bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron microprobe study of magnesium distribution in some Mississippian echinoderm limestones from western Canada
Authors: Macqueen R. W. , Ghent E. D.
Published: April 2011

Electron microprobe techniques were used to examine the distribution of Mg, Ca, and Fe in six samples of Mississippian skeletal and oölitic limestones from the Alberta Rocky Mountains. All samples show extremely low values of Fe. The following distributions of Mg (in wt % MgCO3) were observed: in four samples from the Loomis Member (Meramec) of the Mount Head Formation, echinoderm grains show highly variable Mg content averaging 1.11–1.43, whereas sparry calcite cement and the outer rings of oöids show much more uniform values averaging 0.73–0.84. In one sample from the Livingstone Formation (Osage), echinoderm grains show large Mg variation with a mean of 0.95; sparry calcite cement shows more uniform values with a mean of 0.50. A second, highly recrystallized sample from the Livingstone Formation has echinoderm grains which show large Mg variation with a mean of 0.43. The stroma canal structure characteristic of living echinoderms is not generally preserved in the grains. All of the echinoderm grains analyzed contain abundant dolomite crystals 1 to 6 μ in diameter which appear to account for the variable values of Mg distribution, but are not obviously related to the original stroma canal structure. Sparry calcite cements and oöid rings are free of dolomite crystals. The small size of the dolomite crystals, combined with their widespread distribution within and restriction to echinoderm grains, suggests an exsolution origin. Exsolution is suggested to have taken place subsequent to a) loss of most of the Mg from the original magnesium-rich echinoderm calcite, and b) precipitation of pore-filling calcite within the echinoderm grains. The minute dolomite crystals are thus interpreted as representing a late stage exsolution product of small residual amounts of Mg from both the original grains and their pore-filling calcite.
A Pleistocene muskox (Ovibos moschatus) from gravels of Illinoian age near Nome, Alaska
Authors: Harington C. R.
Published: April 2011

A muskox cranial fragment from outwash gravels of Illinoian age near Nome, Alaska is referable to Ovibos moschatus, which survives in arctic Canada and Greenland. The specimen is evidence suggesting that O. moschatus first entered North America from Eurasia across a land connection during the penultimate (Illinoian) glaciation.
Evidence of glacial readvance over soft-layered sediments near Kingston, Ontario
Authors: Sangrey D. A.
Published: April 2011

A study of the soils in four filled valleys has defined two distinctly different sequences. The upper soil at all sites is a soft, horizontally layered or varved clay. Underlying these soils are stiff, overconsolidated deposits which appear to have been layered or varved clay but are now highly faulted and distorted; their low water content, overconsolidation, and structural distortion indicate glacial overriding.Measurements of preconsolidation stresses of these lower deposits provide data for calculations of overriding ice thickness and surface elevation of the ice. A consistent pattern was found from analysis of four widely separated boreholes. Surficial landforms and topography support the conclusion that parts of the area were overridden by ice.Engineering soil mechanics tests not normally used in geological interpretation are an important part of this analysis.
Ferromanganese concretions in Lake Ontario
Authors: Cronan D. S. , Thomas R. L.
Published: April 2011

A large deposit of ferromanganese oxide concretions has been found in the northern portion of Lake Ontario. The concretions occur mainly in the form of coatings on sand grains but manganese nodules are present at several localities. Mineralogically, the ferromanganese oxide phases are amorphous, and their Fe and Mn contents are similar to those in concretions from other environments. However, their Ni, Co, and Cu contents are significantly higher than those reported in previously described North American lacustrine ferromanganese concretions, and this may, in part, be a reflection of their probable low rates of accumulation.
Rb–Sr Geochronology of the Hida metamorphic belt, Japan
Authors: Shibata K. , Nozawa T. , Wanless R. K.
Published: April 2011

Rb–Sr whole-rock and mineral isochron ages have been determined for metamorphic and granitic rocks of the Hida metamorphic belt. The results indicate that an extensive metamorphic event together with plutonic activity took place within the belt during the latest Paleozoic – early Mesozoic period. The older ages of 220–250 m.y. represent an earlier phase of the metamorphism, whereas the younger ages of 170–180 m.y. represent a later phase. The Funatsu granitic rocks yielded a whole-rock isochron age of 176 m.y. with an initial 87Sr/86Sr ratio of 0.7056. This age is believed to indicate the time of original emplacement, and the rocks are considered to represent late-kinematic intrusion in the Hida belt.Some information on the middle Paleozoic metamorphism in the Hida Mountains was obtained from the isochron study. The whole-rock isochron age of 412 m.y. for the metamorphic rocks of the Fujibashi area may be considered, although not confirmed, to indicate the time of older metamorphism. The Omi Schist of the Circum–Hida crystalline schist belt, which belongs to the glaucophanitic type of metamorphism, gave a mineral isochron age of 350 m.y. thereby providing evidence of mid-Paleozoic metamorphism.The initial 87Sr/88Sr ratios for the whole-rock samples of the Hida metamorphic belt are found to be generally low, i.e. 0.705–0.708. This is especially so for the metamorphic rocks from the northern part of the belt where the lowest values were found.
Application of association–analysis to distribution studies of Recent Foraminifera
Authors: Vilks G. , Anthony E. H. , Williams W. T.
Published: April 2011

