bluuebunny/crossref_metadata_2025 huggingface dataset:
Postglacial crustal movements in southwestern British Columbia and adjacent Washington state
Authors: Mathews W. H. , Fyles J. G. , Nasmith H. W.
Published: October 2008

Records of former land–sea relationships in southwestern British Columbia and adjacent Washington State have been established in considerable detail by terrestrial and marine stratigraphy, by terrestrial and littoral landforms, and by archeological remains, aided by radiocarbon dating of shells, wood, peat, and charcoal from critical sites. These records indicate submergent conditions at the time of retreat of the Vashon ice sheet, 13 000 y ago, followed by an unusually quick emergence of several hundred feet by about 12 000 y ago. In the north-east and north of the area studied, this emergence was followed by a submergence of some hundreds of feet during the next half millennium preceding the Sumas ice advance. During and following this ice advance, land again became emergent, and during the period 9 000 to 6 000 y ago sea level stood approximately 35 ft (10 m) below the present shore in some parts of the area. The shore has stood close to its present level for the last 5 500 y in all parts of the area.Early movements were dominantly isostatic. The pre-Sumas submergence is of problematical origin. Sea level shifts since 8 000 y ago appear to be dominantly eustatic; isostatic movements were evidently essentially complete by this time. In historic time very small changes shown by tide gauges and precise levelling may be tectonic.
Present and postglacial rates of uplift for glaciated northern and eastern North America derived from postglacial uplift curves
Authors: Andrews J. T.
Published: October 2008

Average rates of postglacial uplift reach a maximum value of nearly 4 m 100 y−1 over southeastern Hudson Bay, and another high cell, with rates of about 2.5 m 100 y−1, lies between Bathurst Inlet and Southampton Island. Current rates of uplift are underestimated if exponential curves are fitted solely to dated raised marine deposits without considering the amount of future recovery. Rates of rebound are, instead, derived from A/t where A is uplift in the first 1000 y since deglaciation, and t is time since deglaciation. For the northwest margin of the former ice sheet coefficients of determination for rate of uplift, at specific times, as a function of distance are [Formula: see text]. Maps of rates of uplift for northern and eastern North America are presented for 8000 y B.P., 6000 y B.P. and the present day. They reveal the existence of three uplift centers and show that rates of uplift declined from a maximum of 10 to 12 m 100 y−1, immediately following deglaciation, to a current maximum of about 1.3 m 100 y−1. Agreement is satisfactory when calculated rates of uplift are compared with those derived from geological observations, radiocarbon dates, and from water-level records. A final map shows isochrones on the uplift rate of ~1 m 100 y−1. The rate dropped to this value about 10 000 y ago on the outer northwest and southeast coasts, whereas the value might not be reached for another 2000 y in southeastern Hudson Bay.
Structural analysis of shatter cones from the Slate Islands, northern Lake Superior
Authors: Stesky R. M. , Halls H. C.
Published: October 2008

Shatter cones, an unusual type of fracturing produced by intense shock, are found widespread on the Slate Islands in northern Lake Superior. The islands have been interpreted as the central uplift of an eroded meteorite impact crater about 30 km in diameter. The cones are best developed in certain rock types: Keweenawan basalt flows and chilled margins of associated feeder dikes, and Archean diorite and foliated feldspar porphyry. At certain sites cones show an elongate cross section and anomalous orientation caused by foliation-induced elastic anisotropy in the host rock.In general the cones point upward and inward toward the centre of the Slate Islands group. After structural correction of some sites according to paleomagnetic data, there is increased convergence of cone axes to a central focus (the inferred impact point) that occurs at a height of about 1 km above the present land surface.
Properties and genesis of a soil and the underlying gibbsite-bearing saprolite, Cape Breton Island, Canada
Authors: McKeague J. A. , Grant D. R. , Kodama H. , Beke G. J. , Wang C.
Published: October 2008

Brownish yellow saprolite derived from granite gneiss is exposed beneath 1–2 m of reddish brown till along a roadcut in the Cape Breton Highlands. The strongly acid soil is similar to other Podzolic soils of the region except for the presence of gibbsite in the silt and clay fractions. In the saprolite, feldspar and biotite have weathered to poorly crystalline kaolinite, gibbsite, and a minor component of iron oxide. The poorly crystalline kaolinite does not occur in the overlying till.The evidence presented is consistent with the view that the area was covered either by "cold-based" or by stagnant "warm-based" glaciers that eroded the pre-Quaternary surface only slightly and deposited a thin, discontinuous veneer of till derived mainly from local bedrock and saprolite. Weathering products from the saprolite are probably incorporated commonly in tills of the area. During the formation of soils in these tills the poorly crystalline kaolinite and most of the gibbsite are either transformed to other minerals or dissolved and removed in solution.
Subsidence and thermal history of Queen Charlotte Basin
Authors: Yorath C. J. , Hyndman R. D.
Published: October 2008

