bluuebunny/crossref_metadata_2025 huggingface dataset:
Origin of the Tulameen ultramafic-gabbro complex, southern British Columbia
Authors: Findlay D. C.
Published: April 2011

The Tulameen Complex is a composite ultramafic-gabbroic intrusion that outcrops over 22 sq. mi. (57 km2) in the Southern Cordillera of British Columbia. The complex intruded Upper Triassic metavolcanic and metasedimentary rocks of the Nicola Group, and on the basis of geologic relations and a K–Ar age determination (186 m.y.) is tentatively dated as Late Triassic.The principal ultramafic units — dunite, olivine clinopyroxenite, and hornblende clinopyroxenite — form an elongate, non-stratiform body whose irregular internal structure is best explained by deformation contemporaneous with crystallization of the rocks. The derivation of the ultramafic rocks is attributed to fractional crystallization of an ultrabasic magma. The gabbroic mass, which consists of syenogabbro and syenodiorite, partly borders and partly overlies the ultramafic body and was apparently intruded by it.The ultramafic and gabbroic parts of the complex probably formed from separate intrusions of different magmas, but the two suites have sufficient mineralogical and chemical features in common to indicate an ultimate petrogenic affinity of the magmas. Comparison of the Tulameen rocks with nearby intrusions of the same general age, in particular the Copper Mountain stock, suggests that they are members of a regional suite of alkalic intrusions. The possibility is also raised that these intrusions may be comagmatic with the Nicola volcanic rocks.
An interpretation of gravity measurements on the west coast of Canada
Authors: Stacey R. A. , Stephens L. E.
Published: April 2011

The survey area lies close to the continental margin and includes parts of the Insular Tectonic Belt and the Coast Mountains igneous and metamorphic complex, which are part of the Cordilleran (geological) Region. In an endeavor to clarify the structure of the Insular Tectonic Belt and the Coast Mountains complex, gravity measurements have been made using Worden or LaCoste and Romberg meters at 12–15 km intervals throughout the Queen Charlotte Islands, Vancouver Island, and the coastal areas of the British Columbia mainland. Measurements have been made at the same interval using a LaCoste and Romberg underwater gravity meter wherever the depth of water is less than 300 fathoms (< 540 m) along the fiords of the mainland coast and over the continental shelf. The observed gravity values have been reduced to Bouguer anomalies and terrain corrections have been calculated using either Bible's tables or a computer system based on the attraction of the rectangular prismatic block.The major features of gravity field are: (1) a positive Bouguer anomaly along the western edge of the area, which is associated with the change from continental to oceanic crust, and (2) a negative anomaly along the Coast Mountains, which is attributed to the thickening of the continental crust below these mountains. On the eastern side of the Queen Charlotte Islands, Hecate Strait, Queen Charlotte Sound, and Vancouver Island, the average Bouguer anomaly is approximately zero, with local anomalies superimposed on a fairly flat gravity field. Several of these local anomalies are related to density variations in the surface rocks.
Correlation of radiometric ages of Nipissing diabase and Huronian metasediments with Proterozoic orogenic events in Ontario
Authors: Fairbairn H. W. , Hurley P. M. , Card K. D. , Knight C. J.
Published: April 2011

Field evidence shows that the Huronian section of metasediments in Ontario is younger than the Archean and older than the Nipissing diabase. Previous radiometric investigations show the age of the latest Archean granitic intrusions to be about 2500 m.y. and the Nipissing diabase to be 2155 ± 80 m.y. In this paper we present whole-rock Rb–Sr data which (1) confirm the age of the diabase in a single sill at Gowganda (2162 ± 27 m.y.), and (2) show the age of the Gowganda Formation (which the sill intruded) to be 2288 ± 87 m.y. In marked contrast metasediments and metavolcanics in the Huronian section southwest of Sudbury show younger ages ranging between 1800 and 2200 m.y. This is interpreted in terms of known orogenic disturbance of the Huronian rocks south and west of Sudbury and its absence in the Cobalt–Gowganda area to the northeast. Both minerals and whole rocks have responded by showing low and discordant ages in the disturbed area. The higher and accordant ages in the undisturbed environment agree with the geologic succession and are believed to be the true ages of these rocks.
Rock cataloguing made easy with Keysort cards
Authors: Erdosh George
Published: April 2011

Systematic cataloguing of rocks is essential for both teaching and research. A simple cataloguing system is proposed using hand-sorted punch cards that should be satisfactory for collections containing items up to a few tens of thousands. In addition to punching, the cards as well as the specimens are filed according to a certain system in order to facilitate the quick finding and refiling of any number of specimens.
Theoretical response of a seismograph at Yellowknife, Northwest Territories, to an underground explosion at the Nevada test site
Authors: Hasegawa H. S. , Whitham K.
Published: April 2011

A comparison of the theoretical response of the short-period, vertical-component seismograph at Yellowknife to an underground explosion originating at the Nevada Test Site with a real seismogram indicates that the prime contributors to complexity are likely due to the following: (a) complex crustal reverberations at the N.T.S., (b) different phase arrivals, and (c) signal-generated noise at Yellow knife.
On an immature specimen of Kritosaurus notabilis (Lambe), (Ornithischia: Hadrosauridae) from the Upper Cretaceous of Alberta, Canada
Authors: Waldman M.
Published: April 2011