Counts of species of foraminifera from 75 samples of sediment from East Bay, MacKeazie King Island, in the Canadian Arctic were converted to a matrix of presence–absence data (56 species × 75 stations). These were submitted to both normal and inverse association–analysis as a preliminary test of the application of that multivariate method to problems in marine ecology. The results are compared with observations made at the time the survey was carried out. Although the pattern of sampling was not the most suitable for association–analysis, the results indicate that the method may prove quite informative.
Petrochemistry of volcanic rocks of the Harbour Main Group, Avalon Peninsula, Newfoundland
Authors: Papezik V. S.
Published: April 2011

The predominantly volcanic Harbour Main Group of Proterozoic (Hadrynian) age forms a northerly-trending belt in the central part of the Avalon Peninsula, Newfoundland. The rocks include flows, pyroclastics, and several belts of well-preserved ignimbrites.Twenty-two recent chemical analyses of volcanic rocks, sixteen of them not previously published, show that the Harbour Main volcanic suite is distinctly sodic and weakly alkalic, ranging from basic rocks of the hawaiite–mugearite type to sodic rhyolites with relatively high alkali content; the alkali-lime index of the suite is 52.The Harbour Main rocks are shown to be chemically similar to the Late Precambrian Uriconian volcanic suite in Central Britain, with which it has been previously tentatively correlated on other grounds. It is suggested that the volcanic rocks of the Avalon Peninsula and the British Midlands were formed in different parts of a possibly continuous tectonic belt in a period of post-orogenic block-faulting of the Basin and Range type, prior to the opening of the present Atlantic Ocean.
The Mid-Atlantic Ridge at 45° N. XIV. Oxidation and magnetic properties of basalt; review and discussion
Authors: Irving E.
Published: April 2011

The magnetic properties of submarine basalt procured in a traverse across the accreting margin of a lithospheric plate are reviewed. These properties are attributed to two processes. Firstly, the rapid quenching of lava in the axial zone of accretion produces dispersed titanomagnetite of very small grain-size, ranging from about 5 μm down to submicroscopic sizes. During quenching the pillow lava acquires a very intense (0.1 c.g.s. units per cm3) and stable (mean coercivity of remanence 240 Oe) remanent magnetization, with Q of the order 100. The oxidation state is initially low (FeO/Fe2O3 averages about 7) but, presumably because of rapid quenching, it is chemically unstable, and undergoes secondary oxidation, so that at a distance of 10 km in from the accreting margin the FeO/FenO3 ratio has fallen to about unity, the remanence has decreased by a factor 10, and the Curie and blocking temperatures have risen from the range 100–300 °C to the range 300–500 °C. It is suggested that these magnetic changes are caused by very mild hydrothermal activity in the axial zone of accretion. The larger magnitude of the axial geomagnetic anomaly compared with those immediately to each side (a difference of a factor 2 over the Mid-Atlantic Ridge) is attributed to this oxidation process.These magnetic properties are very different from those of basic intrusive and subaerial igneous rocks which characterize the early (that is continental) rifting stages of ocean formation. This is because the grain sizes of their titanomagnetites are larger, commonly ranging beyond 50 μm, which is due to their taking years or decades to cool, rather than the minutes or hours, required by water-quenched basalts. Large grains have a much smaller specific intensity than small grains, so that the remanence of dolerite is generally less than that of submarine lava, and Q is of the order unity. Consequently, in the continental rifting stages, igneous rocks which, by-and-large, are incapable of causing very large anomalies in the geomagnetic field are produced, and this, it is argued, may be the origin of the magnetically smooth zones which border the North Atlantic, which occupy all except the central deep of the Red Sea, and which also may be represented in the inner basins of the Gulf of California.Because of quenching and low initial oxidation state, sulfide minerals are generally present in submarine basalts which therefore may be a potent source of sulfide mineralization.
Chloride and bromide in carbonate rocks in relation to the chemical history of ocean water
Authors: Williams Harold H. , Harriss Robert C.
Published: April 2011

The acid soluble chloride/bromide ratios of 66 limestones and 74 dolomites and the water soluble chloride/bromide ratios of 65 limestones and 42 dolomites were determined for samples from Recent to Precambrian age (2 b.y.). A progressive increase occurs in the chloride/bromide ratio from the Precambrian to Recent and is interpreted as representing an increase in the chloride/bromide ratio of sea water over the past 2 × 109 years. It is postulated that removal of bromine from sea water by sedimentation of bromine-enriched organic matter and crustal recycling of sedimentary rocks is responsible for the increase in the chloride/bromide ratio of sea water.
A Seismic Refraction Profile Across the Polar Continental Shelf of the Queen Elizabeth Islands
Authors: Berry M. J. , Barr K. G.
Published: April 2011

