bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Studies on the Uranium Deposit of the Fay Mine, Eldorado, Northwest Saskatchewan
Authors: Morton R. D. , Sassano G. P.
Published: April 2011

The Fay Mine uranium deposit is composed of veins parallel to the foliation of the paragneisses and paraschists of the Fay Mine Complex, which in turn overlies the Donaldson Lake Gneiss and Foot Bay Gneiss, within the Tazin Group of the Beaverlodge District, northern Saskatchewan. A computer oriented study of 5500 strike-dip measurements of planar features within the Fay Mine reveals that the lowest member of the metamorphic sequence, the Foot Bay Gneiss, is unique in that it exhibits Kenoran (?) structures associated with F1, NW-SE or N-S trending folds. Subsequent to the Kenoran (?) folding, an Aphebian (?) sequence of sediments and volcanics, now represented by the Donaldson Lake Gneiss and the Fay Mine Complex, was deposited. NE-SW trending, Hudsonian, F2 folds then developed and extensive cataclasis was effected. The F2 structures also affected the uppermost, taphrogeosynclinal Martin Formation sediments and volcanics. The major faults of the district are thought to have been initiated either as F2-shear joints or F2-tension fractures and have undergone multiple movement over a long period of time. The pitchblende ± quartz ± carbonates ± hematite ± chlorite veins, classified as 'mobilized stratabound deposits', occur parallel to S2 foliation planes in the crests, troughs, or limbs of F2 folds, wherever minimal plunge is observed. Such deposits may have been generated during regional metamorphism by mobilization of uranium-rich fractions from the originally uraniferous Aphebian precursors of the Fay Mine Complex. Later movement of such major structures as the St. Louis Fault has apparently caused only local deformation and brecciation of the uraniferous veins and has caused no more than limited recrystallization.
P–Coda Evidence for a Layer of Anomalous Velocity in the Crust Beneath Leduc, Alberta
Authors: Somerville P. G. , Ellis R. M.
Published: April 2011

Previous seismic studies of crustal structure using short-period P-coda recorded in the vicinity of Leduc in central Alberta have indicated that serious discrepancies exist between the experimental observations and those based on a horizontally layered model of the crust in both the time and frequency domains.Using vertical-radial spectral ratios and synthetic seismograms, a modified crustal model has been derived which gives better agreement between experimental and theoretical results. This model involves the insertion of a layer several kilometers thick having large velocity contrast with respect to the surrounding media at the base of the Precambrian basement (12 km deep). The new crustal model is discussed in the light of evidence for a low velocity zone in the upper crust in certain continental regions.
Geochronology of the Canadian Shield in Northeastern Alberta II. Charles–Andrew–Colin Lakes Area
Authors: Baadsgaard H. , Godfrey John D.
Published: April 2011

The broad outline of the tectonic–metamorphic history of this area is reasonably clear. Whole rock U–Pb, mineral U–Pb, whole rock Rb–Sr, mineral Rb–Sr, and mineral K–Ar data have resulted in the recognition of a narrow discontinuous N–S zone of Archean (> 2550 m.y.) granitic material which may predate the surrounding widespread migmatitic–gneissic complex. Other N–S belts of younger granitic to dioritic plutons (1900 m.y.) intrude the gneissic complex. A last severe thermal metamorphic event sharply 'reset' mica K–Ar dates for all bodies in the area to 1790 ± 40 m.y. The recently identified Archean belt is located in the Allan fault zone: a complex major zone of weakness which has undergone repeated activation involving deep seated folding, mylonitization, and multiple intrusion, with late plastic deformation and recrystallization of the mylonite belts. The unraveling of the tectonic–metamorphic history of the area is greatly complicated by multiple metamorphic effects and the compositional heterogeneity of the para– and ortho–gneissic materials of the migmatitic–gneissic complex. Local uranium mineralization in this area is geochronologically related to intrusion of the younger granites and is essentially contemporaneous with the main early phase of uranium deposition in the Uranium City area of Saskatchewan.
Application of Water Temperatures to the Problem of Lateral Mixing in the Great Bear–Mackenzie River System
Authors: Mackay J. Ross
Published: April 2011

Cross-river temperature profiles were run in mid-June 1971 at approximately 20 km intervals from the confluence of the Great Bear and Mackenzie Rivers, at Fort Norman, N.W.T., to the Mackenzie Delta, a distance of 650 km. As the Great Bear River was cold, the Mackenzie River warm, and as temperatures were read to better than ±.01 °C in the field, the cross-profiles have provided a record of the lateral mixing of the two rivers. A flow distance of 500 km was required for nearly complete mixing. The 1971 cross-river temperature profiles and aerial infrared imagery taken in 1969 show a good agreement in the mixing pattern. It is suggested that where water temperature contrasts exist, temperatures, which can be read easily with a resolution of better than ±.01 °C, may serve as one of the easiest and most economical of the tracers suitable for mixing studies.
Ice Formed Beach Features from Lake St. Jean, Quebec
Authors: Dionne Jean-Claude , Laverdière Camille
Published: April 2011

Features characteristic of polar beaches: ice-pusb ridges, ice-contact cusps, shore-ice kettles, residual marks left by melting ice, ice-rafted sediments, meltwater and wind features, occur on the beach at Val Jalbert, Lake St. Jean, Quebec. This example shows that the area covered by so-called 'polar beaches' is not restricted to the Arctic and the Antarctic regions.
PL Waves and Crustal Structure in Canada
Authors: Poupinet G.
Published: April 2011

