bluuebunny/crossref_metadata_2025 huggingface dataset:
A coring and squeezing technique for the detailed study of subsurface water chemistry
Authors: Patterson R. J. , Frape S. K. , Dykes L. S. , McLeod R. A.
Published: April 2011

A coring and squeezing technique has been modified and simplified to permit the collection of closely spaced samples of pore water from both the saturated and unsaturated zones on land, and bottom sediments in lakes and rivers. Samples of the pore water are obtained by placing short sections of sediment from freshly collected cores in a mechanical squeezer and applying pressure to extrude the contained fluid into a syringe. If coarse incompressible sediments are encountered, the pore water is removed by an immiscible-fluid displacement technique. The pore water samples are analyzed by standard methods for major and minor components. Also, in situ measurements of some parameters are carried out by directly inserting electrodes into the fresh sediment. These methods are being applied at a number of locations in southern Ontario to study the quality of waters in the unsaturated zone, the chemistry of natural and contaminated groundwaters, and the significance of seepage and baseflow in lakes and rivers respectively.
Rb–Sr ages of silicic igneous rocks and deformation, Burlington Peninsula, Newfoundland
Authors: Pringle Ian R.
Published: April 2011

The Burlington Peninsula, east of the Baie Verte Lineament, is underlain by the Eastern Division of the Fleur de Lys Supergroup, a sequence of metasediments and metavolcanic rocks that is intruded by plutonic masses of granitic to granodioritic composition. This sequence has been designated as Cambrian or older and the deformation and metamorphism in the area interpreted as pre-Ordovician. Recently, however, it has been shown that at least part of the succession is post Lower Ordovician and a mid or late Palaeozoic age has been proposed for the major deformation affecting the area.Rb–Sr ages obtained in the present study area are: (a) whole-rock isochrons—Dunamagon Granite, 413 ± 10 Ma; Cape Brulé Porphyry, 393 ± 25 Ma; Cape St. John Group Ignimbrites, 343 ± 15 Ma and 429 ± 50 Ma; Mic Mac Group Ignimbrite, 375 ± 15 Ma; (b) Biotite ages—Dunamagon Granite, 334, 356 and 358 Ma; (c) Mineral isochron—Burlington Granodiorite, 422 ± 40 Ma. Because of extensive trace element migration in at least some of these units, the interpretation of the ages is complex and does not allow a unique history of the area to be determined. However, the ages do support the proposed mid or late Palaeozoic age for the major deformation and indicate that pre-Ordovician orogeny did not prevail on the scale previously envisaged.
The glacial geology of northeastern Ellesmere Island, N.W.T., Canada
Authors: England John
Published: April 2011

Thirty-five radiocarbon dates associated with former ice sheet margins and raised marine deposits are presented from northeastern Ellesmere Island. Along the southern margin of Hazen Plateau, and in inner Archer Fiord, a prominent morpho-stratigraphic boundary is marked by the Hazen Moraines. These moraines represent a restricted ice advance during the last glaciation and date ca. 8130 ± 200 BP. On the immediate distal side of the Hazen Moraines, eastward for 100 km towards northwestern Greenland, the majority of dates on marine limits show synchronous emergence beginning ca. 7500 BP. This zone of synchronous emergence is considered to represent an ice-free corridor isostatically unloaded between the margins of the receding Greenland and Ellesmere island ice sheets.A more widespread till, above and beyond the Hazen Moraines, extends out of Archer Fiord–Lady Franklin Bay to Robeson and Kennedy channels. This maximum ice advance is considered to predate the last glaciation on the basis of 14C and amino acid dates from ice-marginal deposits; however, alternative interpretations of the data are presented. Previous evidence suggesting an older advance of the Greenland Ice Sheet onto this coastline is confirmed. Several glaciers in the area are presently at their maximum postglacial positions.
A re-investigation of the orientation of quartz in a shear zone from Castell Odair, Scotland
Authors: Starkey John , Sutherland Ian
Published: April 2011

The orientation of quartz c-axes has been determined in a shear zone developed in amphibolitized metagabbro. Contrary to previously published data the quartz shows no preferred cyrstallographic orientation. This study underlines the importance of proper sample selection when collecting orientation data.
Emplacement of Archean peridotitic komatiites in La Motte Township, Quebec
Authors: Lajoie Jean , Gélinas Léopold
Published: April 2011

Field evidence suggests that the contact between the A and B divisions of the peridotitic komatiites, exposed at Spinifex Ridge, La Motte Township, Quebec, is erosional. The B division commonly shows parallel and (or) oblique layering which may occur in sequences. Reverse grading of hopper olivine crystals is observed at the top of the B division, whereas the underlying more equant, solid olivine crystals may be normally graded. These observations suggest that, for the La Motte komatiites, the spinifex (A) division formed first causing a diminution of the hydraulic radius of the conduit, leading to an increased velocity and turbulent underflow that produced the structures observed in the B division.
Eohiodon woodruffi n. sp. (Teleostei, Hiodontidae), from the Middle Eocene Klondike Mountain Formation near Republic, Washington
Authors: Wilson Mark V. H.
Published: April 2011

