bluuebunny/crossref_metadata_2025 huggingface dataset:
Les acritarches de la Formation d'Awantjish (Llandoverien supérieur) du sondage Val Brillant, Vallée de la Matapédia, Québec
Authors: Achab A.
Published: April 2011

not available
Physical and elastic properties of some khondalites from the Eastern Ghat Belt of Peninsular India
Authors: Gogte B. S. , Ramana Y. V.
Published: April 2011

Khondalites, which form an important rock suite of the Eastern Ghats, are studied for their physical and elastic properties together with their petrology and petrochemistry. Garnetiferous quartzites exhibit compressional and shear wave velocities between 4.9–5.6 km/s and 2–3 km/s; these are higher than garnet sillimanite gneisses, which are between 3.4–5.2 km/s and 1.4–2.6 km/s, respectively. The latter are more anisotropic than the former. Velocity and anisotropy are affected by alteration of garnet and sillimanite in these rocks. The velocities show a decreasing tendency with increasing manganese oxide. Garnetiferous quartzites bear a higher fracture strength than garnet sillimanite gneisses. Elastic wave velocity studies under hydrostatic pres sure to 5 kbar indicate slight changes with increasing pressure; and the absence of kyanite and the presence of cordierite in negligible amounts suggest their formation near the low to intermediate pressure granulite field.
Sedimentary structures and paleocurrents in a Tertiary deltaic succession, northern Banks Basin, Arctic Canada
Authors: Miall Andrew D.
Published: April 2011

The Eureka Sound Formation of northern Banks Basin is a deltaic unit of Paleocene to Eocene age. A basal member of shale, approximately 100 m thick, passes vertically and, in part, laterally into a succession of sand, silt, shale, and lignitic coal approximately 1000 m thick, which is referred to as the cyclic member because of the abundance of coarsening-upward cycles, averaging 7.4 m in thickness.Sand beds in the cyclic member can be divided into four lithofacies: (1) A facires dominated by medium- to large-scale planar crossbedding, formed by channel processes, including lateral point bar accretion, in the delta plain environment. (2) A predominance of medium-scale trough and (minor) planar crossbeds, formed by migrating dunes in distributary mouth bar sands. (3) A predominance of small-scale ripple-marks, formed by low energy, unimodal currents in distal distributary mouth sands. (4) A lack of current structures, indicating quiet-water, interdeltaic and prodeltaic deposition. The distribution of these four facies outlines a series of small lobate deltas.Paleocurrent data suggest a pattern of radiating distributaries within each delta lobe. Directional variance, when analyzed at various levels of the sedimentary structure hierarchy, provides information regarding channel sinuosity and enables comparisons to be made with other deltaic deposits. High variance for the directions of the distributaries is consistent with a fluvially dominated delta.
Preserved colour patterns in Ormoceras westonense from the Middle Ordovician of Quebec
Authors: Kobluk David R. , Hall Russell L.
Published: April 2011

Colour patterns preserved on specimens of the actinocerid Ormoceras westonense (Foerste) from the Montreal Formation (Caradocian) consist of longitudinal bands that probably occurred over the entire conch but varied in width and spacing around the circumference.
An edentulous frog (Theatonius lancensis, new genus and species) from the Upper Cretaceous Lance Formation of Wyoming
Authors: Fox Richard C.
Published: April 2011

A new genus and species of edentulous frog, Theatonius lancensis, from the Upper Cretaceous Lance Formation, Wyoming, is described. In addition to possessing an edentate maxilla, T. lancensis has a characteristic beaded ornamentation on known bones of the dermal skull. Familial relationships of T. lancensis are uncertain.
18O/16O and D/H studies along a 500 km traverse across the Coast Range batholith and its country rocks, central British Columbia
Authors: Magaritz Mordeckai , Taylor Jr. Hugh P.
Published: April 2011

Early Tertiary and Mesozoic ground waters in British Columbia were low in δ18O and δD, making it easy to document interactions of meteoric-hydrothermal H2O with the Coast Range plutons. The isotopic data on the igneous rocks can be grouped as follows:[Formula: see text]Zone I represents the gneissic migmatite core of the batholith, west of the quartz-diorite line. Zone II is the granodioritic eastern part of the batholith, and Zone III is a broad zone that includes the Jurassic Topley intrusions and extends from the eastern edge of the batholith to the Pinchi fault zone. Only in Zone I are isotopically 'normal' plutonic rocks found, and even there small amounts of meteoric water were apparently responsible for the late sericitization. All of the rocks in Zones II and III underwent widespread interaction with hot meteoric H2O, including the volcanic and sedimentary country rocks which have δD = −113 to −167 and δ18O = 1.9 to 10.8. Values of δD biotite < −140 are found in essentially all of the low-18O rocks, as well as in those that have 18O-zoned quartz or high Δ18Oqz–feld. Dike rocks have δD similar to their host rocks, but are typically lower in 18O (has the finer grain size facilitated exchange?). The batholithic intrusions apparently created gigantic meteoric-H2O circulation systems, larger than has heretofore been documented. The calculated δD of the H2O is −120 ± 20 assuming T = 500 to 200 °C, indicating that about 45–55 m.y. ago, the meteoric H2O had a uniform δD throughout the area. However, samples from the 140 m.y. old Topley intrusions suggest more D-rich waters, perhaps indicating a warmer climate in the Jurassic. These higher-temperature meteoric-hydrothermal effects are not found east of Pinchi Lake, a terrane that includes the Permian Cache Creek formation and various sediments, volcanic rocks, and blueschists that have δD = −65 to −117 and δ18O = 13.5 to 28.4. This area lacks igneous intrusions, so the meteoric H2O interactions in this area occurred at much lower temperatures than in Zones II and III (≈ 100 °C). Only the finest-grained rocks underwent partial D/H exchange with the meteoric waters responsible for local silicification, serpentinization, and vein carbonate deposition.
A new species of talpid insectivore from the Miocene of Saskatchewan
Authors: Russell Loris S.
Published: April 2011