A study of the group velocity of PL for about fifty paths in Canada has been made. It is difficult to measure the dispersion of PL for long periods because two Airy phases arrive in the beginning of the wave train. It is also concluded that like Rayleigh waves PL waves cannot really give more than an S-velocity distribution because the partial derivatives in SV are too large compared to those in P for the period range where a reliable estimate of the dispersion can be obtained. The different dispersion curves are interpreted by looking for lateral variations of PL dispersion. As these curves have only one or two degrees of freedom, we label a curve with an index of dispersion. As in Santo's studies, this index is attributed to each region crossed by fitting the propagation times for a given period. Diagrams are then used giving the variation of the index with the average S velocity and the depth of the Moho. The structures found by this rather simple method are well correlated with tectonic regions and gravity measurements.
The Relationship of Atractodon stonei (Pilsbry) (Mollusca, Buccinidae) to the Pleistocene Stratigraphy and Paleoecology of Southwestern Nova Scotia
Authors: Clarke A. H. , Grant D. R. , Macpherson Elizabeth
Published: April 2011

The extinct Pleistocene buccinid gastropod Atractodon stonei (Pilsbry 1893), formerly known as Neptunea stonei (Pilsbry), has been found in a southern Nova Scotian deposit. The species had been previously reported only from (presumably) Sangamon deposits at Nantucket Island, Massachusetts and at other locations south to Cape Hatteras, North Carolina. Associated molluscs from all A. stonei deposits show that it probably lived in about 5 to 20 fm and in a climate like that of the present Acadian marine zoogeographic region.Although the Nova Scotian specimens produced radiocarbon ages of 38 000 years B.P. stratigraphic and paleoclimatological data indicate Sangamon age and the radiocarbon dates are presumed to be too young. Atractodon stonei may qualify as a useful Pleistocene (Sangamon) index fossil representative of relatively specific paleoecological conditions.
Rb–Sr Isotopic Systematics of the Foot Bay Gneiss, Donaldson Lake Gneiss, and Pegmatite Dikes from the Fay Mine, NW Saskatchewan
Authors: Sassano G. P. , Baadsgaard H. , Morton R. D.
Published: April 2011

Whole-rock Rb–Sr studies of metamorphic rocks and associated discordant pegmatites from the Fay Mine, NW Saskatchewan, confirm that the gneisses of the Beaverlodge area have a minimum age of 2100 m.y., while the pegmatites are 1975 ± 20 m.y. old. The amphibolite facies grade metamorphic suite reveals that a significant degree of 'open system' behavior (with respect to Rb and Sr) accompanied intense kinematic metamorphism, mineralization, and partial retrogression into the greenschist facies. In contrast, the pegmatites which exhibit minimal cataclasis, have apparently remained 'closed systems'.
The Point Bar Environment in the Mackenzie River Delta
Authors: Gill Don
Published: April 2011

Helicoidal flow and sediment sorting along the convex portion of shifting channels in the Mackenzie River Delta cause point bars to be composed of the coarsest material available to plant colonization. Sorting by aeolian action further reduces the fine fraction in point bar soils. Coarse-textured deposits maintain a lower water content and a higher soil temperature than other deltaic surfaces, thus nearly every point bar is colonized by a discrete plant association. This ecosystem is dominated by balsam poplar (Populus balsamifera), and the distribution of well developed poplar stands is restricted to point bars. The successional ecology of this ecosystem is discussed in relation to the point bar environment.
Fibrous Calcite, a Middle Devonian Geologic Marker, with Stratigraphic Significance, District of Mackenzie, Northwest Territories
Authors: MacKenzie W. S.
Published: April 2011

Fibrous calcite beds containing cone-in-cone structures occur in outcrops and in core and cuttings from the subsurface, at a constant stratigraphic position near the base of the Hare Indian Formation, throughout parts of Anderson, Peel, Mackenzie, and Great Bear Plains in the District of Mackenzie. These remarkably persistent beds have a maximum thickness of 2.75 in. (7 cm) and occur throughout an area of about 15 000 mi2 (24 000 km2). Their most northerly observed exposure is near the junction of Anderson and Wolverine Rivers, and the most southerly is at Powell Creek about 220 mi (354 km) away. The fibrous calcite marker beds are rock stratigraphie units that probably developed in partly consolidated muds close below the water/sediment interface in response to undetermined changes in the physicochemical environment. Organic material and plant remains in the surrounding sediments probably acted as catalysts to initiate nucleation and growth of the calcite fibers. The zone of fibrous calcite occurs within and delineates the approximate areal distribution of a sequence of sediments rich in organic remains, sediments favorable to the formation of petroleum source beds. Closely associated strata are likely to be of interest to industry.
Geobotanical Processes in the Saskatchewan River Delta
Authors: Dirschl Herman J.
Published: April 2011

