bluuebunny/crossref_metadata_2025 huggingface dataset:
The Quantitative Analysis of Orientation Data obtained by the Starkey Method of X-Ray Fabric Analysis
Authors: Starkey John
Published: April 2011

The use of an X — Y recording microdensitometer and computer permits quantitative and automatic analysis of the crystal orientation patterns determined by the Starkey method. Three computer programs are used. Program REDUCE is specifically to interpret the X-ray diffraction photographs. Correction factors for background and absorption can be applied and the equivalent reflected and transmitted diffracted intensities can be used to normalize the data. The orientation pattern of the selected lattice plane is computed, plotted on a Lambert Equal Area, lower hemisphere projection.The remaining two computer programs are applicable to any orientation pattern represented in spherical projection. The first, CONTOUR, contours the data on the projected hemisphere. The data may be rotated prior to contouring. Program PREDICT enables the orientation of any crystallographic direction to be predicted from one or more measured orientation patterns.The procedure is illustrated by the analysis of quartz orientation in a quartzite from Bergsdalen, Norway.
Distribution and Transport of Suspended Particulate Matter in the Gulf of St. Lawrence
Authors: Sundby Bjørn
Published: April 2011

The distribution of suspended matter was studied in the Gulf of St. Lawrence. A three-layer distribution was found. In the surface layer, which was less than 50 m deep, concentrations of suspended matter ranged from 0.10 mgl−1 to 2.9 mgl−1. A relationship to the surface circulation pattern existed with the highest concentrations occurring in the low salinity surface outflow from the estuary. In the intermediate layer, which extended down to about 50 m above bottom, the concentrations of suspended matter ranged from 0.05 mgl−1 to 0.1 mgl−1. The intermediate layer, characterized by these concentrations, was found in all the deep areas of the Gulf. Concentrations of 0.1 mgl−1 to 0.4 mgl−1 were found in the bottom layer, with highest values occurring near the estuary.Budget calculations indicate that 5 × 106 tons/yr of suspended matter enter the Gulf from the rivers, and that erosion of the coastline and reworking of sediments are significant processes which contribute about 10.5 × 106 tons/yr of suspended matter. The net seaward transport at Cabot Strait is estimated as 5.5 × 106 tons/yr.
Fine Structure of the Crust near Yellowknife
Authors: Clee T. E. , Barr K. G. , Berry M. J.
Published: April 2011

A detailed reflection–refraction experiment was conducted near Yellowknife, Northwest Territories, in 1969. Over 3000 seismograms were recorded along two profiles with a geophone separation of 250 m. The high quality, quantity and unexpectedly high frequency content of the data has revealed a crustal structure which correlates well with the local geology and Bouguer gravity. Extensive use has been made of a ray-tracing program which includes an estimate of the amplitudes based on first-order seismic theory.The model includes a belt of greenstones to the east of the Yellowknife Fault, surrounded by granitic rocks. The velocities are, respectively, 6.17 and 6.0 km/s at depths of 1 km and greater, but the granites are overlain by a transition zone with the velocity at the surface being 5.5 km/s. In the granites at a depth of 8–10 km lies a low velocity layer (Vp = 5.8 km/s). The bottom of the greenstones corresponds roughly to the bottom of the LVL and both are underlain by a zone in which Vp = 6.2–6.4 km/s.The highly complex nature of the Mohorovičić reflection coda suggests that the M transition is characterized by strong lateral variations of velocity over 20 km or less which give rise to sideways reflections and interference patterns at the surface, t2, x2 calculations using some of the M reflections suggest a crustal thickness of about 30 km and an average crustal velocity of 6.22 km/s. Both values are considered low for a stable shield region.
A Pleistocene Clastic Dike, Upper Chaudière Valley, Québec
Authors: Dionne Jean-Claude , Shilts W. W.
Published: April 2011

At St. Ludger, Upper Chaudière Valley, in southern Québec, glacio-lacustrine sands of the Gayhurst formation which are older than 20 000 years B.P., are cut by a vertical till dike, 40 cm in width and more than 200 cm in height. The infilling materials are similar to those of the overlying Lennoxville till. The trend of the dike is at right angles to the major direction of flow of the last glacier. It is believed that infilling from above occurred when the Laurentides ice sheet overrode and fractured the underlying sands during the Wisconsin stage.
Devonian Boring Algae or Fungi Associated with Micrite Tubules
Authors: Kobluk David R. , Risk Michael J.
Published: April 2011

The process of skeletal micritization by boring thallophytes (algae and fungi) is known from modern carbonate environments and probably occurred as far back as the Ordovician. Boring thallophytes, probably fungi, possibly algae, were the cause of at least some skeletal micritization in Devonian reef complexes in western Canada. In situ endolithic filaments, of 3 μm and 5 μm diameter, occur associated with a micrite rim and micrite tubules in the corallite of an Upper Devonian tetracoral from the Miette reef complex. The filaments are found in the micrite rim around the coral, in the micrite tubules, and in unmicritized parts of the corallite, often oriented normal to the corallite wall and with the same trend as the tubules. Infestation and micritization began well before the corallite was buried, probably while the coral was alive, and continued for some time after death.
Note on Closure Correlation
Authors: Zodrow Erwin
Published: April 2011

