bluuebunny/crossref_metadata_2025 huggingface dataset:
An analysis of size frequency distribution of oil and gas reserves of Western Canada
Authors: McCrossan R. G.
Published: April 2011

Both the oil and gas reserves of Western Canada are log-normally distributed. If the total reserves are separated into groups made up of single types of occurrence, these all display log-normal distributions as well. The parameters of the distributions vary considerably for different groups of genetically related accumulations. Many of the distributions also appear to be heterogeneous, showing distinct bimodality. Several hypotheses can be offered to explain this. For instance, the reserves of the group of smaller sized pools may be under-estimated for lack of sufficient information; secondly, geologically unlike types of pools may be grouped together. If the former is the case, an estimate can be made of the additional oil and gas in aggregate that may be undeveloped in the smaller under-estimated pools. The degree of bimodality may also indicate the maturity of an exploration play. Other possibilities are also considered. The distribution curves for the total reserves show only a generalized picture and obscure the characteristics of the individual distributions of the several types of oil or gas accumulations.
Observations on an alpine mudflow, Steele Creek, Yukon
Authors: Broscoe A. J. , Thomson S.
Published: April 2011

Alpine mudflows occurred on the ridges above Steele Creek, St. Elias Range, Yukon, on 11 July 1967, during a rainfall of 2.19 inches in 36 hours. One flow was observed in an area of flat-topped, steep-sided morainal terraces on the lower part of the north valley wall. This mudflow emerged in pulses from a notch at the upper margin of the terrace surface, and formed fronts 6 to 8 ft high. The arcuate fronts broke either to the east or west and the mud flowed across the fan, and through erosional notches to the valley floor. A detailed map and profiles show the topography and distribution of materials.The stream deposited coarse bed load on the alluvial fan on the upper terrace, then cascaded down the notch. Undercutting of the notch caused periodic collapse of the morainal material, which formed temporary dams. Water and finer bed load were impounded and the dam saturated but not overtopped. Saturated material emerged from the notch as viscous, rock-charged mud.Particles in the mudflow range in size from colloids to boulders 13 ft across. Pebbles from a mudflow sample included 70% locally derived lava and 18% granite from the moraine. Material finer than 2 microns was predominantly montmorillonite. Rain and runoff washed fine material from mudflow deposits, leaving a lag deposit similar to alluvial gravel.Botanical evidence indicates that mudflows occur at intervals of decades. The collapse of material from the sides of the steep-walled, high-gradient notch, cut into easily erodable till, controlled the pulsating nature of the observed mudflow.
An aeromagnetic study of the Moak Lake – Setting Lake structure in northern Manitoba
Authors: Kornik Leslie J.
Published: April 2011

An integrated aeromagnetic-geologic interpretation of the Moak Lake – Setting Lake structure, a distinctive magnetic feature which contains the Manitoba nickel belt, is presented. This structure is separated, on the basis of aeromagnetic and geologic data, into eastern and western areas. A main fault zone, which is mapped in part and is also an aeromagnetic lineament, separates the two areas. It is deduced that the western area of the Moak Lake – Setting Lake structure was involved in the Hudsonian orogeny only. The eastern area is interpreted to have been initially involved in the Kenoran (?) orogeny, which produced the characteristic charnockite and pyroxene granulite rocks, and was then reinvolved in the dynamic effects of the Hudsonian orogeny. A chronologic sequence of the major events in the area is presented.
High-pressure experimental studies on the origin of anorthosite
Authors: Green Trevor H.
Published: April 2011

Experimental crystallization of anhydrous synthetic quartz diorite (≈andesite), gabbroic anorthosite, and high-alumina basalt has been conducted in their respective partial melting fields at high pressure. The quartz diorite composition shows a large field of crystallization of plagioclase from 0–13.5 kb, together with subordinate amounts of orthopyroxene and clinopyroxene and minor opaque minerals. In the gabbroic anorthosite, plagioclase is the main phase crystallizing from 0–22.5 kb, but at higher pressure it is replaced by aluminous clinopyroxene. Aluminous clinopyroxene is the main phase crystallizing from the high-alumina basalt from 9–18 kb and is joined by plagioclase at lower temperatures. At higher pressure it is joined by garnet. The albite content of the liquidus and near-liquidus plagioclase increases markedly with increasing pressure in each of the three compositions.The results for the high-alumina basalt and gabbroic anorthosite compositions preclude any major trends towards alumina enrichment and derivation of anorthositic plutons at crustal or upper mantle depths under anhydrous conditions. However, the results for the quartz diorite suggest that anorthositic complexes may form as a crystalline residuum from the partial melting of a lower crust of overall andesitic composition or from fractional crystallization of an andesitic magma. In either case a large separation of plagioclase crystals occurs (andesine – acid labradorite composition at lower crustal pressures), together with subordinate pyroxenes and ore minerals. Under appropriate temperature conditions separation of crystals and liquid by a filter-pressing mechanism during deformation may result in the genesis of igneous complexes containing rock types ranging in composition from gabbro through gabbroic anorthosite to anorthosite, together with associated acid rocks. The acid rocks need not necessarily remain spatially associated with the refractory gabbroic anorthosite and anorthosite. Where these processes have operated in the crust, anorthositic rocks may be left as the main component of the lower crust, while the low melting acidic fraction has intruded to higher levels.
Proterozoic paleocurrents and depositional history of the East Arm fold belt, Great Slave Lake, Northwest Territories
Authors: Hoffman Paul
Published: April 2011

