bluuebunny/crossref_metadata_2025 huggingface dataset:
Submarine flow tills at Victoria, British Columbia
Authors: Hicock Stephen R. , Dreimanis Aleksis , Broster Bruce E.
Published: April 2011

Sea cliffs at Victoria expose submarine flow tills within an ice-contact complex of flow till – outwash proglacial cones interbedded with dinoflagellate-bearing glaciomarine fine sediments. Glacial debris flow lobes (mainly flow tills) were formed by supraglacially, englacially, and basally transported sediment slumping off an ice margin grounded in the Strait of Juan de Fuca. The structures and textures reveal that lobes formed by a conveyor mechanism. In some lobes a double sorting phenomenon apparently developed involving an outer, winnowed, layer of pseudo-plastic flow around an inner core of till that was sorted by dewatering and expulsion of fines outward from the centre during flow. Structures and fabric data indicate lobe travel was gravitationally controlled down cone flanks and independent of ice movement.A depositional model for the complex proposes the ice margin produced a proglacial apron of interdigitating cones, which accumulated on the sea floor. Sediment facies variations were probably controlled by shifts in cone development along the margin: cones formed where glacial and glaciofluvial debris discharged from the ice into the sea and glaciomarine deposits accumulated from glacial flour suspended in the seawater between the cones.Although this is the first reported example of submarine flow tills, casual observations elsewhere suggest that they are common in coastal areas.
The walking speed of dinosaurs from the Peace River Canyon, British Columbia, Canada
Authors: Kool Richard
Published: April 2011

The walking speed of seven dinosaur ichnospecies from the Lower Cretaceous Peace River Canyon, British Columbia, Canada, have been determined. The speeds range from approximately 1 to 3 m s−1 (4–10 km h−1).
Geochemical, mineralogical, and isotopic data relating to the origin and tectonic setting of the Rossland volcanic rocks, southern British Columbia
Authors: Beddoe-Stephens B. , Lambert R. St J.
Published: April 2011

Bulk-rock and mineral chemical and isotopic analyses of Rossland volcanic rocks are used to infer the nature of the magma extruded in the Nelson–Rossland area of southern British Columbia during the Early Jurassic. Metamorphism of the volcanic rocks to subgreenschist and greenschist facies precludes use of mobile major and trace elements (e.g., Na, K, and Rb) as petrogenetic indicators. Data on immobile elements (Ti, Zr, and Y) and pyroxene compositions indicate that the volcanic rocks formed in a destructive-margin plate tectonic environment. Present-day 87Sr/86Sr ratios range from 0.70372 to 0.70480 but do not define an isochron. Corrected to Jurassic time, the initial ratios range from 0.70328 to 0.70404. Whole-rock δO18 values range from 7.9 to 11.6%, correlating inversely with metamorphic grade. Clinopyroxene δO18 of 4.8–6.5 is comparable with fresh clinopyroxenes from mafic rocks of mantle origin. In view of the preponderance of basaltic rather than andesitic rock types, and because of the nature of the lithologies within the volcanic rocks and associated sediments, an island-arc setting is indicated. The appearance of primary amphibole in basaltic members of the Rossland suite, and the occurrence of ankaramitic rocks, are thought to indicate a mildly alkalic rather than a subalkalic parent magma. Comparison of the Rossland volcanic rocks with those of recent island arcs, and consideration of the Upper Triassic – Lower Jurassic paleogeography in the Cordillera, suggest the rocks may be related to a localized oceanic basin, their extrusion being associated with faults bounding its western edge.
Thermal conductivity and specific heat of oil sand samples
Authors: Cervenan M. R. , Vermeulen F. E. , Chute F. S.
Published: April 2011

The thermal conductivity and specific heat of reconstituted samples of Athabasca oil sands were measured at room temperature. The samples originated from the SUNCOR mining operation and varied in bitumen and moisture contents. Thermal conductivity was deduced from the dependence of the thermal resistance of samples on sample thickness, with the samples being held in a hot plate configuration.The values obtained for thermal conductivity are correlated with pore-water saturation and are compared to values of thermal conductivity calculated from a single-fluid model involving only water saturation. Good agreement with the single-fluid model was observed for bitumen-free samples; however, samples containing bitumen at low water saturation show higher thermal conductivities than those predicted by the single-fluid model, suggesting a significant contribution by the bitumen to the thermal conductivity of these oil sand samples.Values of specific heat were obtained by conductive electrical heating of oil sand samples and by relating the increase in temperature to the electrical power supplied.
Variations spatiales et temporelles du césium-137 et du carbone dans des sédiments du fjord du Saguenay
Authors: Barbeau C. , Bougie R. , Côté J.-E.
Published: April 2011

The accumulation rate of sediments in the Saguenay Fjord, Quebec, Canada, established from 137Cs activity measured in 19 cores, varies between > 1.0 cm/year upstream and 0.2 cm/year downstream. Cesium-137 profiles in cores from the northern basin follow that of fallouts on the ground and reflect the impact of a sudden inflow of clay from a major mudslide. However, 137Cs accumulation in the larger basin seems less sensitive to external influences.Carbon content and the C/N ratio are higher upstream than downstream. Based on 137Cs dating, core sections show carbon contents that reflect changes caused by the forest industry over the years. [Journal Translation]
A newly recognized sequence of possible Early Cambrian age in southern New Brunswick: evidence for major southward-directed thrusting
Authors: McLeod M. J. , McCutcheon S. R.
Published: April 2011