The interactions of substrate, soil frost, groundwater levels, vegetation, and ongoing landscape-forming processes were studied in a portion of the Saskatchewan River Delta. Representative field transects were used to relate vegetation types to differences in relief and seasonal water table elevation. Seasonal soil temperatures were recorded from common community types, and peat stratigraphy was determined along several field transects.Vegetation zonations, extending from mixed forest on river levees to open lake water obviously reflect moisture gradients. However, increasing moisture availability is paralleled by declining nutrient availability, away from the levees, as peat accumulation prevents rooting in the mineral soil. Nutrient status and type and degree of peat accumulation are thus dependent on landform and water circulation. Three main physiographic divisions were recognized as a means of discussing the dynamics of vegetation/environment interrelationships; alluvial levees, open drainage basins, and closed drainage basins.Alluvial levees, paralleling stream channels, are generally well drained, nutrient-rich, and covered by mixed forest and tall shrub communities. Open drainage basins are characterized by slow circulation of mineral waters, favoring growth of minerotrophic fens and floating sedge mats. Closed drainage basins are more or less completely surrounded by raised levees. Their source of water is limited runoff from the encircling levees and precipitation falling onto the basins. Deep peat deposits are characteristic of these sites. Nutrient levels are lower than in open basins and sphagnum moss commonly occurs above the fen peat deposits. The slightly raised centers of these closed basins often support black spruce bog communities.
Imperial Mammoth and Mexican Half-Ass from near Bindloss, Alberta
Authors: Churcher C. S.
Published: April 2011

Mammals recovered from gravels lying about 100 ft (30 m) above the level of the Red Deer River on Highway 41, halfway between Bindloss and Empress, now comprise Mammuthus imperator and Equus (Asinus) conversidens in addition to the lion-like cat (Panthera atrox) previously recorded from the site. A post-Wisconsin age of greater than 8000 years B.P. is suggested for the deposit.
A Note on the Conditions of Formation of Melilite in the Oka Alkaline Carbonatite Complex, Quebec
Authors: Currie K. L. , Gelinas L.
Published: April 2011

The melilite of the Oka complex is chemically equivalent to a mixture of nepheline, wollastonite, and diopsidic pyroxene, a mixture which locally coexists with melilite. The melilite is proposed to result from reaction of this mixture with calcite. Thermodynamic analyses of the possible reactions suggest melilite formed between 800 and 890 °C (1073–1163 °A), and at CO2 pressures less than 2 kbars. Monticellite, a characteristic accompanier of melilite would form from dolomitic carbonate under the same conditions. Experimental data appear to show that all wollastonite-bearing alkaline rocks are emplaced at total pressures less than 3.5 kbars, and all plutonic nephelinitic rocks equilibrated at temperatures of less than 1000 °C (1273 °A).
Geomorphology and Quaternary History of the Mackenzie River Valley near Fort Good Hope, N.W.T., Canada
Authors: Mackay J. Ross , Mathews W. H.
Published: April 2011

The Mackenzie River displays a sharp change in geomorphic character at The Ramparts, a postglacially-developed rock-walled canyon near Fort Good Hope, N.W.T. Upstream for at least 70 km the river is cut into late-glacial and early postglacial lacustrine, deltaic, and floodplain sediments with radiocarbon dates of 11 000 to 11 500 years. These sediments are overlain by peat dating back 6120 radiocarbon years. Downstream the river reoccupies, for more than 350 km, a Pleistocene channel containing glacial and fluvial sediments yielding only dates beyond the range of carbon dating. Abandoned channels west of The Ramparts record the overflow, in early postglacial time, from a rock-rimmed lake athwart the newly developed Mackenzie drainage. The deepest of the channels, believed to have been abandoned in mid-postglacial time, contained a major waterfall with its plunge-pool floor close to present sea level. Free drainage from the foot of the falls to the ocean at the time it operated is indicated. Erosion continues along the Mackenzie River above The Ramparts but some aggradation occurs below it. Permafrost thaw and heavy rainfall contribute to landsliding along the river banks in both segments.
A Microearthquake Survey of the St. Lawrence Valley near La Malbaie, Quebec
Authors: Leblanc G. , Stevens A. E. , Wetmiller R. J. , DuBerger R.
Published: April 2011

In the summer of 1970, a microearthquake survey was conducted near La Malbaie, north-east of Quebec City. During 53 nights of recording, 28 events with [Formula: see text] and average focal depth of 10 km were recorded. Their epicenters form a cluster which coincides with other epicenters of the last four centuries and with the large meteorite crater structure of Charlevoix County. This coincidence in space infers a possible causal relation, as the weakened crust under the crater could yield more easily to the postglacial strain field acting over a broader region. The analysis of the data suggests that accuracy in micromagnitude calculations is improved by the use of station corrections for the crustal effect. Distant local earthquakes may be used to calibrate each site. The observed seismicity in the La Malbaie area appears to be low and normal. Future surveys and permanent monitoring are needed to understand the tectonics of the St. Lawrence Valley.
Theoretical Frequency Distributions for the Analysis of Plains Streamflow
Authors: Spence Edward S.
Published: April 2011

Several different frequency distributions are in common use in the frequency analysis of hydrologic events. Two two-parameter frequency distributions, the Normal and the Lognormal, are tested for best fit in the frequency analysis of available annual yield data series; and four two-parameter frequency distributions; the Normal, the Lognormal, the Gumbel, and the Log-Gumbel are tested in the frequency analysis of annual flood flow data series for 161 drainage basins in the Canadian Plains. The relative best fits are established by data transformation and subsequent linear correlation and regression analyses. The bases for comparison are the resulting correlation coefficients. It is demonstrated that of the distributions tested, the two-parameter Lognormal distribution provides the best fit for the frequency analysis of both the annual yield and annual flood flow data series for plains basins.
Seismic Spectra of Yucca Flat Underground Explosions Observed at Yellowknife, Northwest Territories
Authors: Manchee E. B. , Hasegawa H. S.
Published: April 2011

