bluuebunny/crossref_metadata_2025 huggingface dataset:
Late glacial and post-glacial history and emergence of the Ottawa Islands, Hudson Bay, Northwest Territories: Evidence on the deglaciation of Hudson Bay
Authors: Andrews J. T. , Falconer G.
Published: April 2011

The Ottawa Islands are in the northeastern part of Hudson Bay. Evidence from crossing striations suggests that the earliest recorded glacial movement was toward the northeast. With deglaciation of Hudson Strait and central Hudson Bay the ice movement shifted progressively in an anti-clockwise direction, with the final movement being toward the west–southwest. The islands were deglaciated between 7610 and 7250 radiocarbon years ago. The marine limit is 158 m above sea level. Deltaic deposits below the marine limit are grouped into sets that correlate with glacial advances in Labrador–Ungava and Baffin Island, and with palynological results from Keewatin, suggesting that they reflect climatically induced processes rather than a balance in eustatic–isostatic movements. Radiocarbon dates on marine molluscs enable postglacial uplift and emergence curves to be drawn, which agree closely with predicted curves. Rates of uplift were about 0.06 m yr−1 at 6500 yr B.P., whereas the present rate is about 0.008 m yr−1. The deglaciation of Hudson Bay was marked by the splitting of the ice sheet along the submarine deep that trends southward between Mansel and Coats islands toward the southwest coast of the bay.
Gravity variations and precipitation onset
Authors: Gendzwill D. J. , Maybank J.
Published: April 2011

Times of occurrence of maximum tidal gravity and maximum rate of change of this parameter are compared with times of rainshower onset at Saskatoon. It is concluded that no correlation exists at this location between the former and the latter data. A previous report that rain onset did tend to coincide with maximum rate of change of gravity at Pisa is compared with these present calculations and shown to be erroneous.
The analcite-bearing volcanic rocks of the Crowsnest Formation, Alberta
Authors: Pearce T. H.
Published: April 2011

The lower Cretaceous Crowsnest Formation of the Crowsnest Pass area, Alberta, is predominantly trachytic, but some sodic, analcite-rich, rocks occur. It consists of bedded pyroclastic and epiclastic material with minor flows and dikes. Most of the volcanism appears to have been explosive in nature. Almost all the igneous material is porphyry tic; nearly all the phenocrysts are zoned, and evidence of resorption is common. Sanidine phenocrysts show evidence of repeated growth and solution with as many as 60 cycles per crystal. The primary, igneous, analcite phenocrysts of the analcite phonolites and blairmorites crystallized at depth, and were preserved by rapid vertical transport and quenching at the surface. In many cases, however, partial or complete decomposition of the crystals occurred, and thermal discoloration of the analcite can be reproduced in the laboratory.
Pentlandite phase relations in the Fe–Ni–S system and notes on the monosulfide solid solution
Authors: Shewman R. W. , Clark L. A.
Published: April 2011

A curve relating composition of synthetic pentlandite with interplanar spacing was determined experimentally as follows: d115 = 1.9407 – 0.0023x + 0.0077x2, where x represents the iron to nickel weight ratio with d115 measured in Å and the sulfur content is fixed at 33.05 wt %. The following iron, nickel, and sulfur solid solubility limits of pentlandite were determined:[Formula: see text]X-ray powder patterns of monosulfide solid solution heated at 500 and 400 °C with a composition (wt %) of 18.8 Fe, 43.8 Ni and 37.4 S showed a modulated structure. A solvus interrupts the monosulfide solid solution at 275 ± 10 °C and the approximate composition in wt %: Fe = 22.5, Ni = 40, and S = 37.5.The relatively common occurrence of the pyrite–pentlandite assemblage in nickel ores shows that the solid state reactions attendant upon cooling of these ores, proceed to temperatures at least below 200 °C.
Lateral mixing of the Liard and Mackenzie rivers downstream from their confluence
Authors: Mackay J. Ross
Published: April 2011

Data relating to the mixing rate of the Liard and Mackenzie Rivers were collected in June 1968, for a distance of 300 miles (~482.8 km) downstream from their confluence. Samples were collected from 11 cross sections, spaced about 30 miles (~48.3 km) apart. At each cross section, 5 surface samples and 3 subsurface samples from a depth of 20 ft (~6 m) were collected, to give a total of 88 samples.The temperatures at the 88 sample points were measured in place. Secchi disk transparency readings were taken for the 55 surface sites. Water samples collected at the 88 sites were laboratory tested for their turbidity, conductivity, and sodium and chloride concentrations.Analyses of the results show that the Mackenzie and Liard waters were not fully mixed some 300 miles (~482.8 km) downstream from their confluence. Some overflow and underflow, due to density differences, probably occurred.Quite possibly the long distance required for mixing may be more common, in large broad rivers, than is generally realized.
Three-dimensional gravity interpretations of the Round Lake batholith, northeastern Ontario
Authors: Gibb R. A. , Boeckel J. van
Published: April 2011