Given a matrix of product-moment correlation coefficients computed on 'closed data' (a system of percentage variables), the test of departure from zero correlation is clearly inappropriate because closure of data imposes non-zero correlation.Subroutine CHAYES estimates 'Null Correlations' and calculates a t-matrix which may be used to test the hypothesis that observed product-moment correlations are due to the closure property. The calculated t-matrix is at best an approximation. This is found in certain mathematical assumptions leading to this t-test, and the recognition that statistical assumptions in the theory of t-testing are not satisfied. Great care must be exercized in accepting or rejecting correlations by this test. Therefore, results of the t-test are no substitute for sound geological reasoning, caveat emptor.
Magnetic Fabric in Massive Sulfide Deposits
Authors: Schwarz E. J.
Published: April 2011

The magnetic anisotropy of oriented sulfide samples from four massive sulfide ore (Ni–Cu) deposits associated with the Sudbury Irruptive and two sulfide deposits near Timmins, Ontario, is commonly well above 10%. This indicates that the anisotropy is mainly due to preferred orientation or to thin layering of random crystals of the strongly anisotropic magnetic pyrrhotite type Fe7S8 which occurs in all deposits sampled. The directions of the principal susceptibilities show patterns for most of the deposits indicating a consistent magnetic fabric within these deposits. The directions of the principal susceptibilities show varying degree of scatter, suggesting local modifications of the general patterns. In general the standard errors on the principal susceptibilities are only a few (< 5) degrees indicating that the magnetic fabric is of single origin and did not result from superimposed anisotropies. It is emphasized that in most cases, the magnetic fabric differs from deposit to deposit in the Sudbury area, suggesting that the fabric depends strongly on the geological environment of the deposits.
Manganese Spherulites at an Intra-Cretaceous Disconformity, Banks Island, Northwest Territories
Authors: Miall Andrew D.
Published: April 2011

Concretions ranging from 10 to 700 μ in diameter form a marker zone between the Christopher Formation (Albian) and the Kanguk Formation (Cenomanian to Maastrichtian) in three wells in western Banks Island. The concretions contain in excess of 30% rhodochrosite (MnCO3), plus minor quantities of dolomite, and iron and manganese oxides. Quartz sand and silt, clay, and sparry dolomite comprise the matrix between the concretions. The concretion zone ranges up to 40 ft (12 m) in thickness and is tentatively assigned to the Kanguk Formation.Manganese was probably derived by decomposition of contemporaneous volcanic rocks, possibly located offshore west of Banks Island. The metal was concentrated by ionic or molecular diffusion processes acting immediately below the sediment–water interface.Subsequent diagenetic recrystallization allowed for further manganese concentration and the development of a strong radial-fibrous crystal texture as the surrounding sediments were passively replaced. Concentric laminations were caused by further partial expulsion of impurities, probably including organics and iron and manganese oxides.
A Paleozoic Zircon Age of the Westcoast Crystalline Complex of Vancouver Island, British Columbia
Authors: Muller J. E. , Wanless R. K. , Loveridge W. D.
Published: April 2011

Zircons from the Westcoast Crystalline Complex near Tofino, Vancouver Island, have yielded the following ages: 206Pb/238U = 265 ± 7 m.y.; 207Pb/235U = 263 ± 7 m.y.; and 206Pb/207Pb = 244 ± 20 m.y. A K–Ar date of an amphibolized dike from the same outcrop yielded 192 ± 9 m.y. This is the first supporting isotopic evidence that the 'basement' complex is derived from late Paleozoic Sicker volcanic rocks and was ultimately migmatized during the major Jurassic plutonic event of Vancouver Island.
Perennially Frozen Peatlands in the Western Arctic and Subarctic of Canada
Authors: Zoltai S. C. , Tarnocai C.
Published: April 2011

Perennially frozen peatlands were divided into five morphological types: peat plateaus, polygonal peat plateaus, palsas, fen ridges and lowland polygons. One hundred and eight different peatlands were cored, measured and sampled. The internal structure of all but the lowland polygons suggests that the peat was deposited in wet fens unaffected by permafrost, and that permafrost developed only after a thin layer of Sphagnum covered them. The lowland polygons evolved in a permafrost environment. The study area was divided into four regions oh the basis of predominance of different peatlands forms.
Geochronology of Archean and Proterozoic Rocks in the Southern District of Keewatin
Authors: Wanless R. K. , Eade K. E.
Published: April 2011

Rb–Sr and U–Pb dating techniques have been utilized to identify and date Archean supracrustal rocks within the Churchill structural province in regions where K–Ar age determinations have recorded only the effects of younger Hudsonian orogeny. The age of emplacement of Archean granodiorite has been established at 2550 m.y., a determination that also provides a minimum age for volcanic rocks intruded by the granodiorite.The overlying Proterozoic Hurwitz Group volcanic rocks have been dated for the first time at 1808 ± 35 m.y. (Upper Aphebian). A post-Hurwitz Group quartz monzonite pluton intruded the granodiorite gneiss at 1772 ± 22 m.y. and the age of the post-tectonic Nueltin Lake Granite has been established at 1700 ± 16 m.y. (Paleohelikian).It is concluded that the Hurwitz Group cannot be correlated with the Huronian succession in Ontario as the Hurwitz Group rocks are 300 to 400 m.y. younger than the Huronian strata.
Measurement of Variations in the Total Geomagnetic Field at Sea off Nova Scotia
Authors: Srivastava S. P. , Folinsbee R. A.
Published: April 2011