Nearly 40 000 ft (~12 190 m) of unmetamorphosed Aphebian (and possibly lowermost Helikian) sedimentary and volcanic rocks are exposed in the East Arm of Great Slave Lake. This sequence is an erosional remnant of an Appalachian-type geosynclinal complex with a NNW depositional strike. Integrated paleocurrent, stratigraphic, and sedimentological analysis reveals three stages in the depositional history of the complex: (1) a double transgressive, pre-orogenic miogeosyncline, which received sediment from a distant cratonic source to the ENE and which becomes thicker and more eugeosynclinal to the WSW; (2) a regressive, syn-orogenic exogeosyncline (clastic wedge), which received sediment from rapidly uplifted tectonic lands to the WSW; and (3) a continental, post-orogenic taphrogeosyncline (down-faulted intermontaine trough), which received sediment locally from block-fault scarps within the East Arm area.Facies predictions based on this model provide criteria for establishing stratigraphic correlation and contiguity between the East Arm and other Aphebian sequences in the northwestern Canadian Shield. The prevailing depositional strike is roughly perpendicular to the tectonic strike of the East Arm Fold Belt, and it should not therefore be assumed that depositional strike parallels tectonic strike in other belts. The Bear Province may have been the site of the orogenically active axial zone of the geosyncline, but that part of the Churchill Province near the East Arm remained passive until the final post-orogenic stage of sedimentation and may therefore be of epeirogenic origin.
Striations, giant grooves, and superposed drag folds, Interlake area, Manitoba
Authors: Wardlaw N. C. , Stauffer M. R. , Hoque M.
Published: April 2011

Cross-cutting relationships of glacial striations on carbonate bedrock, in the Steep Rock – Gypsumville district, Manitoba, suggest movement of glacier ice generally to the southeast followed by movement generally to the west or southwest.These two major sets of striations have orientations similar to those of linear topographic depressions and ridges of low relief, which are conspicuous on airphotos. Although in glacial drift, the surface grooves overlie grooves in bedrock which apparently are the result of glacial erosion. The topographic grooves and intervening ridges resemble features described from other parts of the Lake Agassiz Plain, and have been assigned a variety of origins. The surface grooves cannot be correlated in trend to joints in bedrock.Two major sets of superposed folds are exposed in gypsum at Gypsumville and in carbonates at Spearhill. The similarities between the folds, in the gypsum and the carbonates, suggest that they have a common origin. The trends of the axial planes of the two sets of folds are approximately perpendicular to the two major trends of glacial striations and surface grooves. Glacial drag is the most probable cause of folding in both gypsum and limestone.
A new specimen of Stenonychosaurus from the Oldman Formation (Cretaceous) of Alberta
Authors: Russell Dale A.
Published: April 2011

A fragmentary skeleton of Stenonychosaurus inequalis indicates that this small theropod dinosaur is very closely related to Saurornithoides mongoliensis from the Cretaceous of central Asia. Both forms possessed relatively well developed cerebral hemispheres and large eyes, and were probably fleet bipeds with supple raptorial forelimbs. Their extreme rarity as fossils is attributed to their preference for environments not usually preserved in the stratigraphic record.
Paleomagnetic evidence for the extent of Mackenzie igneous events
Authors: Fahrig W. F. , Jones D. L.
Published: April 2011

North-northwesterly striking Mackenzie diabase dikes of middle-Proterozoic (Helikian) age are profuse in the western part of the Canadian Shield. Published paleomagnetic data on dikes of this trend in Mackenzie District, on the Muskox Intrusion, the Coppermine River volcanic rocks, and the Sudbury dikes suggest that they are all products of closely related igneous events. This paper presents paleomagnetic data that suggest that the intrusion of extensive diabase sheets in the East Arm of Great Slave Lake, and of dikes as far to the northeast as Melville Peninsula and as far to the southeast as Manitoba, were also parts of these events. The mean paleomagnetic pole position for the Mackenzie dikes and for related intrusive and extrusive rocks is [Formula: see text], 171 °W with [Formula: see text]. Radioactive age determinations, some of which are unpublished, indicate an age of about 1200 m.y. for the formation of these rocks. It is suggested that for convenience all of these apparently related intrusive and extrusive igneous episodes be referred to as Mackenzie igneous events.
Evidence for post-ore metadiabase at the Horne Mine, Noranda, Quebec
Authors: Darling Richard , Suffel G. G.
Published: April 2011

Contacts between metadiabase dikes and massive sulfide ore in the Horne Mine exhibit patterns of dike chill and sulfide alteration that show the dikes to be younger than the sulfides. The sulfides are thus older than all intrusive igneous rocks in the mine area and an Archean volcanogenic origin for these ores seems likely.
Current observations on three surges in Glacier Bay, Alaska, 1965–1968
Authors: Field William O.
Published: April 2011

Nine glaciers in Glacier Bay, in southeastern Alaska, and three others within a radius of 60 km have been known to surge in the last 60 years. Of these, seven have surged during the 1960's. The surges of three of them, the Tyeen, Rendu, and Carroll, are discussed in this paper. Each glacier has surged one or more times previously. The course of each surge has been documented by photography but there has been no study of the regimes of these glaciers. The distribution in time and space of these and other surges in the Glacier Bay area are discussed and it is suggested that there may be external factors which cause more surges during some periods than others. These relationships need to be correlated and analyzed. A program of future observations is suggested.
Structural development of the Paleozoic rocks of western Gaspé, Quebec
Authors: Sikander A. H. , Fyson W. K.
Published: April 2011