The new species Eohiodon woodruffi is the second known species of the fossil hiodontid genus Eohiodon. It occurs in Middle Eocene freshwater tuffaceous shales of the lower Tom Thumb Tuff Member and the Middle Member of the Klondike Mountain Formation, near Republic, Washington. The new species differs from Eohiodon rosei in having more anal fin rays and in being deeper bodied. Eohiodon woodruffi also occurs with Eohiodon rosei in Eocene sediments near Horsefly, British Columbia.
The sulfur content of Archean volcanic rocks and a comparison with ocean floor basalts
Authors: Naldrett A. J. , Goodwin A. M. , Fisher T. L. , Ridler R. H.
Published: April 2011

In this paper we report the sulfur contents of 1056 basalts, andesites, dacites and rhyolites of known major element composition from the Rankin–Ennadai, Birch Lake – Uchi Lake, Lake of the Woods – Wabigoon Lake, Timmins and Skead Archean greenstone belts of the Canadian Shield. The sulfur contents of 299 ocean floor basalts and 68 sub-aerial or shallow water extrusive rocks are also reported. Sulfur contents for rocks of a given class are highly variable, ranging from near zero to several thousand parts per million (ppm). However, when averages for each of the rock classes are examined, the data from the two best documented of the Archean greenstone belts exhibit the same positive correlation between sulfur and total Fe content of the rocks. The trend for the Rankin–Ennadai belt coincides almost exactly with that reported earlier for the Blake River Group, approximating that expected if the rocks were saturated in sulfide at the time of extrusion. Rocks from the Lake of the Woods – Wabigoon Lake, Timmins and Skead areas seem to be somewhat poorer in sulfur than those from the Rankin–Ennadai and Blake River belts.Despite the fact that all evidence in the literature for fresh glassy pillow rims indicates that modern ocean floor basalts are saturated in sulfide, our average values for these ocean floor rocks are much lower than the predicted saturation levels, suggesting that the rocks have lost one-half to three-fourths of their sulfur, presumably through reaction with sea water. It is suggested that the reason for the Archean basalts retaining most of their sulfur despite the extensive redistribution that has occurred, whereas modern ocean floor basalts lose so much, may be due to the Archean rocks accumulating much more quickly and being exposed to direct interaction with sea water for a much shorter time than the modern rocks.
A demonstration of the interdependence of the degree of quartz preferred orientation and the quartz content of deformed rocks
Authors: Starkey John , Cutforth Carol
Published: April 2011

The orientation of quartz c-axes has been determined from mineralogically distinct layers of several metamorphic rocks. Individual specimens were chosen for which the external conditions of deformation could be assumed to be constant, the only significant variation within a specimen being in mineralogical composition. Conversely, the suite of specimens was chosen to represent a range in temperature, pressure, stress, finite strain and strain rate; the different orientation patterns that were observed demonstrate the operation of different, dominant orienting mechanisms. A detailed analysis of these specimens reveals a linear correlation between quartz content and the degree of preferred orientation of the quartz; the orientation pattern approaches random as the quartz content approaches zero. No correlation between degree of preferred orientation and any other parameter was found.It is concluded that the dispersion of the patterns of preferred orientation resulted from grain boundary sliding between the quartz and matrix.
The petrochemistry and geologic implications of conglomerates from Archaean geosynclinal piles of southern India
Authors: Naqvi S. M. , Rao V. Divakara , Hussain S. M. , Narayana B. L. , Rogers John J. W. , Satyanarayana K.
Published: April 2011

Conglomerates are abundant in the 2.6 Ga old geosynclinal piles of southern Peninsular India and some also occur in the 3.4–3.2 Ga old greenstone belts. The conglomerates in the greenstone belts are autoclastic or pyroclastic, in contrast to the conglomerates in the geosynclinal piles, which generally contain graywackes indicative of sedimentation by turbidity currents.Analyses of 104 pebbles and 28 matrices from the 2.6 Ga-old conglomerates and petrological data show that their source areas were made up of basic–ultrabasic volcanics, trondhjemitic–tonalitic acid plutonics, and phyllite–amphibolite–quartzite–chert–ironstone metasediments. The variations in the composition of the trondhjemite–tonalite pebbles from the Shimoga, Bababudan, Chitradurga, and Gadag geosynclinal piles indicate the significant overall low abundance and differences in the availability of free plutonic quartz for sedimentation. The abundance of Na2O in the matrices and associated graywackes may be due to the high Na2O content of detrital plagioclase fragments derived from trondhjemites and tonalites. The Na2O contents of Archaean graywackes do not appear to be a result of post-depositional albitization of plagioclase. The scarcity of K-rich pebbles, and the K-depleted nature of most of the matrices, indicate that the earlier acid plutonic rocks associated with the true greenstone belts were mainly trondhjemitic–tonalitic in character, and K-rich acid plutonism was largely a post-geosynclinal development. The plutonic source terranes of the geosynclinal piles are similar in some aspects to those of much younger geosynclines throughout the world.
Huronian polar wander and paleomagnetism of the Thessalon volcanics
Authors: Symons D. T. A. , O'Leary R. J.
Published: April 2011