Various features of the spectra of underground nuclear explosions, as recorded at a distant seismic station, may be explained by comparison with theoretical spectral amplitude curves constructed using known source, travel-path and receiver parameters.
The Lower Ordovician Brachiopod Syntrophla sp., cf. S. arethusa (Billings 1862) from South Catcher Pond, Northeastern Newfoundland
Authors: Boucot A. J.
Published: April 2011

The Lower Ordovician North American Province brachiopod genus Syntrophia is recognized for the first time from northern Newfoundland. It occurs together with other Lower Ordovician fossils (trilobites and conodonts) in a limestone lens interbedded with volcanic rocks that may belong to the Lush's Bight Group.
An Integrated Model for Lead Isotopic Evolution for Samples from the Canadian Shield
Authors: Ozard J. M. , Slawson W. F. , Russell R. D.
Published: April 2011

Values reported during the last 15 years for lead isotopic ratios of 10 suites of samples were normalized to absolute values. Inferior, duplicating sets of analyses were discarded. It was postulated that the broad features of the isotopic patterns should be explicable in terms of a small number of major tectonic events. A table of times for these events was prepared on the basis of isochron fits to the individual suites. The times correspond closely with the original interpretations made for the suites.The 30 possible time values were reduced to six distinct events. A modified two-stage model was used to represent each suite and times were selected for the model from the six events, by choosing those events that best described the suite. Residuals were calculated corresponding to a simultaneous least squares fit of all the data. From the minimum value of the sum of the residuals, optimum time values were obtained of 3470 ± 60, 3040 ± 10, 2630 ± 20, 2250 ± 20, 1500 ± 40, 920 ± 30 m.y. Uncertainties quoted are approximately one-sigma values. Thus it was possible to fit all the Canadian Precambrian data used in this study with six time values.The parameters μ = 8.79, t0 = 4580 m.y., a0 = 9.346, b0 = 10.218 as found by Cooper et al. were used for the first stage of the model.
Magnetic Anomalies of Precambrian Shields and some Problems of their Geological Interpretation
Authors: Krutikhovskaya Z. A. , Pashkevich I. K. , Simonenko T. N.
Published: April 2011

The predominance of extended zones of linear anomalies as well as of curved, ring-shaped, and other complicated anomalies, is characteristic of the magnetic field over ancient shields and platforms. The zones of linear anomalies reflect large tectonic features of the ancient geosynclines—deep faults and the associated structural facies zones. Curved anomaly zones characterize regions of deep-seated folding which are peculiar to ancient shields and platforms.Three large groups of deep structures may be distinguished in terms of the magnetic effects they produce. The first group includes domes (arches) composed essentially of nonmagnetic granitoids surrounded by stable magnetically active metamorphic zones. Structures of this group are most extensively developed in the inner zones of ancient geosynclines.A characteristic feature of the second group is magnetic anomalies over migmatite domes, whose minima extend over bordering synclines composed of nonmagnetic rocks. The trend of individual magnetic horizons is concordant with the direction of banding in the migmatites.The third group includes deep structures whose synclinal and anticlinal forms are composed of rocks showing an increased magnetization. Mapping of such structures in the magnetic field presents considerable difficulties.The autocorrelation functions of anomalous magnetic fields over ancient shields indicate the intricate nature of the fields. A zero-correlation radius of a high-frequency component ranges from 5 to 10 km; that of a long-wave component amounts to about 40 km.Two layers corresponding to the sources of anomalies are identified in the crustal cross section. The depths to lower boundaries of the bodies responsible for the local magnetic anomalies have shown that most of the sources are confined to a surface layer which is not more than 10 km thick. The source of regional magnetic anomalies is attributable to magnetic inhomogeneities of the earth's crust, lying at depths from 10 to 30 km.
The Topographic Effect in Electromagnetic Fields
Authors: Ku C. C. , Hsieh M. S. , Lim S. H.
Published: April 2011

By making use of the analogy between the network quantities and the electromagnetic fields, a numerical method is employed to investigate the possible topographic effect in the earth's EM fields for several simple models in two dimensional problems. It is found that various topographies may give rise to distortions in the earth's EM fields, and some EM anomalies observed on the ground surface may be simply due to such a topographic effect.
The Principle of Constituent Analysis, with Special Reference to the Calculation of Weight Percentages of Minerals in Metamorphic Rocks
Authors: Fuh Tsu-Min
Published: April 2011

The principle of constituent analysis is introduced. Assuming that a component (end member) consists of n variables in percentage form and that m different components (m ≤ n) constitute each of N samples, the samples can be treated as N points in m-dimensional space. Points represented by m end members are characterized by being non-coplanar and non-collinear in m-dimensional space. The amount of the mth end member contained in a sample is calculated as Xm−1i/Xm−1 m, where Xm−1 is the length of (m−1)th orthogonal axis; i and m in subscript Xm−1 are for the sample and mth end member, respectively; and the end members are successively put on the origin of the coordinate, X1, X1−X2, X1−X2−X3,…, and X1−X2 …−Xm−1 axes.In a metamorphic rock, m points are equivalent to constituent minerals. If the chemical compositions of constituent minerals and the bulk chemical composition of the rock are known, the method outlined in this paper provides information on equilibrium assemblages and allows computation of the amounts of constituent minerals.
Isotopic Compositions of Selected Ore Leads from Northeastern Washington
Authors: Small W. D.
Published: April 2011