Cambro-Ordovician greenschists and phyllites in the Shickshock Mountain area are characterized by a foliation S1 almost completely parallel to layering S0, and a mineral lineation apparently axial to obscure tight folds F1. Absence of these structures from Lower to Middle Ordovician argillites immediately to the north of the Shickshocks suggests that F1 folding and metamorphism occurred earlier than at least part of the Early Ordovician Epoch.The dominant folds F2, which affect all Lower and Middle Paleozoic rocks, trend northeast and include the Gaspé synclinorium with a Siluro-Devonian axial zone. F2 are upright to inclined, and an axial-surface fracture cleavage S2 forms a major fan divergent upward across the synclinorium. F2 hinges are generally low plunging; but some are curved as much as 90°, perhaps because of variable dip-slip on S2.Discontinuous folds F3 exposed only in Ordovician rocks on the north coast, have steep axial surfaces striking eastward oblique to northeast-trending S2 cleavage. Small kinks, F4, virtually restricted to the Shickshock schists with S1, form conjugate sets with steep to vertical northwest-trending kink planes. Later (?) low-dipping kink bands in Devonian argillites displace steep S2 sub-horizontally.The strain during F1 folding is not clear. F2, F3, and F4 possibly formed while near horizontal compression across axial surfaces progressively changed azimuth clockwise. The low-dipping kink bands may reflect late lateral expansion associated with uplift.
Terrestrial heat flow at Eldorado, Saskatchewan
Authors: Lewis Trevor
Published: April 2011

A heat flow of 1.2 ±.1 μcal cm−2s−1 has been measured in a mine at Eldorado, Saskatchewan. The uncertainties in the correction to this value for climatic changes caused by the most recent glaciation are a minimum at the depth at which this measurement was made. A terrestrial heat flow value, representative of the area, was obtained by using a two-dimensional conductivity model of the mine; this value is 1.3 ±.1 μcal cm−2s−1.
Densities of Precambrian rocks of the Amisk Lake – Flin Flon area. A detailed study
Authors: Gendzwill D. J.
Published: April 2011

Densities were determined for 1855 fresh bedrock samples taken from an area of about 110 sq. miles (285 km2) in east-central Saskatchewan. Average results for the region are as follows[Formula: see text]In this area, density depends primarily on the mineral composition of the rocks because their porosity is insignificant. However, the mineral composition varies widely for many reasons. Metamorphism has resulted in significant changes in rock densities because some low density minerals such as bytownite are altered to high density minerals such as zoisite. Conversely, olivine and some pyroxene are changed to low density serpentine. The density measurements are used to indicate possible subdivisions of the Amisk Group of meta-volcanic rocks. As a result, certain areas are recommended for mineral prospecting.Evidence is presented to show that some basic intrusions have increased the density of their wall rocks by metamorphism.The Bouguer gravity field in this area is closely correlated with the densities of outcropping rocks. The shape and depth of some rock units are estimated from the gravity. All the outcropping rock units extend less than 5 km in depth and some are very shallow.
Pleistocene remains of the lion-like cat (Panthera atrox) from the Yukon Territory and northern Alaska
Authors: Harington C. R.
Published: April 2011

Skull and forelimb fragments of the large, extinct cat (Panthera atrox) from Pleistocene sediments in the Dawson area, Yukon Territory, are the first records of the species for Canada. A further specimen from the Kaolak River, near the arctic coast of Alaska, significantly extends the known northward range of this cat. The species has been reported from approximately 26 localities from Alaska to Peru, and may have migrated from Eurasia just prior to the Sangamon interglacial. Data reviewed suggest that Panthera atrox from North America, the Eurasian "cave lion" Panthera leo spelaea, and the large Chinese cat Panthera youngi are conspecific.
Status of the Jurassic in the Canadian Cordillera of British Columbia, Alberta, and southern Yukon
Authors: Frebold Hans , Tipper H. W.
Published: April 2011

Jurassic index fossils of the Canadian Cordillera indicate the presence of some zones of most Jurassic stages. In this report the more important localities are listed, the source of information, published and unpublished, is indicated, and an up-dated correlation chart is presented. The importance of tectonic events and their effect on the completeness of the Jurassic fossil record and on the Jurassic paleogeography are stressed.
Arenaceous foraminifera from the Windsor Group (Middle and Upper Mississippian) of the Atlantic Provinces of Canada
Authors: Globensky Yvon
Published: April 2011

Arenaceous foraminifera have been obtained from the insoluble residues of limestones from the Windsor Group (Valmeyeran—Chesterian) of the Atlantic Provinces of Canada. From the arenaceous foraminifera fauna 10 genera and 27 species have been identified of which Saccammina sydneyensis, Tolypammina windsorensis, Tolypammina bretonensis, Reophax acadiensis, and Reophax brunswickensis are new species.Locally, the different subzones of the Windsor Group are characterized by species that have restricted ranges. The genus Reophax and species are restricted to Subzone B. The author is of the opinion that the Skir Dhu beds of northeastern Cape Breton Island belong to Subzone E of the Windsor type area.These arenaceous foraminifera appear to be the first indication of the extensions in their ranges to Middle and maybe to Upper Mississippian.This first detailed report on the arenaceous foraminifera in the Windsor Group is an important aid in correlating Middle and Upper Mississippian strata of the Atlantic Provinces.
Hornblende lineations in Trout Lake area, Lac la Ronge map sheet, Saskatchewan
Authors: Schwerdtner W. M.
Published: April 2011