During the spring of 1967, a seismic refraction experiment was conducted from the SW tip of Prince Patrick Island in the Queen Elizabeth Islands of Arctic Canada to a point mid-way down the continental slope, some 220 km from the coast.It was found that seismic recording on sea ice was plagued by unusually high background noise levels which could be attributed to low frequency (below 1 Hz) oscillations of the ice pans and to the broad-band noise generated by frequent ice cracking. It was discovered, and is shown theoretically, that seismic wave propagating through a water layer (the ocean) and incident on the ice layer from below provide an exact π/2 phase shift between the horizontal and vertical components of surface motion. This fact can be used to advantage in digital processing.The interpretation shows a crustal model with depths to the M discontinuity of 28 ± 4 km at the coast, thinning to 15 ± 9 km at the end of the profile. The velocity of the mantle is measured as 8.05 ± 0.17 km/s. Mid-way down the continental slope there are 5.0 ± 1.63 km of sediments overlying material with a velocity of 5.36 ± 0.15 km/s. Material of a similar velocity, 5.72 ± 0.18 km/s, lies 2.7 ± 1.9 km beneath the surface material at the coast, where the surface layer has a velocity of 4.76 ± 0.4 km/s. It is concluded that the data support the hypothesis that the Canada Basin has an oceanic rather than a continental crust.
The Origin of Massive Icy Beds in Permafrost, Western Arctic Coast, Canada
Authors: Mackay J. Ross
Published: April 2011

Massive beds of ground ice are shown to exist along the arctic coastal plain east of the Alaska–Yukon boundary for a distance of at least 500 km. The massive ground ice can be seen in both undisturbed and glacially disturbed Pleistocene sediments. An examination of several thousand seismic shot hole logs, from drill holes of 15 to 35 m in depth, also corroborates the widespread occurrence of ground ice. The icy beds typically have an ice content, defined in terms of the weight of ice to dry soil, in excess of 200% for sections as much as 35 m thick. A theory is presented which suggests that: the ice is of segregation origin; the source of excess water was from the expulsion of ground water during the freezing of sands; and high pore water pressures, favorable to ice segregation, developed beneath an aggrading impermeable permafrost cover. Permafrost aggradation may have occurred either on an exposed sea floor during a period of sea level lowering which would have accompanied a glacier advance, or following a warm interval in which there had been deep thaw. Similarities in the origin of pingo ice and massive ice are discussed.
Characteristics of Limestone Solution in the Southern Rocky Mountains and Selkirk Mountains, Alberta and British Columbia
Authors: Ford D. C.
Published: April 2011

The temperature, pH, and carbonate hardness of 415 water samples were determined in four limestone areas in the southern Rocky Mountains and Selkirk Mountains of Canada. Sampling covered all of the major carbonate rock formations of the region, ranged across the floral lifezones and included surface and sub-surface examples. In the forest zone at Crowsnest Pass, solute concentration in a major karst spring was inversely proportional to discharge; solute concentrations in a nearby creek and lake showed little variation with discharge. In tundra and alpine desert zones at Mt. Castleguard, solute concentrations were lower than in the forest, and marked depletion of PCO2 was indicated in some restricted cases. In the Maligne River basin, limestone forest and tundra waters were again contrasted. Solute concentrations in the trunk river and in lakes and underground channels along its course were determined by the mixing of karst and non-karst waters. At the Nakimu Caves there is a strong contrast between limestone seepage waters and allogenic streams.Karst waters of the region are classified as follows:(A) Above treeline: (i) tundra and some turbid glacial meltwaters—saturating with respect to calcite in the range 50–90 ppm CaCO3; (ii) snowmelt and some clear glacial meltwaters contacting bare limestone only—saturating with respect to calcite with <50 ppm CaCO3.(B) Below treeline: (i) holokarst groundwaters—saturating with 100–265 + ppm CaCO3; (ii) holokarst creek and lake waters—saturating with 100–140 ppm CaCO3; (iii) mixed waters from karst and non-karst terrains—with 35–90 ppm CaCO3.The forest waters compare with those from temperate and tropical forested karsts and indicate CO2 enrichment from soil air sources. The tundra waters are similar to those of the Alps and of an arctic tundra. Certain large cave streams remain very aggressive w.r.t. calcite after lengthy and rough passages through limestone. The ratio CaCO3:MgCO3 in most of the karst waters is close to 2.5:1.
The Origin of Sheet Fractures in the Galore Creek Copper Deposits, British Columbia
Authors: Allen Donald G.
Published: April 2011

A surface feature characteristic of the Galore Creek copper deposits is a set of well-developed closely-spaced fractures, termed sheet fractures. The formation of these fractures is attributed to the widespread presence of anhydrite, a hydrothermal alteration mineral associated with copper. The fractures apparently developed as a consequence of the volume increase due to hydration of the anhydrite to gypsum by meteoric water.The Galore Creek deposits have many characteristics of porphyry copper deposits, in many of which anhydrite or gypsum has been reported. Anhydrite may be responsible for the development of sheet fractures elsewhere.
Pedogenesis of the Precambrian Rocks in the Hanson Lake Area, East-Central Saskatchewan
Authors: Gaskarth J. W.
Published: April 2011

Precambrian rocks in the Hanson Lake area occur in two main groups. The first (Lower Group) consists of quartz dioritic rocks, migmatites, and agmatites which occur in two large anticlinal complexes. These rocks are overlain by and concordant with a complicated sequence of supracrustal rocks which comprise the second group (Upper Group). The basal part of the Upper Group is basaltic and the rest is made up of basaltic, andesitic, dacitic, and rhyolitic fragmental metavolcanic rocks, dacitic metalavas, calc-silicate rocks, and graywacke-type metasediments. Other rocks in the area include several bodies of intrusive granite, one of which has a mass of magnetite – amphibole – epidote rock associated with it, a body of metapyroxenite, and a number of apparently intrusive amphobolite bodies. Both beryliferous and non-beryliferous pegmatites are abundant and occur mainly within the rocks of the Lower Group.An interpretation of the petrogenesis, consistent with the available petrographic, structural, and chemical evidence (46 new chemical analyses are presented), suggests that the Upper and Lower Groups were originally parts of a conformable supracrustal sequence. The lower parts of the sequence (Lower Group) were migmatized, partially melted, and mobilized during a complicated orogenic cycle.
Early Campanian Multituberculates (Mammalia: Allotheria) from the Upper Milk River Formation, Alberta
Authors: Fox Richard C.
Published: April 2011