Domninoides storeri, n.sp., is based on mandibular rami with teeth from the Upper Miocene Wood Mountain Formation at the Kleinfelder Farm locality near Rockglen, Saskatchewan. It has four premolars, of which P1, and P3 are single-rooted, P2 and P4 double-rooted, with P2 set obliquely on the jaw. There is a small metastylid on M2 and M3, but the crista oblique terminates separately, near the summit of the metaconid. D. storeri can be distinguished from other species of the genus in the Lower and Upper Miocene and Lower Pliocene of the western United States.
Magnetic, physical, and lithologic properties and age of till exposed along the east coast of Lake Huron, Ontario
Authors: Gravenor C. P. , Stupavsky M.
Published: April 2011

Oriented blocks of till from 31 sites were obtained from the Late Wisconsin St. Joseph Till over a distance of about 208 km along the east coast of Lake Huron. An analysis of paleomagnetic remanence data shows that two units within the St. Joseph Till were sampled, although it has not been possible to find a consistent stratigraphic break from field examinations. These two units give separate virtual geomagnetic pole (VGP) positions of lat. 67.1 °N, long. 297.8 °W and lat. 65.1 °N, long. 220.6 °W. Remanence data from varved clays for the Walkerton area, which were deposited at about the same time as the St. Joseph Till, gave a VGP position close to the mean of all remanence results from the St. Joseph Till. A spruce log extracted from the till was dated at 13 100 ± 110 y B.P. (GSC-2213), which is consistent with the time of the Port Huron ice advance.Granulometric analysis, carbonate analysis, and pebble analysis showed variations which are directly related to the nature of the underlying bedrock and could not be used to differentiate the two till units. Ratios of purple (dark red) to white (light red) garnets also demonstrate the presence of two till units within the St. Joseph Till and thus support the interpretation of the remanence data.The results show that in the absence of direct field evidence remanence data is a sensitive tool which can be used to determine if more than one till unit is present.
Silicified lignite from the Tertiary of south-central Saskatchewan
Authors: Broughton Paul L.
Published: April 2011

Silicified lignite erratics were collected from several localities in the Wood Mountain uplands of south-central Saskatchewan. The silicified debris is predominantly compressed stems and bladed grasses with micro-strandline accumulations of finely divided carbonaceous particles liberated from the lignite during silicification.The silicified lignite specimens have not been observed in situ, but are associated with exposures of Tertiary formations. The identification of the source strata is problematic.
The internal fabric of an alpine peridotite near Pinchi Lake, central British Columbia
Authors: Ross John V.
Published: April 2011

Near Pinchi Lake, central British Columbia, a fault-bounded alpine peridotite occurs within the Cache Creek Group. It comprises massive harzburgite, dunite, and pyroxenite, all of which display tectonite fabrics. Near isoclinal folds (F1), outlined by dunite, pyroxenite, and spinel layers (compositional layering) constitute the earliest recognizable penetrative deformation. A second set of near-coaxial open folds (F2) refolds the earlier set; both are cut by a later fracture cleavage (F3). Flattened, elongate olivine and orthopyroxene grains within the harzburgite outline foliations and lineations parallel with axial surfaces and minor fold axes of both fold sets. Narrow zones of mylonitization within the isoclinally folded dunites transect the composition layering, are parallel with the axial surfaces of the F1 isoclines, and appear to be related to refolding of F1 by F2. Relic olivines are kinked along {OKL}:[100], have pronounced α-maxima perpendicular to F1 and γ-axes maxima parallel to fold axis L1. Orthopyroxene, kinked on (100):[001] shows weaker fabric, but is symmetric with earliest composition layering, some 15°–20° away from F1. Asymmetry of fabrics results from olivine recrystallizing under conditions where orthopyroxene only kinks.It is speculated that the peridotite is a fragment of Paleozoic oceanic lithosphere. F1 and F2 are believed to be mantle transport fabrics resulting from a northerly driven plate, whereas F3 fractures are high-level emplacement features produced during late Paleozoic time.
Applications of geophysical techniques in permafrost regions
Authors: Scott W. J. , Hunter J. A.
Published: April 2011