A tectonic model for the formation, subsidence, and thermal history of Queen Charlotte Basin is developed. Based upon regional geological and geophysical data, subsidence data from offshore wells in Hecate Strait and Queen Charlotte Sound, and thermal criteria derived from present heat flow and vitrinite reflectance information, Queen Charlotte Basin is seen to have resulted from two distinct mechanisms. (1) During a period of broad regional uplift, rifting and crustal extension occurred in Queen Charlotte Sound up to about 17 Ma ago and the Queen Charlotte Islands were displaced northwards toward their present position by transcurrent motion along the Louscoone Inlet – Sandspit fault system. The rifting generated a significant thermal anomaly and a restricted deep basin as a consequence of crustal thinning and subsequent thermal cooling. (2) Beginning about 6 Ma ago, oblique underthrusting commenced along the margin, resulting in flexural uplift of the western part of the Queen Charlotte Islands and companion subsidence in Hecate Strait and Queen Charlotte Sound. The underthrusting caused rapid cooling of the old rift basins. This phase of subsidence has continued at a decreasing rate until the present.The tectonically generated subsidence in the basin has been estimated by correcting the well data for sediment compaction, paleo water depth, and sediment loading effects. At the site of the Harlequin well in the Queen Charlotte Sound rift, with the termination of extension and associated volcanism, the basin was 1500–2000 m deep and contained little sediment. Model calculations show that this depth is consistent with the estimated extension of about 70 km and a resulting crustal thinning to 8–10 km.Models for the lithosphere flexure generated by underthrusting are constrained by the geological evidence for uplift and erosion of over 5 km of material from the western portion of the Queen Charlotte Islands and the exponentially slowing subsidence to a present regional basement depth of 2 km in Hecate Strait. An excellent fit to the pre-erosion surface profile onshore and pre-Skonun basement surface offshore is obtained with a model having underthrusting on a 30° thrust at a 10 mm year−1 orthogonal component of convergence. The flexure generated by underthrusting, which is particularly well documented in the Queen Charlotte region, appears to be a feature of most subduction zones.Vitrinite reflectance data, present heat flow estimates from the wells, and thermal modelling indicate that the heat flux in Queen Charlotte Basin was much higher in the past than at present, particularly in Queen Charlotte Sound. A model is proposed with high heat flow generated by rifting prior to 17 Ma ago, followed by cooling from the underthrust oceanic lithosphere.
Interpretation of the aeromagnetic anomalies of southern Vancouver Island
Authors: Arkani-Hamed J. , Strangway D. W.
Published: October 2008

A low-pass filtered aeromagnetic map of southern Vancouver Island is inverted into a magnetization-contrast map that illustrates the lateral variations in the magnetization of the crust. The Island Intrusions and the West Coast Crystalline Complex are characterized by high magnetization relative to the other lithologic groups. The Island Intrusions form an almost continuous pluton in the deeper part of the crust. The low-magnetic Leech River Formation thickens northward. The almost uniform magnetic signature of the Leech River Formation in the east–west direction indicates that the crustal structure revealed from the Lithoprobe seismic results is typical throughout the formation west of the Survey Mountain fault. A low-magnetic zone, elongated in the northwest–southeast direction, cuts through the high-magnetic Metchosin basalts from the southern tip of the island to the Leech River fault. It coincides with the Sooke gabbros exposed in the southern tip of the island, implying that the gabbros probably cut the entire Metchosin basalts at depth.
High-resolution palaeomagnetic study of Late Pleistocene sediments from Baffin Bay:first results
Authors: Thouveny N.
Published: October 2008

The detailed palaeomagnetic study of core 85027016, collected in central Baffin Bay, confirms the occurrence of anomalous directions in the depositional remanent magnetization, previously observed in the upper part of the Pleistocene sequence. Chronology and sedimentation rates are discussed on the basis of new 14C ages, 18O isotopic stratigraphy, and palaeoclimatic arguments provided by other works. Two successions of anomalous inclinations are recorded between 15 000 and 30 000 years BP, preceded by long-period secular variations. The possible occurrence of geomagnetic excursions in this region is discussed in considering contemporaneous high-resolution palaeomagnetic records of the Northern Hemisphere.
An assessment of the megathrust earthquake potential of the Cascadia subduction zone
Authors: Rogers Garry C.
Published: October 2008

The active tectonic setting of the southwest coast of Canada and the Pacific northwest coast of the United states is dominated by the Cascadia subduction zone. The zone can be divided into four segments where oceanic lithosphere is converging independently with the North American plate: the Winona and the Explorer segments in the north, the larger Juan de Fuca segment that extends into both Canada and the United States, and the Gorda segment in the south. The oceanic lithosphere entering the Cascadia subduction zone in all segments is extremely young, less than 10 Ma. Of the other six zones around the Pacific where young (< 20 Ma) lithosphere is being subducted, five have had major thrust earthquakes (megathrust events) on the subduction interface in historic time. An estimation based on potential area of rupture gives maximum possible earthquake magnitudes along the Cascadia subducting margin of 8.2 for the Winona segment, 8.5 for the Explorer segment, 9.1 for the Juan de Fuca segment, and 8.3 for the South Gorda segment. Repeat times for maximum earthquakes, based on the ratios of seismic slip to total slip observed in other subduction zones, are predicted to be up to several hundred years for each segment, well beyond recorded history of the west coast, which began about 1800. Thus the lack of historical seismicity information provides a few constraints on the assessment of the seismic potential of the subduction zone.
Stratigraphy of the Aroostook–Percé Anticlinorium in the Gaspé Peninsula, Quebec
Authors: Malo Michel
Published: October 2008

