bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a braided-fluvial facies model for the Devonian Battery Point Sandstone, Québec
Authors: Cant Douglas J. , Walker Roger G.
Published: April 2011

Eight distinct facies have been defined in a 110 m thick section of the Lower Devonian Battery Point Sandstone near Gaspé, Québec. The first is a scoured surface overlain by massive sandstone with mudstone intraclasts. Facies A and B are trough cross-bedded sandstones, with poorly- and well-defined stratification, respectively. Facies C and D consist of large isolated, and smaller multiple, sets of planar cross-stratified sandstones, respectively. Facies E comprises large sandstone-filled scours, facies F comprises ripple cross stratified fine sandstones with interbedded mudstones, and facies G comprises sets of very low angle cross-stratified sandstones.The overall context of the Battery Point Sandstone, the presence of rootlets, and the abundance of trough and planar-tabular cross bedding, all suggest a generally fluvial environment of deposition. Analysis of the facies sequence and interpretation of the primary sedimentary structures suggest that channel development began by scouring, and deposition of an intraclast lag. Above this, the two trough cross bedded facies indicate unidirectional dune migration downchannel (vector mean direction 291°). The large planar tabular sets are associated with the trough cross bedded facies, but always show a large (almost 90°) paleoflow divergence, suggesting lateral movement of in-channel transverse bars. The smaller planar tabular sets occur higher topographically in the fluvial system, and the rippled silts and muds indicate vertical accretion. Because of the very high ratio of in-channel sandy facies to fine-grained vertical accretion facies, and because of the evidence of lateral migration of large in-channel bars, the Battery Point River appears to resemble modern braided systems more than meandering ones.
On the position of the Variscan front in southern New Brunswick and its relation to Precambrian basement
Authors: Rast N. , Currie K. L.
Published: April 2011

The Variscan front is marked by a zone of cataclasis that generally follows an older and larger mylonite zone, but locally cuts across relatively undeformed Precambrian rocks. The older mylonite zone probably developed in Late Precambrian (Avalonian) time. Correlative Precambrian rocks extend across both the Variscan front, and the Bellisle fault to the northwest.
A conceptual model of watershed response to rainfall, developed through the use of oxygen-18 as a natural tracer
Authors: Sklash M. G. , Farvolden R. N. , Fritz P.
Published: April 2011

Oxygen-18 is a stable, naturally occurring isotope of oxygen, whose concentration in a particular rainfall event may be quite different from its concentration in groundwater. It is on the basis of this difference that storm hydrographs recorded at seven stream gauges in the Big Creek and Big Otter Creek basins of Southern Ontario were separated into their components as to source. The storm hydrographs considered in this study were the result of a severe spring storm that triggered devastating floods in the adjacent, heavily populated, Grand River drainage area.Using the oxygen-18 technique, it was found that groundwater was the major component of storm runoff, providing more than 50% of the peak discharge. These results are consistent with natural tracer studies on basins one to two orders of magnitude smaller and in different hydrogeologic environments.By comparing oxygen-18 and specific conductivity data, storm runoff was divided into groundwater, direct rainfall, and direct runoff components.On the basis of the oxygen-18 and specific conductivity data, it was concluded that storm runoff in the study area was generated primarily through increased groundwater discharge. It is believed that increased hydraulic gradients, near or at the stream channel, which develop quickly after a rainfall, are responsible for the increase in groundwater discharge.
The description and phenetic relationships of a new Ichthyosaur genus from the Upper Jurassic of England
Authors: McGowan C.
Published: April 2011

A large and previously unknown ichthyosaur is reported from the Kimmeridge Clay (Upper Jurassic) of Stowbridge, Norfolk, England. The only valid genera described from the Upper and Middle Jurassic are considered to be Ophthalmosaurus Seeley and Nannopterygius von Huene, and since the Stowbridge specimen is distinct from these, a new genus and species, Grendelius mordax gen. et sp. nov., are erected. Using cluster and principal coordinates analyses, G. mordax was found to have closest phenetic affinities with Platypterygius americanus (Nace) of the North American Cretaceous, and with an undescribed ichthyosaur from the Middle Triassic of Switzerland, and least phenetic affinity with Ophthalmosaurus discus (Marsh).The phenetic analysis also revealed that the division of the Ichthyosauria into latipinnates and longipinnates is questionable. Stenopterygius quadriscissus (Quenstedt), long considered a longipinnate, is herein shown to have closer phenetic affinity with latipinnate ichthyosaurs. The close phenetic affinity between the skulls of P. americanus and the undescribed Swiss ichthyosaur is inconsistent with currently held views of cranial evolution in ichthyosaurs, and points to the shortcomings of tracing evolutionary trends in temporal sequences of fossils.
Distribution of surficial sediments of the central and southern Strait of Georgia, British Columbia
Authors: Pharo C. H. , Barnes William C.
Published: April 2011

