bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertical Packing of Flat Stones
Authors: Dionne Jean-Claude
Published: April 2011

Pavements of flat stones vertically packed on edge occur on platforms cut in slates and shales along the shores of the St. Lawrence Estuary and Lake Saint-Jean (Québec). Large surfaces of the rock platforms are covered with flat stones, which stand nearly vertically and are tightly packed and interlocked. Stones are irregularly arranged or radially and concentrically grouped around several centers or boulders. This unusual disposition and arrangement of flat stones is caused by wave action rather than by periglacial processes as suggested earlier.
A Pteraspidid in the Dalhousie Formation (L. Devonian) at Dalhousie, New Brunswick
Authors: Dineley D. L.
Published: April 2011

A small pteraspidid is the first vertebrate to be identified from the Lower Devonian Dalhousie Formation at Dalhousie, N.B. It supports a correlation of this formation with a red bed sequence in the eastern Cobequid Mountains and the Knoydart Formation in Nova Scotia, and is older than the Atholville Beds near Campbellton, N.B.
Paragenesis and Isotopic Composition of some Gangue Minerals from the Uranium Deposits of Eldorado, Saskatchewan
Authors: Sassano G. P. , Fritz P. , Morton R. D.
Published: April 2011

A paragenetic sequence of the common mineral constituents of the uraniferous vein deposits of the Fay Mine and Bolger open pit of Eldorado Nuclear Ltd., in northwestern Saskatchewan, is presented.Pitchblende associated with hematite, pyrite, chalcopyrite, bornite, galena, and clausthalite in quartz ± calcite ± dolomite gangues is found in veins cutting folded Tazin metamorphics, adjacent to the St. Louis Fault. Fluid inclusion studies reveal a cooling sequence from the initial phase of mineralization at 440 ± 30 °C down to the final stages at around 80 ± 10 °C. Stable isotope studies, augmented by petrographic data, serve to distinguish at least five generations of carbonate in the ore veins. Early generations of dolomite have apparently not undergone any significant recrystallization or isotopic readjustment and exhibit original restricted δ18O (SMOW) values of 9.5 to 11.0‰ and δ13C (PDB) values of −0.60 to 0.55‰. Isotopic evolution via equilibration with wall rocks has resulted in the deposition of late-stage calcites characterized by δ18O (SMOW) values of + 13.2 to + 14.5% and δ13C (PDB) values of −15.9 to −16.8‰. The strong decrease in δ13C may possibly be explained by a decrease in the amount of CH4 present in the system. It is felt that the deposits were generated by metamorphic hydrothermal fluids with initial δ18O (SMOW) values of + 6 to + 8‰, which during cooling underwent isotopic exchange with the host metamorphic rocks and became depleted in 18O. The final stages of mineralization were possibly effected by some influx of isotopically lighter surface waters into an otherwise essentially 'closed' system. Present day waters from the Fay Mine have δ18O (SMOW) values of −16.0 to −16.2‰ and could represent products of a continuing evolution of the hydrothermal fluids.
The Geology and Geochronology of the Echo Bay Area, Northwest Territories, Canada
Authors: Robinson B. W. , Morton R. D.
Published: April 2011

In the Echo Bay region of Great Bear Lake the Echo Bay Group has been intruded by Precambrian granites, granodiorites, aplites, and diabases. This group, which has undergone zeolite-facies regional metamorphism, has a lower dominantly sedimentary-pyroclastic sequence (about 1320 m thick) and an upper volcanic sequence (> 1500 m thick). The Lower Echo Bay sub-Group consists of tuffs and cherts with a 190 m thick intermediate lava flow and occasional thin limestones. A sequence of andesites and pyroclastics comprises the Upper Echo Bay sub-Group. Contact metamorphism of the hornblende hornfels and albite–epidote hornfels facies has been induced by the granitic intrusions. A Rb–Sr isochron for the Upper Echo Bay sub-group volcanics gives an age of 1770 ± 30 m.y. K–Ar apparent ages for the granite, granodiorite, and volcanics average around 1650 m.y., possibly reflecting local argon loss up to this date. Mineralized veins with a pitchblende-Co,Ni arsenide-silver-Fe, Cu, Ag, Bi, Zn. Pb sulfide para genesis are mainly confined to the sedimentary-pyroclastic horizons of the Lower Echo Bay sub-Group. It is possible that the mineralization was effected by fluids generated during the low-grade regional metamorphism and that some contribution was made to ore genesis by the thermal regime developed during the diabase intrusion.
Oxygen Isotope Studies of Fresh and Weathered Submarine Basalts
Authors: Muehlenbachs Karlis , Clayton Robert N.
Published: April 2011

The 18O/16O ratios of fresh unmetamorphosed basalts from the Reykjanes, Mid-Atlantic, and Gorda Ridges and the East Pacific Rise fall in a narrow range of 5.5–5.9‰ (SMOW), identical to those of basalts from oceanic islands. Large plagioclase xenocrysts in some of the basalts are not in isotopic equilibrium with coexisting olivine. The basalts react with sea water at the ambient sea-floor temperature to form clays, resulting in an increase in δ18O of the basalt of 0.25‰ per m.y. This provides a very sensitive method to detect early stages of weathering, which otherwise might go unnoticed. Advanced submarine weathering of basalt can remove nearly one half of its SiO2, MgO, CaO, and Na2O and lesser amounts of Al2Os and TiO2. Weathering does not proceed deeply enough into the basaltic sea floor to affect the chemical composition of sea water. Since it is likely that large amounts of basaltic debris (less than a few cm in radius) are on the ocean floor, their weathering can affect the ocean-sediment budget of TiO2, Al2O3, SiO2, MgO, and CaO.
The Gander Lake and Davidsville Groups of Northeastern Newfoundland: New Data and Geotectonic Implications
Authors: Kennedy M. J. , McGonigal M. H.
Published: April 2011