This paper reports the results of some recent geophysical experiments carried out in the Arctic with a variety of methods. In the Beaufort Sea, seismic refraction profiles obtained with both source and receivers on the seabottom indicate the presence of discontinuous near-bottom high-velocity (4200 m/s) material interpreted to be presently aggrading permafrost. Spring-time resistivity soundings taken through the ice in Kugmallit Bay, Beaufort Sea, show the top of permafrost at about 50 m below the bottom. Even for 5-km spreads, the base of permafrost was not observed.Off the southeast coast of Melville Island, refraction seismic profiles shot on the seabottom and resistivity soundings made through summer ice yielded data which correlate with known sub-bottom geology, but which gave no clear indication of either presence or absence of permafrost.Seismic and resistivity measurements made at a number of control sites in the Arctic Islands yielded typical velocities of 3500 m/s and resistivities of 1 × 106 ohm-m for ice-saturated sands. Some correlation was observed between seismic velocity and moisture contents in the range from 10% to 40%.Seismic and resistivity results in IOL Lake at the Involuted Hill test site, Tuktoyaktuk Peninsula, suggest the absence of permafrost under some parts of the lake bottom. On the hill itself, seismic up-hole shooting and VLF resistivity profiling give interpretations of ice distribution which correlate well with drill control. Gamma-gamma logs taken in some of the drill holes correlate well with ice content logged during drilling.
Density and magnetic susceptibility measurements in southeastern New Brunswick
Authors: Gupta V. K. , Burke K. B. S.
Published: April 2011

The results of over 200 density and 400 (at 37 sites) in-situ magnetic susceptibility measurements from southeastern New Brunswick are presented. Intrusive rocks were found to be homogeneous in density and to have values similar to those reported from adjacent areas of the Northern Appalachians. However, most of the Coldbrook volcanic rocks show considerable variability in density values even within individual rock types. As expected, rocks containing higher proportions of ferromagnesian minerals (i.e., basalt, diorite, and gabbro) generally gave higher magnetic susceptibility values. The lack of aeromagnetic anomalies over mafic volcanic rocks in the central Caledonia Highlands may possibly be explained in terms of thin and flat-lying flow units.
Carpocrinus (Echinodermata: Crinoidea) from the Late Silurian of Somerset Island, Northwest Territories, Canada
Authors: Frest T. J. , Strimple H. L.
Published: April 2011

Carpocrinus arcticus n. sp. is the first Silurian crinoid to be reported from Arctic Canada (Read Bay Formation, Somerset Island). The species is distinguished from other North American Carpocrinus by its nonlobate calyx, plates with impressed sutures, and granular plate ornamentation. It is a member of a largely European lineage not previously reported from North America. The typical North American lineage was considered a separate genus (Stiptocrinus) by Kirk: it is here considered synonymous with Carpocrinus. Review of the stratigraphic distribution of Carpocrinus occurrences indicates that the lineage including C. arcticus is characteristic of Late Wenlock-Ludlow rocks.
Geologic interpretation of magnetic and gravity anomalies in the Strait of Juan de Fuca, U.S.–Canada
Authors: MacLeod N. S. , Tiffin D. L. , Snavely Jr. P. D. , Currie R. G.
Published: April 2011

A gravity and magnetic survey of the Strait of Juan de Fuca and adjacent Pacific continental shelf was conducted to define the tectonic framework in this 20 to 35 km wide seaway and its relation to that of Vancouver Island and the Olympic Peninsula. The offshore extensions of large onshore faults are delineated by linear magnetic and gravity anomalies. One of these, the Leech River fault of southern Vancouver Island, marks the northern limit of oceanic-type basaltic basement present in western Washington and Oregon. This fault probably continues southeast-ward from Vancouver Island across the strait to near the northeastern coast of the Olympic Peninsula, and westward across the strait to the continental shelf off Cape Flattery. The Calawah fault, which extends northwestward from near Cape Flattery onto the Pacific shelf, terminates the Leech River fault. Northwest of the Leech River fault on the shelf, the Calawah fault probably is the contact between oceanic and continental crustal types. The gravity and magnetic data also indicate the location of folds, other faults, and areas of shallow basement rocks.
Geomagnetic depth sounding and magnetotelluric results from a seismically active region northeast of Quebec City
Authors: Honkura Y. , Kurtz R. D. , Niblett E. R.
Published: April 2011

Observations of geomagnetic and telluric field variations have been made at four stations near La Malbaie, Quebec, in a seismically active region northeast of Quebec City. The data were analysed by transfer function and impedance tensor methods to study the nature of geomagnetic induction in the region and its structural implications. Transfer functions and telluric fields were influenced by several factors including the nearby St. Lawrence River, lateral variations in conductivity caused by geological complexities, and conduction of electric currents probably originating through induction in the ocean.It is demonstrated that it is possible to distinguish between induction by the vertical geomagnetic field and induction by the horizontal components. Anomalous vertical fields caused by vertical field induction are observed in the area and the electric currents associated with them have a flow pattern which is similar to that of currents induced by the horizontal field. Further, the Z-induced currents changed impedance tensor elements by as much as 20% though the effect was usually smaller than this. Nonetheless, the magnetotelluric data confirmed the presence of a conductivity anomaly in the Laurentides Park region of Quebec.
Removal of atmospheric argon contamination and the use and misuse of the K–Ar isochron method
Authors: Hayatsu A. , Carmichael C. M.
Published: April 2011