In Quebec, the Aroostook–Percé Anticlinorium exposes two stratigraphic groups: the Honorat and the Matapédia. The terrigenous units of the Honorat Group form the core of the anticlinorium and are overlain by the carbonate sequence of the Matapédia Group. Each group comprises two formations. The Honorat is herein divided into two new formations, the Arsenault and the Garin, which are defined for the first time. The Matapédia Group includes the Pabos and White Head formations. The Pabos Formation, a transitional unit between the noncalcareous strata of the Honorat Group and the carbonate facies of the White Head Formation, is here redefined. The White Head Formation comprises four members. These two groups represent continuous sedimentation from the Late Ordovician (Caradocian) to the Early Silurian (Llandoverian).The lithostratigraphy of the type areas of the Honorat Group (Honorat Township region) and Pabos Formation (Chandler region) are fully described, whereas the lithostratigraphy of the type area of the White Head Formation (Percé area) is summarized only. The Arsenault, Garin, and Pabos formations and the Burmingham, Côte de la Surprise, L'Irlande, and Des Jean members of the White Head Formation constitute the stratigraphic sequence in the eastern part of the Aroostook–Percé Anticlinorium. These units are extended to the western part of the anticlinorium in Quebec and in New Brunswick, and also to other Late Ordovician – Early Silurian rocks in the Chaleur Bay and Gaspé – Connecticut Valley synclinoria.Rocks of the Aroostook–Percé Anticlinorium are interpreted as having been deposited by turbidity currents in a relatively deep water basin. Deposition evolved through time from terrigenous to limestone, reflecting a change in source areas.The Grand Pabos fault divides the Aroostook–Percé Anticlinorium between Percé and Carleton into two areas with stratigraphically different sequences. The northern area is dominated by carbonate rocks of the Matapédia Group, whereas the southern area is composed mainly of terrigenous facies of the Honorat Group. Carbonate sedimentation of the White Head Formation started during Late Ordovician time in the northern area but only during Early Silurian times in the southern area. The thickness of the carbonate strata, which reaches 2000 m in the northern area, diminishes to 150 m in the southern area.
The smallest ceratopsid skull–Judith River Formation of Alberta
Authors: Dodson Peter , Currie Philip J.
Published: October 2008

A partial skull found at Dinosaur Provincial Park, Alberta, in Upper Cretaceous (Campanian) sediments is the smallest specimen of a ceratopsid ever found, belonging to an animal about 1.1 m long. It represents an animal probably less than 2 years old, one fifth of its adult size. The shape of the squamosal and the thinness of the parietal suggest a tentative referral to Monoclonius. Strong positive allometric growth of the parietal fenestra is inferred.
Ice-free conditions in southwestern British Columbia at 16000 years BP
Authors: Clague John J. , Saunders Ian R. , Roberts Michael C.
Published: October 2008

New radiocarbon dates on wood from two exposures in Chilliwack valley, southwestern British Columbia, indicate that this area was ice free and locally forested 16 000 radiocarbon years ago. This suggests that the Late Wisconsinan Cordilleran Ice Sheet reached its maximum extent in this region after 16 000 years BP. The Chilliwack valley dates are the youngest in British Columbia that bear on the growth of the Cordilleran Ice Sheet.
Pétrographie et minéralogie des halos d'altération autour du gisement de Cigar Lake et leurs relations avec les minéralisations
Authors: Pacquet A. , Weber F.
Published: October 2008

Around the Cigar Lake orebody, the present zoneography of alteration halos reflects several alteration episodes, some of which are anterior to and others coeval with the mineralizing events and have a regional extension. The basement retromorphism is characterized by crystallization of muscovite with a low iron and magnesium content and of trioctahedral ferromagnesian chlorites. The later regolith alteration, more obvious at the top of the basement, is marked by iron-bearing 1T kaolinite, by hematite, and by local crandallite–florencite and diaspore. In the Athabasca sandstones far from any mineralization, the diagenetic quartzification was followed by crystallization of aluminous 2M hydromuscovite, dickite, and crandallite–goyazite.In the main pod, the uraninite mineralization was dated 1341 ± 12 Ma. In the sandstones, it is surrounded by ferromagnesian chlorites with a variable sudoitic character. This proximal alteration halo grades into a more distal envelope, visible in the sandstone and in the basement, that is composed of magnesian sudoite and 3T hydromuscovite. During this mineralizing event, dravite crystallized in the form of urchin-like clusters in the basement and xenotime overgrowths, around altered zircon, and apatite formed in the sandstones.Around the main pod and in some perched orebodies, an alteration zone of vanadium-bearing ferrikaolinite and iron-bearing 3T hydromuscovite, crosscut by a later siderite, surrounds the pitchblende dated 323 ± 4 Ma. Coffinite and an aluminous hydromuscovite crystallized during a later fracture event. The aluminous hydromuscovite also appears, with a silica–carbon–uranium complex, in perched mineralizations. Kaolinization and iron-sulfide oxidation into iron hydroxides occurred in perched orebodies that were more exposed to meteoric alteration.
Formation and evolution of the Cigar Lake uranium deposit based on U–Pb and K–Ar isotope systematics
Authors: Philippe S. , Lancelot J. R. , Clauer N. , Pacquet A.
Published: October 2008

