bluuebunny/crossref_metadata_2025 huggingface dataset:
Groundwater flow systems in the crystalline rocks of the Okanagan Highland, British Columbia
Authors: Lawson D. W.
Published: April 2011

An investigation of the groundwater flow systems associated with the most prominent topographic expression in the Okanagan Highland (a U-shaped valley) revealed that the hydraulic conductivity of the crystalline rock varies exponentially with depth, and that the local flow systems within the upper 125 to 150 ft of the crystalline rock conduct an estimated 10 to 17 Imperial gallons per day per foot thickness in a two-dimensional flow system. These local flow systems are quantitatively the most significant in the Okanagan Highland.
Electromagnetic damping of elastic waves: Experimental results
Authors: Lilley F. E. M. , Carmichael C. M.
Published: April 2011

The passage of an elastic wave causes straining and translation in the transmitting material. If a magnetic field is applied, and the medium is an electrical conductor, some of the energy of the wave is dissipated by the flow of electrical eddy currents. Usually the amount of energy lost is very small, but it may be greatly increased if the applied field is strongly non-uniform.Laboratory experiments are described which demonstrate this effect for standing elastic waves in a metal bar. The applied magnetic field changes from almost zero to its full strength over a distance which is short compared to the length of the standing wave. The result of this strong non-uniformity is that the energy lost due to the translation of the bar in the field greatly exceeds the energy lost due to the straining of the bar in the field.The dependence of the attenuation of the waves by the magnetic field is investigated for variation in frequency of vibration, bar thickness, and field gradient.
Holocene pollen assemblages from the Tiger Hills, Manitoba
Authors: Ritchie J. C. , Lichti-Federovich Sigrid
Published: April 2011

Coring of three kettle lakes in the moraine area known as the Tiger Hills, Manitoba, yielded sections of sediment which span the Holocene for this region. Detailed pollen analysis of two of the sections suggests five main pollen assemblage zones for the Holocene, numbered I to V from above. Zone V is interpreted as a spruce-dominated vegetation associated with such pioneering species as Shepherdia canadensis and Artemisia, a type found at present as local fragments and having no regional equivalent. Zone IV also has no analogue among recent pollen spectra, and is interpreted as a mosaic of mixed coniferous–broadleaved deciduous forest stands, and extensive scrub with Juniperus and grassland. Zone III is dominated by non-arboreal pollen types and suggests grassland, while Zone II has an oak component, which indicates a savanna type. Zone I is the modern assemblage, with prominent representation by weedy species. Radiocarbon age determinations suggest that the area was occupied by the Zone V assemblage from about 12 800 B.P.
Age of the northern part of the Nelson batholith
Authors: Nguyen K. K. , Sinclair A. J. , Libby W. G.
Published: April 2011

Nelson plutonic rocks in Slocan Mining Camp were emplaced at least 160 m.y. ago (base of the Upper Jurassic). K–Ar apparent ages for intrusions of lamprophyre and Valhalla plutonic rocks are indistinguishable from those for Nelson plutonic rocks. Younger apparent ages were obtained for altered samples and indicate at least one period of alteration less than 120 m.y. ago.
Abilities of explosion seismology in oceanic and continental crust and mantle studies
Authors: Kosminskaya I. P. , Zverev S. M.
Published: April 2011

Some physical parameters of explosion seismology are discussed, such as: the levels of useful explosion signals and microseisms and their spectra; resolving power of the Deep Seismic Sounding (DSS) method; models of the crust and the possibility of increasing the information which could be extracted from seismic records.
Geophysical and geological data in and around the Japan Arc
Authors: Rikitake T. , Miyamura S. , Tsubokawa I. , Murauchi S. , Uyeda S. , Kuno H. , Gorai M.
Published: April 2011

The geophysical and geological data in and near the Japan Arc are summarized as a contribution to the Upper Mantle Project. These up-to-date data presented here provide information about the structure and the physical processes underneath the islands of Japan, which are one of the typical island arcs. The following items are covered: topography and geology, volcanoes, gravity anomaly, earthquake seismology, explosion seismology, crustal thickness, crustal deformation, terrestrial heat flow, geomagnetic anomaly, and geomagnetic variation anomaly.
Structural features and some metallogenic patterns in the southern part of the Superior Province, Canada
Authors: Kalliokoski J.
Published: April 2011

In the southern part of the Superior Province of the Canadian Shield the Quetico belt of metasedimentary rocks extends northeasterly from Minnesota, across the Kapuskasing zone of crustal rifting, to southeast of James Bay. The belt forms part of a broader northeasterly-trending orogenic zone, and truncates the more westerly fold trends in the lavas and sedimentary rocks of eastern Ontario and western Quebec. It is suggested that the Quetico trend is the younger, and that the Quetico belt demarcates the geographic limits of the Kenoran orogen.In western Quebec and eastern Ontario three granite-cored massifs are bounded on their northern flanks by curved, regional faults and synclinal belts of metasedimentary rocks. The most important of these, the Pontiac Massif, is associated with a corresponding sediment-filled depression on the west.A broad region extending easterly and northeasterly from Lake Superior can be distinguished from contiguous areas on the basis of the abundance and extent of belts of iron-formation, many of these associated with acid volcanic rocks. It is proposed that these rocks were formed either in a restricted period of time or in a restricted volcanic-sedimentary environment.Massive, stratabound, pyritic base-metal sulfide ore deposits are most abundant in pre-Quetico rocks. They do not seem to be related to the processes associated with the deposition of abundant iron-formation.
Geochemistry and origin of metasediments in the Haliburton–Madoc area, southeastern Ontario
Authors: Kamp P. C. van de
Published: April 2011