Several previously unidentified occurrences of possible Lower Cambrian strata have been discovered recently in the Eastern Volcanic Belt (Avalon zone) of southern New Brunswick. The basal part of the sequence is lithologically similar to the Lower Cambrian parastratotype on Hanford Brook near Saint John, New Brunswick. Some of the newly recognized Cambrian rocks crop out beneath major northeast-trending and north-dipping thrusts, and rest unconformably on subaqueous Upper Precambrian equivalents of the Coldbrook Group. The presence of these Cambrian rocks in the Eastern Volcanic Belt indicates that the Cambrian–Ordovician Iapetus Ocean transgressed across the entire Avalon zone of southern New Brunswick.
Tectonic history of a segment of the Pelagonian zone, northeastern Greece
Authors: Nance Damian
Published: April 2011

Continental metamorphic rocks and ophiolitic bodies within the Pelagonian zone of the Hellenides in the Livadi area, northeastern Greece, show repeated periods of deformation that accompany thermal events of Early Cretaceous and possibly Late Eocene age. Structures associated with the earlier deformation indicate thrusting towards the northeast accompanying regional metamorphism of upper greenschist to lower amphibolite facies. Later structures and a retrogression to lower greenschist facies associated with emplacement of the Livadi ophiolitic rocks into their present position are likewise attributed to northeast-directed thrusting and probably accompanied the allochthonous movement of the Pelagonian basement over the Mesozoic platform carbonates of Mt. Olympos.Emplacement vectors of northeast polarity are inconsistent with tectonic models of the Hellenides involving large-scale southwestward obduction of Mesozoic ophiolites from a single ocean located northeast of the Pelagonian zone. Tectonic models involving the converging emplacement of Mesozoic ophiolites from two oceans lying northeast and southwest of the Pelagonian zone are more compatible with the observed structures, the latter ocean providing a potential root zone for the deformed ophiolitic rocks at Livadi.The orientation of minor structures associated with thrusting that postdates the emplacement of the Livadi ophiolitic rocks is consistent with movement from north to south.
A comparison of observed and theoretical postglacial relative sea level in Atlantic Canada
Authors: Quinlan Garry , Beaumont Christopher
Published: April 2011

Two extreme models of late Wisconsinan ice cover in Atlantic Canada and the northeastern U.S.A. are shown to produce postglacial relative sea level curves that bracket existing field observations at six sites throughout the region. This suggests that the true late Wisconsinan ice distribution is probably intermediate to the two contrasting reconstructions proposed. Both ice models predict the existence of four relative sea level zones: an innermost zone closest to the centre of glaciation in which relative sea level falls continuously throughout postglacial time; an outermost zone in which it rises continuously; and two transitional zones in which it first falls and then rises in varying proportions according to the distance from the ice margin. The distinctive forms of the relative sea level curves are probably representative of each of the zones and are unlikely to be significantly perturbed even by large local ice readvances. They, therefore, establish patterns with which future field data are expected to conform. The form that the geological record of relative sea level change is likely to take within each zone is discussed and promising settings for the collection of new data are proposed. The common practice of separating relative sea level into an isostatic and a eustatic component is analysed and shown to be incorrect as usually applied. The practice is also shown to be unnecessary because the models discussed in this paper predict changes in relative sea level that can be compared directly with the observations.
Distribution and chronology of freshwater marls between Kingston and Belleville, Ontario
Authors: Vreeken Willem J.
Published: April 2011

The distribution of 50 freshwater marl accumulation sites is compared with terrain attributes. All marl sites are underlain by clay and surrounded by terrain that is dominated by glacial till. Sites grouped in a western marl area appear to have been derived from thick calcareous till, but those in an eastern area are surrounded by thin till on highly jointed and fractured limestone bedrock. Many bottomland marls are in riverine locations, i.e., in the basins of the Collins and Millhaven Creeks and of the Salmon and Moira Rivers. About three quarters of the marl sites contain mantling peat.Sixteen radiocarbon datings disclose that marl formation began and ceased as early as 11 180 and 9330 years BP, respectively. Subsequent termination of marl formation transgressed time into the present: most upland sites stopped marl production prior to 8000 years BP and those that persisted dropped out between 6000 and 4000 years BP. Many bottomland marl sites changed into peat-forming sites between 4000 and 2000 years BP and show an apparent trend of progressive up-basin termination of marl formation. The causes of these trophic changes are speculated on from the soil–geomorphological perspective.
Early Cenozoic resetting of potassium–argon dates and geothermal history of north Okanagan area, British Columbia
Authors: Mathews Wm. H.
Published: April 2011

