bluuebunny/crossref_metadata_2025 huggingface dataset:
Stratigraphy and structure of a Late Wisconsinan salt collapse in the Saskatoon Low, south of Saskatoon, Saskatchewan, Canada: an update
Authors: Christiansen E A , Sauer E Karl
Published: April 2011

The Saskatoon Low is a collapse structure that formed as a result of dissolution of salt from the Middle Devonian Prairie Evaporite Formation. In this study, the collapse has affected the Upper Cretaceous Lea Park, Judith River, and Bearpaw formations of the Montana Group; the Early and Middle Pleistocene Mennon, Dundurn, and Warman formations of the Sutherland Group; and the Late Pleistocene Floral, Battleford, and Haultain formations of the Saskatoon Group. Locally, the collapse is about 180 m, which is about equal to the thickness of the salt. The first phase of collapse took place after deposition of the Ardkenneth Member of the Bearpaw Formation and before glaciation or during a pre-Illinoian glaciation. The second phase of collapse occurred during the Battleford glaciation (Late Wisconsinan). Prior to deposition of the Battleford Formation, the Saskatoon Low was glacially eroded, removing the Sutherland Group and the Floral Formation. After the glacial erosion, up to 110 m of soft till of the Battleford Formation and up to 77 m of deltaic sand, silt, and clay of the Haultain Formation were deposited in the Saskatoon Low. Lastly, the South Saskatchewan River eroded up to about 40 m into the deltaic sediment and tills before up to about 15 m of Pike Lake Formation was deposited. The Haultain and Pike Lake formations are new stratigraphic units.
A new ankylosaurid (Dinosauria: Ankylosauria) from the Lower Cretaceous of China, with comments on ankylosaurian relationships
Authors: Vickaryous Matthew K , Russell Anthony P , Currie Philip J , Zhao Xi-Jin
Published: April 2011

Amongst the fossil material collected by the Sino-Soviet Expeditions (19591960) to the Alshan Desert, China, was a large, virtually complete ankylosaur skeleton. Gobisaurus domoculus gen. et sp. nov. closely resembles Shamosaurus scutatus, but is distinct in having an unfused basipterygoidpterygoid contact and elongate premaxillary processes of the vomers. Although it is difficult to make a definitive taxonomic assignment without considering postcranial material, a preliminary phylogenetic analysis places Gobisaurus as the sister taxon of Shamosaurus, clustered as one of several successive outgroups of the Ankylosaurinae.
Definition of an Archean – Proterozoic crustal suture by isotopic studies of basement intersections from offshore wells in the southern Labrador Sea
Authors: Kerr Andrew , Wardle Richard J.
Published: April 2011

Eight hydrocarbon exploration wells in the southern Labrador Sea penetrated Precambrian basement rocks, adjacent to the course of a Lithoprobe marine seismic reflection survey. The rock types are mostly Early Proterozoic (1870–1800 Ma) calc-alkaline plutonic rocks or their metamorphic derivatives, but one example is a Middle Proterozoic (1270 Ma) anorogenic intrusion. These samples of buried basement document a transition from juvenile Proterozoic crust in the southeast (shown by εNd from +0.8 to +2.2) to ancient Archean crust in the northwest (shown by εNd from −2.7 to −7.0). However, initial Sr isotope ratios do not show such a clear pattern. The transition in εNd is similar to results of onland studies in Labrador and formerly adjacent south Greenland, and delimits the hidden edge of the North Atlantic Archean craton within the Early Proterozoic Makkovikian–Ketilidian Orogen. These results from close to the seismic profile confirm that regional reflectivity contrasts on either side of the isotopic boundary record fundamental differences between local Archean and Proterozoic crust. Southeast-dipping reflectors that broadly correspond with the boundary zone probably represent a collisional suture zone, along which juvenile terranes were probably placed structurally above the Archean craton.
Regional mapping of Precambrian basement beneath Phanerozoic cover in southeastern Trans-Hudson Orogen, Manitoba and Saskatchewan
Authors: Leclair A. D. , Lucas S. B. , Broome H. J. , Viljoen D. W. , Weber W.
Published: April 2011

The northern edge of Phanerozoic platformal rocks of the Western Canada Sedimentary Basin overlies the Flin Flon Belt (Trans-Hudson Orogen) in Manitoba and Saskatchewan. A program of regional mapping of the Phanerozoic-covered basement has been undertaken, involving the integration of high-resolution aeromagnetic and gravity data with extensive drill core information. Several major domains are recognized in the buried basement, each with a distinct lithotectonic character and potential field anomaly pattern. Three lithotectonic domains in the buried basement (Clearwater, Athapapuskow, and Amisk Lake domains) are characterized by northerly-trending positive gravity and aeromagnetic anomalies and correlate with the 1.92–1.83 Ga volcanic and plutonic rocks of the exposed Flin Flon Belt (Amisk collage and Snow Lake assemblage). An upper amphibolite grade orthogneiss complex (Namew Gneiss Complex), containing calc-alkaline intrusive rocks ranging in age from 1.88 to 1.83 Ga and screens derived from the older volcano-sedimentary rocks, is interpreted as the middle crust of a 1.88–1.84 Ga arc exposed in the Flin Flon Belt. Discordant intrusive complexes, such as the 1.830 Ga Cormorant Batholith, are centred on magnetic–gravity lows and truncate the structural trend of adjacent lithotectonic domains. Correlation of Flin Flon Belt geology with that beneath the Phanerozoic cover shows that its constituent lithotectonic elements have north–south strikes of up to 150 km, and form a predominantly east-dipping crustal section, consistent with Lithoprobe seismic reflection profiles.
Age and origin of the Boil Mountain ophiolite and Chain Lakes massif, Maine: implications for the Penobscottian orogeny
Authors: Kusky T. M. , Chow J. S. , Bowring S. A.
Published: April 2011

