bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass flow deposits in a Quaternary succession near Ottawa, Canada: diagnostic criteria for subaqueous outwash
Authors: Rust Brian R.
Published: April 2011

Stratigraphic relationships indicate that late Quaternary outwash near Ottawa, Canada, was deposited close to the ice front and below wave base in the Champlain Sea and/or an earlier ice-dammed lake. Distinct sand and coarse gravel facies are present, the latter with clast long axes parallel to flow, indicating deposition from a high energy current with high clast concentration.The sand facies contain channels up to 10 m deep and 40 m wide, filled with essentially massive sand. In some cases the base and basal fill are contorted into ball-and-pillow structures, and the channels contain dish structures and scattered pebbles. Similar features occur in the channeled sands of deep sea submarine fan valleys, and are thought to indicate rapid deposition by a mass flow mechanism, with high sediment concentration and low turbulence. In the present case, deformation at the channel bases probably resulted from liquefaction due to rapid sediment loading; dewatering gave rise to dish structures at higher levels. Possible mechanisms for initiating mass flows include shock waves generated by iceberg calving, and the effects of rapid changes in water level and salinity as the Champlain Sea invaded the area.
Lower Devonian conodonts from the Karheen Formation, southeastern Alaska
Authors: Savage Norman M.
Published: April 2011

Conodonts from the eastern end of Heceta Island and from a small island of the Ham Island group in the Karheen Passage, southeastern Alaska, include Ozarkodina eberleini n. sp., Eognathodus sulcatus Philip, Pandorinellina exigua philipi (Klapper), Icriodus angustoides castilianus Carls, and Pelekysgnathus klamathensis Savage. Both localities are in the Karheen Formation. The age of the faunas is considered to be early Pragian (Faunal units 5 and 6 of Klapper et al.). The early form of Eognathodus sulcatus predominates in the Heceta Island collection from Locality 1, suggesting Fauna 5, and the late form predominates in the Ham Island collection from Locality 2, suggesting Fauna 6. A middle Early Devonian age for the faunas is significant in that Locality 1 is also USGS locality 2689 which previously has yielded brachiopod and coral faunas considered to be of Late Silurian age.
A model for recent plate interactions off Canada's west coast
Authors: Riddihough R. P.
Published: April 2011

Detailed re-examination of existing magnetic anomaly data reveals the fine structure of variations in spreading rates and directions at the Juan de Fuca and Explorer Ridges during the last 10 million years. A geometrical model using these variations delineates the theoretical history of the interactions between the lithospheric plates involved. These interactions demonstrate the independent movement of the Juan de Fuca and Explorer plates and the development of the Sovanco Fracture Zone. The latter was apparently initiated E–W at 7 Ma, rotated clockwise to 120° and may have been the site of up to 50 km of crustal shortening. The model demonstrates that subduction rates at the Canadian continental margin declined from 5 cm/yr to a present 1.5 cm/yr and that recent relative movements are compatible with the N–S compression observed from earthquakes. It also suggests that the existence of both E–W and NE trending faults in the downgoing lithosphere beneath Vancouver Island, shows that a triple junction remained static near the northern end of Vancouver Island from 10–4 Ma, and predicts a buried northern edge of subducted material striking NE in this area.
Les chitinozoaires de la zone à Dicellograptus complanatus Formation de Vauréal, Ordovicien supérieur, Ile d'Anticosti, Québec
Authors: Achab A.
Published: April 2011

Borehole samples from the Vaureal Formation (Upper Ordovician), Anticosti Island, Quebec contain well preserved assemblages of chitinozoans; in this paper the specimens found in the Dicellograptus complanatus zone are described.In addition to the new forms recorded, Cyathochitina vaurealensis n. sp. and C. anticostiensis n. sp., the assemblages are characterised by Acanthochitina barbata and Lagenochitina baltica, species which enable a correlation to be made between the Upper Ordovician (Upper Caradocian – Lower Ashgillian) of Europe.
Petrogenesis of the Boundary intrusions in the Flin Flon area of Saskatchewan and Manitoba
Authors: Syme Eric C. , Forester Richard W.
Published: April 2011

The Aphebian Boundary intrusions are a group of lensoid, ultramafic to felsic rocks which occur in a N–NW trending zone 10 km long by 4 km wide centred on the town of Flin Flon. The intrusions were emplaced into Amisk metavolcanic rocks and Missi metasedimentary rocks. Field relationships, petrography, and chemical characteristics of the Boundary intrusions indicate that they are composed of three compositionally distinct, sequentially emplaced groups. From oldest to youngest, these are (1) a mafic augite- and biotite-bearing mela-dioritic group, (2) a felsic group ranging from leucodiorite to granodiorite, and (3) an olivine-bearing (wehrlite to olivine gabbro) group. The mafic group crystallized at relatively high [Formula: see text] and [Formula: see text], such that successive differentiates have increasing MgO/FeO ratios. Molar ratio diagrams clearly indicate that fractionation of augite, minor magnetite, and possibly subordinate olivine can account for the observed chemical variation of approximately 80% of this group, whereas the olivine-bearing group could only have formed by crystal fractionation of subequal amounts of olivine and clinopyroxene, and minor magnetite. The felsic group is chemically similar to the post-Missi granodioritic plutons and cannot represent SiO2-rich residual liquids produced solely by fractionation of augite and olivine from a basaltic magma.
Magnetization of oceanic crustal layer 2—results and thoughts after DSDP Leg37
Authors: Ryall Patrick J. C. , Hall James M. , Clark J. , Milligan T.
Published: April 2011