Unmetamorphosed Early Eocene sediments and volcanic rocks of the Trinity Hills and Enderby Cliffs yield K–Ar dates of 42–49 Ma. These overlie high-grade gneisses yielding K–Ar ages on biotites, muscovites, and hornblende ranging from 47 to 60 Ma. The Eocene sediments and volcanics rest nearby on low-grade phyllites, greenstones, and schists yielding dates from 83 to 155 Ma. The gneiss dates are regarded as reset by some Late Cretaceous to earliest Cenozoic thermal event that did not affect, at least to the same degree, the nearby less metamorphosed basement rocks. A thermal history has been constructed to account for the decreasing apparent ages of biotite (assumed blocking temperature of 250 °C) with increasing depth below the sub-Eocene unconformity, for the greater ages of hornblende and muscovite in the same rocks (blocking temperatures of 500 and 350 °C), as well as for thermal changes associated with high vitrinite reflectance from coal at one site in the covering sediments. Very rapid stripping (something like 5 km in 12 Ma) is inferred for the areas of reset gneisses, but not for the schist areas, in early Cenozoic time.
Physical and geochemical characteristics of suspended solids, Wilton Creek, Ontario
Authors: Ongley E. D. , Bynoe M. C. , Percival J. B.
Published: April 2011

To understand the nature of sediment-associated nutrient and contaminant transport dynamics in fluvial systems, a stormflow sampling program of suspended solids is reported for one water year in a representative rural diffuse source catchment of southeastern Ontario. Bulk samples of subsieve suspended solids were obtained using field-portable continuous-flow centrifuge apparatus. The physical and geochemical properties of suspended solids show no significant intersite differences over reaches of 1500–2000 m, yet display distinctive seasonal trends. Systematic seasonal changes in particle size, organic content, and Ca, P, Mn, Al, Ti, Fe, and K appear to reflect the changing role of partial area hydrology. Ca, P, and Mn are bioaccumulated by stream algae. Mineral signature is relatively constant over the year.
Remagnetization in Keweenawan rocks. Part II: lava flows within the Copper Harbor Conglomerate, Michigan
Authors: Halls H. C. , Palmer H. C.
Published: April 2011

Alternating field and thermal demagnetization studies of a thin lava flow unit within the Copper Harbor Conglomerate, Michigan Native Copper District, show a westerly increase in chemical remanent magnetization (CRM) overprinting along a 50 km strike length. The CRM may have formed while secondary minerals, including native copper, were being generated in the underlying Portage Lake volcanics, and when a rhyolite plug was injected into nearby siltstones of the overlying Freda Formation.The direction of magnetization during Copper Harbor time as given by the flows is virtually indistinguishable from that found from the Portage Lake volcanics, thus supporting previous geological observations that the two formations are closely associated in time.
Tectonic setting, rock chemistry, and metamorphism of an Archean gabbro–anorthosite complex, Tessiuyakh Bay, Labrador
Authors: Wiener Richard W.
Published: April 2011

The Tessiuyakh gabbro complex, an Archean complex of layered ultramafic, gabbroic, and anorthositic gneisses, has been discovered at Tessiuyakh Bay, Labrador. The complex is similar to Archean metamorphosed gabbro and anorthosite in Greenland and contains relict plagioclase phenocrysts and graded igneous layering, and has an olivine tholeiitic composition.The earliest recognized deformational features in the gabbro complex are isoclinal folds with axial plane metamorphic foliation. Thrust faults parallel to the foliation formed during the latter stages of isoclinal folding. The isoclinal folds and thrust faults are refolded by an open, south-southeast-plunging anticline, and all the above structural features are cut by undeformed, 2.4 Ga granite.Metamorphism associated with the early isoclinal folds attained amphibolite to granulite facies. The orthopyroxene "isograd" is largely a function of Mg/(Mg + Fe) in metamorphosed gabbros. A continuous hornblende breakdown reaction to orthopyroxene, augite, plagioclase, and oxide occurs in metamorphosed gabbros with [Formula: see text], whereas more Mg-rich gabbros lack orthopyroxene. Origin as oceanic layered gabbro is suggested for Archean gabbro–anorthosite complexes.
Atrypoidea species from the Canadian Arctic islands
Authors: Jones Brian
Published: April 2011

Species of Atrypoidea have the potential of being biostratigraphically useful for the Upper Silurian strata of Arctic Canada. Critical to any biostratigraphic scheme is the relationship between A. phoca (Salter, 1852) and A. scheii (Holtedahl, 1914) since there is disagreement as to whether these species are synonymous, or distinct and stratigraphically separate species. Detailed morphological analysis of topotype A. scheii from Goose Fiord, Ellesmere Island shows that it falls within the range of morphological variation displayed by topotype A. phoca from Cape Riley, Devon Island. Consequently, A. scheii is maintained as a synonym of A. phoca.Other new species that may prove to be biostratigraphically useful include Atrypoidea gigantus n.sp. from an unnamed formation at Goose Fiord and A. netserki n.sp. from member C of the Read Bay Formation on Beechey Island. Atrypoidea gigantus, the largest species of Atrypoidea so far reported from Arctic Canada, is closely related to Atrypoidea foxi (Jones, 1974). Atrypoidea netserki is morphologically closest to A. phoca.Although the Atrypoidea sequences in the Ludlovian and Pridolian strata of Arctic Canada are now better known it is still difficult to delineate exact evolutionary trends, possibly because the various species have a facies- as well as a time-controlled distribution.
Utilizing multi-channel airborne gamma-ray spectra
Authors: Dickson B. H. , Bailey R. C. , Grasty R. L.
Published: April 2011