Structural studies of rocks in the Gander region of Newfoundland and on the coast to the north have indicated that rocks that were previously assigned to the Middle Ordovician Gander Lake Group actually consist of a composite sequence that contains pre-Middle Ordovician polyphase deformed metasedimentary rocks and even older gneissic rocks as well as Middle Ordovician sediments and mafic volcanics. The possible implications of these results are discussed and map units in the region are redefined.
Late Wisconsinan Ice-Wedge Polygons near Kitchener, Ontario, Canada
Authors: Morgan Alan V.
Published: April 2011

Reconnaissance from a light aircraft has revealed areas of polygonal ground east of Kitchener, Ontario. Examination of aerial photographs of the same region has shown additional polygons all developed upon Port Stanley II Till. Trenching of a polygon has exposed wedge-shaped sand and gravel infilled structures interpreted as ice-wedge casts. The wedges are believed to have been active prior to 13 000 years B.P., probably under tundra conditions, with mean annual air temperatures some 25 °F (13–14 °C) cooler than present.
Textural Variation in Sub-Environments of the Shallow-Water Wave Zone, Kouchibouguac Bay, New Brunswick
Authors: Greenwood Brian , Davidson-Arnott Robin G. D.
Published: April 2011

Textural analysis of sands from the morphodynamic environments of a tidal, shallow-water, wave environment in Kouchibouguac Bay, New Brunswick, reveals sediment populations that are statistically unique to each zone under low wave energy conditions. Measures of average size (ϕ mean), sorting (ϕ standard deviation and relative entropy), and skewness of sediment size distributions vary according to location in four sub-environments (offshore bar, trough, breaker zone, and swash zone). Phi kurtosis is shown not to be environmentally sensitive in this area. Multivariate analysis using Mahalanobis D2 and multiple linear discriminant functions allows differentiation of the sediment populations. Classification into environmental groupings is good with misclassifcation being not greater than 22% (range 6.1–22%). The relative importance of individual size-frequency statistics in the discrimination of adjacent environments is interpreted in terms of the effects of changing morphology and wave-current conditions on the selective transport of sediments.
Paleomagnetism of the Et-Then Group and Mackenzie Diabase in the Great Slave Lake Area
Authors: Irving E. , Park J. K. , McGlynn J. C.
Published: April 2011

Studies of baked contact rocks and material at distances up to several kilometers from contacts show that the Mackenzie diabase acquired its remanent magnetization at the time it originally cooled about 1250 m.y. ago. Baked rocks have coercivities that are generally over twice as high as those of the diabase itself showing that they are suitable for paleomagnettc determinations. Combination of this new data (10 sites) with previous data from the Mackenzie Igneous Episode (Muskox Intrusion, Coppermine lavas, Mackenzie diabase) gives a mean pole position of 01 °N, 171 °W, Red beds of the Et-Then Group are shown to have acquired their magnetization prior to the intrusion of the diabase and probably at the time or soon after they were deposited. They have a mean direction of 294, −21 (k = 17, α95 = 10°) and a pole at 01 °S, 048 °W (K = 26, A95 = 8°). The result is based on 14 sites (10 normal 4 reversed).
Magnetism of Dikes of the Frontenac Axis
Authors: Park J. K. , Irving E.
Published: April 2011

Paleomagnetic results from 11 dikes of three different directional trends (north, northwest, and northeast) from the Frontenac axis are reported. Six northwest trending dikes (minimum age 800 m.y.) give well-grouped stable magnetization directions with a corresponding pole at 12 °S, 162 °E (N = 6, K = 85, A95 = 7°).
K-Ar Dating of the 'Cork' (Burwash Creek) Cu-Mo Prospect, Burwash Landing Area, Yukon Territory
Authors: Christopher P. A. , White W. H. , Harakal J. E.
Published: April 2011

A 26 ± 0.3 m.y. mean age was determined for quartz latite porphyry near Burwash Creek, Yukon Territory. This apparent age for mineralized porphyry represents the youngest documented porphyry prospect in the Canadian Cordillera. Cretaceous ages determined for Kluane Range intrusions agree with geologic evidence, and early Tertiary ages from the Ruby Range batholith agree with a previous radiometric determination.
Variations in Quality and Quantity of Slims River Water, Yukon Territory
Authors: Bryan M. Leonard
Published: April 2011

The Slims River, one of the two outlets draining the Kaskawulsh Glacier of the Icefield Ranges, Yukon Territory, Canada, is seen to have a variation in both quality and quantity of discharge. These variations, studied for several 24 hour periods during the summer of 1970, are reflections of both the diurnal ablation pattern of the Kaskawulsh Glacier and of a shift in the glacial drainage, a shift which is thought to be due to ice movements at the glacial terminus. Water quality and quantity was measured at the bridge where the Alaska Highway crosses the Slims River and its delta in Kluane Lake. In addition, several similar measurements were taken on tributary streams entering the Slims River below the glacier terminus. Both sets of measurements show a distinct change during early August, the water quantity decreased by a factor of 3–5 and the quality became decidedly less fresh. The change in quality is considered to be a result of the decrease in the proportion of glacial melt water in the Slims River. The effects these changes in river water may have on sediment regimes in Kluane Lake are briefly discussed.
Burial Metamorphism of Late Precambrian Sediments near St. John's, Newfoundland
Authors: Papezik V. S.
Published: April 2011