The Strait of Georgia is a long, narrow, semi-enclosed basin with a restricted circulation and a single sediment source, the Fraser River, providing practically all the sediment now being deposited in the Strait. This river is building a delta into the Strait from the east side near the south end. Ridges of Pleistocene deposits within the Strait and Pleistocene material around the margins, like bedrock exposures, provide local sources of sediment of only minor importance.Sandy sediments are concentrated in the vicinity of the delta, and in the southern and southeastern parts of the Strait. Mean grain size decreases from the delta toward the northwest along the axis of the Strait, and basinwards from the margins. Silts and clays are deposited in deep water west and north of the delta front. Bedrock or poorly sorted sediments containing gravel occur near tidal passes, on the Vancouver Island shelf area, on ridge tops within the Strait, and with sandy sediments at the southeastern end of the study area. The Pleistocene ridges are areas of nondeposition, having at most a thin veneer of modern mud on their crests and upper flanks.
Pingo investigations, north-central Banks Island, Canadian Arctic
Authors: Pissart A. , French H. M.
Published: April 2011

A number of pingo-like mounds, located in the north-central part of Banks Island, are described. The features are situated on low terraces within the valleys of the Thomsen River and its small tributary, Able Creek. Many are elongate in plan and partially collapsed in form. Sections excavated across four of the mounds reveal cores of massive ice. It is hypothesized that these ice bodies are the result of both segregation and injection processes, induced by the freezing of localized sub-channel taliks.
New cheirurinid trilobites from the lower Whittaker Formation (Ordovician), southern Mackenzie Mountains
Authors: Ludvigsen Rolf
Published: April 2011

Two new genera of cheirurinid trilobites are described from the lower Whittaker Formation (?Rocklandian to Edenian; late Middle and early Late Ordovician) of the southern Mackenzie Mountains. The monotypic genus, Whittakerites n. gen., is a probable descendant of Ceraurus and is presently known only from northern Canada. Borealaspis n. gen. is established for two species from northern Canada, one of which possibly occurs in northern Greenland, and includes B. numitor (Billings) from Anticosti Island. New species described are Whittakerites planatus, Borealaspis whittakerensis, and B. biformis.
The geochemistry of the Archean Bourlamaque batholith, Abitibi, Quebec
Authors: Campiglio C. , Darling R.
Published: April 2011

The Bourlamaque batholith, of Archean age, outcrops in the Val d'Or mining camp of northwest Quebec. In order to describe its geochemistry and interpret its origin, 82 samples of the main igneous body, of synplutonic dykes, and of related later dykes were studied petrographically and analysed for 21 elements. Geochemical interpretation was based mainly on petrochemical variation (Larsen) diagrams and on abundance ratios calculated for several element pairs. The batholith is composed of at least two consanguineous and differentiated dioritic intrusions, probably introduced as sills into surrounding flat-lying volcanic rocks, and now metamorphosed to the greenschist facies. Local metamorphism appears to have been essentially isochemical except for CO2 and Cu. The redistribution of copper during metamorphism seems potentially important for mineral exploration. The Bourlamaque batholith, poor in K, Rb, Sr, Mg, Cr, and Ni, seems chemically very like the enclosing Archean volcanic rocks and similar but not identical to Phanerozoic calc-alkaline suites.
Petrology and emplacement of the Los Pinos pluton, southern California
Authors: Walawender M. J.
Published: April 2011

The Los Pinos gabbro is located on the eastern margin of the gabbro sub-belt of the Peninsular Ranges batholilh. Two lithologic sequences are recognized in this pluton. The outer group consists of bimodal assemblages of hornblende and plagioclase in several textural varieties, whereas the inner group contains a variety of olivine–plagioclase rocks. Symplectitic intergrowths of spinel, amphibole, and orthopyroxene have developed wherever the olivine and plagioclase were in contact. The outer group is generally the older of the two, although there is evidence suggesting that their emplacement overlapped in time. The contact between the two groups is characterized locally by sequences of comb layers up to 65 m thick. Major-element chemical analyses emphasize the differences between the two groups. The outer group is generally richer in total alkalis, titanium, and silica. Variation diagrams suggest that different differentiation mechanisms operated within each group.Textural and published experimental data suggest that the two groups are derived from a parent magma by clinopyroxene fractionation at PT > 5 kbar. The more silicic differentiates were emplaced at shallower levels into a series of regionally metamorphosed pelitic rocks. Volatile streaming in restricted channels along a conduit zone and periodic degassing of the melt, possibly through volcanic eruption, produced the comb layering in the summit region. The remaining fraction intruded along the old conduit zone. Differentiation at these shallower levels (PT < 5 kbar) produced the olivine–plagioclase cumulates. The symplectic intergrowths in these units formed at this shallower level prior to the solidification of the melt.
Stratigraphic relationships of the Malbaie Formation (Devonian), Gaspé, Quebec
Authors: Rust Brian R.
Published: April 2011

The upper boundary of the Middle Devonian Malbaie Formation is an angular unconformity below the Carboniferous Cannes de Roche Formation; although previously unrecognised, it is well exposed along the coast west of Pte-St-Pierre, Quebec. The lower boundary defined in 1935 on the shore northwest of Pte-St-Pierre is thought to be incorrect, representing stata about 500 m above the base of the formation. Logan's proposal that the boundary at this location is a fault contact with the Lower Devonian Battery Point Formation is accepted as a better interpretation.
Ultrasonic wave measurements on frozen soils at permafrost temperatures
Authors: Kurfurst P. J.
Published: April 2011