Most rocks exposed in the Trout Lake Area are migmatitic gneisses severely deformed during the Hudsonian orogeny (± 1700 m.y. ago). Hornblende-bearing layers or lenses, mostly well lineated, are found throughout the entire area. The attitude(s) of the hornblende lineation (aligned prismatic grains) can be measured in every outcrop.Within cylindrical buckling folds and boudinage structures, involving hornblende-bearing rocks, the orientation of hornblende lineations is related to local directions of megascopic finite strain parallel to layering, for the main period of tectonic flow. Because the local strain ellipsoid is commonly oblique to layering, the strain ellipse parallel to layering is generally a non-principal section. The direction of its longest diameter is called M, regardless of whether it is a direction of extension, shortening or no longitudinal strain.Throughout all medium-scale folds and boudinage structures investigated, hornblende lineations are parallel to M. This relationship is considered as general, and hornblende lineations are employed as indicators of M within large-scale folds. (Other structural elements are used in distinguishing between finite extension and shortening parallel to M.) Finally, the strain pattern of the Trout Lake Area (west half) is analyzed by means of a contour map for the lineation plunge (non-statistical "plunge isogonic map" after D. Elliot 1965).The areal pattern of M contains a diagonal belt across which the plunge values tend to change "discontinuously." Because this narrow belt coincides roughly with a major branch of the Birch Rapids – Wepusko Bay fault zone, the angular "discontinuity" in the lineation map can be attributed to "late" rotational faulting.
Heat transfer during solidification of layered intrusions. I. Sheets and sills
Authors: Irvine T. N.
Published: April 2011

With the advent of crystal settling in a solidifying igneous intrusion, the roof contact of the intrusion may be continuously subjected to temperatures approaching those of the magma itself. This causes steeper temperature gradients in the roof rocks and, consequently, more rapid heat loss and solidification than would occur if the crystals were frozen to the roof. By contrast, the accumulation of crystals in the lower parts of the intrusion acts to lower the floor contact temperature and so reduces temperature gradients in the floor rocks; but since the proportion of liquid near the floor is reduced, the overall effect also is to speed solidification, specifically in this case, from the floor upwards. The present paper reviews in a qualitative way the relation between crystallization mechanisms and temperature in a magma body when crystal fractionation is a major process. It then examines quantitatively, by means of one-dimensional solutions of the heat flow equation, the influence on crystal accumulation rates and roof rock temperatures of (a) variations in magma temperature, (b) pre-intrusion temperature gradients in the roof rocks, (c) shallow emplacement, (d) formation of an upper border zone or floating of crystals, and (e) latent heat effects associated with contact metamorphism. Finally, it considers the effects of heat loss to the floor rocks on (i) crystallization in the magma above the accumulating pile of crystals, (ii) solidification of trapped pore magma, and (iii) contact metamorphism of the floor rocks. Some of the more important equations presented also apply to sills, sheets, and dikes showing no crystal fractionation.
Pleistocene Pike, Esox lucius, and Esox sp., from the Yukon Territory and Ontario
Authors: Crossman E. J. , Harington C. R.
Published: April 2011

Two fish dentary fragments from Late Pleistocene deposits in the Old Crow area, Yukon Territory are referable to the northern pike (Esox lucius). One tooth fragment from the last interglacial (Sangamon) deposits in the Don River Valley, Toronto, Ontario, is identified as Esox sp. The Yukon dentaries are the first fossils definitely attributable to Esox lucius in North America, and these records are the first for the suborder Esocoidei in Canada.
Coprolites from the Upper Cretaceous of Alberta, Canada, with a description of their microflora
Authors: Waldman M. , Hopkins Jr. W. S.
Published: April 2011

Coprolites from the Upper Cretaceous Oldman Formation of Alberta are believed to be those of small to medium-sized reptiles of aquatic habit, probably crocodiles, champsosaurs, or chelonians. The coprolites contain a microflora consisting mainly of lycopods, ferns, hem locks, and various monocotyledons and dicotyledons, but the complete absence of any macro floral material is taken as an indication that the coprolites are derived from carnivorous reptiles.
Origin of the outer part of the Laurentian Channel
Authors: King Lewis H. , MacLean Brian
Published: April 2011

In the past, four different modes of origin have been proposed for the Laurentian Channel: structural, subaerial erosion, glacial erosion, and erosion by turbidity currents. To extend our knowledge of the outer part of the Laurentian Channel and further elucidate the problem of the origin of this important topographical feature, we have employed seismic-reflection profiling techniques.Two significant sub-bottom surfaces are recognized from the profiles: (1) A more or less smooth glacial pavement across Carboniferous, Cretaceous, and Tertiary (?) strata that conforms closely to the shape of the present sea floor; (2) an older, irregular, erosional surface cut into Carboniferous and Cretaceous rocks. These channels are infilled with Tertiary sediments.Based on the evidence gained from our interpretation of the seismic records, it appears likely that the outer channel is essentially a product of subaerial and subsequent glacial erosion. It does not appear to be structurally controlled, nor does it appear to have been formed by turbidity currents.
Nodular and other Keratophyres at St. Nicolas, Quebec
Authors: Osborne F. Fitz , Laroche Paul
Published: April 2011