The Thessalon basalts outcrop in Ontario on the north shore of Lake Huron near the base of the Huronian Supergroup in the Southern tectonic province. After alternating field and thermal demagnetization on 230 specimens from 23 sites, a stable high coercivity remanence in titanomagnetite was isolated giving a direction of 304°, 54° (α95 −7°). The pole position of 169°W, 47°N (7°, 9°) corresponds to the primary age of 2375 ± 75 Ma based on geologic evidence and radiometric data from other units. Thus, the magnetite remanence predates the reset Rb–Sr isochron age of 2040 ± 50 Ma determined for the basalts. Viscous remanence directions confirm the petrologic evidence that the basalts have not been metamorphosed much above lowest greenschist facies. Existing North American Paleoaphebian paleomagnetic data are critically evaluated and a conservative apparent polar wander path drawn. The Thessalon volcanics were extruded at a middle paleolatitude of 35° indicating that the contemporaneous Blind River – Elliot Lake uranium deposits were formed in a warm temperate climate.
Wenkchemna Glacier: ablation complex and rock glacier in the Canadian Rocky Mountains
Authors: Gardner J.
Published: April 2011

The characteristics and behavior of the Wenkchemna Glacier in the Valley of the Ten Peaks of the Canadian Rocky Mountains are described. Early descriptions, old photographs, tree-rings, an annual sequence of photos since 1965, and field observations provide a data base. The Wenkchemna Glacier combines characteristics of ice-cored rock glaciers, ablation complexes, and glaciers, supporting the concept of a transition between these features. It is the product of a unique geomorphic–climatic system where a large mountain wall of northerly exposure produces a glacial micro–climate, a freeze–thaw weathering environment, a high rockfall frequency, and copious avalanche activity that led, in turn, to a thin, active mass of glacier ice that is preserved by a cover of rock debris. The behavior of the Wenkchemna Glacier has lagged behind that of surrounding glaciers by at least 70 years. Stagnation and differential ablation are the primary processes of glacier wastage. The landforms produced by the Wenkchemna Glacier include rock glacier features, such as arcuate ridges of debris, as well as hummocky ablation moraines typical of glacier stagnation.
Paleocene primates from western Canada
Authors: Krause David W.
Published: April 2011

Plesiadapiform primates have been recovered from seven Paleocene sites in western Canada: (1) Roche Percée (Ravenscrag Formation) — Carpodaptes cygneus, Plesiadapis churchilli, Ignacius frugivorus, Micromomys vossae, n. sp.; (2) Police Point (Ravenscrag Formation) — Carpodaptes cf. cygneus, Plesiadapis sp., Ignacius sp.; (3) Calgary site 2E (Porcupine Hills Formation) — Microsyopinae incertae sedis; (4) Cochrane site 11 (Porcupine Hills Formation) — Elphidotarsius russelli, n. sp., Pronothodectes? sp., Paromomys cf. depressidens, Picrodus silberlingi; (5) Erickson's Landing (Paskapoo Formation) — Plesiadapis rex; (6) Canyon Ski Quarry (Paskapoo Formation) — Carpodaptes cygneus; and (7) Swan Hills site 1 (Paskapoo Formation) — Carpodaptes cygneus, Plesiadapis sp.The primate evidence now available from western Canada permits biostratigraphic correlation with Paleocene sites in the western interior of the United States. The Roche Percée, Canyon Ski Quarry, and Swan Hills sites are accorded a late (but not latest) Tiffanian age. Police Point appears to be slightly older and is assigned to the middle Tiffanian, as is Erickson's Landing. A late Torrejonian age is tentatively given Cochrane site 11. The single primate tooth from Calgary site 2E provisionally suggests a Torrejonian age.The evidence from fossil mammals, primarily primates, suggests that the local faunas from sites in the Alberta Foothills (Cochrane and Calgary) are considerably older than those from the Plains (Erickson's Landing and Canyon Ski Quarry). This does not accord with earlier lithostratigraphic studies, which suggest the reverse should be the case.
On shear heating as an explanation for lithosphere–mantle decoupling
Authors: Spanos T. J. T. , Nyland E.
Published: April 2011

Exact solutions can be found for steady fluid flow under constant shear, even if the stress–strain rate relation is nonlinear and shear heating connects the material properties to thermal behaviour. We present such solutions for a Newtonian material in which viscosity decreases exponentially with temperature, and for two empirical equations valid for high temperature creep. The onset of melting limits the range in which these solutions are applicable. If we assume that the region of the low velocity zone for shear waves is close to melting and that drag on this region by plates appears to a first approximation as a constant stress, we can predict surprisingly reasonable values for the plate velocity with respect to the mantle. The low viscosity of the zone becomes a consequence of melt induced by shear heating. Such melt would also explain a low Q and a reduction in shear velocity. A final solution is then given for an inhomogeneous material whose viscosity increases with depth. This can be interpreted as a material whose melting point increases with depth at a faster rate than the temperature of the material.
Fore-reef carbonate mud bioherms and associated reef margin, Upper Devonian, Ancient Wall reef complex, Alberta
Authors: Mountjoy Eric W. , Jull Robert K.
Published: April 2011