Measurements of temporal variations in the total geomagnetic field were made at sea on the Abyssal Plain off Nova Scotia, Canada, during 1972 and 1973 from specially designed magnetometers housed in moored surface buoys. Comparison between the simultaneous recordings from sea and land stations shows enhancement in the land recordings from 10 min to 2 h periods with a maximum value around 30 min period. The trend of this enhancement is similar to that observed between Sable Island and Dartmouth and supports the previous interpretation of the presence of a high conductivity structure under the continental shelf. Comparison between the recordings made at sea and on land during the total solar eclipse of July 10, 1972 shows a phase lag of 11 min in the recordings at sea. This phase lag seems to agree with the eastward migration of the totality during this time.
Composition and Formation of Coronas in the Hadlington Gabbro, Ontario, Canada
Authors: Grieve Richard A. F. , Gittins John
Published: April 2011

Coronas of orthopyroxene, amphibole and spinel, and occasional garnet occur between olivine and plagioclase in olivine gabbros and troctolites of the Hadlington gabbroic complex. Microprobe analyses show that changes in olivine composition are mirrored in the composition of the corona minerals. Textural evidence indicates that corona formation was sub-solidus and Mg–Fe partitioning between ortho- and clinopyroxene suggests temperatures below 850 °C. Calculations of earlier models for corona formation based on equal volume replacement, or the simple addition of silica or alumina, fail to yield a satisfactory chemical balance. Olivine and plagioclase, with the addition of water, can supply the material needed for corona formation only if a migrating reaction boundary and change in olivine composition are considered.
The Dover Fault: Western Boundary of the Avalon Zone in Northeastern Newfoundland
Authors: Blackwood R. F. , Kennedy M. J.
Published: April 2011

Basement rocks of the Hare Bay Gneiss Complex and associated granitic intrusive rocks on the western side of Bonavista Bay, northeastern Newfoundland, are separated from clastic sedimentary and volcanic rocks of the Avalon Zone (Love Cove and Musgravetown Groups) by a 300–500 m wide mylonite zone called the Dover Fault. The Dover Fault juxtaposes rocks of contrasting lithology and metamorphic, intrusive, and structural histories and represents the boundary between the Gander Zone and the Avalon Zone of the Newfoundland Appalachian System. Structural relationships across the fault zone indicate that early movement on the Dover Fault was contemporaneous with deformation of the Love Cove Group. Relationships elsewhere in the Avalon Zone indicate that the Love Cove Group was deformed in Hadrynian time and hence the Dover Fault was probably initiated as an Hadrynian structural feature, probably related to Hadrynian orogeny on the eastern side of the Appalachian system.
The Mid-Atlantic Ridge Near 45°N. XXIII. Analysis of Bathymetric and Magnetic Data
Authors: Bhattacharyya P. J. , Hyndman R. D. , Keen M. J.
Published: April 2011

Bathymetric and magnetic data obtained from the Mid-Atlantic Ridge near 45°N have been analyzed numerically to determine trends, offsets and local structure. The estimates of regional trends in the data reveal that the average structural trend in this area is 17°E of north, made up of nearly north–south segments periodically offset by small right lateral displacements. The east–west offsets, not always visually manifest in contour maps of the data have been located by a cross-correlation scheme. Frequent small offsets may be the way a ridge crest accommodates to a spreading direction not perpendicular to the general trend of the crest. There is evidence for an old, now dead spreading center to the west of the median valley. This old center with an orientation of about 15°W, terminating in a right lateral transform fault has been abandoned in favor of frequent small offsets which provide smaller resistance to spreading.
Age and Geochemical Studies of the Snyder Breccia, Coastal Labrador
Authors: Barton Jr. Jackson M. , Barton Erika S.
Published: April 2011

The Snyder breccia is composed of angular to subrounded xenoliths of migmatites and amphibolites in a very fine grained matrix. It is apparently intrusive into the metasediments of the Snyder Group exposed at Snyder Bay, Labrador. The Snyder Group unconformably overlies a migmatitic and amphibolitic basement complex and is intruded by the Kiglapait layered intrusion. K–Ar ages indicate that the basement complex is Archean in age (> 2600 m.y. old) and that the Kiglapait layered intrusion was emplaced prior to 1280 m.y. ago. Major and trace element analyses of the matrix of the Snyder breccia indicate that while it was originally of tonalitic composition, later it locally underwent alteration characterized by loss of sodium and strontium and gain of potassium, rubidium and barium. Rb–Sr isotopic analyses show that this alteration occurred about 1842 m.y. ago, most probably contemporaneously with emplacement of the breccia. The Snyder Group thus was deposited sometime between 2600 and 1842 m.y. ago and may be correlative with other Aphebian successions preserved on the North Atlantic Archean craton.
The Lions Gate Member: A New Late Cretaceous Sedimentary Subdivision in the Vancouver Area of British Columbia
Authors: Rouse G. E. , Mathews W. H. , Blunden R. H.
Published: April 2011

Sediments bordering Burrard Inlet in Greater Vancouver are described as the Lions Gate Member of the Burrard Formation. This new member, comprising the lowest part of the previously defined Burrard Formation, rests nonconformably upon deeply weathered granitic rocks of the Coast Plutonic belt, and dips southwards into the Whatcom Basin. Four sedimentary units are recognizable, comprising a basal unit of conglomerate with minor sandstone lenticles; a sandstone–siltstone unit; a shale unit; and an upper coarse arkose. The upper contact with overlying sandstone and shales of Tertiary age occurs on the south shore of Burrard Inlet. Palynomorphs from both surface and borehole samples are of Late Cretaceous (Campanian) age, suggesting correlation of the Lions Gate Member with the Extension-Protection Formation of eastern Vancouver Island.
Evolution of Triple Junctions
Authors: York Derek
Published: April 2011