Ortho- and para-amphibolites and related silicate and carbonate rocks in the Grenville Province in Ontario have been studied in the field and laboratory in order to determine their genesis. X-ray fluorescence chemical analyses for 31 elements in each of 100 rocks of similar types and of greenschist to granulite facies are used to show that the complex of metasediments was originally an association of tuffs and carbonates. The ortho-amphibolites probably are Na-metasomatized tholeiites. Para-amphibolites were basic tuffs; biotite-plagioclase gneisses were intermediate to acid tuffs. The tuffs were deposited in a region of carbonate sedimentation.Scapolite and clino-pyroxene are the dominant minerals in many of the granulite facies rocks. They are developed from decarbonated calcium-rich rocks to which chlorine was added. The average CO2 loss was 9 to 10 wt.%, and the average Cl addition was 0.8 wt.%. Zn and Pb probably were also added to the high-grade rocks.It is demonstrated that pelite-carbonate mixtures are unlikely progenitors of amphibolites but basic tuffs very likely are. Thin-layered amphibolites could easily be derived from basic tuffs such as occur in unmetamorphosed sedimentary sequences.
Heat flow and surface radioactivity in the Quirke Lake Syncline near Elliot Lake, Ontario, Canada
Authors: Sass J. H. , Killeen P. G. , Mustonen E. D.
Published: April 2011

Heat flow was measured in seven diamond-drilled holes, ranging in depth from 300 to 900 m, in the Quirke Lake Syncline (82° 30′ W, 46° 30′ N, mean elevation 370 m), Values for individual holes vary from 1.20 to 1.40 with a mean of 1.32 ± 0.02 μcal/cm2s, and no systematic variation was detected within the 50 km2 area studied. Radiometric measurements with a portable, three-channel, gamma-ray spectrometer show a downward concentration (stratigraphically) of Th, U, and K within the lower part of the syncline, with mean concentrations of 12.7 ppm, 3.3 ppm, and 1.9%, respectively. These data yield an average rate of heat production of 4.5 heat generation units (1 hgu = 10−13 cal/cm3s). Taking account of the ore zones, the mean heat production from the syncline is about 6 hgu. Corrections for structural effects and heat production from the ore result in a value of 1.2 for the regional heat flow. This is within the range of other shield values, although somewhat higher than the average for the Canadian Shield. The high value is readily explained if the observed mean surface radioactivity persists to a depth of 7 to 10 km.
The Wollaston Lake fold-belt system, Saskatchewan–Manitoba
Authors: Money P. L.
Published: April 2011

The Wollaston Lake fold-belt system, a major feature of the Churchill (structural) Province, consists of coalescing fold belts that collectively have been traced for about 400 miles. The fold belts, formed during the Hudsonian orogeny ~1750 million years ago, consist of tightly to isoclinally folded metamorphic and migmatitic rocks. They are bounded mainly by granitic rocks (in the broad sense) that are probably in part younger and in part older. The metamorphic rocks comprising them have been assigned locally to the Daly Lake, Sandfly Lake, or Meyers Lake Groups. The Daly Lake Group (a miogeosynclinal type of assemblage) has an uncertain relationship to the Sandfly Lake Group (eugeosynclinal assemblage); it was probably not deposited contemporaneously with the Meyers Lake Group. The Meyers Lake Group, which has a considerable resemblance to 'stable shelf1 assemblages, although it is less mature, overlies the Sandfly Lake Group, probably unconformably. Metamorphic rocks lithologically similar to those assigned to the Daly Lake Group form most of the fold-belt system. Rocks similar to those assigned to the other groups are of limited extent. The rocks within the fold-belt system have undergone regional metamorphism of the andalusite–sillimanite or low pressure intermediate type and in general now belong to the amphibolite facies. Mineralization within the fold-belt system, consisting of syngenetic (?) sphalerite, galena, and copper minerals, was widespread, but is not yet known to be of economic importance. The most prominent zone of magnetic anomalies in the Precambrian of Saskatchewan coincides in part with the fold-belt system.
Spectral analysis of vertical and horizontal earth current components at separated locations
Authors: Jones F. W. , Geldart L. P.
Published: April 2011

Comparisons of vertical and horizontal earth current components at separated locations have been made by comparing power density spectra of consecutive hourly intervals of data for continuous recording periods. The results indicate that both horizontal and vertical components are similar at separated locations, that the similarity in the dominant period improves at times of low-level geomagnetic activity, and that the vertical component at a location can have the same order of magnitude as the horizontal components.
Thermomagnetic properties of banded manganiferous sediment from the Mid-Atlantic Ridge
Authors: Schwarz E. J.
Published: April 2011