The detailed study of 455 basement samples from DSDP Leg 37 reveals magnetic properties, particularly inclinations and intensities, different from those commonly considered representative of Layer 2. Non-dipole inclinations are the most common. The deepest hole (582 m) has a vector average intensity of 24.3 × 10−4 emu cm−3 (24.3 × 10−1 A/m) and an inclination of only −14.5°. Induced magnetization never dominates and is usually much less than remanent magnetization, with Q ratio averaging 35 for basalts and 2.6 for plutonic rocks. Viscous magnetization acquisition constant, S, ranges widely from 0.001 to 1 × 10−4 emu cm−3 (0.001 to 1 × 10−1A/m), but is very rarely sufficient to cause VRM to dominate NRM.The major carrier of NRM is cation-deficient titanomagnetite produced by low-temperature oxidation of stoichiometric titantomagnetite. There is no trend of alteration with depth. All the magnetic properties are controlled by conditions within the individual basalt pillows or more massive units. A high degree of cation deficiency is associated with reduced NRM intensity, initial susceptibility, saturation magnetization, and VRM acquisition and increased MDF, Q ratio, and Curie point. Zones of low cation deficiency are presently found only in parts of massive units. With the exception of rare individual samples pillow sequences are highly oxidized throughout.A discussion is given of the kinds of ocean crust drilling and laboratory experiments required to solve the problems of the magnetic structure of Layer 2 as seen at the Leg 37 sites.
Simulation of long-term changes in the magnetic signal of the oceanic crust
Authors: Dunlop David J. , Hale Christopher J.
Published: April 2011

We report magnetic properties of submarine basalts 3.5 to 16 Ma in age recovered from depths as great as 530 m in layer 2 near the Mid-Atlantic Ridge at 37° N during Leg 37 of the Deep Sea Drilling Project. The rocks are classified as type-I if they have reversible in-vacuum thermomagnetic curves and as type-Il if they are thermomagnetically irreversible and develop a high-Curie-point phase (believed to be magnetite) when heated. Initial Curie points are low: 140–200 °C in type-I rocks, 250–300 °C in type-II rocks. The phases responsible are thought to be stoichiometric and cation-deficient (oxidized) titanomagnetite, Fe2.4Ti0.6O4, respectively. Only the 3.5 Ma basalts contain any type-I material; the older basalts are completely oxidized.Viscous magnetization is uniformly strong in type-I rocks, weaker and variable in type-II rocks. Hysteresis properties explain this difference. It is not due primarily to the chemical difference between stoichiometric and oxidized titanomagnetites, but to a difference in grain size. Type-I rocks are magnetically very soft: the coercive force (Hc) is 15–90 Oe (1194–7162 A/m), the median demagnetizing field [Formula: see text] of natural remanent magnetization (NRM) is 35–135 Oe (2785–10743 A/m), the ratio between saturation remanence Jrs and saturation induced magnetization Js is generally [Formula: see text] and the ratio of remanent coercive force, HR, to Hc is [Formula: see text]. These results all indicate multidomain grains of titanomagnetite ≥ 40 μm in size. Opaques of this size are seen in polished thin sections. Type-II rocks have Hc > 150 Oe (11937 A/m), [Formula: see text] (27 853 A/m), [Formula: see text] and HR/Hc generally < 2, indicating single-domain or pseudo-single-domain behaviour in micron- or submicron-size grains. The small magnetic grain size in type-II rocks could result from preferential oxidation of fine grains and/or subdivision of larger grains by inhomogeneous oxidation. The pronounced viscous magnetization of type-I rocks is therefore thought to be due to coarse, unoxidized multidomain grains of titanomagnetite.Long-term viscous magnetization is simulated by measuring viscous decay curves at temperatures up to 200 °C. Relaxation times are strongly temperature dependent: relaxation times as long as 106 yr can be activated in laboratory experiments at 75 °C if a low-Curie-point phase like Fe2.4Ti0.6O4 carries the viscous magnetization, or at 200 °C if Fe3O4 is the carrier. Viscous remanent magnetization (VRM) over 106 years seems to be no more than a factor 2 or 3 times the VRM estimated by extrapolating room-temperature data determined over a laboratory time scale. Even in type-I rocks, long term VRM is insufficient to completely erase the NRM.
Concentration and composition of lead in DSDP Leg 37 cores
Authors: Yamaguchi M. , Russell R. D. , Slawson W. F.
Published: April 2011

The concentration of lead in 12 samples ranges from 0.58 ppm to 7.4 ppm. Eight of the samples contain less than 1 ppm of lead. Isotopic analysis of the 14 samples indicates a relatively uniform lead composition clustered about 206Pb/204Pb = 18.89, 207Pb/204Pb = 15.65, and 208Pb/204Pb = 38.50.
Uranium in oceanic rocks: DSDP Leg 37
Authors: Mitchell William S. , Aumento Fabrizio
Published: April 2011