Gravity surveys of the Timmins–Senneterre mining belt of northeastern Ontario and western Quebec were made by the Dominion Observatory during the period 1946–1964. The Round Lake batholith is one of several composite granitic plutons of the Algoman series which are outlined by intense negative gravity anomalies. The anomaly over the Round Lake batholith can be explained by the large density contrast (0.22 g/cm3) between the granite and surrounding Keewatin volcanic rocks.Two possible models of the batholith are presented which depend on different assumptions as to the composition of the upper crust. The first model involves normal faulting of the batholith to explain the variations in anomaly level within the batholith. In this model the granite is assumed to be homogeneous in density and extends to a maximum depth of 10 km. Alternatively density variations corresponding to a facies change within the pluton may be the major cause of the local internal anomaly variations. In this interpretation the true thickness of the granite cannot be evaluated as the whole region is assumed to be underlain by granite, but the maximum thickness of the surrounding basic volcanic rocks is 5 km.
A skeletal reconstruction of Leptoceratops gracilis from the upper Edmonton Formation (Cretaceous) of Alberta
Authors: Russell Dale A.
Published: April 2011

A skeletal reconstruction of the small protoceratopsian dinosaur Leptoceratops gracilis from the latest Cretaceous of Alberta is presented. Leptoceratops has a greater number of presacral vertebrae than in other known protoceratopsids, and the presacral vertebral count is recognized to be somewhat variable in ceratopsids as well. Psittacosaurids, protoceratopsids, and ceratopsids represent distinct lineages of the same general group of ornithischian dinosaurs.
Deformation history in part of the Lubec–Belleisle zone of southern New Brunswick
Authors: Brown R. L. , Helmstaedt H.
Published: April 2011

Rocks of the Proterozoic Coldbrook Group on the north shore of the Bay of Fundy, New Brunswick, are bounded to the north by a major northeast trending fault (Lubec–Belleisle). North of the fault Paleozoic rocks of the Mascarene Group are overlain unconformably by Upper Devonian and Lower Carboniferous strata.Both the Coldbrook and Mascarene Groups have been deformed by three phases of deformation. Deformation of the two Groups was coeval; penetrative fabrics first developed during the Acadian (Middle Devonian) orogeny.Pre-Acadian Paleozoic movements were limited to local or regional uplift with possible attendant warping and/or gentle tilting.Mylonitic fabrics formed in Coldbrook rocks during the first two phases of the Acadian polyphase deformation. These northeast trending s- surfaces lie normal to the direction of maximum finite shortening. Also from the orientation of synmylonization quartz deformation lamellae of the second phase, it is apparent that the local trajectory of the maximum principal stress was normal to the s-surfaces of the mylonites.No evidence for major northeast–southwest strike slip faulting has been found. Fracture analyses in Upper Devonian and Lower Carboniferous rocks in the northeast trending fault zone, point to a northwest trending principal compressive stress.It is contended that the bulk of the ductile strain (first two phases) occurred In response to northwest principal compressive stress during the Middle Devonian, and these stresses were re-established in post-Devonian times, resulting in the development of high angle oblique to dip slip movements on the northeast trending faults.
An isostatic origin for basement uplifts
Authors: Walcott R. I.
Published: April 2011

The tectonics involved in the structural development of uplifts in the stable platforms are suggested to be a natural consequence of loading the platform by sedimentary rocks. Any original compensated topography on the platform will cause differential loading with sediments thicker and the load greater in the valleys than over the hills. If the wavelength of topography is large, differential vertical movements can occur causing an amplification of the original topography and the growth of an arch. If the wavelength lies in a critical region defined by the flexural rigidity of the lithosphere, stress differences within the lithosphere caused by the loading may exceed the elastic limit producing faulting and the development of horsts. The Boothia Uplift, the Early and Middle Paleozoic development of the Peace River Uplift and other structures in Canada are suggested to be examples of such a process.
Upper Devonian (Frasnian) algae and foraminifera from the Ancient Wall carbonate complex, Jasper National Park, Alberta, Canada
Authors: Toomey Donald Francis , Mountjoy Eric W. , MacKenzie Warren S.
Published: April 2011

Marine algae and foraminifers occur in the Ancient Wall carbonate complex of Upper Devonian (Frasnian) age in Jasper National Park, Alberta, Canada. This microbiota is the most diverse and abundant yet described and illustrated from North America; it closely resembles other microbiotas from the Upper Devonian of Western Australia and the Volga–Urals region of the Soviet Union.Strata of the Ancient Wall complex comprise two formations each with two members. They are: the Cairn Formation with a lower Flume Member and an upper member and the overlying Southesk Formation with a lower member and an upper Simla Member. A biota of 15 genera and 21 species is recorded from these rocks. The forms grouped under the algae are: Vermiporella sp., Girvanella sp., Sphaerocodium sp., Renalcis sp. cf. R. turbitus Wray, R. sp., radiosphaerid calcispheres, and algal? borings. The calcareous foraminifers are: Parathurammina sp. cf. P. spinosa Lipina, P. sp., Bisphaera sp., lagenid-like form, Paratikhinella sp. cf. P. cannula (Bykova), P. sp., Tikhinella sp. cf. T. measpis Bykova, T. sp., Evlania? sp., Eonodosaria sp. cf. E. evlanensis Bykova, E. sp., Multiseptida sp. cf. M. corallina Bykova, M. sp., and Nanicella sp.Calcareous foraminifers, dominantly parathuramminids, comprise about two-thirds of the total biota. The remaining one-third consists of algae, amongst which radiosphaerid calcispheres are the most abundant. The relatively primitive parathuramminids are more numerous in the Cairn Formation, whereas more advanced foraminifers such as tikhinellids, eonodosarids, and multiseptids occur more frequently in the overlying Southesk Formation. There is also an appreciable increase in foraminiferal diversity between the basal Flume Member and upper member of the Cairn Formation. Radiosphaerid calcispheres and parathuramminids are most numerous in skeletal wackestones and tikhinellids, eonodosarids, and multiseptids in less muddy packstones and grainstones.Study of this biota substantiates previous interpretations of the depositional environment based on stratigraphic and petrographic evidence. In general, these indicate shallow-water environments for both the Cairn and Southesk Formations, with the packstones and grainstones, which occur more frequently in the Southesk Formation, indicative of more agitated and presumably shallower waters.
Ore-densities of thirty-seven Canadian base-metal sulfide deposits
Authors: Anderson C. D. , Sherwood H. G.
Published: April 2011