Mammalian teeth collected from the early Campanian Upper Milk River Formation, southernmost Alberta, document a hitherto unknown evolutionary radiation of Late Cretaceous ptilodontoid and taeniolabidoid multituberculates. New species of the ectypodontids Mesodma and Cimexomys, the ptilodontid Cimolodon, and the cimolomyid Meniscoessus are defined, and teeth possibly pertaining to a second species of Mesodma and two species of Cimolomys are described. A new genus and species with uncertain relationships to known multituberculate families, is tentatively classified in the Taeniolabidoidea. Among North American Late Cretaceous multituberculates, at least Mesodma, Cimexomys, Cimolodon, Cimolomys, and Meniscoessus are seen to be evolutionarily conservative during early Campanian to late Maestrichtian times. The effects of sampling error on relative taxonomic diversity at horizons in the North American Upper Cretaceous are discussed.
Apparent Resistivity Calculations for Three Two-dimensional Conductivity Models with Vertical Discontinuities
Authors: Jones F. W.
Published: April 2011

Electromagnetic induction in three two-dimensional models of conductors with two regions of different conductivity is considered. Solutions are obtained for both the H-polarization and E-polarization cases by a numerical method. Apparent resistivity as a function of period is plotted for various locations relative to the surface contact. For the H-polarization case, the apparent resistivity values calculated for points near the surface contact are affected by the varying surface charge on the interface between the regions, and a value different from the expected value is obtained. In the E-polarization case the apparent resistivity curves exhibit a "dip" characteristic when the apparent resistivity is calculated for surface points near a shelf or step structure. In both cases the value of apparent resistivity calculated at or near surface contacts between different conducting regions depends greatly on the sub-surface structure.
Sediments and Bed Forms on a Braided Outwash Plain
Authors: McDonald Barrie C. , Banerjee Indranil
Published: April 2011

Sediments and bed forms from three braided outwash plains and one steep non-braided mountain stream in the Rocky Mountains of Alberta are compared to sediments and structures exposed in a paleo-outwash sequence.Channel sediments are subdivided into (a) pool facies: ripple- and parallel-laminated silty sand, with current crescents around isolated stones; and (b) riffle facies: parallel-stratified gravel and silt or silty sand.'Transverse ribs' constitute a bed form typical of riffle portions of channels. This bed form occurs as a train of regularly spaced pebble, cobble, or boulder ridges oriented transversely to the flow. Locally, the pebbly ribs are separated by, and rest on, a stone-free silty substratum. It is suggested that transverse ribs constitute a common equilibrium bed form in higher gradient riffle portions of gravelly alluvium.Longitudinal bars dominate interchannel areas of the modern outwash plains. They consist of coarse, poorly sorted gravel, either massive or exhibiting crude horizontal stratification. The paleo-outwash, composed of finer-grained and better sorted gravel, is characterized by sets 5 to 30 cm thick of cross-stratified sand and by sets 75 to 82 cm thick of cross-bedded pebble gravel. These may be related to progradation of dunes and bars, respectively.Standard deviations of channel azimuths in modern outwash plains are appreciably less than that recorded by cross-stratification measurements in the time-transgressive sequence of paleo-outwash. This is partly due to the braided system of channels having swept from side to side across the plain through time.
Early Cambrian and Older Trace Fossils from the Southern Cordillera of Canada
Authors: Young F. G.
Published: April 2011

Metazoan trace fossils of Early Cambrian and older age have been found in parts of the Gog, Cariboo, and Miette Groups of eastern British Columbia and western Alberta. Most of them occur in beds immediately below the zones containing the earliest Cambrian trilobites and archaeocyathids. These beds represent a variety of sedimentary environments, including the beach and littoral (Skolithos – facies), and shallow marine (Cruziana – facies) environments in the upper McNaughton Formation of the Gog Group: and a moderately deep marine environment in the Midas Formation of the Cariboo Group. Below these zones evidence of organic life is mainly restricted to stromatolites in carbonate rocks, and simple feeding-burrows in argillaceous silt-stones. A rare, but important trace fossil in this zone is a doubly furrowed trail, which is herein named Didymaulichnus miettensis (gen. et sp. nov.). This fossil indicates that metazoans existed before the Cambrian Period by a span of time represented by the net deposition of up to 2000 m of detrital sediments.
The Origin of the Apsley Gneiss, Ontario
Authors: Shaw Denis M.
Published: April 2011