A juvenile hadrosaurine dinosaur, Kritosaurus notabilis (Lambe), is described from the Oldman Formation, Upper Cretaceous, Alberta. It is evident that the characteristically broad skull-roof of this genus is not developed until the individual is more than half-grown, and that this is probably true for other hadrosaurines. The status of the species of Kritosaurus is reviewed, and it is considered that K. incurvimanus may be an immature K. navajovius. The nomenclature of the anterior part of the neurocranium is discussed briefly, the element formerly described as a presphenoid being now designated as the septosphenoid interorbital septum.
Stochastic model for the deposition of varves in glacial Lake Barlow–Ojibway, Ontario, Canada
Authors: Agterberg F. P. , Banerjee I.
Published: April 2011

Various methods of time series analysis have been applied to thickness data obtained from eight measured sequences of varves belonging to the Pleistocene glacial Lake Barlow–Ojibway in northern Ontario. Both sedimentological evidence and the results of the statistical analysis support Kuenen's model for varve deposition by turbidity currents.Proximally, individual varves merge with the crossbedded deltaic sands and gravel of eskers. Distally, they change successively from sandy to silty, and then to diamictic facies. Both the silt (summer) and the clay (winter) layers in a varve couplet show an approximately exponential decrease in thickness away from the icefront. This trend is more conspicuous in the silt. The genetic difference between the silt (deposited by turbidity currents) and the clay (deposited out of suspension) is reflected in marked differences in the statistical behavior of their thickness-time series.The thickness variations of both silt and clay layers can be considered as the sum of a gradual, systematic variation (signal) and a random variation (noise). When the effect of the thinning away from the icefront and that of the superimposed noise are eliminated, both the silt and clay residual thickness data satisfy a Markov model of the second order. This model is shown to be related to variations in the rate of retreat of the icefront. Besides the second-order Markov process, two weakly-developed short-term cycles have also been detected.
Paleomagnetism of four late Miocene gabbroic plugs in south-central British Columbia
Authors: Symons D. T. A.
Published: April 2011

A paleomagnetic study was made of 101 cores from 20 sites representing about equally 4 small olivine gabbro plugs which intrude tectonically undisturbed olivine-rich plateau basalts of late Miocene age in the southern Cariboo region of south-central British Columbia. After alternating-field cleaning, statistical analysis of the stable remanence indicates that the site mean directions are significantly distinct within each plug so that even such small intrusive bodies (250–800 ft (78–248 m) in diameter) must be thoroughly sampled to derive a representative mean remanence direction. Both Tin Cup Mountain and Lone Butte plugs have normally polarized remanence, whereas Mount Begbie and Forestry Hill plugs have reversely polarized remanence. Statistical analysis indicates that these plugs were emplaced over a short span of geologic time of possibly less than 1 × 106 years and that at least three polarity intervals are represented. The geomagnetic pole position computed from the normalized site mean directions is 146.7 °W, 84.9 °N (δp = 4.8°, δm = 5.5°). This pole position is almost coincident with the pole position determined for the surrounding plateau basalts, and it is consistent with those obtained from other Miocene formations. These results support the hypothesis that the plugs represent the original volcanic vents from which the plateau basalts were extruded.
Was the Good Friday Glacier on Axel Heiberg Island surging?
Authors: Müller Fritz
Published: April 2011

The lower part of the Good Friday Glacier on Axel Heiberg Island, N. W. T., started, sometime between 1952 and 1959, a period of markedly increased movement associated with a frontal advance of over 2 km, which showed clearly some of the features attributed to a glacier surge, while others were lacking. Such border cases merit special attention.
Evidence of surges on the Barnes Ice Cap, Baffin Island
Authors: Løken O. H.
Published: April 2011

The morphology of the Barnes Ice Cap is studied on the basis of detailed topographic maps. Two anomalous areas characterized by an apparent excess of mass at lower elevations and a similar deficit at higher altitudes are identified. Local surges affecting these two parts of the ice cap could have caused this mass distribution. The moraine patterns adjacent to the ice cap show that the ice margin in the two areas has recently advanced in distinct contrast to the general retreat in adjacent areas.
The ice-dam, powder-flow theory of glacier surges
Authors: Nielsen Lawrence E.
Published: April 2011

In this theory it is assumed that a stagnant ice block or dam develops in the lower regions of a glacier. Ice gradually builds up above the dam while the dam itself becomes thinner by ablation. Eventually the upper end of the stagnant ice block crumbles from the force of the ice above it, and much of the glacier is changed from a state of compression to one of tension. The breaking of the ice dam results in the glacier rapidly becoming broken into a mass of blocks or powdered ice. The apparent viscosity of the broken-up glacier is much less than that of bulk ice, so high velocities of flow are possible, and a phenomenon similar to a mud flow results. This theory explains why some glaciers repeatedly surge yet appear stagnant between surges. The broken-up appearance of surging glaciers and the delayed surging of tributaries are explained. Additional substantiating observations on several of these phenomena are presented.
Comparison of moraines formed by surging and normal glaciers
Authors: Rutter Nathaniel W.
Published: April 2011