Ore-density measurements were made on representative samples from thirty-seven base-metal deposits. Thirty-five of these samples were mill-feed composites and two were drill-core composites. The values obtained ranged from 2.73 g/cm3 to 4.53 g/cm3. The median density was 3.20 g/cm3.
A late, postglacial horse from Pashley, Alberta
Authors: Churcher C. S. , Stalker A. MacS.
Published: April 2011

Elements from the left hind foot of a small horse, probably Equus conversidens Owen, are reported from a few miles southeast of Medicine Hat, Alberta. The bones were found below a buried soil contained within an eastward-striking glacial spillway. A date of about 8000 y B.P. is suggested for the specimens on stratigraphic considerations. If this date is correct, these bones probably represent the youngest indigenous fossil horse known in North America.
Acritarchs from the Lower Silurian Neahga Formation, Niagara Peninsula, North America
Authors: Cramer Fritz H. , Cramer María del Carmen R. Díez de
Published: April 2011

Palynomorph assemblages were extracted from twenty-two samples of the late Lower Silurian Neahga Formation of the Niagara Peninsula. Acritarchs are abundant and well preserved; chitinozoans are relatively rare and mostly incomplete; plant spores are absent; microfossils with leiosphere and tasmanites affinities are also abundant.Comparison of the assemblage composition within the formation in either regional or chronological sense failed to show consistent, reproducible, qualitative, or quantitative differences. There are consistent quantitative composition differences between assemblages of the practically age-equivalent Maplewood and Neahga Formations. The Neahga assemblages are easily differentiated qualitatively from those of the underlying and overlying Silurian formations.Extrapolation from the biofacies boundary transgression during the Silurian, places the age of the Neahga Formation at or before Elles and Wood's graptolite zone 21.
Gamma-ray spectrometer calibration for field analysis of thorium, uranium and potassium
Authors: Killeen P. G. , Carmichael C. M.
Published: April 2011

The calibration of a portable three-channel gamma-ray spectrometer for in situ analysis of thorium, uranium, and potassium is discussed. A method of regression analysis is suggested as the best means of including all of the data available from the calibration stations. Calibration indicates a nonlinear relation between count rates obtained in the field and concentrations in parts per million obtained from laboratory analysis. The range of radioelement content must be taken into consideration and appropriate sets of calibration constants applied. As an example of the method, calibration constants are calculated for a portable gamma-ray spectrometer using data for the Blind River uranium region of Ontario.
Correlation of the Upper Cretaceous Montana Group between southern Alberta and Montana
Authors: Russell Loris S.
Published: April 2011

Critical comparisons of Montanan sequences in southern Alberta and various parts of Montana permit some conclusions on north–south, as well as east–west, correlation. The Lower Milk River sandstone of Alberta is the equivalent of the Lower Eagle sandstone of northwestern Montana but both differ from the type Virgelle Sandstone, with which they have been equated. The Pakowki Formation of Alberta represents the Claggett of Montana plus lower parts of the Judith River Formation. The remainder of the Judith River Formation is equivalent to the Foremost and Oldman Formations of Alberta. The Bearpaw Formation thins markedly from east to west, and uppermost shales pass into marine sandstones and these in turn into non-marine formations. Of the various formational boundaries, the top of the Lower Milk River and Lower Eagle sandstone, the base of the Pakowki and Claggett Shale, and the top of the Oldman and Judith River Formations, are also time boundaries throughout large parts of the region.
Les schistes cristallins Grenvilliens de la région du Lac McGillivray
Authors: Pourret G. , Bergeron R.
Published: April 2011

The principal formations of the Lac McGillivray region are biotite and amphibole gneiss. They contain levels of leptynites, amphibolites, meta-gabbro, and pyroxene gneiss. This series can be considered of sedimentary origin and the agreement with the diagrams ACF and A′KF of the chemical analyses permits a comparison between the different formations of the gray-wackes and those of the marl. Some pyroxene amphibolites and the metagabbros show evidence of weak magnetic activity during sedimentation.The following parageneses characterize an amphibolite facies type of metamorphism: Quartz — Plagioclase — (Microcline) — Biotite — (Almandine) — (Muscovite), Quartz — Plagioclase — (Microcline) — Biotite — Hornblende — (Almandine) — (Muscovite), Quartz — Plagioclase — (Almandine) — Hornblende — (Diopside).Three principal phases of flexible deformations are in evidence: (a) an axial folding N 90° of which the traces are strongly obliterated, (b) an axial folding N 40°–N 60°, and (c) an axial folding N 130°–N 150° with very distinct traces, because it is the last one.The intersection of the last two fold-sets brought about the formation of domes or of structures of short elongation. Two kinds of fractures, N–S and E–W, are the last tectonic events of this region.
K–Ar ages of plutonic rocks between Hope, British Columbia, and the 49th parallel
Authors: Richards T. , White Wm. H.
Published: April 2011