The Boil Mountain ophiolite complex of west-central Maine is widely interpreted to mark the Lower Ordovician Penobscottian suture between the Dunnage, Chain Lakes, and Gander terranes. The ophiolite consists of two distinct volcanic groups, including a lower island-arc tholeiite sequence and an upper mid-ocean-ridge basalt sequence. A new Middle Ordovician 477 ± 1 Ma U–Pb age on a tonalite sill that intrudes the lower volcanic–gabbroic sequence is younger than other ca. 500 Ma age constraints for the ophiolite and represents a maximum age for the ophiolite prior to final emplacement over gneissic rocks of the Chain Lakes massif. A comparison of ages and paleogeography of the Boil Mountain ophiolite with ophiolitic sequences in Quebec and Newfoundland indicates that the Taconian and Penobscottian orogenies and ophiolite obduction occurred simultaneously, although on different margins of the Iapetus Ocean. The Taconian ophiolite sequences were obducted onto the Appalachian margin of Laurentia during its collision with the Notre Dame – Bronson Hill belt in the Middle Ordovician, whereas the Boil Mountain ophiolite was obducted onto the Gander margin of Gondwana during its collision with the Exploits subzone – Penobscot arc of the Dunnage terrane in the Lower – Middle Ordovician. We suggest that the lower volcanic–gabbroic sequence of the Boil Mountain ophiolite represents the fore-arc ophiolitic basement to the Penobscot arc. Middle Ordovician rifting of the Penobscottian orogenic collage on the Gander margin formed a new volcanic sequence (Popelogan arc) in front of a growing back-arc basin, and erupted the upper tholeiitic sequence of the Boil Mountain ophiolite in a back-arc-basin setting. The tonalité sill formed during this event by partial melting of the lower volcanic–gabbroic sequence. Spreading in this back-arc basin (Tetagouche basin) brought a fragment of the Gander margin (Chain Lakes massif), along with an allochthonous ophiolitic cover (Boil Mountain complex) across Iapetus, where it collided with the Taconic modified margin of North America in the Late Ordovician and was then intruded by the Ashgillian Attean pluton.
Paleochemistry of Lakes Agassiz and Manitoba based on ostracodes
Authors: Curry B. Brandon
Published: April 2011

The ionic composition and salinity of Lake Manitoba and its late-glacial precursor, Lake Agassiz, changed significantly over the past 11 000 years. The paleochemical record reported here is based on modern analog environments of ostracodes identified in a new 14.5 m core from southern Lake Manitoba. The ionic composition of Lake Manitoba today is dominated by Na+, Cl−, and HC03−, with much less Ca2+, Mg2+, and K+. Evaporative concentration of modern Lake Manitoba water would lead to greater salinity and the near depletion of Ca2+due to continued precipitation of calcite. During periods of highest salinity in the Holocene, however, Lake Manitoba supported Limnocythere staplini. Today this species inhabits waters in which [Ca2+] > [HCO3−], including springs associated with groundwater in Paleozoic bedrock discharging into Lake Winnipegosis (and eventually, after much dilution, into Lake Manitoba). Further complicating the Holocene record are intervals containing Limnocythere friabilis that suggest periodic influxes of dilute water, probably from the Assiniboine River, which bypasses Lake Manitoba today. The variations in Holocene paleochemistry indicated by the ostracode record imply changes in the proportion of overland flow plus precipitation relative to groundwater inputs to Lake Manitoba, independent of changes in evaporation relative to precipitation.
Timing of high-pressure metamorphism in the Yukon – Tanana terrane, Canadian Cordillera: constraints from U – Pb zircon dating of eclogite from the Teslin tectonic zone
Authors: Creaser Robert A. , Heaman Larry M. , Erdmer Philippe
Published: April 2011

Zircon from eclogite near Last Peak in the Teslin tectonic zone yielded a U–Pb isotopic age of 269 + 2 Ma (2σ), the first precise age for such a rock in the Yukon –Tanana terrane of the Canadian Cordillera. Both the morphology and geochemistry of the eclogitic zircons indicate a metamorphic origin, and the U – Pb age therefore constrains the timing of peak high-pressure metamorphism in this rock. The U – Pb age demonstrates for the first time that an Early Permian high-pressure metamorphic event occurred in rocks now making up the Teslin tectonic zone, and possibly elsewhere in the Yukon – Tanana terrane. This U – Pb age provides a new geochronologic "pin" in the evolution of the Yukon – Tanana terrane prior to its Mesozoic accretion to the North American continental margin and, combined with recent 40Ar/39Ar muscovite data, indicates that high-pressure metamorphism at this time was a relatively short-lived event.
SEISMIC STUDIES ON THE EASTERN SEABOARD OF CANADA: THE ATLANTIC COAST OF NOVA SCOTIA
Authors: Barrett D. L. , Berry M. , Blanchard J. E. , Keen M. J. , McAllister R. E.
Published: April 2011