Isotopic composition of ore leads from four districts in northeastern Washington has been measured with a precision in the ratios of about 0.1‰. Results indicate that the mineralization in the Marshall Diorites of Pend Oreille County is by a primary type lead with a model age of about 1300 to 1500 m.y. The remainder of the measured leads from Pend Oreille and Stevens Counties have a radiogenic component which could have developed in a closed system during the interval 1370 to about 250 m.y. ago. Leads from Ferry and Okanogan Counties have only slight variations in their isotopic abundances. These latter leads could have been produced by an homogenization of the leads from Pend Oreille and Stevens Counties through the mechanism of a late Mesozoic metamorphism of Mesozoic sedimentary structures in Ferry and Okanogan Counties, these latter sedimentary structures being the products of erosion of rocks in Pend Oreille and Stevens Counties. There is no evidence of an ancient basement structure under Ferry and Okanogan Counties from the data presented herein. The lead isotope composition of the ores from northeastern Washington is compatible with the current concepts of the crustal structure across the Canadian Cordillera.
Variation in the Composition of Muscovite and Biotite in some Metamorphic Rocks near Bancroft, Ontario
Authors: Rambaldi Ermanno R.
Published: April 2011

A study of mica composition in a metamorphic terrain which displays a variation in metamorphic grade from the garnet to the sillimanite–garnet–biotite zone, has revealed that muscovite and phengite occur over the whole range of metamorphic conditions that were encountered. The distribution of Mn, Li, Ti, Na, Fe, and Mg between these minerals and coexisting biotite shows many regularities which are interpreted in relation to exchange equilibrium. Two trends of element distribution are suggested, corresponding to the association phengite–biotite and muscovite–biotite. The chemical composition of the mica minerals is not correlative with metamorphic grade.A compositional study of phengite has revealed that the Fe2+/Fe3+ ratio in this mineral is higher in rocks that contain epidote than in rocks that are free of epidote.The distribution of Na and K between muscovite and plagioclase is affected by the Fe content of muscovite and the An content of plagioclase.Mineralogical and chemical data from the study area provide an indication that a generalized chemical equilibrium was established in the rocks during metamorphism.
The Growth of Pingos, Western Arctic Coast, Canada
Authors: Mackay J. Ross
Published: April 2011

The growth rates of 11 closed system pingos have been measured, by means of precise levelling of permanent bench marks anchored well down into permafrost, for the 1969–1972 period. As pingo growth decreases from the summit to the base, growth of the ice-core decreases from the center out to the periphery. The pingos have grown up in the bottoms of lakes which have drained rapidly and thus become exposed to permafrost aggradation. The specific site of growth is usually in a small residual pond where permafrost aggradation is retarded. The size and shape of a residual pond exercises a strong control upon the size and shape of the pingo which grows within it. The ice-core thickness equals the sum of the pingo height above the lake flat and the depth of the residual pond in which the pingo grew. Pingos tend to grow higher rather than both higher and wider. Pingos are believed to grow more by means of ice segregation than by the freezing of a pool of water. The water source, and the associated positive pore water pressure, result from permafrost aggradation in sands and silts in the lake bottom under a closed system with expulsion of pore water. The fastest growth rate of an ice-core, for the Western Arctic Coast, is estimated at about 1.5 m/yr, for the first one or two years. After that, the growth rate decreases inversely as the square root of time. The largest pingos may continue to grow for more than 1000 yr. Four growth stages are suggested. At least five pingos have commenced growth since 1935. As an estimate, probably 50 or more pingos are now growing along the coast.
The Frequency Dependence of the Perturbation Fields due to Conductivity Inhomogeneities in the Earth
Authors: Jones F. W. , Ainslie B. A.
Published: April 2011

The geomagnetic perturbation fields due to conductivity discontinuities in the Earth are investigated. Two models, one in which the discontinuity extends to infinite depth, and a second one which consists of a dike of finite depth are considered. The perturbation fields are studied for several different frequencies of the alternating inducing field for each model. Both the H-polarization and E-polarization cases are considered and the perturbation field component profiles as a function of height above the surface of the conducting region are studied. The perturbation fields are strongly dependent on frequency, and significant differences are exhibited between the H-polarization and E-polarization cases.
Calc-Alkaline Volcanism and Plutonism from the Great Bear Batholith, N.W.T.
Authors: Badham J. P. N.
Published: April 2011

The Camsell River – Conjuror Bay area is a pendant of Aphebian intermediate and felsic volcanic rocks, lying in a granitic complex, and is part of the Great Bear batholith. This batholith complex has been interpreted as being the orogenic belt of the Coronation geosyncline.Twenty-four analyses of volcanic and plutonic rocks are presented; these show that, in spite of alteration, the rocks can be classified as comagmatic and part of an alkali-rich calc-alkaline suite. The suite is chemically similar to younger suites from continental-margin orogenic belts. These similarities support proposals that the Coronation geosyncline was of Andean type and that the magmas may have been generated by subduction.
A Late Pleistocene Marine Shell Deposit at Shippegan, New Brunswick
Authors: Thomas Martin L. H. , Grant Douglas R. , Grace Marius de
Published: April 2011

Twenty species of marine invertebrate shells from a gravelly sand deposit close to the present shore at Shippegan, New Brunswick, were identified and shown to be typical of a shallow-water association formed soon after glacial retreat. One specimen yielded a radiocarbon date of 12 600 ± 400 yr. This evidence strengthens previous conclusions on the date of Pleistocene deglaciation and on postglacial sea-level changes in this area.
Permian Sponges from Western Ellesmere Island, Arctic Canada
Authors: Rigby J. Keith , Terrell Forrest M.
Published: April 2011