Twenty-two new K–Ar age determinations are reported for the plutonic rocks between Hope, B.C. and the 49th parallel. Ages ranging from 103 m.y. to 16 m.y. suggest an extension in southern British Columbia of Mesozoic plutonism into Late Cretaceous time and three brief and well-defined Tertiary plutonic events.
A new analysis of geomagnetic depth-sounding data from western Canada
Authors: Cochrane N. A. , Hyndman R. D.
Published: April 2011

Time varying geomagnetic fields observed in southern British Columbia and Alberta are analyzed using optimum "transfer function" techniques for periods from 4 to 240 min. Estimates of the frequency and spatial dependence of the "coast effect" are obtained. Inland anomalies are delineated and attributed to variations in conductivity in the upper-to-middle crust coupled with an abrupt east–west transition in deeper conductivity. Regional attenuation of the uncorrelated portion of the vertical magnetic component is indicative of high conductivity near the crust mantle transition zone under the western part of the Cordillera. The conclusion is in agreement with magnetotelluric observations and other geophysical data.
Variation in the composition of muscovite and albite in a pegmatite dike near Yellowknife
Authors: Kretz Ralph
Published: April 2011

Regular and irregular variations were found in the concentration of elements in muscovite and albite in relation to the distance from margin to center of a pegmatite dike near Yellow knife. For example, the magnesium content of muscovite increases towards the center, iron decreases, and lithium varies irregularly.The distribution of sodium and potassium among muscovite, albite, and potassium feldspar is considered in relation to mineral reactions and phase equilibrium. Comparison with experimental data indicates that the pegmatite specimens attained near-equilibrium at approximately 450 °C.
Herpetofauna of the Wood Mountain Formation (Upper Miocene) of Saskatchewan
Authors: Holman J. Alan
Published: April 2011

An Upper Miocene deposit, the Kleinfelder Farm locality of the Wood Mountain Formation near Rockglen, Saskatchewan, yielded two anurans, an unidentified turtle, an unidentified crocodilian, two lizards, and five snakes. All of the identifiable forms, with the exception of two colubrid snakes, represent living genera, and some are close to modern subgenera or to modern species. A species of glass lizard (Ophisaurus) and a genus of racer-like colubrid snake are new. The glass lizard may be ancestral to the two modern species, O. ventralis and O. attenuatus, but the affinities of the racer-like colubrid are not well understood. The climate of the region must have been much warmer than today and east and west rainfall zonation on the continent may have been less pronounced than at present. The Kleinfelder Farm locality herpetofauna shows similarities to the Norden Bridge Quarry herpetofauna of the Valentine Formation of Brown County, Nebraska, but the Kleinfelder site may be somewhat older.
The relationship between sulfide grain size and metamorphic grade of host rocks in some strata-bound pyritic ores
Authors: Tempelman-Kluit Dirk J.
Published: April 2011

New data concerning the grain size of sulfide minerals in some ore deposits surrounded by metamorphosed silicate host rocks is presented. These indicate that average grain size of ore and grain size range of individual sulfide minerals show fair correlation with metamorphic grade of host rocks.
Fracture zones on the Mid-Atlantic Ridge between 43° N and 44° N
Authors: Keen M. J.
Published: April 2011

A seismic reflection profile across the fracture zones on the Mid-Atlantic Ridge between 43° N and 44° N shows that the thickness of sediment increases markedly south of the fracture zone at 43° 05′ N on the eastern flank of the ridge. The thickness there is in accord with observations made west of the ridge in the region of the survey at 45° N. This suggests that the effects of rates of sea-floor spreading and sedimentation have been similar on this eastern part of the ridge to those west of the ridge farther north.
Rayleigh wave propagation and perturbed boundaries
Authors: Thapar M. R.
Published: April 2011

This paper presents theoretical and experimental studies of the propagation of Rayleigh waves along perturbed boundaries. In the theoretical treatment, the boundary conditions necessary for the propagation of Rayleigh waves are expressed in terms of the shape of the perturbed boundary. Then by applying a perturbation theory, and the Fourier Integral theorem, the perturbed parts of the solutions to the wave equation are obtained in the integral form. The perturbed contributions to the components of strain are obtained by the use of a numerical integration technique. The experiments are conducted on two dimensional ultrasonic models using plexiglass and plaster of paris as the modeling materials. The theoretical and experimental results for the perturbed half-space model and the model of a layer over a perturbed half-space, are in good agreement. In general, the results show an amplification of the strain amplitudes of Rayleigh waves along the Gaussian perturbation in the first model and along the free surface in the second model, in the direction of propagation.
An improved rainfall simulator for use in erosion research
Authors: Bryan Rorke B.
Published: April 2011

Artificial simulation of rainfall to produce controlled conditions is increasing in importance both as a laboratory and field research tool in a variety of disciplines. The development of a compact laboratory rainfall simulator for use in erosion research is described. This unit is capable of producing rainfall intensities from 1.27 to 91 cm/h with raindrops ranging from 0.50 to 5.28 mm in diameter. In an available fall height of 2.59 m these drops achieve estimated velocities ranging from 100 to 69.3% of terminal velocity. Rainfall characteristics produced are critically reviewed and laboratory operating procedures are described.
Geomagnetic induction anomaly near Kootenay Lake—a strike–slip feature in the lower crust?
Authors: Lajoie J. J. , Caner B.
Published: April 2011

