bluuebunny/crossref_metadata_2025 huggingface dataset:
Early Devonian Spores from Central Ellesmere Island, Canadian Arctic
Authors: McGregor D. C.
Published: April 2011

The Vendom Fiord Formation near the head of Cañon Fiord, central Ellesmere Island, hitherto thought to be unfossiliferous, contains mid to late Emsian trilete spores. Strata below the Vendom Fiord Formation, separated from it by an unconformity, contain a less diverse assemblage of spores that suggests a mid to late Gedinnian age. The spores are the only fossils known from these beds, and the first palynomorphs to be reported from the Early Devonian rocks of Ellesmere Island.
Sulfurization of Basalt Under Thermal Metamorphic Conditions to Produce Cordierite-Bearing Rocks
Authors: MacRae N. D.
Published: April 2011

Hydrothermal experiments with fresh basalt in a high pS2 environment yielded cordierite–sulfide-bearing assemblages. These results suggest that during thermal metamorphism of a volcanic exhalative sulfide deposit, progressive sulfurization of the enclosing basalts takes place. Cordierite–anthophyllite and cordierite–andalusite assemblages will result if Fe combines with S to form sulfides and Ca is removed, possibly as CaSO4.
Archean Quench-Texture Tholeiites
Authors: Gélinas L. , Brooks C.
Published: April 2011

Tholeiitic metabasalts and metaandesites from sub-greenschist metavolcanics in the Abitibi volcanic belt northeast of Noranda–Rouyn display delicate and ornamental crystals indicative of rapid or supercooling. These textures compare directly with those observed in modern sea-floor basalts. The textural and chemical data suggest that these Archean rocks may represent a complete (?) section of an island arc, from the deeper stratigraphic levels (mostly monotonous tholeiites) to the more typical island-arc superstructure with intermingled calcalkaline and tholeiitic series. The deeper section can only be a relic of ancient oceanic lithosphere if the Archean sea floor had a wider range in chemistry than the modern-day equivalent.
Fossil Mosses from the Bisaccate Zone of the Mid-Eocene Allenby Formation, British Columbia
Authors: Kuc Marian
Published: April 2011

New fossil taxa (Ditrichites fylesi, Muscites maycocki, M. ritchiei, Palaeohypnum jovet-asti and P. steerei); unnamed moss and moss-like fossils, detrital fragments of various plant tissues, and paleobotanical evidence of the bisaccate zone are described from the Middle Eocene Allenby Formation near Princeton, British Columbia. These remains occur in laminated, tuffaceous, silty and pyroclastic shale, deposited under lacustrine conditions.Detailed examination of the various laminae indicates that beds of white colour and composed of coarser silt grains are poor in fossils and could be related to periods of decreasing bioproduction; less silty and darker coloured beds are rich in macro- and microfossils and could be related to periods of extensive bioproduction. The rock features, lamination, and distribution of macrofossils indicate the slow and undisturbed accumulation of plant remains on a lake bottom.
'Residence' Contamination of K, Rb, Li, and Tl in Diabase Dikes
Authors: Fratta M. , Shaw Denis M.
Published: April 2011

A diabase dike of the Mackenzie swarm has been sampled at two localities where it intrudes basic volcanics and granite respectively. The portion of the dike intruding the granite has statistically significant higher contents of K, Rb, Li, and Tl, as a result of in situ, residence, contamination from the country rock. Ion transfer from the granite toward the diabase took place mainly before the magma crystallized, therefore a process of differentiation was superimposed to that of diffusion.
Numerical Seismograms for Wave Trapping Structures near the Core Boundary
Authors: Waddington Edwin D. , Chapman Chris H.
Published: April 2011

Theoretical amplitudes of diffracted PcP pulses near the geometric edge of the core shadow are important in the determination of earth structure near the core–mantle interface. Frequency domain wave solutions are difficult to apply to earth models with wave-trapping structure near the core. Time domain ray solutions have previously been applied in the illuminated region, and deep in the shadow. A new time domain procedure, including an earth flattening transformation and a ray expansion with the Cagniard–de Hoop ray method, has made it possible to construct numerical seismograms near the geometric shadow edge for a model with a wave-guide structure suggested by seismic array observations at VASA in Alberta.
Temporal Relationships of Rock Units in the Shawinigan Area, Grenville Province, Quebec
Authors: Barton Jr. Jackson M. , Doig Ronald
Published: April 2011

A body of gneissic granite west of Shawinigan, Quebec, yields a Rb–Sr whole-rock isochron of 1258 ± 24 m.y. with an initial 87Sr/86Sr ratio of 0.7034 ± 0.0012. The St-Didace pluton yields a Rb–Sr whole-rock isochron of 1163 ± 51 m.y. with an initial 87Sr/86Sr ratio of 0.7026 ± 0.0006. These isochrons are thought to reflect the original crystallization of these rock units. From these isochrons and the stratigraphic and crystallization histories of these rocks, it may be concluded that: (1) the Grenville Group in this area was deposited prior to 1258 m.y. ago, (2) the first folding recognizable in this immediate area occurred about 1163 m.y. ago, (3) the second recognized folding probably took place about 1124 m.y. ago, and (4) both these deformations probably represent pulses in a common tectonic event, the Grenville Orogenic Event.
Stable Isotope Geochemistry and the Origin of the Great Bear Lake Silver Deposits, Northwest Territories, Canada
Authors: Robinson B. W. , Badham J. P. N.
Published: April 2011