The upper Peechee Member of the Ancient Wall reef complex that is well exposed on the southeast margin of Mount Haultain represents the end of the first main depositional cycle of this complex. The uppermost part forms a 15–30 m thick carbonate sequence that extends basinward over deeper water fore-reef detritus and is divisible into three distinct layers: the lower two consist mainly of stromatoropoid and coral bioherms and biostromes and associated calcarenites and calcilutites; the uppermost consists of five small micrite and wackestone bioherms 7.5–22 m long and 4–6 m high; three of these grew around and on top of a 30 m wide stromatoporoid–coral biostrome. Frame-building organisms include laminar and hemispherical colonies of Phillip-sastrea, renalcid algae (often associated with small fenestral cavities), encrusting calcareous algae (Sphaerocodium), and laminar stromatoporoids. Renalcid encrustations of micrites and wackestones on the vertical sides and undersides of bioherms indicate that early submarine cementation was also significant in forming these rigid structures. The bioherms formed during deepening water conditions with agitation and bioerosion too gentle to apron them with detritus but sufficient to fragment and disorient fragile skeletal elements. The sharp contacts and the lack of interfingering with basin strata indicate that the bioherms were drowned before burial by basin calcareous shales.
The seismotectonics of southern Saskatchewan
Authors: Horner R. B. , Hasegawa H. S.
Published: April 2011

Nine earthquakes are known or thought to have occurred in southern Saskatchewan to the present time. This small number of known events is due in part to the fact that earthquakes less than about magnitude 4 could not be instrumentally located in the region before the mid-1960's. The largest earthquake on May 15, 1909, magnitude mb[Formula: see text], was widely felt over central Canada and the north-central United States and could have been located in southern Saskatchewan, northeastern Montana, or northwestern North Dakota. Four recent minor earthquakes, one near Bengough in 1972, two near Radville, and one at Esterhazy in 1976, were all strongly felt over small areas.There is a general spatial correlation between the observed seismicity and the more structurally disturbed areas of the Precambrian basement and overlying sedimentary sequence in the Williston Basin region. In south-central Saskatchewan, four of the instrumentally located earthquakes show a spatial correlation with a large multi-state salt-solution structure marked by a major anomaly in electrical conductivity and a steep Bouguer gravity gradient. The abundant evidence for zones of basement weakness and their control on structures in the Phanerozoic sequence suggests that reactivation of these zones in response to the contemporary stress field may also be responsible for the seismicity.Support is given for the vertical strike-slip mechanism proposed for the 1972 Bengough earthquake. Other mechanisms considered possible for generating earthquakes in Saskatchewan are related to cavity formation in the Prairie Evaporite by either natural or industrial processes, specifically tensional faulting in the cap rock due to overburden pressure. Cavity collapse is not thought to be a likely mechanism for generating detectable seismic waves. Although there is a spatial correlation between some of the observed seismicity and areas of subsurface fluid injection, the absence of any direct in situ stress measurements, of knowledge of the cohesive strength of the rock in areas of fluid injection, and of accurate focal depths precludes any direct correlation.
Paleosalinity and dolomitization of a Lower Paleozoic carbonate sequence, Somerset and Prince of Wales Islands, Arctic Canada
Authors: Veizer Ján , Lemieux Jean , Jones Brian , Gibling Martin R. , Savelle Jim
Published: April 2011

Trace element study of Lower Paleozoic carbonate formations on Somerset and Prince of Wales Islands (Arctic Canada) suggests the following interpretation: (1) Na contents of the formations studied reflect the paleosalinities of their depositional and (or) early diagenetic environments; (2) K is not suitable as a paleosalinity indicator; (3) the post-Allen Bay limestones studied were probably originally (bio)chemical aragonitic muds associated with environments having hypersaline tendencies; (4) Sr distribution of penecontemporaneous – early diagenetic dolostones (Cape Storm, Somerset Island, Peel Sound Formations) suggests that they are replacements of aragonitic muds, frequently in hypersaline settings; (5) the late diagenetic dolostones (Lang River and Allen Bay Formations) are probably hyposaline replacements of CaCO3 precursors deficient in high-Sr aragonite; aragonite may have undergone diagenetic transformation into calcite prior to dolomitization.
Megalineament in southeastern Alaska marks southwest edge of Coast Range batholithic complex
Authors: Brew David A. , Ford Arthur B.
Published: April 2011

The Coast Range megalineament is a prominent, nearly continuous topographic and structural feature that extends southeastward about 550 km (330 mi) from its junction with the Chatham Strait – Lynn Canal fault at Point Sherman to Tongass Passage near the mouth of Pearse Canal where it leaves southeastern Alaska. It probably extends still further southeastward into British Columbia along Work Channel and Chatham Sound – Grenville Channel.The megalineament is a zone a few hundred metres to 10 km (6 mi) wide in which closely spaced joints, foliation, compositional layering, and small faults define the megalineament trend. The zone usually coincides with topographic depressions apparently caused by selective fluvial and glacial erosion of the less resistant rocks of the zone.Studies in the Juneau, Endicott Arm, and Behm Canal areas indicate that the megalineament (1) is locally the site of lateral and (or) vertical separations of no greater than several kilometres; (2) does not mark a major structural or metamorphic discontinuity in the near-surface rocks; (3) may be located near a pre-metamorphic and pre-intrusive discontinuity; (4) is consistently associated with and parallel to steep gradients in both the gravity and aeromagnetic fields; and (5) probably is the surface expression of the western contact, at depth, of the intrusive rocks and gneisses of the Coast Range batholithic complex with the schists to the southwest.
The oxygen isotope composition of the surface crystalline rocks of the Canadian Shield
Authors: Shieh Yuch-Ning , Schwarcz Henry P.
Published: April 2011