A Neoglacial moraine of Bighorn Glacier, St. Elias Mountains, Yukon, probably formed by a surging glacier, and a Neoglacial normal moraine of nearby Grizzly Glacier were studied. Surficial deposits and erosional features were mapped, Fabric analyses were done in till at five sites in each moraine. Samples were subjected to laboratory lithologic and texture analyses.The Bighorn (surge) moraine is a thin, discontinuous, irregular mantle, mostly till, but including ice-contact stratified material. Lateral moraines show subdued ridges marking the upper limit of glaciation. Ground moraine of the Grizzly (normal) glacier is an irregular, continuous, thick mantle, mostly till and. ice-contact stratified material. Upper ice limits are marked by prominent ridges. Rocks of similar lithologies within the till are concentrated in bands parallel to glacier flow.Stones in till of the Grizzly moraine have strong preferred orientation roughly in the direction of glacier flow. In the Bighorn moraine, rocks in till are weakly oriented. Where orientation is apparent, it is not necessarily in the flow direction. For the size fraction finer than 2 mm, Bighorn till is coarser than Grizzly till although the bedrock terrain is similar.These differences are useful in distinguishing moraines of normal and surging glaciers.
A new Lower Devonian rock unit in the Canadian Arctic Islands
Authors: Ormiston Allen R.
Published: April 2011

A thin, shelf-type carbonate unit with an abundant shelly fauna of Lower Devonian age is developed in the vicinity of Drake Bay, northwestern Prince of Wales Island where it rests on a dolomitic western facies of the dominantly clastic Peel Sound Formation. These limestones and shales which contrast in thickness, lithofacies, and biofacies with coeval rocks exposed in the Stuart Bay area of Bathurst Island 190 miles (306 km) to the north, represent a new stratigraphic unit.The lithologic characteristics, stratigraphic relations, fauna, and age of the unit are documented, but no name is proposed because of the incompleteness of the exposure and because a more suitable type section is available.
Magnetic "field free" spaces for paleomagnetism, rock magnetism, and other studies
Authors: Roy J. L. , Robertson W. A. , Keeping C.
Published: April 2011

An array of five sets of 8-ft (244-cm) square coils for compensation of the earth's magnetic field at five locations is described. A fluxgate system is used to keep the residual field within 2 gammas during magnetic storms and 1 gamma in other instances. Constant fields (1 Oe down to a few gammas), for experiments in small magnetic fields, can be produced at four locations independently.
Ichthyodectes and Holcolepis from the Cretaceous of Lac des Bois, Northwest Territories, Canada
Authors: Waldman M.
Published: April 2011

A complete skull of Ichthyodectes ctenodon (Ichthyodectidae) and scattered remains of small individuals of the same genus together with Holcolepis (Elopidae), are recorded in association from Cretaceous sediments on the western shore of Lac des Bois, Northwest Territories. The strata are probably of Albian–Cenomanian age, this being based on the fish evidence. The occurrence of this association in the far north of Canada was previously unknown and provides fresh evidence of freedom of nektonic movement in the Cretaceous Mediterranean – North American seaways.
Paleointensity study of late Miocene igneous rocks from British Columbia, Canada
Authors: Symons D. T. A. , Schwarz E. J.
Published: April 2011

Sixty-nine specimens representing 49 late Miocene (10–15 m.y. ago) basaltic lava flows and 4 associated gabbroic intrusive plugs were studied in an attempt to estimate the paleointensity of the earth's magnetic field in south-central British Columbia. The paleointensity determination was based on the comparison of the decay of natural remanent magnetism intensity with that of an artificial thermoremanent magnetism (H = 0.35 Oe) in progressively higher alternating demagnetizing fields (peak: 800 Oe). Only 22 of the 69 specimens were considered to yield reliable paleointensity determinations which give an estimated average equatorial intensity for the late Miocene earth's field of 0.18 Oe ± 0.11. This result agrees reasonably well with those from contemporaneous rocks from North America, Japan, and Iceland. Several low determinations with consistent, normal, or reversed remanence directions suggest that the intensity of the non-dipole components of the late Miocene earth's field must have been very small in the sampled area.
Discussion of the progress report of the Federal–Provincial Committee on Huronian Stratigraphy
Authors: Church W. R. , Young G. M.
Published: April 2011

It is argued that the term "Huronian", which has been, and still is, widely used as a time-stratigraphic term, serves a useful purpose in correlating the early Proterozoic rocks of Ontario with those of the Lake Superior region. It should not be used, therefore, as a rock-stratigraphic name of only local significance, as has been suggested in the progress report of the Federal–Provincial Committee on Huronian Stratigraphy, but be retained as an informal 'systemic' name pending clarification of conflicting results of age relationships of early Proterozoic rocks of the Great Lakes region.A scheme of stratigraphic nomenclature is tentatively outlined for the early Proterozoic rocks of the Great Lakes region.
Comments on a Cretaceous coprolite from Alberta, Canada
Authors: Waldman M.
Published: April 2011

A coprolite (N.M.C. 13565) containing remains of a gar-pike, from the Upper Cretaceous, non-marine, Oldman Formation of Alberta is believed to be that of a crocodile, although it may be possibly derived from a terrestrial carnivorous reptile of necrophagic or piscivorous habit. X-ray diffraction studies show the specimen to be composed of apatite.
A new Lower Devonian rock unit in the Canadian Arctic Islands: Discussion
Authors: Miall Andrew D.
Published: April 2011

Vertebrate fossils from clastic rocks of the Peel Sound Formation on north-central Prince of Wales Island indicate that rocks as young as Emsian may be present, contrary to the statement of Ormiston (1969) that Siegenian to Emsian carbonate sediments on northwestern Prince of Wales are the youngest rocks present on the island. A revised cross-section through northern Prince of Wales shows Ormiston's carbonates as a facies variation of the Peel Sound Formation, which rests on the underlying Read Bay Formation with a generally gradational contact, not a regional unconformity.
Acid leaching of red beds and the relative stability of the red and black magnetic components
Authors: Park J. K.
Published: April 2011