Crushed and homogenized aliquots of samples of basalt and diabase were analysed for 36Ar after various storage times, baking temperatures, and baking times. Il has been found that samples with panicle size greater than 100 mesh, and freshly crushed or stored in vacuum can be baked under vacuum to remove atmospheric argon contamination without loss of radiogenic argon. Using such procedures, initial 36Ar content can be determined uniquely and reproducibly. With removal of atmospheric argon contamination it is thus possible to apply the 40Ar/36Ar vs. 40K/36Ar isochron technique to K–Ar dating in a way exactly analogous to its use in Rb–Sr dating. An attempt is made to clarify some of the causes of misunderstanding that have contributed to improper use of K–Ar isochrons and to set out some of the advantages of the proper use of the method.
Determination of permafrost thickness in wells in northern Canada
Authors: Hnatiuk J. , Randall A. G.
Published: April 2011

Accurate interpretation of geophysical data, design of safe casing strings for drilling and production operations, and determination of the potential for existence of gas hydrates in and immediately below the permafrost zone are only possible if the thickness of the permafrost zone can be accurately determined.Freezing of interstitial water in soils has little effect on many of the physical properties of the soil, however, large changes in elastic properties and electrical resistivity do result. This makes it feasible to determine the thickness of the permafrost zone using techniques which measure changes in acoustic and electrical properties of the soils adjacent to the wellbore. This paper discusses the characteristic response which occurs as the borehole logging tool passes upwards from unfrozen sediments into the permafrost zone. It is this response which indicates the base of the permafrost zone and allows determination of permafrost thickness.Conclusive evidence of permafrost thickness and confirmation of permafrost thickness inferred from acoustic and electrical data is obtained from temperature data obtained subsequent to well suspension. Techniques utilized to obtain these temperature data are outlined in this paper.
The influence of wind, fetch, and water depth on the distribution of sediments in Lake Vänern, Sweden
Authors: Håkanson Lars
Published: April 2011

The purpose of this work is to establish an erosion–transportation–accumulation diagram for fine recent deposits on lake bottoms and to show empirically that an understanding of the bottom dynamic processes is of vital importance for a proper interpretation of sediment data.The potential maximum effective fetch (PFeff) has been used to indicate the available water energy, and the water depth has been used to indicate the effectiveness of the PFeff on the bottom. The 50% water content of surficial sediments, 0–1 cm, has been utilized as a physical sediment parameter to distinguish erosion from transportation and the 75% water content to separate transportation from accumulation.Relationships between water content, bulk density, and grain size are discussed.The distribution pattern of different elements (Be, B, V, Ni, Cu, Zn, Mo, Ag, Cd, Sn, Hg, Pb, Bi, P, and N) in the sediments of Lake Vänern is interpreted in the light of the bottom dynamic processes.
Détermination de la géométrie et des propriétés physiques du pergélisol discontinu de la région de Schefferville
Authors: K.-Seguin Maurice
Published: April 2011

The various parameters used to predict on a regional scale the lateral and vertical extension of permafrost are the following: surface temperature, thermal conductivity of rocks, and geothermal flow configuration. Locally this type of data is generally not sufficient and far too inaccurate. The use of geophysical methods at the surface and in boreholes in addition to existing thermal data helps to improve the degree of accuracy in the prediction of spatial distribution of permafrost in a given area. These geophysical methods include seismic refraction, electrical resistivity, and spontaneous and induced polarizations.Because of the properties of permafrost, seismic refraction at surface is useful only to determine the top of the permafrost whereas electrical resistivity (electric logging near surface) allows the determination of the upper and lower limits of permafrost. Seismic refraction, resistivity, and spontaneous and induced polarizations in boreholes were deemed more promising to determine masses or lenses of permafrost.Moreover, it was possible to correlate temperature and electrical resistivity measurements in boreholes, thus allowing the drawing of isothermal curves from electric logging in areas of continuous and discontinuous permafrost, at least when it is 'marginal'.The data for this study were obtained from the experimental station at Schefferville, Québec. [Journal Translation]
The location of the Iapetus Ocean suture in Newfoundland
Authors: McKerrow W. S. , Cocks L. R. M.
Published: April 2011

Brachiopod and trilobite faunal distributions indicate that the Iapetus Ocean was still wide enough to inhibit migration in the Middle and Late Ordovician. The presence of Silurian and Lower Devonian calc-alkaline rocks suggests that ocean crust was still being subducted long after the end of the Ordovician and that the Iapetus Ocean did not finally close in Newfoundland until the Acadian Orogeny. The Reach Fault divides successions containing different Lower Palaeozoic faunas; to the west, typical North American faunas occur in New World Island (Cobb's Arm Limestone), while to the east the rocks of the Gander region appear to have been attached to the Avalon Peninsula, with its European Lower Palaeozoic faunas, since the Early Ordovician. It is concluded that the Reach Fault marks the suture where the Iapetus Ocean closed at the end of the Early Devonian. This line probably extends across Newfoundland to the south of Buchans, and links up with the Cape Ray Fault in the southwest of the island. An Ordovician fauna from the Davidsville Group of the Gander area is illustrated for the first time; it is not clearly definitive of any faunal province.
Resistivity mapping of fossil permafrost patterns in southwestern Ontario
Authors: Greenhouse John P. , Morgan Alan V.
Published: April 2011

Fossil ice-wedge polygons, recognizable from their distinctive patterns on air photographs of certain till sheets in southwestern Ontario, can be mapped at ground level using small scale resistivity profiling. This technique is useful for locating specific polygon boundaries (for coring or trenching) which have been identified from airborne surveys.
Lead and uranium in basalts from DSDP Leg 37 cores
Authors: Cumming G. L.
Published: April 2011