The results of seismic refraction profiles on the Atlantic coast of Nova Scotia and on the continental shelf off Nova Scotia are presented. Compressional and shear waves have been observed in the crust and mantle and suggest that the thickness of the crust is about 34 km. The compressional wave velocities recorded in the main crust and upper mantle are 6.10 and 8.11 km s−1 respectively. No compressional waves with values of velocity between these values can be identified, and this suggests that any "intermediate" layer is thin or absent. The corresponding shear wave velocities are 3.68 and 4.53 km s−1. Values of Poisson's ratio in the crust and mantle are 0.22 and 0.28. Alternative models of the crust which, on the evidence of travel times, might fit the observed results are discussed.
A FLAKE TOOL AND A WORKED ANTLER FRAGMENT FROM LATE LAKE AGASSIZ
Authors: Kenyon W. A. , Churcher C. S.
Published: April 2011

A crude stone chopper and a worked left antler fragment have been recovered from Lake Agassiz II beds near Morson, Rainy River District, Ontario. The stone chopper resembles other stone implements surface collected in Rainy River District. The antler fragment is identified as probably Alces alces, and has been dated by 14C at 5 898 B.C. ± 423 years. The antler fragment shows two opposed dorsal and ventral grooves and other signs of working by Homo, the toolmarks in the grooves and on the shaped surfaces suggesting the use of a beaver-tooth adze and a hand ax respectively. This is believed to be the oldest dated report of North American Alces coeval with Homo.
GLACIAL FEATURES OF THE QUETICO-NIPIGON AREA, ONTARIO
Authors: Zoltai S. C.
Published: April 2011

The surficial deposits, ice movements, and glacial lakes are described within an area of 25 000 square miles in northwestern Ontario. Field studies and subsequent interpretation of aerial photographs suggest the existence of two major and one minor ice mass during late Wisconsin glaciation. Movements by the various ice masses are shown and correlated. The extent of several glacial lakes and their drainage channels are described. A reconstruction of the sequence of events, based on morphological features, allows a tentative correlation of Glacial Lake Agassiz in the west with Glacial Lake Minong stages in the Superior basin. A radiocarbon date of 9 380 ± 150 years B.P. (GSC No. 287) was obtained from wood buried in a post-Minong beach.
THE DESIGN AND TESTING OF AN ALTERNATING-FIELD DEMAGNETIZING APPARATUS
Authors: Larochelle A. , Black R. F.
Published: April 2011

An apparatus used at the Geological Survey of Canada for magnetic cleaning purposes is described. With this apparatus viscous components of remanent magnetization were effectively removed from a group of uniformly magnetized specimens although an appreciable scattering in magnetization directions was observed after treatment at high peak field intensity. Tests were conducted to verify that the scattering was not inherent in the design of the apparatus.
DÉSAIMANTATION THERMIQUE ET ANALYSE STATISTIQUE DES DIRECTIONS DE SÉDIMENTS CARBONIFÈRES ET PERMIENS DE L'EST DU CANADA
Authors: Roy J. L.
Published: April 2011

Thermal demagnetization of red beds (109 specimens, 42 sites) from the Maritimes and Gaspé shows that the fossil magnetization consists of a large, thermally stable component and of small, unstable components that disappear at about 400 °C. Thermal cleaning of the whole collection was therefore carried out at 450 °C to demagnetize these soft components. This procedure changes the mean declination and inclination by 6° and 7° respectively and also changes the distribution of directions about the mean. A statistical analysis shows that the site mean directions (after demagnetization) obey a Fisher's (1953) distribution whereas the individual specimen directions do not. This result is of interest in two connections: first, it shows that, in this instance, the use of Fisher's (1953) statistics to analyse the results is not permissible when unit weight is given to the specimen, but that their use is legitimate when unit weight is given to the site; second, the result is consistent with the hypothesis that the earth's field, when sampled in this way (paleomagneticalty), can be represented by an axial geocentric dipole field perturbed by randomly directed magnetic components at the earth's surface. Comparison with other results available for this geological period shows a certain divergence among the paleomagnetic poles for North America. It is suggested that a partial demagnetization of these earlier collections might reduce the observed divergence.
THE PORT TALBOT INTERSTADE OF THE WISCONSIN GLACIATION
Authors: Dreimanis A. , Terasmae J. , McKenzie G. D.
Published: April 2011

The Port Talbot interstade is a cool, long, nonglacial interval separating the Early from the Late or Main Wisconsin in the Lake Erie region. Recent test borings at its type locality, lithologic and palynologic investigations of the cores, and new radiocarbon dates suggest that this interval was considerably longer than previously assumed. It began more than 48 000 years before present (B.P) and ended, if the Plum Point interval is included, 24 000 years B.P.The entire nonglacial interval comprises two relatively warm episodes, with boreal climate (Port Talbot I and II), separated by a brief glacial readvance that reached Lake Erie from the north; 100 varves were deposited during this readvance. Another similar readvance separates the Port Talbot I beds from the Plum Point (?) sands and silts. Pine (Pinus) and spruce (Picea) pollen predominate throughout the section, with relative abundance of oak (Quercus) in the Port Talbot I green clay. The pollen assemblages are dissimilar from those of the Sangamon interglacial or postglacial in southern Ontario.
MID-ATLANTIC RIDGE NEAR 45° NORTH: I. THE MEDIAN VALLEY
Authors: Loncarevic B. D. , Mason C. S. , Matthews D. H.
Published: April 2011