Within the Bear Province, the Echo Bay Group of sediments and volcanics (~1800 m.y.) are intruded by Hudsonian granites and later diabases. Northeasterly trending fracture zones contain vein type U–Ag–Bi–Co–Ni–As–Cu deposits. Samples from the Terra, Norex, Silver Bay, and El Bonanza mines give a general paragenetic sequence of uraninite + hematite; Co–Ni arsenide minerals and silver; dolomite and sulfides; and sulfosalts with bismuth. The vein mineralogy is consistent with an ore fluid of high oxidation potential, low sulfur content (10−3 m) and low pH (~4).Dolomite δ 13C and δ 18O values of around −4‰ (PDB) and +15‰ (SMOW) respectively from all stages reflect a relatively constant temperature of deposition, which from mineralogical and other data is estimated at 200 °C. A δ 18O value of +2‰ (SMOW) is calculated for the ore fluid. The bulk of the sulfide δ 34S values are around +1‰ (CDT), which suggests a magmatic sulfur source. However, an equilibrium model is presented whereby the sulfur is derived from Precambrian sea-water sulfate and the carbon from limestones. The embryo ore fluid (connate sea water?) probably circulated both through the Echo Bay Group and the intrusives, and underwent chemical changes before moving into dilatant zones of mineral deposition.
A Paleomagnetic Reversal in the Osler Volcanic Group, Northern Lake Superior
Authors: Halls H. C.
Published: April 2011

A geological and paleomagnetic study in the Nipigon Strait area, northern Lake Superior, has confirmed previous conclusions drawn from aeromagnetic data, that an unconformity occurs within the Late Precambrian Keweenawan Osler volcanics and separates normally magnetized lavas from older ones with reversed polarity. The new data, together with other paleomagnetic and geological evidence from Keweenawan rocks, suggest that the magnetic reversal occurred when there was a temporary halt or decline in volcanic activity throughout the Lake Superior region. During the quiescent period, coarse clastic sediments were deposited by marginal erosion of the subsiding Keweenawan basin; sinking of the basin with corresponding uplift of the margins may have been greater in the south where the thickest sections of conglomerate and sandstone are preserved.
Glacial Features and Pingos, Amund Ringnes Island, Arctic Archipelago
Authors: Balkwill H. R. , Roy K. J. , Hopkins W. S. , Sliter W. V.
Published: April 2011

Evidence of widespread glaciation of Amund Ringnes Island includes: northwestward-striking grooves and striations in bedrock at three widely separated localities and at elevations of about 60 m, 150 m, and 230 m; and abundant striated erratics, including granite and gneissic rocks. Isolated, sinuous deposits of boulder gravel may be eskers. Dated barnacle shells at approximately 30 m and 35 m above sea level indicate that significant rebound has occurred in the last 8000 to 8500 years, following removal of the ice load.A cluster of small, but well-developed pingos lies on a nearly flat, featureless plain in the central part of the island.
K–Ar Study of the S.P. Flow
Authors: Baksi A. K.
Published: April 2011

The 36Ar content of a 50 m thick lava flow shows minima at a depth of around 37 m, as well as at the bottom chilled margin, suggesting that most of the atmospheric argon entered the solidifying lava flow from the air above it. Measurement of the 36Ar/38Ar ratios indicates that little or no isotopic fractionation occurred during this process. The K–Ar 'isochron' age of the S.P. Flow is about 70 000 years.
40Ar/39Ar Incremental Release Ages of Biotite and Hornblende from Pre-Kenoran Gneisses between the Matagami-Chibougamau and Frotet-Troilus Greenstone Belts, Quebec
Authors: Dallmeyer R. D.
Published: April 2011

Biotite and hornblende from high-grade, granitic gneisses exposed between the Matagami-Chibougamau and Frotet-Troilus greenstone belts in Quebec have been affected by Kenoran metamorphism. Biotites record total gas 40Ar/39Ar ages of 2308 ± 30 m.y. and 2338 ± 30 m.y. Incrementally released gas fractions yield similar plateau ages, suggesting that the biotites have been totally degassed as a result of the thermal event. The ages are interpreted as reflecting the time of post-metamorphic cooling when radiogenic 40Ar began to be retained within biotite. Hornblendes record total gas 40Ar/39Ar ages of 2517 ± 40 m.y. and 2610 ± 40 m.y. Incrementally released gas fractions show a wide deviation from the total gas ages, with a continuous increase in age from low to high temperature release fractions. This lack of correlation suggests that the hornblendes have been only partially degassed by Kenoran metamorphism. However, lack of a high-temperature release plateau indicates that original meramorphic crystallization was older than the ages recorded by the highest temperature release fractions (2599 ± 40 and 2801 ± 40 m.y.). Recognition of an older sialic terrain between these greenstone belts supports recent models proposed for the tectonic evolution of the supracrustal orogenic belts in the Superior Province.
Some Chemical Characteristics and Variations of Gneisses, Intermediate Intrusive Rocks, and Anorthosite in the Lac Rouvray Map-area, Quebec
Authors: Kehlenbeck M. M.
Published: April 2011