A systematic geochronological study was conducted on the Cigar Lake uranium deposit. U–Pb and Pb–Pb systematics were applied to different types of uranium ore, and various associated sheet silicates were dated by the K–Ar method. These two approaches define a widespread retrograde metamorphic event in the basement, which occurred at about 1780 Ma during the Hudsonian orogeny, and a four-stage evolutionary model for the ore deposit. This model is compatible with the history of other unconformity-type, uranium deposits in the Athabasca Basin.The first stage in the evolution of the Cigar Lake uranium deposit is marked by uraninite crystallization at 1341 ± 17 Ma, which, in association with arsenides and sulpharsenides, constitutes the mineralization of economic interest (main orebody). The second stage, characterized by a Fe-kaolinite and Fe-illite paragenesis, occurred locally at about 900 Ma. The third stage involved uranium mobilization at about 325 Ma and is characterized by (i) preferential loss of radiogenic lead from primary uraninite and crystallization of pitchblende at the rims of uraninite grains and (ii) formation of pitchblende associated with Fe-sulphides or hematite in the main and perched orebodies. The last stage is characterized by recent alteration and coffinitization which have affected all ore types.
Sm–Nd, Pb–Pb, and Rb–Sr systematics of the basement in the Cigar Lake area, Saskatchewan, Canada
Authors: Pagel Maurice , Michard Annie , Juteau Martine , Turpin Laurent
Published: October 2008

The Sm–Nd, Pb–Pb, and Rb–Sr isotope geochemistry of graphitic metapelitic gneisses and their altered equivalents from the Cigar Lake area (Saskatchewan, Canada) has been investigated. Some granitic gneisses were also analyzed for Pb–Pb and Rb–Sr. Sm–Nd data show that the metapelitic gneisses are composed of detritus from heterogeneous, mainly mantle-derived Archean rocks (2.5–2.6 Ga) and that the Sm–Nd system has not been significantly perturbed during subsequent alteration and metamorphic events. The Pb–Pb age for samples of the less altered graphitic metapelitic gneisses is 1.77 ± 0.03 Ga. The crustal common Pb is located on the Pb–Pb isochron, but there are different zones with high and variable U/Pb ratios (μ = 15–280). The Pb–Pb age for the granitic gneisses is 1.79 ± 0.11 Ma. The Pb isotope data show that there has been no major uranium redistribution in the basement after the Hudsonian orogeny. However, there has been a strong perturbation of the U–Pb system in the regolithic zone beneath the Athabasca cover. In some samples, uranium was added during the mineralizing event. The Rb–Sr system in the graphitic metapelitic gneisses was also affected.The 87Sr/86Sr ratio in pitchblende is 0.709. At 1.3 Ga, there is a strong contrast between the 87Sr/86Sr ratio in the Athabasca sandstones (0.706–0.710) and the 87Sr/86Sr ratio in the metapelitic gneisses from the basement (0.725–0.775). The upper zone of the regolith is characterized by a low 87Sr/86Sr ratio (0.705–0.707). The Pb–Pb and Rb–Sr data are consistent with the circulation of a fluid with a low 87Sr/86Sr ratio, derived from the sedimentary cover; this fluid passed through the most permeable zones of the basement rocks, especially the regolith. The mineralizing fluid had a 87Sr/86Sr value typical of a fluid in equilibrium with the Athabasca sandstones.
Characterization of graphite alteration and bitumen genesis in the Cigar Lake deposit (Saskatchewan, Canada)
Authors: Landais Patrick , Dubessy Jean , Dereppe Jean-Marie , Philp R. Paul
Published: October 2008

Bitumens collected in the east zone of the Cigar Lake deposit have been analyzed by 13C nuclear magnetic resonance, pyrolysis – gas chromatography, Rock-Eval, and C. H, and O methods. Carbon and hydrogen isotopic compositions and uranium contents have been determined. Results indicate that the bitumens consist mainly of aromatic structures (Fa ≈ 60%) and have undergone a late oxidation process. Similarities in carbon isotopic composition (−27.5‰ > δ13C > −28.2‰) between barren bitumens (U < 300 ppm) and graphite collected in the basement gneisses, as well as evidence for progressive disorganization of graphite along a basement profile, suggest a genetic relationship between graphite and bitumens from the mineralized areas. The presence of amorphous carbon in pit structures inside graphite flakes close to the unconformity supports this assessment.Significant differences in geochemical and isotopic characteristics of the Cigar Lake barren bitumens and the Cluff Lake mineralized bitumens suggest that there are two possible mechanisms for their formation. Barren 13C-enriched bitumens could have formed directly by hydrogenation of amorphous carbon, whereas mineralized, isotopically light bitumens from Cluff Lake (δ13C ≈ 48‰) may result from the polymerization of light hydrocarbons around uraninite grains.
Variations chimiques et isotopiques de l'eau du sol lors de la reprise en gel d'une couche active sur pergélisol continu (Presqu'île de Brögger, Svalbard)
Authors: Marlin Christelle , Dever Laurent , Vachier Pierre , Courty Marie-Agnès
Published: October 2008