The average 18O/16O ratios of the major rock types of the surface crystalline rocks in different parts of the Canadian Precambrian Shield have been determined, using 47 composite samples prepared from 2221 individual rock specimens. The sampling areas include Baffin Island, northern and southwestern Quebec, Battle Harbour – Cartwright, northern District of Keewatin, Fort Enterprise, Snowbird Lake, Kasmere Lake, and Saskatchewan, covering approximately 1 400 000 km2. The granitic rocks from the Superior, Slave, and Churchill Provinces vary only slightly from region to region (δ18O = 6.9–8.4‰) and are significantly lower in 18O than similar rock types from the younger Grenville Province (δ = 9.2–10.0‰). The sedimentary and metasedimentary rocks have δ18O = 9.0–11.7‰ and hence are considerably lower than their Phanerozoic equivalents, possibly reflecting the presence of a high percentage of little-altered igneous rock detritus in the original sediments. The basic rocks in most regions fall within a δ18O range of 6.8–7.6‰, except in northern and southwestern Quebec where the δ-values are abnormally high (8.5–8.9‰). The overall average 18O/16O ratio of the surface crystalline rocks of the Canadian Shield is estimated to be 8.0‰, which represents an enrichment with respect to probable mantle derived starting materials by about 2‰.
Transformation of aragonite to calcite in a marine gasteropod
Authors: Wardlaw Norman , Oldershaw Alan , Stout Mavis
Published: April 2011

A detailed examination of the aragonite to calcite transformation in samples of Strombus gigas from the Pleistocene of British Honduras demonstrates that the process is essentially isochemical with respect to strontium distribution. The contact between original skeletal aragonite and the replacement low magnesian calcite is not represented by visible pore space or by a chalky zone as reported from material described by other authors. A transformation process involving solution films of less than 100 Å (10 nm) and a closed chemical system is considered to be the most reasonable explanation based on the available data.
The effect of Pleistocene climatic variations on the geothermal regime in Ontario: a reassessment
Authors: Allis R. G.
Published: April 2011

A revised glaciation chronology for Ontario that spans the last half million years is derived by combining recent results from oxygen isotope analyses in deep sea cores with evidence from studies of the Pleistocene geology of the province. The chronology suggests that the perturbation to the geothermal gradient may be up to 50% larger than previously thought in central parts of Ontario.
A thermoluminescence dating study of some Quaternary calcite: potential and problems
Authors: Wintle A. G.
Published: April 2011

The basic thermoluminescence (TL) characteristics relevant to dating Quaternary calcite are reviewed and modifications of the basic TL age equation due to the effect of uranium series disequilibrium are discussed. The equivalent doses were measured for six samples whose ages had been previously determined by uranium series dating and for which doses could be calculated: random discrepancies up to ± 200% were found. Tentative explanations for these discrepancies are put forward, the most probable being sample inhomogeneity.
Thermal conductivity measurements on saturated rocks at permafrost temperatures
Authors: King M. S.
Published: April 2011

A simple divided-bar apparatus for studying the thermal conductivity of rocks and soils at permafrost temperatures is described. The apparatus is intended also for use with permafrost specimens tested in their natural frozen state. It has been designed for low heat fluxes and consequent small temperature drops across the test specimen, while retaining a high precision of measurement.Different thicknesses of two water-saturated sandstones and a limestone have been tested as a function of changes in temperature, frozen and unfrozen. Significant corrections for the contact resistance between the specimen and divided bar were determined. The influence of the magnitude of temperature gradient across the specimen was not found to be important for the low gradients employed in these experiments.The measured thermal conductivities show a slight decrease in value with temperature increasing to 0 °C. In the neighbourhood of 0 °C, a sharp reduction in thermal conductivity was observed as the ice–water phase change occurred. It is clear that the magnitude of the thermal conductivity of the rocks depends on their mineral content; quartz, with its high thermal conductivity, plays the predominant role where it is present.
Concave-bank benches on the Squamish River, British Columbia, Canada
Authors: Hickin Edward J.
Published: April 2011

The form, sediments, and possible origin of two concave-bank benches on the Squamish River, British Columbia, are briefly described. They contain the only fine-grained within-channel deposits in this gravel-bed stream and are generally similar to features on the Barwon River in Australia.One concave-bank bench on the Squamish River is a mature feature and the other is currently being formed. Evidence from the latter example indicates that the features, like those on the Barwon River, are deposited in the separation zones developed at the concave bank of very sharp bends. Sediments appear to be supplied from suspensions in dissipating vortices advected into the separation zone. Two processes of vortex advection are briefly discussed.
Relation of magnetic properties of the rocks of the Ukrainian Shield to their composition and metamorphism
Authors: Krutikhovskaya Z. A. , Silina I. M. , Bondareva N. M. , Podolyanko S. M.
Published: April 2011