A sequence of high-grade gneisses acted as the host for the intrusions of anorthosite and intermediate rocks in the Lac Rouvray area. Based on structural data both these intrusive episodes are closely related spatially as well as temporally.Differentiation trends of the intermediate rocks show enrichment in alkalies relative to iron and magnesia. General agreement exists between the Lac Rouvray series and average calc-alkalic trends of differentiation, suggesting magma generation at considerable depth with emplacement of the intrusions into the crust at some horizontal distance from the most actively deforming part of the orogen.It is now generally accepted that anorthosites are crystal cumulates and therefore compositionally different from their parental magma. Anorthositic rocks have been included in some of the figures for completeness. Owing to their unique composition and general lack of variation, they occupy isolated regions in the projections.High contents of silica typify the gneisses. With increasing silica, variation trends of major oxides are in most respects similar to those of the intermediate suite. Structural and textural evidence, however, demonstrates these rocks to be unrelated.Soda contents for the gneisses and intermediate rocks are nearly constant over a considerable range in potash and lime. Linear decrease in iron and magnesia with increasing alkali content is reflected by all rocks. Anorthositic rocks are restricted to the high-alkali end of this trend, followed by gneisses at lower values of alkalies. The intermediate suite dominates the iron- and magnesia-rich portion of the trend.Potash values for gneisses and intermediate rocks are relatively high over a wide range of silica percentages. Normative feldspar compositions for these rocks, however, show that they are not unusually potassic. Comparison of their alkali-lime indexes shows a significantly higher alkalinity for the intermediate rocks. The index reflects mainly the variations in lime and potash, owing to the nearly constant soda contents.
Étude géochronologique des granites du Massif de Tafraoute (Anti-Atlas marocain)
Authors: Charlot René
Published: April 2011

A detailed study of the Tafraoute area granites points out the existence of a Cambrian granitization (with the present geochronological scale) in the Moroccan Anti-Atlas and allows to define in that granitic massif, up to now considered as an unique one, at least three types of granites with different ages and/or origin (Tafraoute: 530 m.y., Tahala: 1920 m.y., Tarsouat: undetermined).
New Paleomagnetic Results from the Upper Belt – Purcell Supergroup of Alberta
Authors: Evans M. E. , Bingham D. K. , McMurry E. W.
Published: April 2011

Stable remanent directions have been obtained from fifteen sites located in the Purcell, Shepard and Kintla Formations of the upper Belt – Purcell Supergroup. The geomagnetic polarity sequence revealed by these and other studies suggests that the frequency of reversals was probably an order of magnitude lower than that observed over the last few million years. The polarity transitions have considerable potential as regional, and possibly, global, time lines for geological correlation.The paleomagnetic pole obtained (142 °W, 17 °S, dp = 4°, dm = 7°) agrees well with other results from the Belt Supergroup. It falls in a cluster of poles derived from various geological provinces of the Canadian Shield, which may imply that the shield was an integral unit as early as 1400 m.y. ago. However, the constancy of the pole position obtained from Belt rocks thought by some workers to be as young as 1100 m.y. conflicts with the large northward polar excursion (the Logan Loop) derived from other provinces. Possible explanations of this apparent conflict are discussed.
P-Wave Residuals in Western Canada
Authors: Roebroek E. J. , Nyland E.
Published: April 2011

A study of over 1500 P-wave phases which pass, for the most part, through the upper mantle beneath Western Canada, shows that there is no significant lateral variation in P-wave velocity structure beneath Western Canada, and that the Wiggins and Helmberger model for the Western regions of the United States does not fit the data for Western Canada.One possible interpretation of the data for Western Canada is closer to the classical Herrin model of P-wave velocity as a function of depth than it is to the Wiggins and Helmberger A model.
The Avalon Magnetic Lineament—A Possible Continuation of the Triassic Dike System of New Brunswick and Nova Scotia
Authors: Papezik V. S. , Hodych J. P. , Goodacre A. K.
Published: April 2011

A magnetic lineament that cuts across the Avalon Peninsula lies on strike with the Shelburne Dike of Nova Scotia and may represent a northeasterly extension of a system of early Mesozoic dikes and basalts associated with the opening of the Atlantic Ocean. An alternative, but less likely, possibility is that the Avalon Lineament is related to Cambrian dike systems cutting rocks of the Grenville Province.
Layered Granitic Rocks at Chebucto Head, Halifax County, Nova Scotia
Authors: Smith T. E.
Published: April 2011

Structural, mineralogical and textural characteristics of some layered granitic rocks are described. The layers result from the segregation of minerals into bands and lenses of contrasting color and grain size. They were formed near the roof of the pluton prior to final crystallization by flow sorting during episodic shearing generated during intrusion. Comparison of the mineralogy and textures of the layered rocks with those of the main rock types of the pluton shows that the differentiation of the pluton as a whole took place after the formation of the layers by interaction of felsic components concentrated in residual liquids with earlier formed crystals.
Anapetopsis, a new Late Silurian Gastropod from Nova Scotia
Authors: Peel John S.
Published: April 2011

Anapetopsis, a new late Silurian gastropod genus, is described from the Stonehouse Formation of Arisaig, Nova Scotia. Two new species, A. maclearni and A. lalajae, are assigned to the genus which displays a widely expanded aperture possibly reflecting association with a soft substratum.
Pre-Kenoran Tonalitic Gneisses in the Grenville Province
Authors: Frith R. A. , Doig R.
Published: April 2011

Rb–Sr whole-rock studies of tonalitic gneiss within the Grenville Province on the eastern extension of the Abitibi fold belt may indicate an age greater than 3000 m.y. The gneiss samples were collected up to 32 miles (52 km) from the Grenville Front. Rocks beyond this generally show the effects of the Grenvillian orogeny about 1100 m.y. ago which raised the 87Rb/86Sr initial ratio from about 0.7025 to 0.7148. Rocks more than 40 miles (64 km) from the Grenville Front show retrograde metamorphism from the granulite facies that is considered to be related to the metamorphism associated with the intrusion of anorthosite still farther to the southeast (ca. 1500 m.y.). The Archean tonalitic gneisses exhibit E–W and NE–SW aeromagnetic trends but similar rocks to the southeast exhibit aeromagnetic patterns that are chiefly N–S and may be a result of Hudsonian deformation. A small granitic body in this zone of N–S aeromagnetic pattern was intruded 1745 ± 23 m.y. ago(87Rb λ = 1.39 × 10−11y−1).
A Syenitic Pluton of Archean Age within the Grenville Province of Quebec
Authors: Doig Ronald
Published: April 2011