Banded manganiferous sediment from the Mid-Atlantic Ridge is paramagnetic at 20 °C and possibly has a Curie point at about −150 °C. Heating of the sediment in the range 520–560 °C prior to measuring probably results in the formation of a gradually changing ferrimagnetic spinel phase with a Curie point of 135 °C, which increases up to 180 °C. Heating to higher temperatures only results in a further increase in the relative abundance of the stable phase.
Timiskaming volcanism in the Kirkland Lake area, Ontario, Canada
Authors: Cooke D. L. , Moorhouse W. W.
Published: April 2011

The petrography and chemistry of the Timiskaming volcanics of the Kirkland Lake area reveal three distinct yet intimately associated suites within a composite volcanic-sedimentary sequence. The initial phase of Timiskaming volcanism was characterized by calc-alkaline lavas, which are transitional between the later alkaline volcanics of the Timiskaming and the underlying calcic Keewatin greenstones. Flows of alkalic mafic trachytes and a variety of leucitic lavas and pyroclastic rocks are the latest differentiates represented. This occurrence of leucitic volcanics is the first reported anywhere in the Precambrian. Deposition of sedimentary rocks and intrusions of syenite and mafic syenites were contemporaneous with the period of volcanism, but intrusions of feldspar porphyry were post-Timiskaming.The major mineral constituents are augite, biotite, plagioclase, leucite, and their alteration products. Potash feldspar and hornblende occur in subsidiary amounts, and magnetite and apatite are the common accessory minerals. The chemical composition of this volcanic sequence is marked by high alkalies, Al2O3, and low SiO2, P2O5, and TiO2. The calc-alkaline and alkaline lavas are rich in Na2O and poor in K2O and BaO, whereas the leucite lavas are high in K2O and BaO, and comparatively low in Na2O.The Kirkland Lake sequence is compared with similar exotic, but less altered, lavas of more recent age in order to clarify further the nature of Timiskaming volcanism. The alkalic association of the Kirkland Lake area is similar to those occurring at a late stage in the volcanic cycle of modern volcanic arcs and along orogenic belts marginal to major continental masses.
The system CaF2–CaMgSi2O6
Authors: Lin S. B. , Burley B. J.
Published: April 2011

The solid-melt equilibria of the system CaF2–CaMgSi2O6 (fluorite–diopside) have been studied at atmospheric pressure, using a modified quenching method. This system is characterized by a simple binary eutectic at CaF2 43.5, CaMgSi2O6 56.5 weight percent at 1082 ± 2 °C; neither solid solution nor intermediate compound was found. Certain of the skarns containing fluorite, diopside, and calcite in the Grenville Province of the Canadian Precambrian Shield are considered to have formed by differential melting of impure limestones in regional metamorphic terrains.
Ultramafic intrusions of the Abitibi area, Ontario
Authors: MacRae N. D.
Published: April 2011

A study has been made of the petrology and geochemistry of a 30-mile (48.3 km) segment of a belt of ultramafic-gabbroic igneous bodies extending past the south side of Lake Abitibi, Ontario. In general, the bodies are sill-like and are differentiated into major layers of peridotite, clinopyroxenite, and gabbro, the layers generally being in that stratigraphic order. In detail, the intrusions fall into four groups: (1) complex sills in which there is a cyclic repetition of layers; (2) simple differentiated sills showing only one sequence of the above rock layers; (3) bodies composed only of peridotite and dunite; and (4) bodies composed wholly of gabbroic rocks.One of the group (2) bodies has a chilled margin equivalent in composition to a tholeiitic basalt. The general structure of the intrusions and their petrographic and chemical features indicate that they are differentiated from basaltic magma by gravity-controlled fractionation. However, it appears that while solidifying, some of the intrusions were open to periodic addition or subtraction of magma. Thus, in the intrusions showing cyclic repetition of layers, it is apparent that the magma was altered prior to the formation of each cyclic unit such that the original order of mineral crystallization was repeated. For other intrusions, it can be inferred that large amounts of partly crystallized liquid were expelled such that each of these intrusions is now largely or wholly represented by ultramafic rocks. The bodies composed wholly of gabbro may be derived from the expelled magma.
Geometrical analysis of ripple-drift cross-lamination
Authors: Walker Roger G.
Published: April 2011

The geometrical parameters of ripple-drift cross-lamination (climbing ripples) have been measured in coastal exposures of the Cloridorme Formation (Middle Ordovician turbidites of northern Gaspé Peninsula, Québec), in order to determine the factors that control the angle at which the ripples climb, and to investigate the context of the ripple-drift relative to the other sedimentary features in the Cloridorme Formation. Purely geometrical analysis shows that the angle of the stoss side is more sensitive in controlling the angle of climb than the angle of the lee side, but the single most important factor is the ratio of thickness of the stoss side and lee side laminae. When the lee laminae are about twice as thick as the stoss laminae, the angle of climb is about 30–40 degrees. If the ratio is greater than about 10, the angle of climb is reduced to about 5 degrees.The lamina thicknesses are controlled by the rate of deposition from suspension relative to the rate of bed load movement. At high flow regimes, sediment is swept onto the lee side and the angle of climb is low. In the Cloridorme Formation, the turbidites associated with the ripple-drift are proximal, and hence a rapid flattening of the basin floor gradient is suggested to cause the rapid deposition leading to ripple-drift formation.
Groundwater–streamflow systems in Wilson Creek Experimental Watershed, Manitoba
Authors: Newbury R. W. , Cherry J. A. , Cox R. A.
Published: April 2011