The isotopic and chemical composition of soil waters in a periglacial environment was studied during a 2 month period (89-10-07 to 89-11-09). The experimental site chosen is located near Ny Ålesund, Svalbard (79°N, 12°E). The profile studied is situated on a fluvioglacial terrace made up essentially of silicate material, which, however, contains secondary calcite that is crystallized at the base of the coarse fraction. During the summer season, an active layer of about 1.5 m thick is developed over the continuous permafrost. During the refrosting stage, two freezing waves advance through the profile, one from the surface and one from the permafrost. At the system closure at depth 0.6–0.7 m, a residual solution is generated, which evolves toward selective solute enrichment and stable isotope (18O, 2H) depletion. The chemical and isotopic data coupled with physicochemical measurements taken in situ show that during refrosting this solution is oversaturated relative to calcite. The resulting crystallization of calcite takes place in a closed system in the presence of soil-derived CO2, but is not in isotopic equilibrium with the solution. [Journal Translation]
Paleozoic metamorphism across the boundary between the Clements Markham fold belt and the Pearya terrane in northern Ellesmere Island, Canadian Arctic Archipelago
Authors: Klaper Eva M. , Ohta Yoshihide
Published: October 2008

Microstructural and petrological data suggest that a single episode of syn- to post-tectonic metamorphism affected the boundary region between the Clements Markham fold belt and Pearya, a postulated Caledonian terrane, during a mid-Paleozoic orogenic event in northern Ellesmere Island. The sedimentary rocks of the Clements Markham fold belt pass from chlorite to biotite to garnet grade over a distance of about 10 km as the contact with the Mitchell Point belt gneisses of Pearya is approached from the south. Foliation development and chevron-style folding was followed by the growth of the index minerals chlorite, biotite, chloritoid, garnet, staurolite, and kyanite in semipelitic rocks in four metamorphic zones. Thermobarometry of garnet porphyroblasts indicates peak metamorphic conditions of about 600 °C and 600 MPa in the highest grade rocks. Chloritoid-involving phase relations define an invariant point at 540 °C and 500 MPa only 2 km away from the highest grade zone. It may be concluded from the calculated pressure and temperature differences over this short distance that the isogradic surfaces of the post-chevron-folding metamorphism are steeply oriented. Much of the observed metamorphic pattern can, therefore, be explained as the result of a significant post-chevron-folding differential uplift (overthrusting) of the hot Mitchell Point belt gneisses relative to the Clements Markham fold belt. This indicates that the Mitchell Point belt forms a thrust sheet which overlies the Clements Markham fold belt and that the accretion of Pearya predates the Late Silurian.
The Yielding Behavior of Particulate Media
Authors: Frydman S. , Zeitlen J. G. , Alpan I.
Published: October 2008

This paper presents a discussion of the yielding behavior of particulate media during shearing, based on the results of a laboratory investigation of the stress–strain properties of samples of glass microspheres. The test program, carried out on hollow cylinder specimens, studied the effect of functions of the three stress invariants on the stress–strain behavior.It is suggested that a 'yield' point may be defined, below which relatively little interparticle slippage occurs. Below this yield point, stress–strain relations under any particular stress-path may be predicted from superposition of isotropic and deviatoric components. An initial yield point is defined which is shown to occur at a constant ratio of octahedral shear to normal stresses, so obeying an extended Von Mises type criterion.With regards to the post-yield-point behavior, an expression is developed for the yielding behavior, based on an assumed mechanism of energy dissipation within the mass. This yield relation expresses the lack of normality between the strain increment vector and the yield function, known empirically to exist in granular materials, and shows that the deviation from normality is constant, and related to the true angle of interparticle friction, [Formula: see text].
Instrumentation for Dykes on Permafrost, Kettle Generating Station
Authors: Gupta R. C. , Marshall R. G. , Badke D.
Published: October 2008

Kettle Generating Station is the second hydro electric project built in northern Manitoba in the zone of discontinuous permafrost. Most of the dykes at the project are directly founded on permafrost affected materials. With the impounding of the reservoir the permafrost in foundations will eventually thaw resulting in settlement and possible slumping of dykes. Instruments were installed in all earthfill structures and foundations to monitor their short and long term behavior. In addition, intensive instrumentation was carried out in two selected areas to assist in defining the relationship between the rates of thawing of permafrost and drainage of free water. This paper describes the instrumentation program for dykes on permafrost, the selection of instruments and their installation, and gives the performance evaluation of some of the instruments.
A Study of Some Factors Affecting the Thawing of Frozen Soils
Authors: Nixon J. F. , McRoberts E. C.
Published: October 2008

An analysis of the engineering behavior of a thawing soil requires knowledge of the rate of melting. Some solutions for heat transfer in thawing soils are reviewed. The relative importance of the thermal properties necessary for solution is assessed and some properties of frozen soil are found to be of secondary importance in a thawing problem. Some practical simplifications of the Neumann problem are considered and sample solutions are presented.Research into the geotechnical characteristics of thawing soil is suggested to be more relevant than continuing research on thermal properties.
Laboratory Investigation of Permeability Ratio of New Liskeard Varved Soil
Authors: Chan H. T. , Kenney T. Cameron
Published: October 2008