Detailed maps of bathymetry, free air gravity anomaly, and total field magnetic anomaly are presented for an area approximately 50 × 20 mi along the crest of the ridge. The median valley and the associated belt of large positive magnetic anomalies are continuous and display a striking lineation in direction 019°. The free air gravity anomaly shows a strong resemblance to topography. This correlation disappears when the Bouguer anomaly is calculated, indicating that the intrusive body immediately underlying the median valley is not significantly different in density from those bodies beneath the elongated sea mounts which overlook the valley. Small variations in the Bouguer anomaly indicate that there is an increase in density in a northwest direction across the survey area. Magnetic anomalies within the surveyed area can be simulated by a two-dimensional model in which steeply dipping contacts separate blocks of rock having different magnetizations. These blocks could be entirely within the volcanic layer extending to a depth of 5 km below sea level, but the central block, underlying the median valley, must be much more strongly magnetized than those adjacent to it. The mechanism by which the valley was formed remains obscure.
THERMAL TRANSFORMATIONS OF STILBITE
Authors: Aumento F.
Published: April 2011

Stilbite samples from two localities were examined. Preliminary D.T.A. and T.G.A. investigations to 1 400 °C were followed by high temperature diffractometry. Debye–Scherrer and Guinier techniques were used to study cooled samples, Diffractometer and single crystal data were processed with a computer to calculate cell parameters and thermal expansion.Stilbite changes to a metastable form of epistilbite at 145 °C. At 240 °C and 470 °C epistilbite shows two modifications followed by gradual destruction. Semi-amorphous silica formed by this process yields β-cristobalite and anorthite at 920 °C. Anorthite is replaced, at 1 340 °C, by an unidentified cubic phase. β-Cristobalite is found to be metastable down to room temperature; its room temperature cell parameter "a" is inversely proportional to the maximum temperature of annealment.
THE HOLOTYPE (PLASTOTYPE) OF ?TITANITES OCCIDENTALIS FREBOLD FROM THE KOOTENAY SANDSTONE (UPPER JURASSIC) OF SOUTHERN BRITISH COLUMBIA
Authors: Westermann G. E. G.
Published: April 2011

The supplementary description of the giant ?T. occidentalis is based on the "holo-plasto-type", including the hitherto unknown densely ribbed penultimate whorl. After discussion of affinities and geological age, Freebold's original suggestions are tentatively supported.
MEASUREMENT OF THE MICROSEISMIC SPECTRUM AT OTTAWA, ONTARIO
Authors: Russell R. D. , Kollar F.
Published: April 2011

A recording seismograph was assembled from commercially available components and by use of a 3/32 inches per second FM tape transport. The system was calibrated by three independent techniques, one of which included the Honeywell spectral analyzer which was used for data analysis. System linearity was checked by comparing the results of sine-wave and impulsive excitation.Microseism spectra were recorded at approximately 1:00 a.m. local time on July 18 and November 1, 1964. They represented on both occasions averages over a 1-hour period. The spectra were similar in shape but different in amplitude. In both spectra the peak ground amplitude per octave occurred at about 5.2 seconds period, and was 360 millimicrons per octave and 2.1 microns per octave for the two occasions, respectively.
PHOTOGRAMMETRIC MEASUREMENTS OF THE ICE WASTAGE AND MORPHOLOGICAL CHANGES NEAR THE CASEMENT GLACIER, ALASKA
Authors: Petrie G. , Price R. J.
Published: April 2011

Two sets of maps were compiled for the Casement Glacier and its outwash area from aerial photography taken m 1948 and 1963 and plotted on a Wild B-8 aviograph. The major problems resulted from lack of measured ground control; they were overcome by stereotemplet triangulation for planimetric control and by the use of the extensive bodies of water to provide both model levelling and a height datum. An analysis of the accuracy of the results is made. Comparison of the two sets of maps reveals extensive ice wastage, with a maxi mum retreat of the ice front of 1.5 km. Large masses of stagnant ice have been detached from the glacier and covered by fluvioglacial deposits. The development of landforms in these deposits resulting from the wastage of the buried ice is discussed.
FABRIC OF A MIDDLE ORDOVICIAN LIMESTONE AT COLBORNE, ONTARIO
Authors: Lee P. J. , Winder C. G.
Published: April 2011

The varieties of limestone in the Middle Ordovician Cobourg Formation at Colborne, Ontario occur as follows: sparse biomicrite, 49%; fossiliferous micrite, 26%; biosparite, 23%; micrite, 2%; and packed biomicrite, trace.Some individual beds display a sequence of sedimentary structures composed of graded bedding at the base, followed by a zone of lamination, and structureless micrite at the top. Most disarticulated brachiopod and ostracod shells are convex upward in biosparite and convex downward in biomicrite and fossiliferous micrite. The percentage of brachiopod shells decreases towards the top of the quarry and changes laterally. Mechanical orientation patterns of elongate fossils show two dominant trends, NE–SW and NW–SE. Factor analysis suggests that the association of brachiopod shells and pelmatozoan fragments was controlled by a common environmental influence, that the bryozoa and ostracod remains were transported together with reworked quartz grains, whereas the distribution of trilobite fragments was controlled by another condition.The carbonate sedimentation occurred in a marine environment of generally low turbulence. Stronger currents were introduced sporadically to form graded and non-graded biosparites.
TRACE ELEMENTS IN TILLS OF ALBERTA
Authors: Bayrock L. A. , Pawluk S.
Published: April 2011