A geomagnetic induction anomaly in southeastern British Columbia has been investigated in detail with a 20-station network. The results indicate a sharp (near vertical) discontinuity in deep electrical conductivity structure, trending roughly east–west and located at the south end of Kootenay Lake. It is interpreted as evidence for sinistral strike–slip which intersected the edge of the main conductive layer which underlies most of the western Cordillera.Geological evidence indicates that such a feature (which has no known surface expression) must predate the late Paleozoic or early Mesozoic (200–250 m.y.). The persistence of sharp discontinuities over such long periods would confirm the compositional, rather than thermal, nature of the lower crustal conductive layer under the western Cordillera.
Variation in Degree of Hornblende Grain Alignment within two Boudinage Structures
Authors: Schwerdtner W. M. , Sheehan P. M. , Rucklidge J. C.
Published: April 2011

The degree of preferred orientation of hornblende in two boudinage structures is analyzed by means of an X-ray texture goniometer. Relative values of reflected intensity for {110} are plotted on the stereographic net, and contoured at convenient intervals. As in conventional fabric diagrams for hornblende, {110} define a great-circle girdle whose breadth reveals the density of unimodal grouping of [001].The density of grouping of [001] varies throughout both boudinage structures. It decreases with increasing extension in structure A, and seems to have a similar trend in structure B, where the determined variation in degree of grain alignment is of doubtful statistical significance.The inverse relationship between the degree of preferred orientation and the magnitude of extension may be attributed to rotation of the principal directions of finite strain during syntectonic crystallization. Alternatively, reorientation of strained grains by annealing recrystallization may have produced the inverse trend.
The Distribution of Glacial Perturbation of Heat Flow in Canada
Authors: Jessop Alan M.
Published: April 2011

A contour map has been constructed of the perturbation of heat flow caused by the Wisconsin and earlier glaciations of the Pleistocene period. Under extreme conditions perturbation can be as high as one-third of the world average heat flow, but in most areas the disturbance is of the order of 10% or less of the average heat flow.
Magnetic Anomalies over British Columbia and the Adjacent Pacific Ocean
Authors: Haines G. V. , Hannaford W. , Riddihough R. P.
Published: April 2011

A contoured residual map of the vertical magnetic field, observed at approximately 5 km altitude above sea level, provides a broad view of the major structures of the buried Canadian Shield, the Cordilleran Region, and the northeast Pacific Ocean.
Lead Isotope Studies of Rock Samples from the Superior Geological Province
Authors: Ozard J. M. , Russell R. D.
Published: April 2011

Single filament whole rock lead isotope analyses were corrected for fractionation by using an internal standard (double spike). An estimated standard deviation of 0.15% was obtained for lead isotope ratios and 0.25% for lead and uranium concentrations. These are some of the first analyses of this accuracy for lead isotopes in whole rocks. Lead and uranium analyses from the Vogt–Hobbs area near Lake Timagami, Ontario and from the Rice Lake – Beresford Lake area, Manitoba gave ages with the pattern lead–lead age > uranium 235 – lead 207 age > uranium 238 – lead 206 age. This pattern was interpreted as arising from loss of lead from the systems studied. A similar three-stage history, marked by major events prior to 3000 m.y. ago and at approximately 2600 m.y. ago, fits both of these suites. This history is shown to be consistent with rubidium–strontium data, zircon uranium–lead ages, potassium–argon, and ore lead data.
The Solubility of Water in Melts in the System NaAlSi3O8 – NaAlSiO4 – H2O
Authors: Kim Ki-Tae , Burley B. J.
Published: April 2011

The solubility of water in melts in the system NaAlSi3O8 – NaAlSiO4 – H2O has been determined up to 10 kb, essentially using the method of Kennedy et al. (1962). Because the gels used were extremely hygroscopic, however, a correction to the approximate solubility value obtained was made by determining the amount of moisture originally absorbed in the gel powders. Using this method, solubility data are simply obtained as by-products of the experimental runs made for the investigation of phase equilibria.The H2O-solubility in the melts is not too sensitive to a variation in anhydrous composition of the melts (~6 ± 1 wt.% H2O at 2 kb and ~11 ± 1 wt.% H2O at ~5 kb in the range of compositions Ab100Ne0 – An40Ne60). H2O-solubility in the (Anl) and (Ne) univariant melts was determined up to 10 kb (H2O contents: 4.7 wt.%/1.1 kb and 852 °C, 6.2 wt.%/2 kb and 804 °C, 10.8 wt.%/5.2 kb and 672 °C, 12.2 wt.%/6.6 kb and 655 °C, 13.2 wt.%/7.3 kb and 652 °C and 14 wt.%/10 kb and 632 °C). The origin of water bubbles in quenched hydrous glasses in this system is essentially attributed to the separation of the dissolved water from the melts upon quenching.This method was further extended to determine the H2O-content in hydrous minerals, analcite, nepheline hydrate I, and zeolite species P. encountered in this system. The results agree fairly well with data reported by previous authors.
Computerized Solutions for Some Problems of Fold Geometry
Authors: Nidd Eric , Ambrose J. W.
Published: April 2011

If the form of a fold is conical, important elements of its geometry are the attitude of its axis and the degree of conicity (i.e. the size of the semi-apical angle of the cone). (If the fold is cylindrical this angle is 0°; but as the semi-apical angle increases to 90° as a limit, the cone approaches a plane.) These elements of a conical fold can be calculated, given the attitudes of a number of planes tangential to the fold surface. Also the standard deviation of the observations from the ideal can be calculated and used to test the structural homogeneity of a given area. Previous solutions to this problem lead to ambiguous answers, as shown by C. S. Venkitasubramanyan (this issue).
Multiple Glaciation in Central British Columbia
Authors: Tipper Howard W.
Published: April 2011