The condition for stability at a triple junction of three normally spreading ridges should read: all ridge orientations may be stable if and only if the three ridge elements occupy an angular spread of more than 180°. This consideration leads to the conclusion that, in one mode of formation of an RRR triple junction, at least one active ridge segment should be extinguished. A fossil rise in the east-central Pacific is examined as a possible illustration of the argument.
Middle Miocene Mammals from the Cypress Hills, Canada
Authors: Storer John E.
Published: April 2011

Parahippus sp., Hypohippus equinus, and Camelidae, gen. et sp. indet. have been collected from the Cypress Hills Formation in Saskatchewan, near the top of the section. The combination of taxa indicates a Hemingfordian (Middle Miocene) age for some deposits. I suggest a limited amount of Middle Miocene deposition before the uplift of the Cypress Hills Plateau.
Seismic Ground Motion and Residual Deformation near a Vertical Fault
Authors: Hasegawa H. S.
Published: April 2011

Ground motion and residual ground deformation at strategic points in the epicentral region of an idealized, vertical shear fault that may correspond to an intermediate magnitude (6–6½) earthquake are displayed and analyzed. For analytical purposes, Haskell's expressions for the elastic displacements near a propagating fault are separated into two parts, the near-field and the far-field terms. The distance from the fault at which the far-field terms are sufficient to describe the total field varies, depending upon the orientation of particle motion relative to that of the dislocation (slip) vector. For the component of particle motion parallel to the dislocation vector, this distance is comparatively greater than that for the perpendicular component. The Earth Physics Branch strain gauge, which has a threshold sensitivity of about 5 × 10−10, has the capability of detecting residual strain at least as far as 100 km from the hypothetical fault. The Earth Physics Branch tiltmeter, which can detect a step change in tilt in the range 5 × 10−9 to 5 × 10−10 radians, can detect residual tilt at least as far as 50 km from the causative fault.The high-frequency slope of the theoretical Fourier amplitude spectrum of ground acceleration (FS), is not appreciably steepened by the addition of the near-field to the far-field terms. The implication of this observation is that the steep slope observed at high frequencies on FS curves of predominantly California earthquakes cannot be attributed, even in part, to the source mechanism assumed but must be attributed entirely to travel path effects such as attenuation and scattering.
Further Studies of Reflections from the Deep Crust in Southern Alberta
Authors: Cumming G. L. , Chandra N. N.
Published: April 2011

The correlation between Bouguer gravity anomaly and depth to the 'Riel' reflecting horizon established in southern Alberta in the region around 113 °longitude and 51 °latitude is not substantiated on a smaller gravity anomaly further to the south. Only small variations in depth to the 'Riel' reflecting horizon occur and these do not correlate well with the gravity data. The reflecting horizons are continuous over distances of only a few kilometres. Model calculations of the reflecting zones based on an analysis of the variations in power spectra of the reflections indicate substantial changes in the layered reflecting zones over distances of the order of a few hundred metres. Some attempts at deconvolving the seismic data confirm that the prominent reflections are caused by rapid variations in reflection coefficients indicating finely layered zones a few hundred metres thick.
Late Quaternary Sediments and Geomorphic History of the Southern Rocky Mountain Trench, British Columbia
Authors: Clague John J.
Published: April 2011

The southern Rocky Mountain Trench was a major outlet valley of the Cordilleran Ice Sheet. Quaternary sediments underlying the floor of the trench in southeastern British Columbia consist mainly of glacial, glaciofluvial, and glaciolacustrine materials deposited during the Fraser (Pinedale) Glaciation, and fluvial and lacustrine sediments deposited during the preceding interglaciation.Deposits of three stades and two intervening nonglacial intervals are recognized. Interglacial sediments which contain wood dated at 26 800 ± 1000 y B.P. underlie drift of the early stade. During the interval between the early and middle stades, the Rocky Mountain Trench in southeastern British Columbia probably was completely deglaciated, and sediments were deposited in one or more lakes on the floor of the trench. In contrast, glacier recession between the middle and late stades was of short duration and extent; glaciolacustrine sediments were deposited only along the margins of the Rocky Mountain Trench, and apparently residual ice remained in the center of the valley. Final recession of the trunk glacier occurred prior to 10 000 y B.P. with no major halts and without significant stagnation of the terminus.
Ordovician Formations and Faunas, Southern Mackenzie Mountains
Authors: Ludvigsen Rolf
Published: April 2011