A magnetization map has been compiled for the Ukrainian Shield. The magnetization contours generally resemble those for the anomalous magnetic field, and this is explained by the coincidence of the directions of the induced and remanent magnetizations for most of the shield rocks.The magnetization map makes it possible to establish a correlation between the magnetization distribution in the shield rocks and the history of evolution and peculiarities of the structural blocks of the shield.The sum magnetizations of the large blocks range from 100 to 550 × 10−3 A m−1. A high magnetization (800–3000 × 10−3 A m−1) is characteristic of the regions composed of the products of metamorphism and granitization of the oldest Early Archean magmatic formations. In these areas regional magnetic anomalies are revealed.In order to study the physical properties and mineral composition of rocks within the areas of two regional anomalies, correlation of magnetization with original composition and degree of metamorphism and granitization has been investigated.The data obtained make it possible to predict the magnetization of the lower crust and to use the magnetic field data in constructing a complex geophysical model for the earth's crust.
The paleomagnetic record of the late Quaternary sediments of Thunder Bay
Authors: Mothersill John S.
Published: April 2011

Graphs can be constructed to show the change in magnetic declination and inclination with time by compiling the values of the natural remanent magnetic directions determined from oriented samples taken along the length of cores of the late-glacial and postglacial lacustrine sequence of Thunder Bay. The change in the magnetic declination and inclination values reflects secular variations of the earth's geomagnetic field. The pattern of oscillatory swings of the paleo-declination and paleo-inclination graphs should provide a useful method of time-parallel correlation from core to core. The utilization of the paleo-declination graph supplemented by the paleo-inclination graph does appear to provide a valid method of time-parallel correlation not only across Thunder Bay but possibly for the Great Lakes area.
The nature of the Late Paleozoic glaciation in Gondwana as determined from an analysis of garnets and other heavy minerals
Authors: Gravenor C. P.
Published: April 2011

Heavy mineral suites from Late Paleozoic sediments from South Africa, Australia, and Antarctica are dominated by garnet. The enrichment of garnet is attributed to the loss of unstable minerals such as pyroxenes and amphiboles by mechanical abrasion in beach and fluvial environments during periods of deglaciation.An analysis of chattermark trails found on the surface of the garnets shows that the percentage of chattermarked garnets is roughly twice that from samples of Pleistocene glacial sediments of North America. As the percentage of garnets with chattermark trails is a function of the distance of glacial transport, it is concluded that the garnets found in the Late Paleozoic glaciogenic sediments have been transported over very long distances, probably as a result of having been recycled many times. As these glacially mature garnets are found in tillite and other glaciogenic deposits which directly overlie bedrock, it is suggested that much of Gondwana was covered for a long period of time by glaciers of continental dimensions and that much of the record of the early part of the Late Paleozoic glaciation is missing due to glacial erosion.
Revision and correlation of late Middle Ordovician stratigraphy northeast of Quebec City
Authors: Belt Edward S. , Riva John , Bussières Louise
Published: April 2011

Autochthonous late Middle Ordovician rock units between Neuville (near Quebec City) and La Malbaie (160 km to the northeast) have been revised lithologically and correlated by means of graptolites. The following rock units have either had a slight modification of their lithologic definition or have been found to extend into a region where they were not previously recognized: Cap-à-l'Aigle Formation, Saint-Irénée Formation, Utica Shale, and Lotbinière Formation. In addition, two new rock units have been named: Beaupré Formation and Moulin River facies (an informal term) of the Trenton Group.The depositional environments of each of the late Middle Ordovician rock units have been briefly identified (although the bulk of evidence is reserved for a later report). Thus, when the various facies are correlated, some important facts emerge about the southern margin of the Laurentian Platform and the rise of the Taconic Orogen to the southeast of Logan's Line. The Deschambault limestone and underlying Cap-à-l'Aigle sandstone were deposited during a marine transgression, after which a structural feature (Montmorency Promontory) developed in the Quebec City to Beaupré area. The promontory was asymmetrical, with a gentle gradient to the southwest, and a steep gradient and a basin to the northeast. Sedimentary thicknesses increased three- to fourfold in the basin northeast of the promontory, and the facies within the basin are markedly different from those over the promontory and southwest. Within the basin there developed deep-water limestone (Moulin River facies), and submarine-fan facies (Saint-Irénée Formation and 'new facies') with interfan microflysch (Lotbinière Formation). Trenton limestone facies on the promontory were deposited in a carbonate bank environment. No Utica Shale is found northeast of the Montmorency Promontory. In contrast, the 'typical' succession of Trenton–Utica–Lotbinière–Lorraine was developed in the region of the promontory and south-west in the St. Lawrence Lowland. An exception is the Beaupré submarine fan that developed over the promontory. All three submarine fans were shed by the rising Taconic Orogen which can be shown by graptolites and the presence of Mg-rich chromite to have been deeply eroded as early as ruedemanni zone time. No Lorraine Group facies are known from the area of our investigation.
Origin of megarhythms in flysch sequences of the Quebec Appalachians
Authors: Lajoie Jean
Published: April 2011

The cyclic and positive sequences observed in the External Domain of the Quebec Appalachians between L'IsIet and Grosses Roches have been interpreted as facies of deep-sea fans that result from progradation. In these conglomerate-bearing sequences, the composition of the detritus changes up-section, which suggests that uplift of the source area played an important role in their vertical evolution. In early and (or) Middle Cambrian time, the source consisted of sedimentary, igneous, and metamorphic terranes. This provenance was rejuvenated in Late Cambrian – Early Ordovician time, and the Lower – Middle Cambrian shelf wa.s uplifted. The stratigraphic evolution of composition observed in these flysch sequences cannot be explained by deep-sea fan progradation.In recent years the general trend in flysch-sequence analysis has been away from tectonic and towards sedimentological interpretations. The stratigraphic evolution of flysch sequences may be due to both tectonic and sedimentary processes. Studies of rock composition, generally neglected by most workers, could be used to make the distinction.
Ochotona and other vertebrates of possible Illinoian age from Kelso Cave, Halton County, Ontario
Authors: Churcher C. S. , Dods R. R.
Published: April 2011