A technique for leaching rock specimens with acid has been developed for the investigation of the magnetic properties of red sediments. The efficiency of the leaching depends strongly on the shape of the specimen, and cylindrical specimens with an axial hole were found to be the most suitable, both for the leaching process and for subsequent magnetic measurements. Applying the technique to Carboniferous red sandstones from the Maritime Provinces, two magnetic components were separated and identified with red and black constituents. The red magnetic component has higher blocking temperatures and coercivities than the black, and is more resistant to alternating field demagnetization. An earlier explanation of the magnetization of these red beds requires some modification.
La structure de Charlevoix comparée à d'autres impacts météoritiques
Authors: Rondot Jehan
Published: April 2011

Most of the circular structures considered as meteorite impacts have a central uplift and a well-developed annular depression. A graph of vertical stratigraphic displacement of the central uplift and depression as a function of depression diameter indicates linear relations. However, vertical displacement is not exactly proportional to the diameter. The vertical displacement of the depression is about 1/40 the diameter for smaller structures and about 1/30 the diameter for larger structures.
Sulfur isotope effects in volcanic gas mixtures
Authors: Grinenko V. A. , Thode H. G.
Published: April 2011

Sulfur isotope effects in the exchange systems (1) [Formula: see text] and (2) [Formula: see text] have been studied at various temperatures. It has been shown that in the presence of water vapor sulfur isotope exchange proceeds at an appreciable rate in (1) above 150 °C and in (2) above 300 °C.The isotopic exchange constant for (1) approaches unity in the temperature range from 200 to 400 °C and the exchange constants for (2) at 400 °C and 450 °C equal 1.0095 and 1.0090 respectively favoring 34S in the SO2.The kinetic isotope effect in the chemical reduction of SO2 to S0 in consequence of its interaction with H2S has been determined at 25 °C, 200 °C, and 280 °C. At these temperatures the 32SO2 molecules react 1.6% faster than the 34SO2 molecules.It is concluded that the spread in isotopic composition of various forms of sulfur in volcanic gases is caused not only by isotope exchange reactions between oxidized and reduced forms of sulfur but also by kinetic isotope effects in unidirectional reactions which result from major temperature changes at the outflow.
Geology and Geochronology of the Hellroaring Creek Stock, British Columbia
Authors: Ryan B. D. , Blenkinsop J.
Published: April 2011

Hellroaring Creek Stock intrudes rocks of the Precambrian Purcell Supergroup which crop out in southeastern British Columbia. Previous K–Ar measurements (Lowdon 1961) indicated a minimum age of 700 m.y. for this stock. Present Rb–Sr isotope measurements indicate an approximate age of 1260 m.y. Cleavage in the contact aureole of the stock indicates a structural event prior to intrusion.
Phase Equilibria in the System NaAlSi3O8–NaAlSiO4–H2O with Special Emphasis on the Stability of Analcite
Authors: Kim Ki-Tae , Burley B. J.
Published: April 2011

Phase equilibria were determined in the P–T range of 0.5–10 Kb and 150–900 °C in the system NaAlSi3O8 – NaAlSiO4 – H2O. Two isobaric (2 Kb and 5.15 Kb) T–X phase diagrams (projected to a dry base) were completely determined and show that the stability field of analcite solid solutions has a large distorted pentagonal shape. The phase relations for the transition: nepheline hydrate I [Formula: see text] nepheline + H2O on the composition join NaAlSiO4 – H2O are not binary. It was found that there exists a narrow zone for the transition. The true P–T curve was found and determined in terms of a ternary univariant reaction: nepheline hydrate I + analcite [Formula: see text] nepheline + H2O. In the system NaAlSi3O8 – SiO2 – H2O, albite contains about 5 wt % silica in solid solution at 5.15 Kb and 670 °C.The equilibrium compositions of various univariant phases were determined essentially on the basis of the T–X phase diagrams. Another univariant reaction (zeolite species P = analcite + nepheline – hydrate I + H2O) was found at 2 Kb/215 °C and 5.15 Kb/235 °C and determined on a P–T projection. Three singular points were determined; two of them are located at 0.8 Kb/390 °C and 9.4 Kb/475 °C respectively on a univariant P–T curve for the reaction nepheline hydrate I + analcite = nepheline + H2O; the other one is located at 6 Kb/655 °C on a univariant P–T curve along which nepheline, analcite, liquid, and vapor coexist. The petrogenetic implication of analcite is discussed fully.
Rb–Sr Study of Shock-metamorphosed Inclusions from the Onaping Formation, Sudbury, Ontario
Authors: Fullagar Paul D. , Bottino Michael L. , French Bevan M.
Published: April 2011

Sixteen inclusions from the Onaping Formation, a possible meteorite impact breccia at Sudbury, Ontario, were analyzed for Rb, Sr, and Sr isotopic composition. Inclusions ranged from weakly shocked granitic rocks to heterogeneous glassy inclusions (impact melt?). Strongly shocked and glassy inclusions yield separate isochrons of 1430 ± 65 m.y. and 1480 ± 55 m.y., respectively (λ 87Rb = 1.39 × 10−11 y−1). Twenty-eight samples, including data for Onaping Formation samples from the literature, have an isochron age of 1515 ± 65 m.y. Isochron initial 87Sr/86Sr ratios range from 0.714 to 0.717, The Onaping samples thus appear anomalously younger than the 1700 m.y. ages reported for the geologically younger Nickel Irruptive and Whitewater sediments. If the highly shocked granitic inclusions and glasses in the Onaping Formation are relatively susceptible to radiogenic Sr loss during subsequent thermal events, the data are compatible with an impact origin for the Sudbury structure. The whole-rock ages, combined with reported mineral ages, suggest a metamorphic event in the Sudbury area 1400–1500 m.y. ago.
Paleomagnetism of the Franklin Diabases
Authors: Fahrig W. F. , Irving E. , Jackson G. D.
Published: April 2011