Preliminary studies of the groundwater–streamflow systems in the Wilson Creek Watershed in south-western Manitoba indicate that the hydrochemical characteristics of the system may be used to: (1) identify the base flow component of storm runoff hydrographs; and (2) determine what proportions of the base flow are derived from in-basin and out-of-basin recharge areas.
Nepheline gneisses of the Wolfe Belt, Lyndoch Township, Ontario. II. Textures and mineral paragenesis
Authors: Appleyard Edward C.
Published: April 2011

The nepheline-bearing gneisses of the Wolfe Belt in Lyndoch Township, Ontario, have been subjected to textural, fabric, and paragenetic analysis on the basis that they are metamorphic tectonites. In addition, information has been drawn together from various sources bearing upon the relative chronology of Plutonic events, principally metamorphic, diastrophic, and intrusive, of the Grenville orogeny.The alkaline character of the nepheline gneisses has been confirmed as syn-orogenic in origin, apparently forming under upper amphibolite-facies metamorphic conditions during a static interval prior to the second of three recognizable periods of folding. The original 'replacement' textures were largely erased by a penetrative recrystallization during the second period of folding. The Wolfe gneisses principally reflect in their parageneses and textures this metamorphic event. Some textural criteria previously considered to have genetic significance in the origin of the alkaline rocks date from this recrystallization or even later crystalloblastic events. The problem of regional scapolitization is briefly considered. Petrofabric and geological evidence suggest the scapolite developed prior to or early in the third phase of folding.A synthesis of events in the Grenville orogeny as indicated by these rocks is attempted.
Balanced cross sections
Authors: Dahlstrom C. D. A.
Published: April 2011

Post-depositional concentric deformation produces no significant change in rock volume. Since bed thickness remains constant in concentric deformation, the surface area of a bed and its length in a cross-sectional plane must also remain constant. Under these conditions, a simple test of the geometric validity of a cross section is to measure bed lengths at several horizons between reference lines located on the axial planes of major synclines or other areas of no interbed slip. These bed lengths must be consistent unless a discontinuity, like a décollement, intervenes. Consistency of bed length also requires consistency of shortening, whether by folding and (or) faulting, within one cross section and between adjacent cross sections.The number of possible cross-sectional explanations of a set of data is reduced by the fact that, in a specific geological environment, there is only a limited suite of structures which can exist. This imposes a set of local "ground rules" on interpretation. When these local restrictions are coupled with the geometric restrictions which follow from the law of conservation of volume, it is often possible to produce structural cross sections that have a better-than-normal chance of being right.The concept of consistency of shortening can be extrapolated to a mountain belt as a whole, thereby indicating the necessity for some kind of transfer mechanism wherein waning faults or folds are compensated by waxing en echelon features. These concepts are illustrated diagrammatically and by examples from the Alberta Foothills.
What are glacier surges?
Authors: Meier Mark F. , Post Austin
Published: April 2011

A total of 204 surging glaciers has been identified in western North America. These glaciers surge repeatedly and probably with uniform periods (from about 15 to greater than 100 years). Ice flow rates during the active phase may range from about 150 m/year to > 6 km/year, and horizontal displacements may range from < 1 to > 11 km. Ice reservoir and ice receiving areas can be defined for surging glaciers, and the reservoir area does not necessarily coincide with the accumulation area. Glaciers of all shapes, sizes, and longitudinal profiles can surge, and no unusual "ice dams" or bedrock constrictions are evident. Surges occur in many different climatic, tectonic, and geologic environments, but only in certain limited areas (mainly in the Alaska, eastern Wrangell, and St. Elias mountains). Three types of surging glaciers are defined: (I) large to moderate-sized glaciers with large displacements and very fast flow, (II) large to moderate glaciers with moderate displacements and flow rates, and (III) small glaciers with small displacements and moderate to fast flow rates. All three types involve an inherent instability which is self-triggered at regular intervals, but with Type I surges an additional (unknown) mechanism produces the very high flow rates.
Observations of the surge of Steele Glacier, Yukon Territory, Canada
Authors: Stanley A. D.
Published: April 2011

For part of 1966, Steele Glacier in the Icefield Ranges, Yukon Territory, Canada, made a spectacular advance at a rate exceeding 500 m per month. The main part of the surge continued for two years, but by early 1968 the advance had slowed to less than one tenth of the maximum rate. For most of the 35-km length of the main trunk the surface was a chaotic jumble of ice blocks, spires, and pinnacles, but large structures outlined by surface moraine were preserved. Most of these structures had been displaced 8 km by August 1967, irrespective of their original location. Preliminary measurements indicate structures were displaced similar distances down the length of the glacier and suggest that most of the glacier moved forward as a block. The surge has not been correlated with any local earthquake activity, and there is no evidence for a short-term climatic change. The movement is considered to result from critical dynamic conditions within the glacier, possibly facilitated by increased amounts of water along the ice-bedrock contact.
Some comments on glacier surges in eastern Svalbard
Authors: Schytt V.
Published: April 2011