An ultrasonic pulse technique was used in the laboratory to measure compressional and shear wave velocities on frozen soil samples with various ice contents. Measurements were made on a variety of samples, which differed in type of material, geographical location, and ice content, at temperatures ranging from −7 to +1 °C. Three series of tests were run on specimens from the Norman Wells, Fort Good Hope, and Eureka areas, Northwest Territories. The first series of specimens was tested under uniaxial stress conditions, whereas the measurements for the second and third series were done under triaxial stress conditions. The results measured on samples from the Norman Wells and Eureka areas were compared with the results obtained from shallow seismic profiles shot in the field at the sampled drill sites at the time of drilling. The values of field velocities lie within the range of laboratory measurements, and therefore prove that the laboratory tests provide a measure of control in the interpretation of seismic records.
Lower Palaeozoic trace fossils from eastern Newfoundland
Authors: Bergström Jan
Published: April 2011

Arthropod trace fossils are described from the Cambro-Ordovician sequence of Conception Bay. The sedimentological and ichnofaunal aspect is typical of an Acado-Mediterranean Province, but a few unique forms occur, including Rusophycus leifeirikssoni n. ichnosp. and R. cf. R. jenningsi. An effort is made to separate telopodite and exite scratches and to understand what kinds of trilobites were involved. Together with the description of the arthropod trace fossils, a list of the other trace fossils and short review of the local geology is given.
Heat generation in the Coast Range Complex and other areas of British Columbia
Authors: Lewis T. J.
Published: April 2011

A γ-ray spectrometer has been used to measure the concentrations of uranium, thorium, and potassium in plutonic rocks from three areas of the Cordillera in British Columbia. Samples of crystalline rock from southeastern British Columbia, including the Nelson batholith, and samples from the Jennings River area of northern British Columbia, including the Cassiar batholith, have similar heat productions, the average being 2.5 μWm−3 (6.1 hgu). Samples of the less potassic southern Coast Range Crystalline Complex between 50° and 51 °N have a significantly lower heat production: the average value for quartz diorites is 0.50 μWm−3 (1.2 hgu), for granodiorites, 1.0 μWm−3 (2.4 hgu), and for quartz monzonites, 1.3 μWm−3 (3.1 hgu). For this part of the Coast Range the average heat generation, 0.79 μWm−3, and the average ratio of thorium to uranium content, 2.1, are low for crystalline rocks.These results for the Coast Range support the hypothesis that this material is primitive, and was originally part of the oceanic crust, or a mixture of oceanic and continental crust. These heat production values are needed along with surface heat flux to construct thermal models of the crust and upper mantle.
Electrical properties of natural clay permafrost
Authors: Olhoeft Gary R.
Published: April 2011

The resistivity, dielectric constant, and loss tangent of natural clay permafrost samples that have never been thawed have been measured as functions of temperature, applied uniaxial confining load, and applied electric field strength. DC resistivities are on the order of 105 ohm-m at −10 °C, with the complex resistivity becoming strongly frequency dependent within and above the range of 10 to 103 Hz (resistivity decreasing with increasing frequency). Below 103 Hz, the electrical properties are slightly dependent upon applied electric held, and below 105 Hz, the electrical properties are very strongly dependent upon applied uniaxial confining load. Several different mechanisms are responsible for the observed properties, including ionic conduction, a colloidal response that is similar to a Maxwell-Wagner type of effect, the relaxation of Bjerrum defects in ice, the relaxation of the unfrozen water molecules, and a possible relaxation of organic molecules in the unfrozen water sheath surrounding clay particles.
Shape, size, and orientation of muscovite crystals in a schist of variable metamorphic grade
Authors: Rivers T. , Fyson W. K.
Published: April 2011

Measurements of muscovite crystals from a pelitic schist unit show that with an increase in metamorphic grade from the lower to the upper amphibolite facies the crystals on average become larger, more equidimensional in shape (the ratio of length to thickness decreases) and the number per unit volume of rock decreases. In the high grade rocks all sizes of crystals, including small inclusions of muscovite within porphyroblasts of plagioclase feldspar, tend to be relatively equidimensional. The change in shape is thus not simply related to the increase in average size, and the two variables must be considered as independent. Both variables reduce the surface area of the crystals relative to the volume as the metamorphic grade increases.Contrary to previous estimates of the preferred orientations of micas, small muscovite crystals from lower grade zones are more scattered in orientation than larger crystals from higher grade zones. The scatter is mainly due to the presence in the low grade rocks of short, relatively equidimensional crystals lying at high angles to the foliation.It is suggested that the textural changes reflect processes of continuous recrystallization and growth during prograde metamorphism and the development of the schistosity. Crystals may have reached an equilibrium shape, which is temperature dependent. These changes may be driven by surface energy forces, so that the total interfacial free energy of the rock tends to be minimized for any metamorphic grade.
Trace fossils from the Silurian Chaleurs Group of southeastern Gaspé Peninsula, Québec
Authors: Pickerill R. K. , Roulston B. V. , Noble J. P. A.
Published: April 2011