The Precambrian Apsley gneiss forms part of the Grenville Series, outcropping mainly in Chandos Township in southeastern Ontario. The principal member is a biotite-microcline-oligoclase-quartz rock. Its original premetamorphic nature cannot be determined by geological criteria: the most likely protoliths are silicic volcanics or sandstones.Analyses of 49 specimens are compared in various ways with large numbers of igneous and sedimentary rocks of similar ranges in bulk composition. Two-variate scatter diagrams proposed by Köhler and Raaz, by Weisbrod, and by Moine and de la Roche permit identification of sedimentary parentage in favorable cases. Discriminatory analysis is better, and the following function (wt. % values) is recommended for rocks of this kind:[Formula: see text]Positive values of DF indicate probable igneous parentage; negative values are sedimentary. Discriminant functions including trace elements cannot be adequately appraised until more data are available for ordinary sedimentary rocks.The Apsley biotite gneiss is probably a series of interstratified silicic volcanics (about 60%) and sandstones.
Cenozoic and Mesozoic Stratigraphy of the Nova Scotia Shelf
Authors: McIver N. L.
Published: April 2011

Cenozoic–Mesozoic stratigraphy of the Nova Scotia shelf has been subdivided into three groups, twelve formations, and four members on the basis of subsurface information from approximately twenty offshore wells. The oldest stratigraphic unit recognized is salt, possibly of Early Jurassic age. The salt occurs in several sub-basins, where it is generally overlain by a conformable sequence of dolomite, anhydrite, limestone, and shale. Poorly sorted, feldspathic, clastic sediments disconformably overlie the evaporite sediments and adjacent basement rocks composed of metasediments and granite.The Western Bank Group consists of limestones and associated shales, which were deposited during widespread marine transgression. Marine sediments are in turn overlain by, and in part equivalent to, several thousand feet of Jurassic and Cretaceous sandstones and shales of the Nova Scotia Group. Sand deposition gradually waned in late Cretaceous time and the shelf was completely submerged. The overlying Gully Group of shales, thin limestones, chalk, and argillaceous sands was deposited in water depths ranging from bathyal to neritic. The Cenozoic section was finally truncated during a pre-glacial period of erosion.
The Palatal Structure of some Canadian Hadrosauridae (Reptilia: Ornithischia)
Authors: Heaton M. J.
Published: April 2011

Two distinct hadrosaurian lineages can be delineated, each showing changes from possible hypsilophodont ancestors. The Hadrosaurinae are typified by moderately vaulted palates, broad pterygoid flanges, large anterior maxillary processes, and non-folded premaxillae, with direct narial passages. The Lambeosaurinae are characterized by highly vaulted palates, narrow pterygoid flanges, reduced anterior maxillary processes, and folded premaxillae and nasals with looped narial passages.Reconstruction of the palate indicates that the internal nares were displaced rearward, thus producing a structure similar to the secondary palate of mammals.The Constrictor Dorsalis group-muscles were well developed, allowing some minor lateral movement of the palate by slight torsion of the pterygoid. The large pterygoid flange would have prevented fore-and-aft movement of the palate.A reappraisal of the relationships between the lambeosaurine crests and the respiratory system indicates that the crests may have been used in developing individually recognizable calls. Previously unrecognized behavioural relationships may have been typical of these possibly endothermic animals.
An Occurrence of Archean Pseudotachylite from Southeastern Manitoba
Authors: Ermanovics I. F. , Helmstaedt H. , Plant A. G.
Published: April 2011

Zoned veins (glass and crushed rock) of pseudotachylite occur in an Archean mylonite near Charron Lake, Manitoba. Glass occupies the centers of some veins and fusion products penetrate symmetrically distributed, crushed rock zones. The emplacement of the pseudotachylite postdates the formation of the mylonite fabric, but a later deformation affected both pseudotachylite and mylonite. The average chemical composition of the pseudotachylite veins reflects the composition of the host rocks, although the opaque, marginal crushed rock zones are enriched in iron and the fused centers are depleted in sodium. Glass is confined to crushed rock veins although not all crushed rock veins contain glass; apparently an increase in water pressure led to fusion.
Structure et Propriétés Physiques de l'Écorce Terrestre en Fenno-Scandinavie
Authors: Seguin Maurice K.
Published: April 2011

The author completely reviews previous geophysical work related to the nature and structure of the earth's crust in Fennoscandia. He explains the analytical procedure used for the seismic data and the method used to locate seismic events in Fennoscandia. Having described the method of analysis, the procedure for the calculation of the velocity of the seismic waves, and the location of seismic events which originate from Fennoscandia as well as the characteristics of the seismic waves registered, the author calculates the thickness of 3 layers which constitute the earth's crust at various localities in Fennoscandia and drafts a spatial distribution for the thickness of each of these layers. The first order variations, which agree with the relative thickness of the layers, indicate the presence of a generally east-west gradient. A general thinning of the crust was observed to the west in Fennoscandia. In view of the results obtained, the author draws conclusions relative to the tectonic activity and the global geodynamics in Fennoscandia.
Ostrich Dinosaurs from the Late Cretaceous of Western Canada
Authors: Russell Dale A.
Published: April 2011

The family Ornithomimidae is defined on the basis of the skeletal morphology of the three genera Ornithomimus, Struthiomimus, and Dromiceiomimus known in continental strata in Alberta, which are temporally equivalent to the Upper Campanian substage. At least two genera occur in Canadian Lance (Upper Maestrichtian) equivalent strata, but cannot be identified at present. A group of more primitive ornithomimoid theropods is represented else-where by the late Jurassic Elaphrosaurus and early Cretaceous Archaeornithomimus.Ornithomimid attributes include a general body form which parallels that of the ratites; elongate forelimbs, a kinetic skull, enormous eyes, a relatively highly evolved brain, and possibly a secondary palate and supertemporal fenestrae which were nearly encircled by alae of the squamosal. A reconstruction of the myology of the thigh indicates that ornithomimids were extremely fleet, but lacked the agility characteristic of modern large ground birds. They probably subsisted on small, soft-bodied animals.
The Canadian Cordillera, the Hellenides, and the Sea-Floor Spreading Theory
Authors: Dercourt Jean
Published: April 2011