Between 1936 and 1938 a great amount of ice flowed out from Sörfonna (the South Ice) on the south coast of Nordaustlandet. What had been an even slope of the ice sheet in 1936 developed into a badly crevassed glacier tongue by 1938, pushing approximately 20 km out to the sea along a front of 30 km. The new glacier was named Bråsvellbreen, which in fact means "rapid growth glacier", but because of World War II, no field investigations could be carried out until more than 10 years after its discovery.The majority of glaciers in eastern Vestspitsbergen have retreated during this century—a few, however, have advanced considerably during short periods and taken part in the general retreat during the rest of the time.Air photographs from 1924, 1938, 1956, and 1957 show that most of the ice edge in western Nordaustlandet has remained stable—Söre Franklinbreen, however, has shown large oscillations.The glaciers in the area belong to the sub-polar type, i.e. the 10-m ice temperature in the ablation area remains at about 8–10° below zero throughout the year, whereas the 10-m firn temperature in the accumulation area is at or very near freezing point.There are large variations in accumulation conditions from one Spitsbergen glacier to the other. The west coast of Vestspitsbergen is under the influence of mild and wet air masses from the Atlantic—the east coast is far more continental. The Nordaustlandet ice caps, on the other hand, receive most of their accumulation with winds from the Barents Sea. Annual net balance values of 80–120 g/cm2 are quite common on the eastern slopes of Austfonna (the East Ice), values of 70–90 g/cm2 have been observed along the crest of Sörfonna, and it is likely that large parts of the accumulation area of Bråsvellbreen itself receives an annual net balance of between 50 and 90 g/cm2.
Glacier surges in Iceland, with special reference to the surges of Brúarjökull
Authors: Thorarinsson Sigurdur
Published: April 2011

The glacier surges that have occurred in Iceland since 1890 are listed, and the largest ones, those of Brúarjökull in 1890 and 1963–64, are described. The glacier area affected by the surges of Brúarjökull is about 1400 km2, the volume of ice and firn affected is about 700 km3, and the total advance of the glacier front is 8–10 km. The maximum rate of advance of the glacier front in 1963 was at least 5 m/hour. Brúarjökull's surges seem to occur with an interval of 70–100 years.
Glacial activity preceding the 1956 Muldrow Glacier surge in Alaska
Authors: Harrison A. E.
Published: April 2011

Photographic evidence suggests that a normal wave of ice was progressing down the Muldrow Glacier prior to the occurrence of the surge in 1956. The ice thickening began before 1947, with a wave motion of about 250 m per year between 1948 and 1952. Progress may have slowed after 1952 because the bulging lateral margin had not reached the McGonagall Pass by 1954. The ice opposite McGonagall Pass thickened spectacularly after 1954 and a lateral ice cliff extended at least 1.6 km beyond McGonagall Pass when the ice began its surge movement in 1956. Aerial photographs taken after the surge ended in 1957, plus photographs from the ground in the vicinity of the bend in the Muldrow before surge motion reached that area in 1956, suggest that several small tributaries were also rejuvenated just before the surge occurred. These observations point to the possibility of climatic synchronism in the Alaskan Range and the southern ranges of North America.
The geology and geochronology of the Makkovik Bay area, Labrador
Authors: Gandhi S. S. , Grasty R. L. , Grieve R. A. F.
Published: April 2011

The sedimentary and volcanic formations of the Aillik series in the Makkovik Bay area of the Labrador coast are about 25 000 ft (~7620 m) in thickness. They have been folded into a series of northerly-trending folds and are intruded by gabbro, diorite, syenite, and abundant granite. Potassium–argon age determinations range from 1730 to 1830 million years for two gneisses, and from 1500 to 1600 million years for the metamorphosed sedimentary and volcanic rocks and intrusive granite-gneiss and granite. The structural features of the area indicate a single cycle of orogenic deformation for the sedimentary and volcanic rocks, in which the emplacement of synkinematic granite gneiss as domes and other bodies played an important role. One of the gneisses is considered a part of the migmatized Archean basement on which the Aillik series was laid down, and was subsequently involved in the Hudsonian orogenic cycle about 1600 million years ago. The area lies to the northwest of the Grenville Front, and has been intruded by diabase dikes corresponding in age to the Grenville orogeny, and by lamprophyre dikes of Cambrian age.
Incremental stress under a two-dimensional artificial lake
Authors: Gough D. I.
Published: April 2011

Seismic activity has been induced by loading and possibly lubrication of faults in rocks underlying several artificial lakes. Such evidence of failure justifies study of incremental stress distributions produced by the filling of artificial lakes. In this paper two-dimensional lakes are considered. Equations are derived giving the incremental stress components due to a side of a water-filled trough of polygonal section in the surface of art elastic half-space. A computer program based on these equations is described. Distributions of stress parameters are shown for lakes of rectangular and isosceles triangular sections, and for a two-dimensional approximation of a section of the lake forming behind the Bennett Dam on the Peace River, British Columbia.
Pleistocene grayling, Thymallus, from Yukon, Canada
Authors: McAllister D. E. , Harington C. R.
Published: April 2011