A suite of previously undescribed trace fossils from the three main sections of the Silurian (Chaleurs Group) of the southeastern Gaspé Peninsula are examined in detail. The ichnofauna includes a diverse assemblage of forms produced essentially by vermiform and other problematica (Chondrites,Cosmorhaphe; Diplocraterion parallelum Torell, Gyrophyllites, Monocraterion, Planolites annularius Walcott, Planolites cf. beverleyensis (Billings), Rhizocorallium cf. irregulare (Mayer), Scalarituba missouriensis Weller, Skolithos, Zoophycos, pholadid-like bur-rows and grazing trails). The trace fossils occur in four distinctive and recurring associations. Three of these associations, the Scalarituba – Cosmorhaphe, Chondrites, and Diplocraterion associations are useful paleobathymetric and paleoenvironmental indicators, as they all occur in lagoonal, intertidal, or shallow subtidal regimes. The Scalarituba – Cosmorhaphe and Chondrites associations are characterized by shallow burrows and developed in moderately low energy conditions. The monospecific Diplocraterion association developed on an unstable substrate subject to higher rates of sedimentation. The fourth, Zoophycos association, is found in rocks deposited in variable water depths and is a much less useful paleobathymetric and paleoen-vironmental indicator so that conclusions regarding its distribution must be made with extreme caution.
New Hebrides trench: subduction rate from associated lithospheric bulge
Authors: Dubois J. , Launay J. , Recy J. , Marshall J.
Published: April 2011

We present new data on the lithospheric bulge in the vicinity of the Loyalty and New Hebrides Islands, and attempt to interpret the difference of the topographic profile of the outer wall of the New Hebrides trench from a theoretical profile. The free edge of the lithospheric plate appears to correspond to a line of maximum seismic strain release. The uplift rate and consequently the subduction rate have been calculated from studies of the dynamic aspect of the bulge and from 230Th/234U ages of raised coral terraces.
Late Pleistocene Muskox (Ovibos) from the Early Wisconsin at Scarborough Bluffs, Ontario, Canada
Authors: Churcher Charles S. , Karrow Paul F.
Published: April 2011

An isolated right manual cannon-bone (fused metacarpals III + IV) of Ovibos moschatus has been identified from sediments at Scarborough Bluffs, Ontario, probably from stream deposits of the Pottery Road Formation that overlie the Scarborough Formation clays. This is the first record of muskox from an Early Wisconsin horizon at Scarborough.
Reworked Middle Wisconsinan (?) plant fossils from the Brampton Esker, southern Ontario
Authors: Karrow P. F. , Harrison W. , Saunderson H. C.
Published: April 2011

Plant fossils, consisting of abraded pieces of wood, seeds, and pollen, occur near the bottom of the Armbro gravel pit in a till-capped esker near Brampton, Ontario. A radiocarbon date suggests a Mid-Wisconsinan age for the wood, whereas stratigraphic evidence suggests a Port Huron age for the enclosing sediments. The plant fossils indicate conditions similar to those now found in the southern boreal forest. Derivation of the plants from buried Middle Wisconsinan interstadial sediments to the southeast is suggested.Plant remains in glacial deposits should normally be assumed to be reworked; radiocarbon dates on such fossils do not date the enclosing sediment.
Dentaries of small theropods from the Judith River Formation (Campanian) of Alberta, Canada
Authors: Sues Hans-Dieter
Published: April 2011

Three dentaries of small theropod dinosaurs from the Judith River Formation of Alberta are described and their taxonomy is discussed. Two are referable to the Dromaeosauridae (Dromaeosaurus sp.) and the other to the Saurornithoididae. The structural differences seem to support recognition of two distinct families, Dromaeosauridae and Saurornithoididae, as proposed by some authors on the basis of other structural differences.
Fractionation trends in the Bay of Islands ophiolite of Newfoundland: polycyclic cumulate sequences in ophiolites and their classification
Authors: Church W. R. , Riccio L.
Published: April 2011

The fractionation range of the cumulate sequence of the allochthonous Bay of Islands ophiolite of the Western Platform of Newfoundland, measured in terms of the FeO(tolal)/MgO ratios of the liquids from which they were derived, encompasses entirely the range of known values exhibited by the overlying dikes and pillow lavas. Cryptic variations within the cumulate sequences are irregular, often inverse, and the crystallization sequences found in the cumulates suggest that they were formed from at least three different basaltic magma types, one of which is unusual in having given rise to co-existing highly aluminous clinopyroxenes and spinels. These features suggest that crystallization of the Bay of Islands plutonic rocks took place in an 'open system' magma chamber that was tapped repeatedly during fractionation to form dike rocks and lavas. Most of the cumulate rocks of the Bay of Islands ophiolite formed according to the crystallization sequence ol–cpx–(opx) or the sequence ol–plag–cpx–(opx). In contrast, the cumulate rocks of the Betts Cove ophiolite, located within the Fleur de Lys orthotectonic zone of the Newfoundland Appalachians, crystallized according to the sequences ol–opx–cpx and ol–cpx–plag. This difference in the nature of the cumulate sequences within the Bay of Islands and Betts Cove ophiolites is also reflected in the Ti characteristics of the basaltic rocks of the ophiolites, and in the morphology of the gabbroic units. Comparison with Mesozoic ophiolites suggests, as a general rule, that within ophiolite cumulate successions there is a tendency for ol–opx sequences to be followed by ol–cpx sequences, and for ol–cpx sequences to be followed by ol–plag sequences. Such a relationship may be related to processes involving remelting of lower-temperature crystallization products in a system open to either continuous or periodic additions of high temperature basaltic liquid. In terms of oceanic structures the Bay of Islands ophiolite corresponds to sonobouy model 2 of Christensen and Salisbury: the basal high velocity layer corresponding to the olivine-gabbro cumulate rocks, and the lower velocity 'gabbroic' layer to the upper part of the olivine-free cumulate sequence and overlying massive uralitized roof gabbro and dike rocks.
A method of distinguishing regional directions of jointing and of identifying joint sets associated with individual geologic structures
Authors: Currie J. B. , Reik G. A.
Published: April 2011