Experimental studies using a large-volume sodium iodide detector system show how the potassium, uranium, and thorium gamma-ray spectra vary with altitude above the ground. The shapes of the spectra were derived from measurements on large radioactive concrete calibration slabs using plywood sheets to simulate the absorption of the gamma radiation in the air. A mathematical analysis of the data showed that within the range covered by the experiment (0–112 m of air) the spectra of each of the three radioelements are made up essentially of two spectral components, whose proportions vary with the amount of absorbing material between the source and the detector. With this knowledge, it is shown how all the basic information relating to source–detector distance and source concentration may be extracted from the airborne gamma-ray spectrum.
Carbone organique: indicateur potentiel de paléoenvironnements; deux exemples
Authors: Bertrand R. , Héroux Y.
Published: April 2011

The paleoenvironment of deposition and the total organic carbon (TOC) content of two sedimentary rock sequences are studied. One has a Cenozoic age and is located on the Labrador shelf; the other is early Paleozoic and is found in the St. Lawrence Lowlands. In both sequences, variations in the paleoenvironments correspond to changes in the TOC content, despite important differences between them (age, tectonic and general paleogeographic contexts, lithologies, nature of the organic matter).A statistical processing of the data is used in order to show this parallelism between the paleoenvironment and the TOC content. In both cases, the higher the TOC content, the greater is the distance of the depositional environment from the shore. This result is in agreement with the conclusions of many other authors. This method may be very useful for detecting bathymetric variations in depositional environments, especially in monotonous sequences.
Évolution thermique et potentiel pétroligène par l'étude des kérogènes, des extraits organiques, des gaz adsorbés, des argiles, du sondage Karlsefni H-13 (offshore Labrador, Canada)
Authors: Héroux Y. , Bertrand R. , Chagnon A. , Connan J. , Pittion J-L. , Kübler B.
Published: April 2011

The Tertiary sequence of the Labrador offshore (Karlsefni H-13 well) is formed by clayey–detrital lithologies for which thermal maturation and oil potential have been established.The kerogen of this sequence is ligneous (type III) but shows a slight tendancy towards a more sapropelic (type II) character between 2000 and 3300 m. The amorphogen, abundant throughout the borehole, is partly derived from the destruction of woody matter. The sapropelic trend of the kerogen corresponds to an increase of the organic carbon and amorphogen content. In this sequence, the best oil potential (fair to good) would be offered by the lithologies between 2000 and 3300 m, if the appropriate catagenetic zone had been reached.The amount of gas produced with respect to oil, in the 2000–3300 m interval, is a function of the thermal maturation. The oil window maturation stage (potential oil window (POW)) is reached at 3750 m. Two thermal maturation stages occurred before the POW: an upper dry gas (methane) stage (2160–2520 m) and an upper wet gas (condensate) stage (2520–3750 m). A biogenic gas zone (650–765 m) also occurs at the top of the unproductive immature zone. More than one analytical parameter must be used to differentiate these diagenetic stages. These parameters come from the physico-chemical and microscopic studies of the kerogens, organic extracts, adsorbed gases, and clay mineralogy.
Petrofabric and dielectric anisotropy in rock
Authors: Nowina S. , Strangway D. W.
Published: April 2011

There is a systematic relationship between anisotropy in the fabric of rocks and anisotropy in their dielectric properties, although the relationship is difficult to express in any quantitative sense. In general, the dielectric constant K′, the dielectric loss K″, and the real conductivity σ′ are a maximum when measured along the lineation axis (L) of rock, and a minimum when measured along the foliation normal (F). In this study, rocks were measured both vacuum dried and with varying degrees of water present; the anisotropy of wet rocks is greater than when vacuum dried, due presumably to anisotropic distribution of water parallel to the petrofabric. The effects of water, however, can be eliminated by means of measurements in vacuum or, more simply, by heat drying the sample, and subsequent impregnation of the rock with a hydrophobic low-loss dielectric material (paraffin wax). This is particularly significant since it greatly reduces the cost and time involved in this type of study.Dielectric anisotropy is frequency dependent. It was largest at the lowest measurement frequencies (30 Hz) and diminished with increasing frequency. For this and other reasons, dielectric anisotropy in rock is attributed to Maxwell–Wagner effects, which are low frequency relaxation phenomena related to the shape, size, and dielectric anisotropy in rock, reflecting primarily the grain-shape and grain-aggregate-shape fabric.
Peracarids (Crustacea) from Mississippian strata of western Newfoundland
Authors: Dewey Christopher P. , Fåhræus Lars E.
Published: April 2011