The Dorval syenite intrudes quartzofeldspathic gneisses some 35 km southeast of the Grenville Front, between Val d'Or and Montreal. The whole-rock isochron age of 2548 m.y. (initial 87Sr/86Sr ratio of 0.7038) for the syenite stock also establishes the existence of gneissic rocks of Archean derivation at this distance from the Front, and may date the early metamorphism and deformation of these rocks at some time prior to 2550 m.y. ago.
The Twillingate Granite and nearby Volcanic Groups: An Island Arc Complex In Northeast Newfoundland
Authors: Williams Harold , Payne John G.
Published: April 2011

The Twillingate Granite cuts mafic pillow lavas and silicic fragmental volcanic rocks of the Sleepy Cove Group. The granitic rocks are soda-rich and they vary from intensely foliated and mylonitic in the south to mildly foliated and massive toward the north. The Sleepy Cove volcanic rocks show similar structural and metamorphic variations from lineated amphibolitic pillow lavas, to elongated pillows of greenschist metamorphic grade, to slightly metamorphosed and relatively undeformed pillow lavas.The collective terrane occupied by the Twillingate Granite and Sleepy Cove Group is virtually surrounded by intrusive mafic dikes that are integral and coeval parts of the Moretons Harbour and Herring Neck Groups. The dikes decrease in abundance away from the contacts of the collective Twillingate – Sleepy Cove terrane. The essentially intrusive contact is modified by faults and locally, the profuse dike swarms are absent.Regional relationships, thickness, lithofacies, and petrochemistry all indicate that the Moretons Harbour and Herring Neck Groups relate to an episode of Lower Ordovician island arc volcanism. Intrusive relationships and contrasts in structural style and metamorphic grade indicate that the Twillingate Granite and Sleepy Cove Group are older. These older rocks are also interpreted as island arc derivatives, so that in their present position, they may represent the remnant of a partly deformed and metamorphosed older arc that is now bordered by relatively undeformed Lower Ordovician volcanic rocks.Similar relationships within transported sequences of western Newfoundland suggest a central Newfoundland island arc provenance for the transported Little Port Complex.
Sur quelques Chitinozoaires ordoviciens du Québec et de l'Ontario, Canada
Authors: Martin Francine
Published: April 2011

Rich Chitinozoa assemblages of the Trenton Group and of the Utica Formation at the Montmorency Falls (Province of Quebec) are compared to an assemblage of the Eastview Formation, at Ottawa (Province of Ontario). Fourteen species of which three are new (Conochitina naevia, C. kjellstromi and Ancyrochitina barbescens), and three subspecies are described.
Marginal Basins of the Labrador Sea and the Davis Strait Hot Spot
Authors: Hyndman R. D.
Published: April 2011

There are deep marginal sedimentary basins in the Labrador Sea extending to the region of Davis Strait. In contrast, the central part of the Sea shoals toward Davis Strait. The difference is explained by the central part of the Sea being formed while the Davis Strait hot spot was active, producing increased vulcanism and crustal thickness. The sea floor along the margins was produced before the hot spot became active about 60 m.y. ago, so has normal crustal thickness and thus normal basement depth.
Advancing Rock Glaciers in the Lake Louise Area, Banff National Park, Alberta
Authors: Osborn Gerald D.
Published: April 2011

Study of aerial and ground photographs shows that three rock glaciers in the vicinity of Lake Louise in Banff National Park, Alberta have been advancing during the last 70 years. They are now overriding a lateral moraine of the Victoria glacier. Lichenometry and rate/length calculations indicate that the rock glaciers originated within the last several centuries. Rates of advance between 1947 and 1974 average 0.3 to 0.6 m/y.
Paleomagnetism of the Flin Flon – Snow Lake Greenstone Belt, Manitoba and Saskatchewan
Authors: Park J. K.
Published: April 2011

The Flin Flon – Snow Lake greenstone belt is of Archean or Aphebian age and has been metamorphosed to greenschist or low amphibolite facies during the Hudsonian orogeny. It contains four rock units — the Amisk Group, the Missi Group, metadiorite and metagabbro bodies, and the Boundary Intrusions. The rocks contain two main magnetizations, an early B magnetization and a later A magnetization. Both magnetizations contain reversals. The A magnetization (43 sites, direction 168°, +73°, k = 17, α95 = 5°, pole 24°N, 095°W) is found in all rock units. It can be divided into three parts (1, 2 and 3) which have the same general direction, but which are significantly different from one another. It is suggested that A1 is a viscous partial thermoremanence (vptrm), and A2 possibly a chemical remanence (crm). Both are considered to have been acquired during uplift (1600–1700 m.y.) following the Hudsonian orogeny. A3 is possibly a crm acquired during late fault movements and appears to be carried by hematite developed during retrograde metamorphism. A3 is considered to be about 1600 m.y. old. The B magnetization (7 sites, 129°, +04°, k = 12, α95 = 18°, pole 20°S, 046°W) occurs in all rock units except the Missi. It is particularly well developed in the Boundary Intrusions where it is considered to be a primary thermoremanent magnetization (trm). In other rock units B is considered to be a vptrm acquired during heating at the time of emplacement of the Boundary Intrusions. The B magnetization is considered to be about 1800 m.y. old. Some enigmatic magnetizations with very high blocking temperatures above 700 °C were observed. Formulas for calculating the coercivities in rocks with more than one magnetization are given.
Development of Cleavages within Diamictites of Southeastern British Columbia
Authors: Ross John V. , Barnes William C.
Published: April 2011