The theory of plate tectonics is applied to the tectonic evolution of the Hellenides and the Canadian Cordillera. In the Hellenides a Tethyan zone of sea-floor spreading developed within the continental crust during Triassic time and functioned until the end of the Middle Jurassic. It led to the formation of two plates, each with continental and oceanic segments, that were separated in some places by accreting plate margins and in others by transform faults. In Late Jurassic time the mid-Tethyan ridge became inactive as new ridges developed in the Atlantic Ocean. From Late Jurassic to Recent time, Tethyan oceanic crust largely disappeared under one of the cratons. The chronology of tectonic events in the Hellenides corresponds well with that of sea-floor spreading in the Atlantic.Four periods of sea-floor spreading were involved in the formation of the Canadian Cordillera: (1) a Silurian? to Early Devonian period when an Archeo-Pacific Ocean separated the Canadian craton with a stable sedimentary margin from a volcanic archipelago; (2) a Middle Devonian to Permian period when the extinct volcanic archipelago was bounded to the west by a spreading Paleo-Pacific Ocean, and to the east by a tectonic contact which was consuming Archeo-Pacific oceanic crust; part of this crust was obducted over the continental margin; (3) a Late Triassic to Middle Jurassic period when a second volcanic archipelago separated a spreading Neo-Pacific Ocean from the continental margin; and (4) a Late Jurassic to Recent period where spreading occurred in both the Atlantic and Pacific Oceans, subjecting the second volcanic archipelago and the continental margin to major tectonism; since the Paleocene, the Cordillera has slid towards the NNW along transform faults.
Geomorphological Development and Post-Pleistocene Sea Level Changes, Northumberland Strait, Maritime Provinces
Authors: Kranck Kate
Published: April 2011

Radiocarbon dates, continuous seismic reflection lines, echograms, bottom sediments, and surface topography are used to establish the geomorphological development and post-Pleistocene sea level changes in Northumberland Strait. The oldest recognizable topography is a pre-Pleistocene drainage system eroded into the bedrock. During the post-Pleistocene marine transgression four terraces were formed. Their ages and spatial distribution reflect the combined effect of postglacial sea level changes and crustal movement. After glacial withdrawal the strait was occupied by two estuaries separated by an isthmus. In the west, the sea initially covered much of the present land which had not yet recovered from glacial depression. Between about 13 000 and 7000 years B.P. glacial rebound caused temporary regression of the shoreline until rise in sea level again became the dominant force. In the east, rise in sea level always kept pace with any rebound, and has gradually enlarged and deepened the submerged area. Northumberland Strait became a continuous body of water about 5000 years B.P. when the isthmus to Prince Edward Island was breached. Comparison with sea level curves from other areas of the world indicate that Northumberland Strait has been subsiding during the last 7000 years. The rate of subsidence appears to have been greater in the western part of the strait than in the eastern. It is suggested that this part of the Maritime Provinces lies between areas of positive and negative crustal movement.
Tectonic Overprinting near Ware, Northern Rocky Mountain Trench
Authors: Eisbacher G. H.
Published: April 2011

Mapping in the core of the north–central Cordillera of British Columbia has revealed a system of relatively closely spaced steeply dipping faults cutting across an earlier penetrative fabric consisting of recumbent folds and intensely cleaved sedimentary rocks. The earlier (Mid – Late Jurassic) penetrative deformation was separated from the later (Late Cretaceous – Tertiary) deformation by regional uplift, normal faulting, and initiation of intermontane deposition. The Upper Cretaceous – Lower Tertiary Sifton Formation was involved only in the later deformational pulse. Kink folding and oblique faulting are the principal mechanisms of the later pulse. The orientation of principal regional contraction changed from an early WSW–ENE direction to a late SSW–NNE direction. From this it is inferred that some of the young lineaments along and near the Rocky Mountain Trench are probably oblique–slip faults with unknown, but probably small right–lateral slip components.
A Possible Time Span for the Late Precambrian of the Avalon Peninsula, Southeastern Newfoundland in the Light of Worldwide Correlation of Fossils, Tillites, and Rock Units within the Succession
Authors: Anderson M. M.
Published: April 2011