Analysis of 475 Keewatin till samples from the Alberta Plains shows well-defined trends in the distribution of certain minor constituents and trace elements. Fe and Cu are most abundant in tills from the Clear Hills region of northwestern Alberta, in which area thin but widespread beds of iron-formation outcrop. Zn distribution in till also is related to bedrock composition and, together with Fe and Cu, is useful in delineating bedrock subcrop patterns. The distribution of CaO, although related to the carbonate content of the underlying bedrock on a regional scale, has been modified to some extent by glacial processes, as demonstrated in the Caribou Mountains area of northernmost Alberta.
MASTODONS, THEIR GEOLOGIC AGE AND EXTINCTION IN ONTARIO, CANADA
Authors: Dreimanis A.
Published: April 2011

Most Canadian occurrences of mastodons are from southern Ontario. About four-fifths of them have been found below Lake Warren shore, thus being younger than 12 400 years B.P.; the youngest radiocarbon date is 8 910 ± 150 years B.P. Though most mastodons entered Ontario after the retreat of the Wisconsin ice sheet, a few occurrences may belong to the Mid- and Early Wisconsin interstadials. Association of spruce pollen with mastodon bones and concentration of mastodons in the poorly drained lacustrine plains during the late-glacial and early postglacial time suggest that mastodons preferred spruce forests or woodlands. The extinction of mastodons might have been initiated by gradual shrinking of these spruce forests, and completed by their disappearance from southwestern Ontario, owing to increasing warmth and dryness of postglacial climate, and improvement of drainage along the lowered Great Lakes. Mastodons did not find their way to the northern boreal spruce forests, being separated from them by a wide belt of pine and hardwood forests, which meanwhile had developed over the better drained morainic areas of southern Ontario. Weakened by less suitable food, mastodons became more sensitive to diseases and an easier prey to the Paleoindians.
USE OF A CONVENTIONAL ECHO-SOUNDER AND TEXTURAL ANALYSES IN DELINEATING SEDIMENTARY FACIES: SCOTIAN SHELF
Authors: King Lewis H.
Published: April 2011

The topographical features of the Scotian Shelf within the study area consist of two elongated basins and three isolated banks. The configuration conforms in a general manner to that of other formerly glaciated shelves.A variety of sediments occurs in the area and has been mapped in terms of an echogram classification. The classification is based on the shape of the surface of the bottom, as well as the relative degree of compaction of the sediment. An echo-sounder with a short pulse length and relatively high frequency was found particularly suited for this purpose.The data from textural analyses on 141 samples correlate well with the echo-gram results. Together, these techniques constitute an effective approach to the problem of obtaining a detailed picture of the surficial bottom geology, and in addition, stratigraphic relations are sometimes revealed. The sedimentary units or facies are interpreted in terms of depositional environments.The study suggests that the area was covered with glacial drift during the Pleistocene epoch and that subsequently, during a low stand of sea level indicated by a submarine terrace at 110–115 m, the glacial debris was reworked around the topographic highs and much of the finer sediment was transported and deposited in the adjacent basins.
A TIME-TERM ANALYSIS OF THE FIRST ARRIVAL DATA FROM THE SEISMIC EXPERIMENT IN HUDSON BAY, 1965
Authors: Ruffman Alan , Keen M. J.
Published: April 2011

A time-term analysis is made of the first arrival data from the 41 shots of the1965 Hudson Bay seismic experiment. An investigation of the water-wave data is made to determine which of three possible series of navigation is most consistent. A single-layered crust with a compressional wave velocity of 6.33 km/s and an upper mantle compressional wave velocity of 8.27 km/s are proposed for Hudson Bay. The Mohorovičić discontinuity is found to have considerable topography with depths ranging from 42.7 km to less than 26 km. The Churchill–Superior boundary is proposed to be a three-dimensional crustal feature and is extended offshore from Cape Smith and extended westward to the north of the Ottawa Islands through approximately 59° 40′ N and 82° 00′ W. The Mohorovičić discontinuity rises to depths of about 26 km beneath Chesterfield Inlet and Baker Lake. The mantle is about 40 km deep at Churchill, Manitoba and rises to about30 km some 130 km west of Gilmour Island, then drops to almost 42 km farther east. The sudden drop is related to the Churchill–Superior boundary.
THE OPTICAL ABSORPTION SPECTRA OF SOME ANDRADITES AND THE IDENTIFICATION OF THE 6A1→4A14E(G) TRANSITION IN OCTAHEDRALLY BONDED Fe3+
Authors: Manning P. G.
Published: April 2011

The optical absorption spectra of andradites from three different localities are reported. The spectra show a very sharp d–d band at 22 700 cm−1 (440 mμ) that has been assigned to electronic transitions to the first field-independent state (4A14E(G)) in octahedrally bonded Fe3+. A strong broad d–d absorption at 19 000 cm−1 in the high-Ti andradite (melanite) has been assigned to octahedrally bonded Ti3+. The andradites also show broad bands at 12 500 cm−1, 16 500 cm−1, and 21 400 cm−1 that are part of the Fe3+ spectrum.The andradite spectra have been compared to the spectrum of an almandine-pyrope. The conclusion is reached that the Fe3+ octahedra in andradite and the pyralspite garnets are different. There is no justification, therefore, in giving an almandine-pyrope (that contains Fe3+) an andradite content on the basis of Fe3+ analyses. The Fe3+ atoms in pyralspites are better regarded as impurity ions.
A PRELIMINARY STUDY OF THE COMPOSITION OF PRECIPITATION IN S.E. ONTARIO
Authors: Rutherford G. K.
Published: April 2011