Sponges occur widespread in Permian formations in western Ellesmere Island on Fosheim, Raanes, and Bjorne Peninsulas. Scheiia tuberosa Tschernyschew and Stepanov, 1916, is described from the Assistance and Tanquary formations and is the most widely occurring sponge in the collections. Haplistion arcticum (Dunikowski, 1884), Haplistion latituba (Dunkowski, 1884), Haplistion diactinum n. sp., and Raanespongia monilis, n. gen. and n. sp., all occur in the Assistance Formation. Raanespongia monilis n. sp. is the basis of the new family Raanespongiidae which is included in the Eutaxicladina.
The Paleomagnetism of the Otish Gabbro from North of the Grenville Front, Quebec
Authors: Fahrig W. F. , Chown E. H.
Published: April 2011

The Otish Gabbro, which intrudes the Otish Mountains Group, is normally magnetized and has a paleomagnetic pole at 107 °W, 35 °N, α95 = 9°. The Otish Mountains Group has been correlated with the Mistassini Group and/or the Huronian Supergroup. The pole for the Otish Gabbro lies between that of the 2175 m.y. old Nipissing diabase, which is intrusive into Huronian strata, and the pole for the 1700 m.y. old Sudbury norite. If the Otish Mountains Group is correlative with the 2300 m.y. Huronian, the Otish Gabbro was intruded a considerable time after the deposition of the sedimentary strata.
Fabric Variation in the Lubec–Belleisle Zone of Southern New Brunswick
Authors: Garnett John A. , Brown Richard L.
Published: April 2011

Variations in structural fabric adjacent to part of the Lubec–Belleisle fault are interpreted in terms of a single protracted heterogeneous strain. Zones of shallow and intermediate pitch of lineation in steep to vertical surfaces occur between a region of steeply pitching lineations and a region of unstrained rock. Finite strain in the zone of steeply pitching lineations is greater than in the intermediate or shallow pitching zones. The variation in magnitude and orientation of the finite strains is probably due to a buttressing effect of adjacent unstrained granitic rocks.The fabric zones formed in Middle Devonian times, and predate brittle movement of the Lubec–Belleisle fault. Since the zones do not display appreciable horizontal displacement, the possibility of major strike-slip movements along this fault must be ruled out.
Structural Cross-Section and Tectonic Model of the Southeastern Canadian Cordillera
Authors: Campbell R. B.
Published: April 2011

Recent models for the structural evolution of the southern Canadian Rocky Mountains have emphasized 'thin-skinned' tectonics whereby thrust sheets piled up from west to east above a décollement on a passive crystalline basement. The concept implies that the more westernly Omineca Crystalline Belt, including granitoid gneiss believed to be basement more than 800 m.y. old, is allochthonous and has moved eastward by at least the amount of shortening in the thrust-faulted zone.Mildly deformed and metamorphosed stratified rocks in the northern Columbia Mountains (central Omineca Crystalline Belt) and adjacent Rocky Mountains permit construction of well-controlled structural and restored stratigraphic cross-sections, which show that the Crystalline Belt and Main Ranges were relatively uniformly uplifted by about 35 000 ft (11 km) whereas flanking regions experienced minor uplifts. Combined with other evidence this indicates that 'thick-skinned' tectonics with vertical movements of the entire crust affected the Omineca Crystalline Belt and the Main Ranges; major horizontal movements seem unnecessary. The Omineca Crystalline Belt is regarded as an autochthon in which the basement was extensively deformed and it is suggested that basement is deformed beneath the Main Ranges. The zone of thrusting and décollement above the basement is restricted to the Front Ranges and Foothills and may result from westward underthrusting of the craton.
Stable Magnetization in a Gabbro from the Giles Complex, Central Australia
Authors: Facer R. A.
Published: April 2011

Remanence of high stability has been detected in a gabbro specimen from the Hinckley Range (Giles Complex), although it was not observed in other rocks from the Complex. This occurrence is another example of high magnetization stability in coarse-grained mafic intrusive rocks.
Gravity Profiles across Ice-Cored Topography
Authors: Rampton V. N. , Walcott R. I.
Published: April 2011

Gravity profiling at five different sites in an area of ice-cored topography indicates the usefulness of the technique as a method for the detection of ground ice and for estimating the thickness of the excess ice. Bouguer anomaly profiles using a density of 2.0 Mgm−3 provide a quick method of assessing the relative amount of ice along a profile, the thickness of ice and the elevation being inversely proportional to the Bouguer anomaly value along each profile. The average amount of excess ice in the topography along the profiles is obtained by removing linear trends, obtaining the Bouguer density of the topography, and calculating the proportion of frozen saturated sediment and ice required to produce this density. Variations in the thickness of the body are obtained from significant gravity residuals. Finally, models are given to show the distribution of the excess ice with the aid of supplementary information. The above technique is unable to detect changes in the amount of excess ice that have a linear trend over the complete profile or a uniform slab of ice underlying the complete profile. A model for a pingo is constructed using stacked concentric cylinders. Geologic data from the region indicate that all models give reliable estimates of the amount of excess ice and probable thermokarst subsidence if the area were thawed.
A Study of Seismic Risk near Pipeline Corridors in Northwestern Canada and Eastern Alaska
Authors: Stevens A. E. , Milne W. G.
Published: April 2011