Sills in Cambrian sandstone at two localities provide complementary evidence for the magmatic origin of keratophyres near St. Nicolas. The thickest sill has one facies whose solids at the time it was half or somewhat more crystallized had the composition of a hornblende laugenite. The rest magma at this stage gave rise to stellate and trachytoid keratophyre characterized by chlorite and checker-board albite with some quartz. At the other locality magma approximately of the composition of the stellate keratophyre was emplaced as sills up to 4 ft (1.2 m) thick and gave rise to medium-grained keratophyre with, along the selvages or within the sills, a fine-grained variety with chlorite and nodules, up to 1 in. (2.5 cm) diameter, of plagioclase. Illite or its precursor was secreted from the sills and was replaced by a network of veins with cores of quartz and spheroids of plagioclase, of chlorite, and of carbonate.
Ion Pairing and Water Quality Measurements
Authors: Wigley T. M. L.
Published: April 2011

The effect of ion pairing on water analyses is examined. Significant changes in composition details and saturation indices can occur in waters of moderate-to-high sulfate content. Revised estimates of the equilibrium constants for gypsum and dolomite for various temperatures are presented.
A Guide to the Chemical Classification of the Common Volcanic Rocks
Authors: Irvine T. N. , Baragar W. R. A.
Published: April 2011

A system is presented whereby volcanic rocks may be classified chemically as follows:I. Subalkaline Rocks:A. Tholeiitic basalt series:Tholeiitic picrite-basalt; tholeiite; tholeiitic andesite.B. Calc-alkali series:High-alumina basalt; andesite; dacite; rhyolite.II. Alkaline Rocks:A. Alkali olivine basalt series:(1) Alkalic picrite–basalt; ankaramite; alkali basalt; hawaiite; mugearite; benmorite; trachyte.(2) Alkalic picrite–basalt; ankaramite; alkali basalt; trachybasalt; tristanite; trachyte.B. Nephelinic, leucitic, and analcitic rocks.III. Peralkaline Rocks:pantellerite, commendite, etc.
The Pedogenic Significance of Volcanic Ash Layers in the Soils of an East Slopes (Alberta) Watershed Basin
Authors: Beke G. J. , Pawluk S.
Published: April 2011

Evaluation of analytical data for a soil described in the field as an Orthic Humo-Ferric Podzol revealed the presence of a paleo-Eutric Brunisol in the lower portion of the solum. A layer of volcanic ash overlying this Brunisolic solum served as a stratigraphic marker for separating the two sola. The IIBfh and IIIBf horizons of the Orthic Humo-Ferric Podzol soil, as described in the field, met the classification requirements for podzolic B horizons. However, the depth to which processes of podzolization appeared active barely included the layer of volcanic ash, comprising the IIIBf horizon of the pedon. The development of the pronounced IVBm horizon was ascribed to paleogenesis.
Association of (Hornblende-)Garnet–Clinopyroxene "Subfacies" of Metamorphism and Anorthosite Masses
Authors: Martignole J. , Schrijver K.
Published: April 2011

Around the Adirondack (New York) and Morin (Quebec) anorthosite masses the assemblage orthopyroxene–plagioclase is replaced to some extent by the compositionally equivalent assemblage garnet-plagioclase(less calcic)-quartz(-clinopyroxene). Although the transformation is partial, the latter assemblage has been considered typomorphic for metamorphism of the (hornblende-) garnet–clinopyroxene subfacies. Characteristic for this "subfacies" are the symplectites of garnet and quartz that commonly separate (i) orthopyroxene from plagioclase and/or (ii) iron oxide from plagioclase. Clinopyroxene is generally present in rocks either with or without the symplectites.Published experimental work shows that an increase in load pressure toward the anorthosite masses at constant or slightly increasing temperature could account for the symplectites in and around these masses, and their absence remote from them. There is, however, very little independent consistent evidence for such an increase in load pressure.We offer as an alternative the explanation that the anorthosite–mangerite suite completed solidification under a load pressure of the order of 8–10 kb and retarded regional cooling sufficiently to permit the garnet–quartz-forming reactions to take place, in itself and in contiguous rocks. This explanation is supported by the fabric of the rocks, suggesting syn- and late-kinematic (re-) crystallization in the hornblende–orthopyroxene–plagioclase subfacies, and partial postkinematic adjustment to the physical conditions of the hornblende–garnet–clinopyroxene "subfacies".
The Paleomagnetism of Diabase Dikes from the Grenville Province
Authors: Murthy G. S.
Published: April 2011

A paleomagnetic study was attempted of the diabase dike swarm intruding the Grenville structural province of the Canadian Shield. Both the alternating field and thermal demagnetization studies indicated that the dikes have varying degrees of stability of magnetization. Some dikes were shown to have stable primary component of magnetization. Microscopic observations indicated that, in most cases, the primary magnetic mineral titanomagnetite was altered to titanomaghemite, probably due to low temperature oxidation. A good correlation is obtained between magnetic stability and relative abundance of titanomagnetite to titanomaghemite in that dike. The mean paleomagnetic pole for the Grenville dike swarm, which is probably of late Precambrian age, was computed to lie at 3.0° N, 29.0° W with A25 = 11.0°. Comparison of this result with other Precambrian pole positions of similar age relative to North America suggests that the dikes were intruded after the Grenville orogeny.
Late Precambrian Rocks of Eastern Avalon Peninsula, Newfoundland — A Volcanic Island Complex
Authors: Hughes C. J. , Brückner W. D.
Published: April 2011