Ordovician strata of the South Nahanni River area occur as a western fine clastic facies with graptolitic faunas (Road River Formation) and an eastern carbonate facies with shelly faunas (Broken Skull, Sunblood, Esbataottine, and Whittaker Formations). The lithofacies are controlled by major tectonic features. In the early Ordovician the Selwyn Basin received fine clastic sedimentation (Road River) while carbonate sedimentation (Broken Skull, Sunblood, Esbataottine) was confined to the Root Basin and the fringes of the emergent Redstone Arch. Later in the Ordovician a pronounced transgression caused a marked eastwardly shift of facies belts and resulted in the flooding of the Arch and deposition of a widespread carbonate sheet (Whittaker) in the northeastern part of the study area.The carbonate facies of the Root Basin and south of the Redstone Arch contains a complete record of shelly faunas of Canadian to, probably, Maysvillian age. The Broken Skull Formation consists of craggy weathering, variably sandy carbonates and contains, in its highest parts, the Hesperonomia fauna (Canadian). The Sunblood Formation consists of generally resistant, red-orange-buff weathering limestones and minor dolostones and contains two faunas; the Orthidiella-'Goniotelina' fauna (Whiterockian) and the Bathyurus sp. 1 fauna (?Chazyan). The Esbataottine Formation (proposed) comprises moderately recessive, grey-buff weathering limestones and contains two faunas; the Mimella fauna (Chazyan) and the Doleroides fauna (Blackriveran). The lower Whittaker Formation (Trentonian to ?Maysvillian) comprises three lithosomes containing discrete faunas which appear to represent coeval communities: The Strophomena-Ceraurus fauna in thinly bedded, argillaceous limestones; the Bighornia-Thaerodonta fauna in well bedded, nonargillaceous limestones; and the Hesperorthis-Oepikina fauna in well bedded dolostones. A unique fauna of deep water aspect, the Cryptolithus-Anataphrus fauna, occurs in shales and black limestones of the Road River Formation and is, in part, equivalent to the faunas of the lower Whittaker Formation. The Sunblood, Esbataottine, and Whittaker Formations contain abundant and well preserved silicified trilobites; many of which are reported for the first time from western and northern Canada.
Crustal Loads and Vertical Movements near Lake St. John, Quebec
Authors: Dunbar W. Scott , Garland G. D.
Published: April 2011

Analysis of the free air gravity field between Quebec City and Lake St. John indicates that there is an uncompensated load, apparently resulting from dense topography, directly over the region of observed vertical movement of the crust. A finite element calculation for a viscoelastic model, in which Logan's Line is included as a zone of weakness, yields a profile of surface velocities which approximates those obtained by geodetic relevelling. It is proposed that the vertical movement represents the decay of an enhanced proglacial forebulge which was formed in a region partially decoupled from its surroundings by major faults.
Palynology and Paleoecology of Postglacial Sediments from the Lower Fraser River Canyon of British Columbia
Authors: Mathewes R. W. , Rouse G. E.
Published: April 2011

The postglacial history of vegetation in the Yale area of the lower Fraser River Canyon is described from sediments of two lakes using percentage pollen analysis supplemented with macrofossil evidence and radiocarbon dating. Deposition of postglacial sediments, ranging from basal clays to gyttjas, began about 11 500 y B.P. Three distinct pollen assemblage zones are distinguished, reflecting in part the main climatic conditions for the intervals. The oldest zone, with high percentages of pine (Pinus) and alder (Alnus) pollen, suggests cool and moist conditions following withdrawal of glacial ice. This is followed by marked increases in Douglas-fir (Pseudotsuga), grasses and other nonarboreal pollen, suggesting in part, warmer and drier conditions. The third zone, ranging from about the Mt. Mazama ash at 6600 y B.P. to the present, is marked by high alder and Douglas-fir, and increasing cedar (Thuja-Chamaecyparis type), western hemlock (Tsuga heterophylla), fir (Abies) and birch; an assemblage indicating a return to wetter conditions. This sequence contrasts with previously described successions that recognized the classical Hypsithermal in adjacent areas. The sequence of inferred vegetational changes, although similar to those described for the Haney area to the west, suggests that the Yale area has been a biogeoclimatically transitional area for much of postglacial time.
Fabrics and Deformation of Archean Metasedimentary Rocks, Ross Lake – Gordon Lake Area, Slave Province, Northwest Territories
Authors: Fyson W. K.
Published: April 2011

Metagreywackes, which lie stratigraphically above metavolcanics fringing a granitic complex (part basement), exhibit late Archean multiphase fold structures. F1 folds are large linear depressions and anticlinal culminations trending partly concordant with margins of the granitic complex. Open to isoclinal F2 folds vary and curve in trend. Though usually near upright, some F2 folds are overturned away from the complex and others towards F1 depressions. F3 folds are small-scale structures not present in most outcrops, but throughout a large region they are accompanied by a steep S3 axial-plane schistosity striking NW to N.Original orientations of an S2 schistosity, axial planar to F2 folds, are preserved as inclusion trails in biotite porphyroblasts. Angular deflections from the trails show that regional horizontal flattening across the S3 schistosity formed the F3 folds and tightened curved trends of F2 folds. Estimates of strain from the fabrics indicate no increase near the complex.As for folds in other Archean terrains, F1 and F2 folds could have developed mainly as gravity structures during diapiric uprise of a granitic basement. In contrast, the F3 structures may reflect horizontal movements of early crustal plates.
The Geology and Geochemistry of Ophiolitic Rocks Exposed at Ming's Bight, Newfoundland
Authors: Norman Ryburn E. , Strong D. F.
Published: April 2011