Fission-track mapping of uranium concentrations in basalts recovered from Leg 37 of the Deep Sea Drilling Project indicates that secondary enrichment or redistribution of the element is confined to specific zones of altered basalt. Primary magmatic variation in uranium concentration corresponding to major and trace-element variation within the basalts can also be discerned. Uranium, strontium, and other trace element values for the basalts fall into two distinct groupings, providing clear indication that two separate magmas were involved in the formation of the upper oceanic crust at site 332. Different degrees of partial melting of upper mantle material is the most probable mode of formation of the two distinct magma sources, which were tapped repeatedly and alternately to form the observed sequence of basalts encountered during the drilling of hole 332B.
Acoustic velocities and electrical properties of frozen sandstones and shales
Authors: King M. S.
Published: April 2011

Ultrasonic velocities and electrical properties have been measured in the laboratory at permafrost temperatures on a number of samples of sandstones and a shale which had been recovered from boreholes in the arctic and stored in their natural frozen state. Compressional and shear-wave velocities, electrical resistivity, and phase-angle relationships in the frequency range 0.005–100 kHz have been measured on the permafrost samples, at temperatures in the range −18 °C–+4 °C.Results of the tests show that, at a particular temperature, there is a small decrease in the electrical resistivity measured on all samples tested as the frequency is increased. The phase-angle differences measured show no consistent relationship with either frequency or temperature, but they are all less than 12° in magnitude. The electrical resistivity at a particular frequency and the ultrasonic velocities are affected in a similar manner by changes in temperature. Whereas the sandstones show a sharp reduction in velocities and resistivity as the temperature is raised to 0 °C or above, the shale shows little dependence of these parameters on changes in temperature in the range tested. An increase in shale content of the sandstone results in behavior intermediate between that of a clean sandstone and that of a shale.
Synthetic seismograms and the response of an anisotropic attenuating medium
Authors: Sprenke K. F. , Kanasewich E. R.
Published: April 2011

The Haskell–Thomson matrix formulation has been modified to yield synthetic seismograms and theoretical spectral ratios in a system of parallel anisotropic lossy layers. Transfer function matrices are derived for the case of transverse isotropy with a unique vertical axis. Attenuation is included in the analysis through the use of complex elastic coefficients. Short period spectral ratios and time syntheses are found to be significantly affected by the presence of uniaxial anisotropy for a typical continental crustal model while long period spectral ratios are shown to be sensitive to anisotropy in the upper mantle. Normal values of Q for the crust produce almost no change in teleseismic spectral ratios at useful frequencies. Synthetic seismograms for a continental crust indicate that crustal reverberations of teleseismic impulses are attenuated within 5 s of onset
La position stratigraphique déterminée paléomagnétiquement de sédiments carbonifères de Minudie Point, Nouvelle Ecosse : à propos de l'horizon repère magnétique du Carbonifère
Authors: Roy J. L.
Published: April 2011

Chemical, thermal, and alternating field cleaning treatments indicate that the Minudie Point sedimentary beds acquired their initial magnetization slowly and progressively during a lengthy process that lasted from deposition to lithification. The magnetization carried by the pigment is separated vectorially from the magnetization acquired during the early phases and its direction is shown to be a reliable indicator of the direction of the magnetic field during lithification. The agreement between the directions of the magnetizations acquired at the beginning (175°, +15°; α95 = 6°; pole 122° E, 36° N) and at the end (172°, +20°; α95 = 5°; pole 125° E, 33° N) of the process indicates that the direction (irrespective of the sign) of the magnetic field remained virtually unchanged during the magnetization process. Slicing of specimens shows that certain apparently aberrant directions are in reality the directions of the resultant vectors of two magnetizations of opposite polarities.The recording of a normal polarity during the early phase of magnetization places these sediments below (and perhaps immediately below) the magnetic horizon marker at the base of the Permo – Upper Carboniferous interval of reversed polarity. This indicates that these beds which on geological evidence could be of Pictou or Riversdale age belong to the Riversdale Group. This result contributes to the pin-pointing of the stratigraphic position of the Carboniferous magnetic horizon marker which can be most useful for the study of the tectonic history of the ancient Carboniferous basin of eastern Canada. The study shows that this magnetic horizon marker is a valuable stratigraphic tool which can be used most effectively for global correlation of Carboniferous units.
New records of insect families from the freshwater Middle Eocene of British Columbia
Authors: Wilson Mark V. H.
Published: April 2011

New collections of Middle Eocene insects from seven localities in British Columbia include representatives of 17 families, in seven orders, bringing the total number of families recorded for the fauna to 31, distributed among 10 orders. The Mastotermitidae, Pentatomidae, Trichoptera, Sciaridae, Mycetophilidae, Syrphidae, and Vespidae are recorded from the fauna for the first time. The single specimens each of Syrphidae and Vespidae are among the oldest known of their respective taxa.Only one family, the Mastotermitidae, is not also known from either the Green River Formation or the Florissant Shales. The composition of fauna within British Columbia suggests age or environmental differences between the Horsefly and Princeton area localities, with the Driftwood Creek locality intermediate.
Fossils from the Dunnage Mélange, north-central Newfoundland
Authors: Hibbard James P. , Stouge S. , Skevington D.
Published: April 2011