Disarticulated skeletal elements of American? toad (Bufo sp., ?B. americanus), grouse (Canachites canadensis or Bonasa umbellus), varying hare (Lepus americanus), cottontail rabbit (Sylvilagus floridanus), large pika (Ochotona sp.), woodland deer mouse (Peromyscus maniculatus), muskrat (Ondatra zibethicus), little brown bat (Myotis lucifugus), and striped skunk (Mephitis mephitis) have been identified from a travertine cemented dolomite breccia from a demolished cave in the Lockport Formation of the Niagara Escarpment west of Milton, Ontario. Pollen grains recovered from the matrix show that spruce (Picea sp.), pine (Pinus sp.), birch (Betula sp.), oak (Quercus sp.), elm (Ulmus sp.), lime (Tilia sp.), and black walnut (Juglans nigra) coexisted with the fauna. The flora resembles that radiocarbon dated to between 10 500 and 9500 years BC from nearby Crawford Lake. However, the presence of Ochotona sp. suggests a possible Illinoian age for the deposit on the known occurrences of Illinoian Ochotona in Maryland and West Virginia, and the record of Illinoian giant pikas in Alaska and eastern Asia.
Radiocarbon dates from Boone Lake and their relation to the 'Ice-free Corridor' in the Peace River District of Alberta, Canada
Authors: White James M. , Mathewes Rolf W. , Mathews W. H.
Published: April 2011

Four new radiocarbon dates spanning the period of 10 740 + 395 to greater than 30 000 BP from a core taken from the bed of a high-level lake in the Saddle Hills of northwestern Alberta suggest that these hills escaped glacial overriding during late Wisconsinan glaciation.
A model for Archean tectonism. Part I. The thermal conditions
Authors: West G. F. , Mareschal J.-C.
Published: April 2011

The feasibility of a tectonic model that would explain some of the major features of the Archean Superior Province is examined. This model assumes that about 3.5 Ga (1 Ga = 109 years) ago, a thin granitoid crust covered most of the Earth and there was no clear separation into oceans and continents. Basalts would partially melt in the upper mantle and rise to the surface forming thick volcanic plateaus. After cooling, the dense volcanics (2.9 g/cm3) overlying the granitic crust (2.65 g/cm3) would sink if both materials' viscosity were reduced. A succession of cycles of volcanism and vertical tectonism may have lasted until the Kenoran orogeny. One-dimensional thermal modelling shows that under reasonable assumptions, the temperature jump which follows the deposition of a volcanic layer at −3.2 Ga is sufficient to reduce the viscosity by five orders of magnitude. This was no longer the case under post Kenoran conditions when radioactive heat production was lower, and deep erosion had reduced even further the amount of radioactivity in the crust.
Granitoid complexes and the Archean tectonic record in the southern part of northwestern Ontario
Authors: Schwerdtner W. M. , Stone D. , Osadetz K. , Morgan J. , Stott G. M.
Published: April 2011

Two principal, possibly overlapping, periods of tectonic deformation can be distinguished in the Archean of northwestern Ontario, a period of dominantly vertical-motion tectonics and a period of dominantly horizontal-motion tectonics. Gigantic diapirs of foliated to gneissic tonalite–granodiorite developed during the first period and appear to be responsible for the gross structure of, and the major folds within, the metavolcanic–metasedimentary masses ("greenstone belts"). These diapirs are most likely due to mechanical remobilization of early tabular batholiths which originally intruded the oldest supracrustal rocks presently exposed. Later massive to foliated, dioritic to granitic plutons that vary from concordant, crescentic plutons to partly discordant plutons of various shapes and sizes were emplaced into the diapirs.The second period of tectonic deformation is characterized by large-scale dextral shearing and the development of major transcurrent faults under northwesterly regional compression. The strike-slip motions of this period outlasted the late plutonism, and led to the development of mylonitic zones which cut all Archean granitoid plutons.
Surface textures and rounding of quartz sand grains on intertidal sandbars, Bay of Fundy, Nova Scotia
Authors: Middleton Gerard V. , Davis Patricia M.
Published: April 2011

Intertidal sands in the Minas Basin are mineralogically immature, and are generally medium grained and moderately well sorted. Quartz grains show a wide range of roundness: mean roundness is subangular, but rounded to well rounded grains are also present. The sands are derived mainly from coastal erosion of Pleistocene tills and outwash and Triassic sandstones.Scanning electron microscope examination of the surface textures of more than 40 samples of source materials and tidal sands reveals that although many of the textures are relict, tidal sands show high, smoothed surfaces with non-oriented V's, and low areas with 'patchy growths', neither of which are present on source sands. Rounding of grains is undoubtedly taking place in the tidal environments, but much of the roundness is inherited from Triassic source material, and new surface textures are developed most rapidly on grains already partly rounded.Average distances of grain transport in the layer of sand moving on the bar surface is of the order of 1 m per tidal cycle, and allowing for reworking of the entire mass of sand in the bars, this results in a long term transport rate of only about 10 m per year. For the distance of transport, sediment transport by tides is probably more efficient at rounding sand grains than transport by rivers, but less efficient than transport by waves or wind. Geologically long periods of reworking by tides would be necessary to produce texturally supermature sands.
The variation of elastic wave velocities and quality factor Q of a sandstone with moisture content
Authors: Pandit B. I. , King M. S.
Published: April 2011