Seismic risk in the Yukon Territory and adjacent areas of the western Northwest Territories and eastern Alaska is evaluated from locations and magnitudes of earthquakes in northern Canada and Alaska from 1899 to 1970. Contour maps illustrate strain release and also predicted accelerations on firm soil for return periods of 30, 50, and 100 years. Calculated values of these risk parameters may vary by a factor of two or more from actual values due to the short earthquake history of the region studied, uncertainties in location and magnitude of past large earthquakes, lack of measured ground accelerations in the regions, and the unknown modifying influence of soil and subsoil materials.Seismic risk may be significant for parts of the Mackenzie Valley pipeline corridor in the vicinity of Fort McPherson between mile 700 (east of Arctic Red River, Northwest Territories) and mile 850 (east of Old Crow, Yukon Territory).
Time-Series Analysis of Groundwater Hydrographs from Surficial Deposits on the Canadian Shield
Authors: Jackson R. E.
Published: April 2011

The natural, groundwater hydrograph of water-table levels reflects the dynamic response of the groundwater flow system to climatic stimuli. Consequently time-series analysis has been employed to examine the frequency structure of long-term climatological and hydrogeological records, and to compare hydrographs from different parts of Northern Ontario, which are known to experience considerably different climatic regimes. The results of the study show that the soil–moisture zone filters out high-frequency climatic cycles before they reach the water table. Furthermore by dividing groundwater hydrographs into a deterministic component, the mean annual hydrograph, and a stochastic component, the residual time series, it is shown that only hydrographs of observation wells within the same hydrogeological subregion have deterministic components with coincidental inflection points and stochastic components that are inphase and coherent. It is also shown that the amplitudes of the deterministic components vary rather unpredictably, and that the variance spectra of the stochastic component of hydrographs from the same hydrogeological region tend to be similar irrespective of climatic differences within the region.
Application of Regression Analysis to Interpretation of Geochemical Data from Lake Sediments in Central British Columbia
Authors: Spilsbury W. , Fletcher K.
Published: April 2011

Multiple regression is used to investigate relationships among copper, zinc, iron, manganese, organic matter, sand content, and pH of nearshore lake sediment samples from small lakes in central British Columbia. Iron and sand content are shown to be the principal factors influencing regional distribution of copper and zinc.
Basement/Cover Relationships Within the Grenville Province in Eastern Ontario
Authors: Appleyard Edward C.
Published: April 2011

In the vicinity of the western boundary of Renfrew County, eastern Ontario, in an area between Barry's Bay and Rosenthal, supracrustal metamorphic tectonites of the Grenville Supergroup structurally overlie a migmatite complex known as the Radcliffe Hybrid Gneiss. It is shown that the latter can be subdivided by qualitative structural analysis into two units of differing tectonic complexity. A polymigmatitic unit displaying the effects of at least five phases of deformation and containing at least the same number of leucosomal phases lies to the northwest of a less complex migmatitic unit displaying three phases of deformation and only two leucosomal phases. The former is identified as pre-Grenvillian basement and the latter as the basal portion of the Grenville Supergroup cover sequence which was transgressed by a rising migmatite front during the Grenvillian orogeny. Criteria for distinguishing basement and cover migmatites are discussed in the local context as are some problems involved in mapping tectonostratigraphic units in migmatite terrains.
Mud Cracks and Polygons on Ice Push Ridges, in Tidal Flats of the St. Lawrence Estuary
Authors: Dionne Jean-Claude
Published: April 2011

Mud cracks and polygons form during summer in tidal flats of the south shore of the St. Lawrence Estuary. They occur near mean low water level at the top surface of ice push mud ridges formed during winter and break-up. They are a source of mud clasts which settle in the surroundings when carried away by waves and currents.
Geology and Age of some Plutons in North-Central Gaspe, Canada
Authors: de Römer H. S.
Published: April 2011

North-central Gaspe is characterized by three conspicuous leucocratic stocks intruded into Cambro-Ordovician and Siluro-Devonian formations: Monts McGerrigle, Hog's Back, and Mont Vallieres-de-St, Real. The Monts McGerrigle pluton, the largest of these, is a discordant multiple intrusion surrounded by a striking 1–2 mi (1.6–3.2 km) wide aureole of hornfels and skarn, reaching a prevalent hornblende–hornfels facies near the contact. A quartz-poor, possibly contaminated acid magma invaded an early gabbroic phase resulting in hybrid rocks laden with xenoliths. Subsequently, the mass was intruded by red granite and granite porphyry. Depth of intrusion was probably shallow corresponding to a total pressure of approximately 2 kb. Field evidence indicates that Hog's Back and Mont Vallieres-de-St. Real are satellitc quartz–sodic feldspar porphyries connected in depth to the Monts McGerrigle pluton. While the latter intruded post-kinematically into Cambro-Ordovician rocks, the porphyries were emplaced in the form of semi-concordant hypabyssal sheets in Siluro-Devonian formations. Radiometric dating suggests a late Devonian intrusion. Patchy distribution of thermally altered rocks in the area between the stocks indicates an irregular profile of a large igneous mass not far below surface.
Rb-Sr Age of the Late-Kinematic Phase of the Hudsonian Orogeny in the Beaverlodge Area, Saskatchewan
Authors: Sassano G. P. , Baadsgaard H. , Burwash R. A.
Published: April 2011