As a prelude to the study of chemical weathering of rocks and soils in S.E. Ontario, a study of the composition of precipitation waters at 12 sites within the area was initiated. Analyses of bulk precipitation of both rainfall and snowfall are presented and compared with similarly derived results in other areas.The silica and aluminum contents are regarded as being high, although in snow silica is absent and aluminum is quite high. Areal differences in silica content appear to be connected with local differences in lithology. Iron occurs in the same concentrations as aluminum and is probably derived from atmospheric dusts. The sodium content is high, especially when compared with inland sites in other areas. Potassium is generally somewhat lower than sodium. Although the calcium content may reflect local differences in lithology, the dissolved magnesium is surprisingly uniform. Lithological differences in the area are also reflected in the significantly higher nitrate-nitrogen concentrations in the limestone area. Snowfall is markedly high in sulfates, which is considered to be a function of climatic and industrial causes. The high chloride concentrations in such a 'non-marine' environment are not explained.
Deriving contour maps from geological data
Authors: Newton R.
Published: April 2011

A simple technique is presented for the derivation of contour maps from geological data. Non-significant discontinuities in the data are eliminated by the assumption of a spatial probability function, which ideally reflects the variation that would occur if extensive sampling were carried out over a small region. At the same time this 'smoothing' of the data produces a grid network of 'most probable' values over the map area, allowing the required isoplethes to be located.
Evidence for diagenetic remanent magnetization in the Maringouin Formation
Authors: Roy J. L. , Robertson W. A.
Published: April 2011

Samples were obtained at 13 sites in the Maringouin Formation (late Mississippian red sediments) in New Brunswick and subjected to routine thermal demagnetization. After thermal cleaning at 550 °C, the results fall into two groups of comparable stability, but with different mean directions, direction dispersions, and intensities. Group I directions have a small dispersion (mean 179°, + 21°; k = 46; pole 117° E 34° N) after correction for folding. The folding was early Pennsylvanian so that the magnetization was acquired before that time. Comparison with results from somewhat younger formations indicates that there was an apparent polar shift of about 14° between late Mississippian-early Pennsylvanian time and late Pennsylvanian-early Permian time. Group II directions, although thermally stable, have a large dispersion (mean k = 4) and the intensities are generally lower than those of Group I. The Group II results may be explained by supposing that the magnetization was acquired not at a single point in time, but by one or more processes operating over a considerable period as the rock became lithified. If the field reversed during this time, the resultant magnetization will be the vector sum of an early magnetization acquired at or soon after deposition and a later one, roughly anti-parallel, acquired during diagenesis. This hypothesis explains the present data. It may also provide an explanation of 'transitional' directions observed during reversals in deep ocean cores and other paleomagnetic observations yielding 'strung' distributions. It is possible that in sediments lithified during a period of single polarity, the integrating effect of the diagenetic magnetization may reduce the between-site dispersion so that estimates of secular variation will be systematically too small.
Contribution à la connaissance du précambrien récent en Europe Occidentale et développement géochronologique du Briovérien en Bretagne (France)
Authors: Leutwein F.
Published: April 2011

The study of Precambrian formations in central and western Europe has interested geologists for a long time. Most of these presumed Precambrian rocks are actually gneisses, whose last metamorphism occurred in the Hercynian orogeny, so that chronostratigraphic investigations (that is, investigations of the typical stratigraphic evolution) are not possible. However, there are several regions where Precambrian rocks have not been transformed by the later Hercynian orogeny; these are situated in Bohemia (Czechoslovakia), in Thuringia (Eastern Germany), in the Cantabrian Mountains (Spain), and in several regions of France, especially in Brittany. All of the rocks in these regions are petrographically rather monotonous and fossils are rare and of untypical species. Only the combination of classical geological methods with isotopic analyses (K-Ar and Rb-Sr) of suitable rocks has permitted the development of a chronological and stratigraphical scheme in Brittany.The oldest rocks, highly metamorphosed, belong to the Pentevrian, with ages of 900–1200 m.y. The Pentevrian is an orogenic unit and not a stratigraphic one. After a period of 150–200 m.y. for which no record of sedimentation and erosion remains, the upper Precambrian (Brioverian) stratigraphie system began. Older ages than the Pentevrian are presently known only in northern Europe.The stratigraphic subdivisions previously proposed for Normandy and Brittany can be confirmed by radioactive datings. The system began with arkoses and basaltic volcanic ashes (700 m.y.), followed by important submarine diabases (670 m.y.). Following them, the middle Brioverian began without any tectonic movement, with some thin horizons of black silica schists of about 630 m.y. and continued with very fine-clastic schists and shales several hundred meters thick. After a tectonic phase, the upper Brioverian period commenced, with important phyllitic (flysch) series, which show in the upper parts tillites and other glacial phenomena. This period was followed by important tectonic movements, folding, and granitic intrusions, including the great granitic pluton in western Normandy at 560 m.y. After an evidently short period of erosion the Georgian (Cambrian) period commenced, with a transgression conglomerate.These results are briefly compared with the evolution of the younger Precambrian in the other European regions. Except for northern Europe and the British Isles the same stratigraphic and tectonic scheme appears in each region.
Rb–Sr whole-rock age of the Sudbury lopolith and basin sediments
Authors: Fairbairn H. W. , Faure G. , Pinson Jr. W. H. , Hurley P. M.
Published: April 2011