Arenig conodonts and Tremadocian graptolites recovered from the Dunnage Mélange supplement previous fossil discoveries from the mélange and support the recent correlation of mélange lithologies with Exploits Group strata. The new fossil finds indicate that a block within the mélange is younger than portions of the matrix of this unit. This seemingly problematic relationship is resolvable in light of previous interpretations of a slump origin for the mélange as Tremadocian shales and Arenig carbonates were probably part of a pre-slump sedimentary–volcanic pile. The wide range in ages of fossils within the mélange is compatible with the interpretation that the mélange formed on a lower Paleozoic trench slope.
Ultramafic xenoliths from the Elwin Bay kimberlite: the first Canadian paleogeotherm
Authors: Mitchell Roger H.
Published: April 2011

Ultramafic xenoliths from the Elwin Bay kimberlite provide samples of the upper mantle beneath arctic Canada. The compositions of coexisting pyroxenes have been used to estimate the temperatures and pressures of equilibration of the three texturally and mineralogically distinct types of xenolith, i.e. spinel lherzolite (840–935 °C), coarse garnet lherzolite (925–1085 °C at 39.5–49.5 kbar (3.95–4.95 × 106 kPa)) and porphyroclastic garnet lherzolite (1090–1180 °C at 47.0–51.5 kbar (4.7–5.2 × 106 kPa)). The garnet lherzolite data define an inflected paleogeotherm whose upper limb lies at shallower depths than found for the Thaba Putsoa – Mothae paleogeotherm but which is identical to the Montana paleogeotherm. No evidence is found for iron enrichment of the upper mantle in this region.
P-wave residuals in Canada
Authors: Buchbinder G. , Poupinet G.
Published: April 2011

The aim of this study was to obtain station residuals for the Canadian network, hitherto unavailable, and relate them to tectonics across Canada, since Canada shows large variations in tectonics and has a uniform station net; 1692 short-period, vertical P-wave arrivals at the Canadian seismograph network from 82 events were reread and reduced to residuals with respect to the J–B tables. The epicentral distances of the data vary from 1° to 103°. The events occur mostly along the northern rim of the Pacific with a few sources in the Americas and Asia. For each event a baseline correction was determined and applied to the residuals. Station corrections and distance corrections for 2° intervals were obtained by the method of successive approximations which is shown to be a stable and convergent technique. Station corrections are found to decrease with tectonic age of the stations. In addition, for those stations in several tectonic provinces where heat-flow data exist, the station corrections increase with increasing heat flow. The residuals remaining after subtraction of the station and distance corrections exhibit a complex distribution that implies inhomogeneity in some source regions and beneath some parts of Canada.
Palaeoecology of marine Pleistocene Mollusca, Nova Scotia
Authors: Wagner Frances J. E.
Published: April 2011

Fossiliferous Pleistocene sediments are present in western mainland Nova Scotia and on Cape Breton Island. Two ages of deposits are represented: post-glacial in the Minas Basin area and mid-Wisconsinan in the Yarmouth–Digby area and Cape Breton. The mid-Wisconsinan age is based on both radiocarbon and U–Th dates. Molluscan assemblages indicate water temperatures colder than at present at the time of deposition of the post-glacial sediments, and comparable to the present for the older deposits. Assemblages from the Yarmouth–Digby area are compared with those of similar age from Tobaccolot Bay, Long Island, New York, and from Nantucket Island, Massachusetts. Foraminifera, previously unreported, were found in sediments of both ages.
Stratigraphy and sedimentology of Upper Silurian rocks, northern Somerset Island, Arctic Canada
Authors: Jones Brian , Dixon Owen A.
Published: April 2011

Late Silurian subtidal, interidal, and supratidal rocks are widely and complexly associated along the north coast of Somerset Island. The Read Bay Formation in the northwest, a subtidal limestone facies with brachiopod–coral faunas, is at least in part the lateral equivalent to the Leopold Formation in the northeast, the latter being an intertidal–supratidal facies of predominantly unfossiliferous dolomitic and sandy carbonate rocks. In intervening areas, the two fades intercalate widely, resulting in sections in which both subtidal and intertidal–supratidal sequences alternate repeatedly. The latter have been referred provisionally to the Read Bay Formation, although subsequent work may justify the designation of new lithostratigraphic units in the area of intercalation.The intertidal–supratidal rocks contain considerable quantities of texturally and mineralogically immature, sand-sized, detrital quartz, feldspar, and mica, apparently derived from nearby. The subtidal rocks also commonly contain large amounts (up to 50%) of clay- to silt-sized quartz, dolomite, muscovite, and clay minerals. The detrital sediment and the close association of subtidal and intertidal–supratidal rocks suggest that these Late Silurian rocks are part of a basin–margin succession flanking a low-lying land mass situated to the north and northeast. A general increase in the proportion of detrital sediment and greater persistence of near-shore carbonate facies toward the east suggest either greater proximity to a shoreline or a more persistently elevated land area in that direction.
Variation in lithology and tectonometamorphic relationships in the Precambrian basement of northern Saskatchewan
Authors: Lewry John F. , Sibbald Thomas I. I.
Published: April 2011