Lead-isotope ratios from DSDP Leg 37 cores are linear within experimental error on a plot of 207Pb/204Pb against 206Pb/204Pb. The slope of the least-squares line corresponds to that expected for very young rocks, but the range of ratios implies a more complex multi-stage history.
Paleoecology of Eocene lacustrine varves at Horsefly, British Columbia
Authors: Wilson M. V. H.
Published: April 2011

Middle Eocene lacustrine sediments, cropping out in the valley of the Horsefly River, British Columbia, contain abundant fossils of fishes, fish scales, fish coprolites, insects, leaves, and diatoms. The fish scales, insects, and leaves are preserved in at least three sequences of alternating light tuff and dark sapropel laminae, separated stratigraphically by coarse-grained structureless sequences. The proportions of the main types of fossils occurring in the light laminae compared with the dark laminae are significantly different, and are consistent with the hypothesis that the laminations are varves, with dark organic winter laminae and light inorganic summer laminae. Occasional graded sandy layers contain carbonized allochthonous plant remains and represent turbidity deposits caused by storms in the drainage basin.It is proposed here that the varves were deposited in the deeper regions of a stratified, monomictic or meromictic lake in a warm temperate climate. The depositional environment was anaerobic, containing abundant hydrogen sulphide, and was free of turbulence and benthos. Fish were entombed mostly during the winter, insects during the spring and summer, coprolites during the summer, and deciduous leaves during the late summer and autumn. The fish died of starvation and (or) overturn-induced anoxia.
Early Cambrian algae croppers
Authors: Edhorn Anna-Stina
Published: April 2011

Conical, calcareous tubes and worm burrows in Lower Cambrian stromatolites in eastern Newfoundland are found associated with indications of grazing activity. Cropping by early herbivores may have reduced the degree of dominance of the existing stromatolite-constructing algae, allowing diversification of new groups. Stromatolites, so plentiful in Precambrian and early Cambrian time, slowly perished and at present are limited only to specific environments. The cause of this drastic reduction was probably the activity of cropping, grazing, and burrowing animals.
Structural interpretation of the Timmins Mining area, Ontario
Authors: Davies J. F.
Published: April 2011

A reappraisal of Timmins structure indicates two periods of deformation, one involving N–S compression and a second characterized by a SW–NE couple that reoriented first-period folds and formed the Porcupine Syncline. Major faulting also resulted from this couple. Structure sections reveal that ultramafic rocks and felsic schists are stratigraphically distributed, suggesting that they are volcanic rather than intrusive. Problems concerning the origin, timing, and emplacement of gold and copper mineralization are considered in the context of the present structural interpretation.
Selected element concentrations in the post-glacial sediments of Thunder Bay, Lake Superior: distribution and methods of analyses
Authors: Mothersill John S.
Published: April 2011

Aqua regia digestion is a reliable method of extracting elements present in sediments from adsorbed positions, from solution in the interstitial water, and from precipitated oxides, hydroxides, and sulphides. The aqua regia method, when used in combination with the HF–HNO3–HClO4 method for total element extraction from the sediments, provides valuable information on the relative amounts of Fe, Mn, Ni, Cu, Co, Cr, and Zn which are able to migrate in the upper part of the sedimentary sequence. The distribution of Fe and Mn are strongly controlled by pH and Eh. Ni, Cu, Ci, Cr, and Zn are controlled by adsorption to Fe hydroxides, organic matter, and MnO2 as well as Eh and pH with Cu, Co, and Zn showing a stronger correlation with MnO2 than with organic matter and Fe hydroxides.
La tectonique du front appalachien dans la région de St-Dominique, Québec
Authors: Prichonnet Gilbert , Raynal Michel
Published: April 2011

The 'St-Dominique crest' (Quebec) represents one of the best exposed thrust slices in the external domain of the Appalachians (Ordovician). The observation and analysis of the main deformations show in particular that the apparent discontinuity of the stratigraphic units cannot be explained by transversely faulted blocks, and indicate that the 'crest' is not part of a collapsed structure, as suggested by previous authors. On the contrary, the apparently discontinuous formations can be explained by a succession of 'en échelon' folding. The fracturing, which allows small internal imbricated structures, is in harmony with this moderately folded framework and is also compatible with the relative displacements of imbricated compartments on the front and on the monoclinal side of the slice. Succeeding the compression phase, a tension phase induced an additional downward movement along some fault planes.On a small scale, an interesting model of folding and imbricated structures, useful to under-stand the larger imbricated slices of the regional Appalachian frontal domain, is offered by this structure.The lack of transverse faulting along the slice and the fact that the slice is plunging at both extremities suggests that the inference of transverse faulting along the outer Appalachian front in the Quebec area needs reexamination.
Les formes de glaces des grottes de la Nahanni, Territoires du Nord-Ouest, Canada
Authors: Schroeder J.
Published: April 2011

Exploration has been continuing on the karst system developed within the cliffs of the First Canyon (300–1050 m deep) of the South Nahanni River(61°18′ N, 124°10′ W). Probably the most northerly on the North American continent, this karst region is within the discontinuous permafrost zone, at the southern limit of the tundra. The caves contain ice of the type which depends on the present subarctic climate (two-dimensional hexagonal ice crystals, ice like calcite speleothem and 'secondary' ice), or on a long-term climatic change of ± 2400 years (massive ice deposits and sponge-like ice deposits).
The geology and evolution of the Pinchi Fault Zone at Pinchi Lake, central British Columbia
Authors: Paterson I. A.
Published: April 2011

