organization, chiasma formation, insect cytogenetics.
Progenies of Thinopyrum elongatum × Agropyron mongolicum
Authors: Wang Richard R-C.
Published: April 2011

With the aid of embryo rescue, both a monoploid and several hybrids were obtained from the cross Thinopyrum elongatum × Agropyron mongolicum. The monoploid was a result of gradual and eventually complete elimination of A. mongolicum chromosomes in the hybrid. About 95% of the root-tip cells, and nearly all of the pollen mother cells, had only the seven chromosomes of the Je genome of the maternal parent. Very little autosyndesis occurred between chromosomes within the Je genome. Extensive chromosome pairings were observed in one headed hybrid, averaging 6.42 I + 2.53 rod II + 0.85 ring II + 0.25 III + 0.02 IV at metaphase I in pollen mother cells, which revealed a high degree of chromosome homology between the two genomes and thus justifying the close phylogenetic relationship between the two species. All plants died from hybrid necrosis, some as seedlings and some after heading. The Je and P genomes in the accessions used in this study carry complementary genes for hybrid necrosis.

Key words: hybrid (intergeneric), haploid, genome, chromosome elimination, meiosis.
Isolation and mapping of DNA probes within the linkage group I gene cluster of Caenorhabditis elegans
Authors: Starr T. , Howell A. M. , McDowall J. , Peters K. , Rose A. M.
Published: April 2011

We have isolated probes for DNA polymorphisms across the linkage group I gene cluster in Caenorhabditis elegans, using Tc1-linkage selection. The probes detect strain polymorphism between the wild-type strains of var. Bristol and var. Bergerac. As a result of mapping the sites hP4, hP5, hP6, hP7, hP9, and sP1, more than 1000 kilobases (kb) of cloned cosmid DNA has been positioned on the genetic map. We found there is more DNA per map unit in the center of the gene cluster than expected on the basis of the genomic average. Furthermore, the amount is not constant across the entire region but reaches a peak in the hP9 unc-13 interval. To find the coding regions, we examined DNA cross-homology between two species, Caenorhabditis elegans and Caenorhabditis briggsae. Approximately one-third of the DNA in the hP5 hP9 interval was examined for coding regions and 21 sequences were identified within 318 kb of DNA.Key words: Caenorhabditis elegans, physical map, DNA polymorphisms, genetic mapping, Caenorhabditis briggsae.
Genetic structure and identification of Populus deltoides clones based on allozymes
Authors: Rajora Om P.
Published: April 2011

The allelic constitution of 30 Populus deltoides Marsh, clones selected in Canada and United States was determined for 37 allozyme loci coding for 12 enzyme systems in root tips. The enzymes were assayed by horizontal starch gel electrophoresis. One common allele was found at each locus in all clones. The interclonal allozyme variability was controlled by 12 loci. The average proportion of heterozygous loci per clone was 4.7%. There were 23 unique multilocus genotypes among 30 clones. On average, unique genotypes differed from each other at 4.33 loci. Principal-component analysis of clonal genotypes at 12 polymorphic loci indicated 8 loci to be the most differentiating for the clones. The first three principal components accounted for 47.6% of the total variation in 12 polymorphic loci. The ordination and grouping of the clones on principal components 1, 2, and 3 portrayed clonal relationships. Clones from the same small nautral population at Cherry Beach, Ont., and five clones of P. deltoides var. occidentalis were in the same group. There was no separation of clones of two varieties, P. deltoides var. deltoides and P. deltoides var. occidentalis. These results and their usefulness were discussed with reference to identification, certification, registration, and relationships of clones.Key words: Populus deltoides Marsh., allozymes, multilocus genotypes, clone characterization, clonal relationships, poplars.
Persistence of a scour hole on the East Channel of the Mackenzie Delta, N.W.T.
Authors: Fassnacht Steven R , Conly F Malcolm
Published: April 2011