The southwestern part of the Precambrian Shield of northern Saskatchewan is divisible into five lithostructural domains. The lithological, structural, and metamorphic characters of these domains are described. The Mudjatik and Virgin River domains constitute parts of a more extensive mobile belt extending further east and share a common tectonometamorphic history. The western boundary of this (Hudsonian) mobile belt is marked by the Virgin River shear zone, a zone of repealed movement marked by a narrow belt of mylonite gneisses and sheared marginal granitic intrusions. To the west of the shear zone the Western Granulite and Firebag domains comprise elements of an earlier (Archean?)cratonic foreland, formed by granulite facies gneisses which are only mildly affected by later Hudsonian events. These two cratonic elements are separated by the Clearwater domain, a narrow mobile belt with a history broadly similar to that of the main mobile belt to the east.The Mudjatik and Virgin River domains are formed predominantly by granitoid gneisses, with supracrustal rocks appearing only in thin, often discontinuous zones. It is suggested that these relationships were achieved by remobilization of granitoid (Archean?) basement and preservation of the (Aphebian?) supracrustals between laterally moving, flat lying migmatite nappelobes.
Implications of coalification levels, Eureka Sound Formation, northeastern Arctic Canada
Authors: Bustin R. M. , Hills L. V. , Gunther P. R.
Published: April 2011

The rank of coal in the Eureka Sound Formation on Ellesmere and Axel Heiberg Islands ranges from brown coal to high volatile bituminous coal, based on reflectance determinations. Reflectance values from coals adjacent to the Stolz Fault, Axel Heiberg Island, are higher than in adjacent areas and may be related to abnormally high heat flows resulting from evaporite diapirism at depth, from the effect of overthrusting, or both. Regional reflectance values indicate that there is no correlation between the degree of coalification and the age of the strata, suggesting differing depths of burial and tectonic settings. Comparison of the coalification gradient at Fosheim Peninsula, Ellesmere Island, with that of the Téjon area of California permits estimation of a geothermal gradient which can be used for calculation of preorogenic sediment thickness. Maximum temperatures derived from the degree of coalification (100 °C at Fosheim) suggest that the sediments are within the zone of initial oil maturity.
Lead–zinc–barite veins of the Dorion Area, Thunder Bay District, Ontario
Authors: Franklin James M. , Mitchell Roger H.
Published: April 2011

The lead–zinc–barite deposits of the Dorion region are spatially associated with the unconformity between the Sibley Group (Helikian) and Archean and Aphebian basement rocks. The veins are coarse grained, and mineralogically zoned with galena–calcite in the central zone, sphalerite–quartz surrounding the central zone, and barite (±chalcopyrite) in the vein extremities. Veins occur near the pinch-out of the "Pass Lake formation" (basal Sibley Group), within the dolomite of the overlying "Rossport formation", or in nearby basement fractures. Rossport dolomite, where it forms a vein wall, is highly altered to metal-enriched chert and calcite. Archean wall rocks are not altered.Potassium–argon isotopic determinations on mica in Archean pegmatite immediately adjacent to a vein indicate that the transporting solutions were too cool to cause re-equilibration of the Ar within the mica. Sulphur-isotope data indicate equilibrium between galena and sphalerite yielding a depositional temperature range of 35–135 °C, and disequilibrium between sulphide–sulphate pairs. Lead isotopes are highly anomalous, yielding a secondary isochron which indicates either an Archean, or more probably a mixed Archean–Aphebian, source of lead.The deposits formed from metal leached from either basement rocks or breakdown of Sibley sandstone matrix. Metals and sulphate moved through the permeable sandstone, probably as chloride-ion complexes, and precipitated at the sandstone pinch-out. Reduced sulphur, possibly derived from organic decay, and probably held in a gas trap at the sandstone pinch out, caused precipitation of the sulphides by reaction with metal-bearing brines.
The age and upper boundary of the Nepean Formation in its type section near Ottawa, Ontario
Authors: Brand Uwe , Rust Brian R.
Published: April 2011

A sharp but conformable boundary with the overlying March Formation is present at the top of a section of the Nepean Formation near Ottawa, here proposed as the type section. The basal March unit can be recognized by its consistent and distinctly higher carbonate content (calcite and dolomite) than the underlying Nepean sandstones. The March and upper Nepean strata in this section contain a lower Arenigian conodont fauna, which can be correlated with similar faunas elsewhere in North America, and in Europe, Asia, and Australia. The Nepean–March contact is younger near Ottawa than around Brockville, indicating that the lower Ordovician succession represents a marine transgression, which progressed northward with time.
Paleomagnetism of Mesozoic plutons in the westernmost Coast Complex of British Columbia
Authors: Symons D. T. A.
Published: April 2011

The Lower Cretaceous Stephens Island (102 ± 8 Ma) and Captain Cove (109 ± 6 Ma) plutons and the Upper Jurassic Gil Island (136 ± 3 Ma) and Banks Island (144 ± 6 Ma) plutons belong to the western K–Ar age zone of the N 35° W trending Coast plutonic complex southwest of Prince Rupert, B.C. After removal of initial viscous components, AF demagnetization isolates a stable primary remanence at 36 of 49 sites (10 specimens from 5 cores/site) before anhysteretic components are added. All sites have normal polarity which is consistent because their K–Ar ages fall in the predominantly normal Cretaceous and Jurassic Quiet Intervals. The poles for Stephens Island (339° W, 67° N (7°, 10°)), Captain Cove (9° W 72° N (8°, 11°)), and Gil Island (357° N. 70° N (6°, 8°)) lie just north of Britain and are discordant for the North American craton. The tectonic panel including these plutons was tilted [Formula: see text] during the Upper Cretaceous–Paleocene orogeny as the leading edge of the North American plate overrode the subducting oceanic Kula Plate. This interpretation is supported by other arguments including the attitudes of contacts and foliations, plutonic trend directions, distribution of metamorphic grades, and paleomagnetic data from the area to the east. The Banks Island pluton lies in the tectonic panel to the west. Its pole of 210° W, 81° N (33°, 38°) is poorly defined but apparently concordant.
Stratigraphy of Georges Bank Basin: interpreted from seismic correlation to the western Scotian Shelf
Authors: Wade John A.
Published: April 2011