The lowest member of the Late Precambrian Signal Hill Formation (a massive, gray, lithic sandstone), exposed at the eastern extremity of the Avalon Peninsula near St. John's, Newfoundland, is cut by a system of thin veins containing quartz, calcite, and whitish prehnite. The veins, confined to a narrow stratigraphic horizon, have been found, so far, along a strike distance of 4 km. Prehnite also forms small diffuse patches in the rock, producing a distinctive mottling effect; it is associated with authigenic quartz, sericite, chlorite, and small amounts of possibly metasomatic calcite.The prehnite-bearing mineral assemblage is consistent with mineral characteristics of the prehnite–pumpellyite facies, usually considered to be the result of burial metamorphism. The patchy interstitial prehnite is believed to have been formed by a reaction between authigenic laumontite and calcite. The prehnite-bearing assemblage may have been formed under a lithostatic load not greatly exceeding the present maximum thickness of the overlying part of the Cabot Group – about 4.5 km. The formation of both the interstitial prehnite and the prehnite-bearing veins was contemporaneous with the tectonic stresses responsible for the open folding of the Cabot Group.
Zeolite Facies Metamorphism in the Silurian–Devonian Fold Belt of Northeastern New Brunswick
Authors: Mobsman David J. , Bachinski Donald J.
Published: April 2011

Zeolite facies assemblages are identified in a coastal section of Devonian rocks on Chaleur Bay, northeastern New Brunswick. This is apparently the first report of the occurrence of this facies in Paleozoic rocks of the Appalachian belt. Analcime and quartz are abundant in the basal palagonite tuff of the Lower Devonian Dalhousie Group in the type section east of Dalhousie and in similar rock at stratigraphically equivalent localities throughout the Silurian–Devonian fold belt.
Mylonitic Rocks and Flattened Garnets in the Southern Okanagam of British Columbia
Authors: Ross John V.
Published: April 2011

A zone of fine-grained laminated mylonitic rocks is described that is related to the formation of a tectonic slide produced during the refolding of an earlier fold. These mylonitic rocks are characterized by the presence of mesoscopic isoclinal folds whose axial surfaces are parallel with the overall orientation of the lamination and are genetically related to the early folds. Originally equidimensional garnets are tectonically flattened in the axial planes of these early folds as a result of the later folding and it is suggested that the mylonitic lamination is produced directly by flattening perpendicular to the lamination resulting in extensionsal flow parallel with the zone of mylonitic rocks.Thin sections of the laminated mylonitic rocks show the presence of strained augen and ribbon quartz separated by zones of small strain-free polygonal grains which have originated by syntectonic recrystallization. The two former structures have a geometric relation with the early isoclinal structures, whereas the polygonal grains are related to late orthorhombic mesoscopic folds found only within the mylonitic rocks. This latter fabric is interpreted as resulting from restricted extensional flow within the mylonitic zone. The geometry of the fabric is the same within and without the mylonitic zone, the only variation being the intense development of very small strain-free polygonal grains, which from experimental evidence require a high strain rate for their formation. Hence, these mylonitic rocks are interpreted as a zone of high strain rate produced by flattening perpendicular to their plane of flow but otherwise they have a deformational history similar to that of the enveloping rocks.
The Entoptychine Geomyid Lignimus (Mammalia: Rodentia) from Kansas and Nebraska
Authors: Storer John E.
Published: April 2011

The entoptychine geomyid Lignimus hibbardi, sp. nov., is described from the WaKeeney local fauna, and the generic diagnosis is changed to include taxa with dentine tracts on cheek teeth, and with the X-pattern of lower molars not emphasized by a V-shaped ridge as in the type species, L. montis. Occlusal patterns of lower premolars and molars of Lignimus resemble those of entoptychines, and differ markedly from those of geomyines; hence the subfamilial reference. Lignimus cf. L. montis occurs in the Norden Bridge local fauna, and Lignimus sp. in the Norden Bridge local fauna and the Crookston Bridge and Burge Members of the Valentine Formation.
Sediment Discharge from Canadian Basins into Lake Ontario
Authors: Ongley Edwin D.
Published: April 2011

Regional patterns of sediment yield from Canadian watersheds tributary to Lake Ontario are obtained by manipulating suspended and dissolved sediment and flow data originally obtained by government agencies for other purposes.
Regional Magnetic Anomalies of the Canadian Arctic
Authors: Riddihough R. P. , Haines G. V. , Hannaford W.
Published: April 2011

A contoured residual map of the vertical magnetic field, observed at an altitude of 3.5 km above sea level, provides a broad view of major tectonic patterns and relations between the Canadian Shield, the Innuitian Region, and the oceanic ridges of the Arctic Basin.
Upper Proterozoic 'Limestone Unit', Northern Dogtooth Mountains, British Columbia
Authors: Poulton T. P.
Published: April 2011