Anomalies in the bathymetry of river channels are of great practical concern for designing sub-bed pipeline crossings. Of particular interest is the long-term stability of deep holes. Bathymetric evidence indicates that one unusually deep hole in the East Channel of the Mackenzie River, referred to as a scour hole, has existed as early as 1956. Detailed hydraulic and morphologic data were first collected in 1985, and again in 1992 to assess the spatial and temporal stability of the feature. Even with a record flood on the Mackenzie River in 1988, the hole, with a maximum depth approaching 30 m, was vertically stable over the 7-year period. However, lateral erosion and sedimentation have resulted in a shift in the horizontal position of the scour hole, with a maximum horizontal erosion of approximately 2 m/a. The average rate of lateral outward movement was observed to be 0.8 m/a.Key words: Mackenzie Delta, rivers, fluvial sediment, channel stability, scour, scour hole.
Sprayed fibre-reinforced polymers for repairs
Authors: Banthia N , Boyd A J
Published: April 2011

The use of fibre-reinforced polymers for repair and retrofit is growing at an unprecedented rate. This technique has been used for strengthening and rehabilitation of columns, beams, masonry, joints, etc. and has also found significant suitability for seismic applications. All research to date has focused, however, on wraps and jackets with continuous, unidirectional fibres. Within the auspices of Network of Centers of Excellence on Intelligent Sensing for Innovative Structures (ISIS) program, an entirely new method of fibre reinforced polymer coating is being developed. In this method, the composite with short, randomly distributed fibres is sprayed on the surface of concrete to be repaired. Composite gets pneumatically compacted on the application surface and develops a strong bond with concrete during the hardening process. In this paper, the effectiveness of the spray technique is compared with wraps carrying continuous fibres when applied to concrete cylinders under compression. To assess size effects, a companion test series involving larger cylinders was carried out. It was found that sprayed composites with randomly distributed short fibres performed equally well as or even better than wraps with continuous fibres. Within the continuous fibre wraps, those with a 0-90° fibre orientation are far more effective than those with a ±45° orientation.Key words: concrete, repair, glass fibre, polymer matrix, spray, wraps, deformability, size effects.
Design relations for predicting surface-ice clearing capacity of open channels
Authors: Morin I , Townsend R D , Morse B
Published: April 2011

Numerical simulations are performed to evaluate the impact of various hydraulic and environmental parameters on the ice clearing capacity of a Lac St-Pierre navigation channel. The Lagrangian particle-dynamics (Pdyn) model is used to simulate a wide range of "operating" conditions that are representative of conditions observed on Lac St-Pierre. Simple relationships are developed that express both ice velocity and flux as functions of the geometry of the channel (width and plan-form shape) and ambient conditions (ice concentration, thickness, water current, wind magnitude and direction). These relationships reflect the importance of wind characteristics and areal ice concentration in regard to predicting both surface ice velocities and flux.Key words: ice clearing, channel geometry, ambient conditions.
Modelling in situ shear strength testing of asphalt concrete pavements using the finite element method
Authors: Bekheet Wael , Hassan Yasser , El Halim AO Abd
Published: April 2011

Rutting is one of the well-recognized road surface distresses in asphalt concrete pavements that can affect the pavement service life and traffic safety. Previous studies have shown that the shear strength of asphalt concrete pavements is a fundamental property in resisting rutting. Laboratory investigation has shown that improving the shear strength of the asphalt concrete mix can reduce surface rutting by more than 30%, and the SUPERPAVE mix design method has acknowledged the importance of the shear resistance of asphalt mixes as a fundamental property in resisting deformation of the pavement. An in situ shear strength testing facility was developed at Carleton University, and a more advanced version of this facility is currently under development in cooperation with the Transportation Research Board and the Ontario Ministry of Transportation. In using this facility, a circular area of the pavement surface is forced to rotate about a normal axis by applying a torque on a circular plate bonded to the surface. The pavement shear strength is then related to the maximum torque. This problem has been solved mathematically in the literature for a linear, homogeneous, and isotropic material. However, the models for other material properties are mathematically complicated and are not applicable to all cases of material properties. Therefore, developing a model that can accurately analyze the behaviour of asphalt concrete pavements during the in situ shear test has proven pivotal. This paper presents the development of a three-dimensional finite element model that can simulate the forces applied while measuring the shear strength of the asphalt concrete pavement. A comparison between the model results and those obtained from available analytical models and field measurements proved the accuracy of the developed model.Key words: shear strength, in situ testing, finite element, asphalt, pavement, modelling.
Prédiction des résistances du ciment au laitier durcissant sous une temperature variable
Authors: Abdelkader Bougara , Karim Ezziane , Abdelkader Kadri
Published: April 2011