Diabase intrusions, which have a probable mean age of 675 m.y., occur in a giant arc across the northern part of the Canadian Shield. They have a paleomagnetic pole position of 167° E, 8° N (α95 = 5°), and at least one reversal. The paleomagnetic results indicate that the northern Canadian Shield was near the equator at the time of intrusion, and this is in agreement with evidence of warm conditions of deposition found in erosional remnants of related late Proterozoic sediments. Some of the diabase, near the shores of Davis Strait, may have been partially remagnetized during the opening of Baffin Bay in the early Tertiary.
Phase Equilibria in the System NaAlSi3O8 – NaAlSiO4 – H2O Up to 15 Kb. A Theoretical Discussion
Authors: Kim Ki-Tae , Burley B. J.
Published: April 2011

Phase relations in the system NaAlSi3O8 – NaAlSiO4 – H2O up to ~15 Kb have been discussed from a theoretical standpoint. The discussion is based on the equilibrium compositions of invariant phases. Two new invariant points, I5 and I6, have been predicted: I5 at ~13 Kb/~500 °C where five phases, jadeite, nepheline hydrate I, analcite, nepheline, and water vapor coexist, and 16 at ~0.5 Kb/~375 °C where albite, nepheline, analcite, nepheline hydrate I, and water vapor coexist. The phase relations around four previously known invariant points including a singular point S4 have been examined and partly modified.The maximum P–T stability field of analcite has been deduced. The stability field of subsolidus analcite is extremely large, whereas that of liquidus analcite is very much limited. The maximum stability field of liquidus analcite is a small triangular area defined by three invariant points, I1 (5.15 Kb/657 °C), I2, (11 Kb/650 °C), and I4 (12.5 Kb/575 °C). It is concluded that most liquidus analcite (primary analcite) is attributed to the crystallization from H2O-undersaturated melt.
A Review of Geophysical Studies in the Canadian Cordillera
Authors: Berry M. J. , Jacoby W. R. , Niblett E. R. , Stacey R. A.
Published: April 2011

Geophysical studies of the crust and upper mantle have been conducted in the Canadian Cordillera for over two decades, but only recently have sufficient data been collected to permit a synthesis and a correlation with the major geological units. The studies have included gravity, heat flow, and magnetotelluric observations, geomagnetic depth sounding, and high level aeromagnetics as well as both small and large scale refraction and reflection seismic surveys.It now appears that major crustal units may be recognized geophysically:(i) Seismic and gravity data suggest that the Plains and Rocky Mountains are underlain by two units of the North American craton with a crustal section 45–50 km thick. The northern unit appears to terminate at the Rocky Mountain Trench while the southern unit may extend to the Omineca Geanticline.(ii) The combined geological and geophysical data suggest that the Rocky Mountain Trench and possibly the Kootenay Arc near the 49th parallel mark the edge of the Precambrian continental margin and that the western Cordillera was formed by a complex succession of plate interactions with repeated reactivation of block boundaries.(iii) A combination of magnetic and heat flow data suggest that the region between the Rocky Mountain Trench and the Fraser Lineament is part of the Cordilleran Thermal Anomaly Zone recognized by Blackwell in the United States.(iv) Seismic data in Central British Columbia suggest that the Pinchi Fault system is a boundary between two crustal blocks.(v) The crustal thickness of the Coast Geanticline appears to increase gradually to the west to approximately 40 km and, at least in southern British Columbia, does not have a root zone below the mountains.(vi) The crustal section beneath Vancouver Island is abnormally thick and there is some paleomagnetic data which suggest that the Island may not have been formed in its present position, contiguous to the Cordillera. The crustal section for the northern part of the Insular Trough is significantly thinner.(vii) The active spreading of the Juan de Fuca Rise – Explorer Trench is now well documented. The geophysical data suggest active subduction of the Juan de Fuca plate beneath Oregon, Washing-ton, and southern Vancouver Island. However, further north there is no evidence for subduction.
Expressions for Calculating the Solubilities of Metal Sulfides in Hydrothermal Solutions
Authors: Nriagu Jerome O.
Published: April 2011

Expressions describing the solubilities of metal sulfides in multicomponent hydrothermal solutions have been derived, taking into account the hydrolysis of the sulfide ion and the simultaneous complexing of the metal cation by one or more ligands. Complexing in both sulfur-rich and sulfur-deficient hydrothermal systems has been considered. Examples presented show that complex formation per se may not lead to the relative solubility of the base metal sulfides which can explain the zonal sequence identifiable in many hydrothermal deposits.
Size of Items of Primary Information for Research in Physical Geochemistry
Authors: Smith F. G.
Published: April 2011

Regression analysis of page-length vs. year of publication of primary items on a specific subject within the field of physical geochemistry shows a significant decelerating decrease. Extrapolation into the future indicates a page-length near unity by the end of this century.
Interpretation of the Gravity Anomaly at Darnley Bay, N.W.T.
Authors: Stacey R. A.
Published: April 2011