The Upper Proterozoic 'Limestone Unit' of the Horsethief Creek Group in the northern Dogtooth Mountains consists of deformed sedimentary and metasedimentary rocks with complex depositional and erosional relationships. They are interpreted to represent a westwardly prograding terrigenous and carbonate wedge in a continental margin situation. Shoaling resulted in differential carbonate deposition on top of a largely pelitic succession. Sea level fluctuations produced a complex unit characterized by alternating erosion and sedimentation, in different fades from east to west. This was succeeded by terrigenous clastic sediments with easterly or southeasterly provenance. The last recognizable events produced a widespread carbonate and sandstone blanket.A carbonate unit of similar stratigraphic position occurs in several locations north–northwest of the Dogtooth Mountains, approximately along a line paralleling the trend of Phanerozoic fades belts.
Kimberlite from Somerset Island, District of Franklin, N.W.T.
Authors: Mitchell Roger H. , Fritz Peter
Published: April 2011

A new occurrence of kimberlite located on Somerset Island in the Canadian Arctic is described. The intrusion is in the form of a diatreme showing evidence of fluidization and is emplaced in Ordovician sediments. Kimberlitic breccia containing rounded xenoliths of country rock and massive kimberlite are the dominant rock types. The massive kimberlite contains phenocrysts of olivine (Fo90–Fo93), chrome-pyrope (7–12 mol.% uvarovite), and phlogopite together with xenocrysts of pyrope-almandine (28–36 mol.% pyrope, 58–64 mol.% almandine) set in a groundmass of olivine (Fo89.5), magnetite, perovskite, and serpentine. Abundant dolomitic carbonate, which replaces the silicate groundmass, is considered to be primary and to represent a late stage immiscible phase. Emplacement of the diatreme is thought to have been controlled by a crustal lineament defined by the Boothia Uplift. An Upper Ordovician or Lower Silurian age is postulated on the basis of the lack of country rock xenoliths older than Upper Ordovician age within the diatreme.
Detrital Garnet and Muscovite in Late Precambrian Sandstone near St. John's, Newfoundland, and their Significance
Authors: Papezik V. S.
Published: April 2011

The lower member of the Signal Hill Formation of Late Precambrian age, a lithofeldspathic sandstone exposed near St. John's, Newfoundland, contains small but persistent amounts of garnet and muscovite. These minerals are not known to occur in rocks of the Harbour Main Group and the Holyrood granitic pluton of the Avalon Peninsula, previously considered to be the source of the Signal Hill sediments. As paleocurrent studies indicate a northeasterly provenance of the sediment it is suggested that the rock may have been derived from Precambrian gneissic and granitic basement, now covered by the ocean, similar to the Precambrian(?) basement rocks along the western flank of the Avalon Platform.
Evolution of the Labrador Sea
Authors: Hyndman R. D.
Published: April 2011

The age and spreading rate of the Labrador Sea have been computed from the basement bathymetry. The data give a time of termination of opening 48 m.y. ago and a mean spreading rate of 0.64 cm per year, in good agreement with previous estimates from magnetic data. The shallow depths in the Labrador Sea must be accounted for by assuming that the present Iceland hot spot or mantle plume was located under Davis Strait, to the west of Greenland during the opening. A model is proposed for the separation of Greenland from Europe and Canada driven by this plume.
Palynology of the Great Lakes: The Surface Sediments of Lake Ontario
Authors: McAndrews John H. , Power Dennis M.
Published: April 2011

Pollen was analyzed in the surface 1 cm of sediment taken from 90 sample stations collected in 1968 from a 16 km grid on Lake Ontario. Sixty-nine taxa were identified and the more abundant taxa subjected to trend surface analysis. Pollen concentration in 60 samples; ranged up to 240 000 grains per g dry sediment with the higher concentration in the offshore silt and clay sediments of the basins. Pollen percentages of 80 stations were based on 100 or more tree pollen with the average percentage values above 5% for tree pollen being Pinus 33.8, Quercus 23.6, Betula 8.3, Cupressineae 6.3, and Acer saccharum 5.5.The highest values of herb pollen were of weedy taxa, and these are Ambrosia 46.1, Gramineae 20.0, and Chenopodiineae 5.8. Throughout the greater part of the lake the percentages were generally uniform and reflect the vegetation of the drainage basin of the lake. Local variations are related to recycling of pollen from older sediments and to local river sources. Comparison of pollen percentages of Lake Ontario with percentages in the surface sediment of nearby small lakes shows that Lake Ontario has a generalized assemblage derived from a broad source region but that Tsuga, Ulmus, and Fagus are relatively under-represented for poorly understood reasons. The general uniformity of percentages in Lake Ontario suggests that pollen diagrams can be widely correlated within the lake.
Mode of Aggregation of Hoegisphaera (Chitinozoa)
Authors: Legault J. A.
Published: April 2011

Specimens of Hoegisphaera, recovered from the Rockport Quarry Member of the Hamilton Formation (middle Devonian) of southwestern Ontario, demonstrate a mode of aggregation previously undescribed for Chitinozoa. It differs from the previously reported chain or cluster habits in being a mat-like aggregate of discrete vesicles held together by a delicate membrane. This new observation has taxonomic and phylogenetic significance.
Variation in the Composition of Plagioclase and Epidote in some Metamorphic Rocks near Bancroft, Ontario
Authors: Rambaldi Ermanno R.
Published: April 2011