Geologic literature on jointing contains little reference to the problem of separating regional joint-set directions from those of joint sets related to individual structures. From study of joints in Cardium strata near South Ram River in the Foothills of central Alberta, a method is proposed by which to make this separation. The method is suggested as a means of distinguishing those widely distributed directions of jointing that may owe their origin to regional uplift and erosional unloading, from those joint sets that are directly related to development of a single structure, such as a fold. Because of the close connection between jointing and development of fracture porosity and permeability in the subsurface, there is need to predict both those joint-set orientations which will probably occur on a regional scale and those sets which are more likely to be localized in their incidence.
Llandoverian and Wenlockian brachiopods from the Canadian Cordillera
Authors: Lenz Alfred C.
Published: April 2011

Llandoverian and Wenlockian age brachiopods are described from five localities in the southern and northern Canadian Cordillera. The majority of brachiopods were collected at, or close to, the shallow water platform carbonate – deep water graptolitic shale and limestone facies transition. Most brachiopods are members of moderate to deep water brachiopod communities referred to the Dicaelosia–Skenidioides Community. Genera which are common in the fauna include Skenidioides, Dicaelosia, the smooth atrypid Cryptatrypa, and rhynchonellids Ferganella and Rhynchotreta, and at one locality only, pentamerids.Newly described species consist of Ancillotoechia pentaforma, Cryptatrypa glaberconcha, C. rotunda, Epitomyonia sekwiensis, E. tripseptata, and Ferganella chattertoni.
A late Wisconsinan Coleopterous assemblage from southern Ontario and its environmental significance
Authors: Ashworth Allan C.
Published: April 2011

A flood debris assemblage of fossil Coleoptera is described from a 10 600 year old terrace deposit in southern Ontario. It is a small sample of the fauna that had colonized the region after deglaciation and although the species are extant, the assemblage is a surprising mixture of faunistic elements for which there is no known modern analog. Species with wide-spread boreal, arctic-alpine, northwestern boreal, southern boreal, and eastern distributions are recorded. The present ecologic and geographic distributions of the species indicate a valley environment with similar habitat diversity and climate to those which characterize the tundra–forest transition zone of northern Canada. This interpretation is supported by macroscopic plant evidence but conflicts with pollen evidence which implies a climate with warmer summers. To resolve the problem it is proposed that the valley fauna and flora survived in an isolated cold microenvironment surrounded by regionally warmer conditions and for which analogies presently exist on the north and east shores of Lake Superior.
Geophysical studies on the eastern continental margin of Baffin Bay and in Lancaster Sound
Authors: Jackson H. R. , Keen C. E. , Barrett D. L.
Published: April 2011

The results of three crustal refraction lines on the western margin of Baffin Bay and one in Lancaster Sound are described. The refraction measurements in Baffin Bay along with earlier refraction, gravity, magnetic, and seismic reflection data are used to define the boundary between continental and oceanic crust. The results suggest that the transition from continental to oceanic material takes place in about 30 km. The seismic refraction data also suggest a sedimentary basin on the continental shelf with at least 6 km thickness of sediment which, however, thins rapidly near Baffin Island. This basin is truncated under the slope by either a basement high or carbonate rocks. Lancaster Sound is filled by about 10 km of sediments that could be either of Mesozoic or Paleozoic age based on comparisons with velocities in nearby wells. The sedimentary and structural characteristics of Lancaster Sound are discussed and related to the concepts of sea-floor spreading and continental drift.
Freshwater shelled invertebrate indicators of paleoclimate in northwestern Canada during late glacial times
Authors: Delorme L. D. , Zoltai S. C. , Kalas L. L.
Published: April 2011

Paleoclimatic interpretations based on shelled invertebrates from four sites in the northwest corner of the Northwest Territories, Canada, during the time interval 14 410–6820 years BP, indicate that the mean annual temperature was about 8.2–11.6 °C higher than at present, and that the annual precipitation was about 55–234 mm greater than at the present time. Based on potential evapotranspiration, it can be computed that the length of the growing season was about 156 days long as compared to between 90 and 135 growing days at the present time for the same area.
Carbon 14 and tritium measurements of groundwaters in the Eaton River Basin and in the Mirabel area, Quebec
Authors: Simard Georges
Published: April 2011

Twenty-nine carbon 14 measurements and 39 tritium determinations were performed on groundwater samples collected from various hydrostratigraphic units of the Eaton River Basin in the Quebec Appalachians and of the Mirabel area in the St. Lawrence Lowlands. The age of water contained in the Quaternary sand and gravel aquifers laid down in preglacial valleys of the Eaton River Basin as well as, that contained in the Cambro-Ordovician carbonate rocks underlying the Mirabel area is shown to be controlled by the permeability of the medium through which recharge occurs. Ages vary from recently infiltrated water to groundwater nearly 10 000 radiocarbon years old. The dates have been adjusted for the limestone dilution effect using an initial carbon 14 of 60% modern far carbonate rocks and 85% modern for detrital rocks.
Tourmaline concentrations in Proterozoic sediments of the southern Cordillera of Canada and their economic significance
Authors: Ethier V. G. , Campbell F. A.
Published: April 2011