The prediction of concrete strength has become a major concern that is forcing the construction industry to look closely at determining the appropriate time when to strip the form work or to apply prestress forces to new concrete. Normal concrete has different constitutions and can be subjected to different curing methods depending on the means available. Its characteristics are defined by the presence of mineral additives used to improve its efficiency. This has led us to establish a work plan to predict the strength of slag concrete, tested at different temperatures, from the data obtained from some control specimens of normal concrete, made only from clinker and subjected to a constant temperature of 20°C. The slag material was obtained from El-Hadjar (Algeria).Key words: slag, activation, temperature, finesse, thermal treatment, prediction, equivalent time, mortar, compression, cement, additives.
Sizing of centralized leaf and yard waste composting facilities
Authors: Timms C E , Baetz B W
Published: April 2011

Many communities are facing serious solid waste disposal problems and considerable efforts are being made to reduce the quantities of municipal solid waste requiring disposal. Centralized composting of leaf and yard materials is gaining widespread popularity across North America in an attempt to divert these materials from landfill and process them into a valuable organic soil amendment for agricultural and horticultural purposes. To ensure the success of new centralized composting facilities, they must be adequately sized so that the incoming organic material can be suitably accommodated. This note presents a structured methodology for the sizing of centralized window composting facilities for leaf and yard materials, with land area requirements being determined for receiving, preprocessing, processing, and finishing operations. This approach may prove to be a useful tool to municipalities in the preliminary design of their centralized leaf and yard waste composting facilities.Key words: composting, municipal solid waste management, facility sizing.
Local buckling of thin-walled fibre composite beams under transverse loading
Authors: Kabir Mohammad Z , Sherbourne Archibald N
Published: April 2011

Plate structures are often subjected to differential compression due to nonuniform bending during their service life. In practice, most beams are subjected to transverse loads that create moment gradient; the resulting loading system for such beams is a combination of longitudinal stress gradient with associated shearing and transverse stresses. This paper presents a theoretical view of elastic local instability of anisotropic composite beams which are treated as assemblies of symmetric angle-ply composite plates buckling under nonlinear varying, uniaxial compressive forces. Uniformly distributed load and central concentrated load are two common loading systems acting on simply supported, wide-flange I-section beams. The Galerkin method is applied to the resulting plate equilibrium equations. The present study shows that the buckling load obtained from the proposed approach for composite flanges is greater than that obtained by existing solutions. Results also show that for beams subjected to the uniformly distributed load loading system, local buckling may be initiated in the web, especially for short-span deep beams. However, under the central concentrated load loading system, the compressive flange limits buckling strength.Key words: local buckling, stress gradient, fibre composite, pultruded beam.
Earthquake amplification factors for self-supporting telecommunication towers
Authors: Khedr Mohamed , McClure Ghyslaine
Published: April 2011

In the absence of specific guidelines for the seismic analysis of self-supporting telecommunication towers, designers may be tempted to apply building-code approaches to these structures. However, these towers respond to earthquakes in a different fashion than shear buildings. In this study, earthquake amplification factors for the base shear and the total vertical reaction of self-supporting latticed telecommunication towers are suggested based on modal superposition analysis performed on 10 existing towers, each being subjected to a set of strong-motion accelerograms acting in the horizontal and the vertical directions separately. Results are presented in detail for two of the towers studied, with heights of 66 and 121 m, respectively. Simple regression analyses are performed on the results from which the base shear and vertical reaction amplification factors are found. These factors are presented as functions of the tower's largest flexural period or largest axial period of vibration as appropriate, and can be used by designers to estimate the expected level of dynamic forces developed in self-supporting telecommunication towers due to an earthquake.Key words: dynamic analysis, lattice towers, base shear, vertical reaction.
Uncertainty analysis of ocean outfalls
Authors: Mukhtasor  , Sharp James J , Lye Leonard M
Published: April 2011