Based on the interpretation of reflection seismic profiles, five major reflecting horizons are correlated from the southwestern Scotian Shelf to Georges Bank. The Mesozoic–Cenozoic stratigraphy of Georges Bank Basin is interpreted to be similar to, but thicker than, the LaHave Platform and consists of 200 m of Tertiary and younger strata, 1000 m of Upper Cretaceous, 600 m of Lower Cretaceous, and 6300 m of Jurassic rocks. The post-Lower Cretaceous facies are interpreted to be clastic across the entire area, while the pre-Upper Cretaceous facies are interpreted to be predominantly clastic in the northern half and predominantly carbonates in the southern half of Georges Bank Basin.
U–Pb ages of some crystalline rocks from the Burlington Peninsula, Newfoundland, and implications for the age of Fleur de Lys metamorphism
Authors: Mattinson James M.
Published: April 2011

U–Pb measurements on minerals from the Burlington Peninsula indicate that volcanic rocks of the Grand Cove Group and the probably cogenetic Cape Brule porphyry have primary crystallization ages of 475 ± 10 Ma (Early Ordovician). Later intrusive rocks, including the Dunamagon granite, the Burlington granodiorite and the Seal Island Bight syenite were intruded between 445 and 435 Ma ago. The Grand Cove Group and the Cape Brule porphyry completely predate deformation and metamorphism of the eastern division of the Fleur de Lys Supergroup; the Seal Island Bight syenite, Burlington granodiorite, and Dunamagon granite were evidently emplaced during the early stages of this orogeny. The new age results therefore suggest that the orogeny is Taconic in the classic sense. Some of the isotope systems show evidence of a strong thermal event about 340 Ma ago (Early Carboniferous, Acadian). This event may have caused resetting of some of the Rb–Sr isochron ages recently reported for this area.
Mesozoic–Tertiary basin models for the Canadian Cordillera and their geological constraints
Authors: Eisbacher G. H.
Published: April 2011

Paleogeographic maps for the clastic successions of Early Jurassic, Late Jurassic – Early Cretaceous, and Late Cretaceous – early Tertiary time depict important geologic features that have to be considered in modelling of the Mesozoic sedimentary basins of the Canadian Cordillera. The relative positions of clastic basins, reverse fault zones, and volcanic complexes suggest that the crustal elements underlying the western Cordillera were foreshortened and thickened increasingly from early Mesozoic to early Tertiary. Throughout the late Mesozoic the Canadian Cordillera displayed subdued topography. Uplift was dramatic and possibly of Andean proportions during the latest Eocene and Oligocene. Reconstruction of paleogeography along major right-lateral faults suggests the possibility that old basement trends of the cratonic foreland may have had a profound influence on structures west of the Rocky Mountains. In terms of plate tectonics the Mesozoic basins of the Canadian Cordillera are marginal or possibly intra-arc basins, and cannot be compared easily with the presumed forearc basin containing the late Mesozoic Great Valley Sequence of California.
Magnetic model for the earth's crust under the Ukrainian Shield
Authors: Krutikhovskaya Z. A. , Pashkevich I. K.
Published: April 2011

A magnetic model for the crust under the Ukrainian Shield is proposed and the following aspects of its construction are discussed: (1) technique of separation of the regional component of the anomalous magnetic field; (2) estimation of rock magnetization and distribution of the sources of anomalies within the earth's crust; (3) Modelling of the crustal effect with the given distribution of magnetization; and (4) correlation of the regional component with crustal thickness and depth to Curie point isotherm of magnetite.Two ferromagnetic layers are established within the crust. Average magnetization of the upper crust ranges from 0.1 × 10−3 to 0.6 × 10−3 emu for different blocks. Magnetization maximum for the lower crust is 4 × 10−3 emu, the value being supported by different methods.Inhomogeneities with maximum magnetization of 6.5 × 10−3 emu are found within the lower crust.In the areas of regional highs the earth's crust is the thickest, the Moho discontinuity layered, and the distribution of magnetization anomalous for all depths.The stated correlation of regional component with crustal thickness may be of value in predicting the Moho topography.
Late Wisconsinan glacitectonic structures and evidence of postglacial permafrost in north-central Newfoundland
Authors: Eyles N.
Published: April 2011