The results are reported of a laboratory testing program to determine the permeability ratio, rK, (ratio of coefficients of permeability for flow parallel to and perpendicular to the soil layers) of samples of New Liskeard varved soil. The maximum value of rK is less than 5, which is perhaps significantly smaller than values usually assumed for varved soils. To explain these results, tests were conducted to determine the permeability characteristics of the constituent soils of the varves. Information is given concerning the test methods, the determination of the influence on permeability of soil disturbance at the cut surfaces, and the finding that this soil behaved according to Darcy's law at small values of hydraulic gradient.
Foundation Performance of a 100-year-old Bridge
Authors: Legget R. F. , Peckover F. L.
Published: October 2008

The Miramichi bridges in New Brunswick, each of six 200-ft (61-m) spans, were built as part of the Intercolonial Railway by Sir Sandford Fleming in 1871–75. When construction of the Northwest Bridge started, it was found that early borings were incorrect and the layer of gravel and sand on which the piers were to rest was underlain by deposits of silty sand and clay–silt. The caissons of the piers were therefore enlarged in order to spread the load better. On observing settlements during construction, Fleming stopped the work and preloaded each pier in excess of the design load. He resumed construction when he observed that settlements had stopped.The level of the bridge piers has been measured periodically since 1914. Recent borings have been made, giving a basis for analysis of the bridge performance. Calculated primary settlements are compared with those measured during construction. Surveyed pier movements are adjusted to reduce errors, and compared with calculated secondary settlements. It is deduced that the piers have settled at a rate equal to or less than that indicated by the theory of secondary compression.The bridge is continuing to perform in a predictable and safe manner, providing an outstanding example of early Canadian engineering.
A Comparison of the T.R.R.L. and C.R.R.E.L. Tests for the Frost Susceptibility of Soils
Authors: Sutherland H. B. , Gaskin P. N.
Published: October 2008

The frost susceptibility criteria and laboratory frost heave tests of tte United Kingdom Transport and Road Research Laboratory (T.R.R.L.) and the United States Army Cold Regions Research and Engineering Laboratory (C.R.R.E.L.) were compared by testing four stabilized pulverized fuel ashes. The two tests led to very similar frost susceptibility classifications. The T.R.R.L. frost heave test was considered to be the more suitable test since it uses a simpler test procedure that also allows all specimens in a batch to be subjected to the specified test conditions.
The Stability of Thawing Slopes
Authors: McRoberts E. C. , Morgenstern N. R.
Published: October 2008

As a result of recent field exploration and study in the Mackenzie River Valley between Fort Simpson and Fort Good Hope, N.W.T., coupled with a review of the periglacial literature it is evident that thaw plays an important role in a wide range of landslide types associated with permafrost.This study seeks first to present a description of the most common types of thaw-dominated landslide forms. Within this descriptive framework two important mass movement models, the thaw–consolidation model and the ablation model are considered. Available case records are reviewed in relation to the landslide types and other failure mechanisms are briefly considered.
Interaction of Superstructure–Soil under Restrained Settling
Authors: Komornik A. , Mazurik A.
Published: October 2008

A solution to the behavior of a statically indeterminate structure founded on discrete saturated clay supports undergoing one-dimensional consolidation settlements is presented.This behavior is analyzed by a step-by-step approach in short time intervals, with the stiffness matrix of the structure taken into consideration and its consolidation settlements corrected for the time changes of the support reactions. This correction is based on the superposition integral principle of viscoelastic bodies.The time variation of the settlements and reactions throughout the primary consolidation stage is obtained with the aid of a computer program, based on soil data and on the time curves of the clay under each footing.A model was built in the laboratory, and the theory was verified on a system of three consolidometers connected by steel beams for settlement restraint. The tests were in good agreement with the computer solution and revealed the extreme stress conditions acting on the structure and on the soil during the consolidation process.
Blackstrap Lake Ice Cover Parking Lot
Authors: Meneley W. A.
Published: October 2008

During the Canada Winter Games (1971) more than 4000 cars were parked on the ice cover of Blackstrap Lake during the skiing events on Mount Blackstrap. The rapid increase in winter recreation activities will result in increased use of ice covers for sporting events and parking. Ice thickness and buoyancy measurements were made at regular intervals over the lot during the 3 weeks immediately prior to the Winter Games. Continuous recordings of the ice surface deflection were obtained in the critical loading area. Systematic loading trials of increased magnitude were carried out to measure the static and dynamic performance of the ice cover. During the Winter Games the design load distribution was adjusted daily so that it was equal of less than the observed buoyancy of the ice cover in the parking area. This load distribution was achieved by controlling the parking density. This criterion provides a conservative estimate of the allowable distributed load for loading periods of several hours duration.The procedures developed provide a reasonable guideline for the safe use of freshwater covers for similar events.
The Performance of Foundations on Various Soils Stabilized by the Vibro-compaction Method
Authors: Baumann V. , Bauer G. E. A.
Published: October 2008