Tealliocaris sp. aff. T. loudonensis Peach (Peracarida, Crustacea) is reported for the first time from the Mississippian of North America. It is described from the Port au Port Peninsula of western Newfoundland where it occurs in a sequence of grey pelmicrites showing evaporitic solution features indicative of a hypersaline environment. The previously described peracarid Bellocaris newfoundlandensis Fong, which also occurs in the Port au Port area, has been found at several new localities in addition to the type locality. Bellocaris newfoundlandensis only occurs in buff-colored brachiopod–bryozoan packstones, occurring as karstic infill, where more normal marine water circulation probably was less inhibited.
The macroboring ichnofossil Trypanites in colonies of the Middle Ordovician bryozoan Prasopora: population behaviour and reaction to environmental influences
Authors: Kobluk David R. , Nemcsok Steven
Published: April 2011

A life-assemblage population (189 specimens) of hat-shaped (hemispherical) colonies of Prasopora spp. from the lowermost Verulam Formation (Middle Ordovician) at Kirkfield, Ontario contains macroborings referable to Trypanites Magdefrau.Scolecodonts, and other fragmentary microfossils, identify the organisms that made the borings as polychaete annelids. Fifty-two percent of the bryozoan colonies are bored, and some colonies contain as many as 83 macroborings. The polychaetes bored into dead bryozoan colonies, but it appears that the borers were selective in their choice of substrates: they chose large colonies with diameter/height ratios between 3:1 and 3:2. Concentration of high densities of borings on the sides of the colonies indicates that current direction, and probably also sedimentation related to current flow and turbulence over and around the colonies, were important influences on the borers.The tendency for borings to occur in some colonies and not others and (when they are present) to be numerous and clustered on one side of the colony suggests gregarious clumping behaviour.The polychaete worms that produced these Trypanites macroborings, therefore, were both gregarious and highly selective in their choice of substrate. They chose colonies that provided significant elevation above the local soft sediment substrate, and gave a preferred orientation relative to local currents.
Geothermal gradients in the Hinton area of west-central Alberta
Authors: Lam H. L. , Jones F. W. , Lambert C.
Published: April 2011

Temperature data from petroleum exploration well logs of 3360 wells in a region of west-central Alberta are used to estimate thermal gradients. A relatively high geothermal gradient (~36 °C/km) of oblong shape located near Hinton is observed. The axis of the anomaly strikes approximately southwest–northeast and passes through the Miette Hot Springs area. It appears that water is heated at depth in the Rocky Mountain disturbed region and travels eastward and toward the surface along fault planes.
The Winona Basin: structure and tectonics
Authors: Davis E. E. , Riddihough R. P.
Published: April 2011

A compilation of published and new geophysical data from the Winona Basin off northern Vancouver Island has allowed a detailed interpretation of the sedimentary and tectonic history of the region to be made. The basin is forming as a result of the asymmetric subsidence of a recently isolated lithospheric block that is slowly converging with the continental margin. The crust beneath the basin is young (1–5 Ma, increasing in age from southeast to northwest) and of normal oceanic thickness. It is virtually non-magnetic, however, probably because of its having been rapidly buried by turbidite sedimentation. Subsidence of the basin and uplift of the Paul Revere Ridge began in the Early Pleistocene (ca. 1.8 Ma) and, since that time, up to 8 km of turbidite sediments has accumulated in the basin. The nature of the fanning of the deposits suggests that the basin has been kept full throughout its history; the minimum average supply rate necessary to accomplish this is about 70 × 106 Mg year−1. This Pleistocene average is considerably greater than the present discharge rates of any of the major rivers in the area. Subsidence, indicated by the large gravity anomaly over the basin (−130 × 10−5 m s−2 (−130 mGal)) and by the tilting of sediment layers at depth, and convergence, indicated by folding of sediments throughout the basin fill, appear to be continuing at the present time. From the timing of various events associated with the formation of the basin, we conclude that the recent reorganization of spreading and the recent relocation of the Pacific–Explorer–America triple junction have occurred in response to the demands of local small plate motions that are controlled by the interaction of the small plates with the continental margin.
A method for the distinction of circular conical from cylindrical folds
Authors: Stockmal G. S. , Spang J. H.
Published: April 2011

Discrimination between conical and cylindrical folds is crucial where conical folds influence surrounding structural geometry or when geologic data are projected into cross sections. Poles to cylindrical and circular conical folds plot on stereographic projections along great and small circles, respectively. Best-fit great and small circles to a girdle of poles from a folded surface are calculated using a least-squares minimization computer subroutine, which is from the IMSL software library and is based upon the Levenberg–Marquardt algorithm. The minimized parameter is the sum of squares of the angular separations between all poles to the folded surface and the great or small circle. A nonparametric, signed rank test of Wilcoxon is then used to statistically discriminate between cylindrical and circular conical fold models. Statistical conclusions are checked against an applicable parametric F-test.A syncline and a flanking anticline near the northern termination of the Lewis thrust are used to demonstrate the method. The syncline is statistically cylindrical whereas the flanking anticline is statistically conical with a semi-apical angle of 26°.
Evidence for a genetic link between Sudbury breccias and fenite breccias
Authors: Dupuis L. , Whitehead R. E. S. , Davies J. F.
Published: April 2011