During Fraser Glaciation central British Columbia was covered by glacier ice that accumulated in the Coast and Cariboo Mountains, flowed inwardly as a piedmont glacier to the Interior Plateau and thence northeasterly as an ice sheet toward the Rocky Mountains. After withdrawal of the Fraser ice sheet a limited re-advance of ice from Cariboo and Coast Mountains took place but not as a coalescent ice sheet. Drumlinoid forms, eskers, meltwater channels, kettled deposits, and lacustrine deposits provide ample evidence from which a glacial history of the area can be deduced. Although Fraser Glaciation is not believed to have culminated as an ice dome over central British Columbia, there is some evidence to suggest that earlier glaciations did form such a dome from which ice flowed radially over the Coast and Rocky Mountains.
Some Observations on the Formation of Wollastonite from Calcite and Quartz
Authors: Gordon T. M.
Published: April 2011

Mixtures of powdered calcite and quartz were reacted for various lengths of time at a total pressure of 2000 bars, 650 °C, in an H2O–CO2 fluid. Extent of formation of wollastonite was determined by partial chemical analysis of run products. Experimental scatter precludes detailed analysis of the reaction mechanism.The data show that approximately 40% reaction takes place in the first 24 h, and that after this initial period the rate decreases. Examination of run products shows the calcite to be surrounded by radiating wollastonite crystals. This suggests that the wollastonite cover forms during the initial stages of reaction and, by shielding the calcite, suppresses the reaction.Single cleavage flakes of calcite were packed in −325 mesh quartz and allowed to react under the same conditions as the powders. A scanning electron microscope was used to examine and photograph the fragment surfaces at the conclusion of the experiments.Examination of the photographs shows the calcite to be completely covered with a thin layer of wollastonite crystals. Details of the morphology suggest that the wollastonite grew outward from nucleation centers and that the solution of calcite and quartz may have been accelerated near growing wollastonite. Although no details of the reaction mechanism can be deduced, the model favored here is that growth was most rapid near the calcite–wollastonite interface and the mantling effect slowed the reaction by preventing the transport of silica to the calcite surface.
The Mid-Atlantic Ridge Near 45° N. XVII. Magnetic Anomalies and Ocean Floor Spreading
Authors: Loncarevic B. D. , Parker R. L.
Published: April 2011

In the North Atlantic it is difficult to correlate single magnetic profiles with the spreading ocean floor magnetic models. Within the area of intensive surveys at 45° N, it is possible to average the observations in the direction of the trend of the magnetic anomalies. The profile of averaged anomalies for all data between 45° N and 45.5° N correlates well with a magnetic model spreading (with respect to the ridge axes) westwards at 1.28 cm/y and eastwards at 1.10 cm/y, if the trend of the anomalies is assumed to be 015° East of North.
A Study of the Fe–Ti Oxides in the Whitestone Anorthosite, Dunchurch, Ontario
Authors: Kretchsmar Ulrich H. , McNutt Robert H.
Published: April 2011

The Fe–Ti oxides hemo-ilmenite, magnetite, and minor ferrian ilmenite occur predominantly in the foliated oxide-rich, garnet-bearing border facies of the Whitestone anorthosite. The rhombohedral phases comprises 80–90 modal % of the oxides, and shows variation in bulk composition from Ilm90Hem10 to Ilm50Hem50 (mol %), which we interpret to be a result of local variation in [Formula: see text]. Hemo-ilmenites with bulk compositions more ilmenite rich than approximately Ilm85Hem15 exsolve predominantly by a continuous exsolution mechanism, whereas more hematite rich phases exsolve discontinuously. Along the hematite limb of the solvus, the exsolution mechanism changes at a bulk composition of approximately Hem60Ilm40. The compositions of hematite lamellae and host phase ilmenite in hemo-ilmenite are constant at Hem72Ilm28 and Ilm95Hem5 respectively, as indicated by electron-probe analyses. This suggests that the position of the hematite–ilmenite solvus is at more ilmenite rich compositions than was determined by Carmichael (1961).Magnetite contains less than 3.5 mol % Usp, and the average unit cell dimension of 14 samples is 8.396 ± 0.004 Å. In hemo-ilmenite grains adjacent to magnetite, hematite lamellae thin and disappear leaving a zone up to 50 μ wide of homogeneous ferrian ilmenite (Ilm95Hem5). This ilmenite was added during cooling, as the result of oxidation of ülvospinel in magnetite. We envisage that oxides of the Whitestone anorthosite cooled slowly, from an initially high temperature stage in a tectonically quiet environment.
An Evaluation of Three Methods for the Quantitative Determination of Calcite and Dolomite in Soils and Geological Sediments
Authors: Zwarich M. A. , Mills J. G.
Published: April 2011

The manometric and two chemical methods, the NaOAc and H2SO4, were evaluated for the determination of calcite and dolomite in soils and geological materials and in the sand, silt, and clay fractions from these materials. The NaOAc acid buffer method was found to be comparable to the manometric method for the sand fraction and superior to the manometric method for analysis of the silt fraction. For the clay fraction, the manometric method was unsuitable but the NaOAc buffer method was satisfactory providing a slight correction was applied. The strong acid method was rejected as inaccurate. The NaOAc method is recommended for accurate analysis of total soils. Analysis of total soils by the manometric method was demonstrated to entail small but significant errors; the method is usable if these errors are acceptable.
Justification for Both Ionic and Thermal Reactions in Grenville Province Pelitic Rocks near Sudbury, Ontario, Canada
Authors: Kwak Teunis A. P.
Published: April 2011