The improvement of weak or loose soil deposits by the vibrational technique has now become a well established method. Loose or medium dense sands can be compacted with slender, cylindrical vibrators (vibro-compaction method). Cohesive or organic soil can be improved by their partial displacement or replacement with selected granular material which is vibrated into the parent soil (vibro-replacement method). Compaction depth up to 30 m (100 ft) can be achieved.This paper describes the method of construction of compaction columns and stone columns. Method of estimating the settlement of the improved soil under given load conditions is presented. The applicability and limits of the process are outlined.Two case histories are discussed and they were chosen for their various degrees of difficulties encountered in the subsoil and because the settlement specifications placed very strict limits on the foundation performance.
Behavior of Circular Footings and Plate Anchors Embedded in Permafrost
Authors: Ladanyi B. , Johnston G. H.
Published: October 2008

The purpose of this paper is to develop a method for predicting the creep settlement and the bearing capacity of frozen soils under deep circular loads. The theory uses experimentally determined creep parameters of frozen soil and is intended to be applicable to the design of deep circular footings and screw anchors embedded in permafrost soils. On the basis of available experimental evidence, it was concluded that a mathematical model different from that usual in soil mechanics should be used in solving the time-dependent bearing capacity problem of such footings. The solution proposed in the paper was obtained by using the mathematical model of an expanding spherical cavity in a nonlinear viscoelastic-plastic medium with time, temperature, and normal pressure dependent strength properties. For a given footing or anchor, the theory furnishes either isochronous load-displacement curves, or load-creep rate curves, or a time-dependent bearing capacity for which formulas and graphs of nonlinear elastic-plastic bearing capacity factors are supplied.The theoretical predictability of creep rates and ultimate failure loads was checked against the results of screw anchor tests carried out by the Division of Building Research, N.R.C.C., at a permafrost site in Thompson, Manitoba. It was found that the use in the theory of the creep parameters determined by creep-pressuremeter tests performed at the site, resulted in a satisfactory agreement between the predicted and the observed behavior.
Dynamic Stiffness and Damping of Piles
Authors: Novak Milos
Published: October 2008

Dynamic response of footings and structures supported by piles can be predicted if dynamic stiffness and damping generated by soil–pile interaction can be defined. An approximate analytical approach based on linear elasticity is presented, which makes it possible to establish the dimensionless parameters of the problem and to obtain closed-form formulas for pile stiffness and damping. All components of the motion in a vertical plane are considered; that is, horizontal as well as vertical translations and rotation of the pile head. The stiffness and damping of piles are defined in such a way that the design analysis of footings and structures resting on piles can be conducted in the same way as is applied in the case of shallow foundations.
Ice Bridges of the James Bay Project
Authors: Michel B. , Drouin M. , Lefebvre L. M. , Rosenberg P. , Murray R.
Published: October 2008

In 1972 and 1973, a winter road crossing eight rivers was built in the James Bay territory to enable the installation of camps and the mobilization of all equipment, materials and fuel needed for the construction of a permanent road leading to the La Grande River. This paper reports on the bearing capacity theory, design, site selection, construction and testing of the ice bridges spanning the main rivers.
Le perméamètre autoforeur
Authors: Baguelin F. , Jezequel J. F. , Mehaute A. Le
Published: October 2008

A usual method for measuring the coefficients of permeability and consolidation of fine grained soils in situ is by means of permeameters installed by driving or pushing into the soil. The disadvantage of this method is that it produces a change in the properties to be measured.A new apparatus, called selfboring permeameter, is presented here, the particularity of which is that it can be installed without disturbing the soil. [Journal translation]
Brazilian Tensile Test for Soils
Authors: Krishnayya A. V. G. , Eisenstein Z.
Published: October 2008

Analysis and design of impermeable cores of earth dams against cracking require knowledge of the tensile strengths and tensile stress–strain relationships of the concerned soils. The same is needed for any stress and deformation analysis of an earth structure when a portion of it is expected to be in tension. In order to investigate behavior of soils in tension the Brazilian tensile test has been employed and found advantageous over other methods. However the interpretation of results of this test is involved because of the biaxial stress conditions existing at the center of the test specimen. Neglecting this fact leads to erroneous evaluation of the test results, particularly if the moduli in tension and compression differ. A numerical stress solution which considers the difference between compressive and tensile moduli with respect to tensile strength and tensile stress–strain relationship is developed. The magnitude of errors associated with the incorrect assumption of equal modulus in tension and compression is also investigated. The developed procedures of analytical evaluation of a Brazilian test are illustrated in the case of Mica Till, which is considered to be a typical example of a low plastic soil used in cores of earth dams. The results indicate that the Brazilian tensile test is a simple and accurate testing method, requiring however a proper consideration of the difference between a modulus in tension and compression.
Sample Disturbance in Soft Alluvial Clyde Estuary Clay
Authors: McGown A , Barden L. , Lee S. H. , Wilby P.
Published: October 2008