Petrographic and chemical data obtained from an occurrence of Sudbury breccia reveal that, although the gross compositions of matrix materials can be accounted for by mixing of comminuted host gabbro and quartzite, enrichments in K2O, Rb, TiO2, Zr, Y, Ba, Sr, and P2O5 also occur. These enrichments parallel those in "foreign" fragments of alkali gabbro and are quantitatively similar to, but quantitatively less than, those in some fenites. The Sudbury structure lies along the projection of a linear belt of alkali igneous intrusions and it is suggested that this occurrence of Sudbury breccia represents fragmented rock above an underlying fenite breccia and alkali igneous body. The data support an origin by processes related to a diatreme rather than extraterrestrial impact.
Caractéristiques isotopiques (18O, 13CO2, 3H) des écoulements dans une tourbière sur pergélisol au Nouveau-Québec
Authors: Dever Laurent , Laithier Michelle , Hillaire-Marcel Claude
Published: April 2011

The 18O – mean annual temperature relationship, which is known in organic matter, presents some anomalies in Sphagnum. A study of water flow and isotopic characteristics of an arctic mire (Leaf River, Ungava Peninsula) has been undertaken to explain these anomalies. The isotopic compositions of the water (18O, 13CO2, 3H) permit the determination of some hydraulic characteristics of a peat on permafrost: (1) evaluation of the lag time between a rainfall and the discharge; (2) evaluation of the residence time of the water; and (3) subsequent mixing parts. A relationship between the isotopic characteristics and the ombrotrophic or minerotrophic nature of the mire is observed. A δ18O value of −11‰ appears in the ombrotrophic zone and a value of −17‰ in the minerotrophic zone. The relative enrichment in 18O of the first one indicates a shorter residence time. The isotopic changes subsequent to rainfalls (with δ18O = −12.2, −14.5, and −19.1‰ differ in time and space: (1) a 2‰ change is observed within 24 h in the minerotrophic zone; (2) a 6‰ change appears almost instantaneously in the ombrotrophic zone. 3H values indicate that neither the meltwater from winter snow (with low 3H content), nor the meltwater from permafrost participates in the subsurface flow.
Chitinozoaires de l'Arenig supérieur (Zone D) de la Formation de Lévis, Québec, Canada
Authors: Achab A.
Published: April 2011

The Shumardia limestone that forms the upper part of the Levis Formation (Zone D) yields well preserved assemblages of chitinozoans.These assemblages seem to be characterized by a new species: Conochitina pirum. They also contain Fustichitina langei, Conochitina poumoti, and Conochitina cf. C. kryos species, which permit a comparison with Arenig microfaunas from Spitsbergen and Australia.The paleontological data, especially those given by graptolites, indicate that Zone D is of late Arenig age. This age determination is corroborated by the absence of lower Llanvirn chitinozoans in the samples studied.
Influence of permeability on wave-tilt of EM waves
Authors: Singh Ramesh P. , Lal Tarkeshwar
Published: April 2011

Theoretical studies on the influence of magnetic permeability on the amplitude and phase of electric and magnetic wave-tilt have been carried out in the frequency range 102–106 Hz over a homogeneous half-space Earth model. Computational results show a pronounced effect of magnetic permeability on the amplitude of wave-tilt measurements.
Late Quaternary geology of eastern Graham Island, Queen Charlotte Islands, British Columbia
Authors: Clague John J. , Mathewes Rolf W. , Warner Barry G.
Published: April 2011

A reconnaissance study of Quaternary sediments exposed in coastal bluffs on eastern Graham Island has revealed the presence of two major till units, each of which is underlain by glaciomarine stony mud, outwash sand and gravel, and laminated to massive silt and sand of undetermined origin. Sediment units below the surface drift are older than the radiocarbon dating limit. Sediments above this drift provide a nearly continuous record of geologic events from before 16 000 years BP until the present.Stratigraphic evidence and radiocarbon dates indicate that: (1) late Wisconsin glaciation of the coastal lowlands of Graham Island was weak and of short duration; and (2) a period of low sea levels during late Pleistocene time was followed by a transgression that culminated about 7500–8000 years ago when the sea was about 15 m higher relative to the land than at present. Marine regression during middle and late Holocene time produced wave-cut scarps, wave-cut benches overlain by littoral sediments, bars, spits, and beach and dune ridges.
The Ile Bizard intrusion, Montreal, Quebec—kimberlite or lamprophyre?
Authors: Raeside Robert P. , Helmstaedt Herwart
Published: April 2011