Rhythmically-bedded glaciofluvial sediments deposited subaqueously and now exposed on an emerged coastal foreland in north-central Newfoundland, exhibit postdepositional deformation structures such as synclinal folds and faulted zones of ground collapse, the result of melting of underlying buried glacier ice. A high rate of glaciofluvial deposition is indicated. The development of fault systems in those sediments overlying decaying glacier ice can be compared with laboratory simulations of vertical foundering in sedimentary rocks. Ice-wedge casts transecting folded and faulted sections in the area are indisputable evidence of subsequent permafrost conditions, i.e. a period when mean annual air temperatures lay below −6 °C. A rise of at least 10.4 °C in mean annual air temperature is indicated since that time. A severe periglacial climate is considered to have existed in the area from 12 000 to 10 000 years BP and ice wedges developed with a minimum growth rate of 1.25 mm/year. Comparison with reports of ice-wedge casts in Nova Scotia and the west coast of Newfoundland indicate that the period which they formed in north-central Newfoundland may be correlated with the tundra pollen zone L-3 of Livingstone and Livingstone, the Greatlakian substage of the Lake Wisconsinan in Midcontinental North America.
Lower Devonian conodonts from Port St. Nicholas, southeastern Alaska
Authors: Savage Norman M. , Churkin Jr. Michael , Eberlein G. Donald
Published: April 2011

Conodonts from a limestone interval exposed above Port St. Nicholas, Prince of Wales Island, southeastern Alaska, include Pandorinellina exigua philipi (Klapper), Eognathodus sulcatus Philip, and Pelekysgnathus serratus Jentzsch. These conodonts indicate an early to middle Pragian age (informal faunal units 5 or 6 of Klapper et al). This middle Early Devonian age is supported by the presence of the graptolites Monograptus yukonensis, M. craigensis, and M. pacificus in shales above the limestone and by some shelly fossils from within the limestone.
An isolated ichthyosaur coracoid from the Maastrichtian of New Jersey
Authors: McGowan C.
Published: April 2011

An isolated ichthyosaur coracoid from the Hornerstown Formation of New Jersey extends the geological range of the Ichthyosauria at least to the late Maastrichtian. The specimen cannot be referred to any known taxon but is too incomplete to be described as the type of a new species.
Three statistical tests for 'goodness of fit'
Authors: Miller H. G.
Published: April 2011

A set of three statistical tests can be applied to all geophysical modelling techniques to objectively determine the 'goodness of fit' between the observed and modelled data. The three tests examine the mean, the standard error and the number of runs in the data defining the error function and they accept or reject the model on the basis of standard statistical tests on these three measures. The application of these tests to automatic, interactive or user controlled modelling procedures provides an objective and consistent set of criteria for accepting or rejecting a model on statistical grounds.
Shear phenomena in ice-thrust gravels, central Alberta
Authors: Babcock E. A. , Fenton M. M. , Andriashek L. D.
Published: April 2011

Pressures exerted by the continental ice sheet produced sheared zones and a pervasive crushing of strong quartzite clasts in preglacial Saskatchewan Gravels of central Alberta. Where deformation is of moderate intensity clasts have fractured at points of impingement with other clasts, and clasts of 3–6 cm in the longest dimension are most likely to be shattered. In zones of intense shear nearly all clasts larger than coarse sand have been crushed and drawn out into lensoid masses.An index of fracturing was devised to measure the degree of ice pressure induced deformation where the gravels show no evidence of having been disturbed. A model that defines possible conditions at the time of deformation is presented.
Hot water drilling in a cold glacier
Authors: Napoléoni Jean-Gérard P. , Clarke Garry K. C.
Published: April 2011

An open circuit hot water drill using a propane water heater and a gasoline-driven pump is described. The drill is designed to reach depths of 300 m in cold ice for holes with a minimum diameter of 3 cm.A maximum drilling rate of 120 m/h was obtained during field tests, and a 220 m hole was drilled in 4 h.
Multicomponent magnetization of the Pearson Formation (Great Slave Supergroup, N.W.T.) and the Coronation loop
Authors: McGlynn J. C. , Irving E.
Published: April 2011

The Pearson Formation is the youngest unit of the Great Slave Supergroup of the Coronation Geosyncline. Study of samples from 22 locations shows that the dominant magnetization has a direction 329°, −08° (α95 = 10°) and corresponding pole at 195°, 077°W (A95 = 9°). This magnetization is considered to have been acquired at the time the rock was formed about −1800 Ma ago. In addition, there are two, possibly three, overprints. One of the two well-established overprints is attributed to uplift following deep burial at about −1600 Ma. The other has no known explanation. These results, together with others from the Coronation Geosyncline, are used to construct a polar loop (the Coronation loop) that is apparently the paleomagnetic signature of the orogeny that affected the geosyncline. The Coronation loop straddles the boundary between the Aphebian and Paleohelikian, and it is tentatively suggested that the physical boundary between these two eras could be placed between the Great Slave Supergroup and the overlying Et-Then Group.
The distribution and thickness of icy permafrost in northeastern British Columbia
Authors: Crampton C. B.
Published: April 2011

The depth of icy permafrost below the active layer in northeastern British Columbia has been mapped in subparallel north-northwest and south-southeast zones, the thickest permafrost occurring in organic terrain near the Alberta border. Across the Rocky Mountain foothills in the west of the study area organic terrain does not contain icy permafrost, and permafrost occurs only on gentle northeast facing slopes. Slopes are the lands most sensitive to damage from line clearance operations, and the thawing of any icy permafrost present in the substrate increases erosion by water intercepted from the natural drainage, especially by warm pipelines. The water needs to be redirected back into the natural drainage systems.
Pétrologie des niveaux trondhjémitiques de haute pression associés aux éclogites et amphibolites des complexes leptyno-amphiboliques du Massif Central français
Authors: Nicollet C. , Leyreloup A.
Published: April 2011