A Precambrian metamorphic terrain near Bancroft displays a variation in metamorphic grade, as indicated by the presence of the following metamorphic zones: garnet, staurolite–biotite, kyanite–biotite, sillimanite, and sillimanite–garnet–biotite.In rocks that contain plagioclase and epidote, there is a general increase in the anorthite content of plagioclase and a decrease in the Al content of epidote with increasing metamorphic grade. Plagioclase crystals are commonly zoned, becoming richer in anorthite toward the rims, and epidote crystals may also be zoned, becoming enriched in iron toward the rims. Various chemical reactions are proposed to account for these changes.In rocks that do not contain epidote, plagioclase is typically albitic in composition, regardless of metamorphic grade.In rocks containing microcline, some albite has evidently exsolved from the microcline, resulting in the development of sodic rims about plagioclase crystals and normal zoning in these crystals.The distribution of albite between plagioclase and microcline is in agreement with the results from other metamorphic terrains of similar grade. Observed irregularities in this distribution may be attributed to exsolution of albite from microcline.Mineralogical and chemical data from the study area provide an opportunity to propose various chemical reactions, some of which may closely approach those that have taken place within the rocks.
A Gravity Model for the Guichon Creek Batholith, South-central British Columbia
Authors: Ager C. A. , Ulrych T. J. , McMillan W. J.
Published: April 2011

The Guichon Creek batholith, located in south-central British Columbia, contains several large, low-grade copper deposits of considerable economic importance.A three dimensional model for the batholith has been proposed on the basis of a gravity survey conducted in 1971. Its gross shape can be likened to that of a flattened funnel-like structure with a tilted spout. The distribution of mineral deposits appears to be spatially related to the surface projection of the core of the batholith.
Geological Implications of Valley Rebound
Authors: Matheson D. S. , Thomson S.
Published: April 2011

An air photo survey along some rivers in Central Alberta revealed the frequent occurrence of a raised valley rim in the ground surface adjacent to valleys where postglacial channels were incised through a region of low topographic relief. Subsequent more detailed studies lead to the conclusion that, in large part, these features are due to elastic rebound of the rock into which the valley has been eroded. Rebound of the valley floor occurs due to vertical stress relief and gives rise to a gentle anticlinal structure. This structure and the upwarping of the beds in the valley walls can be predicted by a mathematical model based on elastic behavior and incorporating modifications to deal with stratified rock masses.Evidence of valley rebound was noted at the sites investigated and typical cases are presented. The amount of rebound varies with the modulus of elasticity of the rock and may be as much as 10% of the valley depth.The upwarping of the beds will locally influence the dip of the beds. The rebound should be accompanied by interbed slip which would give rise to gouge zones. If these gouge zones occur near the base of the valley walls, they will have an important bearing on landslide activity. The raised valley rim has other geomorphological implications.
Medusoid Impressions in the Lower Paleozoic Rocks of Eastern Newfoundland
Authors: Nautiyal Avinash Ch.
Published: April 2011

Two medusoid impressions of discoidal form with radial ridges and striations were collected from the Lower Paleozoic rocks (Bell Island Group) of Kelly s and Bell Islands in the southeastern part of the Conception Bay area.
Paleomagnetism of Metamorphic Rocks of Daly Bay and Melville Peninsula, Churchill Structural Province
Authors: Park J. K.
Published: April 2011

Studies of metamorphic rocks from the Daly Bay and Melville Peninsula areas of the Churchill Structural Province of the Canadian Shield have yielded two groups of directions. Group A directions (16 sites) from gneisses of basic and intermediate composition have the mean 196°, +55 °(N = 16, k = 39, α95 = 6.1°) with a corresponding pole at 12°N, 101°W (k = 27, α95 = 7°). These rocks are foliated and the average effect of anisotropy on the high coercive force (stable) components is small. Evidence is presented to show that agewise the pole falls within the range of 1250 to 2100 m.y. The pole lies on the apparent polar wander curve for the Canadian Shield in the time range 1425 to 1725 m.y. which defines its age within narrower limits. Since the mean K–Ar age is 1622 ± 30 m.y., the magnetization of Group A may reflect this age. This result shows that metamorphic rocks can be used to provide useful paleomagnetic data. The Group B magnetization, however, derived mainly from acidic gneisses and having a mean direction of 055°, +72 °(N = 8, k = 18, α95 = 13°) and a pole at 67°N, 009°W very close to the present pole, is probably of recent origin.
A Transfer Function Analysis of a Geomagnetic Depth Sounding-Profile across Central British Columbia
Authors: Dragert H.
Published: April 2011

Time variations of the geomagnetic field observed across British Columbia at a mean latitude of 54 °N are analyzed using 'single-station' and 'paired-station' optimum transfer functions. The frequency and spatial dependence of both coastal and inland geomagnetic anomalies are estimated with the following results. (1) The normal coast effect is strongly perturbed by lateral conductivity inhomogeneities both north and south of the profile. (2) A simple, single NW–SE striking conductivity contrast between the Cordillera and plains cannot account for the total geomagnetic anomaly in the area of the Rocky Mountain Trench; a three-dimensional model is required, incorporating (i) a lateral inhomogeneity striking east–west and located to the south of the profile, (ii) the effect of induction by the vertical component of source or secondary fields.
Paleomagnetism of some Grenville Province Rocks
Authors: Palmer H. C. , Carmichael C. M.
Published: April 2011

Anorthositic rocks 20 to 30 km south of the Grenville Front in the Grenville Province of Ontario have a stable remanent magnetization which yields a paleomagnetic pole at 161 °E, 8 °N. This pole is close to other poles from the Precambrian of North America of 1050 m.y. age. Paleomagnetic results have also been obtained from two rock units in the southern part of the Grenville Province of Ontario. These are a pyroxenite exposed near Wilberforce and the Tudor Gabbro exposed near Madoc. The directions of remanent magnetization yield pole positions as follows: Wilberforce pyroxenite—148 °E, 14.5 °S; Tudor Gabbro—137 °E, 17 °N. These pole positions, together with others from the literature, which have been derived from rock units 200 km or more south of the Grenville Front, plot farther west in the Pacific than do poles of inferred similar age from other regions of North America. A possible interpretation of these results is that the southern part of the Grenville province was formed some 30° SE of its present position.
Cirque Analysis as a Method of Predicting the Extent of a Pleistocene Ice Advance
Authors: McLaren Patrick , Hills L. V.
Published: April 2011