The Ile Bizard intrusion is a composite diatreme consisting of a pipe-like main body with cross-cutting pipes and dikes. The rock types include an intrusive breccia consisting of a kimberlite-like matrix bearing many xenoliths, a later tuffisite breccia that contains abundant autoliths, and two phases of xenolith-poor tuffisite breccia. All kimberlitic intrusive phases are more aluminous, iron-rich, and less magnesian than typical kimberlites, but more closely resemble kimberlites than alnoites.Xenolith rock types include sedimentary rocks, basement rocks, alloclastic fragments, autoliths, and ultramafic rocks. Phenocrysts and (or) xenocrysts of clinopyroxene, phlogopite, olivine, and magnesian titanomagnetite are common. Ultramafic xenoliths include websterites, orthopyroxenites, dunites, harzburgites, garnet and garne–spinel lherzolites, garnet websterites, and garnet clinopyroxenites. Banded xenoliths represent a cumulate phase in the upper mantle; the remaining ultramafic xenoliths are samples of unmelted mantle material. Temperature and pressure estimates for the garnet lherzolites, ranging from 880 to 980 °C and 2.1 to 2.8 GPa, do not outline a paleogeotherm.Mineralogical and chemical characteristics of the intrusive rocks and the xenolith suite are compatible with those of true kimberlites. The Ile Bizard diatreme is, however, closely related in space and time to the Oka carbonatite complex and Monteregian alkaline activity, and provides an example where a clear distinction between true kimberlites and lamprophyres of so-called central complex kimberlites cannot be made. This intrusion represents the deepest level of generation of Monteregian igneous activity in the form of potassic–utramafic (or kimberlitic) magmatism.
Biogeochemical expression of a classic dispersal train of metalliferous till near Hopetown, Ontario
Authors: DiLabio R. N. W. , Rencz A. N. , Egginton P. A.
Published: April 2011

Picea mariana (black spruce), Abies balsamea (balsam fir), Juniperus communus (juniper), Acer saccharum (sugar maple), Populus tremuloides (aspen), grasses, and their till substrate were sampled at a site of zinc mineralization in marble of the Grenville Province of southeastern Ontario. A classic dispersal train derived from the mineralization is defined by the distribution of mineralized boulders and by the areal extent of till that is enriched in zinc and cadmium; it is 70–200 m wide and at least 400 m long.The spatial distributions of zinc levels in leaf tissue of P. mariana, A. Balsamea, and grasses are also effective maps of the dispersal train. This results from strong relationships between plant metal levels and till metal levels across the full range of till metal levels. Metal levels in tree rings show a persistent decrease from older to younger wood.
Geochronologic interpretations of Pb isotope ratios in nickel sulfides of the Thompson Belt, Manitoba
Authors: Cumming G. L. , Eckstrand O. R. , Peredery W. V.
Published: April 2011

Lead isotopes in nickel sulfides from seven deposits in the Thompson Belt appear to record events of four distinct ages. The earliest and most prominent of these may represent the emplacement of the nickel ores and their ultramafic hosts.Typical massive and disseminated low-lead nickeliferous sulfides were selected for analysis, and several partitioning techniques were used in order to obtain information about the range of isotope ratios in different phases and fractions of the samples. The data were interpreted in terms of the isotopic systematics discussed by Gale and Mussett.Data from four deposits produce two well defined, parallel "primary" isochrons whose calculated mean slope corresponds to an age of 2320 ± 30 Ma. Interpretation of this date as the time of emplacement of the nickel deposits and their ultramafic hosts is consistent with geological evidence that points to a post-Archean, pre-Hudsonian age. The 2320 Ma date may be consistent, within probable error limits, with the age inferred from Rb/Sr data (2100 Ma) for deposition of metasedimentary rocks of the Thompson Belt, into which the ultramafic lenses were intruded (Brooks and Theyer).The other isotopically recorded events occurred at 2015 ± 15 Ma (possibly early folding of the Thompson Belt supracrustal rocks), 1620 ± 25 Ma (probably a late retrograde stage of the Hudsonian Orogeny), and 1125 ± 60 Ma (possibly a thermal event associated with emplacement of the Mackenzie dyke swarm).
Structures d'écoulement dans une caisse filonienne : le mécanisme d'intrusion télescopique et le concept d'intra-épontes
Authors: André Francis , Gagny Claude
Published: April 2011

A detailed study of the internal structure of a dyke has revealed the existence of three facies, separated by magmatic discontinuities termed intrawalls. Chemical data from rocks and minerals, noteworthy for their homogeneity, point to a comagmatic identity for the different facies.Magmatic fabrics and especially intratelluric mineral distribution across the dyke width permit us to propose flow models specific for each facies. From these data it appears that, for a given facies, the flow pattern (and the consequent mechanical differentiation) must be expressed in terms of rheological characteristics of the magma during its emplacement.The data as a whole (chemical, mineralogical, structural petrology) are integrated in a dynamic emplacement model of a single magma through a pipe, according to what we define as a telescopic intrusion model.
Évolution du débit liquide et de la charge solide d'un estuaire sub-boréal : rivière St-Jean, Québec (côte nord du golfe du St-Laurent)
Authors: Cataliotti-Valdina D. , Long B. F.
Published: April 2011

The hydrodynamics of the St. Jean River estuary, particularly the flow dynamics, was evaluated and the mixing mechanisms were studied for fluvial water – marine water. In order to realize this objective, two series of measurements were undertaken on the solid and liquid discharges: the first took place during the spring flood (May 1980), the latter in conditions of lowest level spring tide (August 1980).The average stream discharge is 1035 m3/s during floods and 85 m3/s at periods of lowest water level. When the stream discharges exceed 160 m3/s, the wedge of salt water is pushed out of the estuary and no reversed currents are present; there is only a reduction of current velocity at the mouth of the river.The quantities of solid particles in suspension vary from 96 mg/L during floods (65–95% mineral matter) to 4.6 mg/L for lowest water levels (58% mineral matter).The general behaviour of the St. Jean River estuary suggests a new type of environment, the subboreal estuaries. They are characterized by a Qm/Qf ratio close to the one observed for highly stratified estuaries, but the regime of the material in suspension does not fit with that of micro- or mesotidal estuaries of New England or with that of microtidal estuaries of western Europe. [Journal Translation]
Evidence of pre-late Wisconsinan glaciations on Labrador Shelf – Cartwright Saddle region
Authors: Josenhans H. W.
Published: April 2011