Deformed diamictites and associated sediments of the lower part of the Upper Proterozoic Windermere Group have been examined on all sides of the Purcell geanticline of southeastern British Columbia. In all areas examined the rocks are characterized by two early cleavages having a variable angle between them of 10° to 35°; the earlier of the two cleavages is always slaty, whereas the second may be slaty or fracture with offset, according to lithology.Clasts are aligned parallel to both cleavages; those parallel to the earlier cleavage have extension features perpendicular to both cleavages. Mineral overgrowths at the strain shadows of clasts are parallel to both cleavages and show similar time relations. Clast rotation, variation in flattening strain, and the earlier slaty cleavage with associated mineral growth are present throughout the whole region and were probably initiated by low angle buckling of water-saturated sediments. Continued buckling might have brought about further dewatering; associated flattening apparently gave rise to the second cleavage and mineral overgrowth, to rotation of the earlier cleavage, and to further rotation of some clasts parallel to the new cleavage.
A Spinner Magnetometer for Susceptibility Anisotropy in Rocks
Authors: Boetzkes P. C. , Gough D. I.
Published: April 2011

The study of rock fabric through the anisotropy of magnetic susceptibility requires instruments capable of high-precision measurement of weakly magnetic sedimentary rocks. The magnetometer here described is such an instrument. The rock specimen spins on a shaft in an air-gap in a closed magnetic circuit of permalloy with barium ferrite permanent magnets. The air-gap is designed to apply to the rotating specimen a very uniform flux density with a value of 0.115 tesla when the magnets are saturated. Magnetizing coils integral to the transducer are used to magnetize or demagnetize the permanent magnets. Coils in the specimen gap detect specimen magnetization parallel and perpendicular to the applied field. The magnetic circuit forms a balanced bridge and allows alternative modes of transduction. The design is such that Nyquist noise is the largest noise contributed by the magnetic circuit and is smaller than the Johnson noise from the detector coils. Measured noise from the completed transducer is only 4.7 dB above the Johnson noise. The limiting sensitivity is, however, set by the time variation of anisotropy signal from the shaft and empty specimen holder. This limit is at 1.5 × 10−9 mksu (1.2 × 10−10 emu/cm3), so that relative anisotropy of 0.01% can be detected in a weakly magnetic sandstone of bulk susceptibility 1.5 × 10−5 mksu. Calibration is discussed and sample measurements are presented. Construction of the transducer required solution of many technological problems, of which the greatest was encapsulation to suppress all vibration of parts without strain-induced loss of permeability of the permalloy. The more important of the solutions found are outlined briefly.
Dinosaur Tracks, Columbosauripus ungulatus (Saurischia: Coelurosauria), from the Dunvegan Formation (Cenomanian) of Northeastern British Columbia
Authors: Storer John E.
Published: April 2011

Columbosauripus ungulatus Sternberg is identified from the Dunvegan Formation, Cenomanian (early Upper Cretaceous) of East Pine, northeastern British Columbia. The species was originally reported from the Gething Formation, Albian (late Lower Cretaceous) of Peace River canyon, British Columbia.
Radial Variation of Magnetic Properties in Submarine Pillow Basalt
Authors: Ryall Patrick J. C. , Ade-Hall J. M.
Published: April 2011

A detailed study has been made of the magnetic properties of four pillow lavas of differing ages from the Mid-Atlantic Ridge crest at 45°N. The pillows show radial variations in grain size and concentration of titanomagnetite due to the initial cooling history, and radial variation in their degree of titanomagnetite oxidation due to low temperature alteration by sea-water. The degree of titanomagnetite alteration not only increases from the interior to the exterior of the pillows, it also increases from the youngest to the oldest. Radial variation in NRM intensity results in average values for the pillows of as little as half the values for the freshest parts. The direction of the original NRM has been maintained throughout the alteration.
Sedimentary Environments and Late Quaternary History of a 'Low-Energy' Mountain Delta
Authors: Smith Norman D.
Published: April 2011

Due to its low input of coarse sediment, Upper Waterfowl Lake, in Banff Park, Alberta, has developed a delta atypical of lacustrine deltas in this high mountain region: lack of foresets, vertically aggrading stable distributary channels, and a surface composed of mostly fine-grained floodplain materials. Deltaic progradation has outrun the supply of coarse sediment, resulting in entrapment of all gravel and coarse sand in proximal channels.Data provided by auger samples, including stratigraphic positions of Mazama and Bridge River volcanic ashes, suggest the lake was formed about 8800 years ago when deposition of a large alluvial fan blocked the Mistaya River at the upper end of Lower Waterfowl Lake. The delta has undergone two progradations, one beginning at the lake's time of origin, the other following a renewed lake level rise some 2300 years ago. Mean aggradation rates since Mazama time (6600 y BP) have been approximately steady at about.05 cm/y. Pre-Mazama lake sediments, however, were deposited more than twice as fast as a result of accelerated sedimentation rates that accompanied deglaciation.
Seismic Reconnaissance of Lake Melville, Labrador
Authors: Grant A. C.
Published: April 2011