The almost circular gravity anomaly which lies at the head of Darnley Bay on the Arctic coast 400 km east of the Mackenzie Delta, has a radius of 50 km with Bouguer values rising 130 mgal above the background field. It is concluded that the anomaly is due to a basic or ultrabasic body in the form of a truncated cone (which may narrow towards the surface or downwards), lying at a comparatively shallow depth within the Proterozoic sediments. Having obtained a feasible configuration for the body, the influence it may have had on the deposition of later Proterozoic and early Paleozoic sediments is discussed in speculative terms.
A Geographical Relation Between Geomagnetic Variation Anomalies and Tectonics
Authors: Law L. K. , Riddihough R. P.
Published: April 2011

A world review of the available geomagnetic variation data, with a standardized presentation of results from North America and Europe, shows that there is a geographical relation between inland geomagnetic variation anomalies and tectonic features. Particularly evident in North America is a correlation between anomalies and the edge of the stable craton. Other anomalies are situated along fold belts (eastern Canadian Arctic) and rift-fault zones (Rhine Graben, Iceland). With the exception of that in Japan, all reported anomalies are shown to occur within these three tectonic categories. In terms of plate theory, these categories and the island arc system related to Japan are characteristic of past or present plate boundary zones. A close association between plate margins and geomagnetic variation anomalies is thus implied.
Body Force Equivalents as Sources of Anelastic Processes
Authors: Nyland Edo
Published: April 2011

Once a failure criterion and a rule for conversion of mechanical into thermal energy are established, linear elastic materials can be made to behave, theoretically at least, in a highly anelastic fashion. Such hypothetical materials could be of particular value in the analysis of slow deformation of the earth.
Ages of Lamprophyre Dikes and of the Mongowin Pluton, North Shore of Lake Huron, Ontario, Canada
Authors: Schmus W. R. Van
Published: April 2011

Rb–Sr analyses have been carried out on samples of lamprophyre dikes and of granophyric phases of the Mongowin Pluton, two units that intrude Huronian metasediments in the Espanola–Massey area. Data on whole rocks and separated biotites from the lamprophyres yield an isochron age of 1415 ± 40 m.y., which is interpreted as the age of intrusion of the lamprophyre dikes. Whole rock granophyric samples from the Mongowin Pluton do not define a good isochron, but an "age" of 1770 ± 75 m.y. may be inferred from the data; the possibility exists, however, that the true age may be younger or older. The lamprophyre dikes and the Mongowin Pluton are apparently unrelated to each other; furthermore, neither unit appears to be the same age as the 1510 ± 50 m.y. old Croker Island Complex. Thus, there is little evidence to suggest that there was a major intrusive 'event' approximately 1500 m.y. ago in the north shore area; instead, it appears that diverse igneous and metamorphic activity occurred at several scattered times during the interval 1200 m.y. to 1800 m.y. ago.
U–Pb Ages for Sphene from Early Precambrian Igneous Rocks in Northeastern Minnesota – Northwestern Ontario
Authors: Catanzaro E. J. , Hanson G. N.
Published: April 2011

Five sphene concentrates from early Precambrian igneous granitic rocks in northeastern Minnesota and northwestern Ontario give 207Pb–206Pb ages of 2680–2750 m.y., which are in good agreement with discordant U–Pb ages for zircon and whole-rock Rb–Sr ages (λβ = 1.39 × 10−11y−1) from these rocks. Three of the sphene concentrates give concordant ages, two discordant.Although the rocks have undergone at least one low-grade metamorphism, which has affected some of the K–Ar and Rb–Sr mineral ages from the region, the 207pb–206pb ages for sphene do not appear to have been affected.An electroplating technique was employed for recovering the lead from the sphenes after decomposition in perchloric and hydrofluoric acid.
Generation of Synthetic Seismograms Using Linear Systems Theory
Authors: Jensen O. G. , Ellis R. M.
Published: April 2011

The linear systems theory for elastic wave propagation in a multilayered crust has been extended to time domain solutions. Attenuation is specifically included. This direct time domain approach allows the computation of synthetic seismograms for P or SV waveforms incident at an arbitrary angle at the base of the crustal section. To demonstrate the utility of the technique, seismograms are computed for various conditions and comparisons made with teleseismic events recorded in central Alberta.
Fission Track Ages of some Indian Muscovites
Authors: Gupta M. L. , Nagpaul K. K. , Mehta P. P.
Published: April 2011

Seven samples of muscovite from three main mica-producing regions of India, i.e. Rajasthan, Bihar, and Andhra Pradesh, have been dated by the fission track technique. The geological annealing of fossil radiation damage has been assessed by comparative study of induced and fossil track lengths. The uranium concentration has been measured in tight cleavages so as to avoid errors due to contamination. The measured ages give an indication of the main orogenic metamorphic cycles in the respective regions.
Oxygen Isotope Ratios of Submarine Diorites and their Constituent Minerals
Authors: Muehlenbachs K. , Clayton R. N.
Published: April 2011

The δ18O values of submarine diorites recovered from the Mid-Atlantic Ridge near 45° N range from 5.2 to 6.9 ‰. Coexisting minerals are not in isotopic equilibrium. The disequilibrium resulted from the interaction of the diorites with fluids of unknown origin at high temperatures.
Behavior of an Archean Granitic Batholith
Authors: Clifford Paul M.
Published: April 2011