High-resolution Huntee and air-gun seismic reflection profiles from Cartwright Saddle indicate the presence of at least three major glacial advances, which deposited giacial till sequences up to 100 m in composite thickness on the bottom and flanks of the saddle. These tills are found in water depths up to 600 m, and their acoustic character suggests deposition from grounded ice. Grounded ice at such depths and the presence of tills extending to the shelf edge indicate major glacial episodes. A combination of surface morphology and high-resolution seismic profile data reveals the presence of an extensive lateral moraine that flanks the southern edge of the saddle, suggesting that an ice tongue filled the saddle. Numerous areas of pinch-out of the upper till are recognized along the lateral moraine and near the shelf edge. In the deepest part of the saddle, high-resolution seismic records across a core site obtained earlier by Vilks show the core penetrates the upper part of a postglacial stratified silt sequence overlying glacial till. Extrapolating the 14C date obtained by Vilks from this core suggests the minimum date for the underlying till is approximately 70 000 years BP. Thus there is no indication of late Wisconsinan till in the area.
Paleomagnetism of Archean volcanics and Proterozoic dikes in La Grande Riviere area of Nouveau-Quebec
Authors: Seguin M. K. , Sharma K. N. M. , Woussen G. , St. Seymour K. , Symons D. T. A.
Published: April 2011

Paleomagnetic results are reported for six Archean volcanics and six Proterozoic diabase dike sites in the La Grande Riviere basin using AF and thermal demagnetization. The area is now flooded so that future work is not possible. The limited geological and statistical data base makes interpretation of the results necessarily tentative. The dikes yield an A component pole at 84°W, 74°N from magnetization residing in higher stability domains, which likely reflects emplacement either at ~2150 or ~1825 or ~1650 Ma ago, and a B component pole at 33°W, 4°S residing in lower stability domains, which likely reflects metamorphism during the Hudsonian Orogeny at ~1725 Ma, or, less likely, during Grenvillian uplift at ~975 Ma. The volcanics appear to yield a prefolding C component pole at 28°W, 49°S that dates extrusion at ~2900 Ma and a postfolding D component pole at 306°W, 37°N that dates metamorphism by the Kenoran Orogeny at ~2600 Ma.
Paleomagnetism of Late Archean metavolcanics and metasediments, Abitibi orogen, Canada: tholeiites of the Kinojevis Group
Authors: Geissman John Wm. , Strangway David W. , Tasillo-Hirt Ann M. , Jensen Larry S.
Published: April 2011

Iron-rich and magnesium-rich basaltic tholeiites of the latest Archean Kinojevis Group, central Abitibi Belt, northeastern Ontario, contain a natural remanent magnetization that is generally multivectorial. The components in all units reside in essentially pure magnetite, not the original titanomagnetites (where x for Fe3−xTixO4 probably was 0.60–0.65). Any original TRM was lost by chemical reconstitution of the magnetic oxides in response to primary deuteric conditions, long-term burial, regional metamorphism to prehnite–pumpellyite facies, and possibly intrusion by Matachewan dikes. Data from contact tests with Matachewan dikes indicate that the units are indeed capable of retaining a very latest Archean – earliest Proterozoic field (e.g., D = 194.9°, I = −14.3°, k = 8.1, α95 = 7.9°; n = 45 vectors, 38 samples). High-coercivity, high-blocking-temperature directions from samples from other flows, corrected for nearly penecontemporaneous downwarping, are in only crude agreement with those of Matachewan dikes, possibly suggesting that these components reflect a general Late Archean – Early Proterozoic field for the Superior Province. The paleomagnetic data from Kinojevis tholeiites indicate the emplacement, burial, and tight downwarping of the 10 km or so of Kinojevis stratigraphy were nearly synchronous with Matachewan intrusion. The Kinojevis data by themselves cannot be taken as statistically reliable indicators of the pre- (or immediately post-) Matachewan geomagnetic field nor can temperature–time relations for magnetic viscosity be used to predict the preservation of a statistically reliable TRM in any of these units. Individual magnetization components were blocked over geologically short periods of time, whereas the ensemble of data from discrete flows must record secular variations, field excursions, and possibly long-term polar wander.
Acoustic waves: a finite difference film
Authors: McMechan George , Price Bill
Published: April 2011

A finite difference solution of the acoustic wave equation is an ideal basis for making movies since the computations naturally provide a series of frames at successive, discrete time increments. Each time frame contains a picture of the wave field present at that time. An example is illustrated in a short (~2.8 Min) 16 mm film that shows the dynamic response of a two-dimensional model to a point source. The model consists of a layer of varying thickness that overlies a half space. The film shows the point source expanding into a circular wavefront that is reflected, refracted, and diffracted by the model.