At Pinchi Lake, the Pinchi Fault Zone separates the early Mesozoic Takla Group to the east from the late Paleozoic Cache Creek Group to the west. Between these regions a complex fault system involves a series of elongate fault-bounded blocks of contrasting lithology and metamorphic grade. These blocks consist of: (a) highly deformed aragonite–dolomite limestone and blueschist, (b) pumpellyite–aragonite greenstone, (c) a harzburgite–gabbro–diabase–basalt ophiolite sequence, (d) serpentinized alpine ultramafite, and (e) Cretaceous (?) conglomerate. The blueschist probably formed at 8–12 kbar (8 × 105–12 × 105 kPa) and 225–325 °C during a penetrative early deformation which was closely followed by a later deformation associated with a Late Triassic uplift and cooling event. The ophiolite sequence is overlain by Late Triassic sediments which locally contain aragonite suggesting that at least part of the Takla Group may have also undergone high pressure – low temperature metamorphism.The evolution of the 450 km fault zone is discussed and a model is proposed which involves right lateral transform faulting on the Pinchi Fault and underthrusting along northerly dipping subduction zones during the Late Triassic. The blueschist formed at high pressures in such a subduction zone and leaked to the surface in zones of low pressure along an active transform fault.
Middle Devonian (Eifelian) conodonts of the genus Polygnathus from the Wadleigh Limestone, southeastern Alaska
Authors: Savage Norman M.
Published: April 2011

Conodonts from the lowest known horizon of the Wadleigh Limestone, southeastern Alaska, include Polygnathus trigonicus Bischoff and Ziegler, P. angustipennatus Bischoff and Ziegler, P. angusticostatus Wittekindt, P. costatus costatus Klapper, P. pseudofoliatus Wittekindt, P. kockelianus australis Jackson, and P. linguiformis linguiformis Hinde. The fauna is of late Eifelian age. Immediately below this horizon, but with the contact covered by the sea, are thick conglomerates of the Karheen Formation which are thought to be no younger than Emsian. No marine deposits of early or middle Eifelian age have yet been recognized in southeastern Alaska. The presence of thick conglomerates underlying late Eifelian limestones may be evidence of a terrestrial interval possibly resulting from an early Middle Devonian orogeny.
Two major Wisconsin lithostratigraphic units in southwest British Columbia
Authors: Armstrong J. E. , Clague J. J.
Published: April 2011

Two lithostratigraphic units, Quadra Sand and the Cowichan Head Formation, are overlain by Vashon till and associated glacial sediments and underlain by Dashwood and Semiahmoo drift deposits in coastal southwest British Columbia. Each unit is formally described and stratotypes are presented.Quadra Sand consists of cross-stratified, well-sorted sand, minor gravel, and silt deposited as outwash in front of glaciers advancing into the Georgia Depression at the beginning of the Fraser Glaciation. It is diachronous, deposition having commenced earlier than 29 000 years BP at the north end of the Georgia Depression but not until after 15 000 years BP at the south end of the Puget Lowland.The Cowichan Head Formation, deposited during the Olympia nonglacial interval, underlies Quadra Sand and consists of parallel-bedded silt, sand, and gravel, in part plant-bearing. The unit is divisible into a lower marine member and an upper fluvial and estuarine member.
Temporal changes in foraminiferal distributions in Miramichi River estuary, New Brunswick
Authors: Scott David B. , Medioli Franco S. , Schafer Charles T.
Published: April 2011

Distribution of foraminifera from surface sediments collected during September 1975 and February 1976 in Miramichi estuary are described and compared to similar data reported previously from the same estuary. Three major assemblage zones presently occupy the estuary: the river, transitional, and open bay assemblage zones. Only two assemblage zones were observed in earlier studies: river and open bay. Sedimentological and geomorphological evidence suggests that circulation patterns in the estuary have changed sufficiently in the past decade to allow the transition assemblage to replace the open bay in large parts of the estuary.A comparison is made between the distributions obtained using a cluster analysis and those obtained using a direct, intuitive approach. The two methods yield almost identical results in this study and the cluster analysis should be a valuable tool when large amounts of data must be interpreted.Seasonal observations were limited; however, no major shifts of faunal zones were detected from September to February. One species, Protelphidium orbiculare, appears to be more common in the warmer months and may require relatively warm temperatures to reproduce.A new complementary classification of estuaries based on circulation detected by foraminiferal assemblages is proposed.
The seismicity of northern Canada
Authors: Basham P. W. , Forsyth D. A. , Wetmiller R. J.
Published: April 2011