Local concentrations of tourmaline occur in the lower Proterozoic (Helikian) Aldridge Formation of southeastern British Columbia, in some places in association with stratiform lead–zinc mineralization as at the Sullivan, Stemwinder, and North Star orebodies. The amount of boron in the rock is as much as two orders of magnitude above average levels reported for the Aldridge Formation or other similar types of sedimentary rocks. The concentrations are not detrital, but are caused by an anomalously high boron level, in a local area, at the time of sedimentation. The appearance of tourmaline within rip-up clasts, and in laminae within pebbles, is evidence of syngenetic introduction of boron.Three populations of tourmalines, on the basis of composition as determined by microprobe analyses, are described from the area:(1) A Proterozoic stock intruding the Aldridge Formation contains abundant schorl.(2) A tourmaline intermediate in composition between dravite and schorl is typical of Aldridge metasediments. Texturally this type occurs as (a) fine felted aggregates in the footwall of the Sullivan orebody, (b) disseminated through waste beds, and (c) in local concentrations removed from the Sullivan orebody.(3) Coarse-grained recrystallized tourmaline associated with the Sullivan ore is magnesium-rich. Recrystallization is erratic, and is probably related to uneven heat flow during metamorphism and to differences in bulk composition.The economic importance of tourmaline concentrations in the Aldridge Formation is their association in both space and time with stratiform sulfides.
Nitrogen and C/N ratios in the sediments of Lakes Superior, Huron, St. Clair, Erie, and Ontario
Authors: Kemp A. L. W. , Thomas R. L. , Wong H. K. T. , Johnston L. M.
Published: April 2011

The distribution of nitrogen (N) was determined on 1238 surface sediment samples (0–3 cm) and 24 cores from Lakes Superior, Huron, St. Clair, Erie, and Ontario. The concentration of N was greatest in the depositional basins of the lakes. The N concentrations decreased sharply from high values at the sediment–water interface to uniformly lower N values at the base of the cores. The surface enrichment was related to increased inputs of N to the lakes since settlement of the region in the order: Lake Ontario > Lake Erie [Formula: see text] Lake Superior > Lake Huron > Georgian Bay.The organic carbon: total nitrogen (C/N) ratios averaged 10.2 in the surface sediments with a range of 5.1 to 66.0. The lowest ratios were found in the depositional basins, with the exception of Lake St. Clair. The magnitude of the C/N ratios was related to the source of the organic matter. Plankton, which are the main source of Org-N in the lakes, accounted for C/N ratios between 7 and 9. Dilution of the modern sediment with organic matter from glacial deposits yielded the higher ratios and low Org-C contents in the nondepositional zones. The high C/N ratios and Org-C contents in Lake St. Clair were believed to be due to a large component of macrophytes in the inputs of organic matter to the lake sediments.
A new technique in neutron activation analysis of Na/K ratios of fluid inclusions and its application to the gold–quartz veins at the O'Brien mine, Quebec, Canada
Authors: Krupka K. M. , Ohmoto H. , Wickman F. E.
Published: April 2011

A new analytical technique which employs hydrated antimony pentoxide to selectively remove Na from Na–K–Cl mixed fluids was successfully tested. With this technique, the uncertainty in the K determination of inclusion fluids by neutron activation analyses can be reduced to less than ± 10% compared to greater than ± 20% uncertainty which is typical in the conventional techniques.Na/K ratios of fluid inclusions in 14 quartz samples from gold–quartz veins at the O'Brien mine. Quebec, Canada were determined using this technique. The Na/K atomic ratio of the samples ranges from 0.9 ± 0.1 to 24.3 ± 3.9. Optical examinations of the fluid inclusions indicate that the variation in the Na/K ratios is caused by the presence of varying proportions of four different types of fluid inclusions: type I (pregold mineralization fluids: CO2 rich), type II (gold mineralizing fluids showing evidence of boiling at temperatures of 380°–300 °C), type III (postgold mineralization fluids; vapor – liquid two phase inclusions), and type IV (postgold mineralization fluids; halite bearing), Type II fluid inclusions appear to have Na/K atomic ratios of approximately 1.0, while type IV inclusions show Na/K ratios of over 24.
Trace element geochemistry of a Precambrian diabase dike from western Ontario
Authors: Dostal J. , Fratta M.
Published: April 2011

A diabase dike of the Precambrian Mackenzie swarm from western Ontario has been sampled at two localities where it intrudes basaltic volcanics and granite respectively. The two profiles across the dike have rather similar contents of major and some trace elements (REE, U, Zr, Hf, Y, Nb, Sc, Co, Cr, and Sc) but differ in the abundances of K and related elements (Rb, Tl, Li, and Ba), which are significantly higher in the section of the dike intruding the granite. The differences can probably be attributed to selective contamination from granitic country rocks by diffusion.
Aborted Proterozoic rifting in eastern Newfoundland
Authors: Strong D. F. , O'Brien S. J. , Taylor S. W. , Strong P. G. , Wilton D. H.
Published: April 2011