The concordant norite, granophyre ("micro-pegmatite"), rhyodacite tuff, slate, and graywacke ("sandstone") that form the rimmed elliptical basin at Sudbury, Ontario, are unique in the Canadian Shield and exhibit several features characteristic of lopoliths. A previous Rb–Sr whole-rock isochron for the norite-granophyre intrusive pair gave 1704 ± 19 m.y., with initial 87Sr/86Sr of 0.7052 ± 0.0003. New work presented here concerns the sediments and tuff. An isochron for the slate–graywacke sedimentary sequence in the center of the basin gives 1720 ± 30 m.y., with initial 87Sr/86Sr of 0.7062 ± 0.0018. A definitive age for the underlying tuff has not been obtained owing to scatter and small Rb/Sr range; however, its concordance and chemical relationships with both sediments and norite–granophyre point to an equivalent age. The combined isotopic data for tuff and sediments give 1684 ± 43 m.y., with initial 87Sr/86Sr of 0.7092 ± 0.0015, in reasonable agreement with the norite–granophyre age. The decay constant λRb = 1.39 × 10−11 yr−1 has been used throughout.The investigation thus far supports consanguinity of the entire complex, with geologically rapid development about 1700 m.y. ago. It imposes no barrier due to age differences on either conventional models of lopolith generation or on generation initiated by meteoritic impact. It raises a problem concerning initial 87Sr/86Sr if impact is assumed. It rules out proposals to correlate the tuff–sediment sequence either with Keweenawan rocks (about 1000 m.y.) or with older volcanic sequences (2000 ± m.y.) outside the loplith.
Geochronology of the Yavapai Series of central Arizona
Authors: Lanphere Marvin A.
Published: April 2011

K–Ar mineral ages from a post-tectonic pluton give a minimum age of 1690 m.y. for deformation and metamorphism of the Precambrian Yavapai Series near Jerome, Arizona. Rb–Sr measurements of whole-rock samples of silicic metavolcanic rocks indicate an age of 1610 ± 85 m.y. for one locality of the Deception Rhyolite and an 'age' of 1640 ± 38 m.y. for a suite of samples from the Ash Creek Group. Samples of the Alder Group give ages of less than 1600 m.y., but since the data and field relations suggest that these samples have lost radiogenic strontium, this age is probably a minimum.
Sedimentary and paleontological features of the Tertiary–Cretaceous rocks of Somerset Island, Arctic Canada
Authors: Dineley D. L. , Rust B. R.
Published: April 2011

A 300 m succession of non-marine clastic rocks, herein termed the Idlorak Formation, lies in a graben on the Precambrian basement of Somerset Island, Arctic Canada. The indigenous microflora is probably late Cretaceous or Tertiary in age. Abraded fish remains, reaching 65 cm in length, include arthrodires, other placoderms, and crossopterygians, which were probably derived locally from former outcrops of Upper Devonian rocks.Eighty percent of the Idlorak Formation is well-sorted quartz sandstone; the remainder is shale, siltstone, and minor conglomerate. Abundant large-scale cross-stratification indicates fluvial transport from the north, and the presence of Lingula suggests a marginal coastal environment such as a delta. The largely arenaceous Griper Bay Formation and equivalent formations, now nearly 400 km to the north, may have formerly extended southward to provide the bulk of the source material.
Junction of deep structures of the Carpatho-Balkan region with those of the Black and Adriatic Seas
Authors: Subbotin S. I. , Sollogub V. B. , Prosen D. , Dragasevic T. , Mituch E. , Posgay K.
Published: April 2011

Deep crustal structures have been studied on the territory of southeastern Europe by means of deep seismic soundings (DSS), and a topographic scheme of the Mohorovičić (Moho) discontinuity has been compiled.Crustal thickness varies from 20–25 km in the Black Sea Depression and the Pannonian Middle Massif to 50–55 km in the Crimea, Carpathians, and Dinarides. Mountain 'roots' have been revealed along the Moho discontinuity and 'antiroots' along the 'basaltic' layer surface in the highland areas. Different relationships between the Moho discontinuity and the Conrad and basement surfaces are established, from the conformable to the inverse. Different types of crust are distinguished, characterized by different thicknesses of the individual layers as well as by deep fractures causing a block structure.The depressions of the Black and Adriatic Seas are characterized by the presence of intensive positive gravity anomalies, which are due to zones of subcrustal substance of higher density and thinning of the crust owing to a smaller thickness of the 'basaltic' or 'granitic' layers. The smaller thickness of the crust or its individual layers is associated with vertical and horizontal movements of the crust, which had resulted in over-thrusts, overthrust sheets, etc.The earth's crust of a continental type is contiguous with a sub-oceanic crust of the Black and Adriatic Seas along the deep fractures. The main fracture in the Black Sea is found near the south coast of the Crimean Peninsula, and the second one in the zone of a wedging out of the 'granitic' layer. The crustal region between these fractures should be related to an intermediate type.
Ribbed moraine: Till-fabric analysis and origin
Authors: Cowan W. R.
Published: April 2011

The origin of a glacier-molded drift landform known as ribbed moraine and its relationship to fluted ground moraine and eskers are examined. The principal method of study is that of till-fabric analysis.Proximal fabrics indicate some up-glacier imbrication into the slopes, while distal fabrics are slope conformable. Fabrics from curved ridges as well as from the ribbed moraine–fluted ground moraine junctures appear to have directional components additional to that of regional glaciation.The recurrent ridges of ribbed moraine transverse to the direction of regional glaciation are deduced as having resulted from a reactivation of a retreating ice front leading to the bulldozing and piling up of proglacial debris which was finally overridden. The adjacent and sometimes superposed flutings are attributed to changes in flow patterns within the ice during and after overriding. Eskers examined appear to be post-ribbed moraine in age and therefore exerted no influence on the formation of ribbed moraine. The periodicity of the ribbed moraine is not time significant and is believed to be related to the thickness of ice and the quantity of proglacial debris available.
Magnetization of the Perry Formation of New Brunswick, and the rotation of Newfoundland
Authors: Robertson W. A. , Roy J. L. , Park J. K.
Published: April 2011