Thirteen quantitative and two qualitative variables were measured for 53 cirques and their respective valleys in the Front and Main Ranges of the southern part of Banff National Park, Alberta. Each cirque and valley showed good evidence for a Late Wisconsin advance that never extended into major trunk valleys.The question being asked was: Can the maximum extent of this relatively minor advance be predicted by measuring the physical parameters of the cirque? The following equation can predict the maximum ice extent with a standard error of ±808 ft (±246.4 m): Y = 1012.8801X6 + 0.8552X3 + 2.6836X1 − 7763.6370, where Y is the maximum ice extent in ft; X6, X3, and X1 are the area (ft2), elevation (in ft), and the east–west location of the cirque respectively. However, only 64.48% of the variance of the ice extent is explained by this equation.It is suggested that the 35.52% unexplained variance is due to climatic variables, particularly those on the meso-scale, in the cirque at the time of the advance. It is possible these variables may be reflected in the degree of frost shattering of the joint and fracturing systems on the cirque headwall.It appears unlikely that a similar method could be applied to more extensive advances or glaciations because of the difficulty in obtaining precise data. However, as a method of examining a landform, similar studies will undoubtedly be extremely useful.
Structural Characteristics of some Sedimentary Basins in Northern Baffin Bay
Authors: Keen C. E. , Barrett D. L.
Published: April 2011

Geophysical measurements along tracks crossing some of the main structural features of the northern Baffin Bay shelf are described. The data consist of seismic reflection, seismic refraction, gravity, and magnetic measurements. Results in four areas—Lancaster Sound, Melville Bay, Smith Sound and Jones Sound—are presented. Magnetic and gravity data are used to define the extent of sedimentary basins in these areas. Seismic reflection measurements delineate the structural characteristics of the upper 2 km of the sedimentary strata and allow comparisons between them to be made. Seismic refraction measurements show that the upper 2 km of sediment exhibit low velocities—less than 3.2 km/s. Little deformation of the sediments is observed in any of these areas, however, the strata in Lancaster Sound and in the Melville Bay graben appear to have experienced less faulting than those in Jones Sound and Smith Sound. Normal faults are characteristic of the latter two areas. Jones Sound is a structurally complex area and is filled by a lesser thickness of sediments than is found in the other basins. These sediments are terminated near the entrance to the sound by Precambrian basement. A deeper sedimentary basin occupies Smith Sound and trends across the Nares Strait lineament. Although the data are insufficient to allow a detailed structural analysis of the strata in these regions, we speculate that the differences in sedimentary structures can be related to the formation of the Baffin Bay ocean basin.
Nadiastrophia from the Headless Formation (Eifelian), Mackenzie Mountains, District of Mackenzie, Northwest Territories
Authors: Lenz A. C.
Published: April 2011

The genus Nadiastrophia previously recorded only from Australia and China, is described from the Headless Formation of the Mackenzie Mountains. This discovery further emphasizes the early Middle Devonian faunal affinities between the Cordilleran and southeastern Pacific regions. The Mackenzie Mountains Nadiastrophia is assigned to a new species, N. mackenziensis.
The Assemblage Quartz–K Feldspar–Biotite–Garnet–Sillimanite as an Indicator of –T Conditions
Authors: Froese E.
Published: April 2011

The assemblage quartz–K feldspar–biotite–garnet–sillimanite is common in high-grade pelitic rocks. Diverse compositions of biotite and garnet from this assemblage reflect differences in Ptotal, [Formula: see text], and T. For rocks from a small area, Ptotal probably was nearly constant. In order to show the separate effects of [Formula: see text] and of T on mineral composition, a plot of conditions indicated by various rocks with this mineral assemblage on a [Formula: see text]–T diagram is presented. This is accomplished by treating the minerals and the fluid phase as ideal solutions, by assigning reasonable [Formula: see text]–T values to one rock, and by assuming entropies for two dehydration reactions. Rocks from the Thor-Odin gneiss dome in British Columbia reflect a temperature range of about 200 °C and relatively low water pressures.
Long and Short Term Changes in the Barrier Islands of Kouchibouguac Bay, Southern Gulf of St. Lawrence
Authors: Bryant E. A. , McCann S. B.
Published: April 2011

The Kouchibouguac Bay barrier island – sand spit system is the simplest of the four large systems in the southern part of the Gulf of St. Lawrence, and occupies a relatively low wave energy environment. Present field evidence and information from a series of maps published since 1807 and a series of air photographs taken since 1930 indicate that the barriers have undergone considerable changes over the last 160 years. The changes involve shoreward retreat and repeated breaching and infilling of a series of temporary inlets. The three main inlets in the system have remained relatively constant in overall position during this period, but there have been marked local variations in the associated channels and shoals. In general terms the Kouchibouguac barriers may be considered as representative of other systems in the southern part of the Gulf of St. Lawrence and present strong similarities to the well documented barriers of the eastern coast of the United States.
Iceberg Furrow Marks on the Continental Shelf Northeast of Belle Isle, Newfoundland
Authors: Harris Ian McK. , Jollymore Paul G.
Published: April 2011