Seismic profiler transects indicate that much of Lake Melville is underlain by sedimentary strata, which are probably an extension of the (Proterozoic? Paleozoic?) Double Mer Formation, exposed onshore to the northwest. The southeastern limit of these strata in Lake Melville is inferred to lie beneath the linear zone of deep water along the southeast shore. Unconsolidated sediments beneath this linear deep attain apparent thicknesses of nearly 400 m, so that the underlying bedrock surface is at least 600 m below the present sea level. The Lake Melville depression is thus overdeepened more than one-half a kilometre with respect to its outlet east to the Labrador Sea.
Stratigraphic revisions of the Nicola, Cache Creek, and Mount Ida Groups, based on conodont collections from the western margin of the Shuswap Metamorphic Complex, south-central British Columbia
Authors: Okulitch A. V. , Cameron B. E. B.
Published: April 2011

Conodonts have been recovered from highly deformed limestone and calcareous argillite in Palaeozoic and Mesozoic successions near the western border of the Shuswap Metamorphic Complex. Presently known biostratigraphic sequences indicate that the Eagle Bay Formation of the Mount Ida Group is in part Mississippian in age, and likely correlative with the Slide Mountain and Milford Groups. In addition, part of the succession previously mapped as Cache Creek Group in the Vernon area is now known to be Late Triassic in age, and can be correlated with the Sicamous Formation of the Mount Ida Group, the Nicola Group, and the Slocan Group. The Upper Triassic succession was affected by deformation and metamorphism associated with development of the Shuswap Metamorphic Complex.
Contemporary rates of bedrock weathering, Sudbury, Ontario
Authors: Pearce Andrew J.
Published: April 2011

Mean rates of in situ disintegration of quartzite and gabbro (5 plots for each rock type) in defoliated areas near Sudbury, Ontario, during the period from May 1971 to May 1973 were:[Formula: see text]Coefficients of variation for the four rock type – measurement period combinations range from 83% to 111%.Differences in disintegration rate between rock types are not significant at greater than a 70% confidence level in either year of study, and differences between the two years of study are not significant at greater than an 80% confidence level for either rock type.Comparison of the results of this study with published data on total denudation rates in vegetated areas of similar climate and relief suggests that bedrock weathering in the study area is not proceeding at a greatly abnormal rate.
A magnetic model for the Budgell Harbour Stock, Newfoundland
Authors: Miller H. G.
Published: April 2011

A detailed analysis of the aeromagnetic data over the Budgell Harbour Stock indicates that the stock can be modelled as a vertical prism having a depth to the bottom of approximately 5.5 km. The depth of the body has been calculated using the measured magnetic susceptibility and NRM data for 6 sample sites from the stock. The modelling results indicate that the apparent susceptibility determined from the surface rock samples are too small to explain the observed anomaly. This indicates that the true apparent susceptibility for the stock is larger than the observed apparent susceptibility.
The Davis nepheline pegmatite and associated nepheline gneisses near Bancroft, Ontario
Authors: Sylvester G. C. , Anderson G. M.
Published: April 2011

The Davis pegmatite consists largely of albite with some nepheline and biotite, and minor amounts of microline and several other minerals. It is discordant to a series of gneissic nepheline-amphibolites and plagioclase–nepheline–biotite–hastingsite–calcite gneisses. These rocks have been sampled by about 150 m of diamond drill core. Analyses of this material are interpreted to mean that the present composition of the pegmatite cannot be the direct result of magmatic crystallization. It is suggested that post-magmatic metasomatism has exchanged Na for K and Fe for Mg, among other changes, and this is consistent with the mineral textures observed.
Rb/Sr Ages and a profile of initial Sr87/Sr86 ratios for plutonic rocks across the Yukon Crystalline Terrane
Authors: Couteur P. C. Le , Tempelman-Kluit D. J.
Published: April 2011

Nine Rb/Sr apparent ages are reported for igneous rocks of the Yukon Crystalline Terrane. The oldest age (144 m.y.) is from the Triassic? Klotassin quartz diorite and is thought to be a hybrid age that probably reflects the effects of younger intrusives on rocks at least 190 m.y. old. Five ages of about 100 m.y. presumably reflect the cooling of the Coffee Creek quartz monzonite. K/Ar ages for this event are slightly younger than the Rb/Sr ages, suggesting slow cooling. Rb/Sr ages of 53 and 67 m.y. were obtained for the Ruby Range batholith and an age of 61–67 m.y. for the Nisling Range alaskite. The Rb/Sr ages obtained generally confirm recently determined K/Ar ages. There is a regional decrease in initial Sr87/Sr86 ratios, southwestward across the Yukon Crystalline Terrane. This may mean that Precambrian rocks extend under the Yukon Crystalline Terrane, but are absent under the adjoining Coast Plutonic Complex.
Middle Devonian brachiopods from the Bird Fiord Formation of Bathurst Island, Arctic Canada
Authors: Johnson J. G. , Perry D. G.
Published: April 2011

Seven brachiopod species are described from the Middle Devonian Bird Fiord Formation of central Bathurst Island. Costacranaena is a new genus. Schizophoria sulcata, Cupularostrum repetitor, and Costacranena marlenae are new species.The described Bird Fiord fauna occupied a shallow turbid biotope and belongs to an as yet undescribed community. It correlates to the fauna from the mid- or upper Hume Formation of western Canada and is of probable late Eifelian age.
Pattern of recent vertical crustal movements in Maritime Canada
Authors: Vaníček Petr
Published: April 2011