The addition of over 1000 earthquakes to the northern Canadian data file during the past 3 years provides sufficient data to delineate distinctive patterns of seismicity, although the short history of low level earthquake monitoring and the temporal and spatial clustering of earthquakes suggests that not all potentially active areas may yet have been identified. The data indicate areas of activity near the larger earthquakes located teleseismically prior to the post-1960 northern expansion of the Canadian Seismograph Network and additional clusters and trends that were not previously apparent. Correlations to seismicity with major deformational trends in the Yukon – Mackenzie Valley, the northern continental margin, the Arctic archipelago and encircling much of the Baffin Island – Foxe Basin area show that structures formed or reactivated by Palaeozoic and later orogenic phases are continuing activity in response to the contemporary stress field.Possible zones of Cenozoic movement show pockets of high seismic activity but important gaps in the trends remain off Banks Island, along Nares Strait, and in Davis Strait. Tectonic forces characteristic of plate margins do not appear to be acting in the Canadian Arctic, and contemporary movement of Greenland with respect to Baffin Island does not need to be invoked to explain the seismicity in the Baffin region.Epicentre clusters in the Beaufort Sea and offshore of Ellef Ringnes Island are distributed mainly over the seaward gradient of elliptically shaped free air anomalies, indicating seismic adjustment in basement structures to uncompensated wedges of Recent–Tertiary sediments. Seismicity around much of the Baffin Island – Foxe Basin block shows a significant correlation with the interval of isostatic equilibrium between broad areas of current postglacial uplift. If northeastern Baffin Island is a hinge zone in the rebound process, and the zone from Hudson Strait to northeastern Keewatin a line of inflection in the rate of uplift contours, the reactivation of structures is occurring along zones of high differential stress.
The ophiolites of southern Quebec: oceanic crust of Betts Cove type
Authors: Church W. R.
Published: April 2011

The Thetford and Asbestos ophiolites of the Eastern Townships of Quebec (Internal Domain) resemble the Betts Cove ophiolite of Newfoundland in three significant respects: (1) ultramafic cumulate sequences of the ophiolites include units with cumulus orthopyroxene; (2) the 'gabbro' unit is composed of a relatively thin yet compositionally and structurally complex clinopyroxenite–gabbro member which unconformably overlies the ultramafic cumulate sequence; and (3) basaltic rocks associated with the ophiolites have extremely low Ti contents. In contrast, in the Bay of Islands region of western Newfoundland (External Domain) basaltic rocks of the ophiolites of the Humber Arm Allochthon have Ti contents typical of normal oceanic crust; the cumulate sequences rarely contain cumulus orthopyroxene; and the 'gabbro' unit includes a major sequence of cumulus plagioclase-bearing rocks which appear to conformably follow the ultramafic cumulates. The Baie Verte ophiolite of Newfoundland is intermediate in character and location between the Betts Cove and Bay of Islands complexes. All of the ophiolites of the Internal Domain are overlain by sequences having conglomerate, olistostrome, and greywacke units containing abundant clastic material derived from ophiolitic rocks.The homologous nature of the Betts Cove and Thetford ophiolites lends some support to the view that the Fleur de Lys and Caldwell - Chain Lakes orthotectonic zones of the Appalachian system are laterally correlative, and that all ophiolites of the Internal Zone of the Appalachians are allochthonous rather than collapsed in situ small ocean basins. The variation exhibited by the ophiolites of the Appalachian system, even within the Internal Zone, cautions however against a too simplistic view of the role of ophiolites in plate tectonic models of orogenic belts of Appalachian type.
A radiometric age of deformed granitic rocks in north-central New Brunswick
Authors: Fyffe L. R. , Irrinki R. R. , Cormier R. F.
Published: April 2011

A Rb–Sr whole-rock isochron age of 489 ± 14 Ma based on a half-life of 5.0 × 1010 years is obtained from deformed granites in north-central New Brunswick indicating a Lower Ordovician age for these rocks. The corresponding age using a half-life of 4.88 × 1010 years is 479 ± 14 Ma. The granite is consanguineous with felsic volcanic rocks of the Tetagouche Group.
The natural remanent magnetization of sediment cores from the Beaufort Sea
Authors: Vilks G. , Hall J. M. , Piper David J. W.
Published: April 2011

Two sediment cores collected from the continental slope of the southeastern Beaufort Sea show zones of stable shallow geomagnetic inclination at close to 0° in contrast with the dipole value of 80°. Although the cores were taken 60 km apart, the shallow inclination sections are sufficiently similar in form to be useful as potential correlation horizons, on the reasonable assumption that the same geomagnetic excursion is recorded in both cores.The cores consist of silt and clay, showing fine silt–clay laminae or structureless mud on X-radiographs. Except for the surface 2.5 m of core 810, foraminifera are sparse everywhere.The 14C dates for total organic carbon place the recorded paleomagnetic event at between 10 000 and 40 000 years BP. According to paleontologic evidence, the event took place between 6 000 and 16 000 years BP. The later dating method is considered to be more reliable. Sediment cores from other high deposition rate areas need to be examined paleomagnetically to determine the areal extent of this Beaufort Sea geomagnetic excursion.
Single-domain theory for the reversible effect of small uniaxial stress upon the remanent magnetization of rock
Authors: Hodych J. P.
Published: April 2011