Side-scan sonar imagery indicates the presence of numerous large-scale furrows on the continental shelf northeast of Belle Isle, Newfoundland. The furrows are attributed to the ploughing action of bottom-dragging icebergs. They are typically linear troughs bordered by raised shoulders with an average width of about 30 m, a maximum observed depth of 6.5 m, and a maximum length of at least 3 km. Considered collectively, the furrows have a pronounced north-south trend, which probably reflects the general southerly drift of icebergs in the Labrador Current.
Geological Relationships Between Massive Sulfide Bodies and Ophiolitic Volcanic Rocks near York Harbour, Newfoundland
Authors: Duke N. A. , Hutchinson R. W.
Published: April 2011

Small lenses of massive copper- and zinc-rich sulfide occur in ophiolitic volcanic rocks capping the Bay of Islands Igneous Complex near York Harbour, Newfoundland. Ore was discovered in 1897 and about 50 000 tons were produced between 1898 and 1912. Recent exploratory work has outlined several ore bodies totaling 282 000 tons that contain 1.92% Cu and 4.67% Zn, assuming 20% dilution.The deposits are stratabound, occurring along an intensely altered zone that separates two members of the layered pillow lava succession. Two types of mineralization are present. Lenticular massive bodies ranging in size up to 37 000 tons are composed of brecciated pyrite, sphalerite and chalcopyrite. These are stratigraphically underlain by chalcopyrite-rich stringer mineralization in altered lava.Microscopic and petrochemical investigations indicate that the host lavas have undergone pervasive spilitic alteration and intensive propylitic alteration near ore. Geochemical studies of Co:Ni ratios in pyrite show that Ni content is highest in disseminated pyrite from the propylitized lavas and Co is highest in pyrite from stringer ore. The Co:Ni ratio for all analysed pyrite is greater than unity, suggesting a magmatic-volcanic derivation for the deposits.The geological evidence suggests that the sulfides are volcanogenic and were formed from hydrothermal fluids rich in Fe, Zn, Cu and S. These moved upward along zones of primary brecciation in the lavas, leached Fe, Ni, and Ti from the ferromagnesian minerals and deposited the massive lenses by chemical sedimentation or precipitation from the metal-rich exhalations on or near the sea floor.Comparison of the York Harbour deposits to the recent heavy metal bearing sediments of the Red Sea 'deeps', and to the Cretaceous lavas and orebodies of Cyprus, supports the above genetic interpretation, and indicates that these ores are clearly an integral part of ophiolite complexes. The comparison provides new information about sulfide mineral paragenesis during initial sedimentation, diagenesis, burial, and later metamorphism.
Unconformities on the Scotian Shelf
Authors: King Lewis H. , MacLean Brian , Fader Gordon B.
Published: April 2011

Four erosional unconformities have been recognized within the Mesozoic-Cenozoic succession on the Scotian Shelf, on the basis of data from high resolution seismic reflection profiles. Older unconformities are known from well data and others may be revealed by detailed biostratigraphic studies.The oldest of the four unconformities discussed in this paper is of Early Cretaceous age and appears to mark, with discordance, the boundary between Jurassic and Cretaceous strata on the western part of the shelf. A second angular unconformity, of Late Cretaceous age, has been recognized on the central part of the shelf where the basal part of the Banquereau Formation (Tertiary and uppermost Cretaceous) oversteps the zero-edge of the Wyandot Formation (Upper Cretaceous) and lies upon truncated beds of the Dawson Canyon Formation (Upper Cretaceous). Cut-and-fill relationships characterize a third unconformity developed during Early Tertiary time. A fourth unconformity was developed in Late Tertiary – Pleistocene time by fluvial processes and later by glacial processes. Although in many areas the latest unconformity appears to be the most conspicuous one on the shelf, its configuration closely follows the geomorphic expression developed during the previous period of erosion. The regional extent of the Cretaceous unconformities is not known, and they might only occur near basin margins and on structural and basement highs.
Paleomagnetism and the Origin of Mississippi Valley-Type Ore Deposits
Authors: Beales F. W. , Carracedo J. C. , Strangway D. W.
Published: April 2011

Paleomagnetism can provide useful information about the stratigraphic relationships between the host rocks and the ore of some ore deposits.Four North American mines with stratabound ore deposits of Mississippi Valley type were sampled and the direction and intensity of the natural remanent magnetization (NRM) were measured. Two of the sites sampled (Newfoundland Zinc Co. property near Daniel's Harbour in western Newfoundland and the St. Joe Minerals Co., #8 Mine in southeast Missouri) had a weak, but measurable NRM in both host and ore rocks. This magnetization proved to be highly stable upon alternating field (AF) demagnetization. The other two mines (Magmont Mine, southeast Missouri, and Pine Point Mine, Northwest Territories, Canada) had intensities of magnetization too low to be measured after demagnetization.The pole positions computed for the ores and their corresponding hosts are identical within the statistical uncertainty, strongly suggesting that the ore and the host are, geologically speaking, of roughly the same age. This study gives two reliable pole positions, one for late lower Ordovician dolostone and sphalerite ore from Newfoundland of 26 °N, 126 °E, and the other for the upper Cambrian, based on the Bonneterre dolostone and galena ore from southeast Missouri of 35 °S, 170 °W.Within the present limitations of the method the results agree with published opinions concerning the age of the ore, i.e. that host rock and ore formation were relatively close in time. Therefore, when significant time differences occur between epigenetic ores and their host rocks, the method may be expected to define this. The method will become progressively more valuable as the apparent polar wandering curves for various continental areas become better defined.
Emergent Basalt and Submergent Carbonate–Clastic Sequences Including the Upper Triassic Dilleri and Welleri Zones on Vancouver Island
Authors: Carlisle Donald , Susuki Takeo
Published: April 2011