The remanent magnetization of the Upper Devonian Perry Formation of New Brunswick consists of two components B and A acquired before and after folding (pre-Westphalian D) respectively. The stability spectra of these components overlap and it is therefore difficult to define them accurately and calculate their errors. The best estimate of the older (B) component (with respect to bedding) is 175,+23 (pole 32° N, 118° E), but this may be in error by 15° or more: its age is considered to be Late Devonian or Mississippian. The best estimate of the younger (A) component (with respect to present horizontal) is also 175, +23 and its age is considered to be early Pennsylvanian or older. The uncertainty in estimating these directions, however, means that the paleomagnetic observations, although they do not preclude the possibility that Newfoundland has rotated, also do not provide independent evidence that this has occurred, as has been suggested.
The chemical evolution of the Canadian Shield
Authors: Fahrig W. F. , Eade K. E.
Published: April 2011

Archean surface crystalline rocks of the Canadian Shield differ chemically from those of Proterozoic age. The younger rocks are higher in K2O, TiO2, U, and Th and lower in Na2O, Cr, Ni, and possibly MgO and CaO. This may be a secondary result of vertical chemical zoning of the crust as a result of metamorphism accompanied by anatectic melting. The erosion of a zoned crust would result in the enrichment of elements such as K, Na, Si, U, and Th in younger sedimentary basins. The crystalline crust subsequently evolved from the sediments of these basins would be enriched in these elements relative to older rocks exposed as a result of erosion. The secular chemical evolution of the shield may also reflect a progressive, though irregular, shift in the composition of new sial being added to the crust. Evidence for this progressive change is found in the increase in the abundance of potassium of successive dike swarms that were feeders of new sial to the upper part of the crust.
Patterned ground in Southeastern Newfoundland
Authors: Henderson E. P.
Published: April 2011

Patterned ground is present and active on the Avalon Peninsula of Newfoundland, though in the main it is restricted to higher exposed areas of the southern half of that peninsula. The patterned ground forms resemble types previously considered confined, if at low elevations, to more northerly latitudes. Also, a permafrost base had been assumed necessary for construction of certain of the structures, but there presently is no permafrost anywhere on the Avalon Peninsula. Formation of the patterned ground was caused largely by low summer temperatures, general thinness or absence of snow cover in winter, and a strongly maritime climate. Those factors, where combined with sparse vegetation and a hard till underlying the frost-churned soils, can produce most typical patterned ground forms.Presence of such well-developed features on the Avalon Peninsula indicates that fossil frost structures elsewhere should not everywhere be assumed to indicate much more severe climate, perhaps with permafrost, in the past. They may merely indicate an earlier, intensely maritime-type climate with a moderate winter, but a low mean, annual temperature.
Pleistocene ungulates from the Bow River gravels at Cochrane, Alberta
Authors: Churcher C. S.
Published: April 2011

Five ungulates are reported from gravels comprising the second major terrace above the Bow River's north bank at Cochrane, Alberta. These ungulates are Cervus canadensis (wapiti), Rangifer tarandus (caribou), Ovis canadensis (mountain sheep), Bison occidentalis (extinct western bison), and Equus conversidens (extinct Mexican ass). E. conversidens was previously known from middle and late Pleistocene beds of the southern United States and Mexico and is here reported from the post-Wisconsin Pleistocene of Alberta and possibly Saskatchewan. Radiocarbon analysis of Bison bones from the gravels yielded two dates that averaged 11 065 B.P.
GOWN—A computer storage system for groundwater data
Authors: Gilliland J. A. , Treichel A.
Published: April 2011

GOWN is intended to be a tool to assist the scientist and manager. Design of the system emphasizes flexibility, utility, and compatibility. GOWN is a computer-operated data-processing system using magnetic tape as the basic storage medium.The programs to create well-log, well-data, and catalog files have been developed and other files can be added as needed. Extensive use of parameter codes and mnemonic codes is made, enabling data from a variety of sources to be handled. A library of retrieval routines will be developed so that data can be presented as graphs, maps, or sections.It is anticipated that GOWN will substantially increase the efficiency of the scientist by relieving him of the load of routine data manipulation.
A probable meteorite origin for Mistastin Lake, Labrador
Authors: Taylor F. C. , Dence M. R.
Published: April 2011

Mistastin Lake, Labrador, latitude 55°53′ N, longitude 63°18′ W, is a roughly circular lake with a large central island lying in a marked depression. A meteorite impact origin is indicated by shock metamorphism features and fracturing of anorthosite and adamellite on the central island and of inclusions in flat-lying igneous rocks on the western shore. The crater had an original diameter of about 20 km and an age, by whole-rock K–Ar determination, of 202 ± 25 m.y.
New spinulose Aquilapollenites spp. from the Edmonton Formation (Maestrichtian), Alberta, Canada
Authors: Srivastava Satish K.
Published: April 2011

Eighteen new species belonging to the genus Aquilapollenites are formally described from the Edmonton Formation (Maestrichtian), Alberta, Canada. All these species have reticulate sexine with spinules.