The alluvium of the Clyde Estuary provides the foundation material for a number of medium rise developments in the Glasgow area. Standard site investigation and testing techniques often result in an expensive foundation design involving piling. A more sophisticated investigation conducted at Laurieston, has afforded a chance to compare the disturbance due to different qualities of sampling. The degree of disturbance to macro- and microstructure has been assessed using standard photographic techniques and a scanning electron microscope. The effect of disturbance on shear strength has been measured using hand vane and triaxial tests; and on consolidation and compression parameters using Rowe cells of different sizes. On the basis of the standard and the improved site investigations two foundation designs have been prepared and their cost compared.
Settlement analysis of the Gloucester test fill
Authors: Lo K. Y. , Bozozuk M. , Law K. T.
Published: October 2008

This paper reports the observation and analysis of the rate and magnitude of settlement under the test embankment at Canadian Forces Station Gloucester. The embankment has been in existence for 7 years and, because of extensive instrumentation, a sufficiently complete record has emerged. An advanced finite element method has been used for the computation of the induced stresses in the foundation soil.Both block samples and 5 in. (12.7 cm) diameter Osterberg samples were recovered at various depths from the site. An experimental program, including the use of the 6 in. (15.2 cm) Rowe cell, has been carried out and an analysis of the test results based on the Gibson and Lo theory. The test results have also been used in the estimation of the field performance.From the present study it is found that: the coefficient of consolidation and the primary and secondary compressibility can be adequately determined from samples of size 4.5 in. (11.3 cm) diameter by 2 in. (5.1 cm) high or larger; the secondary compression contributes significantly to the total settlement for the soil considered; and the Gibson and Lo theory predicts fairly accurately both the time rate and magnitude of settlement in the field.
Winter earthwork: embankment construction using frozen soil
Authors: Alkire Bernard D. , Haas Wilbur M. , Botz James J.
Published: October 2008

Construction of embankments using frozen soils can cause excessive settlement and loss of stability after the soil thaws. This paper contains observations and test results obtained during cold weather construction of a small embankment. Included in the construction phase was ripping of a frozen granular soil, placing and compacting frozen embankment material, and installation of settlement plates and thermistors. Field tests were conducted to determine the size and gradation of the frozen chunks used in the embankment, monitor dry density and moisture content during compaction of the fill, and measure settlement and soil temperatures within the embankment. Results from the field tests were analyzed to assess the effectiveness of field compaction of frozen soil and to quantify settlements that occur as the soil thaws. The results provide the basis for recommendations concerning winter earthwork.
Density and compressibility characteristics of air–water mixtures
Authors: Fredlund D. G.
Published: October 2008

The density and compressibility of miscible and immiscible air–water mixtures are formulated on the basis of the conservation of mass. Boyle's Law accounts for the compressibility of free air and Henry's Law accounts for the amount of air that goes into solution. The rate of air diffusion into water in the soil is used to choose either the case of complete solution or no solution of air. Formulas are given by which it is possible to predict the density and compressibility of the fluid phase of unsaturated soils.The difference between the air and water pressures in a soil is of interest only in the compressibility formulation. It is not necessary nor advisable to use Kelvin's capillary model equation to account for the difference in air and water pressure since it incorporates an unmeasurable variable, and gives rise to an anomaly. It is recommended that a measurable pore pressure parameter, Baw or Bwa be used in the solution of engineering problems.
Correlations between cone resistance and vane shear strength in some Scandinavian soft to medium stiff clays
Authors: Lunne T. , Eide O. , Ruiter J. de
Published: October 2008

Vane shear strength and cone resistance for Scandinavian soft to medium stiff clay has been compared for six different sites in Norway and Sweden.At five of the sites, three in Drammen, one in Onsøy, and one in Gøteborg, the clays have been sedimented in an entirely marin environment. At the Skå-Edeby site the conditions have been marine-brackish or brackish-marine.When compared with the standard field vane shear strength, the cone factor, Nk (in the formula: qc = Nk∙[Formula: see text]f + γ∙z), varies between 13 and 24 for the five marine clays. For the Skå-Edeby clay the Nk values lie in the range 8 to 12.Corrections of field vane shear strength result, for the five marine clays, in Nk values between 15 and 19 with an average of 17. This Nk value can be used for Scandinavian marine normally consolidated clays, but may not be valid in other types of clays. An example of this is the Skå-Edeby brackish-marine clay where the corrected Nk values fall between 11 and 13.
Predictions and observations on the behaviour of a warm gas pipeline on permafrost
Authors: Hwang C. T.
Published: October 2008

This paper deals with predictions and measured observations of the behaviour of a warm gas pipeline on permafrost. In the paper, descriptions of the theoretical background for a mathematical model developed by the Canadian Arctic Gas Study Limited will be made. The model incorporates the following aspects: (a) transient heat conduction mechanism during freezing and thawing in the ground, in which the latent heat is considered as a heat source in the energy balance equation; (b) heat exchange mechanism at the ground surface with respect to meteorological data such as ambient air temperature, solar radiation, greenhouse factor, wind velocity, snow depth, and evapotranspiration; and (c) changes in geometry of the thermal domain due to thaw subsidence.Verification of the model was made using field data obtained from a hot-berm module with a gas temperature of 65 °F (18.3 °C), at the Norman Wells Test Facility of Canadian Arctic Gas Study Limited. Good correlation was found for predicted and measured values of: (a) ground temperature profiles in instrumented locations, (b) ground surface settlement, (c) pipe settlement, and (d) heat flux around the pipe.