A surface depicting linear vertical movements in Maritime Canada was computed from sea-level data recorded by 8 tide guages and 308 mostly disjoint, relevelled segments of the first-order Canadian levelling network. Owing to the sparsity of the available data and their distribution, the velocity surface must be regarded as indicative of the crude features only. The indications are that there is a west-northwest trending belt of faster subsidence across the eastern end of the Bay of Fundy, and that there may be an area of uplift in northeastern New Brunswick. Although the faster subsidence around the eastern Bay of Fundy seems to be well established now, more data are needed to prove or dispel the existence of the indicated uplift.
A Rb–Sr whole-rock isochron from the Otto stock, Ontario
Authors: Bell K. , Blenkinsop J.
Published: April 2011

A redetermination of the age of the Otto stock by the whole-rock Rb–Sr isochron method indicates an age of 2160 ± 80 m.y., a figure that is substantially greater, by about 450 m.y., than the previously quoted value. This age, which is almost identical to the generally accepted value for the Nipissing diabase, appears to be consistent with both geological and palaeomagnetic observations.
Geophysical and geological trends on the Continental Shelf off northeastern Newfoundland
Authors: Jacobi Robert , Kristoffersen Yngve
Published: April 2011

Geophysical data collected by R/V VEMA in 1973 on the shelf off northeastern Newfoundland together with data from other sources is used to define the offshore continuation of basement geophysical trends associated with the Appalachian orogen. A prominent gravity low associated with the Gander tectonic–stratigraphic zone continues offshore with a northeasterly trend to 50°N and possibly to 51°N. A pronounced magnetic low of similar trend appears as a nearly continuous feature from north of Fogo Island to the shelf edge. This and several other magnetic anomalies that trend northeast are oblique to an east-northeast striking fault of a post-middle Paleozoic and pre-Early Cretaceous age. An anticlinal sedimentary structure associated with a negative gravity anomaly with steep gradients at 50.77 °N, 53.75 °W may be a diapir.
A preliminary comparison of the composition of bluffs and sediments from Lakes Ontario and Erie
Authors: Kemp A. L. W. , Dell C. I.
Published: April 2011

The natural pre-industrial background composition of Lakes Ontario and Erie sediments is compared with the modern contaminated sediment and with the shoreline bluff materials. Quartz, carbonates, feldspars, and clay minerals are the dominant minerals in the bluff samples. The carbonate-carbon content of the bluff samples is generally high, averaging 2.4% of the sample weight. Calcite and dolomite are the predominant forms of carbonate in bluffs. However, the carbonate-carbon of the pre-industrial sediment is low, averaging around 0.6%. The depletion of carbonates in the offshore sediments is due to their solution during transport and deposition. Ca follows the same trend as carbonates in all the samples. Mg is also depleted in the lake sediments, reflecting a decrease in dolomite from the bluffs to the sediments.Feldspars, which are a dominant mineral in the bluff samples, are only present in small amounts in the offshore sediments. Na is also depleted in the sediments. It is not certain if the decrease in Na from the bluffs to the sediments is due to weathering or sorting of feldspars during transport and deposition.Organic-C, N, Mn, P, Hg, Pb, Zn, Cu, Cd, Be, and V are all highly enriched in the modern sediments relative to the bluffs and the pre-industrial sediments. With the exception of Mn, the enrichments of these elements is due to anthropogenic inputs.
Note on the age of the Giant Mascot ultramafic body, near Hope, B.C.
Authors: McLeod J. A. , Vining Mark , McTaggart K. C.
Published: April 2011

K/Ar ages from the Giant Mascot ultramafic body (119–95 m.y.) suggest that it is slightly older than adjacent diorite and tonalite (79–89 m.y.), which are shown to be members of the mid-Cretaceous Spuzzum Intrusions.
Trace metals in the waters of the Saguenay fjord
Authors: Yeats P. A. , Bewers J. M.
Published: April 2011

The distributions of the trace metals iron, zinc, copper, nickel, cobalt, and cadmium in the Saguenay fjord have been determined during the spring freshet. Whereas the mean concentrations of copper, nickel, and zinc are only slightly higher than those in the northwest Atlantic Ocean, the levels of cadmium and cobalt are about three to six times higher, and iron up to two orders of magnitude higher, than ocean water. The significant enrichment of all these metals, with the exceptions of zinc and cadmium, in the surface water relative to the intermediate depth water reflects runoff inputs. The concentrations of total and dissolved iron decrease with increasing salinity, but the nonlinearity of the relationships between the metal concentrations and salinity indicates that significant quantities of iron are lost from the water column in the fjord. Except near the head of the fjord, where flocculation and sedimentation processes appear to be removing large quantities of river-borne iron, iron comprises a constant 11% of the suspended particulate matter. The residence time and budget for iron in the larger western basin of the fjord indicate that 47% of the iron that enters the basin is rapidly removed to the underlying sediments.
A coring method for lake surface sediments
Authors: Strong Wayne L. , Cordes Lawrence D.
Published: April 2011

A technique for coring flocculent limnic sediments, involving the use of a Livingstone piston sampler and dry ice is described. The technique is most useful when detailed stratigraphic analysis of surface sediments is important.
Potassium–argon geochronology of the Poohbah Lake alkaline complex, northwestern Ontario
Authors: Mitchell Roger H.
Published: April 2011