The Baie Verte Group, as exposed on the peninsula between Baie Verte and Ming's Bight, consists of an ophiolite assemblage ranging from interlayered ultramafic and gabbroic rocks to sheeted diabase dikes overlain by pillow lavas and volcanic sediments. The sequence has been disrupted into five structural blocks separated by fault zones containing serpentinized peridotite and/or talc-carbonate; units within each block are separated by less significant faults. These structures and other deformation features in the Baie Verte Group are interpreted to be related to early Ordovician emplacement with some effects of later Acadian deformation.The Baie Verte Group is chemically similar, both in major and trace elements, to other ophiolite sequences such as in Oman and Papua. A low-Ti and low-K tholeiitic magma crystallized under conditions of low oxygen fugacity in the upper crust beneath a mid-ocean ridge, producing the observed peridotite–pyroxenite–gabbro–diabase–pillow lava sequence.
K–Ar and Fission Track Geochronometry of an Eocene Thermal Event in the Kettle River (West Half) Map Area, Southern British Columbia
Authors: Medford G. A.
Published: April 2011

The Okanagan and Similkameen plutonic complexes west of the Okanagan Valley of south-central British Columbia yield K–Ar dates that range from 185 to 133 m.y. East of the Okanagan Valley Shuswap gneisses into which the plutonics intrude, and which may be as old as pre-midCarboniferous in age yield K–Ar dates between 59.9 and 47.4 m.y. This abrupt change, which approximately coincides with the Okanagan Valley, is a consequence of an intense thermal event in the early Tertiary which has reset K–Ar dates in the gneisses at shallow depths. Comparison of K–Ar, sphene and apatite fission track dates demonstrates that the heating affected the plutons west of the Okanagan Valley and that cooling of the Shuswap gneisses occurred at a rate in excess of 25 °C. per million years. The scatter observed in the older K–Ar dates of the plutonic complexes could be caused by post-emplacement heating with variable partial argon loss rather than by separate magmatic events. Thus, only the oldesl K–Ar dates obtained from the plutons may be significant as minimum ages for emplacement.
Pleistocene Muskoxen (Symbos) from Alberta and British Columbia
Authors: Harington C. R.
Published: April 2011

Skull fragments of the extinct muskox Symbos cavifrons from late Pleistocene gravels at Fort Saskatchewan and Saanich Peninsula, Vancouver Island are the first records of that species for Alberta and southern British Columbia respectively. The Alberta specimen shows that Symbos herds once grazed along the eastern flanks of the Rocky Mountains.The discovery of a muskox fossil (and remains of other ice age land mammals) on southeastern Vancouver Island suggests that land connected the island with the mainland during the late Pleistocene. Causes for such a land connection or connections are considered.
A Spinifex Rock from Munro Township, Ontario
Authors: Fleet M. E. , MacRae N. D.
Published: April 2011

The textural and compositional characteristics of a spinifex rock (MS-1) from Munro township, Ontario have been investigated in some detail. When projected into Mg–CaO–Al2O3 and CaO–MgO–FeO space, MS-1 appears late in the fractionation trends for peridotites, associated spinifex rocks and high Mg basalts. The latter trend extrapolates almost linearly to olivine tholeiite compositions.There are two types of blade megacrysts in the rock, both apparently representing preexisting olivine: (1) an earlier phase of composite, skeletal platy crystals of clinochlore, about 10 × 10 × 0.5 mm in size, which have a preferred orientation in the rock and show pronounced parallel growth development in the plane of the blades. The clinochlore is crystallographically related to the host olivine with c* and [100] parallel to a and b axis of olivine, respectively; (2) sheafs of oriented skeletal plates about 0.1 mm in shortest dimension which are completely altered to chlorite, calcite, magnetite and amphibole. The appearance of the composite blade megacrysts varies markedly with thin section orientation and this seems to account for the various types of blade (or platey) crystals reported in the literature. The interblade areas are largely of acicular and spherulitic pyroxene and interstitial groundmass. The acicular pyroxene is augite. Its composition varies considerably, especially with the area analysed, the greatest variations being in Cr, Ti and Na. The augite is characterized by high Al contents—preferentially accommodated in tetrahedral sites—and this leads to a distinctive field in Ti, Al plots compared to those for lunar and other terrestrial pyroxene. The rock also contains a few relict rounded olivine phenocrysts, amygdules, accessory chromite octahedra with magnetite rims, pentlandite and pyrrhotite.The Mg–Fe ratios for the clinochlore, augite and interstitial groundmass do not vary greatly from that of the whole rock value in contrast to the situation in a quenched plateau basalt.
Electrical Conductivity Models of the Crust
Authors: Dvořák Z.
Published: April 2011

Compositional crustal models (continental, subcontinental, oceanic) are used as a basis for a construction of the electrical conductivity distribution within the crust. In addition, the procedure incorporates other parameters, such as pressure, porosity, pore fluid salinity, and resistivity. Calculation is made in three steps. First, 'dry' models based on mineral conduction alone are constructed. Second, electrolytic conduction through the pore fluids is estimated from the Archie's Law. Both results are then combined to produce the final, 'wet' models. These appear to agree with generalized conductivity profiles for the stable continental areas, as well as with the published values for the oceanic crust. Magnetotelluric response curves calculated for the final models give, for each crustal type, a band of possible responses which agree well with theoretical and in situ results.
INPUT AEM Results from Project Pioneer, Manitoba
Authors: Dyck A. V. , Becker A. , Collett L. S.
Published: April 2011