Eleven cycloid fish scales or scale fragments with scalloped anterior margins were obtained from a Pleistocene deposit in the Old Crow area, Yukon Territory. Shells from the same horizon as the scales were radiocarbon dated at 32 400 ± 770 yr B.P. The scales are from the Arctic grayling, Thymallus arcticus, providing the first fossil records of the genus and of the subfamily Thymallinae for North America.
Feldspars from Adamant pluton, British Columbia
Authors: Fox Peter E. , Moore Jr. John M.
Published: April 2011

Adamant pluton is a zoned body of igneous origin, with a core of pyroxene monzonite transitional outward to hornblende quartz monzonite and biotite-hornblende granodiorite. On chemical and textural evidence, the lithologic zoning resulted from reaction with introduced water and oxygen during regional metamorphism to upper amphibolite facies. Feldspars in the monzonite are orthoclase and andesine of intermediate structural state. During transformation of the pluton, systematic changes in the feldspars comprised: (1) ordering of alkali feldspars toward intermediate microcline, with increase of 2V, decrease of Na and Ca content, and appearance of grid twins; (2) ordering and increase in Na content of plagioclase. The most ordered feldspars, with highest Na distribution coefficient, are found in peripheral granodiorite and in pegmatite cutting the quartz monzonite. The feldspar data support the model proposed for the evolution of the pluton, indicating approach to equilibrium in the peripheral rocks at lower temperatures than that attendant to the formation of the core.
Evidence for the residual character of two soils, one on granite, the other on limestone in Peterborough County, Ontario
Authors: Gillespie J. E. , Protz R.
Published: April 2011

The morphology, particle size distribution, and clay mineralogy data of a Methuen soil derived from a granite and a Tweed soil derived from a crystalline limestone are interpreted as supporting the concept that these two soils are residual. Sand mineralogy and elemental analysis of mica support the residual hypothesis.
A map of Rayleigh-wave dispersion in the Pacific
Authors: Savage J. C. , White W. R. H.
Published: April 2011

The group velocity vs. frequency curves for 103 different Pacific paths have been analyzed to determine the group velocity dispersion as a function of latitude and longitude in the neighborhood of the group velocity maximum. The main features of the local group velocity dispersion curves can be specified by the maximum group velocity u0, the period t0 at which the maximum occurs, and a factor b related to the curvature of the dispersion curve at its maximum. The highest group velocities are found in the northwest Pacific where u0 exceeds 4.2 km/s. The Andesite line appears as a region of rapid change in u0, t0, and b. The East Pacific Rise is not delimited by the dispersion map, but it occurs in a region of low u0, t0, and b. The principal value of the maps appears to be that they present qualitative information on the crust and upper mantle structure.
The coast-parallel dike swarm of southwest Greenland in relation to the opening of the Labrador Sea
Authors: Watt W. Stuart
Published: April 2011

Coast-parallel gabbro dikes in southwest Greenland have been dated as Jurassic; their distribution and age suggest that initial rifting between Greenland and Labrador took place at about the middle of the Mesozoic Era.
An alkaline rock province linking Europe and North America
Authors: Doig Ronald
Published: April 2011

Lower Paleozoic carbonatites associated with the St. Lawrence graben system are correlated with carbonatites of similar age (565 m.y.) in Greenland and Scandinavia. The correlation is well established in Canada where the intrusions all occur along a continuous rift system. The reconstruction of the whole province is made possible by restoring the continents to the positions they occupied prior to their separation.The combination of unique petrologic character, age, and structural setting shows that these rocks belong to a single alkaline rock province, defined by a rift system extending at least from central Canada to eastern Sweden that was active throughout its length about 565 m.y. ago.Periodic intrusion of alkaline rocks has occurred later, on both continents, associated with the components of the fracture system. In eastern Canada, alkaline rocks occur locally with ages of 520, 450, 300, and 110 m.y. in addition to the widespread 565 m.y. event.
The Precambrian geochronology of Rajasthan and Bundelkhand, northern India
Authors: Crawford A. R.
Published: April 2011

Many new age determinations are reported for the Precambrian of Rajasthan and Bundelkhand in northern peninsular India. All are by Rb–Sr and mostly from total-rock analyses. They show that the oldest rocks in the area are undated sediments intruded by the Bundelkhand and Berach Granites, dated at about 2550 m.y. The overlying Aravalli System was intruded by granites dated at between 1900 and 2100 m.y., and is succeeded by the Delhi System, which was intruded by granite dated at 1650 m.y. Other granitic intrusion at 950–1000 m.y. was followed by repeated pegmatitic intrusion. The Banded Gneiss Complex of Rajasthan contains components of ages varying from at least 2000 m.y. to less than 1000 m.y. Nepheline-syenites at Kishangarh have an age of 1490 ± 150 m.y., but a biotite in an inclusion gives 970 m.y., which is the age of the Newania carbonatite.These determinations show that the Precambrian sequence in Rajasthan is much older than previously suggested. They confirm the antiquity of the Bundelkhand–Berach craton suggested by field studies, denying its derivation from Aravalli System rocks by granitization.
Cretaceous strata on the Scotian Shelf
Authors: King Lewis H. , MacLean B. , Bartlett Grant A. , Jeletzky J. A. , Hopkins Jr. William S.
Published: April 2011