The Poohbah Lake complex is an Archean undersaturated potassic pluton consisting of porphyritic syenite, malignite, amphibole syenite, and biotite–pyroxenite, intrusive into Couchiching metasediments. Apparent K–Ar ages for biotites from the alkaline rocks fall into two groups, one (2 samples) with ages greater than 2700 m.y., the other (8 samples) forming a tight cluster of ages at 2556 ± 36 m.y. This latter group defines a K–Ar isochron age of 2706 ± 23 m.y. The data are interpreted to imply that the isochron age and the ca. 2700 m.y. apparent ages record the cooling age of the complex and that the majority of samples were subjected to a later thermal event which resulted in loss of equal amounts of Ar from each sample, this event being correlated with epeirogenic strike-slip faulting. Algoman granite and pegmatite (3 samples), which on geological evidence was emplaced later than the alkaline rocks, gives apparent K–Ar ages of 2550–2630 m.y. Algoman mica samples plot on the alkaline rock isochron giving 2702 ± 24 m.y. as a minimum age for plutonism in this area.
Sedimentology of the Dezadeash flysch and its implications for strike-slip faulting along the Denali Fault, Yukon Territory and Alaska
Authors: Eisbacher G. H.
Published: April 2011

The Dezadeash Formation of Late Jurassic – Early Cretaceous age is a flysch sequence with a thickness of about 3000 m. It consists of turbidites, mass-flow deposits, and argillite. Most of the formation was deposited on a deep-sea fan system fed by an uplifted volcanogenic terrane to the west. Along its western border, the Dezadeash flysch is truncated by the Denali Fault; towards the east, part of the Dezadeash Formation seems to have been metamorphosed into the Kluane Schist.It is suggested that both the Dezadeash flysch and Kluane Schist have been torn apart by the Denali Fault and that equivalent rock units are found within the Nutzotin Mountains Sequence and the McLaren Metamorphic Belt of Alaska. A dextral displacement of 300 km could account for the present distribution of these units along the Denali Fault. This offset was probably achieved during mid-Tertiary time.
Age and style of mesostructures in north-central Gaspé, Quebec
Authors: Romer H. S. de
Published: April 2011

Three main geological units are distinguished in the Mount McGerrigle area of north-central Gaspé, each different in lithology, structural style, and age: a Cambro-Ordovician, complexly deformed assemblage of eugeosynclinal rocks is discordantly intruded by a composite pluton, and is unconformably overlain by mildly deformed Silurian–Devonian platform deposits. Three phases of deformation (F1, F2, F3) have affected the Quebec and Schickshock Groups of Cambro-Ordovidian age. The F1, deformation was accompanied by lowgrade regional metamorphism resulting in a penetrative planar fabric. The F2 deformation deformed pre-existing structures and produced the prevalent northeasterly trending and shallowly plunging folds. The third phase was least penetrative, resulting in broad and upright east-northeasterly striking F3 folds that modify the orientation of F2 structures. The forcefully injected Mount McGerrigle pluton, a late intrusion of the Acadian orogeny, truncates and deforms the F1 and F2 fabric elements of the Cambro-Ordovician rock. Multiphase deformation thus preceded the Acadian orogeny in the area. Silurian–Devonian rocks, on the other hand, have been affected only by the F3 deformation during the Acadian orogeny.
Preliminary interpretation of a marine deep seismic sounding survey in the region of Explorer ridge
Authors: Clowes R. M. , Malecek S. J.
Published: April 2011

A marine seismic system for recording near-vertical incidence to wide-angle reflected waves and refracted waves with penetration from the ocean bottom to the upper mantle (deep seismic sounding or DSS) has been developed. Signals from six individual hydrophones suspended at 45 m depth from a 600 m cable trailed behind the receiving ship are recorded in digital form. Using charges ranging from 2.3 to 280 kg, two reversed DSS profiles were recorded in the region of Explorer ridge during 1974. A preliminary interpretation of the profiles based on first-arrival information in the range 4 to 80 km has been made.The reversed profile run across the ridge showed no anomalous effects as the ridge was crossed; the profile on Juan de Fuca plate, paralleling the ridge, exhibited traveltime branch offsets and delays. These have been interpreted as due to faulting with a vertical component of offset of about 4 km. The reversed upper mantle velocities are 7.85 and'7.30 km/s indirections perpendicular and parallel to the ridge. Anisotropy is proposed to explain these different velocities and gives a 7% anisotropic effect. The data require that 'layer 2' comprise at least two layers with velocities of 4.13 km/s and 5.25 km/s and individual depth extents ranging from 1 to 2 km. Compared with crustal sections from other ridge areas, the interpretation gives a thick 'layer 3' (up to 6 km) near the ridge crest. The sub-bottom thickness of the oceanic crust varies between 7 and 9 km, except in the faulted region, where the 7.30 km/s material is present less than 3 km from the bottom.
Impulse radar experiments on permafrost near Tuktoyaktuk, Northwest Territories
Authors: Davis J. L. , Scott W. J. , Morey R. M. , Annan A. P.
Published: April 2011

Field trials with a VHF impulse radar have been undertaken in the Tuktoyaktuk, N.W.T. area during the summer of 1973 and the spring seasons of 1974 and 1975. The radar transmits a wavelet with a centre frequency of 110 MHz and a pulse duration of 18 ns. Separate transmitter and receiver antennas were used.Preliminary interpretation of the data obtained at the Involuted Hill test site indicates that ice/sand interfaces were detected to ranges greater than 30 m. In icy sand, ice lenses separated by 3 m were resolved. Clay-till/ice interfaces were not detected at ranges greater than about 3 m. At other sites near the village of Tuktoyaktuk, sand/clay-till interfaces were detected at ranges greater than 5 m.Wide angle reflection and refraction sounding yields estimates of reflector depths and propagation velocities. Radar has proven useful in delineating geologic structure, but bore-hole control is required for identification of the geological composition of the structure.