The Bamaji–Blackstone granite has 'invaded' volcanic rocks of the Lake St. Joseph area, northwestern Ontario. The resulting deformation, close to the granite, is substantially pure shear in three dimensions. This is indicated by flattened but not noticeably unidirectionally extended pillows, and by chocolate-tablet boudinage. Both features imply extension in all directions parallel to the granite margin and marked compression on horizontal axes normal to the granite margin. The flattening (compression) is also suggested by buckled granitic dikes enclosed in the flattened pillows. The discrepancy between the strains in pillows and dikes is explained as due to the late arrival of the dikes. Flattening persists away from the granite, but is increasingly accompanied by marked extension on sub-vertical axes, a deformation pattern akin to die drawing.The flattening mode is ascribed largely to the diapiric uprise of the granite, much modified by inflation of the granite due to the arrival of granitic magma late in the 'invasion' process. The granitic dikes presumably represent some magma that escaped.
Flow through the Charlie-Gibbs Fracture Zone, Mid-Atlantic Ridge
Authors: Garner D. M.
Published: April 2011

The flow of deep water across the axis of the Mid-Atlantic Ridge through the Charlie–Gibbs Fracture Zone near 52.5 °N was monitored for 7 days during June, 1970 with current meters moored 50 m and 650 m above the bottom in each of the two zonal channels of the fracture. Flow was west-going through the fracture. The mean rate of flow was about 3 cm/s with an oscillatory flow superimposed of semi-diurnal tidal period.
Tectonics and Depositional History of the Continental Margin Off Vancouver Island, British Columbia
Authors: Tiffin D. L. , Cameron B. E. B. , Murray J. W.
Published: April 2011

Sampling and seismic profiling in the Tofino Basin west of Vancouver Island show there is a thick sequence of Tertiary rocks ranging in age from late Eocene to Pliocene. The rocks are mainly mudstones containing abundant foraminifera indicating a bathyal depositional environment throughout most of the Tertiary. Subsequent uplift has exposed the deep water sediments on the shelf over much of the area. Eocene-Oligocene sediments occur in a belt along the inner shelf, while Miocene and Pliocene rocks lie seaward of this. Pliocene rocks form a regressive sequence overlapping the older Tertiary, with the greatest thickness in the south.At least two major periods of deformation resulted in faulting, folding, and diapirism on the continental shelf. Deformational patterns show a marked change from north to south. North of Brooks Peninsula sediments are undeformed by folding but are truncated by faulting along the steep continental slope. The Kyuquot Uplift south of Brooks Peninsula exposes Eocene-Oligocene sediments across the shelf. Farther south Mio-Pliocene sediments unconformably overlie the uplift. Folding increases southward culminating in an area of diapirism off Nootka Sound. Elongate diapirs trend parallel or subparallel to the coastline.Tectonic features on the shelf and slope appear to be related to present and earlier configurations of nearby offshore spreading centers, plates, and transform faults. Crustal plate movements may have been responsible for the observed shelf and slope deformations.
Multiple Deformation of Crystalline Rocks in the Tazin Group, Eldorado Fay Mine, NW Saskatchewan
Authors: Krupička J. , Sassano G. P.
Published: April 2011

The crystalline rocks of the uranium-bearing Precambrian Tazin Group on the north shore of Lake Athabasca in Saskatchewan have long been known to contain a high proportion of cataclastic rocks. A detailed microscopic textural study of the Tazin rocks from the Eldorado Fay Mine, Beaverlodge, shows that: (a) all units of the Tazin Group have been affected by strong postcrystalline (partly syncrystalline) deformation; (b) in many places the deformation reached the highest degree of crushing encountered in sheared rocks; (c) deformation occurred in several distinct phases separated by considerable time intervals and at successively higher structural levels; and (d) the rocks are thus polydeformational.The deformation was so strong that many crystalline rocks have developed the outward appearance of argillites and tuffs.
Digital Filtering of Deep Crustal Seismic Reflections
Authors: Clowes R. M. , Kanasewich E. R.
Published: April 2011

Seismic reflections at near-vertical incidence from within the lower crust were recorded along a 90 km continuous profile in southern Alberta. The digitized seismograms were filtered as a means of improving signal-to-noise ratios. Zero-phase bandpass filtering improves the quality of the records but also introduces a disadvantage; the narrow pass bands cause the filtered seismograms to become more oscillatory and exclusion of the higher frequencies destroys some of the record character which is useful in phase correlation. Velocity filtering is shown to be a more effective means of delineating individual reflection events, particularly if their apparent velocities vary widely. A record section compiled from such filtered data indicates a considerable number of reflecting horizons at various depths in the lower crust. When the reflections are migrated and a "wiggle" structure section compiled, the complexity of the lower crust in southern Alberta is revealed. Vertical relief reaches as much as 9 km over a horizontal distance of 40 km and lateral changes in the layered system can be noted.
A System for Measuring the Electric Field at the Ocean Floor
Authors: Srivastava S. P.
Published: April 2011

A self-contained recording system to measure the electric currents at the bottom of the ocean is described. The system was used to measure these currents on the Scotian Shelf south of Halifax, Canada. Comparison of the electric field recorded on the shelf with the magnetic field recorded at a shore based station show good correlation.
A Principal Reference Section Proposed for the Nepean Formation of Probable Tremadodan Age Near Ottawa, Ontario
Authors: Greggs Robert G. , Bond Ivor J.
Published: April 2011