Since too few absolute age determinations have been carried out on late Precambrian rocks of the Avalon Peninsula, southeastern Newfoundland, a stratigraphic approach has been adopted to obtain the necessary dates on which to base a possible time-span for the whole succession. The correlatable 'features' of the Avalon Peninsula late Precambrian—fossils, tillites, and volcanic episodes, have been correlated with similar 'features' in late Precambrian sequences in other parts of the world where these 'features' have been dated isotopically. Some of the correlations are probable, others only possible as long-distance correlation involves an element of speculation.Conception Group sedimentation may have lasted from 710 m.y. ago, the possible age of the 'basal' conglomerate, to ca 600 m.y. ago, and possible ages for the Conception Group tillites and fossils (Mistaken Point fauna) are 670–715 m.y. and 610 to 630 m.y. respectively. Harbour Main volcanism began some 795 m.y. ago and continued until about 715 m.y. before present. These ages indicate a possible age-range for the late Precambrian of the Avalon Peninsula from ca 800 m.y. to 570 m.y. (age of base of Cambrian accepted here), a time span of ca 230 m.y. that is equivalent to the greater part of the Proterozoic Hadrynian Era.The soft-bodied metazoan fossils of the Conception Group Mistaken Point fauna are comparable to those of the Australian Ediacara fauna and related forms in other parts of the world. Conception Group tillites are correlated with glaciogenic deposits of the uppermost Precambrian ice age in central Australia, the Rybachiy Peninsula, U.S.S.R., and Scotland (Dalradian tillites). Harbour Main Group volcanics are correlated with part of the Coldbrook Group volcanic sequence, southern New Brunswick; the Fourchu Group and Morrison River Formation of southeast Cape Breton Island are believed younger, and possibly, the time equivalent of the upper part of the Musgravetown Group together with the Random Formation, western Avalon, although the possibility of the Morrison River Formation being Cambrian cannot be excluded. Correlation of Harbour Main volcanics with volcanics of late Precambrian age in the British Midlands is considered a possibility but remains conjectural.A single intrusive event is favored for emplacement of the Holyrood granite 607 ± 11 m.y. ago. This necessitates there having been older granite in the area to provide a source for the granite clasts in the Conception Group conglomerates and tillites. A second, less likely, alternative is that the Holyrood granite was emplaced over a substantial period by successive pulses of magma; the 607 m.y. age is then that of the last intrusion of magma.
Some Chemical Characteristics of Anorthositic Suites and their Significance
Authors: Emslie R. F.
Published: April 2011

Spirited discussion continues about the nature of the relationship of rocks of anorthositic composition to intermediate and silicic rocks comprising so-called mangerites, charnockites, adamellites, etc. Because of close spatial association, all of these rocks may be considered to constitute an 'anorthosite suite' without prejudgement as to genetic implications.About 700 rock analyses, largely from the literature but supplemented by previously unpublished analyses from the Michikamau and Morin intrusions have been used to examine some of the chemical characteristics of the anorthosite suites. The suites are commonly high in iron relative to magnesium and alkalies, high in alumina, and have high K2O/SiO2 ratios over a wide range of SiO2 concentrations. The chemical data together with the physical characteristics of the anorthosite suites are interpreted to mean that the magmas are orogenically generated but emplaced on the flanks of orogenic belts in 'anorogenic' environments. Rapakivi granitic suites are chemically similar to the silicic members of the anorthosite suites.
Geomorphology and Geochemistry of a Gypsum Karst near Canal Flats, British Colombia
Authors: Wigley T. M. L. , Drake J. J. , Quinlan J. F. , Ford D. C.
Published: April 2011

A thick series of gypsum beds occurs in the Burnais and Harrogate Formations (Middle Devonian) and crops out in a belt 60 miles (100 km) long in the Kootenay Ranges, British Columbia. Landforms of an associated till-mantied gypsum karst were studied in the valleys of the Lussier River and Coyote Creek, southeast of Canal Flats. Karst features in the area include collapse sinkholes (some of which are ponded), springs and related ponors, caves, tufa deposits, geological organs, and solution breccias. Collapse sinkholes, the most common features, are discussed in detail, and it is shown that their origin can be much more complex than is generally recognized.Thirty-nine water samples from different hydrological situations in the two valleys were analyzed for solute concentration. Stepwise linear discriminant function analysis of the data revealed five distinct classes of water with calcium concentration, temperature, and the degree of saturation with respect to gypsum as the principal distinguishing variables. The results suggest that modern groundwater flow in the area is mainly through carbonate rather than the sulfate strata. Particular springs of high sulfate content indicate the proximity of the base of the gypsum. Hydrological and geochemical evidence suggests that sinkholes develop preferentially near the upper and lower contacts of the gypsum subcrop. The use of these indicators for mapping drift-mantled gypsum deposits is discussed.
Cratonic Reactivation in the Precambrian Basement of Western Canada. III. Crustal Evolution
Authors: Burwash R. A. , Krupička J. , Culbert R. R.
Published: April 2011

Relative to the Superior and Slave provinces, the Churchill province is enriched in K and Rb. The inferred mechanism of alkali enrichment involves diapiric uprise of mantle material from the base of the low velocity zone, in response to upward movement of water from the deep mantle. Intergranular fluid in the peridotite is enriched in K and Rb. At the base of the crust this fluid separates to enter deep-seated crustal shear zones. At upper crustal levels, reaction with permeable cataclasites causes K-metasomatism, involving especially the change of plagioclase into K-feldspar.Eclogite bodies within the peridotite, on moving upward to the base of the crust yield andesitic magma which separates to form sialic underplating. The existence of a discrete lower crust beneath southern Alberta, western Ontario, and northern Manitoba is shown by deep crustal reflection and refraction seismic studies.Generation of juvenile sial during the Hudsonian orogeny is indicated by initial ratios of whole-rock Rb–Sr isochrons for igneous rocks. During metasomatism, potassium and rubidium were added in the ratio of about 350:1. This ratio makes it unlikely that these alkalis were derived by anatexis of Kenoran crystalline basement.
Development of the Canyons of the South Nahanni River, N.W.T.
Authors: Ford D. C.
Published: April 2011