Recent geological mapping and geochemical studies of the late Proterozoic rocks of the Burin Peninsula in the southwestern part of the Avalon Zone of Newfoundland show the following sequence: (1) The basal Rock Harbour Group, a sedimentary assemblage ranging from conglomerates to turbidites, was derived from a subaerial volcanic–plutonic source region. (2) The overlying Burin Group, a belt of mafic volcanic and intrusive rocks that have alkalic affinities at the base but are dominated by oceanic tholeiite. (3) The Marystown Group, a bimodal sequence of alkalic basalts and rhyolites deposited in a subaerial environment unconformably above the Burin Group, and apparently conformably overlain by Infracambrian to Cambrian sedimentary rocks. Stromatolites occur within resedimented limestone breccias and conglomerates at the top of the Rock Harbour Group and throughout the Burin Group.These assemblages are interpreted to indicate that after a period of continental type bimodal volcanism, the Avalon terrain was rifted in Burin Group times to form some kind of small ocean basin, which was abruptly closed with a reversion to continental type bimodal volcanism of the Marystown Group.
Teleseismic reflections and the Newfoundland lithosphere
Authors: Stewart Ian C. F.
Published: April 2011

Travel-time residuals for teleseismic PP waves reflected under Newfoundland are consistent with a crust towards the western edge of the Central Mobile Belt at least 10 km thicker than in adjacent regions. The thicker and faster crust probably overlies an area of the upper mantle that is up to about 0.5 km s−1 faster than normal for P waves, down to at least 100 km depth. The higher seismic velocities may be due to anisotropy in a former oceanic upper mantle. The low number of reflections observed from the eastern margin of the Mobile Belt could be due to asymmetry in the ray paths due to dipping structure, such as a fossil subduction zone, near the PP reflection point.
Mineralogy and petrology of the Sokoman Iron Formation near Ardua Lake, Quebec
Authors: Lesher Carl M.
Published: April 2011

The Proterozoic Sokoman Iron Formation near Ardua Lake, Quebec at the western edge of the Labrador Trough has undergone considerable diagenetic changes but probable only very low-grade metamorphic conditions. Locally, intense folding and thrust faulting are present. Comparisons have been made with the well-established stratigraphy of the relatively undeformed Sokoman Iron Formation in the Howells River area, 65 km along strike to the south of Ardua Lake.Representative assemblages for some of the members are as follows: quartz–chamosite–siderite–ankerite–K–spar–graphite±biotite±stilpnomelane (Ruth shale); chert–magnetite–siderite–talc±ankerite±stilpnomelane (Lower Iron Formation); chert–hematite–magnetite–talc–dolomite±riebeckite (Lower Red Cherty –Pink Grey Cherty); and chert–dolomite–magnetite–stilpnomelane±albite±hematite (Lean Chert). Although the assemblages may be strongly recrystallized, many of the original, sedimentary textural features and mineralogy have been preserved. Chert (and recrystallized quartz), hematite, magnetite, carbonates (calcite, manganoan siderite and manganoan dolomite) and possibly stilpnomelane are considered to be the recrystallization products of sedimentary precursors. Albite, chlorite and riebeckite are considered to be authigenic or diagenetic in origin; only biotite and members of the talc–minnesotaite series are considered to be reaction products of late diagenesis and subsequent very low-grade metamorphism.
Tidal loading in Nova Scotia: results from improved ocean tide models
Authors: Beaumont Christopher , Boutilier Ross
Published: April 2011

A re-examination of tilt and gravity observations from Nova Scotia in light of recent ocean tide studies confirms previous assertions that the M2 tide in the western North Atlantic Ocean is intermediate between the numerical models of Tiron, Sergeev, and Michurin, and of Zahel.Tilt calculations, using a new M2 ocean tide model, reinforce the conclusion that the crust beneath Nova Scotia is of a transitional type between oceanic and thickened continental and is more easily deformed than most other crustal types.The tilt observations are in poor agreement with the Jachens–Kuo model, JK25, of the O1 tide in the western North Atlantic Ocean. It is suggested that the gravity observations, from which JK25 was inferred, were subject to amplitude and phase calibration errors. These errors are estimated from a comparison with the M2 results.
Trend surface analysis of major late Wisconsinan till sheets, Brantford–Woodstock area, southern Ontario
Authors: Cowan W. R.
Published: April 2011

Linear and quadratic trend surfaces were computed for textural, carbonate, clast, and heavy mineral properties of the Catfish Creek (Nissouri Stadial), Port Stanley (Port Bruce Stadial), Tavistock (Port Bruce Stadial), and Wentworth (Port Huron Stadial) tills.Catfish Creek Till pebble grade material provided trend surfaces reflecting the underlying bedrock. However, an overall lack of regional trends in Catfish Creek Till is consistent with field observations that indicate remarkable uniformity for this till over several hundred square kilometres, a phenomenon that is believed to reflect the high energy of this ice sheet. Carbonates in Port Stanley Till were found to increase from east to west as the Silurian–Devonian contact was crossed. Tavistock Till was found to have increasing sand content and decreasing silt content from northwest to southeast owing to incorporation of underlying glaciofluvial sediments; pebble trends reflect the underlying bedrock for the most part. Wentworth Till trend surfaces for carbonates and pebbles show high dolomite near the Niagara Escarpment to the east and northeast with a dilution of dolomite and influx of limestone to the southwest.The strong relationship of the trend surfaces to substrate materials indicates the basal nature of the tills and the local origin of most glacial deposits. Pebble lithologies provide much information about local bedrock and drift prospectors should give close consideration to coarse fragments.
A Late-Quaternary pollen profile from Woodstock, Ontario
Authors: Mott R. J. , Farley-Gill L. D.
Published: April 2011