Rates, depths, and some conditions of accumulation of epipelagic siliceous lime-shale, coarse bioclastic limestone, oceanic basalt flows, pillow lava, and pillow breccia are inferred from new biostratigraphic data, geometry of occurrence, and analogies between major and minor cyclical sequences. Sporadic thin assemblages of intravolcanic beds, pillowed basalt, and flows within the Karmutsen Subgroup reproduce on a minor scale the major sequence of pre-Karmutsen sediments followed by pillow lava, pillow breccia, and flows of the whole Karmutsen. The Dilleri Zone, documented in several new occurrences, includes not only the uppermost Karmutsen, but also almost the entire Quatsino Limestone, an aggregate thickness of 610-920 m, whereas eight ammonoid zones, from Welleri to Lower Suessi, are encompassed by 300-365 m of epipelagic lower Parson Bay Formation. Although recurrent extinction of benthos and increase in proportions of volcanic components, manifest both in microfacies of intravolcanic beds and in the major post-Karmutsen succession (Quatsino Limestone, Parson Bay, and Harbledown Formations), correlate with increasing depth of sedimentation, maximum depths even during deposition of epipelagic lime-shale were probably never more than 60 m. 'Porosity' of pillowed volcanics and aquagene tuff is discussed. The pillow–pillow breccia–flow sequence represents emergent, the sediments, submergent deposition.
Gneissic Alkalic Rocks and Carbonatites in the Frenchman's Cap Gneiss Dome, Shuswap Complex, British Columbia
Authors: McMillan W. J. , Moore Jr. J. M.
Published: April 2011

Frenchman's Cap dome is one of a series of gneiss domes along the eastern border of the high-grade Shuswap metamorphic complex. The granitic gneisses which compose the core of the dome are enclosed in an envelope of metasedimentary rocks.Before Shuswap metamorphism and deformation, the rocks of the sedimentary envelope were intruded by concordant bodies of alkalic rocks and carbonatite. Other carbonatite bodies appear to have formed at or extruded onto the surface. It is not certain whether these are exhalative sedimentary deposits, lava flows, or pyroclastic deposits.Criteria which can be used to distinguish igneous alkalic rocks from those of metasomatic origin were almost entirely destroyed by regional metamorphism. A few relict igneous textures show that at least some of the alkalic gneisses are of igneous origin.
New Fossil Localities and the Base of the Cambrian in Southeastern Newfoundland
Authors: Greene Bryan , Williams Harold
Published: April 2011

In the essentially continuous late Precambrian – Early Paleozoic succession of eastern Newfoundland, abundantly fossiliferous Cambrian shales are separated in most places from underlying strata by a quartzite-siltstone unit. This unit has been referred to the Random Formation in the Avalon-Bonavista area (east) and to the Blue Pinion Formation in the Fortune Bay area (west), and its age and significance in defining a Cambrian-Precambrian boundary have been in doubt for some time. An erosional disconformity at the top of the Random Formation has been interpreted as the base of the Cambrian by most authors. Recent stratigraphic studies indicate that both the Random and Blue Pinion Formations are parts of a laterally continuous lithologic unit and that the upper contact of this unit is gradational and conformable in central parts of its outcrop area. New fossil discoveries both within and beneath the Blue Pinion Formation indicate that the quartzite-siltstone unit is diachronous, and that its westernmost exposures are of Cambrian age.
Ice in Coulthard Cave, Alberta
Authors: Marshall P. , Brown M. C.
Published: April 2011

Coulthard Cave is located in the Crowsnest Pass area of southwestern Alberta, at an elevation of 2650 m above mean sea level. The entrance of the cave faces north, and alt but one of the passages in the cave end in massive ice blockages. Oriented ice samples were removed and studied by crystallographic techniques in a cold laboratory which revealed a layering (not evident to the eye) similar to that formed by the freezing of a horizontal water surface, i.e. a 'pond.' Although present-day temperatures in the cave never exceed 0 °C, large scallop-like depressions in the ice suggest slow erosion by sublimation. An experiment indicated a sublimation rate of 3 mm/yr. Sublimation of the ice permits entrapped sediment to reach the ice surface. Continual downward lowering of the ice surface facilitates the movement by normal trajectory of sediment toward the scallop edges where it forms interstitial ridges. These ridges form on both vertical and overhanging ice surfaces. It is concluded that the ice probably did not form during the Pleistocene Period but rather after the late Hypsithermal warm period.
Thermal History of Rajasthan Pegmatites of India as Revealed by Fission Track Studies
Authors: Nagpal M. K. , Nagpaul K. K.
Published: April 2011

Three cogenetic minerals, namely, muscovites, biotites, and apatites from the Bhilwara (Rajasthan) mica belt of India have been dated by the fission track method. The muscovite ages are ~800 m.y. and the biotite and apatite ages are ~600 m.y. The geological annealing suffered by these minerals has been assessed. The observed discordancies of the ages in the three minerals, each having different annealing characteristics, are interpreted in terms of the thermal history of the region. A cooling rate of ~ 1/4° m.y.−1, after the occurrence of the last major metamorphic activity (i.e. the Delhi orogenic cycle) in the region, has been inferred.