A model of island volcanism is presented in which rocks are referred to (1) a "syn-volcanic" constructional phase represented by rocks of four penecontemporaneous facies—vent, alluvial, marine, and plutonic—whose interrelationships are discussed and (2) a "post-volcanic" destructional phase of erosion and sedimentation accompanied by isostatic adjustment resulting in the spreading of an apron of volcanic sediments around a slowly rising and eroding island core.The late Precambrian rocks of the eastern part of the Avalon Peninsula, southeasternmost Newfoundland, are shown to fit this model rather closely, both petrographically and in their distribution and field relationships. The Harbour Main Group of volcanic rocks, the Conception Group of marine volcanic sediments and tuffs, and the Holyrood Plutonic Series, dated at 574 ± 11 m.y., were all formed during the syn-volcanic constructional phase. Their apparently conflicting age relationships can be reconciled to the view that they are penecontemporaneous facies. The Cabot and Hodgewater Groups of marine and alluvial volcanic sediments were formed during the post-volcanic destructional phase. Apart from vertical crustal movements, only minor diastrophic deformation appears to have occurred during these two phases.This model of volcanic island environment may help in interpreting the geology of several other belts in eastern and central Newfoundland comprising late Precambrian and Paleozoic volcanic rocks and sediments.
Triassic Time and Ammonoids: Problems and Proposals
Authors: Tozer E. T.
Published: April 2011

Problems arising from the classification and dating of Triassic rocks and ammonoids are reviewed. It is emphasized that all chronostratigraphic units must be based on stratotypes in order to achieve an unambiguous time scale. Explanations are sought for anomalies encountered when comparing ammonoid age ranges determined in North America with alleged ranges based on European and Asian occurrences. Most can be resolved by taking into account recent research on penecontemporaneous solution processes or by invoking condensation. Both have resulted in the mixing of natural faunas at European and Asian localities. Review of problems of ammonoid classification and taxonomy indicates that the recognition of a variable species is only possible when the full range of variation has been established in a population, i.e. from a series of specimens of one age obtained from one place. For discriminating higher taxa the evidence indicates that no single character, of either the inner of outer whorl, is of overriding significance for determining phylogenetic relationships. The total absence of marine Triassic rocks on the Atlantic shores supports the conclusion that this Ocean did not exist in Triassic time, but distribution of ammonoids provides some evidence to suggest that Laurasia and Gondwanaland may have been separated in the Middle Triassic. It is suggested that Triassic limestone in red Hallstatt facies may be encountered by the Deep Sea Drilling Project in Wharton Basin, west of Australia. Appendixes include: I, a discussion of the Triassic Time Scale; II, a new classification of all Triassic Ammonoidea; III, diagnoses of new taxa (seven new families, three new subfamilies, and nine new genera).
Application of H218O/H216O Abundances to the Problem of Lateral Mixing in the Liard–Mackenzie River System
Authors: Krouse H. R. , Mackay J. Ross
Published: April 2011

Relative H218O/H216O abundances were determined in 10 cross-sectional profiles of the Liard–Mackenzie River system sampled during June, 1970 at various intervals over 300 miles (480 km) distance downstream from their confluence. At their confluence, the Liard and the Mackenzie Rivers had average δH218O values of −21.3‰ and −17.4‰ SMOW respectively. Thus, lateral mixing of the two waters could be monitored isotopically. The data show that a distance of the order of 200 miles (320 km) was required for thorough lateral mixing.
Age of the Early Precambrian Rocks of the Saganaga Lake – Northern Light Lake Area, Ontario–Minnesota
Authors: Hanson G. N. , Goldich S. S. , Arth J. G. , Yardley D. H.
Published: April 2011

Whole-rock Rb–Sr isochron and mineral ages from the Saganaga Lake – Northern Light Lake area on the Ontario–Minnesota boundary indicate a major orogeny at 2700 m.y. ago. The sequence of events reconstructed in the geologic history started with the eruption of a volcanic pile of flows and pyroclastic material. During metamorphism and folding the basalt flows were converted to amphibolite and an interlayered series to the Northern Light Gneiss, which is now principally trondhjemite with lesser amounts of amphibolite and metarhyolite. The greenstones and the Northern Light Gneiss were intruded by the Saganaga Granite (tonalite), and the tonalite and the Northern Light Gneiss, in turn, were intruded by a syenodioritic phase of the lcarus pluton.The whole-rock isochron ages for the Northern Light Gneiss, the Saganaga tonalite, and the lcarus pluton are 2740, 2710, and 2690 m.y., respectively. Large uncertainties are attached to these values because of the unfavorable Rb/Sr ratios, but the mineral data that include Rb–Sr, K–Ar, and U–Pb analyses, together with geologic observations, permit dating of the Saganaga tonalite at 2700 ± 50 m.y.Mineral ages from this study and some published by the Geological Survey of Canada cluster in the range from 2650 to 2600 m.y. ago and may indicate h low-grade event or an epeirogenetic effect that dates the time of uncovering and stabilization of the region. Mineral ages in the range from 2600 to 2400 m.y. and at approximately 1800 m.y. ago may be partially reset and probably reflect local conditions of faulting and shearing associated with hydrothermal alteration, later low-grade metamorphism, and possibly recent weathering. Similarly, faults and sheared zones probably were effective in localizing the intrusion of dikes that occurred at various times between 2700 and 1100 m.y. ago.
The Nature of Mercury Anomalies of Two Intrusive Complexes, Rougemont and Lake Dufault, Quebec, by Multielement Analysis
Authors: Webber G. R. , Newbury M. L.
Published: April 2011