This paper on small uniaxial stress changing the remanent magnetization of rock is a companion to my previous paper on stress changing susceptibility, both phenomena being of current interest in attempts at earthquake forecasting.Theoretical expressions are derived (using rigorous energy-minimization but ignoring thermal activation) for reversible change in remanence parallel to the stress axis for samples containing single-domain grains of a ferromagnet with cubic magnetocrystalline anisotropy (K1 positive or negative) and anisotropic magnetostriction. The grains are assumed to be non-interacting and randomly oriented spheres or ellipsoids of revolution elongated along [Formula: see text], [Formula: see text], or [Formula: see text]. Also, approximate expressions are given for samples containing multidomain grains with very strongly pinned walls. Thermal (or chemical), anhysteretic, and saturation remanence are discussed.For remanence change perpendicular to the stress axis, one expects −1/2 the above expressions for change parallel to the stress axis, which is easily proven for thermal remanence.The expressions predict that for magnetite-bearing rock the decrease in thermal remanence along a 100 bar (1 × 104 kPa) compression axis should be 0.76% for spherical single-domain grains, 0.27% for 1.4 to 1 elongation along [Formula: see text], and 0.09% for great elongation along [Formula: see text]. The decrease for equidimensional multidomain grains with strongly-pinned walls should be ~0.38%. These are all much smaller than the corresponding estimates for susceptibility, but both remanence and susceptibility decreases should become larger and more comparable as titanium content increases.
Stratigraphic setting of the type specimen of Carpocrinus arcticus Frest and Strimple from the Late Silurian of Somerset Island, Arctic Canada
Authors: Narbonne Guy M.
Published: April 2011

The type specimen of Carpocrinus arcticus Frest and Strimple was collected approximately 65 m below the upper boundary of the Read Bay Formation (Member A) at Fury Point, Somerset Island. Associated brachiopods, trilobites, and bryozoans suggest a Ludlovian age for this specimen.
Disorientation of Paleozoic hemispherical corals and stromatoporoids
Authors: Kobluk David R. , Bottjer David J. , Risk Michael J.
Published: April 2011

The size distribution and orientation of massive hemispherical tabulate corals and hemispherical stromatoporoids from the Fossil Hill and Manitoulin Formations on Manitoulin Island (Niagaran and Alexandrian, Ontario), and of hemispherical stromatoporoids in the Flume and Upper Cairn Members of the Miette reef complex (Frasnian, Alberta) and the Jamesville Member of the Manlius Formation (Helderbergian, New York), was determined. In all five sample populations there is no statistically significant difference in the mean size between populations of heads in growth position and those disoriented. The process or processes responsible for disorienting heads evidently did not selectively disorient or remove specific size classes. Such disorientation, associated with little lateral transport of heads, could have been accomplished by infrequent short-lived strong wave and current action (storms), structural or soft substrate instability caused by increasing skeleton size due to growth or bioerosion, or some as yet unknown factor.Size-frequency distributions are potentially of value in separating in-place populations from those that have undergone disorientation or transport by size-selective processes. In a paleoenvironmental study this type of data, in conjunction with other information, such as sedimentological evidence or presence or absence of borers, could then be used to help determine the processes of disorientation and (or) transport.
A tide-influenced delta complex in the upper Proterozoic Shaler Group, Victoria Island, Canada
Authors: Young G. M. , Long D. G. F.
Published: April 2011

The Reynolds Point Formation is the second formation of the Shaler Group of Victoria Island. It has a maximum known thickness of about 1100 m. It comprises four members as follows: basal terrigenous clastics, a thick carbonate-dominated unit, a second terrigenous clastic member, and a mixed carbonate–clastic sequence. The lower clastic member is the subject of this report. Its greatest known thickness is about 215 m. The basal part consists of dark green and purple shaly mudstones interpreted as prodelta and distal delta slope deposits. These fine grained sediments were spread out westward across an extensive, strongly current-influenced shelf sea that contained abundant stromatolites. These stromatolites comprise the orange-weathering stromatolitic biostrome of the topmost unit of the underlying Glenelg Formation. The abrupt contact between the two formations and the strongly contrasted nature of the rock types involved suggest that the platform underwent rapid subsidence. Sandstones, siltstones, and minor mudstones of the overlying (main) part of the lower clastic member are interpreted as platform deposits of a prograding marine delta complex. These include deposits of tidal channels and associated tidal flats, commonly forming fining-upward sequences, beach deposits, and mudstones and siltstones that may be lagoonal or interdistributary bay deposits. These fine grained rocks contain casts of salt crystals. Subsidence of the delta platform is recorded by the overlying suite of deeper water grey shales and shaly carbonates that constitute the lower part of the carbonate member of the Reynolds Point Formation. Gradual filling and shallowing is indicated by upward transition from shaly beds to a thick, current-influenced stromatolitic biostrome. This pattern of pulsatory subsidence, followed by gradual sedimentary filling is shown by both the basal clastic member and the overlying beds.
Lateral variations in upper crustal structure below the La Malbaie area from slowness, azimuth, and traveltime measurements of telleseisms
Authors: Hearty D. J. , Mereu R. F. , Wright C.
Published: April 2011

A temporary seismic network located in the La Malbaie region of eastern Quebec during the summer of 1974 for studying the local seismicity of the area was used as a seismic array to measure directly the slowness and azimuth of the P arrivals from 18 teleseismic events. A consistent bias in the arrival vectors was observed for rays approaching the array from the south (i.e. azimuths 181°–227°). This bias can be explained by a thickening of sedimentary strata beneath the south shore of the St. Lawrence River as opposed to the outcropping Precambrian basement rock on the north shore. The sedimentary accumulation can be interpreted in terms of a sloping interface located under the network between sediments and Precambrian rock or a thick horizontal sedimentary layer underlying the south shore of the St. Lawrence River.