Elastic wave velocities and the quality factor Q were measured on specimens of Berea Sandstone as their water vapor content was increased by exposure to an environment of increasing relative humidity (RH). At a maximum value of RH (= 0.98), the moisture absorbed was about 0.15% (vs. 9.62% for full saturation) of their dry mass.The bar velocities in the torsional and longitudinal vibrational modes were measured in the frequency range 1–20 kHz, while the pulse first-arrival compressional and shear-wave velocities were obtained at 820 kHz. Over the range of variation in relative humidity from 0.0 (vacuum ~1 Torr) to 0.98 the velocities showed a decrease of 20–30%, the bar velocities undergoing the greater change. Over the same range the Poisson's ratio fell from 0.2 to 0.1.The value of the quality factor Q fell sharply from ~200 to ~50 during the initial increase (about 0.01% by weight) in the moisture content. Further addition of water vapor produced no significant change in Q for either mode. Also, no systematic variation of Q with frequency was observed. However, when the amount of moisture in the specimens increased to about 0.15% by weight, not only did the Q values decrease but also began to show a frequency dependence. This change in the frequency variation of Q suggest that, while the water molecule layers initially absorbed by the specimens form a solid phase, a thickness is reached beyond which they depict bulk water behavior. A rough estimate of this thickness was found to be about 110 Å.On a mesuré la vitesse des ondes élastiques et le facteur de qualité Q sur des spécimens de grès de Berea lorsqu'on augmentait leur teneur en vapeur d'eau par exposition à un milieu d'humidité relative (HR) croissante. Pour la valeur maximale de HR (= 0.98), l'humidité absorbée était d'environ 0.15% (par rapport à 9.62% pour la saturation complète) de la masse à l'état sec.
Englacial temperature and deformation of a rock glacier in the Kluane Range, Yukon Territory, Canada
Authors: Johnson Jr. J. P. , Nickling W. G.
Published: April 2011

Measurements of subsurface movement and temperatures from a 17-m bore hole in R.G, II, a rock glacier overlooking Kluane Lake. Yukon Territory, suggest that it is becoming inactive. Present movement appears to be intermediate between a Newtonian viscous flow and one in which velocity decreases exponentially with depth. An older surface has been identified beneath a lobe indicating that the rock glacier has been subject to periods of different rates of activity. Between 1971 and 1976 the internal summer temperatures of all but 1.5 m of the middle section of the bore hole rose to above freezing, and evidence of new thermokarstic development appeared. Although the terminal area of R.G. II appears to have little ice remaining in it, movement is expected to continue by creep until stability is achieved because of the relatively steep bedrock slope on which the rock glacier is situated.
Preliminary analysis of a gravity profile across the Bonnet Plume Basin, Yukon Territory, Canada: an aid to coal basin evaluation
Authors: Sobczak L. W. , Long D. G. F.
Published: April 2011

Preliminary analysis of gravity anomalies across the Bonnet Plume Basin indicates that the gravity method can be used as a relatively inexpensive method of establishing basin structure and approximating formation thickness in coal basins with little to no subsurface control, providing that density contrast between the coal-bearing strata and underlying rocks is sufficiently high. In the Bonnet Plume Basin gravity measurements recorded along an east–west profile give Bouguer anomalies which vary from −42 to −82 mGal and place constraints on geological models which can be applied to the clastic fill of the Cretaceous–Tertiary basin. Within these constraints the Bonnet Plume Formation can be modelled as an eastward, gently dipping (1–9°) sequence of coal-bearing rocks which attains a maximum thickness of between 760 m and 4.7 km in a region 7 km west of Knorr Fault. The unconformity between the Bonnet Plume Formation and underlying Proterozoic rocks, east of this zone of maximum thickness, dips to the west at between l0and 44°. Accurate estimates of both the thickness and dip of the sequence cannot be made due to inadequate knowledge of the subsurface distribution of the upper (low density) and lower (high density) members of the formation. Application of a two-layer model for the Bonnet Plume Formation would indicate that the upper, lignite-bearing member of the formation may be more restricted than previously suspected and that the greater proportion of the basin to the south of the line of profile is underlain only by the lower member, containing subbituminous coals.
Pedogenesis and tephrochronology of loess derived soils, Hinton, Alberta
Authors: Dumanski J. , Pawluk S. , Vucetich C. G. , Lindsay J. D.
Published: April 2011

The loess derived soils of the Hinton district provide a record of soil formation for the entire postglacial period. Loess originates from the shorelines of Brûlé Lake and from the sandbars and braided channels of the Athabasca River.The geochronology of the loess, as established through the study of paleosols and volcanic ash beds, indicates that loess deposition was continual but irregular. Soil formation occurred contemporaneously with loess deposition, and varying soil morphologies were attributed to differing local rates of loess accumulation. There was no evidence for marked climatic change during the Holocene in the study area, but increased loess supply after 4000 years BP may reflect gradual change.