In its middle section, the South Nahanni River flows through four deep, meandering canyons incised through ranges of the southern Mackenzie Mountains. The downstream canyon, First Canyon, contains fossil solution caves of shallow phreatic type developed in limestone. The stratigraphy of the most extensive caves indicates that there was an interglacial climate between 300 000–200 000 years B.P., (from U Decay Series dating of stalagmites), which was preceded by a 'First Canyon Glaciation'. There has been no subsequent glaciation of the canyon and its environs. The position of the caves above the River, plus morphological evidence from cutoff meanders and a tributary canyon, indicates that since the First Canyon Glaciation the river has been entrenching into a rising anticlinal arch and that the maximum postglacial uplift of the arch has been not less than 1600 ft (486 m). The other three canyons of the South Nahanni River are also of antecedent type and are probably of similar age with a similar history.
Problems of Dating Mica by the Fission-Track Method
Authors: Lakatos Stephen , Miller Donald S.
Published: April 2011

Discordant 'fission-track ages' on mica may be caused by (a) non-uniform uranium distribution, (b) addition or loss of uranium during the existence of the mineral, (c) thermal annealing of tracks, (d) inefficient etching of fossil tracks as compared to induced tracks in the mica, and (e) the effect of water pressure on track stability. The result of the combined effect of these factors causing discordant 'fission-track ages' on mica is at present unpredictable. Therefore, in the case of mica, interpretation of such ages is suspect.
The Formation of Iron and Manganese-Rich Layers in the Holocene Sediments of Thunder Bay, Lake Superior
Authors: Mothersill John S. , Shegelski Roy J.
Published: April 2011

Thin iron and manganese-rich layers occur within or just below the initial stage of the Holocene sediments of Thunder Bay. Although more than one process may have been involved, most of the iron and manganese would appear to have been solubilized by connate waters under the reducing conditions of the early burial stage, subsequently migrated upward with the connate waters along vertical fractures during compaction, and then were eventually deposited as oxides along favorable Eh horizons under the oxidizing conditions of the initial stage of the syndiagenetic sequence.
A Model for Chemical Exchange in the Basalt–Seawater System of Oceanic Layer II
Authors: Hart Roger A.
Published: April 2011

In this paper evidence is presented in support of the hypothesis that the upper 2-3 km of oceanic layer II is a zone of chemical reaction between seawater and the oceanic crust as it moves away from the mid-ocean ridges.A model is constructed assuming that the principal alteration products resulting from the action of sea-water on primary basalts are:1. K-rich smectite formed during weathering of basalt,2. chlorite formed during retrograde metamorphism, and3. albite–actinolite formed during primary greenschist metamorphisms at the ridge crest.These three processes in combination could extract most of the stream input of K+, Mg2+, and Na+ and add SiO2, Ca2+, Fe2+, and Mn2+ to the ocean systems in amounts comparable to stream input.The steady state reaction of basalt with interstitial seawater to produce alteration minerals could exercise a strong influence in the chemistry of seawater and release energy in amounts sufficient to form a portion of normal heat flow measured on the ocean floor.
The Tremolite Isograd near Marble Lake, Ontario
Authors: Hutcheon Ian , Moore J. M.
Published: April 2011

Marble, metavolcanic rocks, and pelite are found in a northeasterly trending belt near Marble Lake, in the Grenville Province, Ontario. The rocks have been metamorphosed to the lower amphibolite facies in the southwest, the grade increasing to the mid-amphibolite facies towards the northeast. Northwest-trending isograds in the metavolcanic rocks are at a high angle to the northeast-trending tremolite isograd in the marbles. Mineral assemblages indicate total pressures between 4 and 5 kbar and temperatures ranging from approximately 350 °C to over 600 °C. Temperatures estimated by calcite–dolomite solvus geothermometry and applied to experimental work in the system CaO–MgO–SiO2–CO2–H2O indicate: (i) P(total) = P(CO2) + P(H2O) was greater than 3 kbars; (ii) temperatures on the tremolite isograd were from approximately 450 to 550 °C and indicate that the tremolite isograd is not isothermal; (iii) the composition of the vapor phase present during metamorphism was approximately X(CO2) = 0.7 – 0.8; (iv) temperatures in the belt were from less than 400 °C in the southwest to more than 600 °C in the northeast.
Biochemical Alteration and Heave of Black Shale; Detailed Observations and Interpretations
Authors: Quigley Robert M. , Zajic James E. , McKyes Edward , Yong Raymond N.
Published: April 2011

Detailed observations of the alteration products of sulfide oxidation in black shale at Ottawa, Canada, are presented using photographs taken at magnifications from times 1 to times 7000. X-ray diffraction analyses of the unaltered rock constituents and the alteration products, supplemented by X-ray fluorescence analyses are also presented.Growth of gypsum crystals imbedded in the shale appears to be responsible for the heaving reported for two buildings in Ottawa. Jarosite and natrojarosite alteration products, probably produced by bacterial action, fill open cavities and cracks in the rock. Jarosite commonly coats gypsum crystals imbedded in the shale and although probably critical to the overall alteration process may be of secondary importance in generation of heave pressures.Marcasite mineralization (probably hydrothermal) in a fault zone, plus the abundance of oxygen in the fractured rock, may play vital roles in the alteration.