Rock samples from the Lake Dufault granodiorite near Noranda, Quebec, and from a Monteregian intrusive (Rougemont) were analyzed for mercury and several other elements. Statistical treatment of the data by multiple regression and factor analysis may enable discrimination between anomalies of contrasting natures such as those of vapor and liquid transportation.
Southeastern Atlantic Canada, Northwestern Africa, and Continental Drift
Authors: Schenk Paul E.
Published: April 2011

The model applies plate-tectonics to explain the geologic evolution of southeastern Atlantic Canada and northwestern Africa. The North Atlantic may have opened and closed several times from the middle Cryptozoic to the present. Closings of the ocean caused collisions between continents and also island arcs. Openings were ragged so that parts of one continent were transposed to the other, and sialic fragments became offshore micro-continents. Africa has progressively lost increments of continental crust to North America.Precambrian blocks of southeastern Atlantic Canada may be remnants of an African shelf. which was crumpled during a billion-year old continental collision (Grenville orogeny). After ragged rifting during the Late Precambrian these fragmentary blocks were carried eastward as micro-continents off Africa. Both early (Danakil Alps of the Red Sea) and late-stage (Canary Islands) recent analogues appear valid. The micro-continents ponded turbidites, which formed rise-complexes off Africa. Continental glaciations in the Late Precambrian and Late Ordovician not only make excellent inter-regional chronostratigraphic units in almost unfossiliferous strata. but also may confirm the African origin of Nova Scotia. Subducting plate-margins increased offshore volcanism and narrowed the Paleozoic Atlantic. Late Paleozoic continental collision again between Africa and North America sandwiched the micro-continent, telescoped the sedimentary/volcanic complexes, and flooded the sutured area with granodiorite. Middle Carboniferous carbonates and sulfates record vestiges of the Paleozoic Atlantic, and mixing of the Euro-African fauna with that of the western Paleozoic Atlantic of the northwestern Appalachians. The Atlantic was closed at least along the latitude of Atlantic Canada and Morocco. During the Mesozoic, an accreting margin uplifted this area, quickened redbed deposition and volcanism, initiated restricted marine sedimentation, and inaugurated the present North Atlantic east of the African remnant of southeastern Atlantic Canada.
Radiometric Age Determinations from the Long Range Mountains, Newfoundland
Authors: Pringle I. R. , Miller J. A. , Warrell D. M.
Published: April 2011

Foliated granite plutons in the Long Range give a Rb–Sr whole rock age of 1130 ± 90 m.y. and a K–Ar biotite age of 840 ± 20 m.y. These ages agree with other Grenville dates and may be fitted into the Grenville pattern. The K–Ar age of 805 ± 35 m.y. for the diabase dike swarm is also taken as the age of the Lighthouse Cove Formation on Belle Isle. This demonstrates that there is probably a non-sequence between this formation and the overlying Lower Cambrian sediments. The low initial 87Sr/86Sr ratio of 0.702 ± 0.004 indicates that these dikes have a deep crustal or mantle origin.
The Great Logan Paleomagnetic Loop — The Polar Wandering Path from Canadian Shield Rocks During the Neohelikian Era
Authors: Robertson W. A. , Fahrig W. F.
Published: April 2011

Normally magnetized dikes and reversely magnetized sills of Neohelikian age near the northwest shore of Lake Superior form two distinct paleomagnetic groups with mean pole positions of 179° W, 35° N, and 140° W, 47° N respectively. Thermal and alternating field demagnetization and the study of magnetic properties and opaque minerals indicate that directions of magnetization of these rocks were acquired at the time of their intrusion. Field evidence suggests that the sills are older than the dikes and radiogenic age determinations indicate that the intrusion of both occurred between 1000 and 1100 m.y. ago.These pole positions, together with those for the Franklin intrusions pole at 167° E, 08° N (675 m.y.), the Abitibi dikes, at 134° W, 27° N (1150 m.y.), and the Mackenzie igneous events, at 171° W, 4° N (1200 m.y.) are used to define the Logan Loop, the path that the pole took in Neohelikian time relative to the Canadian Shield. Other poles well defined magnetically, but less well dated, from rocks of this era, fit the curve quite well.Analysis of available data supports the hypothesis that the relative polar movement that gave rise to the Logan Loop was preceded and followed by polar stability vis à vis North America, whereas polar movement may have been quite rapid during the formation of the loop, which coincided with the time of the Grenvillian orogeny. Comparison of the depositional environment of Neohelikian rocks of the Canadian Shield with their probable paleolatitude as indicated by the 5 key points on Logan Loop should provide a test for the validity of this movement.
Conodonts from the March and Oxford Formations in the Brockville Area, Ontario
Authors: Greggs Robert G. , Bond Ivor J.
Published: April 2011