Metamorphic reactions related to isograds derived from aluminum silicate-bearing pelitic schists were studied in an area of Grenville Province adjacent to Southern Province rocks near Sudbury, Ontario. Progressing from the northwest to southeast of the area, the meaningful hand-drawn isograds are: (1) sillimanite first occurrence, (2) the last occurrence of staurolite when associated with the entire assemblage, (3) K-feldspar first occurrence, (4) staurolite last occurrence as inclusions in garnet, (5) muscovite last occurrence, and (6) kyanite last occurrence. Whole-rock chemical analysis of 14 representative pelitic schist hand specimens in the area were collected and used to show that metamorphic factors, and not chemical differences, were responsible for the metamorphic isograds. The entire area lies thermally above the melting of rocks of granitic composition. Breakdown curves of the minerals related to the isograds have been used to imply a gradient of 670 °C to 750 °C and 6.3 to 7.3 kilobars, across the area, but the equations for these breakdowns are not entirely substantiated by the modal abundance and textural data.To a first approximation, the rocks may be considered homochemical, but many deviations (due partly to metasomatic change) from this exist. The ionic breakdown of kyanite to muscovite has been shown and an explanation as to why muscovite selectively replaces kyanite and not sillimanite is given. The breakdown of muscovite at the higher grades has been inferred to form K-feldspar, but not sillimanite. Near the kyanite isograd, textures showing the thermal breakdown of kyanite (left over after the partial ionic breakdown of the mineral) to sillimanite are shown. The rocks must have had at least K and possibly Fe added metasomatically to account for the textures shown. From generalized modal abundance surfaces (trend surface analysis), general equations representing the difference in modal abundance of minerals across various isograds were determined and from these, specific equations explaining the breakdown of a particular mineral at its isograd were derived. The most significant of these reactions is the first staurolite isograd, where it is inferred to breakdown in the following way, in the area studied:[Formula: see text]The dissolved Al and Si forms the fibrolite (sillimanite) lenses common in adjacent pelitic rocks
The Plum Point Interstadial: Age, Climate, and Subdivision
Authors: Mörner Nils-Axel
Published: April 2011

Plum Point Interstadial deposits in Scarborough Bluffs, Toronto, include a layer of unvarved sandy sediments, which indicates relative low lake level, with the ice margin some distance away, probably north of the Ontario basin proper. Radiocarbon dates above and below this layer suggest an age of the most temperate part of the Plum Point Interstadial of 32 000 – 28 300 B.P. i.e. exactly the same age as for the Denekamp Interstadial in Europe. The Plum Point Interstadial in a broad sense can be subdivided, climatically, into three units.
The Attikamagen–Ferriman Transition in Part of the Central Labrador Trough
Authors: Dimroth Erich
Published: April 2011

The sequence of the Labrador geosyncline is subdivided in three cycles, each beginning with deposition of shallow-water quartzites and precipitates and culminating with the deposition of thick shale–graywacke–basalt suites. This paper describes the stratigraphy and sedimentology of the formations deposited during the gradual re-stabilization of the basin at the end of cycle I.At the end of cycle I, red, green, and gray pro-deltaic shales and sandstones prograded into the basin from the west. They interfinger eastwards and upwards with the Dertaull Dolomite. In the west laminated dolomite was deposited on a deltaic platform; brecciated and conglomeratic dolomites developed at the slope margin, and grade into alternating laminated dolomite, conglomeratic dolomite, and pelite in the basin. Slumping and turbidity currents were important transport mechanisms. Lenses of massive dolomite deposited in relatively deep water occur in the center of the trough and a platform extended in the eastern, eugeosyclinal zone. Upper horizons of the Denault Dolomite grade into the Attikamagen IV basinwards. The basal member of the Attikamagen IV consists of relatively deep-water shales; these grade upwards into red silstone and fine-grained sandstones of deltaic or pro-deltaic origin. The Fleming Breccia overlies the Denault Dolomite at the western margin of the trough. This unit is probably derived from a bedded sequence of siltstone, sandstone, and dolomite, that has been profoundly altered by complete replacement of dolomite by chert, followed by pene-contemporaneous brecciation and slumping. The Wishart Formation overlaps all older units with a marginal unconformity, but has gradational contacts with the latest deposits of Cycle I (uppermost Attikamagen IV and perhaps Fleming) closer to the basin center.
Etching of the Test Surface of Benthonic Foraminifers due to Ingestion by the Gastropod Littorina littorea Linné
Authors: Walker D. A.
Published: April 2011

Investigations by scanning electron microscopy have revealed that ingestion of Rosalina floridana (Cushman) and Quinqueloculina seminulum (Linné) (Foraminiferida) by the common periwinkle Littorina littorea Linné results in severe etching of the surface veneer in the rotalids studied, and removal of the surface veneer and partial dissolution of the underlying tabular layer of calcite in the miliolids examined. The acidic nature of the digestive juices is suggested as the agent responsible for this phenomenon. Observations of test wall construction is compared to current models of calcite secretion.
Seismic Investigation of the Crater Lake Collapse Structure in Southeastern Saskatchewan
Authors: Gendzwill D. J. , Hajnal Z.
Published: April 2011