A principal reference section for the Nepean Formation in Eastern Ontario is proposed. This section is located west of Ottawa, Ontario in Nepean Township and south of the original Nepean quarries which supplied much of the stone used in the construction of the Parliament Buildings. These quarries are now filled in and little outcrop is visible.The Nepean sandstones are considered to be an offshore deposit of a shallow sea. The sandstone beds low in the section show foreset bedding, oscillation ripple marked surfaces, desiccation cracks, and occasional burrowing. Bioturbation is a dominant feature in the upper beds of the sequence.Throughout southeastern Ontario, the Nepean Formation unconformabîy overlies the Precambriam, and is overlain with a sharp, possibly disconformable contact, by the March Formation of Tremadocian age. The Nepean Formation is considered to be younger than the Potsdam Formation of Potsdam County, New York State, and to be Lower Tremadocian.
The Mid-Atlantic Ridge Near 45 °N. XX. The Gravity Field
Authors: Woodside J. M.
Published: April 2011

Detailed maps of free-air, Bouguer, and residual gravity anomalies for a survey area 250 km wide across the Mid-Atlantic Ridge between 45° and 46 °N have been compiled. The Bouguer anomaly was terrain-corrected to a radius of 40 km. The residual anomaly was computed from the terrain-corrected Bouguer anomaly using an empirical linear relationship between the Bouguer anomaly and the bathymetry to predict a 'regional' Bouguer anomaly from the depth data. North–south and east–west trends in the gravity data are enhanced in the residual anomaly; and it is suggested that at least one short east–west transform fault may offset the ridge in a right-lateral sense. The offset is presumably a response to a change in sea-floor spreading direction from west–northwest/east–southeast to west/east about 10 m.y. ago. A change in spreading rate may have occurred at the same time. A difference in accretion rate on either side of the ridge axis is indicated by asymmetry in the gravity data and by differences in the topographic compensation across the axis. Variations in the relationship of terrain-corrected Bouguer anomaly to bathymetry within the survey area suggest that a density deficiency or buoyant forces in the upper mantle are responsible for the overall elevation of the crestal mountain region but that the topography of the high-fractured plateau may be partially compensated by undulations of the crust–mantle interface.
Pleistocene Ringed Seal Skeleton from Champlain Sea Deposits Near Hull, Quebec–A Reidentification
Authors: Harington C. R. , Sergeant D. E.
Published: April 2011

A seal skeleton from Champlain Sea deposits near Hull, Quebec, formerly identified as probably belonging to a young harp or harbor seal, actually represents a seven year old ringed seal. The skeleton was deposited in situ, probably during an early cold phase of the Champlain Sea about 12 000–11 000 yr B.P. The specimen suggests that fast ice existed near the western margin of the Champlain Sea during winter and spring.
Glauconite in Surficial Sediments as an Indicator of Underlying Cretaceous/Tertiary Bedrock on the Northeast Newfoundland Continental Shelf
Authors: Slatt Roger M. , Hodge Robert A. L. , Uzuakpunwa A. B.
Published: April 2011

Glauconite in surficial sediment from part of the northeast Newfoundland continental shelf is similar in internal structure, external morphology, and abundance to glauconite in a probable Cretaceous or Tertiary subarkose dredged from the same area. This suggests: (1) the glauconite in surficial sediment is derived from the subarkose and/or possibly other glauconite-bearing rocks, (2) the subarkose is one lithology underlying the outer northeast Newfoundland shelf, and (3) the distribution of glauconite in surficial sediments may be used to 'map' underlying bedrock on the northeast Newfoundland shelf.
A Primitive Therian Mammal from the Upper Cretaceous of Alberta
Authors: Fox Richard C.
Published: April 2011

The discovery of tribosphenic molars of primitive construction in the Upper Milk River Formation (early Campanian), Alberta, documents the occurrence of a relict middle Late Cretaceous mammalian species that shows closest dental resemblance to Lower Cretaceous therians of metatherian–eutherian grade now classified as Theria, incertae sedis. The molar crowns of This new species have a wide stylar shelf, small, low protocone, distal trigonid crest, and lack conules and a shelf-like preparaconule crista mesial to the paracone; these and other coronal features indicate a more primitive level of molar evolution than known for Cretaceous Metatheria or Eutheria. Although too late in time to be ancestral to Cretaceous higher Theria, the new Milk River species may clarify aspects of their origin.
A Lower Paleozoic Rheo-Ignimbrite from White Bay, Newfoundland
Authors: Lock Brian E.
Published: April 2011

The Otter Cove and Ansteys Brook Members of the Natlins Cove Formation of western White Bay, Newfoundland are described and redefined. These members include bedded and chaotic tuffs, ignimbrites and pyro-turbidites, and a lava-like lithology shown to be a rheoignimbrite. The paleogeography and volcanic history of the area are reconstructed, and the rheo-ignimbrite is described and discussed. Comparisons are made with other examples.
Herpetofauna of the Calf Creek Local Fauna (Lower Oligocene: Cypress Hills Formation) of Saskatchewan
Authors: Holman J. Alan
Published: April 2011

A Lower Oligocene deposit, the Calf Creek local fauna of the Cypress Hills Formation, near Eastend, Saskatchewan, yielded the remains of one salamander, three anurans, three turtles, a crocodilian, six lizards, and three snakes. All of the 13 herpetological families identified are extant. The four amphibian genera identified are extant, but only two of nine reptilian genera identified are living today. One genus and species and one species of iguanid lizard, one species of xantusiid lizard, and one species of small boid snake are described as new. The Calf Creek local fauna herpetofauna indicates a subtropical or tropical climate. The herpetofauna of the Calf Creek local fauna shows several differences from the herpetofauna of the Middle Eocene Tabernacle Butte local fauna of the Bridger Formation of Wyoming.