High pressure trondhjemitic rocks interbedded with eclogites and high pressure amphibolites have been recognized in the leptyno-amphibolitic series of the Rouergue and Marvejols metamorphic terranes. These rocks appear to have been derived by partial melting of the surrounding amphibolites (or amphibole-gabbro) at [Formula: see text] (<7 × 105 kPa). The initial mineral assemblage of these layers (Q, Pl, Ky, Ga, Zo, etc.) is suggested by microstructural evidence to have crystallized directly under high pressure granulite facies conditions (12.5 kbar <PT <20 kbar (12.5 × 105 kPa < PT <20 × 105 kPa); 750 °C<T<840 °C) from the trondhjemitic liquid. The partial melting has taken place before the well-known Barrovian metamorphism that has affected the whole crystalline basement of the French Massif Central. This older metamorphic event is considered to be equivalent to the high pressure granulite facies metamorphism recognized in the Variscan of Europe. This acid–basic high pressure bimodal association argues for a close similarity between Archean greenstone belts and the leptyno-amphibolitic series.
Sedimentation processes and patterns in a glacier-fed lake with low sediment input
Authors: Smith Norman D.
Published: April 2011

Hector Lake, situated in the eastern Rocky Mountains of western Alberta, is fed primarily by nival and glacial meltwater. During summer when the lake is thermally stratified, inflowing water and fine sediment enter the lake as overflows and shallow interflows that are transformed into complex, but mostly downlake, epilimnial currents generated by downlake katabatic winds. Coriolis deflections produce a strong right-hand tendency in sedimentation patterns, with resulting crosslake (south-to-north) as well as downlake (west-to-east) proximal–distal trends: reduction in grain size, sedimentation rates, total carbonate, dolomite/(dolomite + calcite) and varve thickness.Laminae in bottom sediments are produced by inflow variations that are largely dependent upon air temperature. Five orders of inflow, and thus sediment input, variation capable of producing laminae are recognized: diurnal, subseasonal (short-term weather changes), seasonal (nival melt vs. glacial melt), annual and exceptional inflow events. Based upon laminae character, four facies of glacier-derived and one of non-glacier-derived bottom sediments are recognized in Hector Lake.
Geochemistry of zinc, copper and lead in the sediments of the estuary and Gulf of St. Lawrence
Authors: Loring D. H.
Published: April 2011

Total elemental concentrations (Zn, 8–215 ppm; Cu, 3–76 ppm; Pb, 9–66 ppm) vary texturally and regionally in the sediments of the St. Lawrence estuary and open Gulf of St. Lawrence.Chemical and mineralogical analyses indicate that 8–39% of the total Zn, 7–20% of the total Cu and 15–26% of the total Pb are weakly held by fine-grained organic material, oxide grain coatings, ion exchange positions and carbonates in the sediments. These concentrations are potentially available to the biota. The remaining concentrations (61–93% of the total) are not readily available but are locked up in fine-grained sulphide, oxide and silicate minerals.The highest concentrations of the detrital and non-detrital contributions occur in the pelites or muds of the upper estuary. Seaward these concentrations decrease as the natural and anthropogenic supply of dissolved and suspended particulate matter from the St. Lawrence River diminishes. The upper estuary acts as a sink for these elements because most of the non-detrital Zn, Pb and Cu supplied are removed here by adsorption onto fine-grained suspended terrestrial organic material from solution or before entry (Cu) and transferred to the bottom along with other fine-grained material in response to the present depositional conditions. Decreasing concentrations of these elements are deposited seaward and the sedimentation intensities of the non-detrital elements remain constant with fluctuations in total sedimentation intensity in the lower estuary and open Gulf of St. Lawrence.Biogeochemically, Zn is a contaminant and Pb and Cu are potential contaminants of the upper estuary sediments. Zn and Pb are potential contaminants in the lower estuary but all the elements are at or near natural levels in the open gulf sediments.
Tertiary basalts of western Davis Strait: bedrock core samples and geophysical data
Authors: MacLean B. , Falconer R. K. H. , Clarke D. B.
Published: April 2011

Short bedrock cores of basalt were recovered at two localities on the Baffin Island shelf, 33 and 89 km southeast of Cape Dyer. The volcanic rocks underlying these sites have a surface extent of some 8000 km2 as outlined by seismic reflection and magnetic anomaly profiles. Similar rocks are inferred to occur at two smaller offshore areas south of the main area. The offshore occurrences are both more continuous and much larger than the onshore basalt areas of eastern Baffin Island.The core samples appear to have been cut from single flows consisting of fine-grained microporphyritic basalts with olivine as the principal phenocryst phase. Although having distinct differences from one another in terms of texture and degree of alteration, the samples from the three drill stations bear similarities to the Baffin Island basalts that suggest a close petrogenetic relationship may exist between the onshore and offshore basalts. However, in contrast to the subaqueously erupted volcanic breccias of onshore Baffin Island and West Greenland the offshore samples contain little evidence of glass, suggesting the possibility that the latter may have been erupted in a subaerial environment.