Maplehurst Lake, situated in a former interlobate zone that was deglaciated relatively early compared to adjacent areas of southern Ontario, provides one of the more complete pollen records for the region.Five radiocarbon dates allow determination of sedimentation rates and hence pollen influx rates. Both relative percentage and pollen influx values outline a vegetational history that began prior to 12 000 years BP with a herb pollen zone representative of tundra conditions. This was followed by invasion of spruce that culminated in a spruce woodland environment which peaked about 11 200 years BP and then declined, to be replaced, beginning about 9500 years BP, by a closed mixed conifer–hardwood forest dominated by pine species. Hemlock replaced pine as the most abundant coniferous species about 7200 years BP. Hardwoods completely dominated the forest after 6400 years BP and beech, maple, oak, elm, and ash were prominent, associated with a wide variety of other deciduous genera. The deciduous hardwood forest prevailed without major change until recent times when the forests were largely removed for agriculture. Ragweed, grasses, and other weed taxa indicative of agricultural activity characterize the pollen spectra of this most recent interval. This sequence of events parallels those found at sites throughout the Great Lakes region, New England, and Maritime Canada and adds to the knowledge of migration rates, succession, chronology, and climate of northeastern North America.
Stratigraphy, facies changes, and correlations in the northern Selkirk Mountains, southern Canadian Cordillera
Authors: Brown Richard L. , Tippett Clinton R. , Lane Larry S.
Published: April 2011

The Hadrynian Horsethief Creek Group that underlies much of the northern Selkirk Mountains is divided into three members. The upper pelitic member is overlain by latest Hadrynian to Lower Cambrian rocks of the Hamill Group and is correlated with the Yankee Belle Formation of the Cariboo Group in the Cariboo Mountains to the northwest. The underlying middle marble member is correlated with the Cunningham Formation, and the lowest exposed lower pelitic member with the Isaac Formation.Westward thickening of the Horsethief Creek Group is paralleled by a gradational change in the upper pelitic member from a predominantly clastic sequence to the east to a predominantly calcareous sequence to the west. The overlying Hamill Group also changes in character, becoming more pelitic and interdigitating with basaltic metavolcanics toward the west. These facies changes are compatible with results from adjacent areas that point to deposition on a continental shelf in late Proterozoic to early Paleozoic time.
On the statistics of grain size variation along a gravel river
Authors: Church Michael , Kellerhals Rolf
Published: April 2011

A suite of 78 samples of riverbed gravel obtained at 39 sites along a 140 km reach of Peace River was used in a statistical study of the behaviour of mean grain size downstream. Whilst the exponential decline described by Sternberg was found in the overall data, significant additional 'structure' was also present. Although efforts were made to ensure that a homogeneous set of samples was obtained in the field, large site scale variability in the data prevented the complete elucidation of the additional pattern, which is probably due to injection of new material at tributary junctions. The paper illustrates sampling criteria that must be met for adequate description of grain size variations along a gravel river and identifies constraints that may limit its achievement.
Potassium–argon ages of intrusion and scheelite mineralization, Cantung, Tungsten, Northwest Territories
Authors: Archibald Douglas A. , Clark Alan H. , Farrar Edward , Zaw U Khin
Published: April 2011

K–Ar dating of magmatic biotite, and of hydrothermal biotite and muscovite, demonstrates that quartz monzonite intrusion and exoskarn scheelite mineralization at Cantung, N.W.T., took place over a brief interval in the Upper Cretaceous (ca. 91 Ma). The regional age relationships of magmatic and ore-forming activity in the Logan–Mackenzie Mountains are poorly defined, but it is tentatively inferred that tungsten mineralization may have been related to a late stage in the plutonic development of the area.
A tooth of Mammuthus primigenius from Chestermere Lake near Calgary, Alberta, and the distribution of mammoths in southwestern Canada
Authors: Harington C. R. , Shackleton D. M.
Published: April 2011

A well-preserved molar of a woolly mammoth (Mammuthus primigenius) was recovered from deposits at Chestermere Lake near Calgary. It is probably of late Wisconsin age, and is one of several mammoth fossils collected from Pleistocene sediments in the Calgary area.The Chestermere Lake specimen is considered in relation to 94 records of mammoth cheek teeth from the western Canadian provinces. Of the 94 records, 5 are from Manitoba, 35 are from Saskatchewan, 37 are from Alberta, and 17 are from British Columbia. In addition to specimens of woolly mammoths, remains of Columbian (Mammuthus columbi), imperial (Mammuthus imperator), and southern mammoths (Mammuthus meridionalis) have been collected from Pleistocene deposits of southwestern Canada. Some problems concerning the relationships of North American and Eurasian mammoths are mentioned.
Time evolution of stress under an artificial lake and its implication for induced seismicity
Authors: Withers R. J. , Nyland E.
Published: April 2011

The time history of stress beneath a realistic artificial lake with a realistic loading history on a permeable lithosphere can be calculated by solving the consolidation equations for a uniform permeable medium. The evolution of stress conditions towards or away from a Mohr–Coulomb failure envelope illustrates that highest risk of induced seismicity exists at initial loading and in some cases after a down-draw of the lake. The calculated histories depend crucially on hydrologic and geologic conditions which are very poorly known at many artificial lakes. If the formation strengths are constant in the area of the lake, consolidation theory indicates that failure is most likely under the lake in strike-slip or normal fault regimes. If failure occurs due to loading on a thrust fault regime it will occur at an offset from the lake.