Variability and uncertainty are inherent in an ocean outfall system and will cause variation in estimated initial dilution and bacterial concentration at areas of interest near the discharge. Uncertainty analysis is therefore useful in evaluating the likely performance of the outfall and in determining if it will comply with relevant government regulations. This paper identifies the uncertainty in outfall design parameters for an outfall involving a single, horizontal, round buoyant jet discharging into an unstratified seawater environment. A case study based on data from the Spaniard's Bay outfall in Newfoundland, and using a Monte Carlo simulation, is presented and compared with some, limited, site data that are available. It is shown that the analysis adequately describes the probabilistic nature of the initial dilution and bacterial concentration and that it would be useful for practical design purposes.Key words: bacterial pollution, buoyant jet, initial dilution, Monte Carlo simulations, probabilistic design, sewage discharge, ocean outfalls, uncertainty analysis, water quality standard.
Effect of support conditions on seismic response of cable-stayed bridges
Authors: Tuladhar Raju , Dilger Walter H
Published: April 2011

The seismic response of a cable-stayed bridge is the result of the interaction between the input earthquake characteristics and the bridge properties like mass, stiffness, and support conditions. The support type used for the deck at the towers of cable-stayed bridges is one of the important parameters that greatly influences the seismic response of the bridge. This is demonstrated in the present paper by study of the change in modal characteristics and seismic response of two cable-stayed bridges for different types of the support conditions. The first bridge has concrete towers and a steel deck with a 371 m main span, and the second bridge also has concrete towers, but a composite deck with a 465 m main span. The study shows that elastic supports for the deck at the towers give very low deck displacements and deck bending moments compared to pinned or fixed connections. Roller supports produce low tower base shear and base moment but not necessarily a low response for the bridge as a whole. Roller supports also cause the bridge to have very low first longitudinal direction mode frequency; this indicates that the bridge is very flexible in the longitudinal direction. A study of the effect of variation of the longitudinal stiffness of the elastic deck supports shows that it strongly influences the first few longitudinal direction modes, but not the symmetric or higher modes. The study also shows that the seismic response of the bridge is highly influenced by the variation of the support stiffness for some earthquakes like 1940 El Centro earthquake, but to a lesser degree for others. Wave propagation effects were also studied for different support conditions of the bridge. It is observed that the seismic response shows a higher degree of variation with the changing wave velocities when the bridge deck has pinned or fixed supports, and that the change in the bridge response with the wave velocities is not very pronounced when the bridge deck has elastic or roller supports. For the first bridge, the critical responses were observed at very low wave velocities, and for the second bridge, the uniform motion case caused the critical response of the bridge at many locations.Key words: cable-stayed bridges, support conditions, seismic response, wave propagations.
Seasonal variation in material properties of a flexible pavement
Authors: Watson D K , Rajapakse RKND
Published: April 2011

Seasonal variation of temperature and moisture causes considerable changes in the load-carrying capacity of pavements in geographical areas subjected to extreme freeze/thaw conditions. The Seasonal Monitoring Program (SMP) of the Long Term Pavement Performance (LTPP) study of the Federal Highway Administration (FHWA) monitors seasonal variations in Falling Weight Deflectometer (FWD) deflections, air temperature, rainfall, soil temperature, moisture content, and soil electrical resistance at numerous sites across North America. This study relates changes in pavement load carrying capacity represented by the pavement layer resilient moduli to selected environmental factors for a test pavement site in southwestern Manitoba. The significant environmental parameters causing seasonal variation in pavement layer resilient moduli are identified as the surface temperature for the asphalt layer and the thawing index for base and subgrade layers. The resilient moduli of various pavement layers show a substantial decrease in magnitude with increasing values of respective environmental parameter. The present model can be used for preliminary verification of empirical pavement design and rehabilitation practices currently in use to account for seasonal variations. Key words: asphalt, backcalculation, falling weight deflectometer, freezing, pavements, moisture, resilient moduli, seasonal variation, thawing, temperature.