Conodont faunas from the March and Oxford Formations of the Brockville area, southeastern Ontario, are described. The specimens are assigned to fifteen species comprising eight genera.The Nepean sandstone, at the bottom of the Paleozoic section, has a thick conglomerate at its base; the overlying sandstones are burrowed and probably of marine origin.Basal March sandstones are blue–gray in color and have been extremely bioturbated. The higher standstones are orthoquartzites with minor burrowing. Both are probably offshore deposits.The Oxford Formation comprises sandy limestones and dolomites as the dominant lithologies. It was probably deposited on a tidal or intertidal flat.The conodont faunas indicate that the March Formation is probably late Tremadocian in age, and that the Oxford Formation is Arenig in age. The Nepean sandstone yielded no conodonts.The March and Oxford conodont faunas are correlated with those from the Columbia Icefields section, Alberta; the House limestone, western Utah; the El Paso Formation of Arizona; the Oneota and Shakopee Formations of the Upper Mississipi valley; and the St. George Formation, Newfoundland.Genera of European affinity are absent and a closer tie with contemporaneous continental North American faunas is suggested.The oldest occurrence of the genus Strachanognathus in this region is noted.
Upper Trenton Conodonts from the Grondines Section of Quebec
Authors: Globensky Yvon , Jauffred Jean-Claude
Published: April 2011

The conodonts of the Grondines Section, a good representative section of the upper Trenton of the Neuville Formation in the St. Lawrence Lowlands of Quebec, are similar to those of the Neuville Section. From 667 specimens collected, 24 genera and 27 species were identified. Three of Bergström and Sweet's assemblages are recognized. Only one genus and two species not described in the Neuville fauna are found in the Grondines section.
Quantitative Determination of some Carbonate Minerals in Greenschist Facies Meta-volcanic Rocks
Authors: Bristol Calvert C.
Published: April 2011

X-ray powder diffraction methods, successful in quantitative determination of silicate minerals in fine-grained rocks, have been applied to the determination of calcite, dolomite, and magnesite in greenschist facies meta-volcanic rocks. Internal standard graphs employing two standards (NaCl and Mo) have been determined.Carbonate mineral modes (calcite and dolomite) for 6 greenschist facies meta-volcanic rocks obtained by the X-ray powder method have been compared to normative carbonate mineral contents calculated for the same rocks. This comparison showed a maximum variation of 7.7 wt.% between the X-ray modes and the normative carbonate mineral contents of the rocks. Maximum standard deviation for the X-ray modes of these rocks was equivalent to 4.4 wt.%.
Stratigraphy of the Fort Qu'Appelle Vertebrate Fossil Locality, Saskatchewan
Authors: Christiansen E. A.
Published: April 2011

The Fort Qu'Appelle vertebrate fossil locality is in the Echo Lake Gravel, which lies between tills of the Sutherland and Saskatoon Groups. Biostratigraphers have indicated that the Echo Lake Gravel is either a Sangamonian deposit or a Wisconsin an interstadial deposit. The physical evidence however, suggests that the gravel is an outwash deposit which was deposited at the close of an interglacial or interstadial interval during the advance of the glacier that deposited the Floral Formation.
Hydrological Observations on a Small Arctic Catchment, Devon Island
Authors: McCann S. B. , Cogley J. G.
Published: April 2011

The annual hydrological régime of "Jason's Creek" begins in June or early July with a 10–15 day period of flooding as a result of snowmelt, preceded by a few days of relatively low flow. In 1970, 82% of the annual snowmelt discharge left the basin between June 26 and July 15. After the flood, discharge decreases irregularly but in a roughly asymptotic fashion until the stream freezes to its bed in late August or early September. This régime is punctuated by occasional rainstorm floods. The flow of the stream varies diurnally in response to radiative and thermal inputs of energy to the basin snowpack, the lag time for these inputs being 5 h. The response of the basin to an input of rainfall is rapid and the duration of direct storm runoff short. Sparseness of vegetation and shallowness of the active layer above the permafrost are important properties of the drainage basin.
Age Determinations in the Circum – Ungava Geosyncline and the Evolution of Precambrian Banded Iron-Formations
Authors: Fryer B. J.
Published: April 2011

Rb-Sr whole-rock isochron studies on volcanic and sedimentary rocks from the Belcher Fold Belt in Hudson Bay, and sedimentary rocks from the Labrador Trough and the Lake Mistassini area of Quebec, yield ages of 1800, 1870, and 1790 m.y., respectively. These age determinations substantiate previous correlations between these areas based on stratigraphic and structural similarities. Consequently, the concept of a Circum – Ungava Geosyncline appears to be valid on geochronological grounds, with geosynclinal development terminating with the onset of the Hudsonian orogeny at about 1800 m.y.The Circum – Ungava Geosyncline contains banded iron-formations exhibiting shallow-water sedimentary structures which distinguish them from older banded iron-formations. These deposits probably represent the hydrospheric response to the initial large scale introduction of oxygen to the atmosphere by evolving life forms. Because of their probable unique nature these younger banded iron-formations may serve as a valuable marker horizon for global correlations of Proterozoic strata.
Downward Intrusive Breccias in the Huronian Espanola Formation, Ontario, Canada
Authors: Young Grant M.
Published: April 2011

Some breccias in the early Aphebian Espanola Formation of the north shore of Lake Huron apparently formed by downward injection caused by sudden release of high pore pressures in water saturated sediments. Pressure release was effected by movement of sediment-water mixtures into fissures formed in the Espanola Formation by early (probably pre-Gowganda) tectonic movements.