Samples of Cretaceous sediment have been dredged from the Scotian Shelf at a locality 100 km north-northwest of Sable Island.Continuous seismic-reflection profiles across the sample area show the presence of well defined stratification within the bedrock. These beds are truncated by the slopes of submarine valleys which transect the area. Bedrock appears to outcrop along the upper portion of the valley walls or be covered by a layer of unconsolidated material so thin as to be beyond the resolution of the seismic equipment. The dredged material appears to have come from rubble heaps near the base of the valley slopes and is believed to have originated locally.Approximately 450 kg of sedimentary rock were recovered consisting principally of sideritic quartz sandstone and arenaceous sideritic carbonate, both with fossiliferous material. Glauconite is a significant constituent of many samples.The macrofauna include sufficiently diagnostic forms to suggest correlation with the early Upper Cretaceous (Cenomanian) though the possible presence of older or younger forms cannot be wholly excluded. The microflora and microfauna appear to correlate mainly with the Albian-Aptian, and Albian-Cenomanian, respectively.Cretaceous strata immediately underlie much of the central and eastern portions of the Scotian Shelf. Tertiary sediments reported by Marlowe and Bartlett overlie the Cretaceous toward the continental margin and appear to occur as a discontinuous veneer at other localities on the shelf.
Chemical petrology of some pelitic gneisses and migmatites from the Thor-Odin area, British Columbia
Authors: Froese E.
Published: April 2011

The Shuswap metamorphic terrain of British Columbia is marked by the occurrence of gneiss domes, one of these in the Thor-Odin area. In this case, a core of migmatites and granitoid gneisses is surrounded by a mantle of unmigmatized gneisses. Rocks of both structural zones belong to the sillimanite – almandine – orthoclase subfacies of the almandine–amphibolite facies. A common mineral assemblage in pelitic gneisses and migmatites is quartz + plagioclase + K feldspar + biotite + garnet + sillimanite. These minerals are related by the reaction[Formula: see text]This reaction is used as a measure of [Formula: see text] conditions. Variations of biotite and garnet composition from rock to rock indicate differences in [Formula: see text] conditions of quenching. Furthermore, according to the ranges in composition, the migmatites from the core zone reflect either a higher [Formula: see text] at constant T or a lower T at constant [Formula: see text] than the mantling gneisses. Assuming that [Formula: see text] is approximately equal to Ptotal during metamorphism of pelitic rocks, the second case is more probable. The [Formula: see text] values, rather than representing peak metamorphic conditions, are attributed to quenching during cooling when no more water is available. A higher water content in the core rocks might account for migmatization as well as for a somewhat lower quench temperature.
The Paint Pots, Kootenay National Park, British Columbia—acid spring water with extreme heavy-metal content
Authors: Everdingen R. O. van
Published: April 2011

The Paint Pots, a group of mineral springs in Kootenay National Park, British Columbia, produce acid water (pH = 2.5 to 3.5) with a high content of Fe, Zn, Mn, and Pb, derived from sulfide mineralization in the Cambrian rocks of the area. Oxidation of the Fe++ in the water and hydrolysis of the resulting Fe+++ produce a still lower pH in the water, a high redox potential, and a deposit of ferric (oxy) hydroxide. Less than half the available iron, approximately three-quarters of the manganese and zinc, and most of the lead are discharged into the Vermilion River. The strong dilution provided by the high flow rate of the Vermilion River prevents any serious pollution. A simple laboratory test shows that circulation of the acid spring water through crushed limestone will remove all the iron, introduce some oxygen, and reduce both the acidity and the redox potential to normal surface water values. Zinc, manganese, and lead are probably removed incompletely.
A geological interpretation of gravity and magnetic data, northwest Saskatchewan
Authors: Wallis R. H.
Published: April 2011

The striking 'fit' of aeromagnetic and gravity data from the Precambrian of northwest Saskatchewan, combined with known and nearby analogous, geological relationships, suggests the presence of a northeast-trending belt, 250 × 20 miles (400 × 30 km), of early Proterozoic (?) metasedimentary rocks, probably magnetite-bearing meta-arkoses. This structural–sedimentary unit might have economic possibilities analogous to other northeast-striking, Precambrian, lower Proterozoic (?), metasedimentary belts of northern Saskatchewan, the Virgin River Belt, and the Wollaston Trend.
Groundwater movement in a glacial complex, Cochrane district, Ontario
Authors: Parsons Myles L.
Published: April 2011