The results of an airborne EM survey obtained with an INPUT system flown in the vertical-axis-receiver configuration have been assessed by the Geological Survey of Canada as favorable in terms of their potential contribution to the geological mapping carried out in the Project Pioneer study. Manitoba, Canada. Time-domain scale model profiles over the various conductor arrangements presented here have proven indispensable in the interpretation process. An outstanding example of this is the striking modification to an overburden anomaly made possible by the fortuitous location and dip of a conducting dike model below the overburden. The investigation indicates that during the course of an exploration survey, IN PUT data may be used directly to aid in the mapping of structural features or, indirectly in areas of conductive overburden, if the overburden is structurally controlled.
Geology and Ages of Buried Precambrian Basement Rocks, Manitoulin Island, Ontario
Authors: Schmus W. R. Van , Card K. D. , Harrower K. L.
Published: April 2011

The geology of the buried Precambrian basement under Manitoulin Island in northern Lake Huron, Ontario, has been re-evaluated on the basis of aeromagnetic data, well cuttings, core samples, and rubidium–strontium and uranium–lead geochronologic data on some of the subsurface samples. We conclude that the northern half of the island is underlain in part by Huronian metasedimentary rocks, but that these are absent from the southern part of the island, which is underlain by granitic, gneissic, and metavolcanic rocks. Granitic and gneissic rocks are also present under the northern half of the island.Geochronologic data show that rocks underlying major positive aeromagnetic anomalies are quartz-monzonitic composite plutons which are about 1500 ± 20 m.y. old. Surrounding metasedimentary. gneissic, and granitic rocks are at least 1700 m.y. old. No evidence was found for extrapolation of the pre-Huroman Archean basement beneath Manitoulin Island; if it is present it has been affected by younger metamorphic overprinting.The south west ward extension of the boundary zone between the Grenville Province and rocks to the west can he traced along the east end of Manitoulin Island on the basis of aeromagnetic data.
Geophysical Studies of North African Cenozoic Volcanic Areas: II. Jebel Soda, Libya
Authors: Ade-Hall J. M. , Reynolds P. H. , Dagley P. , Mussett A. E. , Hubbard T. P.
Published: April 2011

This study is the second of a series in which a main concern will be to try to establish the Neogene absolute motion of the African Plate. A combined paleomagnetic and K–Ar whole rock age dating study has been made of the Jebel Soda basaltic volcanic area of central Libya. Sixty basaltic flows were sampled in an area centered on 28°45′N, 15°30′E. Precisely defined paleomagnetic directions were obtained for 57 of the flows. Considerable attention has been given to the problem of data selection to obtain a best measure of the pole representing the dipole field during the period of volcanic activity. The equatorial nature of the directions, with equivalent poles extending continuously to 30°N latitude, provide a problem in data selection. Similar characteristics are apparent in the results of Schult and Soffel (1973) for the same area. A provisional average pole for the combined data sets, located at 73°N, 195°E(K: 26, A95: 5.6°) is significantly different from the geographic pole. Reasons for the 17 °divergence of paleomagnetic and geographic poles are discussed briefly.
Microclimatic Influences on Ground Temperatures and Permafrost Distribution, Mackenzie Delta, Northwest Territories
Authors: Smith M. W.
Published: April 2011

Variations in ground thermal regime were studied over a small area in the east-central part of the Mackenzie Delta, Northwest Territories, about 50 km northwest of Inuvik. Vegetation shows a successional sequence related to river migration and there is a complex interaction between vegetation, topography, and microclimate.Measurements from five sites show that significant differences in thermal regime exist beneath various types of vegetation. There is a general decrease in mean annual ground temperatures with increasing vegetation. The mean annual air temperature in this area is −9 °to −10 °C, but microclimatic factors lead to mean surface temperatures of between 0 °C and −4.2 °C.In summer, variations in net radiation account for the differences in ground thermal regime at the three sites on the slip-off slope. At the other two sites a surface layer of moss and peat leads to small values in ground heat flux and is instrumental in maintaining lower temperatures there. Removal of 10 cm of organic material at one site led to an increase of 3 °C in the mean daily 10 cm temperature.In winter, on the slip-off slope, variations in snow accumulation lead to ground temperature variations greater than those due to vegetation per se. Spatial variation of about 20 °C in ground surface temperature was measured in March 1970; during July and August 1970 the maximum spatial variation observed was only 10 °C. Differences of up to 6 °C in 1 m temperatures were measured over a distance of only 12 m. Snow cover is a permafrost-controlling factor in this area; where accumulations are greatest a talik has formed due to the insulating effect of deep snow.
Paleomagnetism and K-Ar Dating of Some Franklin Lavas and Diabases, Victoria Island
Authors: Palmer H. C. , Hayatsu A.
Published: April 2011

Lavas of the Natkusiak Formation and related diabase sills, Victoria Island, have single polarity remanence directions, which yield a paleomagnetic pole at 163°E, 07°S, which is similar to that obtained from the Coronation Sills of the adjacent mainland. These western Arctic poles are slightly, but significantly different from those obtained from Franklin sills and dikes exposed in the central and eastern Arctic. K–Ar data indicate no resolvable difference in age between the western and eastern Arctic rocks. Although the apparent K–Ar ages from the Victoria Island lavas and sills are discordant, the highest apparent ages are in agreement with a K–Ar isochron age of 625 m.y. obtained from samples of the least altered lavas.
Anisotropy of Magnetic Susceptibility of the Martin Formation, Saskatchewan, and its Sedimentological Implications
Authors: Rahman Aziz-ur- , Gough D. I. , Evans M. E.
Published: April 2011