A detailed survey was carried out near Crater Lake, an unusual, circular depression 800 ft. (244 m) across, about 20 miles (~32 km) south of Yorkton, Saskatchewan. In-line and offset profiling with threefold subsurface coverage were used to outline this very small structure. The seismograms show a deep, narrow structural disturbance beneath the lake. This is interpreted as a chimney filled with breccia, which had collapsed into a solution cavern in the Prairie Evaporite salt over 3000 ft (914 m) below surface. About 125 ft (38 m) of salt has been removed from an area about 800 ft (244 m) in diameter. The chimney is about 350 ft (107 m) in mini mum diameter. Solution-collapse features are common in Saskatchewan, but previously none has been described that is so small or so well delineated on the surface. In northern Michigan, however, structures that are thought to be similar occur as columns of indurated breccia exposed by differential erosion.Small collapse structures present peculiar hazards to potash mining because they are very difficult to detect. There is also danger to roads and buildings should subsidence or sudden collapse occur in the future.
Remanent Magnetism of Lower Tertiary Lavas on Baffin Island
Authors: Deutsch E. R. , Kristjansson L. G. , May B. T.
Published: April 2011

Six horizontal basalt flows of presumed Paleocene age were sampled near Cape Dyer, Baffin Island. The natural remanence (NRM) is steeply inclined and nearly always of normal (+) polarity. NRM directions are generally very stable under alternating-field (AF) and thermal demagnetization. The average Koenigsberger ratio is about 10. Magnetic moment-temperature curves and microscopic examination indicate that the stable remanence resides in a single, primary titanomagnetite component, though Curie points are either 230–330 °C or 540–580 °C; the higher range represents a more advanced oxidation state and higher stability. Some anomalous samples having steep negative NRM's probably were remagnetized in a reversed geomagnetic field. Omitting these, a pole position based on five flow mean directions after AF treatment is 83° N, 55° W, with dp = 11½°, dm = 12°. This is broadly comparable with some of the published Lower Tertiary poles for the western United States. The results indicate that the basalts are excellent material for further paleomagnetic studies around Baffin Bay.
A Seismic Investigation of the Crust and Moho on a Line Perpendicular to the Grenville Front
Authors: Mereu R. F. , Jobidon G.
Published: April 2011

A major structural feature 50 to 75 km in width has been outlined along the Moho in an area just south of the Grenville Front from a delay-time analysis of Pn waves arriving from a number of different azimuths. The crust in this anomalous region was found to be from 5–10 km thicker than in the surrounding area. The low frequency portion of the gravity low in central Quebec can be attributed to this feature. The fact that the front is deep-seated suggests that it may mark the position of an ancient fault connected tectonically in origin to the mid-continent gravity high and Lake Superior syncline.During the summer of 1968, the University of Western Ontario participated with the Dominion Observatory of Canada and other research groups in a crustal survey of eastern Quebec. Shots of various sizes were fired by the Dominion Observatory at six different locations in central Quebec. Two of the locations were in the Superior (structural) Province, two in the Grenville (structural) Province, and two in the vicinity of the Grenville Front. The University of Western Ontario recording stations were located at distances from 60 to 800 km southwest of the shots and lay along (a) a 550-km long line running perpendicular to the Grenville Front from Lake Evans in the Superior Province to a point just south of Lake St. John in the Grenville Province, (b) a 100-km long line running parallel to the Grenville Front from Chibougamau to the northeastern end of Lake Mistassini. Six portable seismic recorders (two of them 3-component) were moved every day. A total of 45 locations were occupied, with observations being made in a fan-like manner.The apparent crust and upper mantle velocities as determined by a least squares analysis of all the data are 6.43 ±.03 km/s (43 observations) and 8.15 ±.03 km/s (70 observations) respectively. From an analysis involving combined seismic and gravitational observations along with synthetic seismograms, the following structure emerges. The mean velocity of the upper crust is 6.31 km/s, but because of the lateral variations in its structure the true velocity varies from 6.1 to 6.6 km/s, the higher values occurring just south of the Grenville Front. No clear evidence for layering could be found throughout the crust, but both seismic and gravitational observations indicated that the mean velocity of the lower portion of the crust was 6.55 km/s with this value increasing to at least 7 km/s just above the Moho. The apparent velocities of smaller regional samples of Pn observations varied erratically as a result of topography on the Moho. However values obtained from arrays oriented parallel to the Grenville Front were significantly higher, indicating that the upper mantle may be behaving in an anisotropic manner.
The Use of Negative Feedback with Astatic Magnetometers for Paleomagnetic Studies
Authors: Roy J. L.
Published: April 2011

Both the performance and efficiency of an astatic magnetometer have been greatly improved by using a negative feedback system. The magnetometer has been converted into a multisensitivity instrument. A much accelerated response time permits one to measure directly the directions (declination and inclination) and intensity of magnetization of a rock specimen rather than computing them from the measurement of three orthogonal components. A greater sensitivity permits one to measure intensities ten times smaller than was possible without negative feedback. The instrument can be switched through eleven steps from a sensitivity of 0.56 × 10−9 Oe/mv and a period of 5.1 s down to a sensitivity of 1.2 × 10−7 Oe/mv and a period of 1.2 s. This permits the measurement of rock specimens magnetized to an intensity as high as 5 × 10−3 emu and as low as 1 × 10−7 emu. On an average, twelve specimens are measured in one hour.