Groundwater flow is examined in a glacial geologic environment thought to be typical of the Clay Belt of northern Ontario. The geologic framework comprises two eskerine sand bodies separated and partially covered by an extensive plain of lacustrine clay, all underlain by discontinuous till resting on fractured crystalline bedrock. The groundwater flow medium is characterized by large hydraulic conductivity variations ranging over at least four orders of magnitude. Consequently, two distinctive types of groundwater environment are recognized: the esker environments consisting of elongated linear bodies of very permeable sand and gravel, and the clay plain environment characterized by a clay-over-till layered medium of relatively low permeability.Piezometric head measurements are interpreted with the aid of a numerical model of the potential field, obtained as a solution to the differential equation of steady-state groundwater flow. Three types of groundwater flow systems are distinguished: local flow systems associated with the topographically high eskers, local flow systems of limited lateral extent centered around the entrenched valleys in the clay plain, and regional flow systems with recharge in the flat interstream clay plain areas extending into the bedrock.
On the geology and geochronology of northwestern Saskatchewan. I. Tazin lake region
Authors: Koster F. , Baadsgaard H.
Published: April 2011

The rocks of the Tazin Lake region, north of Lake Athabasca, have been subdivided into three major complexes: the Northeastern basement complex, mainly composed of a syn-to-late tectonic granodiorite-diorite series; a central meta-sedimentary and gneissic belt; and the Western granodiorite complex. Mylonitization, folding, and faulting are common in the centrally located meta-sedimentary and gneissic belt. Twenty new radiometric age determinations by the K–Ar method on biotite and amphibole of the granodiorite–diorite series average 2370 ± 40 m.y. Fragmentation of late tectonic basic dikes and remobilization of the granodiorite–diorite series have been provisionally correlated with this established minimum age. The Western granodiorite complex was intruded 1900 m.y. ago. One biotite sample from White Lake granite of the meta-sedimentary and gneissic belt indicates an apparent K–Ar age of 1800 m.y.
Thermal conductivity of frozen soils
Authors: Penner E.
Published: April 2011

Thermal conductivity measurements of two frozen soils, Leda clay and Sudbury silty clay, taken at temperatures between 0 and −22 °C by means of a thermal probe and a transient heat flow technique, compare favorably with estimates of thermal conductivity calculated by the DeVries method. Both measured and estimated values show a similar trend of increasing thermal conductivity as the temperature is lowered and the ice content grows. This increase is associated with the higher thermal conductivity of ice compared with that of water.
Sur les Umbellaceae
Authors: Mamet Bernard L.
Published: April 2011

The presence of an apical lid is recognized among Devonian Umbellids of Alberta. Their attribution to the Paleozoic foraminfers is therefore unwarranted and their transfer to the charophytes is suggested. The taxonomy of the family is revised and three new genera are proposed.
Neoglacial fluctuations of the Natazhat and Klutlan Glaciers, Yukon Territory, Canada
Authors: Rampton Vern
Published: April 2011

The Natazhat and Klutlan Glaciers are surging valley glaciers whose present termini are located at the northern edge of the St. Elias Mountains. Both glaciers have massive ice-cored Neoglacial morainal complexes extending down-valley from their ice termini. At least six separate Neoglacial moraines adjacent the Klutlan Glacier and four adjacent the Natazhat Glacier have been identified from changes in the geomorphic, pedologic, limnologic, vegetational, dendrochronologic, and lichenometric characteristics across the morainal complexes. Dating of the individual moraines by lichenometry, dendrochronology, and 14C implies that most were constructed within the last 550 years, although both glaciers have been relatively inactive near their termini since 1947.Stratigraphy and 14C dates suggest that the initial Neoglacial advance of the Natazhat Glacier near its Neoglacial maximum occurred ca. 3300 B.P. and that of the Klutlan Glacier ca. 1520 B.P.Intervals during which the glaciers constructed a number of moraines near their Neoglacial maxima probably were caused by cool summer temperatures, even though individual moraines were formed by glacial surges. A number of factors make impossible precise dating of the intervals of cool summer temperatures.
The ABC Fault, Beaverlodge, Saskatchewan
Authors: Beecham A. W.
Published: April 2011

Three prominent faults cut the complexly-deformed rocks of the Beaverlodge area, Saskatchewan. These are the Black Bay, the St. Louis, and the ABC Faults. The Black Bay strikes northeast and dips to the southeast. The St. Louis, with a similar attitude, lies a few miles southeast of the Black Bay and, as traced southwestward, bends gradually toward the other fault. At a point where the two faults are about 3.5 miles (5.5 km) apart, a third fault runs between these two breaks. This third fault, the ABC, strikes northwest and dips southwest.A study of major and minor fractures along the ABC Fault indicates a left-hand, normal oblique movement for the fault. This evidence combined with the stratigraphic separation of the Martin Formation across the fault, gives a net slip for the ABC Fault of 12 × 103 ft (3.7 × 103 m). The southwest side moved down and southeastward relative to the northeast side.Movements on faults in the area imply two main orientations of principal stresses. These orientations apparently occurred at different stages in the uplift of a northeast-southwest elongated dome.
Electromagnetic damping of elastic waves: a simple theory
Authors: Lilley F. E. M. , Carmichael C. M.
Published: April 2011

An order-of-magnitude estimate is made to check the effect observed in previously described experiments in which vibrations in a metal bar were damped by an applied magnetic field that was strongly non-uniform. Though the awkward geometry of the experiment has prevented an accurate analytical solution of the problem, some reasonable assumptions allow a simple expression for the effect to be obtained directly. This expression is in agreement with the experimental results regarding the dependence of the effect upon frequency, bar dimensions, density, electrical conductivity, and magnetic field gradient.