The magnetic fabric of the sedimentary rocks of the Precambrian Martin Formation has been investigated in an attempt to delineate paleocurrent directions. One hundred specimens were studied from twelve sampling sites. At most of the sites, a primary depositional fabric was found with a well-marked foliation lying close to the paleohorizontal. This was substantiated by a strongly positive fold-test. Six sites possessed tightly grouped maximum susceptibility axes; a further three sites showed more dispersion but still permitted useful estimation of mean directions of lineation. The directions of paleocurrent deduced are consistent with earlier geological interpretations and suggest that the Martin Formation was deposited in a basin of rugged, block-faulted terrain.
Geology and Geochronology of the Wollaston Lake Fold Belt in Northwestern Manitoba
Authors: Weber W. , Anderson R. K. , Clark G. S.
Published: April 2011

Recent studies in the northeastern extension of the Wollaston fold belt in Manitoba suggest that Aphebian metasedimentary rocks of the southern Churchill province comprise a geosynclinal facies that is conformably overlain by a platform facies. A possible period of emergence and embryonic Hudsonian tectonism separates this lower sequence from a blanket of continental deposits, which is probably of large regional extent and includes part of the Hurwitz Group in the District of Keewatin.Rubidium–strontium total-rock isochron ages have been obtained for five rock units in the Kasmere Lake area of Manitoba. The ages reveal that the metasedimentary rocks of the Wollaston fold belt are bounded to the east by an Archean complex comprising a differentiated hypersthene-bearing rock series having a minimum age of 2745 ± 124 Ma (87Rb = 1.39 × 10−11 yr−1) and a quartz monzonite unit having a minimum age of 2636 ± 163 Ma.Hudsonian igneous rocks are mostly syn- to post-kinematic. The age of 1855 ± 62 Ma for a quartz monzonite of batholithic dimension coincides with the ages of similar syntectonic Hudsonian intrusions in the Northwest Territories. The age of 1800 ± 60 Ma obtained from a pelitic gneiss unit is a minimum age for the Hudsonian metamorphism and dates the end of the Hudsonian orogeny in this part of the Churchill province. An age of 1941 ± 25 Ma for a granitic gneiss along the western margin of the Wollaston fold belt indicates early or pre-Hudsonian magmatic activity.
Paleomagnetism of the Circum-Ungava Proterozoic Fold Belt (I): Cape Smith Komatiitic Basalts
Authors: Fujiwara Y. , Schwarz E. J.
Published: April 2011

A total of 397 oriented cores were taken from pillowed, columnar, and massive basalt of Cape Smith Island in northeastern Hudson Bay and from the adjacent mainland coast of Quebec. The thick series of basalts form part of the Circum-Ungava Proterozoic Belt which is of Aphebian (early Proterozoic) age. The lower portion of the basalt series contains pyrrhotite (Fe7S8) and did not yield useful paleomagnetic results. The magnetization of the upper portion of the series is carried by small quantities [Formula: see text] of magnetite. The directions of magnetization of the samples do not change much during alternating field and thermal washing, and show very good grouping. The available internal evidence on the age of the stable remanence is inconclusive. The pole position (20°N, 162°E, semi-axes of the 95% oval of confidence: 4 °and 5°) after correcting for tilt is about 70° west of the preHudsonian part of the polar wandering curve established from North American data. The uncorrected pole position (16°N, 107°W), which would apply if the magnetization was acquired at the time of the Hudsonian orogeny, is in the general area of paleomagnetic poles for rocks of similar age from other localities of the Canadian Shield.
Longusorbis cuniculosus: A New Genus and Species of Upper Cretaceous Crab; with Comments on Spray Formation at Shelter Point, Vancouver Island, British Columbia
Authors: Richards Barry C.
Published: April 2011

Eighty-three fossil crabs, belonging to a new genus and species, and interpreted to be mainly exuviae, were collected from concretions within the Spray Formation at Shelter Point, Vancouver Island, British Columbia. They are assigned to the family Carcineretidae and named Longusorbis cuniculosus. The excellent preservation of the fossil crabs is a consequence of being buried in their own dwelling burrows in the intertidal zone, and subsequent formation of concretions around the specimens very early during diagenesis. Several species of mollusc occur with the crabs, and the faunal assemblage is assigned to the Pachydiscus suciaensis Zone of late Campanian to early Maestrichtian age. The small part of the Spray Formation exposed at Shelter Point contains six units of detrital sediment deposited in environments inferred to range from shallow neritic to supratidal.
Structural Succession, Nomenclature, and Interpretation of Transported Rocks in Western Newfoundland
Authors: Williams Harold
Published: April 2011

The Humber Arm and Hare Bay Allochthons of Western Newfoundland are made up of a variety of sedimentary rocks and volcanic and plutonic rocks that originated toward the east and record the evolution and destruction of the ancient continental margin of Eastern North America. Five contrasting rock assemblages that constitute different structural slices are defined and delineated in the Humber Arm Allochthon. Six contrasting rock assemblages constitute the Hare Bay Allochthon. In each allochthon, the lower structural slices consist of sedimentary rocks and the highest structural slice consists of the ophiolite suite. The stacking order and mode of assembly indicate that progressively higher slices travelled increasingly greater distances, so that their present vertical superposition represents a former west-to-east juxtaposition.Most of the transported rocks have direct lithic correlatives in central Newfoundland. These occur west of the Dunnage Mélange, so that if the Dunnage marks the vestige of a North American subduction zone, then all the transported sequences once lay between a continental margin and a nearby oceanic trench.