The Tazin Complex, north of Lake Athabasca, shows widespread development of mylonites associated with northeast trending faults. Hudsonian metamorphism has caused recrystallization of cataclastic rocks with post-crystalline deformation forming narrow zones of later mylonites. Syenitic lamprophyre dikes which, with very few exceptions, are undeformed, form the latest intrusive rocks in the area, filling dilatant fractures developed during crustal uplift.Rb–Sr whole rock dating of eight samples of the dikes in the Beaverlodge area, yield an isochron of 1779 ± 72 m.y. (initial ratio = 0.709 ± 0.001, MSWD = 0.39, λ(87Rb) = 1.39 × 10−11/yr). The late-kinematic phase of the Hudsonian orogeny, therefore, occurred around 1780 m.y. ago, at which time the uplift of the northwestern sector of the Churchill structural province look place. It is also believed that the date is close to the time of final movement of the St. Louis Fault.
Pulse Calibration and its Application to the Daily Calibration of the Canadian Standard Seismograph Network Long Period Seismometers
Authors: Wickens A. J. , Hasegawa H. S. , Bone M. N.
Published: April 2011

The Canadian Seismograph Network long period instrument parameters are used to calculate theoretical output response curves to various input functions. These curves were used as overlays to the actual response of the instruments to a known input pulse sequence. This provides an independent means of determining instrument response as well as daily monitoring ability.
Spurious K–Ar Ages due to Radio-Frequency Induced Electrical Discharges in Argon Extraction Systems
Authors: Baksi A. K.
Published: April 2011

The radio-frequency induction heating technique can lead to electrical discharges in argon extraction lines. Under these conditions, loss of argon and isotopic fractionation may occur, leading to incorrect K–Ar ages.
Glacial and Paraglacial Genesis of Conglomeratic Rocks of the Chibougamau Formation (Aphebian), Chibougamau, Quebec
Authors: Long Darrel G. F.
Published: April 2011

Conglomeratic rocks of the Chibougamau Formation are interpreted as the products of deposition in a glacial and paraglacial environment, in an area of undulating topography at the margin of an extensive Aphebian ice sheet. Mixtiles and graded laminites with dropstones were deposited in a glacial and proglacial lacustrine environment. Intact framework conglomerates, conglomeratic sandstones and massive sandstone units were produced on alluvial fans in a paraglacial environment, predominantly as debris flows. Correlation between the Chibougamau Formation and the Huronian Gowganda Formation of Ontario is consistent with the environmental interpretation of both formations.
Radiometric Age of the Keppoch Formation, Browns Mountain Group, Northern Mainland of Nova Scotia
Authors: Cormier R. F.
Published: April 2011

The lower Paleozoic Browns Mountain Group of volcanic and sedimentary rocks underlies much of the Antigonish Highlands on the northern mainland of Nova Scotia. The rocks are apparently unfossiliferous and pre-Lower Silurian in age. Volcanic rocks belonging to the Keppoch Formation give a Rb–Sr whole-rock isochron age of 528 ± 40 m.y.; the indicated value for the initial ratio 87Sr/86Sr is 0.7032 ± 0.0020. The apparent stratigraphic age of the lower part of the Browns Mountain Group then is Cambrian with a middle Cambrian age favored.
The Rubidium–Strontium Whole-Rock Age of Major Units of the Chibougamau Greenstone Belt, Quebec
Authors: Jones L. M. , Walker Raymond L. , Allard Gilles O.
Published: April 2011

Suites of samples from the Dore Lake Complex, the Chibougamau Pluton, and the volcanic Roy Group were analyzed for an age determination by the Rb–Sr whole-rock isochron method. The rocks of the Dore Lake Complex became a closed system with respect to Rb and Sr 2573 ± 234 m.y. ago (λ87Rb = 1.47 × 10−11 yr−1) with an initial 87Sr/86Sr ratio of 0.7009 ± 0.0005. The Rb–Sr age of the Chibougamau Pluton is 2424 ± 79 m.y. and (87Sr/86Sr)0 = 0.7005 ± 0.0002. Mineral separates of both the Dore Lake Complex and the Chibougamau Pluton do not lie on the respective isochrons and do not form isochrons of their own. The samples from the Roy Group form a poorly-defined isochron of 2206 ± 85 m.y. with (87Sr/86Sr)0 = 0.7018 ± 0.0003. The Chibougamau Greenstone Belt has apparently been affected by the Kenoran orogeny, after which the rocks seemingly have remained closed with respect to rubidium and strontium. The initial 87Sr/86Sr ratios of these units probably represent the isotopic composition of strontium in the upper mantle about 2.5 b.y. ago.
On the Quality of Some Waters on Baffin Island, Northwest Territories
Authors: Church Michael
Published: April 2011

In glacierized and nonglacierized river basins in eastern and central Baffin Island, waters are generally very soft (total dissolved solids of order 5–50 mg/l). Diurnal and seasonal fluctuations in dissolved solids concentration are related to runoff characteristics and sources.
Revised Rb–Sr Age of the Lac du Bonnet Quartz Monzonite, southeastern Manitoba
Authors: Farquharson R. B.
Published: April 2011

New whole-rock Rb–Sr isotopic data from the Lac du Bonnet Quartz Monzonite pluton, combined with previously published analyses, yield an increased date for that pluton, the latest stage of major intrusion in this section of the Archean, English River Gneissic Belt. The age of the pluton and the associated metamorphism is revised from 2495 ± 180 m.y. to 2680 ± 91 m.y.